BFQ patches for 4.7. See http://algogroup.unimore.it/people/paolo/disk_sched/patches/4.7.0-v8/

5 files changed, 14678 insertions, 0 deletions

diff --git a/0000_README b/0000_README
index 05302096..1b5179e9 100644
--- a/0000_README
+++ b/0000_README
@@ -67,6 +67,22 @@ Patch:  5000_enable-additional-cpu-optimizations-for-gcc.patch
 From:   https://github.com/graysky2/kernel_gcc_patch/
 Desc:   Kernel patch enables gcc < v4.9 optimizations for additional CPUs.
 
+Patch:  5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.7.patch
+From:   http://algo.ing.unimo.it/people/paolo/disk_sched/
+Desc:   BFQ v7r11 patch 1 for 4.7: Build, cgroups and kconfig bits
+
+Patch:  5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.7.patch1
+From:   http://algo.ing.unimo.it/people/paolo/disk_sched/
+Desc:   BFQ v7r11 patch 2 for 4.7: BFQ Scheduler
+
+Patch:  5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.7.patch
+From:   http://algo.ing.unimo.it/people/paolo/disk_sched/
+Desc:   BFQ v7r11 patch 3 for 4.7: Early Queue Merge (EQM)
+
+Patch:  5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch2
+From:   http://algo.ing.unimo.it/people/paolo/disk_sched/
+Desc:   BFQ v7r11 patch 4 for 4.7: Early Queue Merge (EQM)
+
 Patch:  5010_enable-additional-cpu-optimizations-for-gcc-4.9.patch
 From:   https://github.com/graysky2/kernel_gcc_patch/
 Desc:   Kernel patch enables gcc >= v4.9 optimizations for additional CPUs.
diff --git a/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.7.patch b/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.7.patch
new file mode 100644
index 00000000..45d0b07d
--- /dev/null
+++ b/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r11-4.7.patch
@@ -0,0 +1,103 @@
+From feb58b4dd1e8fd895f28ba4c759e92febe316cb2 Mon Sep 17 00:00:00 2001
+From: Paolo Valente <paolo.valente@unimore.it>
+Date: Tue, 7 Apr 2015 13:39:12 +0200
+Subject: [PATCH 1/4] block: cgroups, kconfig, build bits for BFQ-v7r11-4.7.0
+
+Update Kconfig.iosched and do the related Makefile changes to include
+kernel configuration options for BFQ. Also increase the number of
+policies supported by the blkio controller so that BFQ can add its
+own.
+
+Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
+Signed-off-by: Arianna Avanzini <avanzini@google.com>
+---
+ block/Kconfig.iosched  | 32 ++++++++++++++++++++++++++++++++
+ block/Makefile         |  1 +
+ include/linux/blkdev.h |  2 +-
+ 3 files changed, 34 insertions(+), 1 deletion(-)
+
+diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
+index 421bef9..0ee5f0f 100644
+--- a/block/Kconfig.iosched
++++ b/block/Kconfig.iosched
+@@ -39,6 +39,27 @@ config CFQ_GROUP_IOSCHED
+ 	---help---
+ 	  Enable group IO scheduling in CFQ.
+ 
++config IOSCHED_BFQ
++	tristate "BFQ I/O scheduler"
++	default n
++	---help---
++	  The BFQ I/O scheduler tries to distribute bandwidth among
++	  all processes according to their weights.
++	  It aims at distributing the bandwidth as desired, independently of
++	  the disk parameters and with any workload. It also tries to
++	  guarantee low latency to interactive and soft real-time
++	  applications. If compiled built-in (saying Y here), BFQ can
++	  be configured to support hierarchical scheduling.
++
++config CGROUP_BFQIO
++	bool "BFQ hierarchical scheduling support"
++	depends on CGROUPS && IOSCHED_BFQ=y
++	default n
++	---help---
++	  Enable hierarchical scheduling in BFQ, using the cgroups
++	  filesystem interface.  The name of the subsystem will be
++	  bfqio.
++
+ choice
+ 	prompt "Default I/O scheduler"
+ 	default DEFAULT_CFQ
+@@ -52,6 +73,16 @@ choice
+ 	config DEFAULT_CFQ
+ 		bool "CFQ" if IOSCHED_CFQ=y
+ 
++	config DEFAULT_BFQ
++		bool "BFQ" if IOSCHED_BFQ=y
++		help
++		  Selects BFQ as the default I/O scheduler which will be
++		  used by default for all block devices.
++		  The BFQ I/O scheduler aims at distributing the bandwidth
++		  as desired, independently of the disk parameters and with
++		  any workload. It also tries to guarantee low latency to
++		  interactive and soft real-time applications.
++
+ 	config DEFAULT_NOOP
+ 		bool "No-op"
+ 
+@@ -61,6 +92,7 @@ config DEFAULT_IOSCHED
+ 	string
+ 	default "deadline" if DEFAULT_DEADLINE
+ 	default "cfq" if DEFAULT_CFQ
++	default "bfq" if DEFAULT_BFQ
+ 	default "noop" if DEFAULT_NOOP
+ 
+ endmenu
+diff --git a/block/Makefile b/block/Makefile
+index 9eda232..4a36683 100644
+--- a/block/Makefile
++++ b/block/Makefile
+@@ -18,6 +18,7 @@ obj-$(CONFIG_BLK_DEV_THROTTLING)	+= blk-throttle.o
+ obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o
+ obj-$(CONFIG_IOSCHED_DEADLINE)	+= deadline-iosched.o
+ obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched.o
++obj-$(CONFIG_IOSCHED_BFQ)	+= bfq-iosched.o
+ 
+ obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
+ obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
+diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
+index 3d9cf32..8d862a0 100644
+--- a/include/linux/blkdev.h
++++ b/include/linux/blkdev.h
+@@ -45,7 +45,7 @@ struct pr_ops;
+  * Maximum number of blkcg policies allowed to be registered concurrently.
+  * Defined here to simplify include dependency.
+  */
+-#define BLKCG_MAX_POLS		2
++#define BLKCG_MAX_POLS		3
+ 
+ struct request;
+ typedef void (rq_end_io_fn)(struct request *, int);
+-- 
+1.9.1
+
diff --git a/5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.7.patch1 b/5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.7.patch1
new file mode 100644
index 00000000..8a67a4b3
--- /dev/null
+++ b/5002_block-introduce-the-BFQ-v7r11-I-O-sched-for-4.7.patch1
@@ -0,0 +1,7097 @@
+From 1f07b3f666e6da78d10e62cfb9696242e5b3005e Mon Sep 17 00:00:00 2001
+From: Paolo Valente <paolo.valente@unimore.it>
+Date: Thu, 9 May 2013 19:10:02 +0200
+Subject: [PATCH 2/4] block: introduce the BFQ-v7r11 I/O sched for 4.7.0
+
+The general structure is borrowed from CFQ, as much of the code for
+handling I/O contexts. Over time, several useful features have been
+ported from CFQ as well (details in the changelog in README.BFQ). A
+(bfq_)queue is associated to each task doing I/O on a device, and each
+time a scheduling decision has to be made a queue is selected and served
+until it expires.
+
+    - Slices are given in the service domain: tasks are assigned
+      budgets, measured in number of sectors. Once got the disk, a task
+      must however consume its assigned budget within a configurable
+      maximum time (by default, the maximum possible value of the
+      budgets is automatically computed to comply with this timeout).
+      This allows the desired latency vs "throughput boosting" tradeoff
+      to be set.
+
+    - Budgets are scheduled according to a variant of WF2Q+, implemented
+      using an augmented rb-tree to take eligibility into account while
+      preserving an O(log N) overall complexity.
+
+    - A low-latency tunable is provided; if enabled, both interactive
+      and soft real-time applications are guaranteed a very low latency.
+
+    - Latency guarantees are preserved also in the presence of NCQ.
+
+    - Also with flash-based devices, a high throughput is achieved
+      while still preserving latency guarantees.
+
+    - BFQ features Early Queue Merge (EQM), a sort of fusion of the
+      cooperating-queue-merging and the preemption mechanisms present
+      in CFQ. EQM is in fact a unified mechanism that tries to get a
+      sequential read pattern, and hence a high throughput, with any
+      set of processes performing interleaved I/O over a contiguous
+      sequence of sectors.
+
+    - BFQ supports full hierarchical scheduling, exporting a cgroups
+      interface.  Since each node has a full scheduler, each group can
+      be assigned its own weight.
+
+    - If the cgroups interface is not used, only I/O priorities can be
+      assigned to processes, with ioprio values mapped to weights
+      with the relation weight = IOPRIO_BE_NR - ioprio.
+
+    - ioprio classes are served in strict priority order, i.e., lower
+      priority queues are not served as long as there are higher
+      priority queues.  Among queues in the same class the bandwidth is
+      distributed in proportion to the weight of each queue. A very
+      thin extra bandwidth is however guaranteed to the Idle class, to
+      prevent it from starving.
+
+Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
+Signed-off-by: Arianna Avanzini <avanzini@google.com>
+---
+ block/Kconfig.iosched |    6 +-
+ block/bfq-cgroup.c    | 1182 ++++++++++++++++
+ block/bfq-ioc.c       |   36 +
+ block/bfq-iosched.c   | 3754 +++++++++++++++++++++++++++++++++++++++++++++++++
+ block/bfq-sched.c     | 1200 ++++++++++++++++
+ block/bfq.h           |  801 +++++++++++
+ 6 files changed, 6975 insertions(+), 4 deletions(-)
+ create mode 100644 block/bfq-cgroup.c
+ create mode 100644 block/bfq-ioc.c
+ create mode 100644 block/bfq-iosched.c
+ create mode 100644 block/bfq-sched.c
+ create mode 100644 block/bfq.h
+
+diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
+index 0ee5f0f..f78cd1a 100644
+--- a/block/Kconfig.iosched
++++ b/block/Kconfig.iosched
+@@ -51,14 +51,12 @@ config IOSCHED_BFQ
+ 	  applications. If compiled built-in (saying Y here), BFQ can
+ 	  be configured to support hierarchical scheduling.
+ 
+-config CGROUP_BFQIO
++config BFQ_GROUP_IOSCHED
+ 	bool "BFQ hierarchical scheduling support"
+ 	depends on CGROUPS && IOSCHED_BFQ=y
+ 	default n
+ 	---help---
+-	  Enable hierarchical scheduling in BFQ, using the cgroups
+-	  filesystem interface.  The name of the subsystem will be
+-	  bfqio.
++	  Enable hierarchical scheduling in BFQ, using the blkio controller.
+ 
+ choice
+ 	prompt "Default I/O scheduler"
+diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
+new file mode 100644
+index 0000000..8610cd6
+--- /dev/null
++++ b/block/bfq-cgroup.c
+@@ -0,0 +1,1182 @@
++/*
++ * BFQ: CGROUPS support.
++ *
++ * Based on ideas and code from CFQ:
++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
++ *
++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
++ *		      Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
++ * file.
++ */
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++
++/* bfqg stats flags */
++enum bfqg_stats_flags {
++	BFQG_stats_waiting = 0,
++	BFQG_stats_idling,
++	BFQG_stats_empty,
++};
++
++#define BFQG_FLAG_FNS(name)						\
++static void bfqg_stats_mark_##name(struct bfqg_stats *stats)	\
++{									\
++	stats->flags |= (1 << BFQG_stats_##name);			\
++}									\
++static void bfqg_stats_clear_##name(struct bfqg_stats *stats)	\
++{									\
++	stats->flags &= ~(1 << BFQG_stats_##name);			\
++}									\
++static int bfqg_stats_##name(struct bfqg_stats *stats)		\
++{									\
++	return (stats->flags & (1 << BFQG_stats_##name)) != 0;		\
++}									\
++
++BFQG_FLAG_FNS(waiting)
++BFQG_FLAG_FNS(idling)
++BFQG_FLAG_FNS(empty)
++#undef BFQG_FLAG_FNS
++
++/* This should be called with the queue_lock held. */
++static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
++{
++	unsigned long long now;
++
++	if (!bfqg_stats_waiting(stats))
++		return;
++
++	now = sched_clock();
++	if (time_after64(now, stats->start_group_wait_time))
++		blkg_stat_add(&stats->group_wait_time,
++			      now - stats->start_group_wait_time);
++	bfqg_stats_clear_waiting(stats);
++}
++
++/* This should be called with the queue_lock held. */
++static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
++						 struct bfq_group *curr_bfqg)
++{
++	struct bfqg_stats *stats = &bfqg->stats;
++
++	if (bfqg_stats_waiting(stats))
++		return;
++	if (bfqg == curr_bfqg)
++		return;
++	stats->start_group_wait_time = sched_clock();
++	bfqg_stats_mark_waiting(stats);
++}
++
++/* This should be called with the queue_lock held. */
++static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
++{
++	unsigned long long now;
++
++	if (!bfqg_stats_empty(stats))
++		return;
++
++	now = sched_clock();
++	if (time_after64(now, stats->start_empty_time))
++		blkg_stat_add(&stats->empty_time,
++			      now - stats->start_empty_time);
++	bfqg_stats_clear_empty(stats);
++}
++
++static void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
++{
++	blkg_stat_add(&bfqg->stats.dequeue, 1);
++}
++
++static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
++{
++	struct bfqg_stats *stats = &bfqg->stats;
++
++	if (blkg_rwstat_total(&stats->queued))
++		return;
++
++	/*
++	 * group is already marked empty. This can happen if bfqq got new
++	 * request in parent group and moved to this group while being added
++	 * to service tree. Just ignore the event and move on.
++	 */
++	if (bfqg_stats_empty(stats))
++		return;
++
++	stats->start_empty_time = sched_clock();
++	bfqg_stats_mark_empty(stats);
++}
++
++static void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
++{
++	struct bfqg_stats *stats = &bfqg->stats;
++
++	if (bfqg_stats_idling(stats)) {
++		unsigned long long now = sched_clock();
++
++		if (time_after64(now, stats->start_idle_time))
++			blkg_stat_add(&stats->idle_time,
++				      now - stats->start_idle_time);
++		bfqg_stats_clear_idling(stats);
++	}
++}
++
++static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
++{
++	struct bfqg_stats *stats = &bfqg->stats;
++
++	stats->start_idle_time = sched_clock();
++	bfqg_stats_mark_idling(stats);
++}
++
++static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
++{
++	struct bfqg_stats *stats = &bfqg->stats;
++
++	blkg_stat_add(&stats->avg_queue_size_sum,
++		      blkg_rwstat_total(&stats->queued));
++	blkg_stat_add(&stats->avg_queue_size_samples, 1);
++	bfqg_stats_update_group_wait_time(stats);
++}
++
++static struct blkcg_policy blkcg_policy_bfq;
++
++/*
++ * blk-cgroup policy-related handlers
++ * The following functions help in converting between blk-cgroup
++ * internal structures and BFQ-specific structures.
++ */
++
++static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
++{
++	return pd ? container_of(pd, struct bfq_group, pd) : NULL;
++}
++
++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
++{
++	return pd_to_blkg(&bfqg->pd);
++}
++
++static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
++{
++	struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq);
++	BUG_ON(!pd);
++	return pd_to_bfqg(pd);
++}
++
++/*
++ * bfq_group handlers
++ * The following functions help in navigating the bfq_group hierarchy
++ * by allowing to find the parent of a bfq_group or the bfq_group
++ * associated to a bfq_queue.
++ */
++
++static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
++{
++	struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
++
++	return pblkg ? blkg_to_bfqg(pblkg) : NULL;
++}
++
++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
++{
++	struct bfq_entity *group_entity = bfqq->entity.parent;
++
++	return group_entity ? container_of(group_entity, struct bfq_group,
++					   entity) :
++			      bfqq->bfqd->root_group;
++}
++
++/*
++ * The following two functions handle get and put of a bfq_group by
++ * wrapping the related blk-cgroup hooks.
++ */
++
++static void bfqg_get(struct bfq_group *bfqg)
++{
++	return blkg_get(bfqg_to_blkg(bfqg));
++}
++
++static void bfqg_put(struct bfq_group *bfqg)
++{
++	return blkg_put(bfqg_to_blkg(bfqg));
++}
++
++static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
++				     struct bfq_queue *bfqq,
++				     int rw)
++{
++	blkg_rwstat_add(&bfqg->stats.queued, rw, 1);
++	bfqg_stats_end_empty_time(&bfqg->stats);
++	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
++		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
++}
++
++static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, int rw)
++{
++	blkg_rwstat_add(&bfqg->stats.queued, rw, -1);
++}
++
++static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int rw)
++{
++	blkg_rwstat_add(&bfqg->stats.merged, rw, 1);
++}
++
++static void bfqg_stats_update_dispatch(struct bfq_group *bfqg,
++					      uint64_t bytes, int rw)
++{
++	blkg_stat_add(&bfqg->stats.sectors, bytes >> 9);
++	blkg_rwstat_add(&bfqg->stats.serviced, rw, 1);
++	blkg_rwstat_add(&bfqg->stats.service_bytes, rw, bytes);
++}
++
++static void bfqg_stats_update_completion(struct bfq_group *bfqg,
++			uint64_t start_time, uint64_t io_start_time, int rw)
++{
++	struct bfqg_stats *stats = &bfqg->stats;
++	unsigned long long now = sched_clock();
++
++	if (time_after64(now, io_start_time))
++		blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
++	if (time_after64(io_start_time, start_time))
++		blkg_rwstat_add(&stats->wait_time, rw,
++				io_start_time - start_time);
++}
++
++/* @stats = 0 */
++static void bfqg_stats_reset(struct bfqg_stats *stats)
++{
++	if (!stats)
++		return;
++
++	/* queued stats shouldn't be cleared */
++	blkg_rwstat_reset(&stats->service_bytes);
++	blkg_rwstat_reset(&stats->serviced);
++	blkg_rwstat_reset(&stats->merged);
++	blkg_rwstat_reset(&stats->service_time);
++	blkg_rwstat_reset(&stats->wait_time);
++	blkg_stat_reset(&stats->time);
++	blkg_stat_reset(&stats->unaccounted_time);
++	blkg_stat_reset(&stats->avg_queue_size_sum);
++	blkg_stat_reset(&stats->avg_queue_size_samples);
++	blkg_stat_reset(&stats->dequeue);
++	blkg_stat_reset(&stats->group_wait_time);
++	blkg_stat_reset(&stats->idle_time);
++	blkg_stat_reset(&stats->empty_time);
++}
++
++/* @to += @from */
++static void bfqg_stats_merge(struct bfqg_stats *to, struct bfqg_stats *from)
++{
++	if (!to || !from)
++		return;
++
++	/* queued stats shouldn't be cleared */
++	blkg_rwstat_add_aux(&to->service_bytes, &from->service_bytes);
++	blkg_rwstat_add_aux(&to->serviced, &from->serviced);
++	blkg_rwstat_add_aux(&to->merged, &from->merged);
++	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
++	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
++	blkg_stat_add_aux(&from->time, &from->time);
++	blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
++	blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
++	blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
++	blkg_stat_add_aux(&to->dequeue, &from->dequeue);
++	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
++	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
++	blkg_stat_add_aux(&to->empty_time, &from->empty_time);
++}
++
++/*
++ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors'
++ * recursive stats can still account for the amount used by this bfqg after
++ * it's gone.
++ */
++static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
++{
++	struct bfq_group *parent;
++
++	if (!bfqg) /* root_group */
++		return;
++
++	parent = bfqg_parent(bfqg);
++
++	lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
++
++	if (unlikely(!parent))
++		return;
++
++	bfqg_stats_merge(&parent->dead_stats, &bfqg->stats);
++	bfqg_stats_merge(&parent->dead_stats, &bfqg->dead_stats);
++	bfqg_stats_reset(&bfqg->stats);
++	bfqg_stats_reset(&bfqg->dead_stats);
++}
++
++static void bfq_init_entity(struct bfq_entity *entity,
++			    struct bfq_group *bfqg)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++
++	entity->weight = entity->new_weight;
++	entity->orig_weight = entity->new_weight;
++	if (bfqq) {
++		bfqq->ioprio = bfqq->new_ioprio;
++		bfqq->ioprio_class = bfqq->new_ioprio_class;
++		bfqg_get(bfqg);
++	}
++	entity->parent = bfqg->my_entity;
++	entity->sched_data = &bfqg->sched_data;
++}
++
++static void bfqg_stats_exit(struct bfqg_stats *stats)
++{
++	blkg_rwstat_exit(&stats->service_bytes);
++	blkg_rwstat_exit(&stats->serviced);
++	blkg_rwstat_exit(&stats->merged);
++	blkg_rwstat_exit(&stats->service_time);
++	blkg_rwstat_exit(&stats->wait_time);
++	blkg_rwstat_exit(&stats->queued);
++	blkg_stat_exit(&stats->sectors);
++	blkg_stat_exit(&stats->time);
++	blkg_stat_exit(&stats->unaccounted_time);
++	blkg_stat_exit(&stats->avg_queue_size_sum);
++	blkg_stat_exit(&stats->avg_queue_size_samples);
++	blkg_stat_exit(&stats->dequeue);
++	blkg_stat_exit(&stats->group_wait_time);
++	blkg_stat_exit(&stats->idle_time);
++	blkg_stat_exit(&stats->empty_time);
++}
++
++static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
++{
++	if (blkg_rwstat_init(&stats->service_bytes, gfp) ||
++	    blkg_rwstat_init(&stats->serviced, gfp) ||
++	    blkg_rwstat_init(&stats->merged, gfp) ||
++	    blkg_rwstat_init(&stats->service_time, gfp) ||
++	    blkg_rwstat_init(&stats->wait_time, gfp) ||
++	    blkg_rwstat_init(&stats->queued, gfp) ||
++	    blkg_stat_init(&stats->sectors, gfp) ||
++	    blkg_stat_init(&stats->time, gfp) ||
++	    blkg_stat_init(&stats->unaccounted_time, gfp) ||
++	    blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
++	    blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
++	    blkg_stat_init(&stats->dequeue, gfp) ||
++	    blkg_stat_init(&stats->group_wait_time, gfp) ||
++	    blkg_stat_init(&stats->idle_time, gfp) ||
++	    blkg_stat_init(&stats->empty_time, gfp)) {
++		bfqg_stats_exit(stats);
++		return -ENOMEM;
++	}
++
++	return 0;
++}
++
++static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
++ {
++	return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
++ }
++
++static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
++{
++	return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
++}
++
++static void bfq_cpd_init(struct blkcg_policy_data *cpd)
++{
++	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
++
++	d->weight = BFQ_DEFAULT_GRP_WEIGHT;
++}
++
++static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
++{
++	struct bfq_group *bfqg;
++
++	bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
++	if (!bfqg)
++		return NULL;
++
++	if (bfqg_stats_init(&bfqg->stats, gfp) ||
++	    bfqg_stats_init(&bfqg->dead_stats, gfp)) {
++		kfree(bfqg);
++		return NULL;
++	}
++
++	return &bfqg->pd;
++}
++
++static void bfq_group_set_parent(struct bfq_group *bfqg,
++					struct bfq_group *parent)
++{
++	struct bfq_entity *entity;
++
++	BUG_ON(!parent);
++	BUG_ON(!bfqg);
++	BUG_ON(bfqg == parent);
++
++	entity = &bfqg->entity;
++	entity->parent = parent->my_entity;
++	entity->sched_data = &parent->sched_data;
++}
++
++static void bfq_pd_init(struct blkg_policy_data *pd)
++{
++	struct blkcg_gq *blkg = pd_to_blkg(pd);
++	struct bfq_group *bfqg = blkg_to_bfqg(blkg);
++	struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
++	struct bfq_entity *entity = &bfqg->entity;
++	struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
++
++	entity->orig_weight = entity->weight = entity->new_weight = d->weight;
++	entity->my_sched_data = &bfqg->sched_data;
++	bfqg->my_entity = entity; /*
++				   * the root_group's will be set to NULL
++				   * in bfq_init_queue()
++				   */
++	bfqg->bfqd = bfqd;
++	bfqg->active_entities = 0;
++}
++
++static void bfq_pd_free(struct blkg_policy_data *pd)
++{
++	struct bfq_group *bfqg = pd_to_bfqg(pd);
++
++	bfqg_stats_exit(&bfqg->stats);
++	bfqg_stats_exit(&bfqg->dead_stats);
++
++	return kfree(bfqg);
++}
++
++/* offset delta from bfqg->stats to bfqg->dead_stats */
++static const int dead_stats_off_delta = offsetof(struct bfq_group, dead_stats) -
++					offsetof(struct bfq_group, stats);
++
++/* to be used by recursive prfill, sums live and dead stats recursively */
++static u64 bfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
++{
++	u64 sum = 0;
++
++	sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off);
++	sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq,
++				       off + dead_stats_off_delta);
++	return sum;
++}
++
++/* to be used by recursive prfill, sums live and dead rwstats recursively */
++static struct blkg_rwstat bfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
++						       int off)
++{
++	struct blkg_rwstat a, b;
++
++	a = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off);
++	b = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq,
++				      off + dead_stats_off_delta);
++	blkg_rwstat_add_aux(&a, &b);
++	return a;
++}
++
++static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
++{
++	struct bfq_group *bfqg = pd_to_bfqg(pd);
++
++	bfqg_stats_reset(&bfqg->stats);
++	bfqg_stats_reset(&bfqg->dead_stats);
++}
++
++static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
++					      struct blkcg *blkcg)
++{
++	struct request_queue *q = bfqd->queue;
++	struct bfq_group *bfqg = NULL, *parent;
++	struct bfq_entity *entity = NULL;
++
++	assert_spin_locked(bfqd->queue->queue_lock);
++
++	/* avoid lookup for the common case where there's no blkcg */
++	if (blkcg == &blkcg_root) {
++		bfqg = bfqd->root_group;
++	} else {
++		struct blkcg_gq *blkg;
++
++		blkg = blkg_lookup_create(blkcg, q);
++		if (!IS_ERR(blkg))
++			bfqg = blkg_to_bfqg(blkg);
++		else /* fallback to root_group */
++			bfqg = bfqd->root_group;
++	}
++
++	BUG_ON(!bfqg);
++
++	/*
++	 * Update chain of bfq_groups as we might be handling a leaf group
++	 * which, along with some of its relatives, has not been hooked yet
++	 * to the private hierarchy of BFQ.
++	 */
++	entity = &bfqg->entity;
++	for_each_entity(entity) {
++		bfqg = container_of(entity, struct bfq_group, entity);
++		BUG_ON(!bfqg);
++		if (bfqg != bfqd->root_group) {
++			parent = bfqg_parent(bfqg);
++			if (!parent)
++				parent = bfqd->root_group;
++			BUG_ON(!parent);
++			bfq_group_set_parent(bfqg, parent);
++		}
++	}
++
++	return bfqg;
++}
++
++/**
++ * bfq_bfqq_move - migrate @bfqq to @bfqg.
++ * @bfqd: queue descriptor.
++ * @bfqq: the queue to move.
++ * @entity: @bfqq's entity.
++ * @bfqg: the group to move to.
++ *
++ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
++ * it on the new one.  Avoid putting the entity on the old group idle tree.
++ *
++ * Must be called under the queue lock; the cgroup owning @bfqg must
++ * not disappear (by now this just means that we are called under
++ * rcu_read_lock()).
++ */
++static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++			  struct bfq_entity *entity, struct bfq_group *bfqg)
++{
++	int busy, resume;
++
++	busy = bfq_bfqq_busy(bfqq);
++	resume = !RB_EMPTY_ROOT(&bfqq->sort_list);
++
++	BUG_ON(resume && !entity->on_st);
++	BUG_ON(busy && !resume && entity->on_st &&
++	       bfqq != bfqd->in_service_queue);
++
++	if (busy) {
++		BUG_ON(atomic_read(&bfqq->ref) < 2);
++
++		if (!resume)
++			bfq_del_bfqq_busy(bfqd, bfqq, 0);
++		else
++			bfq_deactivate_bfqq(bfqd, bfqq, 0);
++	} else if (entity->on_st)
++		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
++	bfqg_put(bfqq_group(bfqq));
++
++	/*
++	 * Here we use a reference to bfqg.  We don't need a refcounter
++	 * as the cgroup reference will not be dropped, so that its
++	 * destroy() callback will not be invoked.
++	 */
++	entity->parent = bfqg->my_entity;
++	entity->sched_data = &bfqg->sched_data;
++	bfqg_get(bfqg);
++
++	if (busy) {
++		if (resume)
++			bfq_activate_bfqq(bfqd, bfqq);
++	}
++
++	if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
++		bfq_schedule_dispatch(bfqd);
++}
++
++/**
++ * __bfq_bic_change_cgroup - move @bic to @cgroup.
++ * @bfqd: the queue descriptor.
++ * @bic: the bic to move.
++ * @blkcg: the blk-cgroup to move to.
++ *
++ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
++ * has to make sure that the reference to cgroup is valid across the call.
++ *
++ * NOTE: an alternative approach might have been to store the current
++ * cgroup in bfqq and getting a reference to it, reducing the lookup
++ * time here, at the price of slightly more complex code.
++ */
++static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
++						struct bfq_io_cq *bic,
++						struct blkcg *blkcg)
++{
++	struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
++	struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
++	struct bfq_group *bfqg;
++	struct bfq_entity *entity;
++
++	lockdep_assert_held(bfqd->queue->queue_lock);
++
++	bfqg = bfq_find_alloc_group(bfqd, blkcg);
++	if (async_bfqq) {
++		entity = &async_bfqq->entity;
++
++		if (entity->sched_data != &bfqg->sched_data) {
++			bic_set_bfqq(bic, NULL, 0);
++			bfq_log_bfqq(bfqd, async_bfqq,
++				     "bic_change_group: %p %d",
++				     async_bfqq, atomic_read(&async_bfqq->ref));
++			bfq_put_queue(async_bfqq);
++		}
++	}
++
++	if (sync_bfqq) {
++		entity = &sync_bfqq->entity;
++		if (entity->sched_data != &bfqg->sched_data)
++			bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg);
++	}
++
++	return bfqg;
++}
++
++static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
++{
++	struct bfq_data *bfqd = bic_to_bfqd(bic);
++	struct blkcg *blkcg;
++	struct bfq_group *bfqg = NULL;
++	uint64_t id;
++
++	rcu_read_lock();
++	blkcg = bio_blkcg(bio);
++	id = blkcg->css.serial_nr;
++	rcu_read_unlock();
++
++	/*
++	 * Check whether blkcg has changed.  The condition may trigger
++	 * spuriously on a newly created cic but there's no harm.
++	 */
++	if (unlikely(!bfqd) || likely(bic->blkcg_id == id))
++		return;
++
++	bfqg = __bfq_bic_change_cgroup(bfqd, bic, blkcg);
++	BUG_ON(!bfqg);
++	bic->blkcg_id = id;
++}
++
++/**
++ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
++ * @st: the service tree being flushed.
++ */
++static void bfq_flush_idle_tree(struct bfq_service_tree *st)
++{
++	struct bfq_entity *entity = st->first_idle;
++
++	for (; entity ; entity = st->first_idle)
++		__bfq_deactivate_entity(entity, 0);
++}
++
++/**
++ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
++ * @bfqd: the device data structure with the root group.
++ * @entity: the entity to move.
++ */
++static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
++				     struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++
++	BUG_ON(!bfqq);
++	bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group);
++	return;
++}
++
++/**
++ * bfq_reparent_active_entities - move to the root group all active
++ *                                entities.
++ * @bfqd: the device data structure with the root group.
++ * @bfqg: the group to move from.
++ * @st: the service tree with the entities.
++ *
++ * Needs queue_lock to be taken and reference to be valid over the call.
++ */
++static void bfq_reparent_active_entities(struct bfq_data *bfqd,
++					 struct bfq_group *bfqg,
++					 struct bfq_service_tree *st)
++{
++	struct rb_root *active = &st->active;
++	struct bfq_entity *entity = NULL;
++
++	if (!RB_EMPTY_ROOT(&st->active))
++		entity = bfq_entity_of(rb_first(active));
++
++	for (; entity ; entity = bfq_entity_of(rb_first(active)))
++		bfq_reparent_leaf_entity(bfqd, entity);
++
++	if (bfqg->sched_data.in_service_entity)
++		bfq_reparent_leaf_entity(bfqd,
++			bfqg->sched_data.in_service_entity);
++
++	return;
++}
++
++/**
++ * bfq_destroy_group - destroy @bfqg.
++ * @bfqg: the group being destroyed.
++ *
++ * Destroy @bfqg, making sure that it is not referenced from its parent.
++ * blkio already grabs the queue_lock for us, so no need to use RCU-based magic
++ */
++static void bfq_pd_offline(struct blkg_policy_data *pd)
++{
++	struct bfq_service_tree *st;
++	struct bfq_group *bfqg;
++	struct bfq_data *bfqd;
++	struct bfq_entity *entity;
++	int i;
++
++	BUG_ON(!pd);
++	bfqg = pd_to_bfqg(pd);
++	BUG_ON(!bfqg);
++	bfqd = bfqg->bfqd;
++	BUG_ON(bfqd && !bfqd->root_group);
++
++	entity = bfqg->my_entity;
++
++	if (!entity) /* root group */
++		return;
++
++	/*
++	 * Empty all service_trees belonging to this group before
++	 * deactivating the group itself.
++	 */
++	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
++		BUG_ON(!bfqg->sched_data.service_tree);
++		st = bfqg->sched_data.service_tree + i;
++		/*
++		 * The idle tree may still contain bfq_queues belonging
++		 * to exited task because they never migrated to a different
++		 * cgroup from the one being destroyed now.  No one else
++		 * can access them so it's safe to act without any lock.
++		 */
++		bfq_flush_idle_tree(st);
++
++		/*
++		 * It may happen that some queues are still active
++		 * (busy) upon group destruction (if the corresponding
++		 * processes have been forced to terminate). We move
++		 * all the leaf entities corresponding to these queues
++		 * to the root_group.
++		 * Also, it may happen that the group has an entity
++		 * in service, which is disconnected from the active
++		 * tree: it must be moved, too.
++		 * There is no need to put the sync queues, as the
++		 * scheduler has taken no reference.
++		 */
++		bfq_reparent_active_entities(bfqd, bfqg, st);
++		BUG_ON(!RB_EMPTY_ROOT(&st->active));
++		BUG_ON(!RB_EMPTY_ROOT(&st->idle));
++	}
++	BUG_ON(bfqg->sched_data.next_in_service);
++	BUG_ON(bfqg->sched_data.in_service_entity);
++
++	__bfq_deactivate_entity(entity, 0);
++	bfq_put_async_queues(bfqd, bfqg);
++	BUG_ON(entity->tree);
++
++	bfqg_stats_xfer_dead(bfqg);
++}
++
++static void bfq_end_wr_async(struct bfq_data *bfqd)
++{
++	struct blkcg_gq *blkg;
++
++	list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
++		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
++
++		bfq_end_wr_async_queues(bfqd, bfqg);
++	}
++	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
++}
++
++static u64 bfqio_cgroup_weight_read(struct cgroup_subsys_state *css,
++				       struct cftype *cftype)
++{
++	struct blkcg *blkcg = css_to_blkcg(css);
++	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
++	int ret = -EINVAL;
++
++	spin_lock_irq(&blkcg->lock);
++	ret = bfqgd->weight;
++	spin_unlock_irq(&blkcg->lock);
++
++	return ret;
++}
++
++static int bfqio_cgroup_weight_read_dfl(struct seq_file *sf, void *v)
++{
++	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
++	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
++
++	spin_lock_irq(&blkcg->lock);
++	seq_printf(sf, "%u\n", bfqgd->weight);
++	spin_unlock_irq(&blkcg->lock);
++
++	return 0;
++}
++
++static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css,
++					struct cftype *cftype,
++					u64 val)
++{
++	struct blkcg *blkcg = css_to_blkcg(css);
++	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
++	struct blkcg_gq *blkg;
++	int ret = -EINVAL;
++
++	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
++		return ret;
++
++	ret = 0;
++	spin_lock_irq(&blkcg->lock);
++	bfqgd->weight = (unsigned short)val;
++	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
++		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
++		if (!bfqg)
++			continue;
++		/*
++		 * Setting the prio_changed flag of the entity
++		 * to 1 with new_weight == weight would re-set
++		 * the value of the weight to its ioprio mapping.
++		 * Set the flag only if necessary.
++		 */
++		if ((unsigned short)val != bfqg->entity.new_weight) {
++			bfqg->entity.new_weight = (unsigned short)val;
++			/*
++			 * Make sure that the above new value has been
++			 * stored in bfqg->entity.new_weight before
++			 * setting the prio_changed flag. In fact,
++			 * this flag may be read asynchronously (in
++			 * critical sections protected by a different
++			 * lock than that held here), and finding this
++			 * flag set may cause the execution of the code
++			 * for updating parameters whose value may
++			 * depend also on bfqg->entity.new_weight (in
++			 * __bfq_entity_update_weight_prio).
++			 * This barrier makes sure that the new value
++			 * of bfqg->entity.new_weight is correctly
++			 * seen in that code.
++			 */
++			smp_wmb();
++			bfqg->entity.prio_changed = 1;
++		}
++	}
++	spin_unlock_irq(&blkcg->lock);
++
++	return ret;
++}
++
++static ssize_t bfqio_cgroup_weight_write_dfl(struct kernfs_open_file *of,
++					     char *buf, size_t nbytes,
++					     loff_t off)
++{
++	/* First unsigned long found in the file is used */
++	return bfqio_cgroup_weight_write(of_css(of), NULL,
++					 simple_strtoull(strim(buf), NULL, 0));
++}
++
++static int bfqg_print_stat(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
++			  &blkcg_policy_bfq, seq_cft(sf)->private, false);
++	return 0;
++}
++
++static int bfqg_print_rwstat(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
++			  &blkcg_policy_bfq, seq_cft(sf)->private, true);
++	return 0;
++}
++
++static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
++				      struct blkg_policy_data *pd, int off)
++{
++	u64 sum = bfqg_stat_pd_recursive_sum(pd, off);
++
++	return __blkg_prfill_u64(sf, pd, sum);
++}
++
++static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
++					struct blkg_policy_data *pd, int off)
++{
++	struct blkg_rwstat sum = bfqg_rwstat_pd_recursive_sum(pd, off);
++
++	return __blkg_prfill_rwstat(sf, pd, &sum);
++}
++
++static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
++			  bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
++			  seq_cft(sf)->private, false);
++	return 0;
++}
++
++static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
++			  bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
++			  seq_cft(sf)->private, true);
++	return 0;
++}
++
++static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
++				      struct blkg_policy_data *pd, int off)
++{
++	struct bfq_group *bfqg = pd_to_bfqg(pd);
++	u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
++	u64 v = 0;
++
++	if (samples) {
++		v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
++		v = div64_u64(v, samples);
++	}
++	__blkg_prfill_u64(sf, pd, v);
++	return 0;
++}
++
++/* print avg_queue_size */
++static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
++			  bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
++			  0, false);
++	return 0;
++}
++
++static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
++{
++	int ret;
++
++	ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
++	if (ret)
++		return NULL;
++
++        return blkg_to_bfqg(bfqd->queue->root_blkg);
++}
++
++static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
++{
++        struct bfq_group_data *bgd;
++
++        bgd = kzalloc(sizeof(*bgd), GFP_KERNEL);
++        if (!bgd)
++                return NULL;
++        return &bgd->pd;
++}
++
++static void bfq_cpd_free(struct blkcg_policy_data *cpd)
++{
++        kfree(cpd_to_bfqgd(cpd));
++}
++
++static struct cftype bfqio_files_dfl[] = {
++	{
++		.name = "weight",
++		.flags = CFTYPE_NOT_ON_ROOT,
++		.seq_show = bfqio_cgroup_weight_read_dfl,
++		.write = bfqio_cgroup_weight_write_dfl,
++	},
++	{} /* terminate */
++};
++
++static struct cftype bfqio_files[] = {
++	{
++		.name = "bfq.weight",
++		.read_u64 = bfqio_cgroup_weight_read,
++		.write_u64 = bfqio_cgroup_weight_write,
++	},
++	/* statistics, cover only the tasks in the bfqg */
++	{
++		.name = "bfq.time",
++		.private = offsetof(struct bfq_group, stats.time),
++		.seq_show = bfqg_print_stat,
++	},
++	{
++		.name = "bfq.sectors",
++		.private = offsetof(struct bfq_group, stats.sectors),
++		.seq_show = bfqg_print_stat,
++	},
++	{
++		.name = "bfq.io_service_bytes",
++		.private = offsetof(struct bfq_group, stats.service_bytes),
++		.seq_show = bfqg_print_rwstat,
++	},
++	{
++		.name = "bfq.io_serviced",
++		.private = offsetof(struct bfq_group, stats.serviced),
++		.seq_show = bfqg_print_rwstat,
++	},
++	{
++		.name = "bfq.io_service_time",
++		.private = offsetof(struct bfq_group, stats.service_time),
++		.seq_show = bfqg_print_rwstat,
++	},
++	{
++		.name = "bfq.io_wait_time",
++		.private = offsetof(struct bfq_group, stats.wait_time),
++		.seq_show = bfqg_print_rwstat,
++	},
++	{
++		.name = "bfq.io_merged",
++		.private = offsetof(struct bfq_group, stats.merged),
++		.seq_show = bfqg_print_rwstat,
++	},
++	{
++		.name = "bfq.io_queued",
++		.private = offsetof(struct bfq_group, stats.queued),
++		.seq_show = bfqg_print_rwstat,
++	},
++
++	/* the same statictics which cover the bfqg and its descendants */
++	{
++		.name = "bfq.time_recursive",
++		.private = offsetof(struct bfq_group, stats.time),
++		.seq_show = bfqg_print_stat_recursive,
++	},
++	{
++		.name = "bfq.sectors_recursive",
++		.private = offsetof(struct bfq_group, stats.sectors),
++		.seq_show = bfqg_print_stat_recursive,
++	},
++	{
++		.name = "bfq.io_service_bytes_recursive",
++		.private = offsetof(struct bfq_group, stats.service_bytes),
++		.seq_show = bfqg_print_rwstat_recursive,
++	},
++	{
++		.name = "bfq.io_serviced_recursive",
++		.private = offsetof(struct bfq_group, stats.serviced),
++		.seq_show = bfqg_print_rwstat_recursive,
++	},
++	{
++		.name = "bfq.io_service_time_recursive",
++		.private = offsetof(struct bfq_group, stats.service_time),
++		.seq_show = bfqg_print_rwstat_recursive,
++	},
++	{
++		.name = "bfq.io_wait_time_recursive",
++		.private = offsetof(struct bfq_group, stats.wait_time),
++		.seq_show = bfqg_print_rwstat_recursive,
++	},
++	{
++		.name = "bfq.io_merged_recursive",
++		.private = offsetof(struct bfq_group, stats.merged),
++		.seq_show = bfqg_print_rwstat_recursive,
++	},
++	{
++		.name = "bfq.io_queued_recursive",
++		.private = offsetof(struct bfq_group, stats.queued),
++		.seq_show = bfqg_print_rwstat_recursive,
++	},
++	{
++		.name = "bfq.avg_queue_size",
++		.seq_show = bfqg_print_avg_queue_size,
++	},
++	{
++		.name = "bfq.group_wait_time",
++		.private = offsetof(struct bfq_group, stats.group_wait_time),
++		.seq_show = bfqg_print_stat,
++	},
++	{
++		.name = "bfq.idle_time",
++		.private = offsetof(struct bfq_group, stats.idle_time),
++		.seq_show = bfqg_print_stat,
++	},
++	{
++		.name = "bfq.empty_time",
++		.private = offsetof(struct bfq_group, stats.empty_time),
++		.seq_show = bfqg_print_stat,
++	},
++	{
++		.name = "bfq.dequeue",
++		.private = offsetof(struct bfq_group, stats.dequeue),
++		.seq_show = bfqg_print_stat,
++	},
++	{
++		.name = "bfq.unaccounted_time",
++		.private = offsetof(struct bfq_group, stats.unaccounted_time),
++		.seq_show = bfqg_print_stat,
++	},
++	{ }	/* terminate */
++};
++
++static struct blkcg_policy blkcg_policy_bfq = {
++       .dfl_cftypes            = bfqio_files_dfl,
++       .legacy_cftypes         = bfqio_files,
++
++       .pd_alloc_fn            = bfq_pd_alloc,
++       .pd_init_fn             = bfq_pd_init,
++       .pd_offline_fn          = bfq_pd_offline,
++       .pd_free_fn             = bfq_pd_free,
++       .pd_reset_stats_fn      = bfq_pd_reset_stats,
++
++       .cpd_alloc_fn           = bfq_cpd_alloc,
++       .cpd_init_fn            = bfq_cpd_init,
++       .cpd_bind_fn	       = bfq_cpd_init,
++       .cpd_free_fn            = bfq_cpd_free,
++
++};
++
++#else
++
++static void bfq_init_entity(struct bfq_entity *entity,
++			    struct bfq_group *bfqg)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	entity->weight = entity->new_weight;
++	entity->orig_weight = entity->new_weight;
++	if (bfqq) {
++		bfqq->ioprio = bfqq->new_ioprio;
++		bfqq->ioprio_class = bfqq->new_ioprio_class;
++	}
++	entity->sched_data = &bfqg->sched_data;
++}
++
++static struct bfq_group *
++bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
++{
++	struct bfq_data *bfqd = bic_to_bfqd(bic);
++	return bfqd->root_group;
++}
++
++static void bfq_bfqq_move(struct bfq_data *bfqd,
++			  struct bfq_queue *bfqq,
++			  struct bfq_entity *entity,
++			  struct bfq_group *bfqg)
++{
++}
++
++static void bfq_end_wr_async(struct bfq_data *bfqd)
++{
++	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
++}
++
++static void bfq_disconnect_groups(struct bfq_data *bfqd)
++{
++	bfq_put_async_queues(bfqd, bfqd->root_group);
++}
++
++static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
++                                              struct blkcg *blkcg)
++{
++	return bfqd->root_group;
++}
++
++static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
++{
++	struct bfq_group *bfqg;
++	int i;
++
++	bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
++	if (!bfqg)
++		return NULL;
++
++	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
++		bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
++
++	return bfqg;
++}
++#endif
+diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c
+new file mode 100644
+index 0000000..fb7bb8f
+--- /dev/null
++++ b/block/bfq-ioc.c
+@@ -0,0 +1,36 @@
++/*
++ * BFQ: I/O context handling.
++ *
++ * Based on ideas and code from CFQ:
++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
++ *
++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
++ *		      Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ */
++
++/**
++ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
++ * @icq: the iocontext queue.
++ */
++static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
++{
++	/* bic->icq is the first member, %NULL will convert to %NULL */
++	return container_of(icq, struct bfq_io_cq, icq);
++}
++
++/**
++ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
++ * @bfqd: the lookup key.
++ * @ioc: the io_context of the process doing I/O.
++ *
++ * Queue lock must be held.
++ */
++static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
++					struct io_context *ioc)
++{
++	if (ioc)
++		return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
++	return NULL;
++}
+diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
+new file mode 100644
+index 0000000..f9787a6
+--- /dev/null
++++ b/block/bfq-iosched.c
+@@ -0,0 +1,3754 @@
++/*
++ * Budget Fair Queueing (BFQ) disk scheduler.
++ *
++ * Based on ideas and code from CFQ:
++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
++ *
++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
++ *		      Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
++ * file.
++ *
++ * BFQ is a proportional-share storage-I/O scheduling algorithm based on
++ * the slice-by-slice service scheme of CFQ. But BFQ assigns budgets,
++ * measured in number of sectors, to processes instead of time slices. The
++ * device is not granted to the in-service process for a given time slice,
++ * but until it has exhausted its assigned budget. This change from the time
++ * to the service domain allows BFQ to distribute the device throughput
++ * among processes as desired, without any distortion due to ZBR, workload
++ * fluctuations or other factors. BFQ uses an ad hoc internal scheduler,
++ * called B-WF2Q+, to schedule processes according to their budgets. More
++ * precisely, BFQ schedules queues associated to processes. Thanks to the
++ * accurate policy of B-WF2Q+, BFQ can afford to assign high budgets to
++ * I/O-bound processes issuing sequential requests (to boost the
++ * throughput), and yet guarantee a low latency to interactive and soft
++ * real-time applications.
++ *
++ * BFQ is described in [1], where also a reference to the initial, more
++ * theoretical paper on BFQ can be found. The interested reader can find
++ * in the latter paper full details on the main algorithm, as well as
++ * formulas of the guarantees and formal proofs of all the properties.
++ * With respect to the version of BFQ presented in these papers, this
++ * implementation adds a few more heuristics, such as the one that
++ * guarantees a low latency to soft real-time applications, and a
++ * hierarchical extension based on H-WF2Q+.
++ *
++ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
++ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
++ * complexity derives from the one introduced with EEVDF in [3].
++ *
++ * [1] P. Valente and M. Andreolini, ``Improving Application Responsiveness
++ *     with the BFQ Disk I/O Scheduler'',
++ *     Proceedings of the 5th Annual International Systems and Storage
++ *     Conference (SYSTOR '12), June 2012.
++ *
++ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
++ *
++ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
++ *     Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
++ *     Oct 1997.
++ *
++ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
++ *
++ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
++ *     First: A Flexible and Accurate Mechanism for Proportional Share
++ *     Resource Allocation,'' technical report.
++ *
++ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
++ */
++#include <linux/module.h>
++#include <linux/slab.h>
++#include <linux/blkdev.h>
++#include <linux/cgroup.h>
++#include <linux/elevator.h>
++#include <linux/jiffies.h>
++#include <linux/rbtree.h>
++#include <linux/ioprio.h>
++#include "bfq.h"
++#include "blk.h"
++
++/* Expiration time of sync (0) and async (1) requests, in jiffies. */
++static const int bfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
++
++/* Maximum backwards seek, in KiB. */
++static const int bfq_back_max = 16 * 1024;
++
++/* Penalty of a backwards seek, in number of sectors. */
++static const int bfq_back_penalty = 2;
++
++/* Idling period duration, in jiffies. */
++static int bfq_slice_idle = HZ / 125;
++
++/* Minimum number of assigned budgets for which stats are safe to compute. */
++static const int bfq_stats_min_budgets = 194;
++
++/* Default maximum budget values, in sectors and number of requests. */
++static const int bfq_default_max_budget = 16 * 1024;
++static const int bfq_max_budget_async_rq = 4;
++
++/*
++ * Async to sync throughput distribution is controlled as follows:
++ * when an async request is served, the entity is charged the number
++ * of sectors of the request, multiplied by the factor below
++ */
++static const int bfq_async_charge_factor = 10;
++
++/* Default timeout values, in jiffies, approximating CFQ defaults. */
++static const int bfq_timeout_sync = HZ / 8;
++static int bfq_timeout_async = HZ / 25;
++
++struct kmem_cache *bfq_pool;
++
++/* Below this threshold (in ms), we consider thinktime immediate. */
++#define BFQ_MIN_TT		2
++
++/* hw_tag detection: parallel requests threshold and min samples needed. */
++#define BFQ_HW_QUEUE_THRESHOLD	4
++#define BFQ_HW_QUEUE_SAMPLES	32
++
++#define BFQQ_SEEK_THR	 (sector_t)(8 * 1024)
++#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR)
++
++/* Min samples used for peak rate estimation (for autotuning). */
++#define BFQ_PEAK_RATE_SAMPLES	32
++
++/* Shift used for peak rate fixed precision calculations. */
++#define BFQ_RATE_SHIFT		16
++
++/*
++ * By default, BFQ computes the duration of the weight raising for
++ * interactive applications automatically, using the following formula:
++ * duration = (R / r) * T, where r is the peak rate of the device, and
++ * R and T are two reference parameters.
++ * In particular, R is the peak rate of the reference device (see below),
++ * and T is a reference time: given the systems that are likely to be
++ * installed on the reference device according to its speed class, T is
++ * about the maximum time needed, under BFQ and while reading two files in
++ * parallel, to load typical large applications on these systems.
++ * In practice, the slower/faster the device at hand is, the more/less it
++ * takes to load applications with respect to the reference device.
++ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
++ * applications.
++ *
++ * BFQ uses four different reference pairs (R, T), depending on:
++ * . whether the device is rotational or non-rotational;
++ * . whether the device is slow, such as old or portable HDDs, as well as
++ *   SD cards, or fast, such as newer HDDs and SSDs.
++ *
++ * The device's speed class is dynamically (re)detected in
++ * bfq_update_peak_rate() every time the estimated peak rate is updated.
++ *
++ * In the following definitions, R_slow[0]/R_fast[0] and T_slow[0]/T_fast[0]
++ * are the reference values for a slow/fast rotational device, whereas
++ * R_slow[1]/R_fast[1] and T_slow[1]/T_fast[1] are the reference values for
++ * a slow/fast non-rotational device. Finally, device_speed_thresh are the
++ * thresholds used to switch between speed classes.
++ * Both the reference peak rates and the thresholds are measured in
++ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
++ */
++static int R_slow[2] = {1536, 10752};
++static int R_fast[2] = {17415, 34791};
++/*
++ * To improve readability, a conversion function is used to initialize the
++ * following arrays, which entails that they can be initialized only in a
++ * function.
++ */
++static int T_slow[2];
++static int T_fast[2];
++static int device_speed_thresh[2];
++
++#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
++				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
++
++#define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
++#define RQ_BFQQ(rq)		((rq)->elv.priv[1])
++
++static void bfq_schedule_dispatch(struct bfq_data *bfqd);
++
++#include "bfq-ioc.c"
++#include "bfq-sched.c"
++#include "bfq-cgroup.c"
++
++#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
++#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
++
++#define bfq_sample_valid(samples)	((samples) > 80)
++
++/*
++ * We regard a request as SYNC, if either it's a read or has the SYNC bit
++ * set (in which case it could also be a direct WRITE).
++ */
++static int bfq_bio_sync(struct bio *bio)
++{
++	if (bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC))
++		return 1;
++
++	return 0;
++}
++
++/*
++ * Scheduler run of queue, if there are requests pending and no one in the
++ * driver that will restart queueing.
++ */
++static void bfq_schedule_dispatch(struct bfq_data *bfqd)
++{
++	if (bfqd->queued != 0) {
++		bfq_log(bfqd, "schedule dispatch");
++		kblockd_schedule_work(&bfqd->unplug_work);
++	}
++}
++
++/*
++ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
++ * We choose the request that is closesr to the head right now.  Distance
++ * behind the head is penalized and only allowed to a certain extent.
++ */
++static struct request *bfq_choose_req(struct bfq_data *bfqd,
++				      struct request *rq1,
++				      struct request *rq2,
++				      sector_t last)
++{
++	sector_t s1, s2, d1 = 0, d2 = 0;
++	unsigned long back_max;
++#define BFQ_RQ1_WRAP	0x01 /* request 1 wraps */
++#define BFQ_RQ2_WRAP	0x02 /* request 2 wraps */
++	unsigned wrap = 0; /* bit mask: requests behind the disk head? */
++
++	if (!rq1 || rq1 == rq2)
++		return rq2;
++	if (!rq2)
++		return rq1;
++
++	if (rq_is_sync(rq1) && !rq_is_sync(rq2))
++		return rq1;
++	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
++		return rq2;
++	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
++		return rq1;
++	else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
++		return rq2;
++
++	s1 = blk_rq_pos(rq1);
++	s2 = blk_rq_pos(rq2);
++
++	/*
++	 * By definition, 1KiB is 2 sectors.
++	 */
++	back_max = bfqd->bfq_back_max * 2;
++
++	/*
++	 * Strict one way elevator _except_ in the case where we allow
++	 * short backward seeks which are biased as twice the cost of a
++	 * similar forward seek.
++	 */
++	if (s1 >= last)
++		d1 = s1 - last;
++	else if (s1 + back_max >= last)
++		d1 = (last - s1) * bfqd->bfq_back_penalty;
++	else
++		wrap |= BFQ_RQ1_WRAP;
++
++	if (s2 >= last)
++		d2 = s2 - last;
++	else if (s2 + back_max >= last)
++		d2 = (last - s2) * bfqd->bfq_back_penalty;
++	else
++		wrap |= BFQ_RQ2_WRAP;
++
++	/* Found required data */
++
++	/*
++	 * By doing switch() on the bit mask "wrap" we avoid having to
++	 * check two variables for all permutations: --> faster!
++	 */
++	switch (wrap) {
++	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
++		if (d1 < d2)
++			return rq1;
++		else if (d2 < d1)
++			return rq2;
++		else {
++			if (s1 >= s2)
++				return rq1;
++			else
++				return rq2;
++		}
++
++	case BFQ_RQ2_WRAP:
++		return rq1;
++	case BFQ_RQ1_WRAP:
++		return rq2;
++	case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
++	default:
++		/*
++		 * Since both rqs are wrapped,
++		 * start with the one that's further behind head
++		 * (--> only *one* back seek required),
++		 * since back seek takes more time than forward.
++		 */
++		if (s1 <= s2)
++			return rq1;
++		else
++			return rq2;
++	}
++}
++
++/*
++ * Tell whether there are active queues or groups with differentiated weights.
++ */
++static bool bfq_differentiated_weights(struct bfq_data *bfqd)
++{
++	/*
++	 * For weights to differ, at least one of the trees must contain
++	 * at least two nodes.
++	 */
++	return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
++		(bfqd->queue_weights_tree.rb_node->rb_left ||
++		 bfqd->queue_weights_tree.rb_node->rb_right)
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	       ) ||
++	       (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
++		(bfqd->group_weights_tree.rb_node->rb_left ||
++		 bfqd->group_weights_tree.rb_node->rb_right)
++#endif
++	       );
++}
++
++/*
++ * The following function returns true if every queue must receive the
++ * same share of the throughput (this condition is used when deciding
++ * whether idling may be disabled, see the comments in the function
++ * bfq_bfqq_may_idle()).
++ *
++ * Such a scenario occurs when:
++ * 1) all active queues have the same weight,
++ * 2) all active groups at the same level in the groups tree have the same
++ *    weight,
++ * 3) all active groups at the same level in the groups tree have the same
++ *    number of children.
++ *
++ * Unfortunately, keeping the necessary state for evaluating exactly the
++ * above symmetry conditions would be quite complex and time-consuming.
++ * Therefore this function evaluates, instead, the following stronger
++ * sub-conditions, for which it is much easier to maintain the needed
++ * state:
++ * 1) all active queues have the same weight,
++ * 2) all active groups have the same weight,
++ * 3) all active groups have at most one active child each.
++ * In particular, the last two conditions are always true if hierarchical
++ * support and the cgroups interface are not enabled, thus no state needs
++ * to be maintained in this case.
++ */
++static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
++{
++	return
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		!bfqd->active_numerous_groups &&
++#endif
++		!bfq_differentiated_weights(bfqd);
++}
++
++/*
++ * If the weight-counter tree passed as input contains no counter for
++ * the weight of the input entity, then add that counter; otherwise just
++ * increment the existing counter.
++ *
++ * Note that weight-counter trees contain few nodes in mostly symmetric
++ * scenarios. For example, if all queues have the same weight, then the
++ * weight-counter tree for the queues may contain at most one node.
++ * This holds even if low_latency is on, because weight-raised queues
++ * are not inserted in the tree.
++ * In most scenarios, the rate at which nodes are created/destroyed
++ * should be low too.
++ */
++static void bfq_weights_tree_add(struct bfq_data *bfqd,
++				 struct bfq_entity *entity,
++				 struct rb_root *root)
++{
++	struct rb_node **new = &(root->rb_node), *parent = NULL;
++
++	/*
++	 * Do not insert if the entity is already associated with a
++	 * counter, which happens if:
++	 *   1) the entity is associated with a queue,
++	 *   2) a request arrival has caused the queue to become both
++	 *      non-weight-raised, and hence change its weight, and
++	 *      backlogged; in this respect, each of the two events
++	 *      causes an invocation of this function,
++	 *   3) this is the invocation of this function caused by the
++	 *      second event. This second invocation is actually useless,
++	 *      and we handle this fact by exiting immediately. More
++	 *      efficient or clearer solutions might possibly be adopted.
++	 */
++	if (entity->weight_counter)
++		return;
++
++	while (*new) {
++		struct bfq_weight_counter *__counter = container_of(*new,
++						struct bfq_weight_counter,
++						weights_node);
++		parent = *new;
++
++		if (entity->weight == __counter->weight) {
++			entity->weight_counter = __counter;
++			goto inc_counter;
++		}
++		if (entity->weight < __counter->weight)
++			new = &((*new)->rb_left);
++		else
++			new = &((*new)->rb_right);
++	}
++
++	entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
++					 GFP_ATOMIC);
++	entity->weight_counter->weight = entity->weight;
++	rb_link_node(&entity->weight_counter->weights_node, parent, new);
++	rb_insert_color(&entity->weight_counter->weights_node, root);
++
++inc_counter:
++	entity->weight_counter->num_active++;
++}
++
++/*
++ * Decrement the weight counter associated with the entity, and, if the
++ * counter reaches 0, remove the counter from the tree.
++ * See the comments to the function bfq_weights_tree_add() for considerations
++ * about overhead.
++ */
++static void bfq_weights_tree_remove(struct bfq_data *bfqd,
++				    struct bfq_entity *entity,
++				    struct rb_root *root)
++{
++	if (!entity->weight_counter)
++		return;
++
++	BUG_ON(RB_EMPTY_ROOT(root));
++	BUG_ON(entity->weight_counter->weight != entity->weight);
++
++	BUG_ON(!entity->weight_counter->num_active);
++	entity->weight_counter->num_active--;
++	if (entity->weight_counter->num_active > 0)
++		goto reset_entity_pointer;
++
++	rb_erase(&entity->weight_counter->weights_node, root);
++	kfree(entity->weight_counter);
++
++reset_entity_pointer:
++	entity->weight_counter = NULL;
++}
++
++static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
++					struct bfq_queue *bfqq,
++					struct request *last)
++{
++	struct rb_node *rbnext = rb_next(&last->rb_node);
++	struct rb_node *rbprev = rb_prev(&last->rb_node);
++	struct request *next = NULL, *prev = NULL;
++
++	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
++
++	if (rbprev)
++		prev = rb_entry_rq(rbprev);
++
++	if (rbnext)
++		next = rb_entry_rq(rbnext);
++	else {
++		rbnext = rb_first(&bfqq->sort_list);
++		if (rbnext && rbnext != &last->rb_node)
++			next = rb_entry_rq(rbnext);
++	}
++
++	return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
++}
++
++/* see the definition of bfq_async_charge_factor for details */
++static unsigned long bfq_serv_to_charge(struct request *rq,
++					struct bfq_queue *bfqq)
++{
++	return blk_rq_sectors(rq) *
++		(1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) *
++		bfq_async_charge_factor));
++}
++
++/**
++ * bfq_updated_next_req - update the queue after a new next_rq selection.
++ * @bfqd: the device data the queue belongs to.
++ * @bfqq: the queue to update.
++ *
++ * If the first request of a queue changes we make sure that the queue
++ * has enough budget to serve at least its first request (if the
++ * request has grown).  We do this because if the queue has not enough
++ * budget for its first request, it has to go through two dispatch
++ * rounds to actually get it dispatched.
++ */
++static void bfq_updated_next_req(struct bfq_data *bfqd,
++				 struct bfq_queue *bfqq)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
++	struct request *next_rq = bfqq->next_rq;
++	unsigned long new_budget;
++
++	if (!next_rq)
++		return;
++
++	if (bfqq == bfqd->in_service_queue)
++		/*
++		 * In order not to break guarantees, budgets cannot be
++		 * changed after an entity has been selected.
++		 */
++		return;
++
++	BUG_ON(entity->tree != &st->active);
++	BUG_ON(entity == entity->sched_data->in_service_entity);
++
++	new_budget = max_t(unsigned long, bfqq->max_budget,
++			   bfq_serv_to_charge(next_rq, bfqq));
++	if (entity->budget != new_budget) {
++		entity->budget = new_budget;
++		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
++					 new_budget);
++		bfq_activate_bfqq(bfqd, bfqq);
++	}
++}
++
++static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
++{
++	u64 dur;
++
++	if (bfqd->bfq_wr_max_time > 0)
++		return bfqd->bfq_wr_max_time;
++
++	dur = bfqd->RT_prod;
++	do_div(dur, bfqd->peak_rate);
++
++	return dur;
++}
++
++/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
++static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	struct bfq_queue *item;
++	struct hlist_node *n;
++
++	hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
++		hlist_del_init(&item->burst_list_node);
++	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
++	bfqd->burst_size = 1;
++}
++
++/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
++static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	/* Increment burst size to take into account also bfqq */
++	bfqd->burst_size++;
++
++	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
++		struct bfq_queue *pos, *bfqq_item;
++		struct hlist_node *n;
++
++		/*
++		 * Enough queues have been activated shortly after each
++		 * other to consider this burst as large.
++		 */
++		bfqd->large_burst = true;
++
++		/*
++		 * We can now mark all queues in the burst list as
++		 * belonging to a large burst.
++		 */
++		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
++				     burst_list_node)
++		        bfq_mark_bfqq_in_large_burst(bfqq_item);
++		bfq_mark_bfqq_in_large_burst(bfqq);
++
++		/*
++		 * From now on, and until the current burst finishes, any
++		 * new queue being activated shortly after the last queue
++		 * was inserted in the burst can be immediately marked as
++		 * belonging to a large burst. So the burst list is not
++		 * needed any more. Remove it.
++		 */
++		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
++					  burst_list_node)
++			hlist_del_init(&pos->burst_list_node);
++	} else /* burst not yet large: add bfqq to the burst list */
++		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
++}
++
++/*
++ * If many queues happen to become active shortly after each other, then,
++ * to help the processes associated to these queues get their job done as
++ * soon as possible, it is usually better to not grant either weight-raising
++ * or device idling to these queues. In this comment we describe, firstly,
++ * the reasons why this fact holds, and, secondly, the next function, which
++ * implements the main steps needed to properly mark these queues so that
++ * they can then be treated in a different way.
++ *
++ * As for the terminology, we say that a queue becomes active, i.e.,
++ * switches from idle to backlogged, either when it is created (as a
++ * consequence of the arrival of an I/O request), or, if already existing,
++ * when a new request for the queue arrives while the queue is idle.
++ * Bursts of activations, i.e., activations of different queues occurring
++ * shortly after each other, are typically caused by services or applications
++ * that spawn or reactivate many parallel threads/processes. Examples are
++ * systemd during boot or git grep.
++ *
++ * These services or applications benefit mostly from a high throughput:
++ * the quicker the requests of the activated queues are cumulatively served,
++ * the sooner the target job of these queues gets completed. As a consequence,
++ * weight-raising any of these queues, which also implies idling the device
++ * for it, is almost always counterproductive: in most cases it just lowers
++ * throughput.
++ *
++ * On the other hand, a burst of activations may be also caused by the start
++ * of an application that does not consist in a lot of parallel I/O-bound
++ * threads. In fact, with a complex application, the burst may be just a
++ * consequence of the fact that several processes need to be executed to
++ * start-up the application. To start an application as quickly as possible,
++ * the best thing to do is to privilege the I/O related to the application
++ * with respect to all other I/O. Therefore, the best strategy to start as
++ * quickly as possible an application that causes a burst of activations is
++ * to weight-raise all the queues activated during the burst. This is the
++ * exact opposite of the best strategy for the other type of bursts.
++ *
++ * In the end, to take the best action for each of the two cases, the two
++ * types of bursts need to be distinguished. Fortunately, this seems
++ * relatively easy to do, by looking at the sizes of the bursts. In
++ * particular, we found a threshold such that bursts with a larger size
++ * than that threshold are apparently caused only by services or commands
++ * such as systemd or git grep. For brevity, hereafter we call just 'large'
++ * these bursts. BFQ *does not* weight-raise queues whose activations occur
++ * in a large burst. In addition, for each of these queues BFQ performs or
++ * does not perform idling depending on which choice boosts the throughput
++ * most. The exact choice depends on the device and request pattern at
++ * hand.
++ *
++ * Turning back to the next function, it implements all the steps needed
++ * to detect the occurrence of a large burst and to properly mark all the
++ * queues belonging to it (so that they can then be treated in a different
++ * way). This goal is achieved by maintaining a special "burst list" that
++ * holds, temporarily, the queues that belong to the burst in progress. The
++ * list is then used to mark these queues as belonging to a large burst if
++ * the burst does become large. The main steps are the following.
++ *
++ * . when the very first queue is activated, the queue is inserted into the
++ *   list (as it could be the first queue in a possible burst)
++ *
++ * . if the current burst has not yet become large, and a queue Q that does
++ *   not yet belong to the burst is activated shortly after the last time
++ *   at which a new queue entered the burst list, then the function appends
++ *   Q to the burst list
++ *
++ * . if, as a consequence of the previous step, the burst size reaches
++ *   the large-burst threshold, then
++ *
++ *     . all the queues in the burst list are marked as belonging to a
++ *       large burst
++ *
++ *     . the burst list is deleted; in fact, the burst list already served
++ *       its purpose (keeping temporarily track of the queues in a burst,
++ *       so as to be able to mark them as belonging to a large burst in the
++ *       previous sub-step), and now is not needed any more
++ *
++ *     . the device enters a large-burst mode
++ *
++ * . if a queue Q that does not belong to the burst is activated while
++ *   the device is in large-burst mode and shortly after the last time
++ *   at which a queue either entered the burst list or was marked as
++ *   belonging to the current large burst, then Q is immediately marked
++ *   as belonging to a large burst.
++ *
++ * . if a queue Q that does not belong to the burst is activated a while
++ *   later, i.e., not shortly after, than the last time at which a queue
++ *   either entered the burst list or was marked as belonging to the
++ *   current large burst, then the current burst is deemed as finished and:
++ *
++ *        . the large-burst mode is reset if set
++ *
++ *        . the burst list is emptied
++ *
++ *        . Q is inserted in the burst list, as Q may be the first queue
++ *          in a possible new burst (then the burst list contains just Q
++ *          after this step).
++ */
++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++			     bool idle_for_long_time)
++{
++	/*
++	 * If bfqq happened to be activated in a burst, but has been idle
++	 * for at least as long as an interactive queue, then we assume
++	 * that, in the overall I/O initiated in the burst, the I/O
++	 * associated to bfqq is finished. So bfqq does not need to be
++	 * treated as a queue belonging to a burst anymore. Accordingly,
++	 * we reset bfqq's in_large_burst flag if set, and remove bfqq
++	 * from the burst list if it's there. We do not decrement instead
++	 * burst_size, because the fact that bfqq does not need to belong
++	 * to the burst list any more does not invalidate the fact that
++	 * bfqq may have been activated during the current burst.
++	 */
++	if (idle_for_long_time) {
++		hlist_del_init(&bfqq->burst_list_node);
++		bfq_clear_bfqq_in_large_burst(bfqq);
++	}
++
++	/*
++	 * If bfqq is already in the burst list or is part of a large
++	 * burst, then there is nothing else to do.
++	 */
++	if (!hlist_unhashed(&bfqq->burst_list_node) ||
++	    bfq_bfqq_in_large_burst(bfqq))
++		return;
++
++	/*
++	 * If bfqq's activation happens late enough, then the current
++	 * burst is finished, and related data structures must be reset.
++	 *
++	 * In this respect, consider the special case where bfqq is the very
++	 * first queue being activated. In this case, last_ins_in_burst is
++	 * not yet significant when we get here. But it is easy to verify
++	 * that, whether or not the following condition is true, bfqq will
++	 * end up being inserted into the burst list. In particular the
++	 * list will happen to contain only bfqq. And this is exactly what
++	 * has to happen, as bfqq may be the first queue in a possible
++	 * burst.
++	 */
++	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
++	    bfqd->bfq_burst_interval)) {
++		bfqd->large_burst = false;
++		bfq_reset_burst_list(bfqd, bfqq);
++		return;
++	}
++
++	/*
++	 * If we get here, then bfqq is being activated shortly after the
++	 * last queue. So, if the current burst is also large, we can mark
++	 * bfqq as belonging to this large burst immediately.
++	 */
++	if (bfqd->large_burst) {
++		bfq_mark_bfqq_in_large_burst(bfqq);
++		return;
++	}
++
++	/*
++	 * If we get here, then a large-burst state has not yet been
++	 * reached, but bfqq is being activated shortly after the last
++	 * queue. Then we add bfqq to the burst.
++	 */
++	bfq_add_to_burst(bfqd, bfqq);
++}
++
++static void bfq_add_request(struct request *rq)
++{
++	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++	struct bfq_entity *entity = &bfqq->entity;
++	struct bfq_data *bfqd = bfqq->bfqd;
++	struct request *next_rq, *prev;
++	unsigned long old_wr_coeff = bfqq->wr_coeff;
++	bool interactive = false;
++
++	bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq));
++	bfqq->queued[rq_is_sync(rq)]++;
++	bfqd->queued++;
++
++	elv_rb_add(&bfqq->sort_list, rq);
++
++	/*
++	 * Check if this request is a better next-serve candidate.
++	 */
++	prev = bfqq->next_rq;
++	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
++	BUG_ON(!next_rq);
++	bfqq->next_rq = next_rq;
++
++	if (!bfq_bfqq_busy(bfqq)) {
++		bool soft_rt, in_burst,
++		     idle_for_long_time = time_is_before_jiffies(
++						bfqq->budget_timeout +
++						bfqd->bfq_wr_min_idle_time);
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq,
++					 rq->cmd_flags);
++#endif
++		if (bfq_bfqq_sync(bfqq)) {
++			bool already_in_burst =
++			   !hlist_unhashed(&bfqq->burst_list_node) ||
++			   bfq_bfqq_in_large_burst(bfqq);
++			bfq_handle_burst(bfqd, bfqq, idle_for_long_time);
++			/*
++			 * If bfqq was not already in the current burst,
++			 * then, at this point, bfqq either has been
++			 * added to the current burst or has caused the
++			 * current burst to terminate. In particular, in
++			 * the second case, bfqq has become the first
++			 * queue in a possible new burst.
++			 * In both cases last_ins_in_burst needs to be
++			 * moved forward.
++			 */
++			if (!already_in_burst)
++				bfqd->last_ins_in_burst = jiffies;
++		}
++
++		in_burst = bfq_bfqq_in_large_burst(bfqq);
++		soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
++			!in_burst &&
++			time_is_before_jiffies(bfqq->soft_rt_next_start);
++		interactive = !in_burst && idle_for_long_time;
++		entity->budget = max_t(unsigned long, bfqq->max_budget,
++				       bfq_serv_to_charge(next_rq, bfqq));
++
++		if (!bfq_bfqq_IO_bound(bfqq)) {
++			if (time_before(jiffies,
++					RQ_BIC(rq)->ttime.last_end_request +
++					bfqd->bfq_slice_idle)) {
++				bfqq->requests_within_timer++;
++				if (bfqq->requests_within_timer >=
++				    bfqd->bfq_requests_within_timer)
++					bfq_mark_bfqq_IO_bound(bfqq);
++			} else
++				bfqq->requests_within_timer = 0;
++		}
++
++		if (!bfqd->low_latency)
++			goto add_bfqq_busy;
++
++		/*
++		 * If the queue:
++		 * - is not being boosted,
++		 * - has been idle for enough time,
++		 * - is not a sync queue or is linked to a bfq_io_cq (it is
++		 *   shared "for its nature" or it is not shared and its
++		 *   requests have not been redirected to a shared queue)
++		 * start a weight-raising period.
++		 */
++		if (old_wr_coeff == 1 && (interactive || soft_rt) &&
++		    (!bfq_bfqq_sync(bfqq) || bfqq->bic)) {
++			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
++			if (interactive)
++				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
++			else
++				bfqq->wr_cur_max_time =
++					bfqd->bfq_wr_rt_max_time;
++			bfq_log_bfqq(bfqd, bfqq,
++				     "wrais starting at %lu, rais_max_time %u",
++				     jiffies,
++				     jiffies_to_msecs(bfqq->wr_cur_max_time));
++		} else if (old_wr_coeff > 1) {
++			if (interactive)
++				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
++			else if (in_burst ||
++				 (bfqq->wr_cur_max_time ==
++				  bfqd->bfq_wr_rt_max_time &&
++				  !soft_rt)) {
++				bfqq->wr_coeff = 1;
++				bfq_log_bfqq(bfqd, bfqq,
++					"wrais ending at %lu, rais_max_time %u",
++					jiffies,
++					jiffies_to_msecs(bfqq->
++						wr_cur_max_time));
++			} else if (time_before(
++					bfqq->last_wr_start_finish +
++					bfqq->wr_cur_max_time,
++					jiffies +
++					bfqd->bfq_wr_rt_max_time) &&
++				   soft_rt) {
++				/*
++				 *
++				 * The remaining weight-raising time is lower
++				 * than bfqd->bfq_wr_rt_max_time, which means
++				 * that the application is enjoying weight
++				 * raising either because deemed soft-rt in
++				 * the near past, or because deemed interactive
++				 * a long ago.
++				 * In both cases, resetting now the current
++				 * remaining weight-raising time for the
++				 * application to the weight-raising duration
++				 * for soft rt applications would not cause any
++				 * latency increase for the application (as the
++				 * new duration would be higher than the
++				 * remaining time).
++				 *
++				 * In addition, the application is now meeting
++				 * the requirements for being deemed soft rt.
++				 * In the end we can correctly and safely
++				 * (re)charge the weight-raising duration for
++				 * the application with the weight-raising
++				 * duration for soft rt applications.
++				 *
++				 * In particular, doing this recharge now, i.e.,
++				 * before the weight-raising period for the
++				 * application finishes, reduces the probability
++				 * of the following negative scenario:
++				 * 1) the weight of a soft rt application is
++				 *    raised at startup (as for any newly
++				 *    created application),
++				 * 2) since the application is not interactive,
++				 *    at a certain time weight-raising is
++				 *    stopped for the application,
++				 * 3) at that time the application happens to
++				 *    still have pending requests, and hence
++				 *    is destined to not have a chance to be
++				 *    deemed soft rt before these requests are
++				 *    completed (see the comments to the
++				 *    function bfq_bfqq_softrt_next_start()
++				 *    for details on soft rt detection),
++				 * 4) these pending requests experience a high
++				 *    latency because the application is not
++				 *    weight-raised while they are pending.
++				 */
++				bfqq->last_wr_start_finish = jiffies;
++				bfqq->wr_cur_max_time =
++					bfqd->bfq_wr_rt_max_time;
++			}
++		}
++		if (old_wr_coeff != bfqq->wr_coeff)
++			entity->prio_changed = 1;
++add_bfqq_busy:
++		bfqq->last_idle_bklogged = jiffies;
++		bfqq->service_from_backlogged = 0;
++		bfq_clear_bfqq_softrt_update(bfqq);
++		bfq_add_bfqq_busy(bfqd, bfqq);
++	} else {
++		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
++		    time_is_before_jiffies(
++				bfqq->last_wr_start_finish +
++				bfqd->bfq_wr_min_inter_arr_async)) {
++			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
++			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
++
++			bfqd->wr_busy_queues++;
++			entity->prio_changed = 1;
++			bfq_log_bfqq(bfqd, bfqq,
++			    "non-idle wrais starting at %lu, rais_max_time %u",
++			    jiffies,
++			    jiffies_to_msecs(bfqq->wr_cur_max_time));
++		}
++		if (prev != bfqq->next_rq)
++			bfq_updated_next_req(bfqd, bfqq);
++	}
++
++	if (bfqd->low_latency &&
++		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
++		bfqq->last_wr_start_finish = jiffies;
++}
++
++static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
++					  struct bio *bio)
++{
++	struct task_struct *tsk = current;
++	struct bfq_io_cq *bic;
++	struct bfq_queue *bfqq;
++
++	bic = bfq_bic_lookup(bfqd, tsk->io_context);
++	if (!bic)
++		return NULL;
++
++	bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio));
++	if (bfqq)
++		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
++
++	return NULL;
++}
++
++static void bfq_activate_request(struct request_queue *q, struct request *rq)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++
++	bfqd->rq_in_driver++;
++	bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
++	bfq_log(bfqd, "activate_request: new bfqd->last_position %llu",
++		(long long unsigned)bfqd->last_position);
++}
++
++static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++
++	BUG_ON(bfqd->rq_in_driver == 0);
++	bfqd->rq_in_driver--;
++}
++
++static void bfq_remove_request(struct request *rq)
++{
++	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++	struct bfq_data *bfqd = bfqq->bfqd;
++	const int sync = rq_is_sync(rq);
++
++	if (bfqq->next_rq == rq) {
++		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
++		bfq_updated_next_req(bfqd, bfqq);
++	}
++
++	if (rq->queuelist.prev != &rq->queuelist)
++		list_del_init(&rq->queuelist);
++	BUG_ON(bfqq->queued[sync] == 0);
++	bfqq->queued[sync]--;
++	bfqd->queued--;
++	elv_rb_del(&bfqq->sort_list, rq);
++
++	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
++		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue)
++			bfq_del_bfqq_busy(bfqd, bfqq, 1);
++		/*
++		 * Remove queue from request-position tree as it is empty.
++		 */
++		if (bfqq->pos_root) {
++			rb_erase(&bfqq->pos_node, bfqq->pos_root);
++			bfqq->pos_root = NULL;
++		}
++	}
++
++	if (rq->cmd_flags & REQ_META) {
++		BUG_ON(bfqq->meta_pending == 0);
++		bfqq->meta_pending--;
++	}
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
++#endif
++}
++
++static int bfq_merge(struct request_queue *q, struct request **req,
++		     struct bio *bio)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct request *__rq;
++
++	__rq = bfq_find_rq_fmerge(bfqd, bio);
++	if (__rq && elv_rq_merge_ok(__rq, bio)) {
++		*req = __rq;
++		return ELEVATOR_FRONT_MERGE;
++	}
++
++	return ELEVATOR_NO_MERGE;
++}
++
++static void bfq_merged_request(struct request_queue *q, struct request *req,
++			       int type)
++{
++	if (type == ELEVATOR_FRONT_MERGE &&
++	    rb_prev(&req->rb_node) &&
++	    blk_rq_pos(req) <
++	    blk_rq_pos(container_of(rb_prev(&req->rb_node),
++				    struct request, rb_node))) {
++		struct bfq_queue *bfqq = RQ_BFQQ(req);
++		struct bfq_data *bfqd = bfqq->bfqd;
++		struct request *prev, *next_rq;
++
++		/* Reposition request in its sort_list */
++		elv_rb_del(&bfqq->sort_list, req);
++		elv_rb_add(&bfqq->sort_list, req);
++		/* Choose next request to be served for bfqq */
++		prev = bfqq->next_rq;
++		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
++					 bfqd->last_position);
++		BUG_ON(!next_rq);
++		bfqq->next_rq = next_rq;
++	}
++}
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++static void bfq_bio_merged(struct request_queue *q, struct request *req,
++			   struct bio *bio)
++{
++	bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_rw);
++}
++#endif
++
++static void bfq_merged_requests(struct request_queue *q, struct request *rq,
++				struct request *next)
++{
++	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
++
++	/*
++	 * If next and rq belong to the same bfq_queue and next is older
++	 * than rq, then reposition rq in the fifo (by substituting next
++	 * with rq). Otherwise, if next and rq belong to different
++	 * bfq_queues, never reposition rq: in fact, we would have to
++	 * reposition it with respect to next's position in its own fifo,
++	 * which would most certainly be too expensive with respect to
++	 * the benefits.
++	 */
++	if (bfqq == next_bfqq &&
++	    !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
++	    time_before(next->fifo_time, rq->fifo_time)) {
++		list_del_init(&rq->queuelist);
++		list_replace_init(&next->queuelist, &rq->queuelist);
++		rq->fifo_time = next->fifo_time;
++	}
++
++	if (bfqq->next_rq == next)
++		bfqq->next_rq = rq;
++
++	bfq_remove_request(next);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
++#endif
++}
++
++/* Must be called with bfqq != NULL */
++static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
++{
++	BUG_ON(!bfqq);
++	if (bfq_bfqq_busy(bfqq))
++		bfqq->bfqd->wr_busy_queues--;
++	bfqq->wr_coeff = 1;
++	bfqq->wr_cur_max_time = 0;
++	/* Trigger a weight change on the next activation of the queue */
++	bfqq->entity.prio_changed = 1;
++}
++
++static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
++				    struct bfq_group *bfqg)
++{
++	int i, j;
++
++	for (i = 0; i < 2; i++)
++		for (j = 0; j < IOPRIO_BE_NR; j++)
++			if (bfqg->async_bfqq[i][j])
++				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
++	if (bfqg->async_idle_bfqq)
++		bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
++}
++
++static void bfq_end_wr(struct bfq_data *bfqd)
++{
++	struct bfq_queue *bfqq;
++
++	spin_lock_irq(bfqd->queue->queue_lock);
++
++	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
++		bfq_bfqq_end_wr(bfqq);
++	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
++		bfq_bfqq_end_wr(bfqq);
++	bfq_end_wr_async(bfqd);
++
++	spin_unlock_irq(bfqd->queue->queue_lock);
++}
++
++static int bfq_allow_merge(struct request_queue *q, struct request *rq,
++			   struct bio *bio)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct bfq_io_cq *bic;
++
++	/*
++	 * Disallow merge of a sync bio into an async request.
++	 */
++	if (bfq_bio_sync(bio) && !rq_is_sync(rq))
++		return 0;
++
++	/*
++	 * Lookup the bfqq that this bio will be queued with. Allow
++	 * merge only if rq is queued there.
++	 * Queue lock is held here.
++	 */
++	bic = bfq_bic_lookup(bfqd, current->io_context);
++	if (!bic)
++		return 0;
++
++	return bic_to_bfqq(bic, bfq_bio_sync(bio)) == RQ_BFQQ(rq);
++}
++
++static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
++				       struct bfq_queue *bfqq)
++{
++	if (bfqq) {
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
++#endif
++		bfq_mark_bfqq_must_alloc(bfqq);
++		bfq_mark_bfqq_budget_new(bfqq);
++		bfq_clear_bfqq_fifo_expire(bfqq);
++
++		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
++
++		bfq_log_bfqq(bfqd, bfqq,
++			     "set_in_service_queue, cur-budget = %d",
++			     bfqq->entity.budget);
++	}
++
++	bfqd->in_service_queue = bfqq;
++}
++
++/*
++ * Get and set a new queue for service.
++ */
++static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
++{
++	struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
++
++	__bfq_set_in_service_queue(bfqd, bfqq);
++	return bfqq;
++}
++
++/*
++ * If enough samples have been computed, return the current max budget
++ * stored in bfqd, which is dynamically updated according to the
++ * estimated disk peak rate; otherwise return the default max budget
++ */
++static int bfq_max_budget(struct bfq_data *bfqd)
++{
++	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
++		return bfq_default_max_budget;
++	else
++		return bfqd->bfq_max_budget;
++}
++
++/*
++ * Return min budget, which is a fraction of the current or default
++ * max budget (trying with 1/32)
++ */
++static int bfq_min_budget(struct bfq_data *bfqd)
++{
++	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
++		return bfq_default_max_budget / 32;
++	else
++		return bfqd->bfq_max_budget / 32;
++}
++
++static void bfq_arm_slice_timer(struct bfq_data *bfqd)
++{
++	struct bfq_queue *bfqq = bfqd->in_service_queue;
++	struct bfq_io_cq *bic;
++	unsigned long sl;
++
++	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
++
++	/* Processes have exited, don't wait. */
++	bic = bfqd->in_service_bic;
++	if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
++		return;
++
++	bfq_mark_bfqq_wait_request(bfqq);
++
++	/*
++	 * We don't want to idle for seeks, but we do want to allow
++	 * fair distribution of slice time for a process doing back-to-back
++	 * seeks. So allow a little bit of time for him to submit a new rq.
++	 *
++	 * To prevent processes with (partly) seeky workloads from
++	 * being too ill-treated, grant them a small fraction of the
++	 * assigned budget before reducing the waiting time to
++	 * BFQ_MIN_TT. This happened to help reduce latency.
++	 */
++	sl = bfqd->bfq_slice_idle;
++	/*
++	 * Unless the queue is being weight-raised or the scenario is
++	 * asymmetric, grant only minimum idle time if the queue either
++	 * has been seeky for long enough or has already proved to be
++	 * constantly seeky.
++	 */
++	if (bfq_sample_valid(bfqq->seek_samples) &&
++	    ((BFQQ_SEEKY(bfqq) && bfqq->entity.service >
++				  bfq_max_budget(bfqq->bfqd) / 8) ||
++	      bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1 &&
++	    bfq_symmetric_scenario(bfqd))
++		sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT));
++	else if (bfqq->wr_coeff > 1)
++		sl = sl * 3;
++	bfqd->last_idling_start = ktime_get();
++	mod_timer(&bfqd->idle_slice_timer, jiffies + sl);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
++#endif
++	bfq_log(bfqd, "arm idle: %u/%u ms",
++		jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle));
++}
++
++/*
++ * Set the maximum time for the in-service queue to consume its
++ * budget. This prevents seeky processes from lowering the disk
++ * throughput (always guaranteed with a time slice scheme as in CFQ).
++ */
++static void bfq_set_budget_timeout(struct bfq_data *bfqd)
++{
++	struct bfq_queue *bfqq = bfqd->in_service_queue;
++	unsigned int timeout_coeff;
++	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
++		timeout_coeff = 1;
++	else
++		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
++
++	bfqd->last_budget_start = ktime_get();
++
++	bfq_clear_bfqq_budget_new(bfqq);
++	bfqq->budget_timeout = jiffies +
++		bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff;
++
++	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
++		jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] *
++		timeout_coeff));
++}
++
++/*
++ * Move request from internal lists to the request queue dispatch list.
++ */
++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++
++	/*
++	 * For consistency, the next instruction should have been executed
++	 * after removing the request from the queue and dispatching it.
++	 * We execute instead this instruction before bfq_remove_request()
++	 * (and hence introduce a temporary inconsistency), for efficiency.
++	 * In fact, in a forced_dispatch, this prevents two counters related
++	 * to bfqq->dispatched to risk to be uselessly decremented if bfqq
++	 * is not in service, and then to be incremented again after
++	 * incrementing bfqq->dispatched.
++	 */
++	bfqq->dispatched++;
++	bfq_remove_request(rq);
++	elv_dispatch_sort(q, rq);
++
++	if (bfq_bfqq_sync(bfqq))
++		bfqd->sync_flight++;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_update_dispatch(bfqq_group(bfqq), blk_rq_bytes(rq),
++				   rq->cmd_flags);
++#endif
++}
++
++/*
++ * Return expired entry, or NULL to just start from scratch in rbtree.
++ */
++static struct request *bfq_check_fifo(struct bfq_queue *bfqq)
++{
++	struct request *rq = NULL;
++
++	if (bfq_bfqq_fifo_expire(bfqq))
++		return NULL;
++
++	bfq_mark_bfqq_fifo_expire(bfqq);
++
++	if (list_empty(&bfqq->fifo))
++		return NULL;
++
++	rq = rq_entry_fifo(bfqq->fifo.next);
++
++	if (time_before(jiffies, rq->fifo_time))
++		return NULL;
++
++	return rq;
++}
++
++static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++	return entity->budget - entity->service;
++}
++
++static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	BUG_ON(bfqq != bfqd->in_service_queue);
++
++	__bfq_bfqd_reset_in_service(bfqd);
++
++	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
++		/*
++		 * Overloading budget_timeout field to store the time
++		 * at which the queue remains with no backlog; used by
++		 * the weight-raising mechanism.
++		 */
++		bfqq->budget_timeout = jiffies;
++		bfq_del_bfqq_busy(bfqd, bfqq, 1);
++	} else
++		bfq_activate_bfqq(bfqd, bfqq);
++}
++
++/**
++ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
++ * @bfqd: device data.
++ * @bfqq: queue to update.
++ * @reason: reason for expiration.
++ *
++ * Handle the feedback on @bfqq budget at queue expiration.
++ * See the body for detailed comments.
++ */
++static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
++				     struct bfq_queue *bfqq,
++				     enum bfqq_expiration reason)
++{
++	struct request *next_rq;
++	int budget, min_budget;
++
++	budget = bfqq->max_budget;
++	min_budget = bfq_min_budget(bfqd);
++
++	BUG_ON(bfqq != bfqd->in_service_queue);
++
++	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
++		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
++	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
++		budget, bfq_min_budget(bfqd));
++	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
++		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
++
++	if (bfq_bfqq_sync(bfqq)) {
++		switch (reason) {
++		/*
++		 * Caveat: in all the following cases we trade latency
++		 * for throughput.
++		 */
++		case BFQ_BFQQ_TOO_IDLE:
++			/*
++			 * This is the only case where we may reduce
++			 * the budget: if there is no request of the
++			 * process still waiting for completion, then
++			 * we assume (tentatively) that the timer has
++			 * expired because the batch of requests of
++			 * the process could have been served with a
++			 * smaller budget.  Hence, betting that
++			 * process will behave in the same way when it
++			 * becomes backlogged again, we reduce its
++			 * next budget.  As long as we guess right,
++			 * this budget cut reduces the latency
++			 * experienced by the process.
++			 *
++			 * However, if there are still outstanding
++			 * requests, then the process may have not yet
++			 * issued its next request just because it is
++			 * still waiting for the completion of some of
++			 * the still outstanding ones.  So in this
++			 * subcase we do not reduce its budget, on the
++			 * contrary we increase it to possibly boost
++			 * the throughput, as discussed in the
++			 * comments to the BUDGET_TIMEOUT case.
++			 */
++			if (bfqq->dispatched > 0) /* still outstanding reqs */
++				budget = min(budget * 2, bfqd->bfq_max_budget);
++			else {
++				if (budget > 5 * min_budget)
++					budget -= 4 * min_budget;
++				else
++					budget = min_budget;
++			}
++			break;
++		case BFQ_BFQQ_BUDGET_TIMEOUT:
++			/*
++			 * We double the budget here because: 1) it
++			 * gives the chance to boost the throughput if
++			 * this is not a seeky process (which may have
++			 * bumped into this timeout because of, e.g.,
++			 * ZBR), 2) together with charge_full_budget
++			 * it helps give seeky processes higher
++			 * timestamps, and hence be served less
++			 * frequently.
++			 */
++			budget = min(budget * 2, bfqd->bfq_max_budget);
++			break;
++		case BFQ_BFQQ_BUDGET_EXHAUSTED:
++			/*
++			 * The process still has backlog, and did not
++			 * let either the budget timeout or the disk
++			 * idling timeout expire. Hence it is not
++			 * seeky, has a short thinktime and may be
++			 * happy with a higher budget too. So
++			 * definitely increase the budget of this good
++			 * candidate to boost the disk throughput.
++			 */
++			budget = min(budget * 4, bfqd->bfq_max_budget);
++			break;
++		case BFQ_BFQQ_NO_MORE_REQUESTS:
++		       /*
++			* Leave the budget unchanged.
++			*/
++		default:
++			return;
++		}
++	} else
++		/*
++		 * Async queues get always the maximum possible budget
++		 * (their ability to dispatch is limited by
++		 * @bfqd->bfq_max_budget_async_rq).
++		 */
++		budget = bfqd->bfq_max_budget;
++
++	bfqq->max_budget = budget;
++
++	if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
++	    !bfqd->bfq_user_max_budget)
++		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
++
++	/*
++	 * Make sure that we have enough budget for the next request.
++	 * Since the finish time of the bfqq must be kept in sync with
++	 * the budget, be sure to call __bfq_bfqq_expire() after the
++	 * update.
++	 */
++	next_rq = bfqq->next_rq;
++	if (next_rq)
++		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
++					    bfq_serv_to_charge(next_rq, bfqq));
++	else
++		bfqq->entity.budget = bfqq->max_budget;
++
++	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
++			next_rq ? blk_rq_sectors(next_rq) : 0,
++			bfqq->entity.budget);
++}
++
++static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout)
++{
++	unsigned long max_budget;
++
++	/*
++	 * The max_budget calculated when autotuning is equal to the
++	 * amount of sectors transfered in timeout_sync at the
++	 * estimated peak rate.
++	 */
++	max_budget = (unsigned long)(peak_rate * 1000 *
++				     timeout >> BFQ_RATE_SHIFT);
++
++	return max_budget;
++}
++
++/*
++ * In addition to updating the peak rate, checks whether the process
++ * is "slow", and returns 1 if so. This slow flag is used, in addition
++ * to the budget timeout, to reduce the amount of service provided to
++ * seeky processes, and hence reduce their chances to lower the
++ * throughput. See the code for more details.
++ */
++static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++				 bool compensate, enum bfqq_expiration reason)
++{
++	u64 bw, usecs, expected, timeout;
++	ktime_t delta;
++	int update = 0;
++
++	if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq))
++		return false;
++
++	if (compensate)
++		delta = bfqd->last_idling_start;
++	else
++		delta = ktime_get();
++	delta = ktime_sub(delta, bfqd->last_budget_start);
++	usecs = ktime_to_us(delta);
++
++	/* Don't trust short/unrealistic values. */
++	if (usecs < 100 || usecs >= LONG_MAX)
++		return false;
++
++	/*
++	 * Calculate the bandwidth for the last slice.  We use a 64 bit
++	 * value to store the peak rate, in sectors per usec in fixed
++	 * point math.  We do so to have enough precision in the estimate
++	 * and to avoid overflows.
++	 */
++	bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT;
++	do_div(bw, (unsigned long)usecs);
++
++	timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
++
++	/*
++	 * Use only long (> 20ms) intervals to filter out spikes for
++	 * the peak rate estimation.
++	 */
++	if (usecs > 20000) {
++		if (bw > bfqd->peak_rate ||
++		   (!BFQQ_SEEKY(bfqq) &&
++		    reason == BFQ_BFQQ_BUDGET_TIMEOUT)) {
++			bfq_log(bfqd, "measured bw =%llu", bw);
++			/*
++			 * To smooth oscillations use a low-pass filter with
++			 * alpha=7/8, i.e.,
++			 * new_rate = (7/8) * old_rate + (1/8) * bw
++			 */
++			do_div(bw, 8);
++			if (bw == 0)
++				return 0;
++			bfqd->peak_rate *= 7;
++			do_div(bfqd->peak_rate, 8);
++			bfqd->peak_rate += bw;
++			update = 1;
++			bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate);
++		}
++
++		update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1;
++
++		if (bfqd->peak_rate_samples < BFQ_PEAK_RATE_SAMPLES)
++			bfqd->peak_rate_samples++;
++
++		if (bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES &&
++		    update) {
++			int dev_type = blk_queue_nonrot(bfqd->queue);
++			if (bfqd->bfq_user_max_budget == 0) {
++				bfqd->bfq_max_budget =
++					bfq_calc_max_budget(bfqd->peak_rate,
++							    timeout);
++				bfq_log(bfqd, "new max_budget=%d",
++					bfqd->bfq_max_budget);
++			}
++			if (bfqd->device_speed == BFQ_BFQD_FAST &&
++			    bfqd->peak_rate < device_speed_thresh[dev_type]) {
++				bfqd->device_speed = BFQ_BFQD_SLOW;
++				bfqd->RT_prod = R_slow[dev_type] *
++						T_slow[dev_type];
++			} else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
++			    bfqd->peak_rate > device_speed_thresh[dev_type]) {
++				bfqd->device_speed = BFQ_BFQD_FAST;
++				bfqd->RT_prod = R_fast[dev_type] *
++						T_fast[dev_type];
++			}
++		}
++	}
++
++	/*
++	 * If the process has been served for a too short time
++	 * interval to let its possible sequential accesses prevail on
++	 * the initial seek time needed to move the disk head on the
++	 * first sector it requested, then give the process a chance
++	 * and for the moment return false.
++	 */
++	if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8)
++		return false;
++
++	/*
++	 * A process is considered ``slow'' (i.e., seeky, so that we
++	 * cannot treat it fairly in the service domain, as it would
++	 * slow down too much the other processes) if, when a slice
++	 * ends for whatever reason, it has received service at a
++	 * rate that would not be high enough to complete the budget
++	 * before the budget timeout expiration.
++	 */
++	expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT;
++
++	/*
++	 * Caveat: processes doing IO in the slower disk zones will
++	 * tend to be slow(er) even if not seeky. And the estimated
++	 * peak rate will actually be an average over the disk
++	 * surface. Hence, to not be too harsh with unlucky processes,
++	 * we keep a budget/3 margin of safety before declaring a
++	 * process slow.
++	 */
++	return expected > (4 * bfqq->entity.budget) / 3;
++}
++
++/*
++ * To be deemed as soft real-time, an application must meet two
++ * requirements. First, the application must not require an average
++ * bandwidth higher than the approximate bandwidth required to playback or
++ * record a compressed high-definition video.
++ * The next function is invoked on the completion of the last request of a
++ * batch, to compute the next-start time instant, soft_rt_next_start, such
++ * that, if the next request of the application does not arrive before
++ * soft_rt_next_start, then the above requirement on the bandwidth is met.
++ *
++ * The second requirement is that the request pattern of the application is
++ * isochronous, i.e., that, after issuing a request or a batch of requests,
++ * the application stops issuing new requests until all its pending requests
++ * have been completed. After that, the application may issue a new batch,
++ * and so on.
++ * For this reason the next function is invoked to compute
++ * soft_rt_next_start only for applications that meet this requirement,
++ * whereas soft_rt_next_start is set to infinity for applications that do
++ * not.
++ *
++ * Unfortunately, even a greedy application may happen to behave in an
++ * isochronous way if the CPU load is high. In fact, the application may
++ * stop issuing requests while the CPUs are busy serving other processes,
++ * then restart, then stop again for a while, and so on. In addition, if
++ * the disk achieves a low enough throughput with the request pattern
++ * issued by the application (e.g., because the request pattern is random
++ * and/or the device is slow), then the application may meet the above
++ * bandwidth requirement too. To prevent such a greedy application to be
++ * deemed as soft real-time, a further rule is used in the computation of
++ * soft_rt_next_start: soft_rt_next_start must be higher than the current
++ * time plus the maximum time for which the arrival of a request is waited
++ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
++ * This filters out greedy applications, as the latter issue instead their
++ * next request as soon as possible after the last one has been completed
++ * (in contrast, when a batch of requests is completed, a soft real-time
++ * application spends some time processing data).
++ *
++ * Unfortunately, the last filter may easily generate false positives if
++ * only bfqd->bfq_slice_idle is used as a reference time interval and one
++ * or both the following cases occur:
++ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
++ *    than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
++ *    HZ=100.
++ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
++ *    for a while, then suddenly 'jump' by several units to recover the lost
++ *    increments. This seems to happen, e.g., inside virtual machines.
++ * To address this issue, we do not use as a reference time interval just
++ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
++ * particular we add the minimum number of jiffies for which the filter
++ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
++ * machines.
++ */
++static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
++						struct bfq_queue *bfqq)
++{
++	return max(bfqq->last_idle_bklogged +
++		   HZ * bfqq->service_from_backlogged /
++		   bfqd->bfq_wr_max_softrt_rate,
++		   jiffies + bfqq->bfqd->bfq_slice_idle + 4);
++}
++
++/*
++ * Return the largest-possible time instant such that, for as long as possible,
++ * the current time will be lower than this time instant according to the macro
++ * time_is_before_jiffies().
++ */
++static unsigned long bfq_infinity_from_now(unsigned long now)
++{
++	return now + ULONG_MAX / 2;
++}
++
++/**
++ * bfq_bfqq_expire - expire a queue.
++ * @bfqd: device owning the queue.
++ * @bfqq: the queue to expire.
++ * @compensate: if true, compensate for the time spent idling.
++ * @reason: the reason causing the expiration.
++ *
++ *
++ * If the process associated to the queue is slow (i.e., seeky), or in
++ * case of budget timeout, or, finally, if it is async, we
++ * artificially charge it an entire budget (independently of the
++ * actual service it received). As a consequence, the queue will get
++ * higher timestamps than the correct ones upon reactivation, and
++ * hence it will be rescheduled as if it had received more service
++ * than what it actually received. In the end, this class of processes
++ * will receive less service in proportion to how slowly they consume
++ * their budgets (and hence how seriously they tend to lower the
++ * throughput).
++ *
++ * In contrast, when a queue expires because it has been idling for
++ * too much or because it exhausted its budget, we do not touch the
++ * amount of service it has received. Hence when the queue will be
++ * reactivated and its timestamps updated, the latter will be in sync
++ * with the actual service received by the queue until expiration.
++ *
++ * Charging a full budget to the first type of queues and the exact
++ * service to the others has the effect of using the WF2Q+ policy to
++ * schedule the former on a timeslice basis, without violating the
++ * service domain guarantees of the latter.
++ */
++static void bfq_bfqq_expire(struct bfq_data *bfqd,
++			    struct bfq_queue *bfqq,
++			    bool compensate,
++			    enum bfqq_expiration reason)
++{
++	bool slow;
++	BUG_ON(bfqq != bfqd->in_service_queue);
++
++	/*
++	 * Update disk peak rate for autotuning and check whether the
++	 * process is slow (see bfq_update_peak_rate).
++	 */
++	slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason);
++
++	/*
++	 * As above explained, 'punish' slow (i.e., seeky), timed-out
++	 * and async queues, to favor sequential sync workloads.
++	 *
++	 * Processes doing I/O in the slower disk zones will tend to be
++	 * slow(er) even if not seeky. Hence, since the estimated peak
++	 * rate is actually an average over the disk surface, these
++	 * processes may timeout just for bad luck. To avoid punishing
++	 * them we do not charge a full budget to a process that
++	 * succeeded in consuming at least 2/3 of its budget.
++	 */
++	if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
++		     bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3))
++		bfq_bfqq_charge_full_budget(bfqq);
++
++	bfqq->service_from_backlogged += bfqq->entity.service;
++
++	if (BFQQ_SEEKY(bfqq) && reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
++	    !bfq_bfqq_constantly_seeky(bfqq)) {
++		bfq_mark_bfqq_constantly_seeky(bfqq);
++		if (!blk_queue_nonrot(bfqd->queue))
++			bfqd->const_seeky_busy_in_flight_queues++;
++	}
++
++	if (reason == BFQ_BFQQ_TOO_IDLE &&
++	    bfqq->entity.service <= 2 * bfqq->entity.budget / 10 )
++		bfq_clear_bfqq_IO_bound(bfqq);
++
++	if (bfqd->low_latency && bfqq->wr_coeff == 1)
++		bfqq->last_wr_start_finish = jiffies;
++
++	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
++	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
++		/*
++		 * If we get here, and there are no outstanding requests,
++		 * then the request pattern is isochronous (see the comments
++		 * to the function bfq_bfqq_softrt_next_start()). Hence we
++		 * can compute soft_rt_next_start. If, instead, the queue
++		 * still has outstanding requests, then we have to wait
++		 * for the completion of all the outstanding requests to
++		 * discover whether the request pattern is actually
++		 * isochronous.
++		 */
++		if (bfqq->dispatched == 0)
++			bfqq->soft_rt_next_start =
++				bfq_bfqq_softrt_next_start(bfqd, bfqq);
++		else {
++			/*
++			 * The application is still waiting for the
++			 * completion of one or more requests:
++			 * prevent it from possibly being incorrectly
++			 * deemed as soft real-time by setting its
++			 * soft_rt_next_start to infinity. In fact,
++			 * without this assignment, the application
++			 * would be incorrectly deemed as soft
++			 * real-time if:
++			 * 1) it issued a new request before the
++			 *    completion of all its in-flight
++			 *    requests, and
++			 * 2) at that time, its soft_rt_next_start
++			 *    happened to be in the past.
++			 */
++			bfqq->soft_rt_next_start =
++				bfq_infinity_from_now(jiffies);
++			/*
++			 * Schedule an update of soft_rt_next_start to when
++			 * the task may be discovered to be isochronous.
++			 */
++			bfq_mark_bfqq_softrt_update(bfqq);
++		}
++	}
++
++	bfq_log_bfqq(bfqd, bfqq,
++		"expire (%d, slow %d, num_disp %d, idle_win %d)", reason,
++		slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq));
++
++	/*
++	 * Increase, decrease or leave budget unchanged according to
++	 * reason.
++	 */
++	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
++	__bfq_bfqq_expire(bfqd, bfqq);
++}
++
++/*
++ * Budget timeout is not implemented through a dedicated timer, but
++ * just checked on request arrivals and completions, as well as on
++ * idle timer expirations.
++ */
++static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
++{
++	if (bfq_bfqq_budget_new(bfqq) ||
++	    time_before(jiffies, bfqq->budget_timeout))
++		return false;
++	return true;
++}
++
++/*
++ * If we expire a queue that is waiting for the arrival of a new
++ * request, we may prevent the fictitious timestamp back-shifting that
++ * allows the guarantees of the queue to be preserved (see [1] for
++ * this tricky aspect). Hence we return true only if this condition
++ * does not hold, or if the queue is slow enough to deserve only to be
++ * kicked off for preserving a high throughput.
++*/
++static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
++{
++	bfq_log_bfqq(bfqq->bfqd, bfqq,
++		"may_budget_timeout: wait_request %d left %d timeout %d",
++		bfq_bfqq_wait_request(bfqq),
++			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
++		bfq_bfqq_budget_timeout(bfqq));
++
++	return (!bfq_bfqq_wait_request(bfqq) ||
++		bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3)
++		&&
++		bfq_bfqq_budget_timeout(bfqq);
++}
++
++/*
++ * For a queue that becomes empty, device idling is allowed only if
++ * this function returns true for that queue. As a consequence, since
++ * device idling plays a critical role for both throughput boosting
++ * and service guarantees, the return value of this function plays a
++ * critical role as well.
++ *
++ * In a nutshell, this function returns true only if idling is
++ * beneficial for throughput or, even if detrimental for throughput,
++ * idling is however necessary to preserve service guarantees (low
++ * latency, desired throughput distribution, ...). In particular, on
++ * NCQ-capable devices, this function tries to return false, so as to
++ * help keep the drives' internal queues full, whenever this helps the
++ * device boost the throughput without causing any service-guarantee
++ * issue.
++ *
++ * In more detail, the return value of this function is obtained by,
++ * first, computing a number of boolean variables that take into
++ * account throughput and service-guarantee issues, and, then,
++ * combining these variables in a logical expression. Most of the
++ * issues taken into account are not trivial. We discuss these issues
++ * while introducing the variables.
++ */
++static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
++{
++	struct bfq_data *bfqd = bfqq->bfqd;
++	bool idling_boosts_thr, idling_boosts_thr_without_issues,
++		all_queues_seeky, on_hdd_and_not_all_queues_seeky,
++		idling_needed_for_service_guarantees,
++		asymmetric_scenario;
++
++	/*
++	 * The next variable takes into account the cases where idling
++	 * boosts the throughput.
++	 *
++	 * The value of the variable is computed considering, first, that
++	 * idling is virtually always beneficial for the throughput if:
++	 * (a) the device is not NCQ-capable, or
++	 * (b) regardless of the presence of NCQ, the device is rotational
++	 *     and the request pattern for bfqq is I/O-bound and sequential.
++	 *
++	 * Secondly, and in contrast to the above item (b), idling an
++	 * NCQ-capable flash-based device would not boost the
++	 * throughput even with sequential I/O; rather it would lower
++	 * the throughput in proportion to how fast the device
++	 * is. Accordingly, the next variable is true if any of the
++	 * above conditions (a) and (b) is true, and, in particular,
++	 * happens to be false if bfqd is an NCQ-capable flash-based
++	 * device.
++	 */
++	idling_boosts_thr = !bfqd->hw_tag ||
++		(!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
++		 bfq_bfqq_idle_window(bfqq)) ;
++
++	/*
++	 * The value of the next variable,
++	 * idling_boosts_thr_without_issues, is equal to that of
++	 * idling_boosts_thr, unless a special case holds. In this
++	 * special case, described below, idling may cause problems to
++	 * weight-raised queues.
++	 *
++	 * When the request pool is saturated (e.g., in the presence
++	 * of write hogs), if the processes associated with
++	 * non-weight-raised queues ask for requests at a lower rate,
++	 * then processes associated with weight-raised queues have a
++	 * higher probability to get a request from the pool
++	 * immediately (or at least soon) when they need one. Thus
++	 * they have a higher probability to actually get a fraction
++	 * of the device throughput proportional to their high
++	 * weight. This is especially true with NCQ-capable drives,
++	 * which enqueue several requests in advance, and further
++	 * reorder internally-queued requests.
++	 *
++	 * For this reason, we force to false the value of
++	 * idling_boosts_thr_without_issues if there are weight-raised
++	 * busy queues. In this case, and if bfqq is not weight-raised,
++	 * this guarantees that the device is not idled for bfqq (if,
++	 * instead, bfqq is weight-raised, then idling will be
++	 * guaranteed by another variable, see below). Combined with
++	 * the timestamping rules of BFQ (see [1] for details), this
++	 * behavior causes bfqq, and hence any sync non-weight-raised
++	 * queue, to get a lower number of requests served, and thus
++	 * to ask for a lower number of requests from the request
++	 * pool, before the busy weight-raised queues get served
++	 * again. This often mitigates starvation problems in the
++	 * presence of heavy write workloads and NCQ, thereby
++	 * guaranteeing a higher application and system responsiveness
++	 * in these hostile scenarios.
++	 */
++	idling_boosts_thr_without_issues = idling_boosts_thr &&
++		bfqd->wr_busy_queues == 0;
++
++	/*
++	 * There are then two cases where idling must be performed not
++	 * for throughput concerns, but to preserve service
++	 * guarantees. In the description of these cases, we say, for
++	 * short, that a queue is sequential/random if the process
++	 * associated to the queue issues sequential/random requests
++	 * (in the second case the queue may be tagged as seeky or
++	 * even constantly_seeky).
++	 *
++	 * To introduce the first case, we note that, since
++	 * bfq_bfqq_idle_window(bfqq) is false if the device is
++	 * NCQ-capable and bfqq is random (see
++	 * bfq_update_idle_window()), then, from the above two
++	 * assignments it follows that
++	 * idling_boosts_thr_without_issues is false if the device is
++	 * NCQ-capable and bfqq is random. Therefore, for this case,
++	 * device idling would never be allowed if we used just
++	 * idling_boosts_thr_without_issues to decide whether to allow
++	 * it. And, beneficially, this would imply that throughput
++	 * would always be boosted also with random I/O on NCQ-capable
++	 * HDDs.
++	 *
++	 * But we must be careful on this point, to avoid an unfair
++	 * treatment for bfqq. In fact, because of the same above
++	 * assignments, idling_boosts_thr_without_issues is, on the
++	 * other hand, true if 1) the device is an HDD and bfqq is
++	 * sequential, and 2) there are no busy weight-raised
++	 * queues. As a consequence, if we used just
++	 * idling_boosts_thr_without_issues to decide whether to idle
++	 * the device, then with an HDD we might easily bump into a
++	 * scenario where queues that are sequential and I/O-bound
++	 * would enjoy idling, whereas random queues would not. The
++	 * latter might then get a low share of the device throughput,
++	 * simply because the former would get many requests served
++	 * after being set as in service, while the latter would not.
++	 *
++	 * To address this issue, we start by setting to true a
++	 * sentinel variable, on_hdd_and_not_all_queues_seeky, if the
++	 * device is rotational and not all queues with pending or
++	 * in-flight requests are constantly seeky (i.e., there are
++	 * active sequential queues, and bfqq might then be mistreated
++	 * if it does not enjoy idling because it is random).
++	 */
++	all_queues_seeky = bfq_bfqq_constantly_seeky(bfqq) &&
++			   bfqd->busy_in_flight_queues ==
++			   bfqd->const_seeky_busy_in_flight_queues;
++
++	on_hdd_and_not_all_queues_seeky =
++		!blk_queue_nonrot(bfqd->queue) && !all_queues_seeky;
++
++	/*
++	 * To introduce the second case where idling needs to be
++	 * performed to preserve service guarantees, we can note that
++	 * allowing the drive to enqueue more than one request at a
++	 * time, and hence delegating de facto final scheduling
++	 * decisions to the drive's internal scheduler, causes loss of
++	 * control on the actual request service order. In particular,
++	 * the critical situation is when requests from different
++	 * processes happens to be present, at the same time, in the
++	 * internal queue(s) of the drive. In such a situation, the
++	 * drive, by deciding the service order of the
++	 * internally-queued requests, does determine also the actual
++	 * throughput distribution among these processes. But the
++	 * drive typically has no notion or concern about per-process
++	 * throughput distribution, and makes its decisions only on a
++	 * per-request basis. Therefore, the service distribution
++	 * enforced by the drive's internal scheduler is likely to
++	 * coincide with the desired device-throughput distribution
++	 * only in a completely symmetric scenario where:
++	 * (i)  each of these processes must get the same throughput as
++	 *      the others;
++	 * (ii) all these processes have the same I/O pattern
++	        (either sequential or random).
++	 * In fact, in such a scenario, the drive will tend to treat
++	 * the requests of each of these processes in about the same
++	 * way as the requests of the others, and thus to provide
++	 * each of these processes with about the same throughput
++	 * (which is exactly the desired throughput distribution). In
++	 * contrast, in any asymmetric scenario, device idling is
++	 * certainly needed to guarantee that bfqq receives its
++	 * assigned fraction of the device throughput (see [1] for
++	 * details).
++	 *
++	 * We address this issue by controlling, actually, only the
++	 * symmetry sub-condition (i), i.e., provided that
++	 * sub-condition (i) holds, idling is not performed,
++	 * regardless of whether sub-condition (ii) holds. In other
++	 * words, only if sub-condition (i) holds, then idling is
++	 * allowed, and the device tends to be prevented from queueing
++	 * many requests, possibly of several processes. The reason
++	 * for not controlling also sub-condition (ii) is that, first,
++	 * in the case of an HDD, the asymmetry in terms of types of
++	 * I/O patterns is already taken in to account in the above
++	 * sentinel variable
++	 * on_hdd_and_not_all_queues_seeky. Secondly, in the case of a
++	 * flash-based device, we prefer however to privilege
++	 * throughput (and idling lowers throughput for this type of
++	 * devices), for the following reasons:
++	 * 1) differently from HDDs, the service time of random
++	 *    requests is not orders of magnitudes lower than the service
++	 *    time of sequential requests; thus, even if processes doing
++	 *    sequential I/O get a preferential treatment with respect to
++	 *    others doing random I/O, the consequences are not as
++	 *    dramatic as with HDDs;
++	 * 2) if a process doing random I/O does need strong
++	 *    throughput guarantees, it is hopefully already being
++	 *    weight-raised, or the user is likely to have assigned it a
++	 *    higher weight than the other processes (and thus
++	 *    sub-condition (i) is likely to be false, which triggers
++	 *    idling).
++	 *
++	 * According to the above considerations, the next variable is
++	 * true (only) if sub-condition (i) holds. To compute the
++	 * value of this variable, we not only use the return value of
++	 * the function bfq_symmetric_scenario(), but also check
++	 * whether bfqq is being weight-raised, because
++	 * bfq_symmetric_scenario() does not take into account also
++	 * weight-raised queues (see comments to
++	 * bfq_weights_tree_add()).
++	 *
++	 * As a side note, it is worth considering that the above
++	 * device-idling countermeasures may however fail in the
++	 * following unlucky scenario: if idling is (correctly)
++	 * disabled in a time period during which all symmetry
++	 * sub-conditions hold, and hence the device is allowed to
++	 * enqueue many requests, but at some later point in time some
++	 * sub-condition stops to hold, then it may become impossible
++	 * to let requests be served in the desired order until all
++	 * the requests already queued in the device have been served.
++	 */
++	asymmetric_scenario = bfqq->wr_coeff > 1 ||
++		!bfq_symmetric_scenario(bfqd);
++
++	/*
++	 * Finally, there is a case where maximizing throughput is the
++	 * best choice even if it may cause unfairness toward
++	 * bfqq. Such a case is when bfqq became active in a burst of
++	 * queue activations. Queues that became active during a large
++	 * burst benefit only from throughput, as discussed in the
++	 * comments to bfq_handle_burst. Thus, if bfqq became active
++	 * in a burst and not idling the device maximizes throughput,
++	 * then the device must no be idled, because not idling the
++	 * device provides bfqq and all other queues in the burst with
++	 * maximum benefit. Combining this and the two cases above, we
++	 * can now establish when idling is actually needed to
++	 * preserve service guarantees.
++	 */
++	idling_needed_for_service_guarantees =
++		(on_hdd_and_not_all_queues_seeky || asymmetric_scenario) &&
++		!bfq_bfqq_in_large_burst(bfqq);
++
++	/*
++	 * We have now all the components we need to compute the return
++	 * value of the function, which is true only if both the following
++	 * conditions hold:
++	 * 1) bfqq is sync, because idling make sense only for sync queues;
++	 * 2) idling either boosts the throughput (without issues), or
++	 *    is necessary to preserve service guarantees.
++	 */
++	return bfq_bfqq_sync(bfqq) &&
++		(idling_boosts_thr_without_issues ||
++		 idling_needed_for_service_guarantees);
++}
++
++/*
++ * If the in-service queue is empty but the function bfq_bfqq_may_idle
++ * returns true, then:
++ * 1) the queue must remain in service and cannot be expired, and
++ * 2) the device must be idled to wait for the possible arrival of a new
++ *    request for the queue.
++ * See the comments to the function bfq_bfqq_may_idle for the reasons
++ * why performing device idling is the best choice to boost the throughput
++ * and preserve service guarantees when bfq_bfqq_may_idle itself
++ * returns true.
++ */
++static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
++{
++	struct bfq_data *bfqd = bfqq->bfqd;
++
++	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
++	       bfq_bfqq_may_idle(bfqq);
++}
++
++/*
++ * Select a queue for service.  If we have a current queue in service,
++ * check whether to continue servicing it, or retrieve and set a new one.
++ */
++static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
++{
++	struct bfq_queue *bfqq;
++	struct request *next_rq;
++	enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
++
++	bfqq = bfqd->in_service_queue;
++	if (!bfqq)
++		goto new_queue;
++
++	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
++
++	if (bfq_may_expire_for_budg_timeout(bfqq) &&
++	    !timer_pending(&bfqd->idle_slice_timer) &&
++	    !bfq_bfqq_must_idle(bfqq))
++		goto expire;
++
++	next_rq = bfqq->next_rq;
++	/*
++	 * If bfqq has requests queued and it has enough budget left to
++	 * serve them, keep the queue, otherwise expire it.
++	 */
++	if (next_rq) {
++		if (bfq_serv_to_charge(next_rq, bfqq) >
++			bfq_bfqq_budget_left(bfqq)) {
++			reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
++			goto expire;
++		} else {
++			/*
++			 * The idle timer may be pending because we may
++			 * not disable disk idling even when a new request
++			 * arrives.
++			 */
++			if (timer_pending(&bfqd->idle_slice_timer)) {
++				/*
++				 * If we get here: 1) at least a new request
++				 * has arrived but we have not disabled the
++				 * timer because the request was too small,
++				 * 2) then the block layer has unplugged
++				 * the device, causing the dispatch to be
++				 * invoked.
++				 *
++				 * Since the device is unplugged, now the
++				 * requests are probably large enough to
++				 * provide a reasonable throughput.
++				 * So we disable idling.
++				 */
++				bfq_clear_bfqq_wait_request(bfqq);
++				del_timer(&bfqd->idle_slice_timer);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++				bfqg_stats_update_idle_time(bfqq_group(bfqq));
++#endif
++			}
++			goto keep_queue;
++		}
++	}
++
++	/*
++	 * No requests pending. However, if the in-service queue is idling
++	 * for a new request, or has requests waiting for a completion and
++	 * may idle after their completion, then keep it anyway.
++	 */
++	if (timer_pending(&bfqd->idle_slice_timer) ||
++	    (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
++		bfqq = NULL;
++		goto keep_queue;
++	}
++
++	reason = BFQ_BFQQ_NO_MORE_REQUESTS;
++expire:
++	bfq_bfqq_expire(bfqd, bfqq, false, reason);
++new_queue:
++	bfqq = bfq_set_in_service_queue(bfqd);
++	bfq_log(bfqd, "select_queue: new queue %d returned",
++		bfqq ? bfqq->pid : 0);
++keep_queue:
++	return bfqq;
++}
++
++static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++	if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
++		bfq_log_bfqq(bfqd, bfqq,
++			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
++			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
++			jiffies_to_msecs(bfqq->wr_cur_max_time),
++			bfqq->wr_coeff,
++			bfqq->entity.weight, bfqq->entity.orig_weight);
++
++		BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
++		       entity->orig_weight * bfqq->wr_coeff);
++		if (entity->prio_changed)
++			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
++
++		/*
++		 * If the queue was activated in a burst, or
++		 * too much time has elapsed from the beginning
++		 * of this weight-raising period, then end weight
++		 * raising.
++		 */
++		if (bfq_bfqq_in_large_burst(bfqq) ||
++		    time_is_before_jiffies(bfqq->last_wr_start_finish +
++					   bfqq->wr_cur_max_time)) {
++			bfqq->last_wr_start_finish = jiffies;
++			bfq_log_bfqq(bfqd, bfqq,
++				     "wrais ending at %lu, rais_max_time %u",
++				     bfqq->last_wr_start_finish,
++				     jiffies_to_msecs(bfqq->wr_cur_max_time));
++			bfq_bfqq_end_wr(bfqq);
++		}
++	}
++	/* Update weight both if it must be raised and if it must be lowered */
++	if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
++		__bfq_entity_update_weight_prio(
++			bfq_entity_service_tree(entity),
++			entity);
++}
++
++/*
++ * Dispatch one request from bfqq, moving it to the request queue
++ * dispatch list.
++ */
++static int bfq_dispatch_request(struct bfq_data *bfqd,
++				struct bfq_queue *bfqq)
++{
++	int dispatched = 0;
++	struct request *rq;
++	unsigned long service_to_charge;
++
++	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
++
++	/* Follow expired path, else get first next available. */
++	rq = bfq_check_fifo(bfqq);
++	if (!rq)
++		rq = bfqq->next_rq;
++	service_to_charge = bfq_serv_to_charge(rq, bfqq);
++
++	if (service_to_charge > bfq_bfqq_budget_left(bfqq)) {
++		/*
++		 * This may happen if the next rq is chosen in fifo order
++		 * instead of sector order. The budget is properly
++		 * dimensioned to be always sufficient to serve the next
++		 * request only if it is chosen in sector order. The reason
++		 * is that it would be quite inefficient and little useful
++		 * to always make sure that the budget is large enough to
++		 * serve even the possible next rq in fifo order.
++		 * In fact, requests are seldom served in fifo order.
++		 *
++		 * Expire the queue for budget exhaustion, and make sure
++		 * that the next act_budget is enough to serve the next
++		 * request, even if it comes from the fifo expired path.
++		 */
++		bfqq->next_rq = rq;
++		/*
++		 * Since this dispatch is failed, make sure that
++		 * a new one will be performed
++		 */
++		if (!bfqd->rq_in_driver)
++			bfq_schedule_dispatch(bfqd);
++		goto expire;
++	}
++
++	/* Finally, insert request into driver dispatch list. */
++	bfq_bfqq_served(bfqq, service_to_charge);
++	bfq_dispatch_insert(bfqd->queue, rq);
++
++	bfq_update_wr_data(bfqd, bfqq);
++
++	bfq_log_bfqq(bfqd, bfqq,
++			"dispatched %u sec req (%llu), budg left %d",
++			blk_rq_sectors(rq),
++			(long long unsigned)blk_rq_pos(rq),
++			bfq_bfqq_budget_left(bfqq));
++
++	dispatched++;
++
++	if (!bfqd->in_service_bic) {
++		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
++		bfqd->in_service_bic = RQ_BIC(rq);
++	}
++
++	if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) &&
++	    dispatched >= bfqd->bfq_max_budget_async_rq) ||
++	    bfq_class_idle(bfqq)))
++		goto expire;
++
++	return dispatched;
++
++expire:
++	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
++	return dispatched;
++}
++
++static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
++{
++	int dispatched = 0;
++
++	while (bfqq->next_rq) {
++		bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
++		dispatched++;
++	}
++
++	BUG_ON(!list_empty(&bfqq->fifo));
++	return dispatched;
++}
++
++/*
++ * Drain our current requests.
++ * Used for barriers and when switching io schedulers on-the-fly.
++ */
++static int bfq_forced_dispatch(struct bfq_data *bfqd)
++{
++	struct bfq_queue *bfqq, *n;
++	struct bfq_service_tree *st;
++	int dispatched = 0;
++
++	bfqq = bfqd->in_service_queue;
++	if (bfqq)
++		__bfq_bfqq_expire(bfqd, bfqq);
++
++	/*
++	 * Loop through classes, and be careful to leave the scheduler
++	 * in a consistent state, as feedback mechanisms and vtime
++	 * updates cannot be disabled during the process.
++	 */
++	list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
++		st = bfq_entity_service_tree(&bfqq->entity);
++
++		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
++		bfqq->max_budget = bfq_max_budget(bfqd);
++
++		bfq_forget_idle(st);
++	}
++
++	BUG_ON(bfqd->busy_queues != 0);
++
++	return dispatched;
++}
++
++static int bfq_dispatch_requests(struct request_queue *q, int force)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct bfq_queue *bfqq;
++	int max_dispatch;
++
++	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
++	if (bfqd->busy_queues == 0)
++		return 0;
++
++	if (unlikely(force))
++		return bfq_forced_dispatch(bfqd);
++
++	bfqq = bfq_select_queue(bfqd);
++	if (!bfqq)
++		return 0;
++
++	if (bfq_class_idle(bfqq))
++		max_dispatch = 1;
++
++	if (!bfq_bfqq_sync(bfqq))
++		max_dispatch = bfqd->bfq_max_budget_async_rq;
++
++	if (!bfq_bfqq_sync(bfqq) && bfqq->dispatched >= max_dispatch) {
++		if (bfqd->busy_queues > 1)
++			return 0;
++		if (bfqq->dispatched >= 4 * max_dispatch)
++			return 0;
++	}
++
++	if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq))
++		return 0;
++
++	bfq_clear_bfqq_wait_request(bfqq);
++	BUG_ON(timer_pending(&bfqd->idle_slice_timer));
++
++	if (!bfq_dispatch_request(bfqd, bfqq))
++		return 0;
++
++	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
++			bfq_bfqq_sync(bfqq) ? "sync" : "async");
++
++	return 1;
++}
++
++/*
++ * Task holds one reference to the queue, dropped when task exits.  Each rq
++ * in-flight on this queue also holds a reference, dropped when rq is freed.
++ *
++ * Queue lock must be held here.
++ */
++static void bfq_put_queue(struct bfq_queue *bfqq)
++{
++	struct bfq_data *bfqd = bfqq->bfqd;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	struct bfq_group *bfqg = bfqq_group(bfqq);
++#endif
++
++	BUG_ON(atomic_read(&bfqq->ref) <= 0);
++
++	bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq,
++		     atomic_read(&bfqq->ref));
++	if (!atomic_dec_and_test(&bfqq->ref))
++		return;
++
++	BUG_ON(rb_first(&bfqq->sort_list));
++	BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
++	BUG_ON(bfqq->entity.tree);
++	BUG_ON(bfq_bfqq_busy(bfqq));
++	BUG_ON(bfqd->in_service_queue == bfqq);
++
++	if (bfq_bfqq_sync(bfqq))
++		/*
++		 * The fact that this queue is being destroyed does not
++		 * invalidate the fact that this queue may have been
++		 * activated during the current burst. As a consequence,
++		 * although the queue does not exist anymore, and hence
++		 * needs to be removed from the burst list if there,
++		 * the burst size has not to be decremented.
++		 */
++		hlist_del_init(&bfqq->burst_list_node);
++
++	bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq);
++
++	kmem_cache_free(bfq_pool, bfqq);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_put(bfqg);
++#endif
++}
++
++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	if (bfqq == bfqd->in_service_queue) {
++		__bfq_bfqq_expire(bfqd, bfqq);
++		bfq_schedule_dispatch(bfqd);
++	}
++
++	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq,
++		     atomic_read(&bfqq->ref));
++
++	bfq_put_queue(bfqq);
++}
++
++static void bfq_init_icq(struct io_cq *icq)
++{
++	struct bfq_io_cq *bic = icq_to_bic(icq);
++
++	bic->ttime.last_end_request = jiffies;
++}
++
++static void bfq_exit_icq(struct io_cq *icq)
++{
++	struct bfq_io_cq *bic = icq_to_bic(icq);
++	struct bfq_data *bfqd = bic_to_bfqd(bic);
++
++	if (bic->bfqq[BLK_RW_ASYNC]) {
++		bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_ASYNC]);
++		bic->bfqq[BLK_RW_ASYNC] = NULL;
++	}
++
++	if (bic->bfqq[BLK_RW_SYNC]) {
++		bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]);
++		bic->bfqq[BLK_RW_SYNC] = NULL;
++	}
++}
++
++/*
++ * Update the entity prio values; note that the new values will not
++ * be used until the next (re)activation.
++ */
++static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
++{
++	struct task_struct *tsk = current;
++	int ioprio_class;
++
++	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
++	switch (ioprio_class) {
++	default:
++		dev_err(bfqq->bfqd->queue->backing_dev_info.dev,
++			"bfq: bad prio class %d\n", ioprio_class);
++	case IOPRIO_CLASS_NONE:
++		/*
++		 * No prio set, inherit CPU scheduling settings.
++		 */
++		bfqq->new_ioprio = task_nice_ioprio(tsk);
++		bfqq->new_ioprio_class = task_nice_ioclass(tsk);
++		break;
++	case IOPRIO_CLASS_RT:
++		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
++		bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
++		break;
++	case IOPRIO_CLASS_BE:
++		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
++		bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
++		break;
++	case IOPRIO_CLASS_IDLE:
++		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
++		bfqq->new_ioprio = 7;
++		bfq_clear_bfqq_idle_window(bfqq);
++		break;
++	}
++
++	if (bfqq->new_ioprio < 0 || bfqq->new_ioprio >= IOPRIO_BE_NR) {
++		printk(KERN_CRIT "bfq_set_next_ioprio_data: new_ioprio %d\n",
++				 bfqq->new_ioprio);
++		BUG();
++	}
++
++	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
++	bfqq->entity.prio_changed = 1;
++}
++
++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
++{
++	struct bfq_data *bfqd;
++	struct bfq_queue *bfqq, *new_bfqq;
++	unsigned long uninitialized_var(flags);
++	int ioprio = bic->icq.ioc->ioprio;
++
++	bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data),
++				   &flags);
++	/*
++	 * This condition may trigger on a newly created bic, be sure to
++	 * drop the lock before returning.
++	 */
++	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
++		goto out;
++
++	bic->ioprio = ioprio;
++
++	bfqq = bic->bfqq[BLK_RW_ASYNC];
++	if (bfqq) {
++		new_bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic,
++					 GFP_ATOMIC);
++		if (new_bfqq) {
++			bic->bfqq[BLK_RW_ASYNC] = new_bfqq;
++			bfq_log_bfqq(bfqd, bfqq,
++				     "check_ioprio_change: bfqq %p %d",
++				     bfqq, atomic_read(&bfqq->ref));
++			bfq_put_queue(bfqq);
++		}
++	}
++
++	bfqq = bic->bfqq[BLK_RW_SYNC];
++	if (bfqq)
++		bfq_set_next_ioprio_data(bfqq, bic);
++
++out:
++	bfq_put_bfqd_unlock(bfqd, &flags);
++}
++
++static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++			  struct bfq_io_cq *bic, pid_t pid, int is_sync)
++{
++	RB_CLEAR_NODE(&bfqq->entity.rb_node);
++	INIT_LIST_HEAD(&bfqq->fifo);
++	INIT_HLIST_NODE(&bfqq->burst_list_node);
++
++	atomic_set(&bfqq->ref, 0);
++	bfqq->bfqd = bfqd;
++
++	if (bic)
++		bfq_set_next_ioprio_data(bfqq, bic);
++
++	if (is_sync) {
++		if (!bfq_class_idle(bfqq))
++			bfq_mark_bfqq_idle_window(bfqq);
++		bfq_mark_bfqq_sync(bfqq);
++	} else
++		bfq_clear_bfqq_sync(bfqq);
++	bfq_mark_bfqq_IO_bound(bfqq);
++
++	/* Tentative initial value to trade off between thr and lat */
++	bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
++	bfqq->pid = pid;
++
++	bfqq->wr_coeff = 1;
++	bfqq->last_wr_start_finish = 0;
++	/*
++	 * Set to the value for which bfqq will not be deemed as
++	 * soft rt when it becomes backlogged.
++	 */
++	bfqq->soft_rt_next_start = bfq_infinity_from_now(jiffies);
++}
++
++static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd,
++					      struct bio *bio, int is_sync,
++					      struct bfq_io_cq *bic,
++					      gfp_t gfp_mask)
++{
++	struct bfq_group *bfqg;
++	struct bfq_queue *bfqq, *new_bfqq = NULL;
++	struct blkcg *blkcg;
++
++retry:
++	rcu_read_lock();
++
++	blkcg = bio_blkcg(bio);
++	bfqg = bfq_find_alloc_group(bfqd, blkcg);
++	/* bic always exists here */
++	bfqq = bic_to_bfqq(bic, is_sync);
++
++	/*
++	 * Always try a new alloc if we fall back to the OOM bfqq
++	 * originally, since it should just be a temporary situation.
++	 */
++	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
++		bfqq = NULL;
++		if (new_bfqq) {
++			bfqq = new_bfqq;
++			new_bfqq = NULL;
++		} else if (gfpflags_allow_blocking(gfp_mask)) {
++			rcu_read_unlock();
++			spin_unlock_irq(bfqd->queue->queue_lock);
++			new_bfqq = kmem_cache_alloc_node(bfq_pool,
++					gfp_mask | __GFP_ZERO,
++					bfqd->queue->node);
++			spin_lock_irq(bfqd->queue->queue_lock);
++			if (new_bfqq)
++				goto retry;
++		} else {
++			bfqq = kmem_cache_alloc_node(bfq_pool,
++					gfp_mask | __GFP_ZERO,
++					bfqd->queue->node);
++		}
++
++		if (bfqq) {
++			bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
++                                      is_sync);
++			bfq_init_entity(&bfqq->entity, bfqg);
++			bfq_log_bfqq(bfqd, bfqq, "allocated");
++		} else {
++			bfqq = &bfqd->oom_bfqq;
++			bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
++		}
++	}
++
++	if (new_bfqq)
++		kmem_cache_free(bfq_pool, new_bfqq);
++
++	rcu_read_unlock();
++
++	return bfqq;
++}
++
++static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
++					       struct bfq_group *bfqg,
++					       int ioprio_class, int ioprio)
++{
++	switch (ioprio_class) {
++	case IOPRIO_CLASS_RT:
++		return &bfqg->async_bfqq[0][ioprio];
++	case IOPRIO_CLASS_NONE:
++		ioprio = IOPRIO_NORM;
++		/* fall through */
++	case IOPRIO_CLASS_BE:
++		return &bfqg->async_bfqq[1][ioprio];
++	case IOPRIO_CLASS_IDLE:
++		return &bfqg->async_idle_bfqq;
++	default:
++		BUG();
++	}
++}
++
++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
++				       struct bio *bio, int is_sync,
++				       struct bfq_io_cq *bic, gfp_t gfp_mask)
++{
++	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
++	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
++	struct bfq_queue **async_bfqq = NULL;
++	struct bfq_queue *bfqq = NULL;
++
++	if (!is_sync) {
++		struct blkcg *blkcg;
++		struct bfq_group *bfqg;
++
++		rcu_read_lock();
++		blkcg = bio_blkcg(bio);
++		rcu_read_unlock();
++		bfqg = bfq_find_alloc_group(bfqd, blkcg);
++		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
++						  ioprio);
++		bfqq = *async_bfqq;
++	}
++
++	if (!bfqq)
++		bfqq = bfq_find_alloc_queue(bfqd, bio, is_sync, bic, gfp_mask);
++
++	/*
++	 * Pin the queue now that it's allocated, scheduler exit will
++	 * prune it.
++	 */
++	if (!is_sync && !(*async_bfqq)) {
++		atomic_inc(&bfqq->ref);
++		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
++			     bfqq, atomic_read(&bfqq->ref));
++		*async_bfqq = bfqq;
++	}
++
++	atomic_inc(&bfqq->ref);
++	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq,
++		     atomic_read(&bfqq->ref));
++	return bfqq;
++}
++
++static void bfq_update_io_thinktime(struct bfq_data *bfqd,
++				    struct bfq_io_cq *bic)
++{
++	unsigned long elapsed = jiffies - bic->ttime.last_end_request;
++	unsigned long ttime = min(elapsed, 2UL * bfqd->bfq_slice_idle);
++
++	bic->ttime.ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
++	bic->ttime.ttime_total = (7*bic->ttime.ttime_total + 256*ttime) / 8;
++	bic->ttime.ttime_mean = (bic->ttime.ttime_total + 128) /
++				bic->ttime.ttime_samples;
++}
++
++static void bfq_update_io_seektime(struct bfq_data *bfqd,
++				   struct bfq_queue *bfqq,
++				   struct request *rq)
++{
++	sector_t sdist;
++	u64 total;
++
++	if (bfqq->last_request_pos < blk_rq_pos(rq))
++		sdist = blk_rq_pos(rq) - bfqq->last_request_pos;
++	else
++		sdist = bfqq->last_request_pos - blk_rq_pos(rq);
++
++	/*
++	 * Don't allow the seek distance to get too large from the
++	 * odd fragment, pagein, etc.
++	 */
++	if (bfqq->seek_samples == 0) /* first request, not really a seek */
++		sdist = 0;
++	else if (bfqq->seek_samples <= 60) /* second & third seek */
++		sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024);
++	else
++		sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64);
++
++	bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8;
++	bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8;
++	total = bfqq->seek_total + (bfqq->seek_samples/2);
++	do_div(total, bfqq->seek_samples);
++	bfqq->seek_mean = (sector_t)total;
++
++	bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist,
++			(u64)bfqq->seek_mean);
++}
++
++/*
++ * Disable idle window if the process thinks too long or seeks so much that
++ * it doesn't matter.
++ */
++static void bfq_update_idle_window(struct bfq_data *bfqd,
++				   struct bfq_queue *bfqq,
++				   struct bfq_io_cq *bic)
++{
++	int enable_idle;
++
++	/* Don't idle for async or idle io prio class. */
++	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
++		return;
++
++	enable_idle = bfq_bfqq_idle_window(bfqq);
++
++	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
++	    bfqd->bfq_slice_idle == 0 ||
++		(bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
++			bfqq->wr_coeff == 1))
++		enable_idle = 0;
++	else if (bfq_sample_valid(bic->ttime.ttime_samples)) {
++		if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle &&
++			bfqq->wr_coeff == 1)
++			enable_idle = 0;
++		else
++			enable_idle = 1;
++	}
++	bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
++		enable_idle);
++
++	if (enable_idle)
++		bfq_mark_bfqq_idle_window(bfqq);
++	else
++		bfq_clear_bfqq_idle_window(bfqq);
++}
++
++/*
++ * Called when a new fs request (rq) is added to bfqq.  Check if there's
++ * something we should do about it.
++ */
++static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++			    struct request *rq)
++{
++	struct bfq_io_cq *bic = RQ_BIC(rq);
++
++	if (rq->cmd_flags & REQ_META)
++		bfqq->meta_pending++;
++
++	bfq_update_io_thinktime(bfqd, bic);
++	bfq_update_io_seektime(bfqd, bfqq, rq);
++	if (!BFQQ_SEEKY(bfqq) && bfq_bfqq_constantly_seeky(bfqq)) {
++		bfq_clear_bfqq_constantly_seeky(bfqq);
++		if (!blk_queue_nonrot(bfqd->queue)) {
++			BUG_ON(!bfqd->const_seeky_busy_in_flight_queues);
++			bfqd->const_seeky_busy_in_flight_queues--;
++		}
++	}
++	if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
++	    !BFQQ_SEEKY(bfqq))
++		bfq_update_idle_window(bfqd, bfqq, bic);
++
++	bfq_log_bfqq(bfqd, bfqq,
++		     "rq_enqueued: idle_window=%d (seeky %d, mean %llu)",
++		     bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq),
++		     (long long unsigned)bfqq->seek_mean);
++
++	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
++
++	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
++		bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
++				 blk_rq_sectors(rq) < 32;
++		bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
++
++		/*
++		 * There is just this request queued: if the request
++		 * is small and the queue is not to be expired, then
++		 * just exit.
++		 *
++		 * In this way, if the disk is being idled to wait for
++		 * a new request from the in-service queue, we avoid
++		 * unplugging the device and committing the disk to serve
++		 * just a small request. On the contrary, we wait for
++		 * the block layer to decide when to unplug the device:
++		 * hopefully, new requests will be merged to this one
++		 * quickly, then the device will be unplugged and
++		 * larger requests will be dispatched.
++		 */
++		if (small_req && !budget_timeout)
++			return;
++
++		/*
++		 * A large enough request arrived, or the queue is to
++		 * be expired: in both cases disk idling is to be
++		 * stopped, so clear wait_request flag and reset
++		 * timer.
++		 */
++		bfq_clear_bfqq_wait_request(bfqq);
++		del_timer(&bfqd->idle_slice_timer);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		bfqg_stats_update_idle_time(bfqq_group(bfqq));
++#endif
++
++		/*
++		 * The queue is not empty, because a new request just
++		 * arrived. Hence we can safely expire the queue, in
++		 * case of budget timeout, without risking that the
++		 * timestamps of the queue are not updated correctly.
++		 * See [1] for more details.
++		 */
++		if (budget_timeout)
++			bfq_bfqq_expire(bfqd, bfqq, false,
++					BFQ_BFQQ_BUDGET_TIMEOUT);
++
++		/*
++		 * Let the request rip immediately, or let a new queue be
++		 * selected if bfqq has just been expired.
++		 */
++		__blk_run_queue(bfqd->queue);
++	}
++}
++
++static void bfq_insert_request(struct request_queue *q, struct request *rq)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++
++	assert_spin_locked(bfqd->queue->queue_lock);
++
++	bfq_add_request(rq);
++
++	rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
++	list_add_tail(&rq->queuelist, &bfqq->fifo);
++
++	bfq_rq_enqueued(bfqd, bfqq, rq);
++}
++
++static void bfq_update_hw_tag(struct bfq_data *bfqd)
++{
++	bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver,
++				     bfqd->rq_in_driver);
++
++	if (bfqd->hw_tag == 1)
++		return;
++
++	/*
++	 * This sample is valid if the number of outstanding requests
++	 * is large enough to allow a queueing behavior.  Note that the
++	 * sum is not exact, as it's not taking into account deactivated
++	 * requests.
++	 */
++	if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
++		return;
++
++	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
++		return;
++
++	bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
++	bfqd->max_rq_in_driver = 0;
++	bfqd->hw_tag_samples = 0;
++}
++
++static void bfq_completed_request(struct request_queue *q, struct request *rq)
++{
++	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++	struct bfq_data *bfqd = bfqq->bfqd;
++	bool sync = bfq_bfqq_sync(bfqq);
++
++	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left (%d)",
++		     blk_rq_sectors(rq), sync);
++
++	bfq_update_hw_tag(bfqd);
++
++	BUG_ON(!bfqd->rq_in_driver);
++	BUG_ON(!bfqq->dispatched);
++	bfqd->rq_in_driver--;
++	bfqq->dispatched--;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_update_completion(bfqq_group(bfqq),
++				     rq_start_time_ns(rq),
++				     rq_io_start_time_ns(rq), rq->cmd_flags);
++#endif
++
++	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
++		bfq_weights_tree_remove(bfqd, &bfqq->entity,
++					&bfqd->queue_weights_tree);
++		if (!blk_queue_nonrot(bfqd->queue)) {
++			BUG_ON(!bfqd->busy_in_flight_queues);
++			bfqd->busy_in_flight_queues--;
++			if (bfq_bfqq_constantly_seeky(bfqq)) {
++				BUG_ON(!bfqd->
++					const_seeky_busy_in_flight_queues);
++				bfqd->const_seeky_busy_in_flight_queues--;
++			}
++		}
++	}
++
++	if (sync) {
++		bfqd->sync_flight--;
++		RQ_BIC(rq)->ttime.last_end_request = jiffies;
++	}
++
++	/*
++	 * If we are waiting to discover whether the request pattern of the
++	 * task associated with the queue is actually isochronous, and
++	 * both requisites for this condition to hold are satisfied, then
++	 * compute soft_rt_next_start (see the comments to the function
++	 * bfq_bfqq_softrt_next_start()).
++	 */
++	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
++	    RB_EMPTY_ROOT(&bfqq->sort_list))
++		bfqq->soft_rt_next_start =
++			bfq_bfqq_softrt_next_start(bfqd, bfqq);
++
++	/*
++	 * If this is the in-service queue, check if it needs to be expired,
++	 * or if we want to idle in case it has no pending requests.
++	 */
++	if (bfqd->in_service_queue == bfqq) {
++		if (bfq_bfqq_budget_new(bfqq))
++			bfq_set_budget_timeout(bfqd);
++
++		if (bfq_bfqq_must_idle(bfqq)) {
++			bfq_arm_slice_timer(bfqd);
++			goto out;
++		} else if (bfq_may_expire_for_budg_timeout(bfqq))
++			bfq_bfqq_expire(bfqd, bfqq, false,
++					BFQ_BFQQ_BUDGET_TIMEOUT);
++		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
++			 (bfqq->dispatched == 0 ||
++			  !bfq_bfqq_may_idle(bfqq)))
++			bfq_bfqq_expire(bfqd, bfqq, false,
++					BFQ_BFQQ_NO_MORE_REQUESTS);
++	}
++
++	if (!bfqd->rq_in_driver)
++		bfq_schedule_dispatch(bfqd);
++
++out:
++	return;
++}
++
++static int __bfq_may_queue(struct bfq_queue *bfqq)
++{
++	if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
++		bfq_clear_bfqq_must_alloc(bfqq);
++		return ELV_MQUEUE_MUST;
++	}
++
++	return ELV_MQUEUE_MAY;
++}
++
++static int bfq_may_queue(struct request_queue *q, int rw)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct task_struct *tsk = current;
++	struct bfq_io_cq *bic;
++	struct bfq_queue *bfqq;
++
++	/*
++	 * Don't force setup of a queue from here, as a call to may_queue
++	 * does not necessarily imply that a request actually will be
++	 * queued. So just lookup a possibly existing queue, or return
++	 * 'may queue' if that fails.
++	 */
++	bic = bfq_bic_lookup(bfqd, tsk->io_context);
++	if (!bic)
++		return ELV_MQUEUE_MAY;
++
++	bfqq = bic_to_bfqq(bic, rw_is_sync(rw));
++	if (bfqq)
++		return __bfq_may_queue(bfqq);
++
++	return ELV_MQUEUE_MAY;
++}
++
++/*
++ * Queue lock held here.
++ */
++static void bfq_put_request(struct request *rq)
++{
++	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++
++	if (bfqq) {
++		const int rw = rq_data_dir(rq);
++
++		BUG_ON(!bfqq->allocated[rw]);
++		bfqq->allocated[rw]--;
++
++		rq->elv.priv[0] = NULL;
++		rq->elv.priv[1] = NULL;
++
++		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
++			     bfqq, atomic_read(&bfqq->ref));
++		bfq_put_queue(bfqq);
++	}
++}
++
++/*
++ * Allocate bfq data structures associated with this request.
++ */
++static int bfq_set_request(struct request_queue *q, struct request *rq,
++			   struct bio *bio, gfp_t gfp_mask)
++{
++	struct bfq_data *bfqd = q->elevator->elevator_data;
++	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
++	const int rw = rq_data_dir(rq);
++	const int is_sync = rq_is_sync(rq);
++	struct bfq_queue *bfqq;
++	unsigned long flags;
++
++	might_sleep_if(gfpflags_allow_blocking(gfp_mask));
++
++	bfq_check_ioprio_change(bic, bio);
++
++	spin_lock_irqsave(q->queue_lock, flags);
++
++	if (!bic)
++		goto queue_fail;
++
++	bfq_bic_update_cgroup(bic, bio);
++
++	bfqq = bic_to_bfqq(bic, is_sync);
++	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
++		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask);
++		bic_set_bfqq(bic, bfqq, is_sync);
++		if (is_sync) {
++			if (bfqd->large_burst)
++				bfq_mark_bfqq_in_large_burst(bfqq);
++			else
++				bfq_clear_bfqq_in_large_burst(bfqq);
++		}
++	}
++
++	bfqq->allocated[rw]++;
++	atomic_inc(&bfqq->ref);
++	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq,
++		     atomic_read(&bfqq->ref));
++
++	rq->elv.priv[0] = bic;
++	rq->elv.priv[1] = bfqq;
++
++	spin_unlock_irqrestore(q->queue_lock, flags);
++
++	return 0;
++
++queue_fail:
++	bfq_schedule_dispatch(bfqd);
++	spin_unlock_irqrestore(q->queue_lock, flags);
++
++	return 1;
++}
++
++static void bfq_kick_queue(struct work_struct *work)
++{
++	struct bfq_data *bfqd =
++		container_of(work, struct bfq_data, unplug_work);
++	struct request_queue *q = bfqd->queue;
++
++	spin_lock_irq(q->queue_lock);
++	__blk_run_queue(q);
++	spin_unlock_irq(q->queue_lock);
++}
++
++/*
++ * Handler of the expiration of the timer running if the in-service queue
++ * is idling inside its time slice.
++ */
++static void bfq_idle_slice_timer(unsigned long data)
++{
++	struct bfq_data *bfqd = (struct bfq_data *)data;
++	struct bfq_queue *bfqq;
++	unsigned long flags;
++	enum bfqq_expiration reason;
++
++	spin_lock_irqsave(bfqd->queue->queue_lock, flags);
++
++	bfqq = bfqd->in_service_queue;
++	/*
++	 * Theoretical race here: the in-service queue can be NULL or
++	 * different from the queue that was idling if the timer handler
++	 * spins on the queue_lock and a new request arrives for the
++	 * current queue and there is a full dispatch cycle that changes
++	 * the in-service queue.  This can hardly happen, but in the worst
++	 * case we just expire a queue too early.
++	 */
++	if (bfqq) {
++		bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
++		if (bfq_bfqq_budget_timeout(bfqq))
++			/*
++			 * Also here the queue can be safely expired
++			 * for budget timeout without wasting
++			 * guarantees
++			 */
++			reason = BFQ_BFQQ_BUDGET_TIMEOUT;
++		else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
++			/*
++			 * The queue may not be empty upon timer expiration,
++			 * because we may not disable the timer when the
++			 * first request of the in-service queue arrives
++			 * during disk idling.
++			 */
++			reason = BFQ_BFQQ_TOO_IDLE;
++		else
++			goto schedule_dispatch;
++
++		bfq_bfqq_expire(bfqd, bfqq, true, reason);
++	}
++
++schedule_dispatch:
++	bfq_schedule_dispatch(bfqd);
++
++	spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
++}
++
++static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
++{
++	del_timer_sync(&bfqd->idle_slice_timer);
++	cancel_work_sync(&bfqd->unplug_work);
++}
++
++static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
++					struct bfq_queue **bfqq_ptr)
++{
++	struct bfq_group *root_group = bfqd->root_group;
++	struct bfq_queue *bfqq = *bfqq_ptr;
++
++	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
++	if (bfqq) {
++		bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group);
++		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
++			     bfqq, atomic_read(&bfqq->ref));
++		bfq_put_queue(bfqq);
++		*bfqq_ptr = NULL;
++	}
++}
++
++/*
++ * Release all the bfqg references to its async queues.  If we are
++ * deallocating the group these queues may still contain requests, so
++ * we reparent them to the root cgroup (i.e., the only one that will
++ * exist for sure until all the requests on a device are gone).
++ */
++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
++{
++	int i, j;
++
++	for (i = 0; i < 2; i++)
++		for (j = 0; j < IOPRIO_BE_NR; j++)
++			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
++
++	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
++}
++
++static void bfq_exit_queue(struct elevator_queue *e)
++{
++	struct bfq_data *bfqd = e->elevator_data;
++	struct request_queue *q = bfqd->queue;
++	struct bfq_queue *bfqq, *n;
++
++	bfq_shutdown_timer_wq(bfqd);
++
++	spin_lock_irq(q->queue_lock);
++
++	BUG_ON(bfqd->in_service_queue);
++	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
++		bfq_deactivate_bfqq(bfqd, bfqq, 0);
++
++	spin_unlock_irq(q->queue_lock);
++
++	bfq_shutdown_timer_wq(bfqd);
++
++	synchronize_rcu();
++
++	BUG_ON(timer_pending(&bfqd->idle_slice_timer));
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
++#else
++	kfree(bfqd->root_group);
++#endif
++
++	kfree(bfqd);
++}
++
++static void bfq_init_root_group(struct bfq_group *root_group,
++				struct bfq_data *bfqd)
++{
++	int i;
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	root_group->entity.parent = NULL;
++	root_group->my_entity = NULL;
++	root_group->bfqd = bfqd;
++#endif
++	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
++		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
++}
++
++static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
++{
++	struct bfq_data *bfqd;
++	struct elevator_queue *eq;
++
++	eq = elevator_alloc(q, e);
++	if (!eq)
++		return -ENOMEM;
++
++	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
++	if (!bfqd) {
++		kobject_put(&eq->kobj);
++		return -ENOMEM;
++	}
++	eq->elevator_data = bfqd;
++
++	/*
++	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
++	 * Grab a permanent reference to it, so that the normal code flow
++	 * will not attempt to free it.
++	 */
++	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
++	atomic_inc(&bfqd->oom_bfqq.ref);
++	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
++	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
++	bfqd->oom_bfqq.entity.new_weight =
++		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
++	/*
++	 * Trigger weight initialization, according to ioprio, at the
++	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
++	 * class won't be changed any more.
++	 */
++	bfqd->oom_bfqq.entity.prio_changed = 1;
++
++	bfqd->queue = q;
++
++	spin_lock_irq(q->queue_lock);
++	q->elevator = eq;
++	spin_unlock_irq(q->queue_lock);
++
++	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
++	if (!bfqd->root_group)
++		goto out_free;
++	bfq_init_root_group(bfqd->root_group, bfqd);
++	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqd->active_numerous_groups = 0;
++#endif
++
++	init_timer(&bfqd->idle_slice_timer);
++	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
++	bfqd->idle_slice_timer.data = (unsigned long)bfqd;
++
++	bfqd->queue_weights_tree = RB_ROOT;
++	bfqd->group_weights_tree = RB_ROOT;
++
++	INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
++
++	INIT_LIST_HEAD(&bfqd->active_list);
++	INIT_LIST_HEAD(&bfqd->idle_list);
++	INIT_HLIST_HEAD(&bfqd->burst_list);
++
++	bfqd->hw_tag = -1;
++
++	bfqd->bfq_max_budget = bfq_default_max_budget;
++
++	bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
++	bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
++	bfqd->bfq_back_max = bfq_back_max;
++	bfqd->bfq_back_penalty = bfq_back_penalty;
++	bfqd->bfq_slice_idle = bfq_slice_idle;
++	bfqd->bfq_class_idle_last_service = 0;
++	bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq;
++	bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async;
++	bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync;
++
++	bfqd->bfq_requests_within_timer = 120;
++
++	bfqd->bfq_large_burst_thresh = 11;
++	bfqd->bfq_burst_interval = msecs_to_jiffies(500);
++
++	bfqd->low_latency = true;
++
++	bfqd->bfq_wr_coeff = 20;
++	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
++	bfqd->bfq_wr_max_time = 0;
++	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
++	bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
++	bfqd->bfq_wr_max_softrt_rate = 7000; /*
++					      * Approximate rate required
++					      * to playback or record a
++					      * high-definition compressed
++					      * video.
++					      */
++	bfqd->wr_busy_queues = 0;
++	bfqd->busy_in_flight_queues = 0;
++	bfqd->const_seeky_busy_in_flight_queues = 0;
++
++	/*
++	 * Begin by assuming, optimistically, that the device peak rate is
++	 * equal to the highest reference rate.
++	 */
++	bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
++			T_fast[blk_queue_nonrot(bfqd->queue)];
++	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)];
++	bfqd->device_speed = BFQ_BFQD_FAST;
++
++	return 0;
++
++out_free:
++	kfree(bfqd);
++	kobject_put(&eq->kobj);
++	return -ENOMEM;
++}
++
++static void bfq_slab_kill(void)
++{
++	if (bfq_pool)
++		kmem_cache_destroy(bfq_pool);
++}
++
++static int __init bfq_slab_setup(void)
++{
++	bfq_pool = KMEM_CACHE(bfq_queue, 0);
++	if (!bfq_pool)
++		return -ENOMEM;
++	return 0;
++}
++
++static ssize_t bfq_var_show(unsigned int var, char *page)
++{
++	return sprintf(page, "%d\n", var);
++}
++
++static ssize_t bfq_var_store(unsigned long *var, const char *page,
++			     size_t count)
++{
++	unsigned long new_val;
++	int ret = kstrtoul(page, 10, &new_val);
++
++	if (ret == 0)
++		*var = new_val;
++
++	return count;
++}
++
++static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
++{
++	struct bfq_data *bfqd = e->elevator_data;
++	return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
++		       jiffies_to_msecs(bfqd->bfq_wr_max_time) :
++		       jiffies_to_msecs(bfq_wr_duration(bfqd)));
++}
++
++static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
++{
++	struct bfq_queue *bfqq;
++	struct bfq_data *bfqd = e->elevator_data;
++	ssize_t num_char = 0;
++
++	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
++			    bfqd->queued);
++
++	spin_lock_irq(bfqd->queue->queue_lock);
++
++	num_char += sprintf(page + num_char, "Active:\n");
++	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
++	  num_char += sprintf(page + num_char,
++			      "pid%d: weight %hu, nr_queued %d %d, dur %d/%u\n",
++			      bfqq->pid,
++			      bfqq->entity.weight,
++			      bfqq->queued[0],
++			      bfqq->queued[1],
++			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
++			jiffies_to_msecs(bfqq->wr_cur_max_time));
++	}
++
++	num_char += sprintf(page + num_char, "Idle:\n");
++	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
++			num_char += sprintf(page + num_char,
++				"pid%d: weight %hu, dur %d/%u\n",
++				bfqq->pid,
++				bfqq->entity.weight,
++				jiffies_to_msecs(jiffies -
++					bfqq->last_wr_start_finish),
++				jiffies_to_msecs(bfqq->wr_cur_max_time));
++	}
++
++	spin_unlock_irq(bfqd->queue->queue_lock);
++
++	return num_char;
++}
++
++#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
++static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
++{									\
++	struct bfq_data *bfqd = e->elevator_data;			\
++	unsigned int __data = __VAR;					\
++	if (__CONV)							\
++		__data = jiffies_to_msecs(__data);			\
++	return bfq_var_show(__data, (page));				\
++}
++SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 1);
++SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 1);
++SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
++SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
++SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1);
++SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
++SHOW_FUNCTION(bfq_max_budget_async_rq_show,
++	      bfqd->bfq_max_budget_async_rq, 0);
++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1);
++SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1);
++SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
++SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
++SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
++SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
++SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
++	1);
++SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
++#undef SHOW_FUNCTION
++
++#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
++static ssize_t								\
++__FUNC(struct elevator_queue *e, const char *page, size_t count)	\
++{									\
++	struct bfq_data *bfqd = e->elevator_data;			\
++	unsigned long uninitialized_var(__data);			\
++	int ret = bfq_var_store(&__data, (page), count);		\
++	if (__data < (MIN))						\
++		__data = (MIN);						\
++	else if (__data > (MAX))					\
++		__data = (MAX);						\
++	if (__CONV)							\
++		*(__PTR) = msecs_to_jiffies(__data);			\
++	else								\
++		*(__PTR) = __data;					\
++	return ret;							\
++}
++STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
++		INT_MAX, 1);
++STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
++		INT_MAX, 1);
++STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
++STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
++		INT_MAX, 0);
++STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1);
++STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq,
++		1, INT_MAX, 0);
++STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0,
++		INT_MAX, 1);
++STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
++STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
++STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
++		1);
++STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
++		INT_MAX, 1);
++STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
++		&bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
++STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
++		INT_MAX, 0);
++#undef STORE_FUNCTION
++
++/* do nothing for the moment */
++static ssize_t bfq_weights_store(struct elevator_queue *e,
++				    const char *page, size_t count)
++{
++	return count;
++}
++
++static unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd)
++{
++	u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
++
++	if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES)
++		return bfq_calc_max_budget(bfqd->peak_rate, timeout);
++	else
++		return bfq_default_max_budget;
++}
++
++static ssize_t bfq_max_budget_store(struct elevator_queue *e,
++				    const char *page, size_t count)
++{
++	struct bfq_data *bfqd = e->elevator_data;
++	unsigned long uninitialized_var(__data);
++	int ret = bfq_var_store(&__data, (page), count);
++
++	if (__data == 0)
++		bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
++	else {
++		if (__data > INT_MAX)
++			__data = INT_MAX;
++		bfqd->bfq_max_budget = __data;
++	}
++
++	bfqd->bfq_user_max_budget = __data;
++
++	return ret;
++}
++
++static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
++				      const char *page, size_t count)
++{
++	struct bfq_data *bfqd = e->elevator_data;
++	unsigned long uninitialized_var(__data);
++	int ret = bfq_var_store(&__data, (page), count);
++
++	if (__data < 1)
++		__data = 1;
++	else if (__data > INT_MAX)
++		__data = INT_MAX;
++
++	bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data);
++	if (bfqd->bfq_user_max_budget == 0)
++		bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
++
++	return ret;
++}
++
++static ssize_t bfq_low_latency_store(struct elevator_queue *e,
++				     const char *page, size_t count)
++{
++	struct bfq_data *bfqd = e->elevator_data;
++	unsigned long uninitialized_var(__data);
++	int ret = bfq_var_store(&__data, (page), count);
++
++	if (__data > 1)
++		__data = 1;
++	if (__data == 0 && bfqd->low_latency != 0)
++		bfq_end_wr(bfqd);
++	bfqd->low_latency = __data;
++
++	return ret;
++}
++
++#define BFQ_ATTR(name) \
++	__ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
++
++static struct elv_fs_entry bfq_attrs[] = {
++	BFQ_ATTR(fifo_expire_sync),
++	BFQ_ATTR(fifo_expire_async),
++	BFQ_ATTR(back_seek_max),
++	BFQ_ATTR(back_seek_penalty),
++	BFQ_ATTR(slice_idle),
++	BFQ_ATTR(max_budget),
++	BFQ_ATTR(max_budget_async_rq),
++	BFQ_ATTR(timeout_sync),
++	BFQ_ATTR(timeout_async),
++	BFQ_ATTR(low_latency),
++	BFQ_ATTR(wr_coeff),
++	BFQ_ATTR(wr_max_time),
++	BFQ_ATTR(wr_rt_max_time),
++	BFQ_ATTR(wr_min_idle_time),
++	BFQ_ATTR(wr_min_inter_arr_async),
++	BFQ_ATTR(wr_max_softrt_rate),
++	BFQ_ATTR(weights),
++	__ATTR_NULL
++};
++
++static struct elevator_type iosched_bfq = {
++	.ops = {
++		.elevator_merge_fn =		bfq_merge,
++		.elevator_merged_fn =		bfq_merged_request,
++		.elevator_merge_req_fn =	bfq_merged_requests,
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		.elevator_bio_merged_fn =	bfq_bio_merged,
++#endif
++		.elevator_allow_merge_fn =	bfq_allow_merge,
++		.elevator_dispatch_fn =		bfq_dispatch_requests,
++		.elevator_add_req_fn =		bfq_insert_request,
++		.elevator_activate_req_fn =	bfq_activate_request,
++		.elevator_deactivate_req_fn =	bfq_deactivate_request,
++		.elevator_completed_req_fn =	bfq_completed_request,
++		.elevator_former_req_fn =	elv_rb_former_request,
++		.elevator_latter_req_fn =	elv_rb_latter_request,
++		.elevator_init_icq_fn =		bfq_init_icq,
++		.elevator_exit_icq_fn =		bfq_exit_icq,
++		.elevator_set_req_fn =		bfq_set_request,
++		.elevator_put_req_fn =		bfq_put_request,
++		.elevator_may_queue_fn =	bfq_may_queue,
++		.elevator_init_fn =		bfq_init_queue,
++		.elevator_exit_fn =		bfq_exit_queue,
++	},
++	.icq_size =		sizeof(struct bfq_io_cq),
++	.icq_align =		__alignof__(struct bfq_io_cq),
++	.elevator_attrs =	bfq_attrs,
++	.elevator_name =	"bfq",
++	.elevator_owner =	THIS_MODULE,
++};
++
++static int __init bfq_init(void)
++{
++	int ret;
++
++	/*
++	 * Can be 0 on HZ < 1000 setups.
++	 */
++	if (bfq_slice_idle == 0)
++		bfq_slice_idle = 1;
++
++	if (bfq_timeout_async == 0)
++		bfq_timeout_async = 1;
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	ret = blkcg_policy_register(&blkcg_policy_bfq);
++	if (ret)
++		return ret;
++#endif
++
++	ret = -ENOMEM;
++	if (bfq_slab_setup())
++		goto err_pol_unreg;
++
++	/*
++	 * Times to load large popular applications for the typical systems
++	 * installed on the reference devices (see the comments before the
++	 * definitions of the two arrays).
++	 */
++	T_slow[0] = msecs_to_jiffies(2600);
++	T_slow[1] = msecs_to_jiffies(1000);
++	T_fast[0] = msecs_to_jiffies(5500);
++	T_fast[1] = msecs_to_jiffies(2000);
++
++	/*
++	 * Thresholds that determine the switch between speed classes (see
++	 * the comments before the definition of the array).
++	 */
++	device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2;
++	device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2;
++
++	ret = elv_register(&iosched_bfq);
++	if (ret)
++		goto err_pol_unreg;
++
++	pr_info("BFQ I/O-scheduler: v7r11");
++
++	return 0;
++
++err_pol_unreg:
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	blkcg_policy_unregister(&blkcg_policy_bfq);
++#endif
++	return ret;
++}
++
++static void __exit bfq_exit(void)
++{
++	elv_unregister(&iosched_bfq);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	blkcg_policy_unregister(&blkcg_policy_bfq);
++#endif
++	bfq_slab_kill();
++}
++
++module_init(bfq_init);
++module_exit(bfq_exit);
++
++MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
++MODULE_LICENSE("GPL");
+diff --git a/block/bfq-sched.c b/block/bfq-sched.c
+new file mode 100644
+index 0000000..a64fec1
+--- /dev/null
++++ b/block/bfq-sched.c
+@@ -0,0 +1,1200 @@
++/*
++ * BFQ: Hierarchical B-WF2Q+ scheduler.
++ *
++ * Based on ideas and code from CFQ:
++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
++ *
++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
++ *		      Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ */
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++#define for_each_entity(entity)	\
++	for (; entity ; entity = entity->parent)
++
++#define for_each_entity_safe(entity, parent) \
++	for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
++
++
++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
++						 int extract,
++						 struct bfq_data *bfqd);
++
++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
++
++static void bfq_update_budget(struct bfq_entity *next_in_service)
++{
++	struct bfq_entity *bfqg_entity;
++	struct bfq_group *bfqg;
++	struct bfq_sched_data *group_sd;
++
++	BUG_ON(!next_in_service);
++
++	group_sd = next_in_service->sched_data;
++
++	bfqg = container_of(group_sd, struct bfq_group, sched_data);
++	/*
++	 * bfq_group's my_entity field is not NULL only if the group
++	 * is not the root group. We must not touch the root entity
++	 * as it must never become an in-service entity.
++	 */
++	bfqg_entity = bfqg->my_entity;
++	if (bfqg_entity)
++		bfqg_entity->budget = next_in_service->budget;
++}
++
++static int bfq_update_next_in_service(struct bfq_sched_data *sd)
++{
++	struct bfq_entity *next_in_service;
++
++	if (sd->in_service_entity)
++		/* will update/requeue at the end of service */
++		return 0;
++
++	/*
++	 * NOTE: this can be improved in many ways, such as returning
++	 * 1 (and thus propagating upwards the update) only when the
++	 * budget changes, or caching the bfqq that will be scheduled
++	 * next from this subtree.  By now we worry more about
++	 * correctness than about performance...
++	 */
++	next_in_service = bfq_lookup_next_entity(sd, 0, NULL);
++	sd->next_in_service = next_in_service;
++
++	if (next_in_service)
++		bfq_update_budget(next_in_service);
++
++	return 1;
++}
++
++static void bfq_check_next_in_service(struct bfq_sched_data *sd,
++				      struct bfq_entity *entity)
++{
++	BUG_ON(sd->next_in_service != entity);
++}
++#else
++#define for_each_entity(entity)	\
++	for (; entity ; entity = NULL)
++
++#define for_each_entity_safe(entity, parent) \
++	for (parent = NULL; entity ; entity = parent)
++
++static int bfq_update_next_in_service(struct bfq_sched_data *sd)
++{
++	return 0;
++}
++
++static void bfq_check_next_in_service(struct bfq_sched_data *sd,
++				      struct bfq_entity *entity)
++{
++}
++
++static void bfq_update_budget(struct bfq_entity *next_in_service)
++{
++}
++#endif
++
++/*
++ * Shift for timestamp calculations.  This actually limits the maximum
++ * service allowed in one timestamp delta (small shift values increase it),
++ * the maximum total weight that can be used for the queues in the system
++ * (big shift values increase it), and the period of virtual time
++ * wraparounds.
++ */
++#define WFQ_SERVICE_SHIFT	22
++
++/**
++ * bfq_gt - compare two timestamps.
++ * @a: first ts.
++ * @b: second ts.
++ *
++ * Return @a > @b, dealing with wrapping correctly.
++ */
++static int bfq_gt(u64 a, u64 b)
++{
++	return (s64)(a - b) > 0;
++}
++
++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = NULL;
++
++	BUG_ON(!entity);
++
++	if (!entity->my_sched_data)
++		bfqq = container_of(entity, struct bfq_queue, entity);
++
++	return bfqq;
++}
++
++
++/**
++ * bfq_delta - map service into the virtual time domain.
++ * @service: amount of service.
++ * @weight: scale factor (weight of an entity or weight sum).
++ */
++static u64 bfq_delta(unsigned long service, unsigned long weight)
++{
++	u64 d = (u64)service << WFQ_SERVICE_SHIFT;
++
++	do_div(d, weight);
++	return d;
++}
++
++/**
++ * bfq_calc_finish - assign the finish time to an entity.
++ * @entity: the entity to act upon.
++ * @service: the service to be charged to the entity.
++ */
++static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++
++	BUG_ON(entity->weight == 0);
++
++	entity->finish = entity->start +
++		bfq_delta(service, entity->weight);
++
++	if (bfqq) {
++		bfq_log_bfqq(bfqq->bfqd, bfqq,
++			"calc_finish: serv %lu, w %d",
++			service, entity->weight);
++		bfq_log_bfqq(bfqq->bfqd, bfqq,
++			"calc_finish: start %llu, finish %llu, delta %llu",
++			entity->start, entity->finish,
++			bfq_delta(service, entity->weight));
++	}
++}
++
++/**
++ * bfq_entity_of - get an entity from a node.
++ * @node: the node field of the entity.
++ *
++ * Convert a node pointer to the relative entity.  This is used only
++ * to simplify the logic of some functions and not as the generic
++ * conversion mechanism because, e.g., in the tree walking functions,
++ * the check for a %NULL value would be redundant.
++ */
++static struct bfq_entity *bfq_entity_of(struct rb_node *node)
++{
++	struct bfq_entity *entity = NULL;
++
++	if (node)
++		entity = rb_entry(node, struct bfq_entity, rb_node);
++
++	return entity;
++}
++
++/**
++ * bfq_extract - remove an entity from a tree.
++ * @root: the tree root.
++ * @entity: the entity to remove.
++ */
++static void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
++{
++	BUG_ON(entity->tree != root);
++
++	entity->tree = NULL;
++	rb_erase(&entity->rb_node, root);
++}
++
++/**
++ * bfq_idle_extract - extract an entity from the idle tree.
++ * @st: the service tree of the owning @entity.
++ * @entity: the entity being removed.
++ */
++static void bfq_idle_extract(struct bfq_service_tree *st,
++			     struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	struct rb_node *next;
++
++	BUG_ON(entity->tree != &st->idle);
++
++	if (entity == st->first_idle) {
++		next = rb_next(&entity->rb_node);
++		st->first_idle = bfq_entity_of(next);
++	}
++
++	if (entity == st->last_idle) {
++		next = rb_prev(&entity->rb_node);
++		st->last_idle = bfq_entity_of(next);
++	}
++
++	bfq_extract(&st->idle, entity);
++
++	if (bfqq)
++		list_del(&bfqq->bfqq_list);
++}
++
++/**
++ * bfq_insert - generic tree insertion.
++ * @root: tree root.
++ * @entity: entity to insert.
++ *
++ * This is used for the idle and the active tree, since they are both
++ * ordered by finish time.
++ */
++static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
++{
++	struct bfq_entity *entry;
++	struct rb_node **node = &root->rb_node;
++	struct rb_node *parent = NULL;
++
++	BUG_ON(entity->tree);
++
++	while (*node) {
++		parent = *node;
++		entry = rb_entry(parent, struct bfq_entity, rb_node);
++
++		if (bfq_gt(entry->finish, entity->finish))
++			node = &parent->rb_left;
++		else
++			node = &parent->rb_right;
++	}
++
++	rb_link_node(&entity->rb_node, parent, node);
++	rb_insert_color(&entity->rb_node, root);
++
++	entity->tree = root;
++}
++
++/**
++ * bfq_update_min - update the min_start field of a entity.
++ * @entity: the entity to update.
++ * @node: one of its children.
++ *
++ * This function is called when @entity may store an invalid value for
++ * min_start due to updates to the active tree.  The function  assumes
++ * that the subtree rooted at @node (which may be its left or its right
++ * child) has a valid min_start value.
++ */
++static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
++{
++	struct bfq_entity *child;
++
++	if (node) {
++		child = rb_entry(node, struct bfq_entity, rb_node);
++		if (bfq_gt(entity->min_start, child->min_start))
++			entity->min_start = child->min_start;
++	}
++}
++
++/**
++ * bfq_update_active_node - recalculate min_start.
++ * @node: the node to update.
++ *
++ * @node may have changed position or one of its children may have moved,
++ * this function updates its min_start value.  The left and right subtrees
++ * are assumed to hold a correct min_start value.
++ */
++static void bfq_update_active_node(struct rb_node *node)
++{
++	struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
++
++	entity->min_start = entity->start;
++	bfq_update_min(entity, node->rb_right);
++	bfq_update_min(entity, node->rb_left);
++}
++
++/**
++ * bfq_update_active_tree - update min_start for the whole active tree.
++ * @node: the starting node.
++ *
++ * @node must be the deepest modified node after an update.  This function
++ * updates its min_start using the values held by its children, assuming
++ * that they did not change, and then updates all the nodes that may have
++ * changed in the path to the root.  The only nodes that may have changed
++ * are the ones in the path or their siblings.
++ */
++static void bfq_update_active_tree(struct rb_node *node)
++{
++	struct rb_node *parent;
++
++up:
++	bfq_update_active_node(node);
++
++	parent = rb_parent(node);
++	if (!parent)
++		return;
++
++	if (node == parent->rb_left && parent->rb_right)
++		bfq_update_active_node(parent->rb_right);
++	else if (parent->rb_left)
++		bfq_update_active_node(parent->rb_left);
++
++	node = parent;
++	goto up;
++}
++
++static void bfq_weights_tree_add(struct bfq_data *bfqd,
++				 struct bfq_entity *entity,
++				 struct rb_root *root);
++
++static void bfq_weights_tree_remove(struct bfq_data *bfqd,
++				    struct bfq_entity *entity,
++				    struct rb_root *root);
++
++
++/**
++ * bfq_active_insert - insert an entity in the active tree of its
++ *                     group/device.
++ * @st: the service tree of the entity.
++ * @entity: the entity being inserted.
++ *
++ * The active tree is ordered by finish time, but an extra key is kept
++ * per each node, containing the minimum value for the start times of
++ * its children (and the node itself), so it's possible to search for
++ * the eligible node with the lowest finish time in logarithmic time.
++ */
++static void bfq_active_insert(struct bfq_service_tree *st,
++			      struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	struct rb_node *node = &entity->rb_node;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	struct bfq_sched_data *sd = NULL;
++	struct bfq_group *bfqg = NULL;
++	struct bfq_data *bfqd = NULL;
++#endif
++
++	bfq_insert(&st->active, entity);
++
++	if (node->rb_left)
++		node = node->rb_left;
++	else if (node->rb_right)
++		node = node->rb_right;
++
++	bfq_update_active_tree(node);
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	sd = entity->sched_data;
++	bfqg = container_of(sd, struct bfq_group, sched_data);
++	BUG_ON(!bfqg);
++	bfqd = (struct bfq_data *)bfqg->bfqd;
++#endif
++	if (bfqq)
++		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	else { /* bfq_group */
++		BUG_ON(!bfqd);
++		bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
++	}
++	if (bfqg != bfqd->root_group) {
++		BUG_ON(!bfqg);
++		BUG_ON(!bfqd);
++		bfqg->active_entities++;
++		if (bfqg->active_entities == 2)
++			bfqd->active_numerous_groups++;
++	}
++#endif
++}
++
++/**
++ * bfq_ioprio_to_weight - calc a weight from an ioprio.
++ * @ioprio: the ioprio value to convert.
++ */
++static unsigned short bfq_ioprio_to_weight(int ioprio)
++{
++	BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
++	return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - ioprio;
++}
++
++/**
++ * bfq_weight_to_ioprio - calc an ioprio from a weight.
++ * @weight: the weight value to convert.
++ *
++ * To preserve as much as possible the old only-ioprio user interface,
++ * 0 is used as an escape ioprio value for weights (numerically) equal or
++ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
++ */
++static unsigned short bfq_weight_to_ioprio(int weight)
++{
++	BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
++	return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ?
++		0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight;
++}
++
++static void bfq_get_entity(struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++
++	if (bfqq) {
++		atomic_inc(&bfqq->ref);
++		bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
++			     bfqq, atomic_read(&bfqq->ref));
++	}
++}
++
++/**
++ * bfq_find_deepest - find the deepest node that an extraction can modify.
++ * @node: the node being removed.
++ *
++ * Do the first step of an extraction in an rb tree, looking for the
++ * node that will replace @node, and returning the deepest node that
++ * the following modifications to the tree can touch.  If @node is the
++ * last node in the tree return %NULL.
++ */
++static struct rb_node *bfq_find_deepest(struct rb_node *node)
++{
++	struct rb_node *deepest;
++
++	if (!node->rb_right && !node->rb_left)
++		deepest = rb_parent(node);
++	else if (!node->rb_right)
++		deepest = node->rb_left;
++	else if (!node->rb_left)
++		deepest = node->rb_right;
++	else {
++		deepest = rb_next(node);
++		if (deepest->rb_right)
++			deepest = deepest->rb_right;
++		else if (rb_parent(deepest) != node)
++			deepest = rb_parent(deepest);
++	}
++
++	return deepest;
++}
++
++/**
++ * bfq_active_extract - remove an entity from the active tree.
++ * @st: the service_tree containing the tree.
++ * @entity: the entity being removed.
++ */
++static void bfq_active_extract(struct bfq_service_tree *st,
++			       struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	struct rb_node *node;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	struct bfq_sched_data *sd = NULL;
++	struct bfq_group *bfqg = NULL;
++	struct bfq_data *bfqd = NULL;
++#endif
++
++	node = bfq_find_deepest(&entity->rb_node);
++	bfq_extract(&st->active, entity);
++
++	if (node)
++		bfq_update_active_tree(node);
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	sd = entity->sched_data;
++	bfqg = container_of(sd, struct bfq_group, sched_data);
++	BUG_ON(!bfqg);
++	bfqd = (struct bfq_data *)bfqg->bfqd;
++#endif
++	if (bfqq)
++		list_del(&bfqq->bfqq_list);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	else { /* bfq_group */
++		BUG_ON(!bfqd);
++		bfq_weights_tree_remove(bfqd, entity,
++					&bfqd->group_weights_tree);
++	}
++	if (bfqg != bfqd->root_group) {
++		BUG_ON(!bfqg);
++		BUG_ON(!bfqd);
++		BUG_ON(!bfqg->active_entities);
++		bfqg->active_entities--;
++		if (bfqg->active_entities == 1) {
++			BUG_ON(!bfqd->active_numerous_groups);
++			bfqd->active_numerous_groups--;
++		}
++	}
++#endif
++}
++
++/**
++ * bfq_idle_insert - insert an entity into the idle tree.
++ * @st: the service tree containing the tree.
++ * @entity: the entity to insert.
++ */
++static void bfq_idle_insert(struct bfq_service_tree *st,
++			    struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	struct bfq_entity *first_idle = st->first_idle;
++	struct bfq_entity *last_idle = st->last_idle;
++
++	if (!first_idle || bfq_gt(first_idle->finish, entity->finish))
++		st->first_idle = entity;
++	if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
++		st->last_idle = entity;
++
++	bfq_insert(&st->idle, entity);
++
++	if (bfqq)
++		list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
++}
++
++/**
++ * bfq_forget_entity - remove an entity from the wfq trees.
++ * @st: the service tree.
++ * @entity: the entity being removed.
++ *
++ * Update the device status and forget everything about @entity, putting
++ * the device reference to it, if it is a queue.  Entities belonging to
++ * groups are not refcounted.
++ */
++static void bfq_forget_entity(struct bfq_service_tree *st,
++			      struct bfq_entity *entity)
++{
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	struct bfq_sched_data *sd;
++
++	BUG_ON(!entity->on_st);
++
++	entity->on_st = 0;
++	st->wsum -= entity->weight;
++	if (bfqq) {
++		sd = entity->sched_data;
++		bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d",
++			     bfqq, atomic_read(&bfqq->ref));
++		bfq_put_queue(bfqq);
++	}
++}
++
++/**
++ * bfq_put_idle_entity - release the idle tree ref of an entity.
++ * @st: service tree for the entity.
++ * @entity: the entity being released.
++ */
++static void bfq_put_idle_entity(struct bfq_service_tree *st,
++				struct bfq_entity *entity)
++{
++	bfq_idle_extract(st, entity);
++	bfq_forget_entity(st, entity);
++}
++
++/**
++ * bfq_forget_idle - update the idle tree if necessary.
++ * @st: the service tree to act upon.
++ *
++ * To preserve the global O(log N) complexity we only remove one entry here;
++ * as the idle tree will not grow indefinitely this can be done safely.
++ */
++static void bfq_forget_idle(struct bfq_service_tree *st)
++{
++	struct bfq_entity *first_idle = st->first_idle;
++	struct bfq_entity *last_idle = st->last_idle;
++
++	if (RB_EMPTY_ROOT(&st->active) && last_idle &&
++	    !bfq_gt(last_idle->finish, st->vtime)) {
++		/*
++		 * Forget the whole idle tree, increasing the vtime past
++		 * the last finish time of idle entities.
++		 */
++		st->vtime = last_idle->finish;
++	}
++
++	if (first_idle && !bfq_gt(first_idle->finish, st->vtime))
++		bfq_put_idle_entity(st, first_idle);
++}
++
++static struct bfq_service_tree *
++__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
++			 struct bfq_entity *entity)
++{
++	struct bfq_service_tree *new_st = old_st;
++
++	if (entity->prio_changed) {
++		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++		unsigned short prev_weight, new_weight;
++		struct bfq_data *bfqd = NULL;
++		struct rb_root *root;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		struct bfq_sched_data *sd;
++		struct bfq_group *bfqg;
++#endif
++
++		if (bfqq)
++			bfqd = bfqq->bfqd;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		else {
++			sd = entity->my_sched_data;
++			bfqg = container_of(sd, struct bfq_group, sched_data);
++			BUG_ON(!bfqg);
++			bfqd = (struct bfq_data *)bfqg->bfqd;
++			BUG_ON(!bfqd);
++		}
++#endif
++
++		BUG_ON(old_st->wsum < entity->weight);
++		old_st->wsum -= entity->weight;
++
++		if (entity->new_weight != entity->orig_weight) {
++			if (entity->new_weight < BFQ_MIN_WEIGHT ||
++			    entity->new_weight > BFQ_MAX_WEIGHT) {
++				printk(KERN_CRIT "update_weight_prio: "
++						 "new_weight %d\n",
++					entity->new_weight);
++				BUG();
++			}
++			entity->orig_weight = entity->new_weight;
++			if (bfqq)
++				bfqq->ioprio =
++				  bfq_weight_to_ioprio(entity->orig_weight);
++		}
++
++		if (bfqq)
++			bfqq->ioprio_class = bfqq->new_ioprio_class;
++		entity->prio_changed = 0;
++
++		/*
++		 * NOTE: here we may be changing the weight too early,
++		 * this will cause unfairness.  The correct approach
++		 * would have required additional complexity to defer
++		 * weight changes to the proper time instants (i.e.,
++		 * when entity->finish <= old_st->vtime).
++		 */
++		new_st = bfq_entity_service_tree(entity);
++
++		prev_weight = entity->weight;
++		new_weight = entity->orig_weight *
++			     (bfqq ? bfqq->wr_coeff : 1);
++		/*
++		 * If the weight of the entity changes, remove the entity
++		 * from its old weight counter (if there is a counter
++		 * associated with the entity), and add it to the counter
++		 * associated with its new weight.
++		 */
++		if (prev_weight != new_weight) {
++			root = bfqq ? &bfqd->queue_weights_tree :
++				      &bfqd->group_weights_tree;
++			bfq_weights_tree_remove(bfqd, entity, root);
++		}
++		entity->weight = new_weight;
++		/*
++		 * Add the entity to its weights tree only if it is
++		 * not associated with a weight-raised queue.
++		 */
++		if (prev_weight != new_weight &&
++		    (bfqq ? bfqq->wr_coeff == 1 : 1))
++			/* If we get here, root has been initialized. */
++			bfq_weights_tree_add(bfqd, entity, root);
++
++		new_st->wsum += entity->weight;
++
++		if (new_st != old_st)
++			entity->start = new_st->vtime;
++	}
++
++	return new_st;
++}
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
++#endif
++
++/**
++ * bfq_bfqq_served - update the scheduler status after selection for
++ *                   service.
++ * @bfqq: the queue being served.
++ * @served: bytes to transfer.
++ *
++ * NOTE: this can be optimized, as the timestamps of upper level entities
++ * are synchronized every time a new bfqq is selected for service.  By now,
++ * we keep it to better check consistency.
++ */
++static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++	struct bfq_service_tree *st;
++
++	for_each_entity(entity) {
++		st = bfq_entity_service_tree(entity);
++
++		entity->service += served;
++		BUG_ON(entity->service > entity->budget);
++		BUG_ON(st->wsum == 0);
++
++		st->vtime += bfq_delta(served, st->wsum);
++		bfq_forget_idle(st);
++	}
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
++#endif
++	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served);
++}
++
++/**
++ * bfq_bfqq_charge_full_budget - set the service to the entity budget.
++ * @bfqq: the queue that needs a service update.
++ *
++ * When it's not possible to be fair in the service domain, because
++ * a queue is not consuming its budget fast enough (the meaning of
++ * fast depends on the timeout parameter), we charge it a full
++ * budget.  In this way we should obtain a sort of time-domain
++ * fairness among all the seeky/slow queues.
++ */
++static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++
++	bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget");
++
++	bfq_bfqq_served(bfqq, entity->budget - entity->service);
++}
++
++/**
++ * __bfq_activate_entity - activate an entity.
++ * @entity: the entity being activated.
++ *
++ * Called whenever an entity is activated, i.e., it is not active and one
++ * of its children receives a new request, or has to be reactivated due to
++ * budget exhaustion.  It uses the current budget of the entity (and the
++ * service received if @entity is active) of the queue to calculate its
++ * timestamps.
++ */
++static void __bfq_activate_entity(struct bfq_entity *entity)
++{
++	struct bfq_sched_data *sd = entity->sched_data;
++	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
++
++	if (entity == sd->in_service_entity) {
++		BUG_ON(entity->tree);
++		/*
++		 * If we are requeueing the current entity we have
++		 * to take care of not charging to it service it has
++		 * not received.
++		 */
++		bfq_calc_finish(entity, entity->service);
++		entity->start = entity->finish;
++		sd->in_service_entity = NULL;
++	} else if (entity->tree == &st->active) {
++		/*
++		 * Requeueing an entity due to a change of some
++		 * next_in_service entity below it.  We reuse the
++		 * old start time.
++		 */
++		bfq_active_extract(st, entity);
++	} else if (entity->tree == &st->idle) {
++		/*
++		 * Must be on the idle tree, bfq_idle_extract() will
++		 * check for that.
++		 */
++		bfq_idle_extract(st, entity);
++		entity->start = bfq_gt(st->vtime, entity->finish) ?
++				       st->vtime : entity->finish;
++	} else {
++		/*
++		 * The finish time of the entity may be invalid, and
++		 * it is in the past for sure, otherwise the queue
++		 * would have been on the idle tree.
++		 */
++		entity->start = st->vtime;
++		st->wsum += entity->weight;
++		bfq_get_entity(entity);
++
++		BUG_ON(entity->on_st);
++		entity->on_st = 1;
++	}
++
++	st = __bfq_entity_update_weight_prio(st, entity);
++	bfq_calc_finish(entity, entity->budget);
++	bfq_active_insert(st, entity);
++}
++
++/**
++ * bfq_activate_entity - activate an entity and its ancestors if necessary.
++ * @entity: the entity to activate.
++ *
++ * Activate @entity and all the entities on the path from it to the root.
++ */
++static void bfq_activate_entity(struct bfq_entity *entity)
++{
++	struct bfq_sched_data *sd;
++
++	for_each_entity(entity) {
++		__bfq_activate_entity(entity);
++
++		sd = entity->sched_data;
++		if (!bfq_update_next_in_service(sd))
++			/*
++			 * No need to propagate the activation to the
++			 * upper entities, as they will be updated when
++			 * the in-service entity is rescheduled.
++			 */
++			break;
++	}
++}
++
++/**
++ * __bfq_deactivate_entity - deactivate an entity from its service tree.
++ * @entity: the entity to deactivate.
++ * @requeue: if false, the entity will not be put into the idle tree.
++ *
++ * Deactivate an entity, independently from its previous state.  If the
++ * entity was not on a service tree just return, otherwise if it is on
++ * any scheduler tree, extract it from that tree, and if necessary
++ * and if the caller did not specify @requeue, put it on the idle tree.
++ *
++ * Return %1 if the caller should update the entity hierarchy, i.e.,
++ * if the entity was in service or if it was the next_in_service for
++ * its sched_data; return %0 otherwise.
++ */
++static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
++{
++	struct bfq_sched_data *sd = entity->sched_data;
++	struct bfq_service_tree *st;
++	int was_in_service;
++	int ret = 0;
++
++	if (sd == NULL || !entity->on_st) /* never activated, or inactive */
++		return 0;
++
++	st = bfq_entity_service_tree(entity);
++	was_in_service = entity == sd->in_service_entity;
++
++	BUG_ON(was_in_service && entity->tree);
++
++	if (was_in_service) {
++		bfq_calc_finish(entity, entity->service);
++		sd->in_service_entity = NULL;
++	} else if (entity->tree == &st->active)
++		bfq_active_extract(st, entity);
++	else if (entity->tree == &st->idle)
++		bfq_idle_extract(st, entity);
++	else if (entity->tree)
++		BUG();
++
++	if (was_in_service || sd->next_in_service == entity)
++		ret = bfq_update_next_in_service(sd);
++
++	if (!requeue || !bfq_gt(entity->finish, st->vtime))
++		bfq_forget_entity(st, entity);
++	else
++		bfq_idle_insert(st, entity);
++
++	BUG_ON(sd->in_service_entity == entity);
++	BUG_ON(sd->next_in_service == entity);
++
++	return ret;
++}
++
++/**
++ * bfq_deactivate_entity - deactivate an entity.
++ * @entity: the entity to deactivate.
++ * @requeue: true if the entity can be put on the idle tree
++ */
++static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
++{
++	struct bfq_sched_data *sd;
++	struct bfq_entity *parent;
++
++	for_each_entity_safe(entity, parent) {
++		sd = entity->sched_data;
++
++		if (!__bfq_deactivate_entity(entity, requeue))
++			/*
++			 * The parent entity is still backlogged, and
++			 * we don't need to update it as it is still
++			 * in service.
++			 */
++			break;
++
++		if (sd->next_in_service)
++			/*
++			 * The parent entity is still backlogged and
++			 * the budgets on the path towards the root
++			 * need to be updated.
++			 */
++			goto update;
++
++		/*
++		 * If we reach there the parent is no more backlogged and
++		 * we want to propagate the dequeue upwards.
++		 */
++		requeue = 1;
++	}
++
++	return;
++
++update:
++	entity = parent;
++	for_each_entity(entity) {
++		__bfq_activate_entity(entity);
++
++		sd = entity->sched_data;
++		if (!bfq_update_next_in_service(sd))
++			break;
++	}
++}
++
++/**
++ * bfq_update_vtime - update vtime if necessary.
++ * @st: the service tree to act upon.
++ *
++ * If necessary update the service tree vtime to have at least one
++ * eligible entity, skipping to its start time.  Assumes that the
++ * active tree of the device is not empty.
++ *
++ * NOTE: this hierarchical implementation updates vtimes quite often,
++ * we may end up with reactivated processes getting timestamps after a
++ * vtime skip done because we needed a ->first_active entity on some
++ * intermediate node.
++ */
++static void bfq_update_vtime(struct bfq_service_tree *st)
++{
++	struct bfq_entity *entry;
++	struct rb_node *node = st->active.rb_node;
++
++	entry = rb_entry(node, struct bfq_entity, rb_node);
++	if (bfq_gt(entry->min_start, st->vtime)) {
++		st->vtime = entry->min_start;
++		bfq_forget_idle(st);
++	}
++}
++
++/**
++ * bfq_first_active_entity - find the eligible entity with
++ *                           the smallest finish time
++ * @st: the service tree to select from.
++ *
++ * This function searches the first schedulable entity, starting from the
++ * root of the tree and going on the left every time on this side there is
++ * a subtree with at least one eligible (start >= vtime) entity. The path on
++ * the right is followed only if a) the left subtree contains no eligible
++ * entities and b) no eligible entity has been found yet.
++ */
++static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st)
++{
++	struct bfq_entity *entry, *first = NULL;
++	struct rb_node *node = st->active.rb_node;
++
++	while (node) {
++		entry = rb_entry(node, struct bfq_entity, rb_node);
++left:
++		if (!bfq_gt(entry->start, st->vtime))
++			first = entry;
++
++		BUG_ON(bfq_gt(entry->min_start, st->vtime));
++
++		if (node->rb_left) {
++			entry = rb_entry(node->rb_left,
++					 struct bfq_entity, rb_node);
++			if (!bfq_gt(entry->min_start, st->vtime)) {
++				node = node->rb_left;
++				goto left;
++			}
++		}
++		if (first)
++			break;
++		node = node->rb_right;
++	}
++
++	BUG_ON(!first && !RB_EMPTY_ROOT(&st->active));
++	return first;
++}
++
++/**
++ * __bfq_lookup_next_entity - return the first eligible entity in @st.
++ * @st: the service tree.
++ *
++ * Update the virtual time in @st and return the first eligible entity
++ * it contains.
++ */
++static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st,
++						   bool force)
++{
++	struct bfq_entity *entity, *new_next_in_service = NULL;
++
++	if (RB_EMPTY_ROOT(&st->active))
++		return NULL;
++
++	bfq_update_vtime(st);
++	entity = bfq_first_active_entity(st);
++	BUG_ON(bfq_gt(entity->start, st->vtime));
++
++	/*
++	 * If the chosen entity does not match with the sched_data's
++	 * next_in_service and we are forcedly serving the IDLE priority
++	 * class tree, bubble up budget update.
++	 */
++	if (unlikely(force && entity != entity->sched_data->next_in_service)) {
++		new_next_in_service = entity;
++		for_each_entity(new_next_in_service)
++			bfq_update_budget(new_next_in_service);
++	}
++
++	return entity;
++}
++
++/**
++ * bfq_lookup_next_entity - return the first eligible entity in @sd.
++ * @sd: the sched_data.
++ * @extract: if true the returned entity will be also extracted from @sd.
++ *
++ * NOTE: since we cache the next_in_service entity at each level of the
++ * hierarchy, the complexity of the lookup can be decreased with
++ * absolutely no effort just returning the cached next_in_service value;
++ * we prefer to do full lookups to test the consistency of * the data
++ * structures.
++ */
++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
++						 int extract,
++						 struct bfq_data *bfqd)
++{
++	struct bfq_service_tree *st = sd->service_tree;
++	struct bfq_entity *entity;
++	int i = 0;
++
++	BUG_ON(sd->in_service_entity);
++
++	if (bfqd &&
++	    jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) {
++		entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1,
++						  true);
++		if (entity) {
++			i = BFQ_IOPRIO_CLASSES - 1;
++			bfqd->bfq_class_idle_last_service = jiffies;
++			sd->next_in_service = entity;
++		}
++	}
++	for (; i < BFQ_IOPRIO_CLASSES; i++) {
++		entity = __bfq_lookup_next_entity(st + i, false);
++		if (entity) {
++			if (extract) {
++				bfq_check_next_in_service(sd, entity);
++				bfq_active_extract(st + i, entity);
++				sd->in_service_entity = entity;
++				sd->next_in_service = NULL;
++			}
++			break;
++		}
++	}
++
++	return entity;
++}
++
++/*
++ * Get next queue for service.
++ */
++static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
++{
++	struct bfq_entity *entity = NULL;
++	struct bfq_sched_data *sd;
++	struct bfq_queue *bfqq;
++
++	BUG_ON(bfqd->in_service_queue);
++
++	if (bfqd->busy_queues == 0)
++		return NULL;
++
++	sd = &bfqd->root_group->sched_data;
++	for (; sd ; sd = entity->my_sched_data) {
++		entity = bfq_lookup_next_entity(sd, 1, bfqd);
++		BUG_ON(!entity);
++		entity->service = 0;
++	}
++
++	bfqq = bfq_entity_to_bfqq(entity);
++	BUG_ON(!bfqq);
++
++	return bfqq;
++}
++
++static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
++{
++	if (bfqd->in_service_bic) {
++		put_io_context(bfqd->in_service_bic->icq.ioc);
++		bfqd->in_service_bic = NULL;
++	}
++
++	bfqd->in_service_queue = NULL;
++	del_timer(&bfqd->idle_slice_timer);
++}
++
++static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++				int requeue)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++
++	if (bfqq == bfqd->in_service_queue)
++		__bfq_bfqd_reset_in_service(bfqd);
++
++	bfq_deactivate_entity(entity, requeue);
++}
++
++static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++
++	bfq_activate_entity(entity);
++}
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
++#endif
++
++/*
++ * Called when the bfqq no longer has requests pending, remove it from
++ * the service tree.
++ */
++static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++			      int requeue)
++{
++	BUG_ON(!bfq_bfqq_busy(bfqq));
++	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
++
++	bfq_log_bfqq(bfqd, bfqq, "del from busy");
++
++	bfq_clear_bfqq_busy(bfqq);
++
++	BUG_ON(bfqd->busy_queues == 0);
++	bfqd->busy_queues--;
++
++	if (!bfqq->dispatched) {
++		bfq_weights_tree_remove(bfqd, &bfqq->entity,
++					&bfqd->queue_weights_tree);
++		if (!blk_queue_nonrot(bfqd->queue)) {
++			BUG_ON(!bfqd->busy_in_flight_queues);
++			bfqd->busy_in_flight_queues--;
++			if (bfq_bfqq_constantly_seeky(bfqq)) {
++				BUG_ON(!bfqd->
++					const_seeky_busy_in_flight_queues);
++				bfqd->const_seeky_busy_in_flight_queues--;
++			}
++		}
++	}
++	if (bfqq->wr_coeff > 1)
++		bfqd->wr_busy_queues--;
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	bfqg_stats_update_dequeue(bfqq_group(bfqq));
++#endif
++
++	bfq_deactivate_bfqq(bfqd, bfqq, requeue);
++}
++
++/*
++ * Called when an inactive queue receives a new request.
++ */
++static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	BUG_ON(bfq_bfqq_busy(bfqq));
++	BUG_ON(bfqq == bfqd->in_service_queue);
++
++	bfq_log_bfqq(bfqd, bfqq, "add to busy");
++
++	bfq_activate_bfqq(bfqd, bfqq);
++
++	bfq_mark_bfqq_busy(bfqq);
++	bfqd->busy_queues++;
++
++	if (!bfqq->dispatched) {
++		if (bfqq->wr_coeff == 1)
++			bfq_weights_tree_add(bfqd, &bfqq->entity,
++					     &bfqd->queue_weights_tree);
++		if (!blk_queue_nonrot(bfqd->queue)) {
++			bfqd->busy_in_flight_queues++;
++			if (bfq_bfqq_constantly_seeky(bfqq))
++				bfqd->const_seeky_busy_in_flight_queues++;
++		}
++	}
++	if (bfqq->wr_coeff > 1)
++		bfqd->wr_busy_queues++;
++}
+diff --git a/block/bfq.h b/block/bfq.h
+new file mode 100644
+index 0000000..485d0c9
+--- /dev/null
++++ b/block/bfq.h
+@@ -0,0 +1,801 @@
++/*
++ * BFQ-v7r11 for 4.5.0: data structures and common functions prototypes.
++ *
++ * Based on ideas and code from CFQ:
++ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
++ *
++ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
++ *		      Paolo Valente <paolo.valente@unimore.it>
++ *
++ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ */
++
++#ifndef _BFQ_H
++#define _BFQ_H
++
++#include <linux/blktrace_api.h>
++#include <linux/hrtimer.h>
++#include <linux/ioprio.h>
++#include <linux/rbtree.h>
++#include <linux/blk-cgroup.h>
++
++#define BFQ_IOPRIO_CLASSES	3
++#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
++
++#define BFQ_MIN_WEIGHT			1
++#define BFQ_MAX_WEIGHT			1000
++#define BFQ_WEIGHT_CONVERSION_COEFF	10
++
++#define BFQ_DEFAULT_QUEUE_IOPRIO	4
++
++#define BFQ_DEFAULT_GRP_WEIGHT	10
++#define BFQ_DEFAULT_GRP_IOPRIO	0
++#define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
++
++struct bfq_entity;
++
++/**
++ * struct bfq_service_tree - per ioprio_class service tree.
++ * @active: tree for active entities (i.e., those backlogged).
++ * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i).
++ * @first_idle: idle entity with minimum F_i.
++ * @last_idle: idle entity with maximum F_i.
++ * @vtime: scheduler virtual time.
++ * @wsum: scheduler weight sum; active and idle entities contribute to it.
++ *
++ * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
++ * ioprio_class has its own independent scheduler, and so its own
++ * bfq_service_tree.  All the fields are protected by the queue lock
++ * of the containing bfqd.
++ */
++struct bfq_service_tree {
++	struct rb_root active;
++	struct rb_root idle;
++
++	struct bfq_entity *first_idle;
++	struct bfq_entity *last_idle;
++
++	u64 vtime;
++	unsigned long wsum;
++};
++
++/**
++ * struct bfq_sched_data - multi-class scheduler.
++ * @in_service_entity: entity in service.
++ * @next_in_service: head-of-the-line entity in the scheduler.
++ * @service_tree: array of service trees, one per ioprio_class.
++ *
++ * bfq_sched_data is the basic scheduler queue.  It supports three
++ * ioprio_classes, and can be used either as a toplevel queue or as
++ * an intermediate queue on a hierarchical setup.
++ * @next_in_service points to the active entity of the sched_data
++ * service trees that will be scheduled next.
++ *
++ * The supported ioprio_classes are the same as in CFQ, in descending
++ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
++ * Requests from higher priority queues are served before all the
++ * requests from lower priority queues; among requests of the same
++ * queue requests are served according to B-WF2Q+.
++ * All the fields are protected by the queue lock of the containing bfqd.
++ */
++struct bfq_sched_data {
++	struct bfq_entity *in_service_entity;
++	struct bfq_entity *next_in_service;
++	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
++};
++
++/**
++ * struct bfq_weight_counter - counter of the number of all active entities
++ *                             with a given weight.
++ * @weight: weight of the entities that this counter refers to.
++ * @num_active: number of active entities with this weight.
++ * @weights_node: weights tree member (see bfq_data's @queue_weights_tree
++ *                and @group_weights_tree).
++ */
++struct bfq_weight_counter {
++	short int weight;
++	unsigned int num_active;
++	struct rb_node weights_node;
++};
++
++/**
++ * struct bfq_entity - schedulable entity.
++ * @rb_node: service_tree member.
++ * @weight_counter: pointer to the weight counter associated with this entity.
++ * @on_st: flag, true if the entity is on a tree (either the active or
++ *         the idle one of its service_tree).
++ * @finish: B-WF2Q+ finish timestamp (aka F_i).
++ * @start: B-WF2Q+ start timestamp (aka S_i).
++ * @tree: tree the entity is enqueued into; %NULL if not on a tree.
++ * @min_start: minimum start time of the (active) subtree rooted at
++ *             this entity; used for O(log N) lookups into active trees.
++ * @service: service received during the last round of service.
++ * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight.
++ * @weight: weight of the queue
++ * @parent: parent entity, for hierarchical scheduling.
++ * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the
++ *                 associated scheduler queue, %NULL on leaf nodes.
++ * @sched_data: the scheduler queue this entity belongs to.
++ * @ioprio: the ioprio in use.
++ * @new_weight: when a weight change is requested, the new weight value.
++ * @orig_weight: original weight, used to implement weight boosting
++ * @prio_changed: flag, true when the user requested a weight, ioprio or
++ *		  ioprio_class change.
++ *
++ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
++ * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
++ * entity belongs to the sched_data of the parent group in the cgroup
++ * hierarchy.  Non-leaf entities have also their own sched_data, stored
++ * in @my_sched_data.
++ *
++ * Each entity stores independently its priority values; this would
++ * allow different weights on different devices, but this
++ * functionality is not exported to userspace by now.  Priorities and
++ * weights are updated lazily, first storing the new values into the
++ * new_* fields, then setting the @prio_changed flag.  As soon as
++ * there is a transition in the entity state that allows the priority
++ * update to take place the effective and the requested priority
++ * values are synchronized.
++ *
++ * Unless cgroups are used, the weight value is calculated from the
++ * ioprio to export the same interface as CFQ.  When dealing with
++ * ``well-behaved'' queues (i.e., queues that do not spend too much
++ * time to consume their budget and have true sequential behavior, and
++ * when there are no external factors breaking anticipation) the
++ * relative weights at each level of the cgroups hierarchy should be
++ * guaranteed.  All the fields are protected by the queue lock of the
++ * containing bfqd.
++ */
++struct bfq_entity {
++	struct rb_node rb_node;
++	struct bfq_weight_counter *weight_counter;
++
++	int on_st;
++
++	u64 finish;
++	u64 start;
++
++	struct rb_root *tree;
++
++	u64 min_start;
++
++	int service, budget;
++	unsigned short weight, new_weight;
++	unsigned short orig_weight;
++
++	struct bfq_entity *parent;
++
++	struct bfq_sched_data *my_sched_data;
++	struct bfq_sched_data *sched_data;
++
++	int prio_changed;
++};
++
++struct bfq_group;
++
++/**
++ * struct bfq_queue - leaf schedulable entity.
++ * @ref: reference counter.
++ * @bfqd: parent bfq_data.
++ * @new_ioprio: when an ioprio change is requested, the new ioprio value.
++ * @ioprio_class: the ioprio_class in use.
++ * @new_ioprio_class: when an ioprio_class change is requested, the new
++ *                    ioprio_class value.
++ * @new_bfqq: shared bfq_queue if queue is cooperating with
++ *           one or more other queues.
++ * @sort_list: sorted list of pending requests.
++ * @next_rq: if fifo isn't expired, next request to serve.
++ * @queued: nr of requests queued in @sort_list.
++ * @allocated: currently allocated requests.
++ * @meta_pending: pending metadata requests.
++ * @fifo: fifo list of requests in sort_list.
++ * @entity: entity representing this queue in the scheduler.
++ * @max_budget: maximum budget allowed from the feedback mechanism.
++ * @budget_timeout: budget expiration (in jiffies).
++ * @dispatched: number of requests on the dispatch list or inside driver.
++ * @flags: status flags.
++ * @bfqq_list: node for active/idle bfqq list inside our bfqd.
++ * @burst_list_node: node for the device's burst list.
++ * @seek_samples: number of seeks sampled
++ * @seek_total: sum of the distances of the seeks sampled
++ * @seek_mean: mean seek distance
++ * @last_request_pos: position of the last request enqueued
++ * @requests_within_timer: number of consecutive pairs of request completion
++ *                         and arrival, such that the queue becomes idle
++ *                         after the completion, but the next request arrives
++ *                         within an idle time slice; used only if the queue's
++ *                         IO_bound has been cleared.
++ * @pid: pid of the process owning the queue, used for logging purposes.
++ * @last_wr_start_finish: start time of the current weight-raising period if
++ *                        the @bfq-queue is being weight-raised, otherwise
++ *                        finish time of the last weight-raising period
++ * @wr_cur_max_time: current max raising time for this queue
++ * @soft_rt_next_start: minimum time instant such that, only if a new
++ *                      request is enqueued after this time instant in an
++ *                      idle @bfq_queue with no outstanding requests, then
++ *                      the task associated with the queue it is deemed as
++ *                      soft real-time (see the comments to the function
++ *                      bfq_bfqq_softrt_next_start())
++ * @last_idle_bklogged: time of the last transition of the @bfq_queue from
++ *                      idle to backlogged
++ * @service_from_backlogged: cumulative service received from the @bfq_queue
++ *                           since the last transition from idle to
++ *                           backlogged
++ * @bic: pointer to the bfq_io_cq owning the bfq_queue, set to %NULL if the
++ *	 queue is shared
++ *
++ * A bfq_queue is a leaf request queue; it can be associated with an
++ * io_context or more, if it  is  async or shared  between  cooperating
++ * processes. @cgroup holds a reference to the cgroup, to be sure that it
++ * does not disappear while a bfqq still references it (mostly to avoid
++ * races between request issuing and task migration followed by cgroup
++ * destruction).
++ * All the fields are protected by the queue lock of the containing bfqd.
++ */
++struct bfq_queue {
++	atomic_t ref;
++	struct bfq_data *bfqd;
++
++	unsigned short ioprio, new_ioprio;
++	unsigned short ioprio_class, new_ioprio_class;
++
++	/* fields for cooperating queues handling */
++	struct bfq_queue *new_bfqq;
++	struct rb_node pos_node;
++	struct rb_root *pos_root;
++
++	struct rb_root sort_list;
++	struct request *next_rq;
++	int queued[2];
++	int allocated[2];
++	int meta_pending;
++	struct list_head fifo;
++
++	struct bfq_entity entity;
++
++	int max_budget;
++	unsigned long budget_timeout;
++
++	int dispatched;
++
++	unsigned int flags;
++
++	struct list_head bfqq_list;
++
++	struct hlist_node burst_list_node;
++
++	unsigned int seek_samples;
++	u64 seek_total;
++	sector_t seek_mean;
++	sector_t last_request_pos;
++
++	unsigned int requests_within_timer;
++
++	pid_t pid;
++	struct bfq_io_cq *bic;
++
++	/* weight-raising fields */
++	unsigned long wr_cur_max_time;
++	unsigned long soft_rt_next_start;
++	unsigned long last_wr_start_finish;
++	unsigned int wr_coeff;
++	unsigned long last_idle_bklogged;
++	unsigned long service_from_backlogged;
++};
++
++/**
++ * struct bfq_ttime - per process thinktime stats.
++ * @ttime_total: total process thinktime
++ * @ttime_samples: number of thinktime samples
++ * @ttime_mean: average process thinktime
++ */
++struct bfq_ttime {
++	unsigned long last_end_request;
++
++	unsigned long ttime_total;
++	unsigned long ttime_samples;
++	unsigned long ttime_mean;
++};
++
++/**
++ * struct bfq_io_cq - per (request_queue, io_context) structure.
++ * @icq: associated io_cq structure
++ * @bfqq: array of two process queues, the sync and the async
++ * @ttime: associated @bfq_ttime struct
++ * @ioprio: per (request_queue, blkcg) ioprio.
++ * @blkcg_id: id of the blkcg the related io_cq belongs to.
++ */
++struct bfq_io_cq {
++	struct io_cq icq; /* must be the first member */
++	struct bfq_queue *bfqq[2];
++	struct bfq_ttime ttime;
++	int ioprio;
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	uint64_t blkcg_id; /* the current blkcg ID */
++#endif
++};
++
++enum bfq_device_speed {
++	BFQ_BFQD_FAST,
++	BFQ_BFQD_SLOW,
++};
++
++/**
++ * struct bfq_data - per device data structure.
++ * @queue: request queue for the managed device.
++ * @root_group: root bfq_group for the device.
++ * @active_numerous_groups: number of bfq_groups containing more than one
++ *                          active @bfq_entity.
++ * @queue_weights_tree: rbtree of weight counters of @bfq_queues, sorted by
++ *                      weight. Used to keep track of whether all @bfq_queues
++ *                     have the same weight. The tree contains one counter
++ *                     for each distinct weight associated to some active
++ *                     and not weight-raised @bfq_queue (see the comments to
++ *                      the functions bfq_weights_tree_[add|remove] for
++ *                     further details).
++ * @group_weights_tree: rbtree of non-queue @bfq_entity weight counters, sorted
++ *                      by weight. Used to keep track of whether all
++ *                     @bfq_groups have the same weight. The tree contains
++ *                     one counter for each distinct weight associated to
++ *                     some active @bfq_group (see the comments to the
++ *                     functions bfq_weights_tree_[add|remove] for further
++ *                     details).
++ * @busy_queues: number of bfq_queues containing requests (including the
++ *		 queue in service, even if it is idling).
++ * @busy_in_flight_queues: number of @bfq_queues containing pending or
++ *                         in-flight requests, plus the @bfq_queue in
++ *                         service, even if idle but waiting for the
++ *                         possible arrival of its next sync request. This
++ *                         field is updated only if the device is rotational,
++ *                         but used only if the device is also NCQ-capable.
++ *                         The reason why the field is updated also for non-
++ *                         NCQ-capable rotational devices is related to the
++ *                         fact that the value of @hw_tag may be set also
++ *                         later than when busy_in_flight_queues may need to
++ *                         be incremented for the first time(s). Taking also
++ *                         this possibility into account, to avoid unbalanced
++ *                         increments/decrements, would imply more overhead
++ *                         than just updating busy_in_flight_queues
++ *                         regardless of the value of @hw_tag.
++ * @const_seeky_busy_in_flight_queues: number of constantly-seeky @bfq_queues
++ *                                     (that is, seeky queues that expired
++ *                                     for budget timeout at least once)
++ *                                     containing pending or in-flight
++ *                                     requests, including the in-service
++ *                                     @bfq_queue if constantly seeky. This
++ *                                     field is updated only if the device
++ *                                     is rotational, but used only if the
++ *                                     device is also NCQ-capable (see the
++ *                                     comments to @busy_in_flight_queues).
++ * @wr_busy_queues: number of weight-raised busy @bfq_queues.
++ * @queued: number of queued requests.
++ * @rq_in_driver: number of requests dispatched and waiting for completion.
++ * @sync_flight: number of sync requests in the driver.
++ * @max_rq_in_driver: max number of reqs in driver in the last
++ *                    @hw_tag_samples completed requests.
++ * @hw_tag_samples: nr of samples used to calculate hw_tag.
++ * @hw_tag: flag set to one if the driver is showing a queueing behavior.
++ * @budgets_assigned: number of budgets assigned.
++ * @idle_slice_timer: timer set when idling for the next sequential request
++ *                    from the queue in service.
++ * @unplug_work: delayed work to restart dispatching on the request queue.
++ * @in_service_queue: bfq_queue in service.
++ * @in_service_bic: bfq_io_cq (bic) associated with the @in_service_queue.
++ * @last_position: on-disk position of the last served request.
++ * @last_budget_start: beginning of the last budget.
++ * @last_idling_start: beginning of the last idle slice.
++ * @peak_rate: peak transfer rate observed for a budget.
++ * @peak_rate_samples: number of samples used to calculate @peak_rate.
++ * @bfq_max_budget: maximum budget allotted to a bfq_queue before
++ *                  rescheduling.
++ * @active_list: list of all the bfq_queues active on the device.
++ * @idle_list: list of all the bfq_queues idle on the device.
++ * @bfq_fifo_expire: timeout for async/sync requests; when it expires
++ *                   requests are served in fifo order.
++ * @bfq_back_penalty: weight of backward seeks wrt forward ones.
++ * @bfq_back_max: maximum allowed backward seek.
++ * @bfq_slice_idle: maximum idling time.
++ * @bfq_user_max_budget: user-configured max budget value
++ *                       (0 for auto-tuning).
++ * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to
++ *                           async queues.
++ * @bfq_timeout: timeout for bfq_queues to consume their budget; used to
++ *               to prevent seeky queues to impose long latencies to well
++ *               behaved ones (this also implies that seeky queues cannot
++ *               receive guarantees in the service domain; after a timeout
++ *               they are charged for the whole allocated budget, to try
++ *               to preserve a behavior reasonably fair among them, but
++ *               without service-domain guarantees).
++ * @bfq_coop_thresh: number of queue merges after which a @bfq_queue is
++ *                   no more granted any weight-raising.
++ * @bfq_failed_cooperations: number of consecutive failed cooperation
++ *                           chances after which weight-raising is restored
++ *                           to a queue subject to more than bfq_coop_thresh
++ *                           queue merges.
++ * @bfq_requests_within_timer: number of consecutive requests that must be
++ *                             issued within the idle time slice to set
++ *                             again idling to a queue which was marked as
++ *                             non-I/O-bound (see the definition of the
++ *                             IO_bound flag for further details).
++ * @last_ins_in_burst: last time at which a queue entered the current
++ *                     burst of queues being activated shortly after
++ *                     each other; for more details about this and the
++ *                     following parameters related to a burst of
++ *                     activations, see the comments to the function
++ *                     @bfq_handle_burst.
++ * @bfq_burst_interval: reference time interval used to decide whether a
++ *                      queue has been activated shortly after
++ *                      @last_ins_in_burst.
++ * @burst_size: number of queues in the current burst of queue activations.
++ * @bfq_large_burst_thresh: maximum burst size above which the current
++ * 			    queue-activation burst is deemed as 'large'.
++ * @large_burst: true if a large queue-activation burst is in progress.
++ * @burst_list: head of the burst list (as for the above fields, more details
++ * 		in the comments to the function bfq_handle_burst).
++ * @low_latency: if set to true, low-latency heuristics are enabled.
++ * @bfq_wr_coeff: maximum factor by which the weight of a weight-raised
++ *                queue is multiplied.
++ * @bfq_wr_max_time: maximum duration of a weight-raising period (jiffies).
++ * @bfq_wr_rt_max_time: maximum duration for soft real-time processes.
++ * @bfq_wr_min_idle_time: minimum idle period after which weight-raising
++ *			  may be reactivated for a queue (in jiffies).
++ * @bfq_wr_min_inter_arr_async: minimum period between request arrivals
++ *				after which weight-raising may be
++ *				reactivated for an already busy queue
++ *				(in jiffies).
++ * @bfq_wr_max_softrt_rate: max service-rate for a soft real-time queue,
++ *			    sectors per seconds.
++ * @RT_prod: cached value of the product R*T used for computing the maximum
++ *	     duration of the weight raising automatically.
++ * @device_speed: device-speed class for the low-latency heuristic.
++ * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions.
++ *
++ * All the fields are protected by the @queue lock.
++ */
++struct bfq_data {
++	struct request_queue *queue;
++
++	struct bfq_group *root_group;
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	int active_numerous_groups;
++#endif
++
++	struct rb_root queue_weights_tree;
++	struct rb_root group_weights_tree;
++
++	int busy_queues;
++	int busy_in_flight_queues;
++	int const_seeky_busy_in_flight_queues;
++	int wr_busy_queues;
++	int queued;
++	int rq_in_driver;
++	int sync_flight;
++
++	int max_rq_in_driver;
++	int hw_tag_samples;
++	int hw_tag;
++
++	int budgets_assigned;
++
++	struct timer_list idle_slice_timer;
++	struct work_struct unplug_work;
++
++	struct bfq_queue *in_service_queue;
++	struct bfq_io_cq *in_service_bic;
++
++	sector_t last_position;
++
++	ktime_t last_budget_start;
++	ktime_t last_idling_start;
++	int peak_rate_samples;
++	u64 peak_rate;
++	int bfq_max_budget;
++
++	struct list_head active_list;
++	struct list_head idle_list;
++
++	unsigned int bfq_fifo_expire[2];
++	unsigned int bfq_back_penalty;
++	unsigned int bfq_back_max;
++	unsigned int bfq_slice_idle;
++	u64 bfq_class_idle_last_service;
++
++	int bfq_user_max_budget;
++	int bfq_max_budget_async_rq;
++	unsigned int bfq_timeout[2];
++
++	unsigned int bfq_coop_thresh;
++	unsigned int bfq_failed_cooperations;
++	unsigned int bfq_requests_within_timer;
++
++	unsigned long last_ins_in_burst;
++	unsigned long bfq_burst_interval;
++	int burst_size;
++	unsigned long bfq_large_burst_thresh;
++	bool large_burst;
++	struct hlist_head burst_list;
++
++	bool low_latency;
++
++	/* parameters of the low_latency heuristics */
++	unsigned int bfq_wr_coeff;
++	unsigned int bfq_wr_max_time;
++	unsigned int bfq_wr_rt_max_time;
++	unsigned int bfq_wr_min_idle_time;
++	unsigned long bfq_wr_min_inter_arr_async;
++	unsigned int bfq_wr_max_softrt_rate;
++	u64 RT_prod;
++	enum bfq_device_speed device_speed;
++
++	struct bfq_queue oom_bfqq;
++};
++
++enum bfqq_state_flags {
++	BFQ_BFQQ_FLAG_busy = 0,		/* has requests or is in service */
++	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
++	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
++	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
++	BFQ_BFQQ_FLAG_idle_window,	/* slice idling enabled */
++	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
++	BFQ_BFQQ_FLAG_budget_new,	/* no completion with this budget */
++	BFQ_BFQQ_FLAG_IO_bound,		/*
++					 * bfqq has timed-out at least once
++					 * having consumed at most 2/10 of
++					 * its budget
++					 */
++	BFQ_BFQQ_FLAG_in_large_burst,	/*
++					 * bfqq activated in a large burst,
++					 * see comments to bfq_handle_burst.
++					 */
++	BFQ_BFQQ_FLAG_constantly_seeky,	/*
++					 * bfqq has proved to be slow and
++					 * seeky until budget timeout
++					 */
++	BFQ_BFQQ_FLAG_softrt_update,	/*
++					 * may need softrt-next-start
++					 * update
++					 */
++};
++
++#define BFQ_BFQQ_FNS(name)						\
++static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)		\
++{									\
++	(bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name);			\
++}									\
++static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq)		\
++{									\
++	(bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name);			\
++}									\
++static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
++{									\
++	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
++}
++
++BFQ_BFQQ_FNS(busy);
++BFQ_BFQQ_FNS(wait_request);
++BFQ_BFQQ_FNS(must_alloc);
++BFQ_BFQQ_FNS(fifo_expire);
++BFQ_BFQQ_FNS(idle_window);
++BFQ_BFQQ_FNS(sync);
++BFQ_BFQQ_FNS(budget_new);
++BFQ_BFQQ_FNS(IO_bound);
++BFQ_BFQQ_FNS(in_large_burst);
++BFQ_BFQQ_FNS(constantly_seeky);
++BFQ_BFQQ_FNS(softrt_update);
++#undef BFQ_BFQQ_FNS
++
++/* Logging facilities. */
++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
++	blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args)
++
++#define bfq_log(bfqd, fmt, args...) \
++	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
++
++/* Expiration reasons. */
++enum bfqq_expiration {
++	BFQ_BFQQ_TOO_IDLE = 0,		/*
++					 * queue has been idling for
++					 * too long
++					 */
++	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
++	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
++	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
++};
++
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++
++struct bfqg_stats {
++	/* total bytes transferred */
++	struct blkg_rwstat		service_bytes;
++	/* total IOs serviced, post merge */
++	struct blkg_rwstat		serviced;
++	/* number of ios merged */
++	struct blkg_rwstat		merged;
++	/* total time spent on device in ns, may not be accurate w/ queueing */
++	struct blkg_rwstat		service_time;
++	/* total time spent waiting in scheduler queue in ns */
++	struct blkg_rwstat		wait_time;
++	/* number of IOs queued up */
++	struct blkg_rwstat		queued;
++	/* total sectors transferred */
++	struct blkg_stat		sectors;
++	/* total disk time and nr sectors dispatched by this group */
++	struct blkg_stat		time;
++	/* time not charged to this cgroup */
++	struct blkg_stat		unaccounted_time;
++	/* sum of number of ios queued across all samples */
++	struct blkg_stat		avg_queue_size_sum;
++	/* count of samples taken for average */
++	struct blkg_stat		avg_queue_size_samples;
++	/* how many times this group has been removed from service tree */
++	struct blkg_stat		dequeue;
++	/* total time spent waiting for it to be assigned a timeslice. */
++	struct blkg_stat		group_wait_time;
++	/* time spent idling for this blkcg_gq */
++	struct blkg_stat		idle_time;
++	/* total time with empty current active q with other requests queued */
++	struct blkg_stat		empty_time;
++	/* fields after this shouldn't be cleared on stat reset */
++	uint64_t			start_group_wait_time;
++	uint64_t			start_idle_time;
++	uint64_t			start_empty_time;
++	uint16_t			flags;
++};
++
++/*
++ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
++ *
++ * @ps: @blkcg_policy_storage that this structure inherits
++ * @weight: weight of the bfq_group
++ */
++struct bfq_group_data {
++	/* must be the first member */
++	struct blkcg_policy_data pd;
++
++	unsigned short weight;
++};
++
++/**
++ * struct bfq_group - per (device, cgroup) data structure.
++ * @entity: schedulable entity to insert into the parent group sched_data.
++ * @sched_data: own sched_data, to contain child entities (they may be
++ *              both bfq_queues and bfq_groups).
++ * @bfqd: the bfq_data for the device this group acts upon.
++ * @async_bfqq: array of async queues for all the tasks belonging to
++ *              the group, one queue per ioprio value per ioprio_class,
++ *              except for the idle class that has only one queue.
++ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
++ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
++ *             to avoid too many special cases during group creation/
++ *             migration.
++ * @active_entities: number of active entities belonging to the group;
++ *                   unused for the root group. Used to know whether there
++ *                   are groups with more than one active @bfq_entity
++ *                   (see the comments to the function
++ *                   bfq_bfqq_must_not_expire()).
++ *
++ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
++ * there is a set of bfq_groups, each one collecting the lower-level
++ * entities belonging to the group that are acting on the same device.
++ *
++ * Locking works as follows:
++ *    o @bfqd is protected by the queue lock, RCU is used to access it
++ *      from the readers.
++ *    o All the other fields are protected by the @bfqd queue lock.
++ */
++struct bfq_group {
++	/* must be the first member */
++	struct blkg_policy_data pd;
++
++	struct bfq_entity entity;
++	struct bfq_sched_data sched_data;
++
++	void *bfqd;
++
++	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
++	struct bfq_queue *async_idle_bfqq;
++
++	struct bfq_entity *my_entity;
++
++	int active_entities;
++
++	struct bfqg_stats stats;
++	struct bfqg_stats dead_stats;	/* stats pushed from dead children */
++};
++
++#else
++struct bfq_group {
++	struct bfq_sched_data sched_data;
++
++	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
++	struct bfq_queue *async_idle_bfqq;
++};
++#endif
++
++static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
++
++static struct bfq_service_tree *
++bfq_entity_service_tree(struct bfq_entity *entity)
++{
++	struct bfq_sched_data *sched_data = entity->sched_data;
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	unsigned int idx = bfqq ? bfqq->ioprio_class - 1 :
++				  BFQ_DEFAULT_GRP_CLASS;
++
++	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
++	BUG_ON(sched_data == NULL);
++
++	return sched_data->service_tree + idx;
++}
++
++static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
++{
++	return bic->bfqq[is_sync];
++}
++
++static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
++			 bool is_sync)
++{
++	bic->bfqq[is_sync] = bfqq;
++}
++
++static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
++{
++	return bic->icq.q->elevator->elevator_data;
++}
++
++/**
++ * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer.
++ * @ptr: a pointer to a bfqd.
++ * @flags: storage for the flags to be saved.
++ *
++ * This function allows bfqg->bfqd to be protected by the
++ * queue lock of the bfqd they reference; the pointer is dereferenced
++ * under RCU, so the storage for bfqd is assured to be safe as long
++ * as the RCU read side critical section does not end.  After the
++ * bfqd->queue->queue_lock is taken the pointer is rechecked, to be
++ * sure that no other writer accessed it.  If we raced with a writer,
++ * the function returns NULL, with the queue unlocked, otherwise it
++ * returns the dereferenced pointer, with the queue locked.
++ */
++static struct bfq_data *bfq_get_bfqd_locked(void **ptr, unsigned long *flags)
++{
++	struct bfq_data *bfqd;
++
++	rcu_read_lock();
++	bfqd = rcu_dereference(*(struct bfq_data **)ptr);
++
++	if (bfqd != NULL) {
++		spin_lock_irqsave(bfqd->queue->queue_lock, *flags);
++		if (ptr == NULL)
++			printk(KERN_CRIT "get_bfqd_locked pointer NULL\n");
++		else if (*ptr == bfqd)
++			goto out;
++		spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
++	}
++
++	bfqd = NULL;
++out:
++	rcu_read_unlock();
++	return bfqd;
++}
++
++static void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags)
++{
++	spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
++}
++
++static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
++static void bfq_put_queue(struct bfq_queue *bfqq);
++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
++				       struct bio *bio, int is_sync,
++				       struct bfq_io_cq *bic, gfp_t gfp_mask);
++static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
++				    struct bfq_group *bfqg);
++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
++
++#endif /* _BFQ_H */
+-- 
+1.9.1
+
diff --git a/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.7.patch b/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.7.patch
new file mode 100644
index 00000000..eb23acc5
--- /dev/null
+++ b/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r11-for-4.7.patch
@@ -0,0 +1,1101 @@
+From d93e55da4df8c5e7c33379780ad7d2fdb02e0568 Mon Sep 17 00:00:00 2001
+From: Mauro Andreolini <mauro.andreolini@unimore.it>
+Date: Sun, 6 Sep 2015 16:09:05 +0200
+Subject: [PATCH 3/4] block, bfq: add Early Queue Merge (EQM) to BFQ-v7r11 for
+ 4.7.0
+
+A set of processes may happen  to  perform interleaved reads, i.e.,requests
+whose union would give rise to a  sequential read  pattern.  There are two
+typical  cases: in the first  case,   processes  read  fixed-size chunks of
+data at a fixed distance from each other, while in the second case processes
+may read variable-size chunks at  variable distances. The latter case occurs
+for  example with  QEMU, which  splits the  I/O generated  by the  guest into
+multiple chunks,  and lets these chunks  be served by a  pool of cooperating
+processes,  iteratively  assigning  the  next  chunk of  I/O  to  the first
+available  process. CFQ  uses actual  queue merging  for the  first type of
+rocesses, whereas it  uses preemption to get a sequential  read pattern out
+of the read requests  performed by the second type of  processes. In the end
+it uses  two different  mechanisms to  achieve the  same goal: boosting the
+throughput with interleaved I/O.
+
+This patch introduces  Early Queue Merge (EQM), a unified mechanism to get a
+sequential  read pattern  with both  types of  processes. The  main idea is
+checking newly arrived requests against the next request of the active queue
+both in case of actual request insert and in case of request merge. By doing
+so, both the types of processes can be handled by just merging their queues.
+EQM is  then simpler and  more compact than the  pair of mechanisms used in
+CFQ.
+
+Finally, EQM  also preserves the  typical low-latency properties of BFQ, by
+properly restoring the weight-raising state of a queue when it gets back to
+a non-merged state.
+
+Signed-off-by: Mauro Andreolini <mauro.andreolini@unimore.it>
+Signed-off-by: Arianna Avanzini <avanzini@google.com>
+Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
+Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
+---
+ block/bfq-cgroup.c  |   4 +
+ block/bfq-iosched.c | 687 ++++++++++++++++++++++++++++++++++++++++++++++++++--
+ block/bfq.h         |  66 +++++
+ 3 files changed, 743 insertions(+), 14 deletions(-)
+
+diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
+index 8610cd6..5ee99ec 100644
+--- a/block/bfq-cgroup.c
++++ b/block/bfq-cgroup.c
+@@ -437,6 +437,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
+ 				   */
+ 	bfqg->bfqd = bfqd;
+ 	bfqg->active_entities = 0;
++	bfqg->rq_pos_tree = RB_ROOT;
+ }
+ 
+ static void bfq_pd_free(struct blkg_policy_data *pd)
+@@ -530,6 +531,8 @@ static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+ 	return bfqg;
+ }
+ 
++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
++
+ /**
+  * bfq_bfqq_move - migrate @bfqq to @bfqg.
+  * @bfqd: queue descriptor.
+@@ -577,6 +580,7 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	bfqg_get(bfqg);
+ 
+ 	if (busy) {
++		bfq_pos_tree_add_move(bfqd, bfqq);
+ 		if (resume)
+ 			bfq_activate_bfqq(bfqd, bfqq);
+ 	}
+diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
+index f9787a6..d1f648d 100644
+--- a/block/bfq-iosched.c
++++ b/block/bfq-iosched.c
+@@ -296,6 +296,72 @@ static struct request *bfq_choose_req(struct bfq_data *bfqd,
+ 	}
+ }
+ 
++static struct bfq_queue *
++bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
++		     sector_t sector, struct rb_node **ret_parent,
++		     struct rb_node ***rb_link)
++{
++	struct rb_node **p, *parent;
++	struct bfq_queue *bfqq = NULL;
++
++	parent = NULL;
++	p = &root->rb_node;
++	while (*p) {
++		struct rb_node **n;
++
++		parent = *p;
++		bfqq = rb_entry(parent, struct bfq_queue, pos_node);
++
++		/*
++		 * Sort strictly based on sector. Smallest to the left,
++		 * largest to the right.
++		 */
++		if (sector > blk_rq_pos(bfqq->next_rq))
++			n = &(*p)->rb_right;
++		else if (sector < blk_rq_pos(bfqq->next_rq))
++			n = &(*p)->rb_left;
++		else
++			break;
++		p = n;
++		bfqq = NULL;
++	}
++
++	*ret_parent = parent;
++	if (rb_link)
++		*rb_link = p;
++
++	bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
++		(long long unsigned)sector,
++		bfqq ? bfqq->pid : 0);
++
++	return bfqq;
++}
++
++static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
++{
++	struct rb_node **p, *parent;
++	struct bfq_queue *__bfqq;
++
++	if (bfqq->pos_root) {
++		rb_erase(&bfqq->pos_node, bfqq->pos_root);
++		bfqq->pos_root = NULL;
++	}
++
++	if (bfq_class_idle(bfqq))
++		return;
++	if (!bfqq->next_rq)
++		return;
++
++	bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
++	__bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
++			blk_rq_pos(bfqq->next_rq), &parent, &p);
++	if (!__bfqq) {
++		rb_link_node(&bfqq->pos_node, parent, p);
++		rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
++	} else
++		bfqq->pos_root = NULL;
++}
++
+ /*
+  * Tell whether there are active queues or groups with differentiated weights.
+  */
+@@ -528,6 +594,57 @@ static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
+ 	return dur;
+ }
+ 
++static unsigned bfq_bfqq_cooperations(struct bfq_queue *bfqq)
++{
++	return bfqq->bic ? bfqq->bic->cooperations : 0;
++}
++
++static void
++bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
++{
++	if (bic->saved_idle_window)
++		bfq_mark_bfqq_idle_window(bfqq);
++	else
++		bfq_clear_bfqq_idle_window(bfqq);
++	if (bic->saved_IO_bound)
++		bfq_mark_bfqq_IO_bound(bfqq);
++	else
++		bfq_clear_bfqq_IO_bound(bfqq);
++	/* Assuming that the flag in_large_burst is already correctly set */
++	if (bic->wr_time_left && bfqq->bfqd->low_latency &&
++	    !bfq_bfqq_in_large_burst(bfqq) &&
++	    bic->cooperations < bfqq->bfqd->bfq_coop_thresh) {
++		/*
++		 * Start a weight raising period with the duration given by
++		 * the raising_time_left snapshot.
++		 */
++		if (bfq_bfqq_busy(bfqq))
++			bfqq->bfqd->wr_busy_queues++;
++		bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff;
++		bfqq->wr_cur_max_time = bic->wr_time_left;
++		bfqq->last_wr_start_finish = jiffies;
++		bfqq->entity.prio_changed = 1;
++	}
++	/*
++	 * Clear wr_time_left to prevent bfq_bfqq_save_state() from
++	 * getting confused about the queue's need of a weight-raising
++	 * period.
++	 */
++	bic->wr_time_left = 0;
++}
++
++static int bfqq_process_refs(struct bfq_queue *bfqq)
++{
++	int process_refs, io_refs;
++
++	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
++
++	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
++	process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st;
++	BUG_ON(process_refs < 0);
++	return process_refs;
++}
++
+ /* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
+ static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ {
+@@ -764,8 +881,14 @@ static void bfq_add_request(struct request *rq)
+ 	BUG_ON(!next_rq);
+ 	bfqq->next_rq = next_rq;
+ 
++	/*
++	 * Adjust priority tree position, if next_rq changes.
++	 */
++	if (prev != bfqq->next_rq)
++		bfq_pos_tree_add_move(bfqd, bfqq);
++
+ 	if (!bfq_bfqq_busy(bfqq)) {
+-		bool soft_rt, in_burst,
++		bool soft_rt, coop_or_in_burst,
+ 		     idle_for_long_time = time_is_before_jiffies(
+ 						bfqq->budget_timeout +
+ 						bfqd->bfq_wr_min_idle_time);
+@@ -793,11 +916,12 @@ static void bfq_add_request(struct request *rq)
+ 				bfqd->last_ins_in_burst = jiffies;
+ 		}
+ 
+-		in_burst = bfq_bfqq_in_large_burst(bfqq);
++		coop_or_in_burst = bfq_bfqq_in_large_burst(bfqq) ||
++			bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh;
+ 		soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
+-			!in_burst &&
++			!coop_or_in_burst &&
+ 			time_is_before_jiffies(bfqq->soft_rt_next_start);
+-		interactive = !in_burst && idle_for_long_time;
++		interactive = !coop_or_in_burst && idle_for_long_time;
+ 		entity->budget = max_t(unsigned long, bfqq->max_budget,
+ 				       bfq_serv_to_charge(next_rq, bfqq));
+ 
+@@ -816,6 +940,9 @@ static void bfq_add_request(struct request *rq)
+ 		if (!bfqd->low_latency)
+ 			goto add_bfqq_busy;
+ 
++		if (bfq_bfqq_just_split(bfqq))
++			goto set_prio_changed;
++
+ 		/*
+ 		 * If the queue:
+ 		 * - is not being boosted,
+@@ -840,7 +967,7 @@ static void bfq_add_request(struct request *rq)
+ 		} else if (old_wr_coeff > 1) {
+ 			if (interactive)
+ 				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+-			else if (in_burst ||
++			else if (coop_or_in_burst ||
+ 				 (bfqq->wr_cur_max_time ==
+ 				  bfqd->bfq_wr_rt_max_time &&
+ 				  !soft_rt)) {
+@@ -905,6 +1032,7 @@ static void bfq_add_request(struct request *rq)
+ 					bfqd->bfq_wr_rt_max_time;
+ 			}
+ 		}
++set_prio_changed:
+ 		if (old_wr_coeff != bfqq->wr_coeff)
+ 			entity->prio_changed = 1;
+ add_bfqq_busy:
+@@ -1047,6 +1175,15 @@ static void bfq_merged_request(struct request_queue *q, struct request *req,
+ 					 bfqd->last_position);
+ 		BUG_ON(!next_rq);
+ 		bfqq->next_rq = next_rq;
++		/*
++		 * If next_rq changes, update both the queue's budget to
++		 * fit the new request and the queue's position in its
++		 * rq_pos_tree.
++		 */
++		if (prev != bfqq->next_rq) {
++			bfq_updated_next_req(bfqd, bfqq);
++			bfq_pos_tree_add_move(bfqd, bfqq);
++		}
+ 	}
+ }
+ 
+@@ -1129,11 +1266,346 @@ static void bfq_end_wr(struct bfq_data *bfqd)
+ 	spin_unlock_irq(bfqd->queue->queue_lock);
+ }
+ 
++static sector_t bfq_io_struct_pos(void *io_struct, bool request)
++{
++	if (request)
++		return blk_rq_pos(io_struct);
++	else
++		return ((struct bio *)io_struct)->bi_iter.bi_sector;
++}
++
++static int bfq_rq_close_to_sector(void *io_struct, bool request,
++				  sector_t sector)
++{
++	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
++	       BFQQ_SEEK_THR;
++}
++
++static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
++					 struct bfq_queue *bfqq,
++					 sector_t sector)
++{
++	struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
++	struct rb_node *parent, *node;
++	struct bfq_queue *__bfqq;
++
++	if (RB_EMPTY_ROOT(root))
++		return NULL;
++
++	/*
++	 * First, if we find a request starting at the end of the last
++	 * request, choose it.
++	 */
++	__bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
++	if (__bfqq)
++		return __bfqq;
++
++	/*
++	 * If the exact sector wasn't found, the parent of the NULL leaf
++	 * will contain the closest sector (rq_pos_tree sorted by
++	 * next_request position).
++	 */
++	__bfqq = rb_entry(parent, struct bfq_queue, pos_node);
++	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
++		return __bfqq;
++
++	if (blk_rq_pos(__bfqq->next_rq) < sector)
++		node = rb_next(&__bfqq->pos_node);
++	else
++		node = rb_prev(&__bfqq->pos_node);
++	if (!node)
++		return NULL;
++
++	__bfqq = rb_entry(node, struct bfq_queue, pos_node);
++	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
++		return __bfqq;
++
++	return NULL;
++}
++
++static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
++						   struct bfq_queue *cur_bfqq,
++						   sector_t sector)
++{
++	struct bfq_queue *bfqq;
++
++	/*
++	 * We shall notice if some of the queues are cooperating,
++	 * e.g., working closely on the same area of the device. In
++	 * that case, we can group them together and: 1) don't waste
++	 * time idling, and 2) serve the union of their requests in
++	 * the best possible order for throughput.
++	 */
++	bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
++	if (!bfqq || bfqq == cur_bfqq)
++		return NULL;
++
++	return bfqq;
++}
++
++static struct bfq_queue *
++bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
++{
++	int process_refs, new_process_refs;
++	struct bfq_queue *__bfqq;
++
++	/*
++	 * If there are no process references on the new_bfqq, then it is
++	 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
++	 * may have dropped their last reference (not just their last process
++	 * reference).
++	 */
++	if (!bfqq_process_refs(new_bfqq))
++		return NULL;
++
++	/* Avoid a circular list and skip interim queue merges. */
++	while ((__bfqq = new_bfqq->new_bfqq)) {
++		if (__bfqq == bfqq)
++			return NULL;
++		new_bfqq = __bfqq;
++	}
++
++	process_refs = bfqq_process_refs(bfqq);
++	new_process_refs = bfqq_process_refs(new_bfqq);
++	/*
++	 * If the process for the bfqq has gone away, there is no
++	 * sense in merging the queues.
++	 */
++	if (process_refs == 0 || new_process_refs == 0)
++		return NULL;
++
++	bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
++		new_bfqq->pid);
++
++	/*
++	 * Merging is just a redirection: the requests of the process
++	 * owning one of the two queues are redirected to the other queue.
++	 * The latter queue, in its turn, is set as shared if this is the
++	 * first time that the requests of some process are redirected to
++	 * it.
++	 *
++	 * We redirect bfqq to new_bfqq and not the opposite, because we
++	 * are in the context of the process owning bfqq, hence we have
++	 * the io_cq of this process. So we can immediately configure this
++	 * io_cq to redirect the requests of the process to new_bfqq.
++	 *
++	 * NOTE, even if new_bfqq coincides with the in-service queue, the
++	 * io_cq of new_bfqq is not available, because, if the in-service
++	 * queue is shared, bfqd->in_service_bic may not point to the
++	 * io_cq of the in-service queue.
++	 * Redirecting the requests of the process owning bfqq to the
++	 * currently in-service queue is in any case the best option, as
++	 * we feed the in-service queue with new requests close to the
++	 * last request served and, by doing so, hopefully increase the
++	 * throughput.
++	 */
++	bfqq->new_bfqq = new_bfqq;
++	atomic_add(process_refs, &new_bfqq->ref);
++	return new_bfqq;
++}
++
++static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
++					struct bfq_queue *new_bfqq)
++{
++	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
++	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
++		return false;
++
++	/*
++	 * If either of the queues has already been detected as seeky,
++	 * then merging it with the other queue is unlikely to lead to
++	 * sequential I/O.
++	 */
++	if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
++		return false;
++
++	/*
++	 * Interleaved I/O is known to be done by (some) applications
++	 * only for reads, so it does not make sense to merge async
++	 * queues.
++	 */
++	if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
++		return false;
++
++	return true;
++}
++
++/*
++ * Attempt to schedule a merge of bfqq with the currently in-service queue
++ * or with a close queue among the scheduled queues.
++ * Return NULL if no merge was scheduled, a pointer to the shared bfq_queue
++ * structure otherwise.
++ *
++ * The OOM queue is not allowed to participate to cooperation: in fact, since
++ * the requests temporarily redirected to the OOM queue could be redirected
++ * again to dedicated queues at any time, the state needed to correctly
++ * handle merging with the OOM queue would be quite complex and expensive
++ * to maintain. Besides, in such a critical condition as an out of memory,
++ * the benefits of queue merging may be little relevant, or even negligible.
++ */
++static struct bfq_queue *
++bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++		     void *io_struct, bool request)
++{
++	struct bfq_queue *in_service_bfqq, *new_bfqq;
++
++	if (bfqq->new_bfqq)
++		return bfqq->new_bfqq;
++	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
++		return NULL;
++	/* If device has only one backlogged bfq_queue, don't search. */
++	if (bfqd->busy_queues == 1)
++		return NULL;
++
++	in_service_bfqq = bfqd->in_service_queue;
++
++	if (!in_service_bfqq || in_service_bfqq == bfqq ||
++	    !bfqd->in_service_bic ||
++	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
++		goto check_scheduled;
++
++	if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
++	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
++	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
++		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
++		if (new_bfqq)
++			return new_bfqq;
++	}
++	/*
++	 * Check whether there is a cooperator among currently scheduled
++	 * queues. The only thing we need is that the bio/request is not
++	 * NULL, as we need it to establish whether a cooperator exists.
++	 */
++check_scheduled:
++	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
++			bfq_io_struct_pos(io_struct, request));
++
++	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
++
++	if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) &&
++	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
++		return bfq_setup_merge(bfqq, new_bfqq);
++
++	return NULL;
++}
++
++static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
++{
++	/*
++	 * If !bfqq->bic, the queue is already shared or its requests
++	 * have already been redirected to a shared queue; both idle window
++	 * and weight raising state have already been saved. Do nothing.
++	 */
++	if (!bfqq->bic)
++		return;
++	if (bfqq->bic->wr_time_left)
++		/*
++		 * This is the queue of a just-started process, and would
++		 * deserve weight raising: we set wr_time_left to the full
++		 * weight-raising duration to trigger weight-raising when
++		 * and if the queue is split and the first request of the
++		 * queue is enqueued.
++		 */
++		bfqq->bic->wr_time_left = bfq_wr_duration(bfqq->bfqd);
++	else if (bfqq->wr_coeff > 1) {
++		unsigned long wr_duration =
++			jiffies - bfqq->last_wr_start_finish;
++		/*
++		 * It may happen that a queue's weight raising period lasts
++		 * longer than its wr_cur_max_time, as weight raising is
++		 * handled only when a request is enqueued or dispatched (it
++		 * does not use any timer). If the weight raising period is
++		 * about to end, don't save it.
++		 */
++		if (bfqq->wr_cur_max_time <= wr_duration)
++			bfqq->bic->wr_time_left = 0;
++		else
++			bfqq->bic->wr_time_left =
++				bfqq->wr_cur_max_time - wr_duration;
++		/*
++		 * The bfq_queue is becoming shared or the requests of the
++		 * process owning the queue are being redirected to a shared
++		 * queue. Stop the weight raising period of the queue, as in
++		 * both cases it should not be owned by an interactive or
++		 * soft real-time application.
++		 */
++		bfq_bfqq_end_wr(bfqq);
++	} else
++		bfqq->bic->wr_time_left = 0;
++	bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
++	bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
++	bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
++	bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
++	bfqq->bic->cooperations++;
++	bfqq->bic->failed_cooperations = 0;
++}
++
++static void bfq_get_bic_reference(struct bfq_queue *bfqq)
++{
++	/*
++	 * If bfqq->bic has a non-NULL value, the bic to which it belongs
++	 * is about to begin using a shared bfq_queue.
++	 */
++	if (bfqq->bic)
++		atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
++}
++
++static void
++bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
++		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
++{
++	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
++		(long unsigned)new_bfqq->pid);
++	/* Save weight raising and idle window of the merged queues */
++	bfq_bfqq_save_state(bfqq);
++	bfq_bfqq_save_state(new_bfqq);
++	if (bfq_bfqq_IO_bound(bfqq))
++		bfq_mark_bfqq_IO_bound(new_bfqq);
++	bfq_clear_bfqq_IO_bound(bfqq);
++	/*
++	 * Grab a reference to the bic, to prevent it from being destroyed
++	 * before being possibly touched by a bfq_split_bfqq().
++	 */
++	bfq_get_bic_reference(bfqq);
++	bfq_get_bic_reference(new_bfqq);
++	/*
++	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
++	 */
++	bic_set_bfqq(bic, new_bfqq, 1);
++	bfq_mark_bfqq_coop(new_bfqq);
++	/*
++	 * new_bfqq now belongs to at least two bics (it is a shared queue):
++	 * set new_bfqq->bic to NULL. bfqq either:
++	 * - does not belong to any bic any more, and hence bfqq->bic must
++	 *   be set to NULL, or
++	 * - is a queue whose owning bics have already been redirected to a
++	 *   different queue, hence the queue is destined to not belong to
++	 *   any bic soon and bfqq->bic is already NULL (therefore the next
++	 *   assignment causes no harm).
++	 */
++	new_bfqq->bic = NULL;
++	bfqq->bic = NULL;
++	bfq_put_queue(bfqq);
++}
++
++static void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq)
++{
++	struct bfq_io_cq *bic = bfqq->bic;
++	struct bfq_data *bfqd = bfqq->bfqd;
++
++	if (bic && bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh) {
++		bic->failed_cooperations++;
++		if (bic->failed_cooperations >= bfqd->bfq_failed_cooperations)
++			bic->cooperations = 0;
++	}
++}
++
+ static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ 			   struct bio *bio)
+ {
+ 	struct bfq_data *bfqd = q->elevator->elevator_data;
+ 	struct bfq_io_cq *bic;
++	struct bfq_queue *bfqq, *new_bfqq;
+ 
+ 	/*
+ 	 * Disallow merge of a sync bio into an async request.
+@@ -1150,7 +1622,26 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ 	if (!bic)
+ 		return 0;
+ 
+-	return bic_to_bfqq(bic, bfq_bio_sync(bio)) == RQ_BFQQ(rq);
++	bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio));
++	/*
++	 * We take advantage of this function to perform an early merge
++	 * of the queues of possible cooperating processes.
++	 */
++	if (bfqq) {
++		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
++		if (new_bfqq) {
++			bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
++			/*
++			 * If we get here, the bio will be queued in the
++			 * shared queue, i.e., new_bfqq, so use new_bfqq
++			 * to decide whether bio and rq can be merged.
++			 */
++			bfqq = new_bfqq;
++		} else
++			bfq_bfqq_increase_failed_cooperations(bfqq);
++	}
++
++	return bfqq == RQ_BFQQ(rq);
+ }
+ 
+ static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
+@@ -1349,6 +1840,15 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 
+ 	__bfq_bfqd_reset_in_service(bfqd);
+ 
++	/*
++	 * If this bfqq is shared between multiple processes, check
++	 * to make sure that those processes are still issuing I/Os
++	 * within the mean seek distance. If not, it may be time to
++	 * break the queues apart again.
++	 */
++	if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
++		bfq_mark_bfqq_split_coop(bfqq);
++
+ 	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ 		/*
+ 		 * Overloading budget_timeout field to store the time
+@@ -1357,8 +1857,13 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		 */
+ 		bfqq->budget_timeout = jiffies;
+ 		bfq_del_bfqq_busy(bfqd, bfqq, 1);
+-	} else
++	} else {
+ 		bfq_activate_bfqq(bfqd, bfqq);
++		/*
++		 * Resort priority tree of potential close cooperators.
++		 */
++		bfq_pos_tree_add_move(bfqd, bfqq);
++	}
+ }
+ 
+ /**
+@@ -2242,10 +2747,12 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		/*
+ 		 * If the queue was activated in a burst, or
+ 		 * too much time has elapsed from the beginning
+-		 * of this weight-raising period, then end weight
+-		 * raising.
++		 * of this weight-raising period, or the queue has
++		 * exceeded the acceptable number of cooperations,
++		 * then end weight raising.
+ 		 */
+ 		if (bfq_bfqq_in_large_burst(bfqq) ||
++		    bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh ||
+ 		    time_is_before_jiffies(bfqq->last_wr_start_finish +
+ 					   bfqq->wr_cur_max_time)) {
+ 			bfqq->last_wr_start_finish = jiffies;
+@@ -2474,6 +2981,25 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
+ #endif
+ }
+ 
++static void bfq_put_cooperator(struct bfq_queue *bfqq)
++{
++	struct bfq_queue *__bfqq, *next;
++
++	/*
++	 * If this queue was scheduled to merge with another queue, be
++	 * sure to drop the reference taken on that queue (and others in
++	 * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
++	 */
++	__bfqq = bfqq->new_bfqq;
++	while (__bfqq) {
++		if (__bfqq == bfqq)
++			break;
++		next = __bfqq->new_bfqq;
++		bfq_put_queue(__bfqq);
++		__bfqq = next;
++	}
++}
++
+ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ {
+ 	if (bfqq == bfqd->in_service_queue) {
+@@ -2484,6 +3010,8 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq,
+ 		     atomic_read(&bfqq->ref));
+ 
++	bfq_put_cooperator(bfqq);
++
+ 	bfq_put_queue(bfqq);
+ }
+ 
+@@ -2492,6 +3020,25 @@ static void bfq_init_icq(struct io_cq *icq)
+ 	struct bfq_io_cq *bic = icq_to_bic(icq);
+ 
+ 	bic->ttime.last_end_request = jiffies;
++	/*
++	 * A newly created bic indicates that the process has just
++	 * started doing I/O, and is probably mapping into memory its
++	 * executable and libraries: it definitely needs weight raising.
++	 * There is however the possibility that the process performs,
++	 * for a while, I/O close to some other process. EQM intercepts
++	 * this behavior and may merge the queue corresponding to the
++	 * process  with some other queue, BEFORE the weight of the queue
++	 * is raised. Merged queues are not weight-raised (they are assumed
++	 * to belong to processes that benefit only from high throughput).
++	 * If the merge is basically the consequence of an accident, then
++	 * the queue will be split soon and will get back its old weight.
++	 * It is then important to write down somewhere that this queue
++	 * does need weight raising, even if it did not make it to get its
++	 * weight raised before being merged. To this purpose, we overload
++	 * the field raising_time_left and assign 1 to it, to mark the queue
++	 * as needing weight raising.
++	 */
++	bic->wr_time_left = 1;
+ }
+ 
+ static void bfq_exit_icq(struct io_cq *icq)
+@@ -2505,6 +3052,13 @@ static void bfq_exit_icq(struct io_cq *icq)
+ 	}
+ 
+ 	if (bic->bfqq[BLK_RW_SYNC]) {
++		/*
++		 * If the bic is using a shared queue, put the reference
++		 * taken on the io_context when the bic started using a
++		 * shared bfq_queue.
++		 */
++		if (bfq_bfqq_coop(bic->bfqq[BLK_RW_SYNC]))
++			put_io_context(icq->ioc);
+ 		bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]);
+ 		bic->bfqq[BLK_RW_SYNC] = NULL;
+ 	}
+@@ -2809,6 +3363,10 @@ static void bfq_update_idle_window(struct bfq_data *bfqd,
+ 	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
+ 		return;
+ 
++	/* Idle window just restored, statistics are meaningless. */
++	if (bfq_bfqq_just_split(bfqq))
++		return;
++
+ 	enable_idle = bfq_bfqq_idle_window(bfqq);
+ 
+ 	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
+@@ -2856,6 +3414,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ 	    !BFQQ_SEEKY(bfqq))
+ 		bfq_update_idle_window(bfqd, bfqq, bic);
++	bfq_clear_bfqq_just_split(bfqq);
+ 
+ 	bfq_log_bfqq(bfqd, bfqq,
+ 		     "rq_enqueued: idle_window=%d (seeky %d, mean %llu)",
+@@ -2920,12 +3479,47 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ static void bfq_insert_request(struct request_queue *q, struct request *rq)
+ {
+ 	struct bfq_data *bfqd = q->elevator->elevator_data;
+-	struct bfq_queue *bfqq = RQ_BFQQ(rq);
++	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
+ 
+ 	assert_spin_locked(bfqd->queue->queue_lock);
+ 
++	/*
++	 * An unplug may trigger a requeue of a request from the device
++	 * driver: make sure we are in process context while trying to
++	 * merge two bfq_queues.
++	 */
++	if (!in_interrupt()) {
++		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
++		if (new_bfqq) {
++			if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
++				new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
++			/*
++			 * Release the request's reference to the old bfqq
++			 * and make sure one is taken to the shared queue.
++			 */
++			new_bfqq->allocated[rq_data_dir(rq)]++;
++			bfqq->allocated[rq_data_dir(rq)]--;
++			atomic_inc(&new_bfqq->ref);
++			bfq_put_queue(bfqq);
++			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
++				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
++						bfqq, new_bfqq);
++			rq->elv.priv[1] = new_bfqq;
++			bfqq = new_bfqq;
++		} else
++			bfq_bfqq_increase_failed_cooperations(bfqq);
++	}
++
+ 	bfq_add_request(rq);
+ 
++	/*
++	 * Here a newly-created bfq_queue has already started a weight-raising
++	 * period: clear raising_time_left to prevent bfq_bfqq_save_state()
++	 * from assigning it a full weight-raising period. See the detailed
++	 * comments about this field in bfq_init_icq().
++	 */
++	if (bfqq->bic)
++		bfqq->bic->wr_time_left = 0;
+ 	rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
+ 	list_add_tail(&rq->queuelist, &bfqq->fifo);
+ 
+@@ -3094,6 +3688,32 @@ static void bfq_put_request(struct request *rq)
+ }
+ 
+ /*
++ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
++ * was the last process referring to said bfqq.
++ */
++static struct bfq_queue *
++bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
++{
++	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
++
++	put_io_context(bic->icq.ioc);
++
++	if (bfqq_process_refs(bfqq) == 1) {
++		bfqq->pid = current->pid;
++		bfq_clear_bfqq_coop(bfqq);
++		bfq_clear_bfqq_split_coop(bfqq);
++		return bfqq;
++	}
++
++	bic_set_bfqq(bic, NULL, 1);
++
++	bfq_put_cooperator(bfqq);
++
++	bfq_put_queue(bfqq);
++	return NULL;
++}
++
++/*
+  * Allocate bfq data structures associated with this request.
+  */
+ static int bfq_set_request(struct request_queue *q, struct request *rq,
+@@ -3105,6 +3725,7 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
+ 	const int is_sync = rq_is_sync(rq);
+ 	struct bfq_queue *bfqq;
+ 	unsigned long flags;
++	bool split = false;
+ 
+ 	might_sleep_if(gfpflags_allow_blocking(gfp_mask));
+ 
+@@ -3117,15 +3738,30 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
+ 
+ 	bfq_bic_update_cgroup(bic, bio);
+ 
++new_queue:
+ 	bfqq = bic_to_bfqq(bic, is_sync);
+ 	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
+ 		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask);
+ 		bic_set_bfqq(bic, bfqq, is_sync);
+-		if (is_sync) {
+-			if (bfqd->large_burst)
++		if (split && is_sync) {
++			if ((bic->was_in_burst_list && bfqd->large_burst) ||
++			    bic->saved_in_large_burst)
+ 				bfq_mark_bfqq_in_large_burst(bfqq);
+-			else
+-				bfq_clear_bfqq_in_large_burst(bfqq);
++			else {
++			    bfq_clear_bfqq_in_large_burst(bfqq);
++			    if (bic->was_in_burst_list)
++			       hlist_add_head(&bfqq->burst_list_node,
++				              &bfqd->burst_list);
++			}
++		}
++	} else {
++		/* If the queue was seeky for too long, break it apart. */
++		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
++			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
++			bfqq = bfq_split_bfqq(bic, bfqq);
++			split = true;
++			if (!bfqq)
++				goto new_queue;
+ 		}
+ 	}
+ 
+@@ -3137,6 +3773,26 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
+ 	rq->elv.priv[0] = bic;
+ 	rq->elv.priv[1] = bfqq;
+ 
++	/*
++	 * If a bfq_queue has only one process reference, it is owned
++	 * by only one bfq_io_cq: we can set the bic field of the
++	 * bfq_queue to the address of that structure. Also, if the
++	 * queue has just been split, mark a flag so that the
++	 * information is available to the other scheduler hooks.
++	 */
++	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
++		bfqq->bic = bic;
++		if (split) {
++			bfq_mark_bfqq_just_split(bfqq);
++			/*
++			 * If the queue has just been split from a shared
++			 * queue, restore the idle window and the possible
++			 * weight raising period.
++			 */
++			bfq_bfqq_resume_state(bfqq, bic);
++		}
++	}
++
+ 	spin_unlock_irqrestore(q->queue_lock, flags);
+ 
+ 	return 0;
+@@ -3290,6 +3946,7 @@ static void bfq_init_root_group(struct bfq_group *root_group,
+ 	root_group->my_entity = NULL;
+ 	root_group->bfqd = bfqd;
+ #endif
++	root_group->rq_pos_tree = RB_ROOT;
+ 	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ 		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+ }
+@@ -3370,6 +4027,8 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+ 	bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async;
+ 	bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync;
+ 
++	bfqd->bfq_coop_thresh = 2;
++	bfqd->bfq_failed_cooperations = 7000;
+ 	bfqd->bfq_requests_within_timer = 120;
+ 
+ 	bfqd->bfq_large_burst_thresh = 11;
+diff --git a/block/bfq.h b/block/bfq.h
+index 485d0c9..f73c942 100644
+--- a/block/bfq.h
++++ b/block/bfq.h
+@@ -183,6 +183,8 @@ struct bfq_group;
+  *                    ioprio_class value.
+  * @new_bfqq: shared bfq_queue if queue is cooperating with
+  *           one or more other queues.
++ * @pos_node: request-position tree member (see bfq_group's @rq_pos_tree).
++ * @pos_root: request-position tree root (see bfq_group's @rq_pos_tree).
+  * @sort_list: sorted list of pending requests.
+  * @next_rq: if fifo isn't expired, next request to serve.
+  * @queued: nr of requests queued in @sort_list.
+@@ -304,6 +306,26 @@ struct bfq_ttime {
+  * @ttime: associated @bfq_ttime struct
+  * @ioprio: per (request_queue, blkcg) ioprio.
+  * @blkcg_id: id of the blkcg the related io_cq belongs to.
++ * @wr_time_left: snapshot of the time left before weight raising ends
++ *                for the sync queue associated to this process; this
++ *		  snapshot is taken to remember this value while the weight
++ *		  raising is suspended because the queue is merged with a
++ *		  shared queue, and is used to set @raising_cur_max_time
++ *		  when the queue is split from the shared queue and its
++ *		  weight is raised again
++ * @saved_idle_window: same purpose as the previous field for the idle
++ *                     window
++ * @saved_IO_bound: same purpose as the previous two fields for the I/O
++ *                  bound classification of a queue
++ * @saved_in_large_burst: same purpose as the previous fields for the
++ *                        value of the field keeping the queue's belonging
++ *                        to a large burst
++ * @was_in_burst_list: true if the queue belonged to a burst list
++ *                     before its merge with another cooperating queue
++ * @cooperations: counter of consecutive successful queue merges underwent
++ *                by any of the process' @bfq_queues
++ * @failed_cooperations: counter of consecutive failed queue merges of any
++ *                       of the process' @bfq_queues
+  */
+ struct bfq_io_cq {
+ 	struct io_cq icq; /* must be the first member */
+@@ -314,6 +336,16 @@ struct bfq_io_cq {
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	uint64_t blkcg_id; /* the current blkcg ID */
+ #endif
++
++	unsigned int wr_time_left;
++	bool saved_idle_window;
++	bool saved_IO_bound;
++
++	bool saved_in_large_burst;
++	bool was_in_burst_list;
++
++	unsigned int cooperations;
++	unsigned int failed_cooperations;
+ };
+ 
+ enum bfq_device_speed {
+@@ -557,6 +589,9 @@ enum bfqq_state_flags {
+ 					 * may need softrt-next-start
+ 					 * update
+ 					 */
++	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
++	BFQ_BFQQ_FLAG_split_coop,	/* shared bfqq will be split */
++	BFQ_BFQQ_FLAG_just_split,	/* queue has just been split */
+ };
+ 
+ #define BFQ_BFQQ_FNS(name)						\
+@@ -583,6 +618,9 @@ BFQ_BFQQ_FNS(budget_new);
+ BFQ_BFQQ_FNS(IO_bound);
+ BFQ_BFQQ_FNS(in_large_burst);
+ BFQ_BFQQ_FNS(constantly_seeky);
++BFQ_BFQQ_FNS(coop);
++BFQ_BFQQ_FNS(split_coop);
++BFQ_BFQQ_FNS(just_split);
+ BFQ_BFQQ_FNS(softrt_update);
+ #undef BFQ_BFQQ_FNS
+ 
+@@ -675,6 +713,9 @@ struct bfq_group_data {
+  *                   are groups with more than one active @bfq_entity
+  *                   (see the comments to the function
+  *                   bfq_bfqq_must_not_expire()).
++ * @rq_pos_tree: rbtree sorted by next_request position, used when
++ *               determining if two or more queues have interleaving
++ *               requests (see bfq_find_close_cooperator()).
+  *
+  * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
+  * there is a set of bfq_groups, each one collecting the lower-level
+@@ -701,6 +742,8 @@ struct bfq_group {
+ 
+ 	int active_entities;
+ 
++	struct rb_root rq_pos_tree;
++
+ 	struct bfqg_stats stats;
+ 	struct bfqg_stats dead_stats;	/* stats pushed from dead children */
+ };
+@@ -711,6 +754,8 @@ struct bfq_group {
+ 
+ 	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ 	struct bfq_queue *async_idle_bfqq;
++
++	struct rb_root rq_pos_tree;
+ };
+ #endif
+ 
+@@ -787,6 +832,27 @@ static void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags)
+ 	spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+ }
+ 
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++
++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
++{
++	struct bfq_entity *group_entity = bfqq->entity.parent;
++
++	if (!group_entity)
++		group_entity = &bfqq->bfqd->root_group->entity;
++
++	return container_of(group_entity, struct bfq_group, entity);
++}
++
++#else
++
++static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
++{
++	return bfqq->bfqd->root_group;
++}
++
++#endif
++
+ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
+ static void bfq_put_queue(struct bfq_queue *bfqq);
+ static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
+-- 
+1.9.1
+
diff --git a/5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch1 b/5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch1
new file mode 100644
index 00000000..372f0937
--- /dev/null
+++ b/5004_blkck-bfq-turn-BFQ-v7r11-for-4.7.0-into-BFQ-v8-for-4.patch1
@@ -0,0 +1,6361 @@
+From 21d90fdc7488cd7c28f47b5ba759e62c697c0382 Mon Sep 17 00:00:00 2001
+From: Paolo Valente <paolo.valente@linaro.org>
+Date: Tue, 17 May 2016 08:28:04 +0200
+Subject: [PATCH 4/4] block, bfq: turn BFQ-v7r11 for 4.7.0 into BFQ-v8 for
+ 4.7.0
+
+---
+ block/Kconfig.iosched |    2 +-
+ block/bfq-cgroup.c    |  448 +++++----
+ block/bfq-iosched.c   | 2581 +++++++++++++++++++++++++++++--------------------
+ block/bfq-sched.c     |  432 +++++++--
+ block/bfq.h           |  697 +++++++------
+ 5 files changed, 2433 insertions(+), 1727 deletions(-)
+
+diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
+index f78cd1a..6d92579 100644
+--- a/block/Kconfig.iosched
++++ b/block/Kconfig.iosched
+@@ -53,7 +53,7 @@ config IOSCHED_BFQ
+ 
+ config BFQ_GROUP_IOSCHED
+ 	bool "BFQ hierarchical scheduling support"
+-	depends on CGROUPS && IOSCHED_BFQ=y
++	depends on IOSCHED_BFQ && BLK_CGROUP
+ 	default n
+ 	---help---
+ 	  Enable hierarchical scheduling in BFQ, using the blkio controller.
+diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
+index 5ee99ec..bc01663 100644
+--- a/block/bfq-cgroup.c
++++ b/block/bfq-cgroup.c
+@@ -162,7 +162,6 @@ static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
+ static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
+ {
+ 	struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq);
+-	BUG_ON(!pd);
+ 	return pd_to_bfqg(pd);
+ }
+ 
+@@ -224,14 +223,6 @@ static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int rw)
+ 	blkg_rwstat_add(&bfqg->stats.merged, rw, 1);
+ }
+ 
+-static void bfqg_stats_update_dispatch(struct bfq_group *bfqg,
+-					      uint64_t bytes, int rw)
+-{
+-	blkg_stat_add(&bfqg->stats.sectors, bytes >> 9);
+-	blkg_rwstat_add(&bfqg->stats.serviced, rw, 1);
+-	blkg_rwstat_add(&bfqg->stats.service_bytes, rw, bytes);
+-}
+-
+ static void bfqg_stats_update_completion(struct bfq_group *bfqg,
+ 			uint64_t start_time, uint64_t io_start_time, int rw)
+ {
+@@ -248,17 +239,11 @@ static void bfqg_stats_update_completion(struct bfq_group *bfqg,
+ /* @stats = 0 */
+ static void bfqg_stats_reset(struct bfqg_stats *stats)
+ {
+-	if (!stats)
+-		return;
+-
+ 	/* queued stats shouldn't be cleared */
+-	blkg_rwstat_reset(&stats->service_bytes);
+-	blkg_rwstat_reset(&stats->serviced);
+ 	blkg_rwstat_reset(&stats->merged);
+ 	blkg_rwstat_reset(&stats->service_time);
+ 	blkg_rwstat_reset(&stats->wait_time);
+ 	blkg_stat_reset(&stats->time);
+-	blkg_stat_reset(&stats->unaccounted_time);
+ 	blkg_stat_reset(&stats->avg_queue_size_sum);
+ 	blkg_stat_reset(&stats->avg_queue_size_samples);
+ 	blkg_stat_reset(&stats->dequeue);
+@@ -268,21 +253,19 @@ static void bfqg_stats_reset(struct bfqg_stats *stats)
+ }
+ 
+ /* @to += @from */
+-static void bfqg_stats_merge(struct bfqg_stats *to, struct bfqg_stats *from)
++static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
+ {
+ 	if (!to || !from)
+ 		return;
+ 
+ 	/* queued stats shouldn't be cleared */
+-	blkg_rwstat_add_aux(&to->service_bytes, &from->service_bytes);
+-	blkg_rwstat_add_aux(&to->serviced, &from->serviced);
+ 	blkg_rwstat_add_aux(&to->merged, &from->merged);
+ 	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
+ 	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
+ 	blkg_stat_add_aux(&from->time, &from->time);
+-	blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
+ 	blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
+-	blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
++	blkg_stat_add_aux(&to->avg_queue_size_samples,
++			  &from->avg_queue_size_samples);
+ 	blkg_stat_add_aux(&to->dequeue, &from->dequeue);
+ 	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
+ 	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
+@@ -308,10 +291,8 @@ static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
+ 	if (unlikely(!parent))
+ 		return;
+ 
+-	bfqg_stats_merge(&parent->dead_stats, &bfqg->stats);
+-	bfqg_stats_merge(&parent->dead_stats, &bfqg->dead_stats);
++	bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
+ 	bfqg_stats_reset(&bfqg->stats);
+-	bfqg_stats_reset(&bfqg->dead_stats);
+ }
+ 
+ static void bfq_init_entity(struct bfq_entity *entity,
+@@ -332,15 +313,11 @@ static void bfq_init_entity(struct bfq_entity *entity,
+ 
+ static void bfqg_stats_exit(struct bfqg_stats *stats)
+ {
+-	blkg_rwstat_exit(&stats->service_bytes);
+-	blkg_rwstat_exit(&stats->serviced);
+ 	blkg_rwstat_exit(&stats->merged);
+ 	blkg_rwstat_exit(&stats->service_time);
+ 	blkg_rwstat_exit(&stats->wait_time);
+ 	blkg_rwstat_exit(&stats->queued);
+-	blkg_stat_exit(&stats->sectors);
+ 	blkg_stat_exit(&stats->time);
+-	blkg_stat_exit(&stats->unaccounted_time);
+ 	blkg_stat_exit(&stats->avg_queue_size_sum);
+ 	blkg_stat_exit(&stats->avg_queue_size_samples);
+ 	blkg_stat_exit(&stats->dequeue);
+@@ -351,15 +328,11 @@ static void bfqg_stats_exit(struct bfqg_stats *stats)
+ 
+ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
+ {
+-	if (blkg_rwstat_init(&stats->service_bytes, gfp) ||
+-	    blkg_rwstat_init(&stats->serviced, gfp) ||
+-	    blkg_rwstat_init(&stats->merged, gfp) ||
++	if (blkg_rwstat_init(&stats->merged, gfp) ||
+ 	    blkg_rwstat_init(&stats->service_time, gfp) ||
+ 	    blkg_rwstat_init(&stats->wait_time, gfp) ||
+ 	    blkg_rwstat_init(&stats->queued, gfp) ||
+-	    blkg_stat_init(&stats->sectors, gfp) ||
+ 	    blkg_stat_init(&stats->time, gfp) ||
+-	    blkg_stat_init(&stats->unaccounted_time, gfp) ||
+ 	    blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
+ 	    blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
+ 	    blkg_stat_init(&stats->dequeue, gfp) ||
+@@ -374,20 +347,36 @@ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
+ }
+ 
+ static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
+- {
++{
+ 	return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
+- }
++}
+ 
+ static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
+ {
+ 	return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
+ }
+ 
++static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
++{
++	struct bfq_group_data *bgd;
++
++	bgd = kzalloc(sizeof(*bgd), GFP_KERNEL);
++	if (!bgd)
++		return NULL;
++	return &bgd->pd;
++}
++
+ static void bfq_cpd_init(struct blkcg_policy_data *cpd)
+ {
+ 	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
+ 
+-	d->weight = BFQ_DEFAULT_GRP_WEIGHT;
++	d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
++		CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
++}
++
++static void bfq_cpd_free(struct blkcg_policy_data *cpd)
++{
++	kfree(cpd_to_bfqgd(cpd));
+ }
+ 
+ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
+@@ -398,8 +387,7 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
+ 	if (!bfqg)
+ 		return NULL;
+ 
+-	if (bfqg_stats_init(&bfqg->stats, gfp) ||
+-	    bfqg_stats_init(&bfqg->dead_stats, gfp)) {
++	if (bfqg_stats_init(&bfqg->stats, gfp)) {
+ 		kfree(bfqg);
+ 		return NULL;
+ 	}
+@@ -407,27 +395,20 @@ static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
+ 	return &bfqg->pd;
+ }
+ 
+-static void bfq_group_set_parent(struct bfq_group *bfqg,
+-					struct bfq_group *parent)
++static void bfq_pd_init(struct blkg_policy_data *pd)
+ {
++	struct blkcg_gq *blkg;
++	struct bfq_group *bfqg;
++	struct bfq_data *bfqd;
+ 	struct bfq_entity *entity;
++	struct bfq_group_data *d;
+ 
+-	BUG_ON(!parent);
+-	BUG_ON(!bfqg);
+-	BUG_ON(bfqg == parent);
+-
++	blkg = pd_to_blkg(pd);
++	BUG_ON(!blkg);
++	bfqg = blkg_to_bfqg(blkg);
++	bfqd = blkg->q->elevator->elevator_data;
+ 	entity = &bfqg->entity;
+-	entity->parent = parent->my_entity;
+-	entity->sched_data = &parent->sched_data;
+-}
+-
+-static void bfq_pd_init(struct blkg_policy_data *pd)
+-{
+-	struct blkcg_gq *blkg = pd_to_blkg(pd);
+-	struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+-	struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
+-	struct bfq_entity *entity = &bfqg->entity;
+-	struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
++	d = blkcg_to_bfqgd(blkg->blkcg);
+ 
+ 	entity->orig_weight = entity->weight = entity->new_weight = d->weight;
+ 	entity->my_sched_data = &bfqg->sched_data;
+@@ -445,45 +426,28 @@ static void bfq_pd_free(struct blkg_policy_data *pd)
+ 	struct bfq_group *bfqg = pd_to_bfqg(pd);
+ 
+ 	bfqg_stats_exit(&bfqg->stats);
+-	bfqg_stats_exit(&bfqg->dead_stats);
+-
+ 	return kfree(bfqg);
+ }
+ 
+-/* offset delta from bfqg->stats to bfqg->dead_stats */
+-static const int dead_stats_off_delta = offsetof(struct bfq_group, dead_stats) -
+-					offsetof(struct bfq_group, stats);
+-
+-/* to be used by recursive prfill, sums live and dead stats recursively */
+-static u64 bfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
++static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
+ {
+-	u64 sum = 0;
++	struct bfq_group *bfqg = pd_to_bfqg(pd);
+ 
+-	sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off);
+-	sum += blkg_stat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq,
+-				       off + dead_stats_off_delta);
+-	return sum;
++	bfqg_stats_reset(&bfqg->stats);
+ }
+ 
+-/* to be used by recursive prfill, sums live and dead rwstats recursively */
+-static struct blkg_rwstat bfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
+-						       int off)
++static void bfq_group_set_parent(struct bfq_group *bfqg,
++					struct bfq_group *parent)
+ {
+-	struct blkg_rwstat a, b;
+-
+-	a = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off);
+-	b = blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq,
+-				      off + dead_stats_off_delta);
+-	blkg_rwstat_add_aux(&a, &b);
+-	return a;
+-}
++	struct bfq_entity *entity;
+ 
+-static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
+-{
+-	struct bfq_group *bfqg = pd_to_bfqg(pd);
++	BUG_ON(!parent);
++	BUG_ON(!bfqg);
++	BUG_ON(bfqg == parent);
+ 
+-	bfqg_stats_reset(&bfqg->stats);
+-	bfqg_stats_reset(&bfqg->dead_stats);
++	entity = &bfqg->entity;
++	entity->parent = parent->my_entity;
++	entity->sched_data = &parent->sched_data;
+ }
+ 
+ static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+@@ -531,13 +495,18 @@ static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+ 	return bfqg;
+ }
+ 
+-static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
++static void bfq_pos_tree_add_move(struct bfq_data *bfqd,
++				  struct bfq_queue *bfqq);
++
++static void bfq_bfqq_expire(struct bfq_data *bfqd,
++			    struct bfq_queue *bfqq,
++			    bool compensate,
++			    enum bfqq_expiration reason);
+ 
+ /**
+  * bfq_bfqq_move - migrate @bfqq to @bfqg.
+  * @bfqd: queue descriptor.
+  * @bfqq: the queue to move.
+- * @entity: @bfqq's entity.
+  * @bfqg: the group to move to.
+  *
+  * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
+@@ -548,26 +517,40 @@ static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+  * rcu_read_lock()).
+  */
+ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+-			  struct bfq_entity *entity, struct bfq_group *bfqg)
++			  struct bfq_group *bfqg)
+ {
+-	int busy, resume;
++	struct bfq_entity *entity = &bfqq->entity;
+ 
+-	busy = bfq_bfqq_busy(bfqq);
+-	resume = !RB_EMPTY_ROOT(&bfqq->sort_list);
+-
+-	BUG_ON(resume && !entity->on_st);
+-	BUG_ON(busy && !resume && entity->on_st &&
++	BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list));
++	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st);
++	BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list)
++	       && entity->on_st &&
+ 	       bfqq != bfqd->in_service_queue);
++	BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue);
++
++	/* If bfqq is empty, then bfq_bfqq_expire also invokes
++	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
++	 * from data structures related to current group. Otherwise we
++	 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
++	 * we do below.
++	 */
++	if (bfqq == bfqd->in_service_queue)
++		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
++				false, BFQ_BFQQ_PREEMPTED);
++
++	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
++	    && &bfq_entity_service_tree(entity)->idle !=
++	       entity->tree);
+ 
+-	if (busy) {
+-		BUG_ON(atomic_read(&bfqq->ref) < 2);
++	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
+ 
+-		if (!resume)
+-			bfq_del_bfqq_busy(bfqd, bfqq, 0);
+-		else
+-			bfq_deactivate_bfqq(bfqd, bfqq, 0);
+-	} else if (entity->on_st)
++	if (bfq_bfqq_busy(bfqq))
++		bfq_deactivate_bfqq(bfqd, bfqq, 0);
++	else if (entity->on_st) {
++		BUG_ON(&bfq_entity_service_tree(entity)->idle !=
++		       entity->tree);
+ 		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
++	}
+ 	bfqg_put(bfqq_group(bfqq));
+ 
+ 	/*
+@@ -579,14 +562,17 @@ static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	entity->sched_data = &bfqg->sched_data;
+ 	bfqg_get(bfqg);
+ 
+-	if (busy) {
++	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
++	if (bfq_bfqq_busy(bfqq)) {
+ 		bfq_pos_tree_add_move(bfqd, bfqq);
+-		if (resume)
+-			bfq_activate_bfqq(bfqd, bfqq);
++		bfq_activate_bfqq(bfqd, bfqq);
+ 	}
+ 
+ 	if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
+ 		bfq_schedule_dispatch(bfqd);
++	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
++	       && &bfq_entity_service_tree(entity)->idle !=
++	       entity->tree);
+ }
+ 
+ /**
+@@ -621,7 +607,8 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
+ 			bic_set_bfqq(bic, NULL, 0);
+ 			bfq_log_bfqq(bfqd, async_bfqq,
+ 				     "bic_change_group: %p %d",
+-				     async_bfqq, atomic_read(&async_bfqq->ref));
++				     async_bfqq,
++				     async_bfqq->ref);
+ 			bfq_put_queue(async_bfqq);
+ 		}
+ 	}
+@@ -629,7 +616,7 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
+ 	if (sync_bfqq) {
+ 		entity = &sync_bfqq->entity;
+ 		if (entity->sched_data != &bfqg->sched_data)
+-			bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg);
++			bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
+ 	}
+ 
+ 	return bfqg;
+@@ -638,25 +625,23 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
+ static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
+ {
+ 	struct bfq_data *bfqd = bic_to_bfqd(bic);
+-	struct blkcg *blkcg;
+ 	struct bfq_group *bfqg = NULL;
+-	uint64_t id;
++	uint64_t serial_nr;
+ 
+ 	rcu_read_lock();
+-	blkcg = bio_blkcg(bio);
+-	id = blkcg->css.serial_nr;
+-	rcu_read_unlock();
++	serial_nr = bio_blkcg(bio)->css.serial_nr;
+ 
+ 	/*
+ 	 * Check whether blkcg has changed.  The condition may trigger
+ 	 * spuriously on a newly created cic but there's no harm.
+ 	 */
+-	if (unlikely(!bfqd) || likely(bic->blkcg_id == id))
+-		return;
++	if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
++		goto out;
+ 
+-	bfqg = __bfq_bic_change_cgroup(bfqd, bic, blkcg);
+-	BUG_ON(!bfqg);
+-	bic->blkcg_id = id;
++	bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
++	bic->blkcg_serial_nr = serial_nr;
++out:
++	rcu_read_unlock();
+ }
+ 
+ /**
+@@ -682,8 +667,7 @@ static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
+ 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ 
+ 	BUG_ON(!bfqq);
+-	bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group);
+-	return;
++	bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
+ }
+ 
+ /**
+@@ -711,16 +695,15 @@ static void bfq_reparent_active_entities(struct bfq_data *bfqd,
+ 	if (bfqg->sched_data.in_service_entity)
+ 		bfq_reparent_leaf_entity(bfqd,
+ 			bfqg->sched_data.in_service_entity);
+-
+-	return;
+ }
+ 
+ /**
+- * bfq_destroy_group - destroy @bfqg.
+- * @bfqg: the group being destroyed.
++ * bfq_pd_offline - deactivate the entity associated with @pd,
++ *		    and reparent its children entities.
++ * @pd: descriptor of the policy going offline.
+  *
+- * Destroy @bfqg, making sure that it is not referenced from its parent.
+- * blkio already grabs the queue_lock for us, so no need to use RCU-based magic
++ * blkio already grabs the queue_lock for us, so no need to use
++ * RCU-based magic
+  */
+ static void bfq_pd_offline(struct blkg_policy_data *pd)
+ {
+@@ -779,6 +762,12 @@ static void bfq_pd_offline(struct blkg_policy_data *pd)
+ 	bfq_put_async_queues(bfqd, bfqg);
+ 	BUG_ON(entity->tree);
+ 
++	/*
++	 * @blkg is going offline and will be ignored by
++	 * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
++	 * that they don't get lost.  If IOs complete after this point, the
++	 * stats for them will be lost.  Oh well...
++	 */
+ 	bfqg_stats_xfer_dead(bfqg);
+ }
+ 
+@@ -788,46 +777,35 @@ static void bfq_end_wr_async(struct bfq_data *bfqd)
+ 
+ 	list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
+ 		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
++		BUG_ON(!bfqg);
+ 
+ 		bfq_end_wr_async_queues(bfqd, bfqg);
+ 	}
+ 	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+ }
+ 
+-static u64 bfqio_cgroup_weight_read(struct cgroup_subsys_state *css,
+-				       struct cftype *cftype)
+-{
+-	struct blkcg *blkcg = css_to_blkcg(css);
+-	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+-	int ret = -EINVAL;
+-
+-	spin_lock_irq(&blkcg->lock);
+-	ret = bfqgd->weight;
+-	spin_unlock_irq(&blkcg->lock);
+-
+-	return ret;
+-}
+-
+-static int bfqio_cgroup_weight_read_dfl(struct seq_file *sf, void *v)
++static int bfq_io_show_weight(struct seq_file *sf, void *v)
+ {
+ 	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
+ 	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
++	unsigned int val = 0;
+ 
+-	spin_lock_irq(&blkcg->lock);
+-	seq_printf(sf, "%u\n", bfqgd->weight);
+-	spin_unlock_irq(&blkcg->lock);
++	if (bfqgd)
++		val = bfqgd->weight;
++
++	seq_printf(sf, "%u\n", val);
+ 
+ 	return 0;
+ }
+ 
+-static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css,
+-					struct cftype *cftype,
+-					u64 val)
++static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
++				    struct cftype *cftype,
++				    u64 val)
+ {
+ 	struct blkcg *blkcg = css_to_blkcg(css);
+ 	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+ 	struct blkcg_gq *blkg;
+-	int ret = -EINVAL;
++	int ret = -ERANGE;
+ 
+ 	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
+ 		return ret;
+@@ -837,6 +815,7 @@ static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css,
+ 	bfqgd->weight = (unsigned short)val;
+ 	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
+ 		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
++
+ 		if (!bfqg)
+ 			continue;
+ 		/*
+@@ -871,13 +850,18 @@ static int bfqio_cgroup_weight_write(struct cgroup_subsys_state *css,
+ 	return ret;
+ }
+ 
+-static ssize_t bfqio_cgroup_weight_write_dfl(struct kernfs_open_file *of,
+-					     char *buf, size_t nbytes,
+-					     loff_t off)
++static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
++				 char *buf, size_t nbytes,
++				 loff_t off)
+ {
++	u64 weight;
+ 	/* First unsigned long found in the file is used */
+-	return bfqio_cgroup_weight_write(of_css(of), NULL,
+-					 simple_strtoull(strim(buf), NULL, 0));
++	int ret = kstrtoull(strim(buf), 0, &weight);
++
++	if (ret)
++		return ret;
++
++	return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
+ }
+ 
+ static int bfqg_print_stat(struct seq_file *sf, void *v)
+@@ -897,16 +881,17 @@ static int bfqg_print_rwstat(struct seq_file *sf, void *v)
+ static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
+ 				      struct blkg_policy_data *pd, int off)
+ {
+-	u64 sum = bfqg_stat_pd_recursive_sum(pd, off);
+-
++	u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
++					  &blkcg_policy_bfq, off);
+ 	return __blkg_prfill_u64(sf, pd, sum);
+ }
+ 
+ static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
+ 					struct blkg_policy_data *pd, int off)
+ {
+-	struct blkg_rwstat sum = bfqg_rwstat_pd_recursive_sum(pd, off);
+-
++	struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
++							   &blkcg_policy_bfq,
++							   off);
+ 	return __blkg_prfill_rwstat(sf, pd, &sum);
+ }
+ 
+@@ -926,6 +911,41 @@ static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
+ 	return 0;
+ }
+ 
++static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
++			       int off)
++{
++	u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
++
++	return __blkg_prfill_u64(sf, pd, sum >> 9);
++}
++
++static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
++			  bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
++	return 0;
++}
++
++static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
++					 struct blkg_policy_data *pd, int off)
++{
++	struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
++					offsetof(struct blkcg_gq, stat_bytes));
++	u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
++		atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
++
++	return __blkg_prfill_u64(sf, pd, sum >> 9);
++}
++
++static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
++{
++	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
++			  bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
++			  false);
++	return 0;
++}
++
++
+ static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
+ 				      struct blkg_policy_data *pd, int off)
+ {
+@@ -950,7 +970,8 @@ static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
+ 	return 0;
+ }
+ 
+-static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
++static struct bfq_group *
++bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
+ {
+ 	int ret;
+ 
+@@ -958,41 +979,18 @@ static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int n
+ 	if (ret)
+ 		return NULL;
+ 
+-        return blkg_to_bfqg(bfqd->queue->root_blkg);
+-}
+-
+-static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
+-{
+-        struct bfq_group_data *bgd;
+-
+-        bgd = kzalloc(sizeof(*bgd), GFP_KERNEL);
+-        if (!bgd)
+-                return NULL;
+-        return &bgd->pd;
++	return blkg_to_bfqg(bfqd->queue->root_blkg);
+ }
+ 
+-static void bfq_cpd_free(struct blkcg_policy_data *cpd)
+-{
+-        kfree(cpd_to_bfqgd(cpd));
+-}
+-
+-static struct cftype bfqio_files_dfl[] = {
++static struct cftype bfq_blkcg_legacy_files[] = {
+ 	{
+-		.name = "weight",
++		.name = "bfq.weight",
+ 		.flags = CFTYPE_NOT_ON_ROOT,
+-		.seq_show = bfqio_cgroup_weight_read_dfl,
+-		.write = bfqio_cgroup_weight_write_dfl,
++		.seq_show = bfq_io_show_weight,
++		.write_u64 = bfq_io_set_weight_legacy,
+ 	},
+-	{} /* terminate */
+-};
+ 
+-static struct cftype bfqio_files[] = {
+-	{
+-		.name = "bfq.weight",
+-		.read_u64 = bfqio_cgroup_weight_read,
+-		.write_u64 = bfqio_cgroup_weight_write,
+-	},
+-	/* statistics, cover only the tasks in the bfqg */
++	/* statistics, covers only the tasks in the bfqg */
+ 	{
+ 		.name = "bfq.time",
+ 		.private = offsetof(struct bfq_group, stats.time),
+@@ -1000,18 +998,17 @@ static struct cftype bfqio_files[] = {
+ 	},
+ 	{
+ 		.name = "bfq.sectors",
+-		.private = offsetof(struct bfq_group, stats.sectors),
+-		.seq_show = bfqg_print_stat,
++		.seq_show = bfqg_print_stat_sectors,
+ 	},
+ 	{
+ 		.name = "bfq.io_service_bytes",
+-		.private = offsetof(struct bfq_group, stats.service_bytes),
+-		.seq_show = bfqg_print_rwstat,
++		.private = (unsigned long)&blkcg_policy_bfq,
++		.seq_show = blkg_print_stat_bytes,
+ 	},
+ 	{
+ 		.name = "bfq.io_serviced",
+-		.private = offsetof(struct bfq_group, stats.serviced),
+-		.seq_show = bfqg_print_rwstat,
++		.private = (unsigned long)&blkcg_policy_bfq,
++		.seq_show = blkg_print_stat_ios,
+ 	},
+ 	{
+ 		.name = "bfq.io_service_time",
+@@ -1042,18 +1039,17 @@ static struct cftype bfqio_files[] = {
+ 	},
+ 	{
+ 		.name = "bfq.sectors_recursive",
+-		.private = offsetof(struct bfq_group, stats.sectors),
+-		.seq_show = bfqg_print_stat_recursive,
++		.seq_show = bfqg_print_stat_sectors_recursive,
+ 	},
+ 	{
+ 		.name = "bfq.io_service_bytes_recursive",
+-		.private = offsetof(struct bfq_group, stats.service_bytes),
+-		.seq_show = bfqg_print_rwstat_recursive,
++		.private = (unsigned long)&blkcg_policy_bfq,
++		.seq_show = blkg_print_stat_bytes_recursive,
+ 	},
+ 	{
+ 		.name = "bfq.io_serviced_recursive",
+-		.private = offsetof(struct bfq_group, stats.serviced),
+-		.seq_show = bfqg_print_rwstat_recursive,
++		.private = (unsigned long)&blkcg_policy_bfq,
++		.seq_show = blkg_print_stat_ios_recursive,
+ 	},
+ 	{
+ 		.name = "bfq.io_service_time_recursive",
+@@ -1099,32 +1095,35 @@ static struct cftype bfqio_files[] = {
+ 		.private = offsetof(struct bfq_group, stats.dequeue),
+ 		.seq_show = bfqg_print_stat,
+ 	},
+-	{
+-		.name = "bfq.unaccounted_time",
+-		.private = offsetof(struct bfq_group, stats.unaccounted_time),
+-		.seq_show = bfqg_print_stat,
+-	},
+ 	{ }	/* terminate */
+ };
+ 
+-static struct blkcg_policy blkcg_policy_bfq = {
+-       .dfl_cftypes            = bfqio_files_dfl,
+-       .legacy_cftypes         = bfqio_files,
+-
+-       .pd_alloc_fn            = bfq_pd_alloc,
+-       .pd_init_fn             = bfq_pd_init,
+-       .pd_offline_fn          = bfq_pd_offline,
+-       .pd_free_fn             = bfq_pd_free,
+-       .pd_reset_stats_fn      = bfq_pd_reset_stats,
+-
+-       .cpd_alloc_fn           = bfq_cpd_alloc,
+-       .cpd_init_fn            = bfq_cpd_init,
+-       .cpd_bind_fn	       = bfq_cpd_init,
+-       .cpd_free_fn            = bfq_cpd_free,
+-
++static struct cftype bfq_blkg_files[] = {
++	{
++		.name = "bfq.weight",
++		.flags = CFTYPE_NOT_ON_ROOT,
++		.seq_show = bfq_io_show_weight,
++		.write = bfq_io_set_weight,
++	},
++	{} /* terminate */
+ };
+ 
+-#else
++#else /* CONFIG_BFQ_GROUP_IOSCHED */
++
++static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
++			struct bfq_queue *bfqq, int rw) { }
++static inline void bfqg_stats_update_io_remove(struct bfq_group *bfqg, int rw) { }
++static inline void bfqg_stats_update_io_merged(struct bfq_group *bfqg, int rw) { }
++static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
++			uint64_t start_time, uint64_t io_start_time, int rw) { }
++static inline void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
++struct bfq_group *curr_bfqg) { }
++static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
++static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
++static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
++static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
++static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
++static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
+ 
+ static void bfq_init_entity(struct bfq_entity *entity,
+ 			    struct bfq_group *bfqg)
+@@ -1146,29 +1145,22 @@ bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
+ 	return bfqd->root_group;
+ }
+ 
+-static void bfq_bfqq_move(struct bfq_data *bfqd,
+-			  struct bfq_queue *bfqq,
+-			  struct bfq_entity *entity,
+-			  struct bfq_group *bfqg)
+-{
+-}
+-
+ static void bfq_end_wr_async(struct bfq_data *bfqd)
+ {
+ 	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+ }
+ 
+-static void bfq_disconnect_groups(struct bfq_data *bfqd)
+-{
+-	bfq_put_async_queues(bfqd, bfqd->root_group);
+-}
+-
+ static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+                                               struct blkcg *blkcg)
+ {
+ 	return bfqd->root_group;
+ }
+ 
++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
++{
++	return bfqq->bfqd->root_group;
++}
++
+ static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
+ {
+ 	struct bfq_group *bfqg;
+diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
+index d1f648d..5469442 100644
+--- a/block/bfq-iosched.c
++++ b/block/bfq-iosched.c
+@@ -7,25 +7,26 @@
+  * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+  *		      Paolo Valente <paolo.valente@unimore.it>
+  *
+- * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ * Copyright (C) 2016 Paolo Valente <paolo.valente@unimore.it>
+  *
+  * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
+  * file.
+  *
+- * BFQ is a proportional-share storage-I/O scheduling algorithm based on
+- * the slice-by-slice service scheme of CFQ. But BFQ assigns budgets,
+- * measured in number of sectors, to processes instead of time slices. The
+- * device is not granted to the in-service process for a given time slice,
+- * but until it has exhausted its assigned budget. This change from the time
+- * to the service domain allows BFQ to distribute the device throughput
+- * among processes as desired, without any distortion due to ZBR, workload
+- * fluctuations or other factors. BFQ uses an ad hoc internal scheduler,
+- * called B-WF2Q+, to schedule processes according to their budgets. More
+- * precisely, BFQ schedules queues associated to processes. Thanks to the
+- * accurate policy of B-WF2Q+, BFQ can afford to assign high budgets to
+- * I/O-bound processes issuing sequential requests (to boost the
+- * throughput), and yet guarantee a low latency to interactive and soft
+- * real-time applications.
++ * BFQ is a proportional-share storage-I/O scheduling algorithm based
++ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
++ * budgets, measured in number of sectors, to processes instead of
++ * time slices. The device is not granted to the in-service process
++ * for a given time slice, but until it has exhausted its assigned
++ * budget. This change from the time to the service domain enables BFQ
++ * to distribute the device throughput among processes as desired,
++ * without any distortion due to throughput fluctuations, or to device
++ * internal queueing. BFQ uses an ad hoc internal scheduler, called
++ * B-WF2Q+, to schedule processes according to their budgets. More
++ * precisely, BFQ schedules queues associated with processes. Thanks to
++ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
++ * budgets to I/O-bound processes issuing sequential requests (to
++ * boost the throughput), and yet guarantee a low latency to
++ * interactive and soft real-time applications.
+  *
+  * BFQ is described in [1], where also a reference to the initial, more
+  * theoretical paper on BFQ can be found. The interested reader can find
+@@ -87,7 +88,6 @@ static const int bfq_stats_min_budgets = 194;
+ 
+ /* Default maximum budget values, in sectors and number of requests. */
+ static const int bfq_default_max_budget = 16 * 1024;
+-static const int bfq_max_budget_async_rq = 4;
+ 
+ /*
+  * Async to sync throughput distribution is controlled as follows:
+@@ -97,8 +97,7 @@ static const int bfq_max_budget_async_rq = 4;
+ static const int bfq_async_charge_factor = 10;
+ 
+ /* Default timeout values, in jiffies, approximating CFQ defaults. */
+-static const int bfq_timeout_sync = HZ / 8;
+-static int bfq_timeout_async = HZ / 25;
++static const int bfq_timeout = HZ / 8;
+ 
+ struct kmem_cache *bfq_pool;
+ 
+@@ -109,8 +108,9 @@ struct kmem_cache *bfq_pool;
+ #define BFQ_HW_QUEUE_THRESHOLD	4
+ #define BFQ_HW_QUEUE_SAMPLES	32
+ 
+-#define BFQQ_SEEK_THR	 (sector_t)(8 * 1024)
+-#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR)
++#define BFQQ_SEEK_THR	 	(sector_t)(8 * 100)
++#define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
++#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 32/8)
+ 
+ /* Min samples used for peak rate estimation (for autotuning). */
+ #define BFQ_PEAK_RATE_SAMPLES	32
+@@ -141,16 +141,24 @@ struct kmem_cache *bfq_pool;
+  * The device's speed class is dynamically (re)detected in
+  * bfq_update_peak_rate() every time the estimated peak rate is updated.
+  *
+- * In the following definitions, R_slow[0]/R_fast[0] and T_slow[0]/T_fast[0]
+- * are the reference values for a slow/fast rotational device, whereas
+- * R_slow[1]/R_fast[1] and T_slow[1]/T_fast[1] are the reference values for
+- * a slow/fast non-rotational device. Finally, device_speed_thresh are the
+- * thresholds used to switch between speed classes.
++ * In the following definitions, R_slow[0]/R_fast[0] and
++ * T_slow[0]/T_fast[0] are the reference values for a slow/fast
++ * rotational device, whereas R_slow[1]/R_fast[1] and
++ * T_slow[1]/T_fast[1] are the reference values for a slow/fast
++ * non-rotational device. Finally, device_speed_thresh are the
++ * thresholds used to switch between speed classes. The reference
++ * rates are not the actual peak rates of the devices used as a
++ * reference, but slightly lower values. The reason for using these
++ * slightly lower values is that the peak-rate estimator tends to
++ * yield slightly lower values than the actual peak rate (it can yield
++ * the actual peak rate only if there is only one process doing I/O,
++ * and the process does sequential I/O).
++ *
+  * Both the reference peak rates and the thresholds are measured in
+  * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
+  */
+-static int R_slow[2] = {1536, 10752};
+-static int R_fast[2] = {17415, 34791};
++static int R_slow[2] = {1000, 10700};
++static int R_fast[2] = {14000, 33000};
+ /*
+  * To improve readability, a conversion function is used to initialize the
+  * following arrays, which entails that they can be initialized only in a
+@@ -410,11 +418,7 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd)
+  */
+ static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
+ {
+-	return
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+-		!bfqd->active_numerous_groups &&
+-#endif
+-		!bfq_differentiated_weights(bfqd);
++	return !bfq_differentiated_weights(bfqd);
+ }
+ 
+ /*
+@@ -534,9 +538,19 @@ static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
+ static unsigned long bfq_serv_to_charge(struct request *rq,
+ 					struct bfq_queue *bfqq)
+ {
+-	return blk_rq_sectors(rq) *
+-		(1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) *
+-		bfq_async_charge_factor));
++	if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1)
++		return blk_rq_sectors(rq);
++
++	/*
++	 * If there are no weight-raised queues, then amplify service
++	 * by just the async charge factor; otherwise amplify service
++	 * by twice the async charge factor, to further reduce latency
++	 * for weight-raised queues.
++	 */
++	if (bfqq->bfqd->wr_busy_queues == 0)
++		return blk_rq_sectors(rq) * bfq_async_charge_factor;
++
++	return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor;
+ }
+ 
+ /**
+@@ -591,12 +605,23 @@ static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
+ 	dur = bfqd->RT_prod;
+ 	do_div(dur, bfqd->peak_rate);
+ 
+-	return dur;
+-}
++	/*
++	 * Limit duration between 3 and 13 seconds. Tests show that
++	 * higher values than 13 seconds often yield the opposite of
++	 * the desired result, i.e., worsen responsiveness by letting
++	 * non-interactive and non-soft-real-time applications
++	 * preserve weight raising for a too long time interval.
++	 *
++	 * On the other end, lower values than 3 seconds make it
++	 * difficult for most interactive tasks to complete their jobs
++	 * before weight-raising finishes.
++	 */
++	if (dur > msecs_to_jiffies(13000))
++		dur = msecs_to_jiffies(13000);
++	else if (dur < msecs_to_jiffies(3000))
++		dur = msecs_to_jiffies(3000);
+ 
+-static unsigned bfq_bfqq_cooperations(struct bfq_queue *bfqq)
+-{
+-	return bfqq->bic ? bfqq->bic->cooperations : 0;
++	return dur;
+ }
+ 
+ static void
+@@ -606,31 +631,11 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
+ 		bfq_mark_bfqq_idle_window(bfqq);
+ 	else
+ 		bfq_clear_bfqq_idle_window(bfqq);
++
+ 	if (bic->saved_IO_bound)
+ 		bfq_mark_bfqq_IO_bound(bfqq);
+ 	else
+ 		bfq_clear_bfqq_IO_bound(bfqq);
+-	/* Assuming that the flag in_large_burst is already correctly set */
+-	if (bic->wr_time_left && bfqq->bfqd->low_latency &&
+-	    !bfq_bfqq_in_large_burst(bfqq) &&
+-	    bic->cooperations < bfqq->bfqd->bfq_coop_thresh) {
+-		/*
+-		 * Start a weight raising period with the duration given by
+-		 * the raising_time_left snapshot.
+-		 */
+-		if (bfq_bfqq_busy(bfqq))
+-			bfqq->bfqd->wr_busy_queues++;
+-		bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff;
+-		bfqq->wr_cur_max_time = bic->wr_time_left;
+-		bfqq->last_wr_start_finish = jiffies;
+-		bfqq->entity.prio_changed = 1;
+-	}
+-	/*
+-	 * Clear wr_time_left to prevent bfq_bfqq_save_state() from
+-	 * getting confused about the queue's need of a weight-raising
+-	 * period.
+-	 */
+-	bic->wr_time_left = 0;
+ }
+ 
+ static int bfqq_process_refs(struct bfq_queue *bfqq)
+@@ -640,7 +645,7 @@ static int bfqq_process_refs(struct bfq_queue *bfqq)
+ 	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
+ 
+ 	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
+-	process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st;
++	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
+ 	BUG_ON(process_refs < 0);
+ 	return process_refs;
+ }
+@@ -655,6 +660,7 @@ static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		hlist_del_init(&item->burst_list_node);
+ 	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+ 	bfqd->burst_size = 1;
++	bfqd->burst_parent_entity = bfqq->entity.parent;
+ }
+ 
+ /* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
+@@ -663,6 +669,10 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 	/* Increment burst size to take into account also bfqq */
+ 	bfqd->burst_size++;
+ 
++	bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
++
++	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
++
+ 	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
+ 		struct bfq_queue *pos, *bfqq_item;
+ 		struct hlist_node *n;
+@@ -672,15 +682,19 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		 * other to consider this burst as large.
+ 		 */
+ 		bfqd->large_burst = true;
++		bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
+ 
+ 		/*
+ 		 * We can now mark all queues in the burst list as
+ 		 * belonging to a large burst.
+ 		 */
+ 		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
+-				     burst_list_node)
++				     burst_list_node) {
+ 		        bfq_mark_bfqq_in_large_burst(bfqq_item);
++			bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
++		}
+ 		bfq_mark_bfqq_in_large_burst(bfqq);
++		bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
+ 
+ 		/*
+ 		 * From now on, and until the current burst finishes, any
+@@ -692,67 +706,79 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
+ 					  burst_list_node)
+ 			hlist_del_init(&pos->burst_list_node);
+-	} else /* burst not yet large: add bfqq to the burst list */
++	} else /*
++		* Burst not yet large: add bfqq to the burst list. Do
++		* not increment the ref counter for bfqq, because bfqq
++		* is removed from the burst list before freeing bfqq
++		* in put_queue.
++		*/
+ 		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+ }
+ 
+ /*
+- * If many queues happen to become active shortly after each other, then,
+- * to help the processes associated to these queues get their job done as
+- * soon as possible, it is usually better to not grant either weight-raising
+- * or device idling to these queues. In this comment we describe, firstly,
+- * the reasons why this fact holds, and, secondly, the next function, which
+- * implements the main steps needed to properly mark these queues so that
+- * they can then be treated in a different way.
++ * If many queues belonging to the same group happen to be created
++ * shortly after each other, then the processes associated with these
++ * queues have typically a common goal. In particular, bursts of queue
++ * creations are usually caused by services or applications that spawn
++ * many parallel threads/processes. Examples are systemd during boot,
++ * or git grep. To help these processes get their job done as soon as
++ * possible, it is usually better to not grant either weight-raising
++ * or device idling to their queues.
+  *
+- * As for the terminology, we say that a queue becomes active, i.e.,
+- * switches from idle to backlogged, either when it is created (as a
+- * consequence of the arrival of an I/O request), or, if already existing,
+- * when a new request for the queue arrives while the queue is idle.
+- * Bursts of activations, i.e., activations of different queues occurring
+- * shortly after each other, are typically caused by services or applications
+- * that spawn or reactivate many parallel threads/processes. Examples are
+- * systemd during boot or git grep.
++ * In this comment we describe, firstly, the reasons why this fact
++ * holds, and, secondly, the next function, which implements the main
++ * steps needed to properly mark these queues so that they can then be
++ * treated in a different way.
+  *
+- * These services or applications benefit mostly from a high throughput:
+- * the quicker the requests of the activated queues are cumulatively served,
+- * the sooner the target job of these queues gets completed. As a consequence,
+- * weight-raising any of these queues, which also implies idling the device
+- * for it, is almost always counterproductive: in most cases it just lowers
+- * throughput.
++ * The above services or applications benefit mostly from a high
++ * throughput: the quicker the requests of the activated queues are
++ * cumulatively served, the sooner the target job of these queues gets
++ * completed. As a consequence, weight-raising any of these queues,
++ * which also implies idling the device for it, is almost always
++ * counterproductive. In most cases it just lowers throughput.
+  *
+- * On the other hand, a burst of activations may be also caused by the start
+- * of an application that does not consist in a lot of parallel I/O-bound
+- * threads. In fact, with a complex application, the burst may be just a
+- * consequence of the fact that several processes need to be executed to
+- * start-up the application. To start an application as quickly as possible,
+- * the best thing to do is to privilege the I/O related to the application
+- * with respect to all other I/O. Therefore, the best strategy to start as
+- * quickly as possible an application that causes a burst of activations is
+- * to weight-raise all the queues activated during the burst. This is the
++ * On the other hand, a burst of queue creations may be caused also by
++ * the start of an application that does not consist of a lot of
++ * parallel I/O-bound threads. In fact, with a complex application,
++ * several short processes may need to be executed to start-up the
++ * application. In this respect, to start an application as quickly as
++ * possible, the best thing to do is in any case to privilege the I/O
++ * related to the application with respect to all other
++ * I/O. Therefore, the best strategy to start as quickly as possible
++ * an application that causes a burst of queue creations is to
++ * weight-raise all the queues created during the burst. This is the
+  * exact opposite of the best strategy for the other type of bursts.
+  *
+- * In the end, to take the best action for each of the two cases, the two
+- * types of bursts need to be distinguished. Fortunately, this seems
+- * relatively easy to do, by looking at the sizes of the bursts. In
+- * particular, we found a threshold such that bursts with a larger size
+- * than that threshold are apparently caused only by services or commands
+- * such as systemd or git grep. For brevity, hereafter we call just 'large'
+- * these bursts. BFQ *does not* weight-raise queues whose activations occur
+- * in a large burst. In addition, for each of these queues BFQ performs or
+- * does not perform idling depending on which choice boosts the throughput
+- * most. The exact choice depends on the device and request pattern at
++ * In the end, to take the best action for each of the two cases, the
++ * two types of bursts need to be distinguished. Fortunately, this
++ * seems relatively easy, by looking at the sizes of the bursts. In
++ * particular, we found a threshold such that only bursts with a
++ * larger size than that threshold are apparently caused by
++ * services or commands such as systemd or git grep. For brevity,
++ * hereafter we call just 'large' these bursts. BFQ *does not*
++ * weight-raise queues whose creation occurs in a large burst. In
++ * addition, for each of these queues BFQ performs or does not perform
++ * idling depending on which choice boosts the throughput more. The
++ * exact choice depends on the device and request pattern at
+  * hand.
+  *
+- * Turning back to the next function, it implements all the steps needed
+- * to detect the occurrence of a large burst and to properly mark all the
+- * queues belonging to it (so that they can then be treated in a different
+- * way). This goal is achieved by maintaining a special "burst list" that
+- * holds, temporarily, the queues that belong to the burst in progress. The
+- * list is then used to mark these queues as belonging to a large burst if
+- * the burst does become large. The main steps are the following.
++ * Unfortunately, false positives may occur while an interactive task
++ * is starting (e.g., an application is being started). The
++ * consequence is that the queues associated with the task do not
++ * enjoy weight raising as expected. Fortunately these false positives
++ * are very rare. They typically occur if some service happens to
++ * start doing I/O exactly when the interactive task starts.
++ *
++ * Turning back to the next function, it implements all the steps
++ * needed to detect the occurrence of a large burst and to properly
++ * mark all the queues belonging to it (so that they can then be
++ * treated in a different way). This goal is achieved by maintaining a
++ * "burst list" that holds, temporarily, the queues that belong to the
++ * burst in progress. The list is then used to mark these queues as
++ * belonging to a large burst if the burst does become large. The main
++ * steps are the following.
+  *
+- * . when the very first queue is activated, the queue is inserted into the
++ * . when the very first queue is created, the queue is inserted into the
+  *   list (as it could be the first queue in a possible burst)
+  *
+  * . if the current burst has not yet become large, and a queue Q that does
+@@ -773,13 +799,13 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+  *
+  *     . the device enters a large-burst mode
+  *
+- * . if a queue Q that does not belong to the burst is activated while
++ * . if a queue Q that does not belong to the burst is created while
+  *   the device is in large-burst mode and shortly after the last time
+  *   at which a queue either entered the burst list or was marked as
+  *   belonging to the current large burst, then Q is immediately marked
+  *   as belonging to a large burst.
+  *
+- * . if a queue Q that does not belong to the burst is activated a while
++ * . if a queue Q that does not belong to the burst is created a while
+  *   later, i.e., not shortly after, than the last time at which a queue
+  *   either entered the burst list or was marked as belonging to the
+  *   current large burst, then the current burst is deemed as finished and:
+@@ -792,52 +818,44 @@ static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+  *          in a possible new burst (then the burst list contains just Q
+  *          after this step).
+  */
+-static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+-			     bool idle_for_long_time)
++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ {
+ 	/*
+-	 * If bfqq happened to be activated in a burst, but has been idle
+-	 * for at least as long as an interactive queue, then we assume
+-	 * that, in the overall I/O initiated in the burst, the I/O
+-	 * associated to bfqq is finished. So bfqq does not need to be
+-	 * treated as a queue belonging to a burst anymore. Accordingly,
+-	 * we reset bfqq's in_large_burst flag if set, and remove bfqq
+-	 * from the burst list if it's there. We do not decrement instead
+-	 * burst_size, because the fact that bfqq does not need to belong
+-	 * to the burst list any more does not invalidate the fact that
+-	 * bfqq may have been activated during the current burst.
+-	 */
+-	if (idle_for_long_time) {
+-		hlist_del_init(&bfqq->burst_list_node);
+-		bfq_clear_bfqq_in_large_burst(bfqq);
+-	}
+-
+-	/*
+ 	 * If bfqq is already in the burst list or is part of a large
+-	 * burst, then there is nothing else to do.
++	 * burst, or finally has just been split, then there is
++	 * nothing else to do.
+ 	 */
+ 	if (!hlist_unhashed(&bfqq->burst_list_node) ||
+-	    bfq_bfqq_in_large_burst(bfqq))
++	    bfq_bfqq_in_large_burst(bfqq) ||
++	    time_is_after_eq_jiffies(bfqq->split_time +
++				     msecs_to_jiffies(10)))
+ 		return;
+ 
+ 	/*
+-	 * If bfqq's activation happens late enough, then the current
+-	 * burst is finished, and related data structures must be reset.
++	 * If bfqq's creation happens late enough, or bfqq belongs to
++	 * a different group than the burst group, then the current
++	 * burst is finished, and related data structures must be
++	 * reset.
+ 	 *
+-	 * In this respect, consider the special case where bfqq is the very
+-	 * first queue being activated. In this case, last_ins_in_burst is
+-	 * not yet significant when we get here. But it is easy to verify
+-	 * that, whether or not the following condition is true, bfqq will
+-	 * end up being inserted into the burst list. In particular the
+-	 * list will happen to contain only bfqq. And this is exactly what
+-	 * has to happen, as bfqq may be the first queue in a possible
++	 * In this respect, consider the special case where bfqq is
++	 * the very first queue created after BFQ is selected for this
++	 * device. In this case, last_ins_in_burst and
++	 * burst_parent_entity are not yet significant when we get
++	 * here. But it is easy to verify that, whether or not the
++	 * following condition is true, bfqq will end up being
++	 * inserted into the burst list. In particular the list will
++	 * happen to contain only bfqq. And this is exactly what has
++	 * to happen, as bfqq may be the first queue of the first
+ 	 * burst.
+ 	 */
+ 	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
+-	    bfqd->bfq_burst_interval)) {
++	    bfqd->bfq_burst_interval) ||
++	    bfqq->entity.parent != bfqd->burst_parent_entity) {
+ 		bfqd->large_burst = false;
+ 		bfq_reset_burst_list(bfqd, bfqq);
+-		return;
++		bfq_log_bfqq(bfqd, bfqq,
++			"handle_burst: late activation or different group");
++		goto end;
+ 	}
+ 
+ 	/*
+@@ -846,8 +864,9 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	 * bfqq as belonging to this large burst immediately.
+ 	 */
+ 	if (bfqd->large_burst) {
++		bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
+ 		bfq_mark_bfqq_in_large_burst(bfqq);
+-		return;
++		goto end;
+ 	}
+ 
+ 	/*
+@@ -856,25 +875,492 @@ static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	 * queue. Then we add bfqq to the burst.
+ 	 */
+ 	bfq_add_to_burst(bfqd, bfqq);
++end:
++	/*
++	 * At this point, bfqq either has been added to the current
++	 * burst or has caused the current burst to terminate and a
++	 * possible new burst to start. In particular, in the second
++	 * case, bfqq has become the first queue in the possible new
++	 * burst.  In both cases last_ins_in_burst needs to be moved
++	 * forward.
++	 */
++	bfqd->last_ins_in_burst = jiffies;
++
++}
++
++static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++	return entity->budget - entity->service;
++}
++
++/*
++ * If enough samples have been computed, return the current max budget
++ * stored in bfqd, which is dynamically updated according to the
++ * estimated disk peak rate; otherwise return the default max budget
++ */
++static int bfq_max_budget(struct bfq_data *bfqd)
++{
++	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
++		return bfq_default_max_budget;
++	else
++		return bfqd->bfq_max_budget;
++}
++
++/*
++ * Return min budget, which is a fraction of the current or default
++ * max budget (trying with 1/32)
++ */
++static int bfq_min_budget(struct bfq_data *bfqd)
++{
++	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
++		return bfq_default_max_budget / 32;
++	else
++		return bfqd->bfq_max_budget / 32;
++}
++
++static void bfq_bfqq_expire(struct bfq_data *bfqd,
++			    struct bfq_queue *bfqq,
++			    bool compensate,
++			    enum bfqq_expiration reason);
++
++/*
++ * The next function, invoked after the input queue bfqq switches from
++ * idle to busy, updates the budget of bfqq. The function also tells
++ * whether the in-service queue should be expired, by returning
++ * true. The purpose of expiring the in-service queue is to give bfqq
++ * the chance to possibly preempt the in-service queue, and the reason
++ * for preempting the in-service queue is to achieve one of the two
++ * goals below.
++ *
++ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
++ * expired because it has remained idle. In particular, bfqq may have
++ * expired for one of the following two reasons:
++ *
++ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
++ *   did not make it to issue a new request before its last request
++ *   was served;
++ *
++ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
++ *   a new request before the expiration of the idling-time.
++ *
++ * Even if bfqq has expired for one of the above reasons, the process
++ * associated with the queue may be however issuing requests greedily,
++ * and thus be sensitive to the bandwidth it receives (bfqq may have
++ * remained idle for other reasons: CPU high load, bfqq not enjoying
++ * idling, I/O throttling somewhere in the path from the process to
++ * the I/O scheduler, ...). But if, after every expiration for one of
++ * the above two reasons, bfqq has to wait for the service of at least
++ * one full budget of another queue before being served again, then
++ * bfqq is likely to get a much lower bandwidth or resource time than
++ * its reserved ones. To address this issue, two countermeasures need
++ * to be taken.
++ *
++ * First, the budget and the timestamps of bfqq need to be updated in
++ * a special way on bfqq reactivation: they need to be updated as if
++ * bfqq did not remain idle and did not expire. In fact, if they are
++ * computed as if bfqq expired and remained idle until reactivation,
++ * then the process associated with bfqq is treated as if, instead of
++ * being greedy, it stopped issuing requests when bfqq remained idle,
++ * and restarts issuing requests only on this reactivation. In other
++ * words, the scheduler does not help the process recover the "service
++ * hole" between bfqq expiration and reactivation. As a consequence,
++ * the process receives a lower bandwidth than its reserved one. In
++ * contrast, to recover this hole, the budget must be updated as if
++ * bfqq was not expired at all before this reactivation, i.e., it must
++ * be set to the value of the remaining budget when bfqq was
++ * expired. Along the same line, timestamps need to be assigned the
++ * value they had the last time bfqq was selected for service, i.e.,
++ * before last expiration. Thus timestamps need to be back-shifted
++ * with respect to their normal computation (see [1] for more details
++ * on this tricky aspect).
++ *
++ * Secondly, to allow the process to recover the hole, the in-service
++ * queue must be expired too, to give bfqq the chance to preempt it
++ * immediately. In fact, if bfqq has to wait for a full budget of the
++ * in-service queue to be completed, then it may become impossible to
++ * let the process recover the hole, even if the back-shifted
++ * timestamps of bfqq are lower than those of the in-service queue. If
++ * this happens for most or all of the holes, then the process may not
++ * receive its reserved bandwidth. In this respect, it is worth noting
++ * that, being the service of outstanding requests unpreemptible, a
++ * little fraction of the holes may however be unrecoverable, thereby
++ * causing a little loss of bandwidth.
++ *
++ * The last important point is detecting whether bfqq does need this
++ * bandwidth recovery. In this respect, the next function deems the
++ * process associated with bfqq greedy, and thus allows it to recover
++ * the hole, if: 1) the process is waiting for the arrival of a new
++ * request (which implies that bfqq expired for one of the above two
++ * reasons), and 2) such a request has arrived soon. The first
++ * condition is controlled through the flag non_blocking_wait_rq,
++ * while the second through the flag arrived_in_time. If both
++ * conditions hold, then the function computes the budget in the
++ * above-described special way, and signals that the in-service queue
++ * should be expired. Timestamp back-shifting is done later in
++ * __bfq_activate_entity.
++ *
++ * 2. Reduce latency. Even if timestamps are not backshifted to let
++ * the process associated with bfqq recover a service hole, bfqq may
++ * however happen to have, after being (re)activated, a lower finish
++ * timestamp than the in-service queue.  That is, the next budget of
++ * bfqq may have to be completed before the one of the in-service
++ * queue. If this is the case, then preempting the in-service queue
++ * allows this goal to be achieved, apart from the unpreemptible,
++ * outstanding requests mentioned above.
++ *
++ * Unfortunately, regardless of which of the above two goals one wants
++ * to achieve, service trees need first to be updated to know whether
++ * the in-service queue must be preempted. To have service trees
++ * correctly updated, the in-service queue must be expired and
++ * rescheduled, and bfqq must be scheduled too. This is one of the
++ * most costly operations (in future versions, the scheduling
++ * mechanism may be re-designed in such a way to make it possible to
++ * know whether preemption is needed without needing to update service
++ * trees). In addition, queue preemptions almost always cause random
++ * I/O, and thus loss of throughput. Because of these facts, the next
++ * function adopts the following simple scheme to avoid both costly
++ * operations and too frequent preemptions: it requests the expiration
++ * of the in-service queue (unconditionally) only for queues that need
++ * to recover a hole, or that either are weight-raised or deserve to
++ * be weight-raised.
++ */
++static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
++						struct bfq_queue *bfqq,
++						bool arrived_in_time,
++						bool wr_or_deserves_wr)
++{
++	struct bfq_entity *entity = &bfqq->entity;
++
++	if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) {
++		/*
++		 * We do not clear the flag non_blocking_wait_rq here, as
++		 * the latter is used in bfq_activate_bfqq to signal
++		 * that timestamps need to be back-shifted (and is
++		 * cleared right after).
++		 */
++
++		/*
++		 * In next assignment we rely on that either
++		 * entity->service or entity->budget are not updated
++		 * on expiration if bfqq is empty (see
++		 * __bfq_bfqq_recalc_budget). Thus both quantities
++		 * remain unchanged after such an expiration, and the
++		 * following statement therefore assigns to
++		 * entity->budget the remaining budget on such an
++		 * expiration. For clarity, entity->service is not
++		 * updated on expiration in any case, and, in normal
++		 * operation, is reset only when bfqq is selected for
++		 * service (see bfq_get_next_queue).
++		 */
++		entity->budget = min_t(unsigned long,
++				       bfq_bfqq_budget_left(bfqq),
++				       bfqq->max_budget);
++
++		BUG_ON(entity->budget < 0);
++		return true;
++	}
++
++	entity->budget = max_t(unsigned long, bfqq->max_budget,
++			       bfq_serv_to_charge(bfqq->next_rq,bfqq));
++	BUG_ON(entity->budget < 0);
++
++	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
++	return wr_or_deserves_wr;
++}
++
++static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
++					     struct bfq_queue *bfqq,
++					     unsigned int old_wr_coeff,
++					     bool wr_or_deserves_wr,
++					     bool interactive,
++					     bool in_burst,
++					     bool soft_rt)
++{
++	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
++		/* start a weight-raising period */
++		bfqq->wr_coeff = bfqd->bfq_wr_coeff;
++		if (interactive) /* update wr duration */
++			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
++		else
++			bfqq->wr_cur_max_time =
++				bfqd->bfq_wr_rt_max_time;
++		/*
++		 * If needed, further reduce budget to make sure it is
++		 * close to bfqq's backlog, so as to reduce the
++		 * scheduling-error component due to a too large
++		 * budget. Do not care about throughput consequences,
++		 * but only about latency. Finally, do not assign a
++		 * too small budget either, to avoid increasing
++		 * latency by causing too frequent expirations.
++		 */
++		bfqq->entity.budget = min_t(unsigned long,
++					    bfqq->entity.budget,
++					    2 * bfq_min_budget(bfqd));
++
++		bfq_log_bfqq(bfqd, bfqq,
++			     "wrais starting at %lu, rais_max_time %u",
++			     jiffies,
++			     jiffies_to_msecs(bfqq->wr_cur_max_time));
++	} else if (old_wr_coeff > 1) {
++		if (interactive) /* update wr duration */
++			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
++		else if (in_burst) {
++			bfqq->wr_coeff = 1;
++			bfq_log_bfqq(bfqd, bfqq,
++				     "wrais ending at %lu, rais_max_time %u",
++				     jiffies,
++				     jiffies_to_msecs(bfqq->
++						      wr_cur_max_time));
++		} else if (time_before(
++				   bfqq->last_wr_start_finish +
++				   bfqq->wr_cur_max_time,
++				   jiffies +
++				   bfqd->bfq_wr_rt_max_time) &&
++			   soft_rt) {
++			/*
++			 * The remaining weight-raising time is lower
++			 * than bfqd->bfq_wr_rt_max_time, which means
++			 * that the application is enjoying weight
++			 * raising either because deemed soft-rt in
++			 * the near past, or because deemed interactive
++			 * a long ago.
++			 * In both cases, resetting now the current
++			 * remaining weight-raising time for the
++			 * application to the weight-raising duration
++			 * for soft rt applications would not cause any
++			 * latency increase for the application (as the
++			 * new duration would be higher than the
++			 * remaining time).
++			 *
++			 * In addition, the application is now meeting
++			 * the requirements for being deemed soft rt.
++			 * In the end we can correctly and safely
++			 * (re)charge the weight-raising duration for
++			 * the application with the weight-raising
++			 * duration for soft rt applications.
++			 *
++			 * In particular, doing this recharge now, i.e.,
++			 * before the weight-raising period for the
++			 * application finishes, reduces the probability
++			 * of the following negative scenario:
++			 * 1) the weight of a soft rt application is
++			 *    raised at startup (as for any newly
++			 *    created application),
++			 * 2) since the application is not interactive,
++			 *    at a certain time weight-raising is
++			 *    stopped for the application,
++			 * 3) at that time the application happens to
++			 *    still have pending requests, and hence
++			 *    is destined to not have a chance to be
++			 *    deemed soft rt before these requests are
++			 *    completed (see the comments to the
++			 *    function bfq_bfqq_softrt_next_start()
++			 *    for details on soft rt detection),
++			 * 4) these pending requests experience a high
++			 *    latency because the application is not
++			 *    weight-raised while they are pending.
++			 */
++			bfqq->last_wr_start_finish = jiffies;
++			bfqq->wr_cur_max_time =
++				bfqd->bfq_wr_rt_max_time;
++			bfq_log_bfqq(bfqd, bfqq,
++				     "switching to soft_rt wr, or "
++				     " just moving forward duration");
++		}
++	}
++}
++
++static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
++					struct bfq_queue *bfqq)
++{
++	return bfqq->dispatched == 0 &&
++		time_is_before_jiffies(
++			bfqq->budget_timeout +
++			bfqd->bfq_wr_min_idle_time);
++}
++
++static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
++					     struct bfq_queue *bfqq,
++					     int old_wr_coeff,
++					     struct request *rq,
++					     bool *interactive)
++{
++	bool soft_rt, in_burst,	wr_or_deserves_wr,
++		bfqq_wants_to_preempt,
++		idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
++		/*
++		 * See the comments on
++		 * bfq_bfqq_update_budg_for_activation for
++		 * details on the usage of the next variable.
++		 */
++		arrived_in_time = time_is_after_jiffies(
++			RQ_BIC(rq)->ttime.last_end_request +
++			bfqd->bfq_slice_idle * 3);
++
++	bfq_log_bfqq(bfqd, bfqq,
++		     "bfq_add_request non-busy: "
++		     "jiffies %lu, in_time %d, idle_long %d busyw %d "
++		     "wr_coeff %u",
++		     jiffies, arrived_in_time,
++		     idle_for_long_time,
++		     bfq_bfqq_non_blocking_wait_rq(bfqq),
++		     old_wr_coeff);
++
++	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
++
++	BUG_ON(bfqq == bfqd->in_service_queue);
++	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq,
++				 rq->cmd_flags);
++
++	/*
++	 * bfqq deserves to be weight-raised if:
++	 * - it is sync,
++	 * - it does not belong to a large burst,
++	 * - it has been idle for enough time or is soft real-time,
++	 * - is linked to a bfq_io_cq (it is not shared in any sense)
++	 */
++	in_burst = bfq_bfqq_in_large_burst(bfqq);
++	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
++		!in_burst &&
++		time_is_before_jiffies(bfqq->soft_rt_next_start);
++	*interactive =
++		!in_burst &&
++		idle_for_long_time;
++	wr_or_deserves_wr = bfqd->low_latency &&
++		(bfqq->wr_coeff > 1 ||
++		 (bfq_bfqq_sync(bfqq) &&
++		  bfqq->bic && (*interactive || soft_rt)));
++
++	bfq_log_bfqq(bfqd, bfqq,
++		     "bfq_add_request: "
++		     "in_burst %d, "
++		     "soft_rt %d (next %lu), inter %d, bic %p",
++		     bfq_bfqq_in_large_burst(bfqq), soft_rt,
++		     bfqq->soft_rt_next_start,
++		     *interactive,
++		     bfqq->bic);
++
++	/*
++	 * Using the last flag, update budget and check whether bfqq
++	 * may want to preempt the in-service queue.
++	 */
++	bfqq_wants_to_preempt =
++		bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
++						    arrived_in_time,
++						    wr_or_deserves_wr);
++
++	/*
++	 * If bfqq happened to be activated in a burst, but has been
++	 * idle for much more than an interactive queue, then we
++	 * assume that, in the overall I/O initiated in the burst, the
++	 * I/O associated with bfqq is finished. So bfqq does not need
++	 * to be treated as a queue belonging to a burst
++	 * anymore. Accordingly, we reset bfqq's in_large_burst flag
++	 * if set, and remove bfqq from the burst list if it's
++	 * there. We do not decrement burst_size, because the fact
++	 * that bfqq does not need to belong to the burst list any
++	 * more does not invalidate the fact that bfqq was created in
++	 * a burst.
++	 */
++	if (likely(!bfq_bfqq_just_created(bfqq)) &&
++	    idle_for_long_time &&
++	    time_is_before_jiffies(
++		    bfqq->budget_timeout +
++		    msecs_to_jiffies(10000))) {
++		hlist_del_init(&bfqq->burst_list_node);
++		bfq_clear_bfqq_in_large_burst(bfqq);
++	}
++
++	bfq_clear_bfqq_just_created(bfqq);
++
++	if (!bfq_bfqq_IO_bound(bfqq)) {
++		if (arrived_in_time) {
++			bfqq->requests_within_timer++;
++			if (bfqq->requests_within_timer >=
++			    bfqd->bfq_requests_within_timer)
++				bfq_mark_bfqq_IO_bound(bfqq);
++		} else
++			bfqq->requests_within_timer = 0;
++		bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
++			     bfqq->requests_within_timer);
++	}
++
++	if (bfqd->low_latency) {
++		if (unlikely(time_is_after_jiffies(bfqq->split_time)))
++			/* wraparound */
++			bfqq->split_time =
++				jiffies - bfqd->bfq_wr_min_idle_time - 1;
++
++		if (time_is_before_jiffies(bfqq->split_time +
++					   bfqd->bfq_wr_min_idle_time)) {
++			bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
++							 old_wr_coeff,
++							 wr_or_deserves_wr,
++							 *interactive,
++							 in_burst,
++							 soft_rt);
++
++			if (old_wr_coeff != bfqq->wr_coeff)
++				bfqq->entity.prio_changed = 1;
++		}
++	}
++
++	bfqq->last_idle_bklogged = jiffies;
++	bfqq->service_from_backlogged = 0;
++	bfq_clear_bfqq_softrt_update(bfqq);
++
++	bfq_add_bfqq_busy(bfqd, bfqq);
++
++	/*
++	 * Expire in-service queue only if preemption may be needed
++	 * for guarantees. In this respect, the function
++	 * next_queue_may_preempt just checks a simple, necessary
++	 * condition, and not a sufficient condition based on
++	 * timestamps. In fact, for the latter condition to be
++	 * evaluated, timestamps would need first to be updated, and
++	 * this operation is quite costly (see the comments on the
++	 * function bfq_bfqq_update_budg_for_activation).
++	 */
++	if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
++	    bfqd->in_service_queue->wr_coeff == 1 &&
++	    next_queue_may_preempt(bfqd)) {
++		struct bfq_queue *in_serv =
++			bfqd->in_service_queue;
++		BUG_ON(in_serv == bfqq);
++
++		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
++				false, BFQ_BFQQ_PREEMPTED);
++		BUG_ON(in_serv->entity.budget < 0);
++	}
+ }
+ 
+ static void bfq_add_request(struct request *rq)
+ {
+ 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
+-	struct bfq_entity *entity = &bfqq->entity;
+ 	struct bfq_data *bfqd = bfqq->bfqd;
+ 	struct request *next_rq, *prev;
+-	unsigned long old_wr_coeff = bfqq->wr_coeff;
++	unsigned int old_wr_coeff = bfqq->wr_coeff;
+ 	bool interactive = false;
+ 
+-	bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq));
++	bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
++		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
++
++	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
++		bfq_log_bfqq(bfqd, bfqq,
++			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
++			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
++			jiffies_to_msecs(bfqq->wr_cur_max_time),
++			bfqq->wr_coeff,
++			bfqq->entity.weight, bfqq->entity.orig_weight);
++
+ 	bfqq->queued[rq_is_sync(rq)]++;
+ 	bfqd->queued++;
+ 
+ 	elv_rb_add(&bfqq->sort_list, rq);
+ 
+ 	/*
+-	 * Check if this request is a better next-serve candidate.
++	 * Check if this request is a better next-to-serve candidate.
+ 	 */
+ 	prev = bfqq->next_rq;
+ 	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
+@@ -887,160 +1373,10 @@ static void bfq_add_request(struct request *rq)
+ 	if (prev != bfqq->next_rq)
+ 		bfq_pos_tree_add_move(bfqd, bfqq);
+ 
+-	if (!bfq_bfqq_busy(bfqq)) {
+-		bool soft_rt, coop_or_in_burst,
+-		     idle_for_long_time = time_is_before_jiffies(
+-						bfqq->budget_timeout +
+-						bfqd->bfq_wr_min_idle_time);
+-
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+-		bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq,
+-					 rq->cmd_flags);
+-#endif
+-		if (bfq_bfqq_sync(bfqq)) {
+-			bool already_in_burst =
+-			   !hlist_unhashed(&bfqq->burst_list_node) ||
+-			   bfq_bfqq_in_large_burst(bfqq);
+-			bfq_handle_burst(bfqd, bfqq, idle_for_long_time);
+-			/*
+-			 * If bfqq was not already in the current burst,
+-			 * then, at this point, bfqq either has been
+-			 * added to the current burst or has caused the
+-			 * current burst to terminate. In particular, in
+-			 * the second case, bfqq has become the first
+-			 * queue in a possible new burst.
+-			 * In both cases last_ins_in_burst needs to be
+-			 * moved forward.
+-			 */
+-			if (!already_in_burst)
+-				bfqd->last_ins_in_burst = jiffies;
+-		}
+-
+-		coop_or_in_burst = bfq_bfqq_in_large_burst(bfqq) ||
+-			bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh;
+-		soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
+-			!coop_or_in_burst &&
+-			time_is_before_jiffies(bfqq->soft_rt_next_start);
+-		interactive = !coop_or_in_burst && idle_for_long_time;
+-		entity->budget = max_t(unsigned long, bfqq->max_budget,
+-				       bfq_serv_to_charge(next_rq, bfqq));
+-
+-		if (!bfq_bfqq_IO_bound(bfqq)) {
+-			if (time_before(jiffies,
+-					RQ_BIC(rq)->ttime.last_end_request +
+-					bfqd->bfq_slice_idle)) {
+-				bfqq->requests_within_timer++;
+-				if (bfqq->requests_within_timer >=
+-				    bfqd->bfq_requests_within_timer)
+-					bfq_mark_bfqq_IO_bound(bfqq);
+-			} else
+-				bfqq->requests_within_timer = 0;
+-		}
+-
+-		if (!bfqd->low_latency)
+-			goto add_bfqq_busy;
+-
+-		if (bfq_bfqq_just_split(bfqq))
+-			goto set_prio_changed;
+-
+-		/*
+-		 * If the queue:
+-		 * - is not being boosted,
+-		 * - has been idle for enough time,
+-		 * - is not a sync queue or is linked to a bfq_io_cq (it is
+-		 *   shared "for its nature" or it is not shared and its
+-		 *   requests have not been redirected to a shared queue)
+-		 * start a weight-raising period.
+-		 */
+-		if (old_wr_coeff == 1 && (interactive || soft_rt) &&
+-		    (!bfq_bfqq_sync(bfqq) || bfqq->bic)) {
+-			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+-			if (interactive)
+-				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+-			else
+-				bfqq->wr_cur_max_time =
+-					bfqd->bfq_wr_rt_max_time;
+-			bfq_log_bfqq(bfqd, bfqq,
+-				     "wrais starting at %lu, rais_max_time %u",
+-				     jiffies,
+-				     jiffies_to_msecs(bfqq->wr_cur_max_time));
+-		} else if (old_wr_coeff > 1) {
+-			if (interactive)
+-				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+-			else if (coop_or_in_burst ||
+-				 (bfqq->wr_cur_max_time ==
+-				  bfqd->bfq_wr_rt_max_time &&
+-				  !soft_rt)) {
+-				bfqq->wr_coeff = 1;
+-				bfq_log_bfqq(bfqd, bfqq,
+-					"wrais ending at %lu, rais_max_time %u",
+-					jiffies,
+-					jiffies_to_msecs(bfqq->
+-						wr_cur_max_time));
+-			} else if (time_before(
+-					bfqq->last_wr_start_finish +
+-					bfqq->wr_cur_max_time,
+-					jiffies +
+-					bfqd->bfq_wr_rt_max_time) &&
+-				   soft_rt) {
+-				/*
+-				 *
+-				 * The remaining weight-raising time is lower
+-				 * than bfqd->bfq_wr_rt_max_time, which means
+-				 * that the application is enjoying weight
+-				 * raising either because deemed soft-rt in
+-				 * the near past, or because deemed interactive
+-				 * a long ago.
+-				 * In both cases, resetting now the current
+-				 * remaining weight-raising time for the
+-				 * application to the weight-raising duration
+-				 * for soft rt applications would not cause any
+-				 * latency increase for the application (as the
+-				 * new duration would be higher than the
+-				 * remaining time).
+-				 *
+-				 * In addition, the application is now meeting
+-				 * the requirements for being deemed soft rt.
+-				 * In the end we can correctly and safely
+-				 * (re)charge the weight-raising duration for
+-				 * the application with the weight-raising
+-				 * duration for soft rt applications.
+-				 *
+-				 * In particular, doing this recharge now, i.e.,
+-				 * before the weight-raising period for the
+-				 * application finishes, reduces the probability
+-				 * of the following negative scenario:
+-				 * 1) the weight of a soft rt application is
+-				 *    raised at startup (as for any newly
+-				 *    created application),
+-				 * 2) since the application is not interactive,
+-				 *    at a certain time weight-raising is
+-				 *    stopped for the application,
+-				 * 3) at that time the application happens to
+-				 *    still have pending requests, and hence
+-				 *    is destined to not have a chance to be
+-				 *    deemed soft rt before these requests are
+-				 *    completed (see the comments to the
+-				 *    function bfq_bfqq_softrt_next_start()
+-				 *    for details on soft rt detection),
+-				 * 4) these pending requests experience a high
+-				 *    latency because the application is not
+-				 *    weight-raised while they are pending.
+-				 */
+-				bfqq->last_wr_start_finish = jiffies;
+-				bfqq->wr_cur_max_time =
+-					bfqd->bfq_wr_rt_max_time;
+-			}
+-		}
+-set_prio_changed:
+-		if (old_wr_coeff != bfqq->wr_coeff)
+-			entity->prio_changed = 1;
+-add_bfqq_busy:
+-		bfqq->last_idle_bklogged = jiffies;
+-		bfqq->service_from_backlogged = 0;
+-		bfq_clear_bfqq_softrt_update(bfqq);
+-		bfq_add_bfqq_busy(bfqd, bfqq);
+-	} else {
++	if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
++		bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
++						 rq, &interactive);
++	else {
+ 		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
+ 		    time_is_before_jiffies(
+ 				bfqq->last_wr_start_finish +
+@@ -1049,16 +1385,43 @@ add_bfqq_busy:
+ 			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ 
+ 			bfqd->wr_busy_queues++;
+-			entity->prio_changed = 1;
++			bfqq->entity.prio_changed = 1;
+ 			bfq_log_bfqq(bfqd, bfqq,
+-			    "non-idle wrais starting at %lu, rais_max_time %u",
+-			    jiffies,
+-			    jiffies_to_msecs(bfqq->wr_cur_max_time));
++				     "non-idle wrais starting, "
++				     "wr_max_time %u wr_busy %d",
++				     jiffies_to_msecs(bfqq->wr_cur_max_time),
++				     bfqd->wr_busy_queues);
+ 		}
+ 		if (prev != bfqq->next_rq)
+ 			bfq_updated_next_req(bfqd, bfqq);
+ 	}
+ 
++	/*
++	 * Assign jiffies to last_wr_start_finish in the following
++	 * cases:
++	 *
++	 * . if bfqq is not going to be weight-raised, because, for
++	 *   non weight-raised queues, last_wr_start_finish stores the
++	 *   arrival time of the last request; as of now, this piece
++	 *   of information is used only for deciding whether to
++	 *   weight-raise async queues
++	 *
++	 * . if bfqq is not weight-raised, because, if bfqq is now
++	 *   switching to weight-raised, then last_wr_start_finish
++	 *   stores the time when weight-raising starts
++	 *
++	 * . if bfqq is interactive, because, regardless of whether
++	 *   bfqq is currently weight-raised, the weight-raising
++	 *   period must start or restart (this case is considered
++	 *   separately because it is not detected by the above
++	 *   conditions, if bfqq is already weight-raised)
++	 *
++	 * last_wr_start_finish has to be updated also if bfqq is soft
++	 * real-time, because the weight-raising period is constantly
++	 * restarted on idle-to-busy transitions for these queues, but
++	 * this is already done in bfq_bfqq_handle_idle_busy_switch if
++	 * needed.
++	 */
+ 	if (bfqd->low_latency &&
+ 		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
+ 		bfqq->last_wr_start_finish = jiffies;
+@@ -1106,6 +1469,9 @@ static void bfq_remove_request(struct request *rq)
+ 	struct bfq_data *bfqd = bfqq->bfqd;
+ 	const int sync = rq_is_sync(rq);
+ 
++	BUG_ON(bfqq->entity.service > bfqq->entity.budget &&
++	       bfqq == bfqd->in_service_queue);
++
+ 	if (bfqq->next_rq == rq) {
+ 		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
+ 		bfq_updated_next_req(bfqd, bfqq);
+@@ -1119,8 +1485,25 @@ static void bfq_remove_request(struct request *rq)
+ 	elv_rb_del(&bfqq->sort_list, rq);
+ 
+ 	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+-		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue)
++		BUG_ON(bfqq->entity.budget < 0);
++
++		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
+ 			bfq_del_bfqq_busy(bfqd, bfqq, 1);
++
++			/* bfqq emptied. In normal operation, when
++			 * bfqq is empty, bfqq->entity.service and
++			 * bfqq->entity.budget must contain,
++			 * respectively, the service received and the
++			 * budget used last time bfqq emptied. These
++			 * facts do not hold in this case, as at least
++			 * this last removal occurred while bfqq is
++			 * not in service. To avoid inconsistencies,
++			 * reset both bfqq->entity.service and
++			 * bfqq->entity.budget.
++			 */
++			bfqq->entity.budget = bfqq->entity.service = 0;
++		}
++
+ 		/*
+ 		 * Remove queue from request-position tree as it is empty.
+ 		 */
+@@ -1134,9 +1517,7 @@ static void bfq_remove_request(struct request *rq)
+ 		BUG_ON(bfqq->meta_pending == 0);
+ 		bfqq->meta_pending--;
+ 	}
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
+-#endif
+ }
+ 
+ static int bfq_merge(struct request_queue *q, struct request **req,
+@@ -1221,21 +1602,25 @@ static void bfq_merged_requests(struct request_queue *q, struct request *rq,
+ 		bfqq->next_rq = rq;
+ 
+ 	bfq_remove_request(next);
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
+-#endif
+ }
+ 
+ /* Must be called with bfqq != NULL */
+ static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
+ {
+ 	BUG_ON(!bfqq);
++
+ 	if (bfq_bfqq_busy(bfqq))
+ 		bfqq->bfqd->wr_busy_queues--;
+ 	bfqq->wr_coeff = 1;
+ 	bfqq->wr_cur_max_time = 0;
+-	/* Trigger a weight change on the next activation of the queue */
++	/*
++	 * Trigger a weight change on the next invocation of
++	 * __bfq_entity_update_weight_prio.
++	 */
+ 	bfqq->entity.prio_changed = 1;
++	bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
++		     bfqq->bfqd->wr_busy_queues);
+ }
+ 
+ static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+@@ -1278,7 +1663,7 @@ static int bfq_rq_close_to_sector(void *io_struct, bool request,
+ 				  sector_t sector)
+ {
+ 	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
+-	       BFQQ_SEEK_THR;
++	       BFQQ_CLOSE_THR;
+ }
+ 
+ static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
+@@ -1400,7 +1785,7 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+ 	 * throughput.
+ 	 */
+ 	bfqq->new_bfqq = new_bfqq;
+-	atomic_add(process_refs, &new_bfqq->ref);
++	new_bfqq->ref += process_refs;
+ 	return new_bfqq;
+ }
+ 
+@@ -1431,9 +1816,23 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
+ }
+ 
+ /*
+- * Attempt to schedule a merge of bfqq with the currently in-service queue
+- * or with a close queue among the scheduled queues.
+- * Return NULL if no merge was scheduled, a pointer to the shared bfq_queue
++ * If this function returns true, then bfqq cannot be merged. The idea
++ * is that true cooperation happens very early after processes start
++ * to do I/O. Usually, late cooperations are just accidental false
++ * positives. In case bfqq is weight-raised, such false positives
++ * would evidently degrade latency guarantees for bfqq.
++ */
++bool wr_from_too_long(struct bfq_queue *bfqq)
++{
++	return bfqq->wr_coeff > 1 &&
++		time_is_before_jiffies(bfqq->last_wr_start_finish +
++				       msecs_to_jiffies(100));
++}
++
++/*
++ * Attempt to schedule a merge of bfqq with the currently in-service
++ * queue or with a close queue among the scheduled queues.  Return
++ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
+  * structure otherwise.
+  *
+  * The OOM queue is not allowed to participate to cooperation: in fact, since
+@@ -1442,6 +1841,18 @@ static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
+  * handle merging with the OOM queue would be quite complex and expensive
+  * to maintain. Besides, in such a critical condition as an out of memory,
+  * the benefits of queue merging may be little relevant, or even negligible.
++ *
++ * Weight-raised queues can be merged only if their weight-raising
++ * period has just started. In fact cooperating processes are usually
++ * started together. Thus, with this filter we avoid false positives
++ * that would jeopardize low-latency guarantees.
++ *
++ * WARNING: queue merging may impair fairness among non-weight raised
++ * queues, for at least two reasons: 1) the original weight of a
++ * merged queue may change during the merged state, 2) even being the
++ * weight the same, a merged queue may be bloated with many more
++ * requests than the ones produced by its originally-associated
++ * process.
+  */
+ static struct bfq_queue *
+ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+@@ -1451,16 +1862,32 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 
+ 	if (bfqq->new_bfqq)
+ 		return bfqq->new_bfqq;
+-	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
++
++	if (io_struct && wr_from_too_long(bfqq) &&
++	    likely(bfqq != &bfqd->oom_bfqq))
++		bfq_log_bfqq(bfqd, bfqq,
++			     "would have looked for coop, but bfq%d wr",
++			bfqq->pid);
++
++	if (!io_struct ||
++	    wr_from_too_long(bfqq) ||
++	    unlikely(bfqq == &bfqd->oom_bfqq))
+ 		return NULL;
+-	/* If device has only one backlogged bfq_queue, don't search. */
++
++	/* If there is only one backlogged queue, don't search. */
+ 	if (bfqd->busy_queues == 1)
+ 		return NULL;
+ 
+ 	in_service_bfqq = bfqd->in_service_queue;
+ 
++	if (in_service_bfqq && in_service_bfqq != bfqq &&
++	    bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
++	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
++		bfq_log_bfqq(bfqd, bfqq,
++		"would have tried merge with in-service-queue, but wr");
++
+ 	if (!in_service_bfqq || in_service_bfqq == bfqq ||
+-	    !bfqd->in_service_bic ||
++	    !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
+ 	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
+ 		goto check_scheduled;
+ 
+@@ -1482,7 +1909,15 @@ check_scheduled:
+ 
+ 	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
+ 
+-	if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq) &&
++	if (new_bfqq && wr_from_too_long(new_bfqq) &&
++	    likely(new_bfqq != &bfqd->oom_bfqq) &&
++	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
++		bfq_log_bfqq(bfqd, bfqq,
++			     "would have merged with bfq%d, but wr",
++			     new_bfqq->pid);
++
++	if (new_bfqq && !wr_from_too_long(new_bfqq) &&
++	    likely(new_bfqq != &bfqd->oom_bfqq) &&
+ 	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
+ 		return bfq_setup_merge(bfqq, new_bfqq);
+ 
+@@ -1498,46 +1933,11 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
+ 	 */
+ 	if (!bfqq->bic)
+ 		return;
+-	if (bfqq->bic->wr_time_left)
+-		/*
+-		 * This is the queue of a just-started process, and would
+-		 * deserve weight raising: we set wr_time_left to the full
+-		 * weight-raising duration to trigger weight-raising when
+-		 * and if the queue is split and the first request of the
+-		 * queue is enqueued.
+-		 */
+-		bfqq->bic->wr_time_left = bfq_wr_duration(bfqq->bfqd);
+-	else if (bfqq->wr_coeff > 1) {
+-		unsigned long wr_duration =
+-			jiffies - bfqq->last_wr_start_finish;
+-		/*
+-		 * It may happen that a queue's weight raising period lasts
+-		 * longer than its wr_cur_max_time, as weight raising is
+-		 * handled only when a request is enqueued or dispatched (it
+-		 * does not use any timer). If the weight raising period is
+-		 * about to end, don't save it.
+-		 */
+-		if (bfqq->wr_cur_max_time <= wr_duration)
+-			bfqq->bic->wr_time_left = 0;
+-		else
+-			bfqq->bic->wr_time_left =
+-				bfqq->wr_cur_max_time - wr_duration;
+-		/*
+-		 * The bfq_queue is becoming shared or the requests of the
+-		 * process owning the queue are being redirected to a shared
+-		 * queue. Stop the weight raising period of the queue, as in
+-		 * both cases it should not be owned by an interactive or
+-		 * soft real-time application.
+-		 */
+-		bfq_bfqq_end_wr(bfqq);
+-	} else
+-		bfqq->bic->wr_time_left = 0;
++
+ 	bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
+ 	bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
+ 	bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
+ 	bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
+-	bfqq->bic->cooperations++;
+-	bfqq->bic->failed_cooperations = 0;
+ }
+ 
+ static void bfq_get_bic_reference(struct bfq_queue *bfqq)
+@@ -1562,6 +1962,40 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
+ 	if (bfq_bfqq_IO_bound(bfqq))
+ 		bfq_mark_bfqq_IO_bound(new_bfqq);
+ 	bfq_clear_bfqq_IO_bound(bfqq);
++
++	/*
++	 * If bfqq is weight-raised, then let new_bfqq inherit
++	 * weight-raising. To reduce false positives, neglect the case
++	 * where bfqq has just been created, but has not yet made it
++	 * to be weight-raised (which may happen because EQM may merge
++	 * bfqq even before bfq_add_request is executed for the first
++	 * time for bfqq). Handling this case would however be very
++	 * easy, thanks to the flag just_created.
++	 */
++	if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
++		new_bfqq->wr_coeff = bfqq->wr_coeff;
++		new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
++		new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
++		if (bfq_bfqq_busy(new_bfqq))
++		    bfqd->wr_busy_queues++;
++		new_bfqq->entity.prio_changed = 1;
++		bfq_log_bfqq(bfqd, new_bfqq,
++			     "wr starting after merge with %d, "
++			     "rais_max_time %u",
++			     bfqq->pid,
++			     jiffies_to_msecs(bfqq->wr_cur_max_time));
++	}
++
++	if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
++		bfqq->wr_coeff = 1;
++		bfqq->entity.prio_changed = 1;
++		if (bfq_bfqq_busy(bfqq))
++			bfqd->wr_busy_queues--;
++	}
++
++	bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
++		     bfqd->wr_busy_queues);
++
+ 	/*
+ 	 * Grab a reference to the bic, to prevent it from being destroyed
+ 	 * before being possibly touched by a bfq_split_bfqq().
+@@ -1588,18 +2022,6 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
+ 	bfq_put_queue(bfqq);
+ }
+ 
+-static void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq)
+-{
+-	struct bfq_io_cq *bic = bfqq->bic;
+-	struct bfq_data *bfqd = bfqq->bfqd;
+-
+-	if (bic && bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh) {
+-		bic->failed_cooperations++;
+-		if (bic->failed_cooperations >= bfqd->bfq_failed_cooperations)
+-			bic->cooperations = 0;
+-	}
+-}
+-
+ static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ 			   struct bio *bio)
+ {
+@@ -1637,30 +2059,86 @@ static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ 			 * to decide whether bio and rq can be merged.
+ 			 */
+ 			bfqq = new_bfqq;
+-		} else
+-			bfq_bfqq_increase_failed_cooperations(bfqq);
++		}
+ 	}
+ 
+ 	return bfqq == RQ_BFQQ(rq);
+ }
+ 
++/*
++ * Set the maximum time for the in-service queue to consume its
++ * budget. This prevents seeky processes from lowering the throughput.
++ * In practice, a time-slice service scheme is used with seeky
++ * processes.
++ */
++static void bfq_set_budget_timeout(struct bfq_data *bfqd,
++				   struct bfq_queue *bfqq)
++{
++	unsigned int timeout_coeff;
++	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
++		timeout_coeff = 1;
++	else
++		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
++
++	bfqd->last_budget_start = ktime_get();
++
++	bfqq->budget_timeout = jiffies +
++		bfqd->bfq_timeout * timeout_coeff;
++
++	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
++		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
++}
++
+ static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
+ 				       struct bfq_queue *bfqq)
+ {
+ 	if (bfqq) {
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
+-#endif
+ 		bfq_mark_bfqq_must_alloc(bfqq);
+-		bfq_mark_bfqq_budget_new(bfqq);
+ 		bfq_clear_bfqq_fifo_expire(bfqq);
+ 
+ 		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
+ 
++		BUG_ON(bfqq == bfqd->in_service_queue);
++		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
++
++		if (bfqq->wr_coeff > 1 &&
++		    bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
++			time_is_before_jiffies(bfqq->budget_timeout)) {
++			/*
++			 * For soft real-time queues, move the start
++			 * of the weight-raising period forward by the
++			 * time the queue has not received any
++			 * service. Otherwise, a relatively long
++			 * service delay is likely to cause the
++			 * weight-raising period of the queue to end,
++			 * because of the short duration of the
++			 * weight-raising period of a soft real-time
++			 * queue.  It is worth noting that this move
++			 * is not so dangerous for the other queues,
++			 * because soft real-time queues are not
++			 * greedy.
++			 *
++			 * To not add a further variable, we use the
++			 * overloaded field budget_timeout to
++			 * determine for how long the queue has not
++			 * received service, i.e., how much time has
++			 * elapsed since the queue expired. However,
++			 * this is a little imprecise, because
++			 * budget_timeout is set to jiffies if bfqq
++			 * not only expires, but also remains with no
++			 * request.
++			 */
++			bfqq->last_wr_start_finish += jiffies -
++				bfqq->budget_timeout;
++		}
++
++		bfq_set_budget_timeout(bfqd, bfqq);
+ 		bfq_log_bfqq(bfqd, bfqq,
+ 			     "set_in_service_queue, cur-budget = %d",
+ 			     bfqq->entity.budget);
+-	}
++	} else
++		bfq_log(bfqd, "set_in_service_queue: NULL");
+ 
+ 	bfqd->in_service_queue = bfqq;
+ }
+@@ -1676,31 +2154,6 @@ static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
+ 	return bfqq;
+ }
+ 
+-/*
+- * If enough samples have been computed, return the current max budget
+- * stored in bfqd, which is dynamically updated according to the
+- * estimated disk peak rate; otherwise return the default max budget
+- */
+-static int bfq_max_budget(struct bfq_data *bfqd)
+-{
+-	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
+-		return bfq_default_max_budget;
+-	else
+-		return bfqd->bfq_max_budget;
+-}
+-
+-/*
+- * Return min budget, which is a fraction of the current or default
+- * max budget (trying with 1/32)
+- */
+-static int bfq_min_budget(struct bfq_data *bfqd)
+-{
+-	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
+-		return bfq_default_max_budget / 32;
+-	else
+-		return bfqd->bfq_max_budget / 32;
+-}
+-
+ static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+ {
+ 	struct bfq_queue *bfqq = bfqd->in_service_queue;
+@@ -1723,64 +2176,36 @@ static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+ 	 *
+ 	 * To prevent processes with (partly) seeky workloads from
+ 	 * being too ill-treated, grant them a small fraction of the
+-	 * assigned budget before reducing the waiting time to
+-	 * BFQ_MIN_TT. This happened to help reduce latency.
+-	 */
+-	sl = bfqd->bfq_slice_idle;
+-	/*
+-	 * Unless the queue is being weight-raised or the scenario is
+-	 * asymmetric, grant only minimum idle time if the queue either
+-	 * has been seeky for long enough or has already proved to be
+-	 * constantly seeky.
+-	 */
+-	if (bfq_sample_valid(bfqq->seek_samples) &&
+-	    ((BFQQ_SEEKY(bfqq) && bfqq->entity.service >
+-				  bfq_max_budget(bfqq->bfqd) / 8) ||
+-	      bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1 &&
+-	    bfq_symmetric_scenario(bfqd))
+-		sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT));
+-	else if (bfqq->wr_coeff > 1)
+-		sl = sl * 3;
+-	bfqd->last_idling_start = ktime_get();
+-	mod_timer(&bfqd->idle_slice_timer, jiffies + sl);
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+-	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
+-#endif
+-	bfq_log(bfqd, "arm idle: %u/%u ms",
+-		jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle));
+-}
+-
+-/*
+- * Set the maximum time for the in-service queue to consume its
+- * budget. This prevents seeky processes from lowering the disk
+- * throughput (always guaranteed with a time slice scheme as in CFQ).
+- */
+-static void bfq_set_budget_timeout(struct bfq_data *bfqd)
+-{
+-	struct bfq_queue *bfqq = bfqd->in_service_queue;
+-	unsigned int timeout_coeff;
+-	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
+-		timeout_coeff = 1;
+-	else
+-		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
+-
+-	bfqd->last_budget_start = ktime_get();
+-
+-	bfq_clear_bfqq_budget_new(bfqq);
+-	bfqq->budget_timeout = jiffies +
+-		bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff;
++	 * assigned budget before reducing the waiting time to
++	 * BFQ_MIN_TT. This happened to help reduce latency.
++	 */
++	sl = bfqd->bfq_slice_idle;
++	/*
++	 * Unless the queue is being weight-raised or the scenario is
++	 * asymmetric, grant only minimum idle time if the queue
++	 * is seeky. A long idling is preserved for a weight-raised
++	 * queue, or, more in general, in an asymemtric scenario,
++	 * because a long idling is needed for guaranteeing to a queue
++	 * its reserved share of the throughput (in particular, it is
++	 * needed if the queue has a higher weight than some other
++	 * queue).
++	 */
++	if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
++	    bfq_symmetric_scenario(bfqd))
++		sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT));
+ 
+-	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
+-		jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] *
+-		timeout_coeff));
++	bfqd->last_idling_start = ktime_get();
++	mod_timer(&bfqd->idle_slice_timer, jiffies + sl);
++	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
++	bfq_log(bfqd, "arm idle: %u/%u ms",
++		jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle));
+ }
+ 
+ /*
+- * Move request from internal lists to the request queue dispatch list.
++ * Move request from internal lists to the dispatch list of the request queue
+  */
+ static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
+ {
+-	struct bfq_data *bfqd = q->elevator->elevator_data;
+ 	struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ 
+ 	/*
+@@ -1794,15 +2219,9 @@ static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
+ 	 * incrementing bfqq->dispatched.
+ 	 */
+ 	bfqq->dispatched++;
++
+ 	bfq_remove_request(rq);
+ 	elv_dispatch_sort(q, rq);
+-
+-	if (bfq_bfqq_sync(bfqq))
+-		bfqd->sync_flight++;
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+-	bfqg_stats_update_dispatch(bfqq_group(bfqq), blk_rq_bytes(rq),
+-				   rq->cmd_flags);
+-#endif
+ }
+ 
+ /*
+@@ -1822,18 +2241,12 @@ static struct request *bfq_check_fifo(struct bfq_queue *bfqq)
+ 
+ 	rq = rq_entry_fifo(bfqq->fifo.next);
+ 
+-	if (time_before(jiffies, rq->fifo_time))
++	if (time_is_after_jiffies(rq->fifo_time))
+ 		return NULL;
+ 
+ 	return rq;
+ }
+ 
+-static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
+-{
+-	struct bfq_entity *entity = &bfqq->entity;
+-	return entity->budget - entity->service;
+-}
+-
+ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ {
+ 	BUG_ON(bfqq != bfqd->in_service_queue);
+@@ -1850,12 +2263,15 @@ static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		bfq_mark_bfqq_split_coop(bfqq);
+ 
+ 	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+-		/*
+-		 * Overloading budget_timeout field to store the time
+-		 * at which the queue remains with no backlog; used by
+-		 * the weight-raising mechanism.
+-		 */
+-		bfqq->budget_timeout = jiffies;
++		if (bfqq->dispatched == 0)
++			/*
++			 * Overloading budget_timeout field to store
++			 * the time at which the queue remains with no
++			 * backlog and no outstanding request; used by
++			 * the weight-raising mechanism.
++			 */
++			bfqq->budget_timeout = jiffies;
++
+ 		bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ 	} else {
+ 		bfq_activate_bfqq(bfqd, bfqq);
+@@ -1882,10 +2298,19 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ 	struct request *next_rq;
+ 	int budget, min_budget;
+ 
+-	budget = bfqq->max_budget;
++	BUG_ON(bfqq != bfqd->in_service_queue);
++
+ 	min_budget = bfq_min_budget(bfqd);
+ 
+-	BUG_ON(bfqq != bfqd->in_service_queue);
++	if (bfqq->wr_coeff == 1)
++		budget = bfqq->max_budget;
++	else /*
++	      * Use a constant, low budget for weight-raised queues,
++	      * to help achieve a low latency. Keep it slightly higher
++	      * than the minimum possible budget, to cause a little
++	      * bit fewer expirations.
++	      */
++		budget = 2 * min_budget;
+ 
+ 	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
+ 		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
+@@ -1894,7 +2319,7 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ 	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
+ 		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
+ 
+-	if (bfq_bfqq_sync(bfqq)) {
++	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
+ 		switch (reason) {
+ 		/*
+ 		 * Caveat: in all the following cases we trade latency
+@@ -1936,14 +2361,10 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ 			break;
+ 		case BFQ_BFQQ_BUDGET_TIMEOUT:
+ 			/*
+-			 * We double the budget here because: 1) it
+-			 * gives the chance to boost the throughput if
+-			 * this is not a seeky process (which may have
+-			 * bumped into this timeout because of, e.g.,
+-			 * ZBR), 2) together with charge_full_budget
+-			 * it helps give seeky processes higher
+-			 * timestamps, and hence be served less
+-			 * frequently.
++			 * We double the budget here because it gives
++			 * the chance to boost the throughput if this
++			 * is not a seeky process (and has bumped into
++			 * this timeout because of, e.g., ZBR).
+ 			 */
+ 			budget = min(budget * 2, bfqd->bfq_max_budget);
+ 			break;
+@@ -1960,17 +2381,49 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ 			budget = min(budget * 4, bfqd->bfq_max_budget);
+ 			break;
+ 		case BFQ_BFQQ_NO_MORE_REQUESTS:
+-		       /*
+-			* Leave the budget unchanged.
+-			*/
++			/*
++			 * For queues that expire for this reason, it
++			 * is particularly important to keep the
++			 * budget close to the actual service they
++			 * need. Doing so reduces the timestamp
++			 * misalignment problem described in the
++			 * comments in the body of
++			 * __bfq_activate_entity. In fact, suppose
++			 * that a queue systematically expires for
++			 * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
++			 * new request in time to enjoy timestamp
++			 * back-shifting. The larger the budget of the
++			 * queue is with respect to the service the
++			 * queue actually requests in each service
++			 * slot, the more times the queue can be
++			 * reactivated with the same virtual finish
++			 * time. It follows that, even if this finish
++			 * time is pushed to the system virtual time
++			 * to reduce the consequent timestamp
++			 * misalignment, the queue unjustly enjoys for
++			 * many re-activations a lower finish time
++			 * than all newly activated queues.
++			 *
++			 * The service needed by bfqq is measured
++			 * quite precisely by bfqq->entity.service.
++			 * Since bfqq does not enjoy device idling,
++			 * bfqq->entity.service is equal to the number
++			 * of sectors that the process associated with
++			 * bfqq requested to read/write before waiting
++			 * for request completions, or blocking for
++			 * other reasons.
++			 */
++			budget = max_t(int, bfqq->entity.service, min_budget);
++			break;
+ 		default:
+ 			return;
+ 		}
+-	} else
++	} else if (!bfq_bfqq_sync(bfqq))
+ 		/*
+-		 * Async queues get always the maximum possible budget
+-		 * (their ability to dispatch is limited by
+-		 * @bfqd->bfq_max_budget_async_rq).
++		 * Async queues get always the maximum possible
++		 * budget, as for them we do not care about latency
++		 * (in addition, their ability to dispatch is limited
++		 * by the charging factor).
+ 		 */
+ 		budget = bfqd->bfq_max_budget;
+ 
+@@ -1981,65 +2434,105 @@ static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ 		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
+ 
+ 	/*
+-	 * Make sure that we have enough budget for the next request.
+-	 * Since the finish time of the bfqq must be kept in sync with
+-	 * the budget, be sure to call __bfq_bfqq_expire() after the
++	 * If there is still backlog, then assign a new budget, making
++	 * sure that it is large enough for the next request.  Since
++	 * the finish time of bfqq must be kept in sync with the
++	 * budget, be sure to call __bfq_bfqq_expire() *after* this
+ 	 * update.
++	 *
++	 * If there is no backlog, then no need to update the budget;
++	 * it will be updated on the arrival of a new request.
+ 	 */
+ 	next_rq = bfqq->next_rq;
+-	if (next_rq)
++	if (next_rq) {
++		BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
++		       reason == BFQ_BFQQ_NO_MORE_REQUESTS);
+ 		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
+ 					    bfq_serv_to_charge(next_rq, bfqq));
+-	else
+-		bfqq->entity.budget = bfqq->max_budget;
++		BUG_ON(!bfq_bfqq_busy(bfqq));
++		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
++	}
+ 
+ 	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
+ 			next_rq ? blk_rq_sectors(next_rq) : 0,
+ 			bfqq->entity.budget);
+ }
+ 
+-static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout)
++static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
+ {
+-	unsigned long max_budget;
+-
+ 	/*
+ 	 * The max_budget calculated when autotuning is equal to the
+-	 * amount of sectors transfered in timeout_sync at the
++	 * amount of sectors transfered in timeout at the
+ 	 * estimated peak rate.
+ 	 */
+-	max_budget = (unsigned long)(peak_rate * 1000 *
+-				     timeout >> BFQ_RATE_SHIFT);
+-
+-	return max_budget;
++	return bfqd->peak_rate * 1000 * jiffies_to_msecs(bfqd->bfq_timeout) >>
++		BFQ_RATE_SHIFT;
+ }
+ 
+ /*
+- * In addition to updating the peak rate, checks whether the process
+- * is "slow", and returns 1 if so. This slow flag is used, in addition
+- * to the budget timeout, to reduce the amount of service provided to
+- * seeky processes, and hence reduce their chances to lower the
+- * throughput. See the code for more details.
++ * Update the read peak rate (quantity used for auto-tuning) as a
++ * function of the rate at which bfqq has been served, and check
++ * whether the process associated with bfqq is "slow". Return true if
++ * the process is slow. The slow flag is used, in addition to the
++ * budget timeout, to reduce the amount of service provided to seeky
++ * processes, and hence reduce their chances to lower the
++ * throughput. More details in the body of the function.
++ *
++ * An important observation is in order: with devices with internal
++ * queues, it is hard if ever possible to know when and for how long
++ * an I/O request is processed by the device (apart from the trivial
++ * I/O pattern where a new request is dispatched only after the
++ * previous one has been completed). This makes it hard to evaluate
++ * the real rate at which the I/O requests of each bfq_queue are
++ * served.  In fact, for an I/O scheduler like BFQ, serving a
++ * bfq_queue means just dispatching its requests during its service
++ * slot, i.e., until the budget of the queue is exhausted, or the
++ * queue remains idle, or, finally, a timeout fires. But, during the
++ * service slot of a bfq_queue, the device may be still processing
++ * requests of bfq_queues served in previous service slots. On the
++ * opposite end, the requests of the in-service bfq_queue may be
++ * completed after the service slot of the queue finishes. Anyway,
++ * unless more sophisticated solutions are used (where possible), the
++ * sum of the sizes of the requests dispatched during the service slot
++ * of a bfq_queue is probably the only approximation available for
++ * the service received by the bfq_queue during its service slot. And,
++ * as written above, this sum is the quantity used in this function to
++ * evaluate the peak rate.
+  */
+ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+-				 bool compensate, enum bfqq_expiration reason)
++				 bool compensate, enum bfqq_expiration reason,
++				 unsigned long *delta_ms)
+ {
+-	u64 bw, usecs, expected, timeout;
+-	ktime_t delta;
++	u64 bw, bwdiv10, delta_usecs, delta_ms_tmp;
++	ktime_t delta_ktime;
+ 	int update = 0;
++	bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
+ 
+-	if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq))
++	if (!bfq_bfqq_sync(bfqq))
+ 		return false;
+ 
+ 	if (compensate)
+-		delta = bfqd->last_idling_start;
++		delta_ktime = bfqd->last_idling_start;
+ 	else
+-		delta = ktime_get();
+-	delta = ktime_sub(delta, bfqd->last_budget_start);
+-	usecs = ktime_to_us(delta);
++		delta_ktime = ktime_get();
++	delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
++	delta_usecs = ktime_to_us(delta_ktime);
+ 
+ 	/* Don't trust short/unrealistic values. */
+-	if (usecs < 100 || usecs >= LONG_MAX)
+-		return false;
++	if (delta_usecs < 1000 || delta_usecs >= LONG_MAX) {
++		if (blk_queue_nonrot(bfqd->queue))
++			*delta_ms = BFQ_MIN_TT; /* give same worst-case
++						   guarantees as
++						   idling for seeky
++						*/
++		else /* Charge at least one seek */
++			*delta_ms = jiffies_to_msecs(bfq_slice_idle);
++		return slow;
++	}
++
++	delta_ms_tmp = delta_usecs;
++	do_div(delta_ms_tmp, 1000);
++	*delta_ms = delta_ms_tmp;
+ 
+ 	/*
+ 	 * Calculate the bandwidth for the last slice.  We use a 64 bit
+@@ -2048,32 +2541,51 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	 * and to avoid overflows.
+ 	 */
+ 	bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT;
+-	do_div(bw, (unsigned long)usecs);
+-
+-	timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
++	do_div(bw, (unsigned long)delta_usecs);
+ 
++	bfq_log(bfqd, "measured bw = %llu sects/sec",
++		(1000000*bw)>>BFQ_RATE_SHIFT);
+ 	/*
+ 	 * Use only long (> 20ms) intervals to filter out spikes for
+ 	 * the peak rate estimation.
+ 	 */
+-	if (usecs > 20000) {
++	if (delta_usecs > 20000) {
++		bool fully_sequential = bfqq->seek_history == 0;
++		/*
++		 * Soft real-time queues are not good candidates for
++		 * evaluating bw, as they are likely to be slow even
++		 * if sequential.
++		 */
++		bool non_soft_rt = bfqq->wr_coeff == 1 ||
++			bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time;
++		bool consumed_large_budget =
++			reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
++			bfqq->entity.budget >= bfqd->bfq_max_budget * 2 / 3;
++		bool served_for_long_time =
++			reason == BFQ_BFQQ_BUDGET_TIMEOUT ||
++			consumed_large_budget;
++
++		BUG_ON(bfqq->seek_history == 0 &&
++		       hweight32(bfqq->seek_history) != 0);
++
+ 		if (bw > bfqd->peak_rate ||
+-		   (!BFQQ_SEEKY(bfqq) &&
+-		    reason == BFQ_BFQQ_BUDGET_TIMEOUT)) {
+-			bfq_log(bfqd, "measured bw =%llu", bw);
++		    (bfq_bfqq_sync(bfqq) && fully_sequential && non_soft_rt &&
++		     served_for_long_time)) {
+ 			/*
+ 			 * To smooth oscillations use a low-pass filter with
+-			 * alpha=7/8, i.e.,
+-			 * new_rate = (7/8) * old_rate + (1/8) * bw
++			 * alpha=9/10, i.e.,
++			 * new_rate = (9/10) * old_rate + (1/10) * bw
+ 			 */
+-			do_div(bw, 8);
+-			if (bw == 0)
+-				return 0;
+-			bfqd->peak_rate *= 7;
+-			do_div(bfqd->peak_rate, 8);
+-			bfqd->peak_rate += bw;
++			bwdiv10 = bw;
++			do_div(bwdiv10, 10);
++			if (bwdiv10 == 0)
++				return false; /* bw too low to be used */
++			bfqd->peak_rate *= 9;
++			do_div(bfqd->peak_rate, 10);
++			bfqd->peak_rate += bwdiv10;
+ 			update = 1;
+-			bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate);
++			bfq_log(bfqd, "new peak_rate = %llu sects/sec",
++				(1000000*bfqd->peak_rate)>>BFQ_RATE_SHIFT);
+ 		}
+ 
+ 		update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1;
+@@ -2086,9 +2598,8 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 			int dev_type = blk_queue_nonrot(bfqd->queue);
+ 			if (bfqd->bfq_user_max_budget == 0) {
+ 				bfqd->bfq_max_budget =
+-					bfq_calc_max_budget(bfqd->peak_rate,
+-							    timeout);
+-				bfq_log(bfqd, "new max_budget=%d",
++					bfq_calc_max_budget(bfqd);
++				bfq_log(bfqd, "new max_budget = %d",
+ 					bfqd->bfq_max_budget);
+ 			}
+ 			if (bfqd->device_speed == BFQ_BFQD_FAST &&
+@@ -2102,38 +2613,35 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 				bfqd->RT_prod = R_fast[dev_type] *
+ 						T_fast[dev_type];
+ 			}
++			bfq_log(bfqd, "dev_speed_class = %d (%d sects/sec), "
++				"thresh %d setcs/sec",
++				bfqd->device_speed,
++				bfqd->device_speed == BFQ_BFQD_FAST ?
++				(1000000*R_fast[dev_type])>>BFQ_RATE_SHIFT :
++				(1000000*R_slow[dev_type])>>BFQ_RATE_SHIFT,
++				(1000000*device_speed_thresh[dev_type])>>
++				BFQ_RATE_SHIFT);
+ 		}
++		/*
++		 * Caveat: processes doing IO in the slower disk zones
++		 * tend to be slow(er) even if not seeky. In this
++		 * respect, the estimated peak rate is likely to be an
++		 * average over the disk surface. Accordingly, to not
++		 * be too harsh with unlucky processes, a process is
++		 * deemed slow only if its bw has been lower than half
++		 * of the estimated peak rate.
++		 */
++		slow = bw < bfqd->peak_rate / 2;
+ 	}
+ 
+-	/*
+-	 * If the process has been served for a too short time
+-	 * interval to let its possible sequential accesses prevail on
+-	 * the initial seek time needed to move the disk head on the
+-	 * first sector it requested, then give the process a chance
+-	 * and for the moment return false.
+-	 */
+-	if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8)
+-		return false;
+-
+-	/*
+-	 * A process is considered ``slow'' (i.e., seeky, so that we
+-	 * cannot treat it fairly in the service domain, as it would
+-	 * slow down too much the other processes) if, when a slice
+-	 * ends for whatever reason, it has received service at a
+-	 * rate that would not be high enough to complete the budget
+-	 * before the budget timeout expiration.
+-	 */
+-	expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT;
++	bfq_log_bfqq(bfqd, bfqq,
++		     "update_peak_rate: bw %llu sect/s, peak rate %llu, "
++		     "slow %d",
++		     (1000000*bw)>>BFQ_RATE_SHIFT,
++		     (1000000*bfqd->peak_rate)>>BFQ_RATE_SHIFT,
++		     bw < bfqd->peak_rate / 2);
+ 
+-	/*
+-	 * Caveat: processes doing IO in the slower disk zones will
+-	 * tend to be slow(er) even if not seeky. And the estimated
+-	 * peak rate will actually be an average over the disk
+-	 * surface. Hence, to not be too harsh with unlucky processes,
+-	 * we keep a budget/3 margin of safety before declaring a
+-	 * process slow.
+-	 */
+-	return expected > (4 * bfqq->entity.budget) / 3;
++	return slow;
+ }
+ 
+ /*
+@@ -2191,6 +2699,15 @@ static bool bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
+ 						struct bfq_queue *bfqq)
+ {
++	bfq_log_bfqq(bfqd, bfqq,
++		     "softrt_next_start: service_blkg %lu "
++		     "soft_rate %u sects/sec"
++		     "interval %u",
++		     bfqq->service_from_backlogged,
++		     bfqd->bfq_wr_max_softrt_rate,
++		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
++				      bfqd->bfq_wr_max_softrt_rate));
++
+ 	return max(bfqq->last_idle_bklogged +
+ 		   HZ * bfqq->service_from_backlogged /
+ 		   bfqd->bfq_wr_max_softrt_rate,
+@@ -2198,13 +2715,21 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
+ }
+ 
+ /*
+- * Return the largest-possible time instant such that, for as long as possible,
+- * the current time will be lower than this time instant according to the macro
+- * time_is_before_jiffies().
++ * Return the farthest future time instant according to jiffies
++ * macros.
++ */
++static unsigned long bfq_greatest_from_now(void)
++{
++	return jiffies + MAX_JIFFY_OFFSET;
++}
++
++/*
++ * Return the farthest past time instant according to jiffies
++ * macros.
+  */
+-static unsigned long bfq_infinity_from_now(unsigned long now)
++static unsigned long bfq_smallest_from_now(void)
+ {
+-	return now + ULONG_MAX / 2;
++	return jiffies - MAX_JIFFY_OFFSET;
+ }
+ 
+ /**
+@@ -2214,28 +2739,24 @@ static unsigned long bfq_infinity_from_now(unsigned long now)
+  * @compensate: if true, compensate for the time spent idling.
+  * @reason: the reason causing the expiration.
+  *
++ * If the process associated with bfqq does slow I/O (e.g., because it
++ * issues random requests), we charge bfqq with the time it has been
++ * in service instead of the service it has received (see
++ * bfq_bfqq_charge_time for details on how this goal is achieved). As
++ * a consequence, bfqq will typically get higher timestamps upon
++ * reactivation, and hence it will be rescheduled as if it had
++ * received more service than what it has actually received. In the
++ * end, bfqq receives less service in proportion to how slowly its
++ * associated process consumes its budgets (and hence how seriously it
++ * tends to lower the throughput). In addition, this time-charging
++ * strategy guarantees time fairness among slow processes. In
++ * contrast, if the process associated with bfqq is not slow, we
++ * charge bfqq exactly with the service it has received.
+  *
+- * If the process associated to the queue is slow (i.e., seeky), or in
+- * case of budget timeout, or, finally, if it is async, we
+- * artificially charge it an entire budget (independently of the
+- * actual service it received). As a consequence, the queue will get
+- * higher timestamps than the correct ones upon reactivation, and
+- * hence it will be rescheduled as if it had received more service
+- * than what it actually received. In the end, this class of processes
+- * will receive less service in proportion to how slowly they consume
+- * their budgets (and hence how seriously they tend to lower the
+- * throughput).
+- *
+- * In contrast, when a queue expires because it has been idling for
+- * too much or because it exhausted its budget, we do not touch the
+- * amount of service it has received. Hence when the queue will be
+- * reactivated and its timestamps updated, the latter will be in sync
+- * with the actual service received by the queue until expiration.
+- *
+- * Charging a full budget to the first type of queues and the exact
+- * service to the others has the effect of using the WF2Q+ policy to
+- * schedule the former on a timeslice basis, without violating the
+- * service domain guarantees of the latter.
++ * Charging time to the first type of queues and the exact service to
++ * the other has the effect of using the WF2Q+ policy to schedule the
++ * former on a timeslice basis, without violating service domain
++ * guarantees among the latter.
+  */
+ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ 			    struct bfq_queue *bfqq,
+@@ -2243,40 +2764,51 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ 			    enum bfqq_expiration reason)
+ {
+ 	bool slow;
++	unsigned long delta = 0;
++	struct bfq_entity *entity = &bfqq->entity;
++
+ 	BUG_ON(bfqq != bfqd->in_service_queue);
+ 
+ 	/*
+-	 * Update disk peak rate for autotuning and check whether the
++	 * Update device peak rate for autotuning and check whether the
+ 	 * process is slow (see bfq_update_peak_rate).
+ 	 */
+-	slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason);
++	slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason, &delta);
+ 
+ 	/*
+-	 * As above explained, 'punish' slow (i.e., seeky), timed-out
+-	 * and async queues, to favor sequential sync workloads.
+-	 *
+-	 * Processes doing I/O in the slower disk zones will tend to be
+-	 * slow(er) even if not seeky. Hence, since the estimated peak
+-	 * rate is actually an average over the disk surface, these
+-	 * processes may timeout just for bad luck. To avoid punishing
+-	 * them we do not charge a full budget to a process that
+-	 * succeeded in consuming at least 2/3 of its budget.
++	 * Increase service_from_backlogged before next statement,
++	 * because the possible next invocation of
++	 * bfq_bfqq_charge_time would likely inflate
++	 * entity->service. In contrast, service_from_backlogged must
++	 * contain real service, to enable the soft real-time
++	 * heuristic to correctly compute the bandwidth consumed by
++	 * bfqq.
+ 	 */
+-	if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+-		     bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3))
+-		bfq_bfqq_charge_full_budget(bfqq);
++	bfqq->service_from_backlogged += entity->service;
+ 
+-	bfqq->service_from_backlogged += bfqq->entity.service;
+-
+-	if (BFQQ_SEEKY(bfqq) && reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+-	    !bfq_bfqq_constantly_seeky(bfqq)) {
+-		bfq_mark_bfqq_constantly_seeky(bfqq);
+-		if (!blk_queue_nonrot(bfqd->queue))
+-			bfqd->const_seeky_busy_in_flight_queues++;
+-	}
++	/*
++	 * As above explained, charge slow (typically seeky) and
++	 * timed-out queues with the time and not the service
++	 * received, to favor sequential workloads.
++	 *
++	 * Processes doing I/O in the slower disk zones will tend to
++	 * be slow(er) even if not seeky. Therefore, since the
++	 * estimated peak rate is actually an average over the disk
++	 * surface, these processes may timeout just for bad luck. To
++	 * avoid punishing them, do not charge time to processes that
++	 * succeeded in consuming at least 2/3 of their budget. This
++	 * allows BFQ to preserve enough elasticity to still perform
++	 * bandwidth, and not time, distribution with little unlucky
++	 * or quasi-sequential processes.
++	 */
++	if (bfqq->wr_coeff == 1 &&
++	    (slow ||
++	     (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
++	      bfq_bfqq_budget_left(bfqq) >=  entity->budget / 3)))
++		bfq_bfqq_charge_time(bfqd, bfqq, delta);
+ 
+ 	if (reason == BFQ_BFQQ_TOO_IDLE &&
+-	    bfqq->entity.service <= 2 * bfqq->entity.budget / 10 )
++	    entity->service <= 2 * entity->budget / 10 )
+ 		bfq_clear_bfqq_IO_bound(bfqq);
+ 
+ 	if (bfqd->low_latency && bfqq->wr_coeff == 1)
+@@ -2285,19 +2817,23 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ 	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
+ 	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ 		/*
+-		 * If we get here, and there are no outstanding requests,
+-		 * then the request pattern is isochronous (see the comments
+-		 * to the function bfq_bfqq_softrt_next_start()). Hence we
+-		 * can compute soft_rt_next_start. If, instead, the queue
+-		 * still has outstanding requests, then we have to wait
+-		 * for the completion of all the outstanding requests to
++		 * If we get here, and there are no outstanding
++		 * requests, then the request pattern is isochronous
++		 * (see the comments on the function
++		 * bfq_bfqq_softrt_next_start()). Thus we can compute
++		 * soft_rt_next_start. If, instead, the queue still
++		 * has outstanding requests, then we have to wait for
++		 * the completion of all the outstanding requests to
+ 		 * discover whether the request pattern is actually
+ 		 * isochronous.
+ 		 */
+-		if (bfqq->dispatched == 0)
++		BUG_ON(bfqd->busy_queues < 1);
++		if (bfqq->dispatched == 0) {
+ 			bfqq->soft_rt_next_start =
+ 				bfq_bfqq_softrt_next_start(bfqd, bfqq);
+-		else {
++			bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
++				     bfqq->soft_rt_next_start);
++		} else {
+ 			/*
+ 			 * The application is still waiting for the
+ 			 * completion of one or more requests:
+@@ -2314,7 +2850,7 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ 			 *    happened to be in the past.
+ 			 */
+ 			bfqq->soft_rt_next_start =
+-				bfq_infinity_from_now(jiffies);
++				bfq_greatest_from_now();
+ 			/*
+ 			 * Schedule an update of soft_rt_next_start to when
+ 			 * the task may be discovered to be isochronous.
+@@ -2324,8 +2860,9 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ 	}
+ 
+ 	bfq_log_bfqq(bfqd, bfqq,
+-		"expire (%d, slow %d, num_disp %d, idle_win %d)", reason,
+-		slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq));
++		"expire (%d, slow %d, num_disp %d, idle_win %d, weight %d)",
++		     reason, slow, bfqq->dispatched,
++		     bfq_bfqq_idle_window(bfqq), entity->weight);
+ 
+ 	/*
+ 	 * Increase, decrease or leave budget unchanged according to
+@@ -2333,6 +2870,14 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ 	 */
+ 	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
+ 	__bfq_bfqq_expire(bfqd, bfqq);
++
++	BUG_ON(!bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
++		!bfq_class_idle(bfqq));
++
++	if (!bfq_bfqq_busy(bfqq) &&
++	    reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
++	    reason != BFQ_BFQQ_BUDGET_EXHAUSTED)
++		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
+ }
+ 
+ /*
+@@ -2342,20 +2887,17 @@ static void bfq_bfqq_expire(struct bfq_data *bfqd,
+  */
+ static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
+ {
+-	if (bfq_bfqq_budget_new(bfqq) ||
+-	    time_before(jiffies, bfqq->budget_timeout))
+-		return false;
+-	return true;
++	return time_is_before_eq_jiffies(bfqq->budget_timeout);
+ }
+ 
+ /*
+- * If we expire a queue that is waiting for the arrival of a new
+- * request, we may prevent the fictitious timestamp back-shifting that
+- * allows the guarantees of the queue to be preserved (see [1] for
+- * this tricky aspect). Hence we return true only if this condition
+- * does not hold, or if the queue is slow enough to deserve only to be
+- * kicked off for preserving a high throughput.
+-*/
++ * If we expire a queue that is actively waiting (i.e., with the
++ * device idled) for the arrival of a new request, then we may incur
++ * the timestamp misalignment problem described in the body of the
++ * function __bfq_activate_entity. Hence we return true only if this
++ * condition does not hold, or if the queue is slow enough to deserve
++ * only to be kicked off for preserving a high throughput.
++ */
+ static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
+ {
+ 	bfq_log_bfqq(bfqq->bfqd, bfqq,
+@@ -2397,10 +2939,12 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ {
+ 	struct bfq_data *bfqd = bfqq->bfqd;
+ 	bool idling_boosts_thr, idling_boosts_thr_without_issues,
+-		all_queues_seeky, on_hdd_and_not_all_queues_seeky,
+ 		idling_needed_for_service_guarantees,
+ 		asymmetric_scenario;
+ 
++	if (bfqd->strict_guarantees)
++		return true;
++
+ 	/*
+ 	 * The next variable takes into account the cases where idling
+ 	 * boosts the throughput.
+@@ -2422,7 +2966,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ 	 */
+ 	idling_boosts_thr = !bfqd->hw_tag ||
+ 		(!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
+-		 bfq_bfqq_idle_window(bfqq)) ;
++		 bfq_bfqq_idle_window(bfqq));
+ 
+ 	/*
+ 	 * The value of the next variable,
+@@ -2463,74 +3007,27 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ 		bfqd->wr_busy_queues == 0;
+ 
+ 	/*
+-	 * There are then two cases where idling must be performed not
++	 * There is then a case where idling must be performed not
+ 	 * for throughput concerns, but to preserve service
+-	 * guarantees. In the description of these cases, we say, for
+-	 * short, that a queue is sequential/random if the process
+-	 * associated to the queue issues sequential/random requests
+-	 * (in the second case the queue may be tagged as seeky or
+-	 * even constantly_seeky).
+-	 *
+-	 * To introduce the first case, we note that, since
+-	 * bfq_bfqq_idle_window(bfqq) is false if the device is
+-	 * NCQ-capable and bfqq is random (see
+-	 * bfq_update_idle_window()), then, from the above two
+-	 * assignments it follows that
+-	 * idling_boosts_thr_without_issues is false if the device is
+-	 * NCQ-capable and bfqq is random. Therefore, for this case,
+-	 * device idling would never be allowed if we used just
+-	 * idling_boosts_thr_without_issues to decide whether to allow
+-	 * it. And, beneficially, this would imply that throughput
+-	 * would always be boosted also with random I/O on NCQ-capable
+-	 * HDDs.
+-	 *
+-	 * But we must be careful on this point, to avoid an unfair
+-	 * treatment for bfqq. In fact, because of the same above
+-	 * assignments, idling_boosts_thr_without_issues is, on the
+-	 * other hand, true if 1) the device is an HDD and bfqq is
+-	 * sequential, and 2) there are no busy weight-raised
+-	 * queues. As a consequence, if we used just
+-	 * idling_boosts_thr_without_issues to decide whether to idle
+-	 * the device, then with an HDD we might easily bump into a
+-	 * scenario where queues that are sequential and I/O-bound
+-	 * would enjoy idling, whereas random queues would not. The
+-	 * latter might then get a low share of the device throughput,
+-	 * simply because the former would get many requests served
+-	 * after being set as in service, while the latter would not.
++	 * guarantees.
+ 	 *
+-	 * To address this issue, we start by setting to true a
+-	 * sentinel variable, on_hdd_and_not_all_queues_seeky, if the
+-	 * device is rotational and not all queues with pending or
+-	 * in-flight requests are constantly seeky (i.e., there are
+-	 * active sequential queues, and bfqq might then be mistreated
+-	 * if it does not enjoy idling because it is random).
+-	 */
+-	all_queues_seeky = bfq_bfqq_constantly_seeky(bfqq) &&
+-			   bfqd->busy_in_flight_queues ==
+-			   bfqd->const_seeky_busy_in_flight_queues;
+-
+-	on_hdd_and_not_all_queues_seeky =
+-		!blk_queue_nonrot(bfqd->queue) && !all_queues_seeky;
+-
+-	/*
+-	 * To introduce the second case where idling needs to be
+-	 * performed to preserve service guarantees, we can note that
+-	 * allowing the drive to enqueue more than one request at a
+-	 * time, and hence delegating de facto final scheduling
+-	 * decisions to the drive's internal scheduler, causes loss of
+-	 * control on the actual request service order. In particular,
+-	 * the critical situation is when requests from different
+-	 * processes happens to be present, at the same time, in the
+-	 * internal queue(s) of the drive. In such a situation, the
+-	 * drive, by deciding the service order of the
+-	 * internally-queued requests, does determine also the actual
+-	 * throughput distribution among these processes. But the
+-	 * drive typically has no notion or concern about per-process
+-	 * throughput distribution, and makes its decisions only on a
+-	 * per-request basis. Therefore, the service distribution
+-	 * enforced by the drive's internal scheduler is likely to
+-	 * coincide with the desired device-throughput distribution
+-	 * only in a completely symmetric scenario where:
++	 * To introduce this case, we can note that allowing the drive
++	 * to enqueue more than one request at a time, and hence
++	 * delegating de facto final scheduling decisions to the
++	 * drive's internal scheduler, entails loss of control on the
++	 * actual request service order. In particular, the critical
++	 * situation is when requests from different processes happen
++	 * to be present, at the same time, in the internal queue(s)
++	 * of the drive. In such a situation, the drive, by deciding
++	 * the service order of the internally-queued requests, does
++	 * determine also the actual throughput distribution among
++	 * these processes. But the drive typically has no notion or
++	 * concern about per-process throughput distribution, and
++	 * makes its decisions only on a per-request basis. Therefore,
++	 * the service distribution enforced by the drive's internal
++	 * scheduler is likely to coincide with the desired
++	 * device-throughput distribution only in a completely
++	 * symmetric scenario where:
+ 	 * (i)  each of these processes must get the same throughput as
+ 	 *      the others;
+ 	 * (ii) all these processes have the same I/O pattern
+@@ -2552,26 +3049,53 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ 	 * words, only if sub-condition (i) holds, then idling is
+ 	 * allowed, and the device tends to be prevented from queueing
+ 	 * many requests, possibly of several processes. The reason
+-	 * for not controlling also sub-condition (ii) is that, first,
+-	 * in the case of an HDD, the asymmetry in terms of types of
+-	 * I/O patterns is already taken in to account in the above
+-	 * sentinel variable
+-	 * on_hdd_and_not_all_queues_seeky. Secondly, in the case of a
+-	 * flash-based device, we prefer however to privilege
+-	 * throughput (and idling lowers throughput for this type of
+-	 * devices), for the following reasons:
+-	 * 1) differently from HDDs, the service time of random
+-	 *    requests is not orders of magnitudes lower than the service
+-	 *    time of sequential requests; thus, even if processes doing
+-	 *    sequential I/O get a preferential treatment with respect to
+-	 *    others doing random I/O, the consequences are not as
+-	 *    dramatic as with HDDs;
+-	 * 2) if a process doing random I/O does need strong
+-	 *    throughput guarantees, it is hopefully already being
+-	 *    weight-raised, or the user is likely to have assigned it a
+-	 *    higher weight than the other processes (and thus
+-	 *    sub-condition (i) is likely to be false, which triggers
+-	 *    idling).
++	 * for not controlling also sub-condition (ii) is that we
++	 * exploit preemption to preserve guarantees in case of
++	 * symmetric scenarios, even if (ii) does not hold, as
++	 * explained in the next two paragraphs.
++	 *
++	 * Even if a queue, say Q, is expired when it remains idle, Q
++	 * can still preempt the new in-service queue if the next
++	 * request of Q arrives soon (see the comments on
++	 * bfq_bfqq_update_budg_for_activation). If all queues and
++	 * groups have the same weight, this form of preemption,
++	 * combined with the hole-recovery heuristic described in the
++	 * comments on function bfq_bfqq_update_budg_for_activation,
++	 * are enough to preserve a correct bandwidth distribution in
++	 * the mid term, even without idling. In fact, even if not
++	 * idling allows the internal queues of the device to contain
++	 * many requests, and thus to reorder requests, we can rather
++	 * safely assume that the internal scheduler still preserves a
++	 * minimum of mid-term fairness. The motivation for using
++	 * preemption instead of idling is that, by not idling,
++	 * service guarantees are preserved without minimally
++	 * sacrificing throughput. In other words, both a high
++	 * throughput and its desired distribution are obtained.
++	 *
++	 * More precisely, this preemption-based, idleless approach
++	 * provides fairness in terms of IOPS, and not sectors per
++	 * second. This can be seen with a simple example. Suppose
++	 * that there are two queues with the same weight, but that
++	 * the first queue receives requests of 8 sectors, while the
++	 * second queue receives requests of 1024 sectors. In
++	 * addition, suppose that each of the two queues contains at
++	 * most one request at a time, which implies that each queue
++	 * always remains idle after it is served. Finally, after
++	 * remaining idle, each queue receives very quickly a new
++	 * request. It follows that the two queues are served
++	 * alternatively, preempting each other if needed. This
++	 * implies that, although both queues have the same weight,
++	 * the queue with large requests receives a service that is
++	 * 1024/8 times as high as the service received by the other
++	 * queue.
++	 *
++	 * On the other hand, device idling is performed, and thus
++	 * pure sector-domain guarantees are provided, for the
++	 * following queues, which are likely to need stronger
++	 * throughput guarantees: weight-raised queues, and queues
++	 * with a higher weight than other queues. When such queues
++	 * are active, sub-condition (i) is false, which triggers
++	 * device idling.
+ 	 *
+ 	 * According to the above considerations, the next variable is
+ 	 * true (only) if sub-condition (i) holds. To compute the
+@@ -2579,7 +3103,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ 	 * the function bfq_symmetric_scenario(), but also check
+ 	 * whether bfqq is being weight-raised, because
+ 	 * bfq_symmetric_scenario() does not take into account also
+-	 * weight-raised queues (see comments to
++	 * weight-raised queues (see comments on
+ 	 * bfq_weights_tree_add()).
+ 	 *
+ 	 * As a side note, it is worth considering that the above
+@@ -2601,17 +3125,16 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ 	 * bfqq. Such a case is when bfqq became active in a burst of
+ 	 * queue activations. Queues that became active during a large
+ 	 * burst benefit only from throughput, as discussed in the
+-	 * comments to bfq_handle_burst. Thus, if bfqq became active
++	 * comments on bfq_handle_burst. Thus, if bfqq became active
+ 	 * in a burst and not idling the device maximizes throughput,
+ 	 * then the device must no be idled, because not idling the
+ 	 * device provides bfqq and all other queues in the burst with
+-	 * maximum benefit. Combining this and the two cases above, we
+-	 * can now establish when idling is actually needed to
+-	 * preserve service guarantees.
++	 * maximum benefit. Combining this and the above case, we can
++	 * now establish when idling is actually needed to preserve
++	 * service guarantees.
+ 	 */
+ 	idling_needed_for_service_guarantees =
+-		(on_hdd_and_not_all_queues_seeky || asymmetric_scenario) &&
+-		!bfq_bfqq_in_large_burst(bfqq);
++		asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
+ 
+ 	/*
+ 	 * We have now all the components we need to compute the return
+@@ -2621,6 +3144,14 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+ 	 * 2) idling either boosts the throughput (without issues), or
+ 	 *    is necessary to preserve service guarantees.
+ 	 */
++	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d "
++		     "wr_busy %d boosts %d IO-bound %d guar %d",
++		     bfq_bfqq_sync(bfqq), idling_boosts_thr,
++		     bfqd->wr_busy_queues,
++		     idling_boosts_thr_without_issues,
++		     bfq_bfqq_IO_bound(bfqq),
++		     idling_needed_for_service_guarantees);
++
+ 	return bfq_bfqq_sync(bfqq) &&
+ 		(idling_boosts_thr_without_issues ||
+ 		 idling_needed_for_service_guarantees);
+@@ -2632,7 +3163,7 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+  * 1) the queue must remain in service and cannot be expired, and
+  * 2) the device must be idled to wait for the possible arrival of a new
+  *    request for the queue.
+- * See the comments to the function bfq_bfqq_may_idle for the reasons
++ * See the comments on the function bfq_bfqq_may_idle for the reasons
+  * why performing device idling is the best choice to boost the throughput
+  * and preserve service guarantees when bfq_bfqq_may_idle itself
+  * returns true.
+@@ -2698,9 +3229,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
+ 				 */
+ 				bfq_clear_bfqq_wait_request(bfqq);
+ 				del_timer(&bfqd->idle_slice_timer);
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 				bfqg_stats_update_idle_time(bfqq_group(bfqq));
+-#endif
+ 			}
+ 			goto keep_queue;
+ 		}
+@@ -2745,14 +3274,11 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
+ 
+ 		/*
+-		 * If the queue was activated in a burst, or
+-		 * too much time has elapsed from the beginning
+-		 * of this weight-raising period, or the queue has
+-		 * exceeded the acceptable number of cooperations,
+-		 * then end weight raising.
++		 * If the queue was activated in a burst, or too much
++		 * time has elapsed from the beginning of this
++		 * weight-raising period, then end weight raising.
+ 		 */
+ 		if (bfq_bfqq_in_large_burst(bfqq) ||
+-		    bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh ||
+ 		    time_is_before_jiffies(bfqq->last_wr_start_finish +
+ 					   bfqq->wr_cur_max_time)) {
+ 			bfqq->last_wr_start_finish = jiffies;
+@@ -2814,10 +3340,25 @@ static int bfq_dispatch_request(struct bfq_data *bfqd,
+ 		goto expire;
+ 	}
+ 
++	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+ 	/* Finally, insert request into driver dispatch list. */
+ 	bfq_bfqq_served(bfqq, service_to_charge);
++
++	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
++
+ 	bfq_dispatch_insert(bfqd->queue, rq);
+ 
++	/*
++	 * If weight raising has to terminate for bfqq, then next
++	 * function causes an immediate update of bfqq's weight,
++	 * without waiting for next activation. As a consequence, on
++	 * expiration, bfqq will be timestamped as if has never been
++	 * weight-raised during this service slot, even if it has
++	 * received part or even most of the service as a
++	 * weight-raised queue. This inflates bfqq's timestamps, which
++	 * is beneficial, as bfqq is then more willing to leave the
++	 * device immediately to possible other weight-raised queues.
++	 */
+ 	bfq_update_wr_data(bfqd, bfqq);
+ 
+ 	bfq_log_bfqq(bfqd, bfqq,
+@@ -2833,9 +3374,7 @@ static int bfq_dispatch_request(struct bfq_data *bfqd,
+ 		bfqd->in_service_bic = RQ_BIC(rq);
+ 	}
+ 
+-	if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) &&
+-	    dispatched >= bfqd->bfq_max_budget_async_rq) ||
+-	    bfq_class_idle(bfqq)))
++	if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
+ 		goto expire;
+ 
+ 	return dispatched;
+@@ -2881,8 +3420,8 @@ static int bfq_forced_dispatch(struct bfq_data *bfqd)
+ 		st = bfq_entity_service_tree(&bfqq->entity);
+ 
+ 		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
+-		bfqq->max_budget = bfq_max_budget(bfqd);
+ 
++		bfqq->max_budget = bfq_max_budget(bfqd);
+ 		bfq_forget_idle(st);
+ 	}
+ 
+@@ -2895,9 +3434,9 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
+ {
+ 	struct bfq_data *bfqd = q->elevator->elevator_data;
+ 	struct bfq_queue *bfqq;
+-	int max_dispatch;
+ 
+ 	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
++
+ 	if (bfqd->busy_queues == 0)
+ 		return 0;
+ 
+@@ -2908,21 +3447,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
+ 	if (!bfqq)
+ 		return 0;
+ 
+-	if (bfq_class_idle(bfqq))
+-		max_dispatch = 1;
+-
+-	if (!bfq_bfqq_sync(bfqq))
+-		max_dispatch = bfqd->bfq_max_budget_async_rq;
+-
+-	if (!bfq_bfqq_sync(bfqq) && bfqq->dispatched >= max_dispatch) {
+-		if (bfqd->busy_queues > 1)
+-			return 0;
+-		if (bfqq->dispatched >= 4 * max_dispatch)
+-			return 0;
+-	}
+-
+-	if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq))
+-		return 0;
++	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+ 
+ 	bfq_clear_bfqq_wait_request(bfqq);
+ 	BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+@@ -2933,6 +3458,7 @@ static int bfq_dispatch_requests(struct request_queue *q, int force)
+ 	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
+ 			bfq_bfqq_sync(bfqq) ? "sync" : "async");
+ 
++	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
+ 	return 1;
+ }
+ 
+@@ -2949,11 +3475,11 @@ static void bfq_put_queue(struct bfq_queue *bfqq)
+ 	struct bfq_group *bfqg = bfqq_group(bfqq);
+ #endif
+ 
+-	BUG_ON(atomic_read(&bfqq->ref) <= 0);
++	BUG_ON(bfqq->ref <= 0);
+ 
+-	bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq,
+-		     atomic_read(&bfqq->ref));
+-	if (!atomic_dec_and_test(&bfqq->ref))
++	bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
++	bfqq->ref--;
++	if (bfqq->ref)
+ 		return;
+ 
+ 	BUG_ON(rb_first(&bfqq->sort_list));
+@@ -3007,8 +3533,7 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 		bfq_schedule_dispatch(bfqd);
+ 	}
+ 
+-	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq,
+-		     atomic_read(&bfqq->ref));
++	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
+ 
+ 	bfq_put_cooperator(bfqq);
+ 
+@@ -3019,26 +3544,7 @@ static void bfq_init_icq(struct io_cq *icq)
+ {
+ 	struct bfq_io_cq *bic = icq_to_bic(icq);
+ 
+-	bic->ttime.last_end_request = jiffies;
+-	/*
+-	 * A newly created bic indicates that the process has just
+-	 * started doing I/O, and is probably mapping into memory its
+-	 * executable and libraries: it definitely needs weight raising.
+-	 * There is however the possibility that the process performs,
+-	 * for a while, I/O close to some other process. EQM intercepts
+-	 * this behavior and may merge the queue corresponding to the
+-	 * process  with some other queue, BEFORE the weight of the queue
+-	 * is raised. Merged queues are not weight-raised (they are assumed
+-	 * to belong to processes that benefit only from high throughput).
+-	 * If the merge is basically the consequence of an accident, then
+-	 * the queue will be split soon and will get back its old weight.
+-	 * It is then important to write down somewhere that this queue
+-	 * does need weight raising, even if it did not make it to get its
+-	 * weight raised before being merged. To this purpose, we overload
+-	 * the field raising_time_left and assign 1 to it, to mark the queue
+-	 * as needing weight raising.
+-	 */
+-	bic->wr_time_left = 1;
++	bic->ttime.last_end_request = bfq_smallest_from_now();
+ }
+ 
+ static void bfq_exit_icq(struct io_cq *icq)
+@@ -3046,21 +3552,21 @@ static void bfq_exit_icq(struct io_cq *icq)
+ 	struct bfq_io_cq *bic = icq_to_bic(icq);
+ 	struct bfq_data *bfqd = bic_to_bfqd(bic);
+ 
+-	if (bic->bfqq[BLK_RW_ASYNC]) {
+-		bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_ASYNC]);
+-		bic->bfqq[BLK_RW_ASYNC] = NULL;
++	if (bic_to_bfqq(bic, false)) {
++		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
++		bic_set_bfqq(bic, NULL, false);
+ 	}
+ 
+-	if (bic->bfqq[BLK_RW_SYNC]) {
++	if (bic_to_bfqq(bic, true)) {
+ 		/*
+ 		 * If the bic is using a shared queue, put the reference
+ 		 * taken on the io_context when the bic started using a
+ 		 * shared bfq_queue.
+ 		 */
+-		if (bfq_bfqq_coop(bic->bfqq[BLK_RW_SYNC]))
++		if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
+ 			put_io_context(icq->ioc);
+-		bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]);
+-		bic->bfqq[BLK_RW_SYNC] = NULL;
++		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
++		bic_set_bfqq(bic, NULL, true);
+ 	}
+ }
+ 
+@@ -3068,7 +3574,8 @@ static void bfq_exit_icq(struct io_cq *icq)
+  * Update the entity prio values; note that the new values will not
+  * be used until the next (re)activation.
+  */
+-static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
++static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
++				     struct bfq_io_cq *bic)
+ {
+ 	struct task_struct *tsk = current;
+ 	int ioprio_class;
+@@ -3100,7 +3607,7 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *b
+ 		break;
+ 	}
+ 
+-	if (bfqq->new_ioprio < 0 || bfqq->new_ioprio >= IOPRIO_BE_NR) {
++	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
+ 		printk(KERN_CRIT "bfq_set_next_ioprio_data: new_ioprio %d\n",
+ 				 bfqq->new_ioprio);
+ 		BUG();
+@@ -3108,45 +3615,40 @@ static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *b
+ 
+ 	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
+ 	bfqq->entity.prio_changed = 1;
++	bfq_log_bfqq(bfqq->bfqd, bfqq,
++		     "set_next_ioprio_data: bic_class %d prio %d class %d",
++		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
+ }
+ 
+ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
+ {
+-	struct bfq_data *bfqd;
+-	struct bfq_queue *bfqq, *new_bfqq;
++	struct bfq_data *bfqd = bic_to_bfqd(bic);
++	struct bfq_queue *bfqq;
+ 	unsigned long uninitialized_var(flags);
+ 	int ioprio = bic->icq.ioc->ioprio;
+ 
+-	bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data),
+-				   &flags);
+ 	/*
+ 	 * This condition may trigger on a newly created bic, be sure to
+ 	 * drop the lock before returning.
+ 	 */
+ 	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
+-		goto out;
++		return;
+ 
+ 	bic->ioprio = ioprio;
+ 
+-	bfqq = bic->bfqq[BLK_RW_ASYNC];
++	bfqq = bic_to_bfqq(bic, false);
+ 	if (bfqq) {
+-		new_bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic,
+-					 GFP_ATOMIC);
+-		if (new_bfqq) {
+-			bic->bfqq[BLK_RW_ASYNC] = new_bfqq;
+-			bfq_log_bfqq(bfqd, bfqq,
+-				     "check_ioprio_change: bfqq %p %d",
+-				     bfqq, atomic_read(&bfqq->ref));
+-			bfq_put_queue(bfqq);
+-		}
++		bfq_put_queue(bfqq);
++		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
++		bic_set_bfqq(bic, bfqq, false);
++		bfq_log_bfqq(bfqd, bfqq,
++			     "check_ioprio_change: bfqq %p %d",
++			     bfqq, bfqq->ref);
+ 	}
+ 
+-	bfqq = bic->bfqq[BLK_RW_SYNC];
++	bfqq = bic_to_bfqq(bic, true);
+ 	if (bfqq)
+ 		bfq_set_next_ioprio_data(bfqq, bic);
+-
+-out:
+-	bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+ 
+ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+@@ -3155,8 +3657,9 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	RB_CLEAR_NODE(&bfqq->entity.rb_node);
+ 	INIT_LIST_HEAD(&bfqq->fifo);
+ 	INIT_HLIST_NODE(&bfqq->burst_list_node);
++	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
+ 
+-	atomic_set(&bfqq->ref, 0);
++	bfqq->ref = 0;
+ 	bfqq->bfqd = bfqd;
+ 
+ 	if (bic)
+@@ -3166,6 +3669,7 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 		if (!bfq_class_idle(bfqq))
+ 			bfq_mark_bfqq_idle_window(bfqq);
+ 		bfq_mark_bfqq_sync(bfqq);
++		bfq_mark_bfqq_just_created(bfqq);
+ 	} else
+ 		bfq_clear_bfqq_sync(bfqq);
+ 	bfq_mark_bfqq_IO_bound(bfqq);
+@@ -3175,72 +3679,17 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	bfqq->pid = pid;
+ 
+ 	bfqq->wr_coeff = 1;
+-	bfqq->last_wr_start_finish = 0;
++	bfqq->last_wr_start_finish = bfq_smallest_from_now();
++	bfqq->budget_timeout = bfq_smallest_from_now();
++	bfqq->split_time = bfq_smallest_from_now();
+ 	/*
+ 	 * Set to the value for which bfqq will not be deemed as
+ 	 * soft rt when it becomes backlogged.
+ 	 */
+-	bfqq->soft_rt_next_start = bfq_infinity_from_now(jiffies);
+-}
+-
+-static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd,
+-					      struct bio *bio, int is_sync,
+-					      struct bfq_io_cq *bic,
+-					      gfp_t gfp_mask)
+-{
+-	struct bfq_group *bfqg;
+-	struct bfq_queue *bfqq, *new_bfqq = NULL;
+-	struct blkcg *blkcg;
+-
+-retry:
+-	rcu_read_lock();
+-
+-	blkcg = bio_blkcg(bio);
+-	bfqg = bfq_find_alloc_group(bfqd, blkcg);
+-	/* bic always exists here */
+-	bfqq = bic_to_bfqq(bic, is_sync);
+-
+-	/*
+-	 * Always try a new alloc if we fall back to the OOM bfqq
+-	 * originally, since it should just be a temporary situation.
+-	 */
+-	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
+-		bfqq = NULL;
+-		if (new_bfqq) {
+-			bfqq = new_bfqq;
+-			new_bfqq = NULL;
+-		} else if (gfpflags_allow_blocking(gfp_mask)) {
+-			rcu_read_unlock();
+-			spin_unlock_irq(bfqd->queue->queue_lock);
+-			new_bfqq = kmem_cache_alloc_node(bfq_pool,
+-					gfp_mask | __GFP_ZERO,
+-					bfqd->queue->node);
+-			spin_lock_irq(bfqd->queue->queue_lock);
+-			if (new_bfqq)
+-				goto retry;
+-		} else {
+-			bfqq = kmem_cache_alloc_node(bfq_pool,
+-					gfp_mask | __GFP_ZERO,
+-					bfqd->queue->node);
+-		}
+-
+-		if (bfqq) {
+-			bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
+-                                      is_sync);
+-			bfq_init_entity(&bfqq->entity, bfqg);
+-			bfq_log_bfqq(bfqd, bfqq, "allocated");
+-		} else {
+-			bfqq = &bfqd->oom_bfqq;
+-			bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
+-		}
+-	}
+-
+-	if (new_bfqq)
+-		kmem_cache_free(bfq_pool, new_bfqq);
++	bfqq->soft_rt_next_start = bfq_greatest_from_now();
+ 
+-	rcu_read_unlock();
+-
+-	return bfqq;
++	/* first request is almost certainly seeky */
++	bfqq->seek_history = 1;
+ }
+ 
+ static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+@@ -3263,44 +3712,56 @@ static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+ }
+ 
+ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+-				       struct bio *bio, int is_sync,
+-				       struct bfq_io_cq *bic, gfp_t gfp_mask)
++				       struct bio *bio, bool is_sync,
++				       struct bfq_io_cq *bic)
+ {
+ 	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ 	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
+ 	struct bfq_queue **async_bfqq = NULL;
+-	struct bfq_queue *bfqq = NULL;
++	struct bfq_queue *bfqq;
++	struct bfq_group *bfqg;
+ 
+-	if (!is_sync) {
+-		struct blkcg *blkcg;
+-		struct bfq_group *bfqg;
++	rcu_read_lock();
+ 
+-		rcu_read_lock();
+-		blkcg = bio_blkcg(bio);
+-		rcu_read_unlock();
+-		bfqg = bfq_find_alloc_group(bfqd, blkcg);
++	bfqg = bfq_find_alloc_group(bfqd,bio_blkcg(bio));
++
++	if (!is_sync) {
+ 		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
+ 						  ioprio);
+ 		bfqq = *async_bfqq;
++		if (bfqq)
++			goto out;
+ 	}
+ 
+-	if (!bfqq)
+-		bfqq = bfq_find_alloc_queue(bfqd, bio, is_sync, bic, gfp_mask);
++	bfqq = kmem_cache_alloc_node(bfq_pool, GFP_NOWAIT | __GFP_ZERO,
++				     bfqd->queue->node);
++
++	if (bfqq) {
++		bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
++			      is_sync);
++		bfq_init_entity(&bfqq->entity, bfqg);
++		bfq_log_bfqq(bfqd, bfqq, "allocated");
++	} else {
++		bfqq = &bfqd->oom_bfqq;
++		bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
++		goto out;
++	}
+ 
+ 	/*
+ 	 * Pin the queue now that it's allocated, scheduler exit will
+ 	 * prune it.
+ 	 */
+-	if (!is_sync && !(*async_bfqq)) {
+-		atomic_inc(&bfqq->ref);
++	if (async_bfqq) {
++		bfqq->ref++;
+ 		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
+-			     bfqq, atomic_read(&bfqq->ref));
++			     bfqq, bfqq->ref);
+ 		*async_bfqq = bfqq;
+ 	}
+ 
+-	atomic_inc(&bfqq->ref);
+-	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq,
+-		     atomic_read(&bfqq->ref));
++out:
++	bfqq->ref++;
++	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
++	rcu_read_unlock();
+ 	return bfqq;
+ }
+ 
+@@ -3316,37 +3777,21 @@ static void bfq_update_io_thinktime(struct bfq_data *bfqd,
+ 				bic->ttime.ttime_samples;
+ }
+ 
+-static void bfq_update_io_seektime(struct bfq_data *bfqd,
+-				   struct bfq_queue *bfqq,
+-				   struct request *rq)
+-{
+-	sector_t sdist;
+-	u64 total;
+-
+-	if (bfqq->last_request_pos < blk_rq_pos(rq))
+-		sdist = blk_rq_pos(rq) - bfqq->last_request_pos;
+-	else
+-		sdist = bfqq->last_request_pos - blk_rq_pos(rq);
+-
+-	/*
+-	 * Don't allow the seek distance to get too large from the
+-	 * odd fragment, pagein, etc.
+-	 */
+-	if (bfqq->seek_samples == 0) /* first request, not really a seek */
+-		sdist = 0;
+-	else if (bfqq->seek_samples <= 60) /* second & third seek */
+-		sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024);
+-	else
+-		sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64);
+ 
+-	bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8;
+-	bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8;
+-	total = bfqq->seek_total + (bfqq->seek_samples/2);
+-	do_div(total, bfqq->seek_samples);
+-	bfqq->seek_mean = (sector_t)total;
++static void
++bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++		       struct request *rq)
++{
++	sector_t sdist = 0;
++	if (bfqq->last_request_pos) {
++		if (bfqq->last_request_pos < blk_rq_pos(rq))
++			sdist = blk_rq_pos(rq) - bfqq->last_request_pos;
++		else
++			sdist = bfqq->last_request_pos - blk_rq_pos(rq);
++	}
+ 
+-	bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist,
+-			(u64)bfqq->seek_mean);
++	bfqq->seek_history <<= 1;
++	bfqq->seek_history |= (sdist > BFQQ_SEEK_THR);
+ }
+ 
+ /*
+@@ -3364,7 +3809,8 @@ static void bfq_update_idle_window(struct bfq_data *bfqd,
+ 		return;
+ 
+ 	/* Idle window just restored, statistics are meaningless. */
+-	if (bfq_bfqq_just_split(bfqq))
++	if (time_is_after_eq_jiffies(bfqq->split_time +
++				     bfqd->bfq_wr_min_idle_time))
+ 		return;
+ 
+ 	enable_idle = bfq_bfqq_idle_window(bfqq);
+@@ -3404,22 +3850,13 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 
+ 	bfq_update_io_thinktime(bfqd, bic);
+ 	bfq_update_io_seektime(bfqd, bfqq, rq);
+-	if (!BFQQ_SEEKY(bfqq) && bfq_bfqq_constantly_seeky(bfqq)) {
+-		bfq_clear_bfqq_constantly_seeky(bfqq);
+-		if (!blk_queue_nonrot(bfqd->queue)) {
+-			BUG_ON(!bfqd->const_seeky_busy_in_flight_queues);
+-			bfqd->const_seeky_busy_in_flight_queues--;
+-		}
+-	}
+ 	if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ 	    !BFQQ_SEEKY(bfqq))
+ 		bfq_update_idle_window(bfqd, bfqq, bic);
+-	bfq_clear_bfqq_just_split(bfqq);
+ 
+ 	bfq_log_bfqq(bfqd, bfqq,
+-		     "rq_enqueued: idle_window=%d (seeky %d, mean %llu)",
+-		     bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq),
+-		     (long long unsigned)bfqq->seek_mean);
++		     "rq_enqueued: idle_window=%d (seeky %d)",
++		     bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq));
+ 
+ 	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+ 
+@@ -3433,14 +3870,15 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 		 * is small and the queue is not to be expired, then
+ 		 * just exit.
+ 		 *
+-		 * In this way, if the disk is being idled to wait for
+-		 * a new request from the in-service queue, we avoid
+-		 * unplugging the device and committing the disk to serve
+-		 * just a small request. On the contrary, we wait for
+-		 * the block layer to decide when to unplug the device:
+-		 * hopefully, new requests will be merged to this one
+-		 * quickly, then the device will be unplugged and
+-		 * larger requests will be dispatched.
++		 * In this way, if the device is being idled to wait
++		 * for a new request from the in-service queue, we
++		 * avoid unplugging the device and committing the
++		 * device to serve just a small request. On the
++		 * contrary, we wait for the block layer to decide
++		 * when to unplug the device: hopefully, new requests
++		 * will be merged to this one quickly, then the device
++		 * will be unplugged and larger requests will be
++		 * dispatched.
+ 		 */
+ 		if (small_req && !budget_timeout)
+ 			return;
+@@ -3453,9 +3891,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 		 */
+ 		bfq_clear_bfqq_wait_request(bfqq);
+ 		del_timer(&bfqd->idle_slice_timer);
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 		bfqg_stats_update_idle_time(bfqq_group(bfqq));
+-#endif
+ 
+ 		/*
+ 		 * The queue is not empty, because a new request just
+@@ -3499,27 +3935,19 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq)
+ 			 */
+ 			new_bfqq->allocated[rq_data_dir(rq)]++;
+ 			bfqq->allocated[rq_data_dir(rq)]--;
+-			atomic_inc(&new_bfqq->ref);
++			new_bfqq->ref++;
++			bfq_clear_bfqq_just_created(bfqq);
+ 			bfq_put_queue(bfqq);
+ 			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
+ 				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
+ 						bfqq, new_bfqq);
+ 			rq->elv.priv[1] = new_bfqq;
+ 			bfqq = new_bfqq;
+-		} else
+-			bfq_bfqq_increase_failed_cooperations(bfqq);
++		}
+ 	}
+ 
+ 	bfq_add_request(rq);
+ 
+-	/*
+-	 * Here a newly-created bfq_queue has already started a weight-raising
+-	 * period: clear raising_time_left to prevent bfq_bfqq_save_state()
+-	 * from assigning it a full weight-raising period. See the detailed
+-	 * comments about this field in bfq_init_icq().
+-	 */
+-	if (bfqq->bic)
+-		bfqq->bic->wr_time_left = 0;
+ 	rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
+ 	list_add_tail(&rq->queuelist, &bfqq->fifo);
+ 
+@@ -3528,8 +3956,8 @@ static void bfq_insert_request(struct request_queue *q, struct request *rq)
+ 
+ static void bfq_update_hw_tag(struct bfq_data *bfqd)
+ {
+-	bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver,
+-				     bfqd->rq_in_driver);
++	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
++				       bfqd->rq_in_driver);
+ 
+ 	if (bfqd->hw_tag == 1)
+ 		return;
+@@ -3560,43 +3988,41 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
+ 	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left (%d)",
+ 		     blk_rq_sectors(rq), sync);
+ 
++	assert_spin_locked(bfqd->queue->queue_lock);
+ 	bfq_update_hw_tag(bfqd);
+ 
+ 	BUG_ON(!bfqd->rq_in_driver);
+ 	BUG_ON(!bfqq->dispatched);
+ 	bfqd->rq_in_driver--;
+ 	bfqq->dispatched--;
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	bfqg_stats_update_completion(bfqq_group(bfqq),
+ 				     rq_start_time_ns(rq),
+ 				     rq_io_start_time_ns(rq), rq->cmd_flags);
+-#endif
+ 
+ 	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
++		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
++		/*
++		 * Set budget_timeout (which we overload to store the
++		 * time at which the queue remains with no backlog and
++		 * no outstanding request; used by the weight-raising
++		 * mechanism).
++		 */
++		bfqq->budget_timeout = jiffies;
++
+ 		bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ 					&bfqd->queue_weights_tree);
+-		if (!blk_queue_nonrot(bfqd->queue)) {
+-			BUG_ON(!bfqd->busy_in_flight_queues);
+-			bfqd->busy_in_flight_queues--;
+-			if (bfq_bfqq_constantly_seeky(bfqq)) {
+-				BUG_ON(!bfqd->
+-					const_seeky_busy_in_flight_queues);
+-				bfqd->const_seeky_busy_in_flight_queues--;
+-			}
+-		}
+ 	}
+ 
+-	if (sync) {
+-		bfqd->sync_flight--;
+-		RQ_BIC(rq)->ttime.last_end_request = jiffies;
+-	}
++	RQ_BIC(rq)->ttime.last_end_request = jiffies;
+ 
+ 	/*
+-	 * If we are waiting to discover whether the request pattern of the
+-	 * task associated with the queue is actually isochronous, and
+-	 * both requisites for this condition to hold are satisfied, then
+-	 * compute soft_rt_next_start (see the comments to the function
+-	 * bfq_bfqq_softrt_next_start()).
++	 * If we are waiting to discover whether the request pattern
++	 * of the task associated with the queue is actually
++	 * isochronous, and both requisites for this condition to hold
++	 * are now satisfied, then compute soft_rt_next_start (see the
++	 * comments on the function bfq_bfqq_softrt_next_start()). We
++	 * schedule this delayed check when bfqq expires, if it still
++	 * has in-flight requests.
+ 	 */
+ 	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
+ 	    RB_EMPTY_ROOT(&bfqq->sort_list))
+@@ -3608,10 +4034,7 @@ static void bfq_completed_request(struct request_queue *q, struct request *rq)
+ 	 * or if we want to idle in case it has no pending requests.
+ 	 */
+ 	if (bfqd->in_service_queue == bfqq) {
+-		if (bfq_bfqq_budget_new(bfqq))
+-			bfq_set_budget_timeout(bfqd);
+-
+-		if (bfq_bfqq_must_idle(bfqq)) {
++		if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
+ 			bfq_arm_slice_timer(bfqd);
+ 			goto out;
+ 		} else if (bfq_may_expire_for_budg_timeout(bfqq))
+@@ -3682,14 +4105,14 @@ static void bfq_put_request(struct request *rq)
+ 		rq->elv.priv[1] = NULL;
+ 
+ 		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
+-			     bfqq, atomic_read(&bfqq->ref));
++			     bfqq, bfqq->ref);
+ 		bfq_put_queue(bfqq);
+ 	}
+ }
+ 
+ /*
+  * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
+- * was the last process referring to said bfqq.
++ * was the last process referring to that bfqq.
+  */
+ static struct bfq_queue *
+ bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
+@@ -3727,11 +4150,8 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
+ 	unsigned long flags;
+ 	bool split = false;
+ 
+-	might_sleep_if(gfpflags_allow_blocking(gfp_mask));
+-
+-	bfq_check_ioprio_change(bic, bio);
+-
+ 	spin_lock_irqsave(q->queue_lock, flags);
++	bfq_check_ioprio_change(bic, bio);
+ 
+ 	if (!bic)
+ 		goto queue_fail;
+@@ -3741,23 +4161,47 @@ static int bfq_set_request(struct request_queue *q, struct request *rq,
+ new_queue:
+ 	bfqq = bic_to_bfqq(bic, is_sync);
+ 	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
+-		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic, gfp_mask);
++		if (bfqq)
++			bfq_put_queue(bfqq);
++		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
++		BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
++
+ 		bic_set_bfqq(bic, bfqq, is_sync);
+ 		if (split && is_sync) {
++			bfq_log_bfqq(bfqd, bfqq,
++				     "set_request: was_in_list %d "
++				     "was_in_large_burst %d "
++				     "large burst in progress %d",
++				     bic->was_in_burst_list,
++				     bic->saved_in_large_burst,
++				     bfqd->large_burst);
++
+ 			if ((bic->was_in_burst_list && bfqd->large_burst) ||
+-			    bic->saved_in_large_burst)
++			    bic->saved_in_large_burst) {
++				bfq_log_bfqq(bfqd, bfqq,
++					     "set_request: marking in "
++					     "large burst");
+ 				bfq_mark_bfqq_in_large_burst(bfqq);
+-			else {
+-			    bfq_clear_bfqq_in_large_burst(bfqq);
+-			    if (bic->was_in_burst_list)
+-			       hlist_add_head(&bfqq->burst_list_node,
+-				              &bfqd->burst_list);
++			} else {
++				bfq_log_bfqq(bfqd, bfqq,
++					     "set_request: clearing in "
++					     "large burst");
++				bfq_clear_bfqq_in_large_burst(bfqq);
++				if (bic->was_in_burst_list)
++					hlist_add_head(&bfqq->burst_list_node,
++						       &bfqd->burst_list);
+ 			}
++			bfqq->split_time = jiffies;
+ 		}
+ 	} else {
+ 		/* If the queue was seeky for too long, break it apart. */
+ 		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
+ 			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
++
++			/* Update bic before losing reference to bfqq */
++			if (bfq_bfqq_in_large_burst(bfqq))
++				bic->saved_in_large_burst = true;
++
+ 			bfqq = bfq_split_bfqq(bic, bfqq);
+ 			split = true;
+ 			if (!bfqq)
+@@ -3766,9 +4210,8 @@ new_queue:
+ 	}
+ 
+ 	bfqq->allocated[rw]++;
+-	atomic_inc(&bfqq->ref);
+-	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq,
+-		     atomic_read(&bfqq->ref));
++	bfqq->ref++;
++	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
+ 
+ 	rq->elv.priv[0] = bic;
+ 	rq->elv.priv[1] = bfqq;
+@@ -3783,7 +4226,6 @@ new_queue:
+ 	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
+ 		bfqq->bic = bic;
+ 		if (split) {
+-			bfq_mark_bfqq_just_split(bfqq);
+ 			/*
+ 			 * If the queue has just been split from a shared
+ 			 * queue, restore the idle window and the possible
+@@ -3793,6 +4235,9 @@ new_queue:
+ 		}
+ 	}
+ 
++	if (unlikely(bfq_bfqq_just_created(bfqq)))
++		bfq_handle_burst(bfqd, bfqq);
++
+ 	spin_unlock_irqrestore(q->queue_lock, flags);
+ 
+ 	return 0;
+@@ -3872,6 +4317,7 @@ static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
+ 	cancel_work_sync(&bfqd->unplug_work);
+ }
+ 
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ 					struct bfq_queue **bfqq_ptr)
+ {
+@@ -3880,9 +4326,9 @@ static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ 
+ 	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
+ 	if (bfqq) {
+-		bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group);
++		bfq_bfqq_move(bfqd, bfqq, root_group);
+ 		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
+-			     bfqq, atomic_read(&bfqq->ref));
++			     bfqq, bfqq->ref);
+ 		bfq_put_queue(bfqq);
+ 		*bfqq_ptr = NULL;
+ 	}
+@@ -3904,6 +4350,7 @@ static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
+ 
+ 	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
+ }
++#endif
+ 
+ static void bfq_exit_queue(struct elevator_queue *e)
+ {
+@@ -3923,8 +4370,6 @@ static void bfq_exit_queue(struct elevator_queue *e)
+ 
+ 	bfq_shutdown_timer_wq(bfqd);
+ 
+-	synchronize_rcu();
+-
+ 	BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+ 
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+@@ -3973,11 +4418,14 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+ 	 * will not attempt to free it.
+ 	 */
+ 	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
+-	atomic_inc(&bfqd->oom_bfqq.ref);
++	bfqd->oom_bfqq.ref++;
+ 	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
+ 	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
+ 	bfqd->oom_bfqq.entity.new_weight =
+ 		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
++
++	/* oom_bfqq does not participate to bursts */
++	bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
+ 	/*
+ 	 * Trigger weight initialization, according to ioprio, at the
+ 	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
+@@ -3996,9 +4444,6 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+ 		goto out_free;
+ 	bfq_init_root_group(bfqd->root_group, bfqd);
+ 	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+-	bfqd->active_numerous_groups = 0;
+-#endif
+ 
+ 	init_timer(&bfqd->idle_slice_timer);
+ 	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
+@@ -4023,20 +4468,19 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+ 	bfqd->bfq_back_penalty = bfq_back_penalty;
+ 	bfqd->bfq_slice_idle = bfq_slice_idle;
+ 	bfqd->bfq_class_idle_last_service = 0;
+-	bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq;
+-	bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async;
+-	bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync;
++	bfqd->bfq_timeout = bfq_timeout;
+ 
+-	bfqd->bfq_coop_thresh = 2;
+-	bfqd->bfq_failed_cooperations = 7000;
+ 	bfqd->bfq_requests_within_timer = 120;
+ 
+-	bfqd->bfq_large_burst_thresh = 11;
+-	bfqd->bfq_burst_interval = msecs_to_jiffies(500);
++	bfqd->bfq_large_burst_thresh = 8;
++	bfqd->bfq_burst_interval = msecs_to_jiffies(180);
+ 
+ 	bfqd->low_latency = true;
+ 
+-	bfqd->bfq_wr_coeff = 20;
++	/*
++	 * Trade-off between responsiveness and fairness.
++	 */
++	bfqd->bfq_wr_coeff = 30;
+ 	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
+ 	bfqd->bfq_wr_max_time = 0;
+ 	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
+@@ -4048,16 +4492,15 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+ 					      * video.
+ 					      */
+ 	bfqd->wr_busy_queues = 0;
+-	bfqd->busy_in_flight_queues = 0;
+-	bfqd->const_seeky_busy_in_flight_queues = 0;
+ 
+ 	/*
+-	 * Begin by assuming, optimistically, that the device peak rate is
+-	 * equal to the highest reference rate.
++	 * Begin by assuming, optimistically, that the device is a
++	 * high-speed one, and that its peak rate is equal to 2/3 of
++	 * the highest reference rate.
+ 	 */
+ 	bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
+ 			T_fast[blk_queue_nonrot(bfqd->queue)];
+-	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)];
++	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
+ 	bfqd->device_speed = BFQ_BFQD_FAST;
+ 
+ 	return 0;
+@@ -4161,10 +4604,8 @@ SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
+ SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
+ SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1);
+ SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
+-SHOW_FUNCTION(bfq_max_budget_async_rq_show,
+-	      bfqd->bfq_max_budget_async_rq, 0);
+-SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1);
+-SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1);
++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
++SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
+ SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
+ SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
+ SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
+@@ -4199,10 +4640,6 @@ STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
+ STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
+ 		INT_MAX, 0);
+ STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1);
+-STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq,
+-		1, INT_MAX, 0);
+-STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0,
+-		INT_MAX, 1);
+ STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
+ STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
+ STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
+@@ -4224,10 +4661,8 @@ static ssize_t bfq_weights_store(struct elevator_queue *e,
+ 
+ static unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd)
+ {
+-	u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
+-
+ 	if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES)
+-		return bfq_calc_max_budget(bfqd->peak_rate, timeout);
++		return bfq_calc_max_budget(bfqd);
+ 	else
+ 		return bfq_default_max_budget;
+ }
+@@ -4252,6 +4687,10 @@ static ssize_t bfq_max_budget_store(struct elevator_queue *e,
+ 	return ret;
+ }
+ 
++/* 
++ * Leaving this name to preserve name compatibility with cfq
++ * parameters, but this timeout is used for both sync and async.
++ */
+ static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ 				      const char *page, size_t count)
+ {
+@@ -4264,13 +4703,31 @@ static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ 	else if (__data > INT_MAX)
+ 		__data = INT_MAX;
+ 
+-	bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data);
++	bfqd->bfq_timeout = msecs_to_jiffies(__data);
+ 	if (bfqd->bfq_user_max_budget == 0)
+ 		bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+ 
+ 	return ret;
+ }
+ 
++static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
++				     const char *page, size_t count)
++{
++	struct bfq_data *bfqd = e->elevator_data;
++	unsigned long uninitialized_var(__data);
++	int ret = bfq_var_store(&__data, (page), count);
++
++	if (__data > 1)
++		__data = 1;
++	if (!bfqd->strict_guarantees && __data == 1
++	    && bfqd->bfq_slice_idle < msecs_to_jiffies(8))
++		bfqd->bfq_slice_idle = msecs_to_jiffies(8);
++
++	bfqd->strict_guarantees = __data;
++
++	return ret;
++}
++
+ static ssize_t bfq_low_latency_store(struct elevator_queue *e,
+ 				     const char *page, size_t count)
+ {
+@@ -4297,9 +4754,8 @@ static struct elv_fs_entry bfq_attrs[] = {
+ 	BFQ_ATTR(back_seek_penalty),
+ 	BFQ_ATTR(slice_idle),
+ 	BFQ_ATTR(max_budget),
+-	BFQ_ATTR(max_budget_async_rq),
+ 	BFQ_ATTR(timeout_sync),
+-	BFQ_ATTR(timeout_async),
++	BFQ_ATTR(strict_guarantees),
+ 	BFQ_ATTR(low_latency),
+ 	BFQ_ATTR(wr_coeff),
+ 	BFQ_ATTR(wr_max_time),
+@@ -4342,9 +4798,28 @@ static struct elevator_type iosched_bfq = {
+ 	.elevator_owner =	THIS_MODULE,
+ };
+ 
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++static struct blkcg_policy blkcg_policy_bfq = {
++	.dfl_cftypes		= bfq_blkg_files,
++	.legacy_cftypes		= bfq_blkcg_legacy_files,
++
++	.cpd_alloc_fn		= bfq_cpd_alloc,
++	.cpd_init_fn		= bfq_cpd_init,
++	.cpd_bind_fn	        = bfq_cpd_init,
++	.cpd_free_fn		= bfq_cpd_free,
++
++	.pd_alloc_fn		= bfq_pd_alloc,
++	.pd_init_fn		= bfq_pd_init,
++	.pd_offline_fn		= bfq_pd_offline,
++	.pd_free_fn		= bfq_pd_free,
++	.pd_reset_stats_fn	= bfq_pd_reset_stats,
++};
++#endif
++
+ static int __init bfq_init(void)
+ {
+ 	int ret;
++	char msg[50] = "BFQ I/O-scheduler: v8";
+ 
+ 	/*
+ 	 * Can be 0 on HZ < 1000 setups.
+@@ -4352,9 +4827,6 @@ static int __init bfq_init(void)
+ 	if (bfq_slice_idle == 0)
+ 		bfq_slice_idle = 1;
+ 
+-	if (bfq_timeout_async == 0)
+-		bfq_timeout_async = 1;
+-
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	ret = blkcg_policy_register(&blkcg_policy_bfq);
+ 	if (ret)
+@@ -4370,23 +4842,34 @@ static int __init bfq_init(void)
+ 	 * installed on the reference devices (see the comments before the
+ 	 * definitions of the two arrays).
+ 	 */
+-	T_slow[0] = msecs_to_jiffies(2600);
+-	T_slow[1] = msecs_to_jiffies(1000);
+-	T_fast[0] = msecs_to_jiffies(5500);
+-	T_fast[1] = msecs_to_jiffies(2000);
++	T_slow[0] = msecs_to_jiffies(3500);
++	T_slow[1] = msecs_to_jiffies(1500);
++	T_fast[0] = msecs_to_jiffies(8000);
++	T_fast[1] = msecs_to_jiffies(3000);
+ 
+ 	/*
+-	 * Thresholds that determine the switch between speed classes (see
+-	 * the comments before the definition of the array).
++	 * Thresholds that determine the switch between speed classes
++	 * (see the comments before the definition of the array
++	 * device_speed_thresh). These thresholds are biased towards
++	 * transitions to the fast class. This is safer than the
++	 * opposite bias. In fact, a wrong transition to the slow
++	 * class results in short weight-raising periods, because the
++	 * speed of the device then tends to be higher that the
++	 * reference peak rate. On the opposite end, a wrong
++	 * transition to the fast class tends to increase
++	 * weight-raising periods, because of the opposite reason.
+ 	 */
+-	device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2;
+-	device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2;
++	device_speed_thresh[0] = (4 * R_slow[0]) / 3;
++	device_speed_thresh[1] = (4 * R_slow[1]) / 3;
+ 
+ 	ret = elv_register(&iosched_bfq);
+ 	if (ret)
+ 		goto err_pol_unreg;
+ 
+-	pr_info("BFQ I/O-scheduler: v7r11");
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	strcat(msg, " (with cgroups support)");
++#endif
++	pr_info("%s", msg);
+ 
+ 	return 0;
+ 
+diff --git a/block/bfq-sched.c b/block/bfq-sched.c
+index a64fec1..e54b149 100644
+--- a/block/bfq-sched.c
++++ b/block/bfq-sched.c
+@@ -7,9 +7,11 @@
+  * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+  *		      Paolo Valente <paolo.valente@unimore.it>
+  *
+- * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
++ * Copyright (C) 2016 Paolo Valente <paolo.valente@unimore.it>
+  */
+ 
++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
++
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+ #define for_each_entity(entity)	\
+ 	for (; entity ; entity = entity->parent)
+@@ -22,8 +24,6 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ 						 int extract,
+ 						 struct bfq_data *bfqd);
+ 
+-static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
+-
+ static void bfq_update_budget(struct bfq_entity *next_in_service)
+ {
+ 	struct bfq_entity *bfqg_entity;
+@@ -48,6 +48,7 @@ static void bfq_update_budget(struct bfq_entity *next_in_service)
+ static int bfq_update_next_in_service(struct bfq_sched_data *sd)
+ {
+ 	struct bfq_entity *next_in_service;
++	struct bfq_queue *bfqq;
+ 
+ 	if (sd->in_service_entity)
+ 		/* will update/requeue at the end of service */
+@@ -65,14 +66,29 @@ static int bfq_update_next_in_service(struct bfq_sched_data *sd)
+ 
+ 	if (next_in_service)
+ 		bfq_update_budget(next_in_service);
++	else
++		goto exit;
+ 
++	bfqq = bfq_entity_to_bfqq(next_in_service);
++	if (bfqq)
++		bfq_log_bfqq(bfqq->bfqd, bfqq,
++			     "update_next_in_service: chosen this queue");
++	else {
++		struct bfq_group *bfqg =
++			container_of(next_in_service,
++				     struct bfq_group, entity);
++
++		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++			     "update_next_in_service: chosen this entity");
++	}
++exit:
+ 	return 1;
+ }
+ 
+ static void bfq_check_next_in_service(struct bfq_sched_data *sd,
+ 				      struct bfq_entity *entity)
+ {
+-	BUG_ON(sd->next_in_service != entity);
++	WARN_ON(sd->next_in_service != entity);
+ }
+ #else
+ #define for_each_entity(entity)	\
+@@ -151,20 +167,35 @@ static u64 bfq_delta(unsigned long service, unsigned long weight)
+ static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
+ {
+ 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+-
++	unsigned long long start, finish, delta ;
+ 	BUG_ON(entity->weight == 0);
+ 
+ 	entity->finish = entity->start +
+ 		bfq_delta(service, entity->weight);
+ 
++	start = ((entity->start>>10)*1000)>>12;
++	finish = ((entity->finish>>10)*1000)>>12;
++	delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12;
++
+ 	if (bfqq) {
+ 		bfq_log_bfqq(bfqq->bfqd, bfqq,
+ 			"calc_finish: serv %lu, w %d",
+ 			service, entity->weight);
+ 		bfq_log_bfqq(bfqq->bfqd, bfqq,
+ 			"calc_finish: start %llu, finish %llu, delta %llu",
+-			entity->start, entity->finish,
+-			bfq_delta(service, entity->weight));
++			start, finish, delta);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	} else {
++		struct bfq_group *bfqg =
++			container_of(entity, struct bfq_group, entity);
++
++		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++			"calc_finish group: serv %lu, w %d",
++			     service, entity->weight);
++		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++			"calc_finish group: start %llu, finish %llu, delta %llu",
++			start, finish, delta);
++#endif
+ 	}
+ }
+ 
+@@ -386,8 +417,6 @@ static void bfq_active_insert(struct bfq_service_tree *st,
+ 		BUG_ON(!bfqg);
+ 		BUG_ON(!bfqd);
+ 		bfqg->active_entities++;
+-		if (bfqg->active_entities == 2)
+-			bfqd->active_numerous_groups++;
+ 	}
+ #endif
+ }
+@@ -399,7 +428,7 @@ static void bfq_active_insert(struct bfq_service_tree *st,
+ static unsigned short bfq_ioprio_to_weight(int ioprio)
+ {
+ 	BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
+-	return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - ioprio;
++	return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF ;
+ }
+ 
+ /**
+@@ -422,9 +451,9 @@ static void bfq_get_entity(struct bfq_entity *entity)
+ 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ 
+ 	if (bfqq) {
+-		atomic_inc(&bfqq->ref);
++		bfqq->ref++;
+ 		bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
+-			     bfqq, atomic_read(&bfqq->ref));
++			     bfqq, bfqq->ref);
+ 	}
+ }
+ 
+@@ -499,10 +528,6 @@ static void bfq_active_extract(struct bfq_service_tree *st,
+ 		BUG_ON(!bfqd);
+ 		BUG_ON(!bfqg->active_entities);
+ 		bfqg->active_entities--;
+-		if (bfqg->active_entities == 1) {
+-			BUG_ON(!bfqd->active_numerous_groups);
+-			bfqd->active_numerous_groups--;
+-		}
+ 	}
+ #endif
+ }
+@@ -552,7 +577,7 @@ static void bfq_forget_entity(struct bfq_service_tree *st,
+ 	if (bfqq) {
+ 		sd = entity->sched_data;
+ 		bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d",
+-			     bfqq, atomic_read(&bfqq->ref));
++			     bfqq, bfqq->ref);
+ 		bfq_put_queue(bfqq);
+ 	}
+ }
+@@ -628,12 +653,14 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
+ 		if (entity->new_weight != entity->orig_weight) {
+ 			if (entity->new_weight < BFQ_MIN_WEIGHT ||
+ 			    entity->new_weight > BFQ_MAX_WEIGHT) {
+-				printk(KERN_CRIT "update_weight_prio: "
+-						 "new_weight %d\n",
++				pr_crit("update_weight_prio: new_weight %d\n",
+ 					entity->new_weight);
+-				BUG();
++				if (entity->new_weight < BFQ_MIN_WEIGHT)
++					entity->new_weight = BFQ_MIN_WEIGHT;
++				else
++					entity->new_weight = BFQ_MAX_WEIGHT;
+ 			}
+-			entity->orig_weight = entity->new_weight;
++		       	entity->orig_weight = entity->new_weight;
+ 			if (bfqq)
+ 				bfqq->ioprio =
+ 				  bfq_weight_to_ioprio(entity->orig_weight);
+@@ -708,7 +735,7 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
+ 		st = bfq_entity_service_tree(entity);
+ 
+ 		entity->service += served;
+-		BUG_ON(entity->service > entity->budget);
++
+ 		BUG_ON(st->wsum == 0);
+ 
+ 		st->vtime += bfq_delta(served, st->wsum);
+@@ -717,31 +744,69 @@ static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
+ #endif
+-	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served);
++	st = bfq_entity_service_tree(&bfqq->entity);
++	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p",
++		     served,  ((st->vtime>>10)*1000)>>12, st);
+ }
+ 
+ /**
+- * bfq_bfqq_charge_full_budget - set the service to the entity budget.
++ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
++ *			  of the time interval during which bfqq has been in
++ *			  service.
++ * @bfqd: the device
+  * @bfqq: the queue that needs a service update.
++ * @time_ms: the amount of time during which the queue has received service
++ *
++ * If a queue does not consume its budget fast enough, then providing
++ * the queue with service fairness may impair throughput, more or less
++ * severely. For this reason, queues that consume their budget slowly
++ * are provided with time fairness instead of service fairness. This
++ * goal is achieved through the BFQ scheduling engine, even if such an
++ * engine works in the service, and not in the time domain. The trick
++ * is charging these queues with an inflated amount of service, equal
++ * to the amount of service that they would have received during their
++ * service slot if they had been fast, i.e., if their requests had
++ * been dispatched at a rate equal to the estimated peak rate.
+  *
+- * When it's not possible to be fair in the service domain, because
+- * a queue is not consuming its budget fast enough (the meaning of
+- * fast depends on the timeout parameter), we charge it a full
+- * budget.  In this way we should obtain a sort of time-domain
+- * fairness among all the seeky/slow queues.
++ * It is worth noting that time fairness can cause important
++ * distortions in terms of bandwidth distribution, on devices with
++ * internal queueing. The reason is that I/O requests dispatched
++ * during the service slot of a queue may be served after that service
++ * slot is finished, and may have a total processing time loosely
++ * correlated with the duration of the service slot. This is
++ * especially true for short service slots.
+  */
+-static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq)
++static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
++				 unsigned long time_ms)
+ {
+ 	struct bfq_entity *entity = &bfqq->entity;
++	int tot_serv_to_charge = entity->service;
++	unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout);
++
++	if (time_ms > 0 && time_ms < timeout_ms)
++		tot_serv_to_charge =
++			(bfqd->bfq_max_budget * time_ms) / timeout_ms;
++
++	if (tot_serv_to_charge < entity->service)
++		tot_serv_to_charge = entity->service;
++
++	bfq_log_bfqq(bfqq->bfqd, bfqq,
++		     "charge_time: %lu/%u ms, %d/%d/%d sectors",
++		     time_ms, timeout_ms, entity->service,
++		     tot_serv_to_charge, entity->budget);
+ 
+-	bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget");
++	/* Increase budget to avoid inconsistencies */
++	if (tot_serv_to_charge > entity->budget)
++		entity->budget = tot_serv_to_charge;
+ 
+-	bfq_bfqq_served(bfqq, entity->budget - entity->service);
++	bfq_bfqq_served(bfqq,
++			max_t(int, 0, tot_serv_to_charge - entity->service));
+ }
+ 
+ /**
+  * __bfq_activate_entity - activate an entity.
+  * @entity: the entity being activated.
++ * @non_blocking_wait_rq: true if this entity was waiting for a request
+  *
+  * Called whenever an entity is activated, i.e., it is not active and one
+  * of its children receives a new request, or has to be reactivated due to
+@@ -749,11 +814,16 @@ static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq)
+  * service received if @entity is active) of the queue to calculate its
+  * timestamps.
+  */
+-static void __bfq_activate_entity(struct bfq_entity *entity)
++static void __bfq_activate_entity(struct bfq_entity *entity,
++				  bool non_blocking_wait_rq)
+ {
+ 	struct bfq_sched_data *sd = entity->sched_data;
+ 	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
++	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++	bool backshifted = false;
+ 
++	BUG_ON(!sd);
++	BUG_ON(!st);
+ 	if (entity == sd->in_service_entity) {
+ 		BUG_ON(entity->tree);
+ 		/*
+@@ -771,45 +841,133 @@ static void __bfq_activate_entity(struct bfq_entity *entity)
+ 		 * old start time.
+ 		 */
+ 		bfq_active_extract(st, entity);
+-	} else if (entity->tree == &st->idle) {
+-		/*
+-		 * Must be on the idle tree, bfq_idle_extract() will
+-		 * check for that.
+-		 */
+-		bfq_idle_extract(st, entity);
+-		entity->start = bfq_gt(st->vtime, entity->finish) ?
+-				       st->vtime : entity->finish;
+ 	} else {
+-		/*
+-		 * The finish time of the entity may be invalid, and
+-		 * it is in the past for sure, otherwise the queue
+-		 * would have been on the idle tree.
+-		 */
+-		entity->start = st->vtime;
+-		st->wsum += entity->weight;
+-		bfq_get_entity(entity);
++		unsigned long long min_vstart;
++
++		/* See comments on bfq_fqq_update_budg_for_activation */
++		if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
++			backshifted = true;
++			min_vstart = entity->finish;
++		} else
++			min_vstart = st->vtime;
+ 
+-		BUG_ON(entity->on_st);
+-		entity->on_st = 1;
++		if (entity->tree == &st->idle) {
++			/*
++			 * Must be on the idle tree, bfq_idle_extract() will
++			 * check for that.
++			 */
++			bfq_idle_extract(st, entity);
++			entity->start = bfq_gt(min_vstart, entity->finish) ?
++				min_vstart : entity->finish;
++		} else {
++			/*
++			 * The finish time of the entity may be invalid, and
++			 * it is in the past for sure, otherwise the queue
++			 * would have been on the idle tree.
++			 */
++			entity->start = min_vstart;
++			st->wsum += entity->weight;
++			bfq_get_entity(entity);
++
++			BUG_ON(entity->on_st);
++			entity->on_st = 1;
++		}
+ 	}
+ 
+ 	st = __bfq_entity_update_weight_prio(st, entity);
+ 	bfq_calc_finish(entity, entity->budget);
++
++	/*
++	 * If some queues enjoy backshifting for a while, then their
++	 * (virtual) finish timestamps may happen to become lower and
++	 * lower than the system virtual time.  In particular, if
++	 * these queues often happen to be idle for short time
++	 * periods, and during such time periods other queues with
++	 * higher timestamps happen to be busy, then the backshifted
++	 * timestamps of the former queues can become much lower than
++	 * the system virtual time. In fact, to serve the queues with
++	 * higher timestamps while the ones with lower timestamps are
++	 * idle, the system virtual time may be pushed-up to much
++	 * higher values than the finish timestamps of the idle
++	 * queues. As a consequence, the finish timestamps of all new
++	 * or newly activated queues may end up being much larger than
++	 * those of lucky queues with backshifted timestamps. The
++	 * latter queues may then monopolize the device for a lot of
++	 * time. This would simply break service guarantees.
++	 *
++	 * To reduce this problem, push up a little bit the
++	 * backshifted timestamps of the queue associated with this
++	 * entity (only a queue can happen to have the backshifted
++	 * flag set): just enough to let the finish timestamp of the
++	 * queue be equal to the current value of the system virtual
++	 * time. This may introduce a little unfairness among queues
++	 * with backshifted timestamps, but it does not break
++	 * worst-case fairness guarantees.
++	 *
++	 * As a special case, if bfqq is weight-raised, push up
++	 * timestamps much less, to keep very low the probability that
++	 * this push up causes the backshifted finish timestamps of
++	 * weight-raised queues to become higher than the backshifted
++	 * finish timestamps of non weight-raised queues.
++	 */
++	if (backshifted && bfq_gt(st->vtime, entity->finish)) {
++		unsigned long delta = st->vtime - entity->finish;
++
++		if (bfqq)
++			delta /= bfqq->wr_coeff;
++
++		entity->start += delta;
++		entity->finish += delta;
++
++		if (bfqq) {
++			bfq_log_bfqq(bfqq->bfqd, bfqq,
++				     "__activate_entity: new queue finish %llu",
++				     ((entity->finish>>10)*1000)>>12);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		} else {
++			struct bfq_group *bfqg =
++				container_of(entity, struct bfq_group, entity);
++
++			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++				     "__activate_entity: new group finish %llu",
++				     ((entity->finish>>10)*1000)>>12);
++#endif
++		}
++	}
++
+ 	bfq_active_insert(st, entity);
++
++	if (bfqq) {
++		bfq_log_bfqq(bfqq->bfqd, bfqq,
++			"__activate_entity: queue %seligible in st %p",
++			     entity->start <= st->vtime ? "" : "non ", st);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	} else {
++		struct bfq_group *bfqg =
++			container_of(entity, struct bfq_group, entity);
++
++		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++			"__activate_entity: group %seligible in st %p",
++			     entity->start <= st->vtime ? "" : "non ", st);
++#endif
++	}
+ }
+ 
+ /**
+  * bfq_activate_entity - activate an entity and its ancestors if necessary.
+  * @entity: the entity to activate.
++ * @non_blocking_wait_rq: true if this entity was waiting for a request
+  *
+  * Activate @entity and all the entities on the path from it to the root.
+  */
+-static void bfq_activate_entity(struct bfq_entity *entity)
++static void bfq_activate_entity(struct bfq_entity *entity,
++				bool non_blocking_wait_rq)
+ {
+ 	struct bfq_sched_data *sd;
+ 
+ 	for_each_entity(entity) {
+-		__bfq_activate_entity(entity);
++		BUG_ON(!entity);
++		__bfq_activate_entity(entity, non_blocking_wait_rq);
+ 
+ 		sd = entity->sched_data;
+ 		if (!bfq_update_next_in_service(sd))
+@@ -890,23 +1048,24 @@ static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+ 
+ 		if (!__bfq_deactivate_entity(entity, requeue))
+ 			/*
+-			 * The parent entity is still backlogged, and
+-			 * we don't need to update it as it is still
+-			 * in service.
++			 * next_in_service has not been changed, so
++			 * no upwards update is needed
+ 			 */
+ 			break;
+ 
+ 		if (sd->next_in_service)
+ 			/*
+-			 * The parent entity is still backlogged and
+-			 * the budgets on the path towards the root
+-			 * need to be updated.
++			 * The parent entity is still backlogged,
++			 * because next_in_service is not NULL, and
++			 * next_in_service has been updated (see
++			 * comment on the body of the above if):
++			 * upwards update of the schedule is needed.
+ 			 */
+ 			goto update;
+ 
+ 		/*
+-		 * If we reach there the parent is no more backlogged and
+-		 * we want to propagate the dequeue upwards.
++		 * If we get here, then the parent is no more backlogged and
++		 * we want to propagate the deactivation upwards.
+ 		 */
+ 		requeue = 1;
+ 	}
+@@ -916,9 +1075,23 @@ static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+ update:
+ 	entity = parent;
+ 	for_each_entity(entity) {
+-		__bfq_activate_entity(entity);
++		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++		__bfq_activate_entity(entity, false);
+ 
+ 		sd = entity->sched_data;
++		if (bfqq)
++			bfq_log_bfqq(bfqq->bfqd, bfqq,
++				     "invoking udpdate_next for this queue");
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		else {
++			struct bfq_group *bfqg =
++				container_of(entity,
++					     struct bfq_group, entity);
++
++			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++				     "invoking udpdate_next for this entity");
++		}
++#endif
+ 		if (!bfq_update_next_in_service(sd))
+ 			break;
+ 	}
+@@ -997,10 +1170,11 @@ left:
+  * Update the virtual time in @st and return the first eligible entity
+  * it contains.
+  */
+-static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st,
+-						   bool force)
++static struct bfq_entity *
++__bfq_lookup_next_entity(struct bfq_service_tree *st, bool force)
+ {
+ 	struct bfq_entity *entity, *new_next_in_service = NULL;
++	struct bfq_queue *bfqq;
+ 
+ 	if (RB_EMPTY_ROOT(&st->active))
+ 		return NULL;
+@@ -1009,6 +1183,24 @@ static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st,
+ 	entity = bfq_first_active_entity(st);
+ 	BUG_ON(bfq_gt(entity->start, st->vtime));
+ 
++	bfqq = bfq_entity_to_bfqq(entity);
++	if (bfqq)
++		bfq_log_bfqq(bfqq->bfqd, bfqq,
++			     "__lookup_next: start %llu vtime %llu st %p",
++			     ((entity->start>>10)*1000)>>12,
++			     ((st->vtime>>10)*1000)>>12, st);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	else {
++		struct bfq_group *bfqg =
++			container_of(entity, struct bfq_group, entity);
++
++		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++			     "__lookup_next: start %llu vtime %llu st %p",
++			     ((entity->start>>10)*1000)>>12,
++			     ((st->vtime>>10)*1000)>>12, st);
++	}
++#endif
++
+ 	/*
+ 	 * If the chosen entity does not match with the sched_data's
+ 	 * next_in_service and we are forcedly serving the IDLE priority
+@@ -1045,10 +1237,28 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ 	BUG_ON(sd->in_service_entity);
+ 
+ 	if (bfqd &&
+-	    jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) {
++	    jiffies - bfqd->bfq_class_idle_last_service >
++	    BFQ_CL_IDLE_TIMEOUT) {
+ 		entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1,
+ 						  true);
+ 		if (entity) {
++			struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++			if (bfqq)
++				bfq_log_bfqq(bfqd, bfqq,
++					     "idle chosen from st %p %d",
++					     st + BFQ_IOPRIO_CLASSES - 1,
++					BFQ_IOPRIO_CLASSES - 1) ;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++			else {
++				struct bfq_group *bfqg =
++				container_of(entity, struct bfq_group, entity);
++
++				bfq_log_bfqg(bfqd, bfqg,
++					     "idle chosen from st %p %d",
++					     st + BFQ_IOPRIO_CLASSES - 1,
++					BFQ_IOPRIO_CLASSES - 1) ;
++			}
++#endif
+ 			i = BFQ_IOPRIO_CLASSES - 1;
+ 			bfqd->bfq_class_idle_last_service = jiffies;
+ 			sd->next_in_service = entity;
+@@ -1057,6 +1267,24 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ 	for (; i < BFQ_IOPRIO_CLASSES; i++) {
+ 		entity = __bfq_lookup_next_entity(st + i, false);
+ 		if (entity) {
++			if (bfqd != NULL) {
++			struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
++			if (bfqq)
++				bfq_log_bfqq(bfqd, bfqq,
++					     "chosen from st %p %d",
++					     st + i, i) ;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++			else {
++				struct bfq_group *bfqg =
++				container_of(entity, struct bfq_group, entity);
++
++				bfq_log_bfqg(bfqd, bfqg,
++					     "chosen from st %p %d",
++					     st + i, i) ;
++			}
++#endif
++			}
++
+ 			if (extract) {
+ 				bfq_check_next_in_service(sd, entity);
+ 				bfq_active_extract(st + i, entity);
+@@ -1070,6 +1298,13 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ 	return entity;
+ }
+ 
++static bool next_queue_may_preempt(struct bfq_data *bfqd)
++{
++	struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
++
++	return sd->next_in_service != sd->in_service_entity;
++}
++
+ /*
+  * Get next queue for service.
+  */
+@@ -1086,7 +1321,36 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
+ 
+ 	sd = &bfqd->root_group->sched_data;
+ 	for (; sd ; sd = entity->my_sched_data) {
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		if (entity) {
++			struct bfq_group *bfqg =
++				container_of(entity, struct bfq_group, entity);
++
++			bfq_log_bfqg(bfqd, bfqg,
++				     "get_next_queue: lookup in this group");
++		} else
++			bfq_log_bfqg(bfqd, bfqd->root_group,
++				     "get_next_queue: lookup in root group");
++#endif
++
+ 		entity = bfq_lookup_next_entity(sd, 1, bfqd);
++
++		bfqq = bfq_entity_to_bfqq(entity);
++		if (bfqq)
++			bfq_log_bfqq(bfqd, bfqq,
++			     "get_next_queue: this queue, finish %llu",
++				(((entity->finish>>10)*1000)>>10)>>2);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++		else {
++			struct bfq_group *bfqg =
++				container_of(entity, struct bfq_group, entity);
++
++			bfq_log_bfqg(bfqd, bfqg,
++			     "get_next_queue: this entity, finish %llu",
++				(((entity->finish>>10)*1000)>>10)>>2);
++		}
++#endif
++
+ 		BUG_ON(!entity);
+ 		entity->service = 0;
+ 	}
+@@ -1113,9 +1377,7 @@ static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ {
+ 	struct bfq_entity *entity = &bfqq->entity;
+ 
+-	if (bfqq == bfqd->in_service_queue)
+-		__bfq_bfqd_reset_in_service(bfqd);
+-
++	BUG_ON(bfqq == bfqd->in_service_queue);
+ 	bfq_deactivate_entity(entity, requeue);
+ }
+ 
+@@ -1123,12 +1385,11 @@ static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ {
+ 	struct bfq_entity *entity = &bfqq->entity;
+ 
+-	bfq_activate_entity(entity);
++	bfq_activate_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq));
++	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
+ }
+ 
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
+-#endif
+ 
+ /*
+  * Called when the bfqq no longer has requests pending, remove it from
+@@ -1139,6 +1400,7 @@ static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ {
+ 	BUG_ON(!bfq_bfqq_busy(bfqq));
+ 	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
++	BUG_ON(bfqq == bfqd->in_service_queue);
+ 
+ 	bfq_log_bfqq(bfqd, bfqq, "del from busy");
+ 
+@@ -1147,27 +1409,20 @@ static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ 	BUG_ON(bfqd->busy_queues == 0);
+ 	bfqd->busy_queues--;
+ 
+-	if (!bfqq->dispatched) {
++	if (!bfqq->dispatched)
+ 		bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ 					&bfqd->queue_weights_tree);
+-		if (!blk_queue_nonrot(bfqd->queue)) {
+-			BUG_ON(!bfqd->busy_in_flight_queues);
+-			bfqd->busy_in_flight_queues--;
+-			if (bfq_bfqq_constantly_seeky(bfqq)) {
+-				BUG_ON(!bfqd->
+-					const_seeky_busy_in_flight_queues);
+-				bfqd->const_seeky_busy_in_flight_queues--;
+-			}
+-		}
+-	}
++
+ 	if (bfqq->wr_coeff > 1)
+ 		bfqd->wr_busy_queues--;
+ 
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	bfqg_stats_update_dequeue(bfqq_group(bfqq));
+-#endif
+ 
++	BUG_ON(bfqq->entity.budget < 0);
++	
+ 	bfq_deactivate_bfqq(bfqd, bfqq, requeue);
++
++	BUG_ON(bfqq->entity.budget < 0);
+ }
+ 
+ /*
+@@ -1185,16 +1440,11 @@ static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+ 	bfq_mark_bfqq_busy(bfqq);
+ 	bfqd->busy_queues++;
+ 
+-	if (!bfqq->dispatched) {
++	if (!bfqq->dispatched)
+ 		if (bfqq->wr_coeff == 1)
+ 			bfq_weights_tree_add(bfqd, &bfqq->entity,
+ 					     &bfqd->queue_weights_tree);
+-		if (!blk_queue_nonrot(bfqd->queue)) {
+-			bfqd->busy_in_flight_queues++;
+-			if (bfq_bfqq_constantly_seeky(bfqq))
+-				bfqd->const_seeky_busy_in_flight_queues++;
+-		}
+-	}
++
+ 	if (bfqq->wr_coeff > 1)
+ 		bfqd->wr_busy_queues++;
+ }
+diff --git a/block/bfq.h b/block/bfq.h
+index f73c942..b8ad02a 100644
+--- a/block/bfq.h
++++ b/block/bfq.h
+@@ -1,5 +1,5 @@
+ /*
+- * BFQ-v7r11 for 4.5.0: data structures and common functions prototypes.
++ * BFQ-v8 for 4.7.0: data structures and common functions prototypes.
+  *
+  * Based on ideas and code from CFQ:
+  * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+@@ -28,7 +28,7 @@
+ 
+ #define BFQ_DEFAULT_QUEUE_IOPRIO	4
+ 
+-#define BFQ_DEFAULT_GRP_WEIGHT	10
++#define BFQ_WEIGHT_LEGACY_DFL	100
+ #define BFQ_DEFAULT_GRP_IOPRIO	0
+ #define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
+ 
+@@ -36,12 +36,6 @@ struct bfq_entity;
+ 
+ /**
+  * struct bfq_service_tree - per ioprio_class service tree.
+- * @active: tree for active entities (i.e., those backlogged).
+- * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i).
+- * @first_idle: idle entity with minimum F_i.
+- * @last_idle: idle entity with maximum F_i.
+- * @vtime: scheduler virtual time.
+- * @wsum: scheduler weight sum; active and idle entities contribute to it.
+  *
+  * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
+  * ioprio_class has its own independent scheduler, and so its own
+@@ -49,27 +43,28 @@ struct bfq_entity;
+  * of the containing bfqd.
+  */
+ struct bfq_service_tree {
++	/* tree for active entities (i.e., those backlogged) */
+ 	struct rb_root active;
++	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
+ 	struct rb_root idle;
+ 
+-	struct bfq_entity *first_idle;
+-	struct bfq_entity *last_idle;
++	struct bfq_entity *first_idle; 	/* idle entity with minimum F_i */
++	struct bfq_entity *last_idle; 	/* idle entity with maximum F_i */
+ 
+-	u64 vtime;
++	u64 vtime; /* scheduler virtual time */
++	/* scheduler weight sum; active and idle entities contribute to it */
+ 	unsigned long wsum;
+ };
+ 
+ /**
+  * struct bfq_sched_data - multi-class scheduler.
+- * @in_service_entity: entity in service.
+- * @next_in_service: head-of-the-line entity in the scheduler.
+- * @service_tree: array of service trees, one per ioprio_class.
+  *
+  * bfq_sched_data is the basic scheduler queue.  It supports three
+- * ioprio_classes, and can be used either as a toplevel queue or as
+- * an intermediate queue on a hierarchical setup.
+- * @next_in_service points to the active entity of the sched_data
+- * service trees that will be scheduled next.
++ * ioprio_classes, and can be used either as a toplevel queue or as an
++ * intermediate queue on a hierarchical setup.  @next_in_service
++ * points to the active entity of the sched_data service trees that
++ * will be scheduled next. It is used to reduce the number of steps
++ * needed for each hierarchical-schedule update.
+  *
+  * The supported ioprio_classes are the same as in CFQ, in descending
+  * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
+@@ -79,48 +74,29 @@ struct bfq_service_tree {
+  * All the fields are protected by the queue lock of the containing bfqd.
+  */
+ struct bfq_sched_data {
+-	struct bfq_entity *in_service_entity;
++	struct bfq_entity *in_service_entity;  /* entity in service */
++	/* head-of-the-line entity in the scheduler (see comments above) */
+ 	struct bfq_entity *next_in_service;
++	/* array of service trees, one per ioprio_class */
+ 	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
+ };
+ 
+ /**
+  * struct bfq_weight_counter - counter of the number of all active entities
+  *                             with a given weight.
+- * @weight: weight of the entities that this counter refers to.
+- * @num_active: number of active entities with this weight.
+- * @weights_node: weights tree member (see bfq_data's @queue_weights_tree
+- *                and @group_weights_tree).
+  */
+ struct bfq_weight_counter {
+-	short int weight;
+-	unsigned int num_active;
++	short int weight; /* weight of the entities this counter refers to */
++	unsigned int num_active; /* nr of active entities with this weight */
++	/*
++	 * Weights tree member (see bfq_data's @queue_weights_tree and
++	 * @group_weights_tree)
++	 */
+ 	struct rb_node weights_node;
+ };
+ 
+ /**
+  * struct bfq_entity - schedulable entity.
+- * @rb_node: service_tree member.
+- * @weight_counter: pointer to the weight counter associated with this entity.
+- * @on_st: flag, true if the entity is on a tree (either the active or
+- *         the idle one of its service_tree).
+- * @finish: B-WF2Q+ finish timestamp (aka F_i).
+- * @start: B-WF2Q+ start timestamp (aka S_i).
+- * @tree: tree the entity is enqueued into; %NULL if not on a tree.
+- * @min_start: minimum start time of the (active) subtree rooted at
+- *             this entity; used for O(log N) lookups into active trees.
+- * @service: service received during the last round of service.
+- * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight.
+- * @weight: weight of the queue
+- * @parent: parent entity, for hierarchical scheduling.
+- * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the
+- *                 associated scheduler queue, %NULL on leaf nodes.
+- * @sched_data: the scheduler queue this entity belongs to.
+- * @ioprio: the ioprio in use.
+- * @new_weight: when a weight change is requested, the new weight value.
+- * @orig_weight: original weight, used to implement weight boosting
+- * @prio_changed: flag, true when the user requested a weight, ioprio or
+- *		  ioprio_class change.
+  *
+  * A bfq_entity is used to represent either a bfq_queue (leaf node in the
+  * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
+@@ -147,27 +123,52 @@ struct bfq_weight_counter {
+  * containing bfqd.
+  */
+ struct bfq_entity {
+-	struct rb_node rb_node;
++	struct rb_node rb_node; /* service_tree member */
++	/* pointer to the weight counter associated with this entity */
+ 	struct bfq_weight_counter *weight_counter;
+ 
++	/*
++	 * flag, true if the entity is on a tree (either the active or
++	 * the idle one of its service_tree).
++	 */
+ 	int on_st;
+ 
+-	u64 finish;
+-	u64 start;
++	u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
++	u64 start;  /* B-WF2Q+ start timestamp (aka S_i) */
+ 
++	/* tree the entity is enqueued into; %NULL if not on a tree */
+ 	struct rb_root *tree;
+ 
++	/*
++	 * minimum start time of the (active) subtree rooted at this
++	 * entity; used for O(log N) lookups into active trees
++	 */
+ 	u64 min_start;
+ 
+-	int service, budget;
+-	unsigned short weight, new_weight;
++	/* amount of service received during the last service slot */
++	int service;
++
++	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
++	int budget;
++
++	unsigned short weight; 	/* weight of the queue */
++	unsigned short new_weight; /* next weight if a change is in progress */
++
++	/* original weight, used to implement weight boosting */
+ 	unsigned short orig_weight;
+ 
++	/* parent entity, for hierarchical scheduling */
+ 	struct bfq_entity *parent;
+ 
++	/*
++	 * For non-leaf nodes in the hierarchy, the associated
++	 * scheduler queue, %NULL on leaf nodes.
++	 */
+ 	struct bfq_sched_data *my_sched_data;
++	/* the scheduler queue this entity belongs to */
+ 	struct bfq_sched_data *sched_data;
+ 
++	/* flag, set to request a weight, ioprio or ioprio_class change  */
+ 	int prio_changed;
+ };
+ 
+@@ -175,56 +176,6 @@ struct bfq_group;
+ 
+ /**
+  * struct bfq_queue - leaf schedulable entity.
+- * @ref: reference counter.
+- * @bfqd: parent bfq_data.
+- * @new_ioprio: when an ioprio change is requested, the new ioprio value.
+- * @ioprio_class: the ioprio_class in use.
+- * @new_ioprio_class: when an ioprio_class change is requested, the new
+- *                    ioprio_class value.
+- * @new_bfqq: shared bfq_queue if queue is cooperating with
+- *           one or more other queues.
+- * @pos_node: request-position tree member (see bfq_group's @rq_pos_tree).
+- * @pos_root: request-position tree root (see bfq_group's @rq_pos_tree).
+- * @sort_list: sorted list of pending requests.
+- * @next_rq: if fifo isn't expired, next request to serve.
+- * @queued: nr of requests queued in @sort_list.
+- * @allocated: currently allocated requests.
+- * @meta_pending: pending metadata requests.
+- * @fifo: fifo list of requests in sort_list.
+- * @entity: entity representing this queue in the scheduler.
+- * @max_budget: maximum budget allowed from the feedback mechanism.
+- * @budget_timeout: budget expiration (in jiffies).
+- * @dispatched: number of requests on the dispatch list or inside driver.
+- * @flags: status flags.
+- * @bfqq_list: node for active/idle bfqq list inside our bfqd.
+- * @burst_list_node: node for the device's burst list.
+- * @seek_samples: number of seeks sampled
+- * @seek_total: sum of the distances of the seeks sampled
+- * @seek_mean: mean seek distance
+- * @last_request_pos: position of the last request enqueued
+- * @requests_within_timer: number of consecutive pairs of request completion
+- *                         and arrival, such that the queue becomes idle
+- *                         after the completion, but the next request arrives
+- *                         within an idle time slice; used only if the queue's
+- *                         IO_bound has been cleared.
+- * @pid: pid of the process owning the queue, used for logging purposes.
+- * @last_wr_start_finish: start time of the current weight-raising period if
+- *                        the @bfq-queue is being weight-raised, otherwise
+- *                        finish time of the last weight-raising period
+- * @wr_cur_max_time: current max raising time for this queue
+- * @soft_rt_next_start: minimum time instant such that, only if a new
+- *                      request is enqueued after this time instant in an
+- *                      idle @bfq_queue with no outstanding requests, then
+- *                      the task associated with the queue it is deemed as
+- *                      soft real-time (see the comments to the function
+- *                      bfq_bfqq_softrt_next_start())
+- * @last_idle_bklogged: time of the last transition of the @bfq_queue from
+- *                      idle to backlogged
+- * @service_from_backlogged: cumulative service received from the @bfq_queue
+- *                           since the last transition from idle to
+- *                           backlogged
+- * @bic: pointer to the bfq_io_cq owning the bfq_queue, set to %NULL if the
+- *	 queue is shared
+  *
+  * A bfq_queue is a leaf request queue; it can be associated with an
+  * io_context or more, if it  is  async or shared  between  cooperating
+@@ -235,117 +186,163 @@ struct bfq_group;
+  * All the fields are protected by the queue lock of the containing bfqd.
+  */
+ struct bfq_queue {
+-	atomic_t ref;
++	/* reference counter */
++	int ref;
++	/* parent bfq_data */
+ 	struct bfq_data *bfqd;
+ 
+-	unsigned short ioprio, new_ioprio;
+-	unsigned short ioprio_class, new_ioprio_class;
++	/* current ioprio and ioprio class */
++	unsigned short ioprio, ioprio_class;
++	/* next ioprio and ioprio class if a change is in progress */
++	unsigned short new_ioprio, new_ioprio_class;
+ 
+-	/* fields for cooperating queues handling */
++	/*
++	 * Shared bfq_queue if queue is cooperating with one or more
++	 * other queues.
++	 */
+ 	struct bfq_queue *new_bfqq;
++	/* request-position tree member (see bfq_group's @rq_pos_tree) */
+ 	struct rb_node pos_node;
++	/* request-position tree root (see bfq_group's @rq_pos_tree) */
+ 	struct rb_root *pos_root;
+ 
++	/* sorted list of pending requests */
+ 	struct rb_root sort_list;
++	/* if fifo isn't expired, next request to serve */
+ 	struct request *next_rq;
++	/* number of sync and async requests queued */
+ 	int queued[2];
++	/* number of sync and async requests currently allocated */
+ 	int allocated[2];
++	/* number of pending metadata requests */
+ 	int meta_pending;
++	/* fifo list of requests in sort_list */
+ 	struct list_head fifo;
+ 
++	/* entity representing this queue in the scheduler */
+ 	struct bfq_entity entity;
+ 
++	/* maximum budget allowed from the feedback mechanism */
+ 	int max_budget;
++	/* budget expiration (in jiffies) */
+ 	unsigned long budget_timeout;
+ 
++	/* number of requests on the dispatch list or inside driver */
+ 	int dispatched;
+ 
+-	unsigned int flags;
++	unsigned int flags; /* status flags.*/
+ 
++	/* node for active/idle bfqq list inside parent bfqd */
+ 	struct list_head bfqq_list;
+ 
++	/* bit vector: a 1 for each seeky requests in history */
++	u32 seek_history;
++
++	/* node for the device's burst list */
+ 	struct hlist_node burst_list_node;
+ 
+-	unsigned int seek_samples;
+-	u64 seek_total;
+-	sector_t seek_mean;
++	/* position of the last request enqueued */
+ 	sector_t last_request_pos;
+ 
++	/* Number of consecutive pairs of request completion and
++	 * arrival, such that the queue becomes idle after the
++	 * completion, but the next request arrives within an idle
++	 * time slice; used only if the queue's IO_bound flag has been
++	 * cleared.
++	 */
+ 	unsigned int requests_within_timer;
+ 
++	/* pid of the process owning the queue, used for logging purposes */
+ 	pid_t pid;
++
++	/*
++	 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
++	 * if the queue is shared.
++	 */
+ 	struct bfq_io_cq *bic;
+ 
+-	/* weight-raising fields */
++	/* current maximum weight-raising time for this queue */
+ 	unsigned long wr_cur_max_time;
++	/*
++	 * Minimum time instant such that, only if a new request is
++	 * enqueued after this time instant in an idle @bfq_queue with
++	 * no outstanding requests, then the task associated with the
++	 * queue it is deemed as soft real-time (see the comments on
++	 * the function bfq_bfqq_softrt_next_start())
++	 */
+ 	unsigned long soft_rt_next_start;
++	/*
++	 * Start time of the current weight-raising period if
++	 * the @bfq-queue is being weight-raised, otherwise
++	 * finish time of the last weight-raising period.
++	 */
+ 	unsigned long last_wr_start_finish;
++	/* factor by which the weight of this queue is multiplied */
+ 	unsigned int wr_coeff;
++	/*
++	 * Time of the last transition of the @bfq_queue from idle to
++	 * backlogged.
++	 */
+ 	unsigned long last_idle_bklogged;
++	/*
++	 * Cumulative service received from the @bfq_queue since the
++	 * last transition from idle to backlogged.
++	 */
+ 	unsigned long service_from_backlogged;
++
++	unsigned long split_time; /* time of last split */
+ };
+ 
+ /**
+  * struct bfq_ttime - per process thinktime stats.
+- * @ttime_total: total process thinktime
+- * @ttime_samples: number of thinktime samples
+- * @ttime_mean: average process thinktime
+  */
+ struct bfq_ttime {
+-	unsigned long last_end_request;
++	unsigned long last_end_request; /* completion time of last request */
++
++	unsigned long ttime_total; /* total process thinktime */
++	unsigned long ttime_samples; /* number of thinktime samples */
++	unsigned long ttime_mean; /* average process thinktime */
+ 
+-	unsigned long ttime_total;
+-	unsigned long ttime_samples;
+-	unsigned long ttime_mean;
+ };
+ 
+ /**
+  * struct bfq_io_cq - per (request_queue, io_context) structure.
+- * @icq: associated io_cq structure
+- * @bfqq: array of two process queues, the sync and the async
+- * @ttime: associated @bfq_ttime struct
+- * @ioprio: per (request_queue, blkcg) ioprio.
+- * @blkcg_id: id of the blkcg the related io_cq belongs to.
+- * @wr_time_left: snapshot of the time left before weight raising ends
+- *                for the sync queue associated to this process; this
+- *		  snapshot is taken to remember this value while the weight
+- *		  raising is suspended because the queue is merged with a
+- *		  shared queue, and is used to set @raising_cur_max_time
+- *		  when the queue is split from the shared queue and its
+- *		  weight is raised again
+- * @saved_idle_window: same purpose as the previous field for the idle
+- *                     window
+- * @saved_IO_bound: same purpose as the previous two fields for the I/O
+- *                  bound classification of a queue
+- * @saved_in_large_burst: same purpose as the previous fields for the
+- *                        value of the field keeping the queue's belonging
+- *                        to a large burst
+- * @was_in_burst_list: true if the queue belonged to a burst list
+- *                     before its merge with another cooperating queue
+- * @cooperations: counter of consecutive successful queue merges underwent
+- *                by any of the process' @bfq_queues
+- * @failed_cooperations: counter of consecutive failed queue merges of any
+- *                       of the process' @bfq_queues
+  */
+ struct bfq_io_cq {
++	/* associated io_cq structure */
+ 	struct io_cq icq; /* must be the first member */
++	/* array of two process queues, the sync and the async */
+ 	struct bfq_queue *bfqq[2];
++	/* associated @bfq_ttime struct */
+ 	struct bfq_ttime ttime;
++	/* per (request_queue, blkcg) ioprio */
+ 	int ioprio;
+-
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+-	uint64_t blkcg_id; /* the current blkcg ID */
++	uint64_t blkcg_serial_nr; /* the current blkcg serial */
+ #endif
+ 
+-	unsigned int wr_time_left;
++	/*
++	 * Snapshot of the idle window before merging; taken to
++	 * remember this value while the queue is merged, so as to be
++	 * able to restore it in case of split.
++	 */
+ 	bool saved_idle_window;
++	/*
++	 * Same purpose as the previous two fields for the I/O bound
++	 * classification of a queue.
++	 */
+ 	bool saved_IO_bound;
+ 
++	/*
++	 * Same purpose as the previous fields for the value of the
++	 * field keeping the queue's belonging to a large burst
++	 */
+ 	bool saved_in_large_burst;
++	/*
++	 * True if the queue belonged to a burst list before its merge
++	 * with another cooperating queue.
++	 */
+ 	bool was_in_burst_list;
+-
+-	unsigned int cooperations;
+-	unsigned int failed_cooperations;
+ };
+ 
+ enum bfq_device_speed {
+@@ -354,224 +351,216 @@ enum bfq_device_speed {
+ };
+ 
+ /**
+- * struct bfq_data - per device data structure.
+- * @queue: request queue for the managed device.
+- * @root_group: root bfq_group for the device.
+- * @active_numerous_groups: number of bfq_groups containing more than one
+- *                          active @bfq_entity.
+- * @queue_weights_tree: rbtree of weight counters of @bfq_queues, sorted by
+- *                      weight. Used to keep track of whether all @bfq_queues
+- *                     have the same weight. The tree contains one counter
+- *                     for each distinct weight associated to some active
+- *                     and not weight-raised @bfq_queue (see the comments to
+- *                      the functions bfq_weights_tree_[add|remove] for
+- *                     further details).
+- * @group_weights_tree: rbtree of non-queue @bfq_entity weight counters, sorted
+- *                      by weight. Used to keep track of whether all
+- *                     @bfq_groups have the same weight. The tree contains
+- *                     one counter for each distinct weight associated to
+- *                     some active @bfq_group (see the comments to the
+- *                     functions bfq_weights_tree_[add|remove] for further
+- *                     details).
+- * @busy_queues: number of bfq_queues containing requests (including the
+- *		 queue in service, even if it is idling).
+- * @busy_in_flight_queues: number of @bfq_queues containing pending or
+- *                         in-flight requests, plus the @bfq_queue in
+- *                         service, even if idle but waiting for the
+- *                         possible arrival of its next sync request. This
+- *                         field is updated only if the device is rotational,
+- *                         but used only if the device is also NCQ-capable.
+- *                         The reason why the field is updated also for non-
+- *                         NCQ-capable rotational devices is related to the
+- *                         fact that the value of @hw_tag may be set also
+- *                         later than when busy_in_flight_queues may need to
+- *                         be incremented for the first time(s). Taking also
+- *                         this possibility into account, to avoid unbalanced
+- *                         increments/decrements, would imply more overhead
+- *                         than just updating busy_in_flight_queues
+- *                         regardless of the value of @hw_tag.
+- * @const_seeky_busy_in_flight_queues: number of constantly-seeky @bfq_queues
+- *                                     (that is, seeky queues that expired
+- *                                     for budget timeout at least once)
+- *                                     containing pending or in-flight
+- *                                     requests, including the in-service
+- *                                     @bfq_queue if constantly seeky. This
+- *                                     field is updated only if the device
+- *                                     is rotational, but used only if the
+- *                                     device is also NCQ-capable (see the
+- *                                     comments to @busy_in_flight_queues).
+- * @wr_busy_queues: number of weight-raised busy @bfq_queues.
+- * @queued: number of queued requests.
+- * @rq_in_driver: number of requests dispatched and waiting for completion.
+- * @sync_flight: number of sync requests in the driver.
+- * @max_rq_in_driver: max number of reqs in driver in the last
+- *                    @hw_tag_samples completed requests.
+- * @hw_tag_samples: nr of samples used to calculate hw_tag.
+- * @hw_tag: flag set to one if the driver is showing a queueing behavior.
+- * @budgets_assigned: number of budgets assigned.
+- * @idle_slice_timer: timer set when idling for the next sequential request
+- *                    from the queue in service.
+- * @unplug_work: delayed work to restart dispatching on the request queue.
+- * @in_service_queue: bfq_queue in service.
+- * @in_service_bic: bfq_io_cq (bic) associated with the @in_service_queue.
+- * @last_position: on-disk position of the last served request.
+- * @last_budget_start: beginning of the last budget.
+- * @last_idling_start: beginning of the last idle slice.
+- * @peak_rate: peak transfer rate observed for a budget.
+- * @peak_rate_samples: number of samples used to calculate @peak_rate.
+- * @bfq_max_budget: maximum budget allotted to a bfq_queue before
+- *                  rescheduling.
+- * @active_list: list of all the bfq_queues active on the device.
+- * @idle_list: list of all the bfq_queues idle on the device.
+- * @bfq_fifo_expire: timeout for async/sync requests; when it expires
+- *                   requests are served in fifo order.
+- * @bfq_back_penalty: weight of backward seeks wrt forward ones.
+- * @bfq_back_max: maximum allowed backward seek.
+- * @bfq_slice_idle: maximum idling time.
+- * @bfq_user_max_budget: user-configured max budget value
+- *                       (0 for auto-tuning).
+- * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to
+- *                           async queues.
+- * @bfq_timeout: timeout for bfq_queues to consume their budget; used to
+- *               to prevent seeky queues to impose long latencies to well
+- *               behaved ones (this also implies that seeky queues cannot
+- *               receive guarantees in the service domain; after a timeout
+- *               they are charged for the whole allocated budget, to try
+- *               to preserve a behavior reasonably fair among them, but
+- *               without service-domain guarantees).
+- * @bfq_coop_thresh: number of queue merges after which a @bfq_queue is
+- *                   no more granted any weight-raising.
+- * @bfq_failed_cooperations: number of consecutive failed cooperation
+- *                           chances after which weight-raising is restored
+- *                           to a queue subject to more than bfq_coop_thresh
+- *                           queue merges.
+- * @bfq_requests_within_timer: number of consecutive requests that must be
+- *                             issued within the idle time slice to set
+- *                             again idling to a queue which was marked as
+- *                             non-I/O-bound (see the definition of the
+- *                             IO_bound flag for further details).
+- * @last_ins_in_burst: last time at which a queue entered the current
+- *                     burst of queues being activated shortly after
+- *                     each other; for more details about this and the
+- *                     following parameters related to a burst of
+- *                     activations, see the comments to the function
+- *                     @bfq_handle_burst.
+- * @bfq_burst_interval: reference time interval used to decide whether a
+- *                      queue has been activated shortly after
+- *                      @last_ins_in_burst.
+- * @burst_size: number of queues in the current burst of queue activations.
+- * @bfq_large_burst_thresh: maximum burst size above which the current
+- * 			    queue-activation burst is deemed as 'large'.
+- * @large_burst: true if a large queue-activation burst is in progress.
+- * @burst_list: head of the burst list (as for the above fields, more details
+- * 		in the comments to the function bfq_handle_burst).
+- * @low_latency: if set to true, low-latency heuristics are enabled.
+- * @bfq_wr_coeff: maximum factor by which the weight of a weight-raised
+- *                queue is multiplied.
+- * @bfq_wr_max_time: maximum duration of a weight-raising period (jiffies).
+- * @bfq_wr_rt_max_time: maximum duration for soft real-time processes.
+- * @bfq_wr_min_idle_time: minimum idle period after which weight-raising
+- *			  may be reactivated for a queue (in jiffies).
+- * @bfq_wr_min_inter_arr_async: minimum period between request arrivals
+- *				after which weight-raising may be
+- *				reactivated for an already busy queue
+- *				(in jiffies).
+- * @bfq_wr_max_softrt_rate: max service-rate for a soft real-time queue,
+- *			    sectors per seconds.
+- * @RT_prod: cached value of the product R*T used for computing the maximum
+- *	     duration of the weight raising automatically.
+- * @device_speed: device-speed class for the low-latency heuristic.
+- * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions.
++ * struct bfq_data - per-device data structure.
+  *
+  * All the fields are protected by the @queue lock.
+  */
+ struct bfq_data {
++	/* request queue for the device */
+ 	struct request_queue *queue;
+ 
++	/* root bfq_group for the device */
+ 	struct bfq_group *root_group;
+ 
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+-	int active_numerous_groups;
+-#endif
+-
++	/*
++	 * rbtree of weight counters of @bfq_queues, sorted by
++	 * weight. Used to keep track of whether all @bfq_queues have
++	 * the same weight. The tree contains one counter for each
++	 * distinct weight associated to some active and not
++	 * weight-raised @bfq_queue (see the comments to the functions
++	 * bfq_weights_tree_[add|remove] for further details).
++	 */
+ 	struct rb_root queue_weights_tree;
++	/*
++	 * rbtree of non-queue @bfq_entity weight counters, sorted by
++	 * weight. Used to keep track of whether all @bfq_groups have
++	 * the same weight. The tree contains one counter for each
++	 * distinct weight associated to some active @bfq_group (see
++	 * the comments to the functions bfq_weights_tree_[add|remove]
++	 * for further details).
++	 */
+ 	struct rb_root group_weights_tree;
+ 
++	/*
++	 * Number of bfq_queues containing requests (including the
++	 * queue in service, even if it is idling).
++	 */
+ 	int busy_queues;
+-	int busy_in_flight_queues;
+-	int const_seeky_busy_in_flight_queues;
++	/* number of weight-raised busy @bfq_queues */
+ 	int wr_busy_queues;
++	/* number of queued requests */
+ 	int queued;
++	/* number of requests dispatched and waiting for completion */
+ 	int rq_in_driver;
+-	int sync_flight;
+ 
++	/*
++	 * Maximum number of requests in driver in the last
++	 * @hw_tag_samples completed requests.
++	 */
+ 	int max_rq_in_driver;
++	/* number of samples used to calculate hw_tag */
+ 	int hw_tag_samples;
++	/* flag set to one if the driver is showing a queueing behavior */
+ 	int hw_tag;
+ 
++	/* number of budgets assigned */
+ 	int budgets_assigned;
+ 
++	/*
++	 * Timer set when idling (waiting) for the next request from
++	 * the queue in service.
++	 */
+ 	struct timer_list idle_slice_timer;
++	/* delayed work to restart dispatching on the request queue */
+ 	struct work_struct unplug_work;
+ 
++	/* bfq_queue in service */
+ 	struct bfq_queue *in_service_queue;
++	/* bfq_io_cq (bic) associated with the @in_service_queue */
+ 	struct bfq_io_cq *in_service_bic;
+ 
++	/* on-disk position of the last served request */
+ 	sector_t last_position;
+ 
++	/* beginning of the last budget */
+ 	ktime_t last_budget_start;
++	/* beginning of the last idle slice */
+ 	ktime_t last_idling_start;
++	/* number of samples used to calculate @peak_rate */
+ 	int peak_rate_samples;
++	/* peak transfer rate observed for a budget */
+ 	u64 peak_rate;
++	/* maximum budget allotted to a bfq_queue before rescheduling */
+ 	int bfq_max_budget;
+ 
++	/* list of all the bfq_queues active on the device */
+ 	struct list_head active_list;
++	/* list of all the bfq_queues idle on the device */
+ 	struct list_head idle_list;
+ 
++	/*
++	 * Timeout for async/sync requests; when it fires, requests
++	 * are served in fifo order.
++	 */
+ 	unsigned int bfq_fifo_expire[2];
++	/* weight of backward seeks wrt forward ones */
+ 	unsigned int bfq_back_penalty;
++	/* maximum allowed backward seek */
+ 	unsigned int bfq_back_max;
++	/* maximum idling time */
+ 	unsigned int bfq_slice_idle;
++	/* last time CLASS_IDLE was served */
+ 	u64 bfq_class_idle_last_service;
+ 
++	/* user-configured max budget value (0 for auto-tuning) */
+ 	int bfq_user_max_budget;
+-	int bfq_max_budget_async_rq;
+-	unsigned int bfq_timeout[2];
+-
+-	unsigned int bfq_coop_thresh;
+-	unsigned int bfq_failed_cooperations;
++	/*
++	 * Timeout for bfq_queues to consume their budget; used to
++	 * prevent seeky queues from imposing long latencies to
++	 * sequential or quasi-sequential ones (this also implies that
++	 * seeky queues cannot receive guarantees in the service
++	 * domain; after a timeout they are charged for the time they
++	 * have been in service, to preserve fairness among them, but
++	 * without service-domain guarantees).
++	 */
++	unsigned int bfq_timeout;
++
++	/*
++	 * Number of consecutive requests that must be issued within
++	 * the idle time slice to set again idling to a queue which
++	 * was marked as non-I/O-bound (see the definition of the
++	 * IO_bound flag for further details).
++	 */
+ 	unsigned int bfq_requests_within_timer;
+ 
++	/*
++	 * Force device idling whenever needed to provide accurate
++	 * service guarantees, without caring about throughput
++	 * issues. CAVEAT: this may even increase latencies, in case
++	 * of useless idling for processes that did stop doing I/O.
++	 */
++	bool strict_guarantees;
++
++	/*
++	 * Last time at which a queue entered the current burst of
++	 * queues being activated shortly after each other; for more
++	 * details about this and the following parameters related to
++	 * a burst of activations, see the comments on the function
++	 * bfq_handle_burst.
++	 */
+ 	unsigned long last_ins_in_burst;
++	/*
++	 * Reference time interval used to decide whether a queue has
++	 * been activated shortly after @last_ins_in_burst.
++	 */
+ 	unsigned long bfq_burst_interval;
++	/* number of queues in the current burst of queue activations */
+ 	int burst_size;
++
++	/* common parent entity for the queues in the burst */
++	struct bfq_entity *burst_parent_entity;
++	/* Maximum burst size above which the current queue-activation
++	 * burst is deemed as 'large'.
++	 */
+ 	unsigned long bfq_large_burst_thresh;
++	/* true if a large queue-activation burst is in progress */
+ 	bool large_burst;
++	/*
++	 * Head of the burst list (as for the above fields, more
++	 * details in the comments on the function bfq_handle_burst).
++	 */
+ 	struct hlist_head burst_list;
+ 
++	/* if set to true, low-latency heuristics are enabled */
+ 	bool low_latency;
+-
+-	/* parameters of the low_latency heuristics */
++	/*
++	 * Maximum factor by which the weight of a weight-raised queue
++	 * is multiplied.
++	 */
+ 	unsigned int bfq_wr_coeff;
++	/* maximum duration of a weight-raising period (jiffies) */
+ 	unsigned int bfq_wr_max_time;
++
++	/* Maximum weight-raising duration for soft real-time processes */
+ 	unsigned int bfq_wr_rt_max_time;
++	/*
++	 * Minimum idle period after which weight-raising may be
++	 * reactivated for a queue (in jiffies).
++	 */
+ 	unsigned int bfq_wr_min_idle_time;
++	/*
++	 * Minimum period between request arrivals after which
++	 * weight-raising may be reactivated for an already busy async
++	 * queue (in jiffies).
++	 */
+ 	unsigned long bfq_wr_min_inter_arr_async;
++
++	/* Max service-rate for a soft real-time queue, in sectors/sec */
+ 	unsigned int bfq_wr_max_softrt_rate;
++	/*
++	 * Cached value of the product R*T, used for computing the
++	 * maximum duration of weight raising automatically.
++	 */
+ 	u64 RT_prod;
++	/* device-speed class for the low-latency heuristic */
+ 	enum bfq_device_speed device_speed;
+ 
++	/* fallback dummy bfqq for extreme OOM conditions */
+ 	struct bfq_queue oom_bfqq;
+ };
+ 
+ enum bfqq_state_flags {
+-	BFQ_BFQQ_FLAG_busy = 0,		/* has requests or is in service */
++	BFQ_BFQQ_FLAG_just_created = 0,	/* queue just allocated */
++	BFQ_BFQQ_FLAG_busy,		/* has requests or is in service */
+ 	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
++	BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
++					     * waiting for a request
++					     * without idling the device
++					     */
+ 	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
+ 	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
+ 	BFQ_BFQQ_FLAG_idle_window,	/* slice idling enabled */
+ 	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
+-	BFQ_BFQQ_FLAG_budget_new,	/* no completion with this budget */
+ 	BFQ_BFQQ_FLAG_IO_bound,		/*
+ 					 * bfqq has timed-out at least once
+ 					 * having consumed at most 2/10 of
+@@ -581,17 +570,12 @@ enum bfqq_state_flags {
+ 					 * bfqq activated in a large burst,
+ 					 * see comments to bfq_handle_burst.
+ 					 */
+-	BFQ_BFQQ_FLAG_constantly_seeky,	/*
+-					 * bfqq has proved to be slow and
+-					 * seeky until budget timeout
+-					 */
+ 	BFQ_BFQQ_FLAG_softrt_update,	/*
+ 					 * may need softrt-next-start
+ 					 * update
+ 					 */
+ 	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
+-	BFQ_BFQQ_FLAG_split_coop,	/* shared bfqq will be split */
+-	BFQ_BFQQ_FLAG_just_split,	/* queue has just been split */
++	BFQ_BFQQ_FLAG_split_coop	/* shared bfqq will be split */
+ };
+ 
+ #define BFQ_BFQQ_FNS(name)						\
+@@ -608,25 +592,53 @@ static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
+ 	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
+ }
+ 
++BFQ_BFQQ_FNS(just_created);
+ BFQ_BFQQ_FNS(busy);
+ BFQ_BFQQ_FNS(wait_request);
++BFQ_BFQQ_FNS(non_blocking_wait_rq);
+ BFQ_BFQQ_FNS(must_alloc);
+ BFQ_BFQQ_FNS(fifo_expire);
+ BFQ_BFQQ_FNS(idle_window);
+ BFQ_BFQQ_FNS(sync);
+-BFQ_BFQQ_FNS(budget_new);
+ BFQ_BFQQ_FNS(IO_bound);
+ BFQ_BFQQ_FNS(in_large_burst);
+-BFQ_BFQQ_FNS(constantly_seeky);
+ BFQ_BFQQ_FNS(coop);
+ BFQ_BFQQ_FNS(split_coop);
+-BFQ_BFQQ_FNS(just_split);
+ BFQ_BFQQ_FNS(softrt_update);
+ #undef BFQ_BFQQ_FNS
+ 
+ /* Logging facilities. */
+-#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
+-	blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args)
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
++static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
++
++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
++	char __pbuf[128];						\
++									\
++	assert_spin_locked((bfqd)->queue->queue_lock);			\
++	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
++	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
++			  (bfqq)->pid,			  \
++			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
++			  __pbuf, ##args);				\
++} while (0)
++
++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
++	char __pbuf[128];						\
++									\
++	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
++	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
++} while (0)
++
++#else /* CONFIG_BFQ_GROUP_IOSCHED */
++
++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
++	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
++			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
++				##args)
++#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
++
++#endif /* CONFIG_BFQ_GROUP_IOSCHED */
+ 
+ #define bfq_log(bfqd, fmt, args...) \
+ 	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
+@@ -640,15 +652,12 @@ enum bfqq_expiration {
+ 	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
+ 	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
+ 	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
++	BFQ_BFQQ_PREEMPTED		/* preemption in progress */
+ };
+ 
+-#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 
+ struct bfqg_stats {
+-	/* total bytes transferred */
+-	struct blkg_rwstat		service_bytes;
+-	/* total IOs serviced, post merge */
+-	struct blkg_rwstat		serviced;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 	/* number of ios merged */
+ 	struct blkg_rwstat		merged;
+ 	/* total time spent on device in ns, may not be accurate w/ queueing */
+@@ -657,12 +666,8 @@ struct bfqg_stats {
+ 	struct blkg_rwstat		wait_time;
+ 	/* number of IOs queued up */
+ 	struct blkg_rwstat		queued;
+-	/* total sectors transferred */
+-	struct blkg_stat		sectors;
+ 	/* total disk time and nr sectors dispatched by this group */
+ 	struct blkg_stat		time;
+-	/* time not charged to this cgroup */
+-	struct blkg_stat		unaccounted_time;
+ 	/* sum of number of ios queued across all samples */
+ 	struct blkg_stat		avg_queue_size_sum;
+ 	/* count of samples taken for average */
+@@ -680,8 +685,10 @@ struct bfqg_stats {
+ 	uint64_t			start_idle_time;
+ 	uint64_t			start_empty_time;
+ 	uint16_t			flags;
++#endif
+ };
+ 
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ /*
+  * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
+  *
+@@ -712,7 +719,7 @@ struct bfq_group_data {
+  *                   unused for the root group. Used to know whether there
+  *                   are groups with more than one active @bfq_entity
+  *                   (see the comments to the function
+- *                   bfq_bfqq_must_not_expire()).
++ *                   bfq_bfqq_may_idle()).
+  * @rq_pos_tree: rbtree sorted by next_request position, used when
+  *               determining if two or more queues have interleaving
+  *               requests (see bfq_find_close_cooperator()).
+@@ -745,7 +752,6 @@ struct bfq_group {
+ 	struct rb_root rq_pos_tree;
+ 
+ 	struct bfqg_stats stats;
+-	struct bfqg_stats dead_stats;	/* stats pushed from dead children */
+ };
+ 
+ #else
+@@ -767,11 +773,25 @@ bfq_entity_service_tree(struct bfq_entity *entity)
+ 	struct bfq_sched_data *sched_data = entity->sched_data;
+ 	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ 	unsigned int idx = bfqq ? bfqq->ioprio_class - 1 :
+-				  BFQ_DEFAULT_GRP_CLASS;
++				  BFQ_DEFAULT_GRP_CLASS - 1;
+ 
+ 	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
+ 	BUG_ON(sched_data == NULL);
+ 
++	if (bfqq)
++		bfq_log_bfqq(bfqq->bfqd, bfqq,
++			     "entity_service_tree %p %d",
++			     sched_data->service_tree + idx, idx) ;
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
++	else {
++		struct bfq_group *bfqg =
++			container_of(entity, struct bfq_group, entity);
++
++		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
++			     "entity_service_tree %p %d",
++			     sched_data->service_tree + idx, idx) ;
++	}
++#endif
+ 	return sched_data->service_tree + idx;
+ }
+ 
+@@ -791,47 +811,6 @@ static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
+ 	return bic->icq.q->elevator->elevator_data;
+ }
+ 
+-/**
+- * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer.
+- * @ptr: a pointer to a bfqd.
+- * @flags: storage for the flags to be saved.
+- *
+- * This function allows bfqg->bfqd to be protected by the
+- * queue lock of the bfqd they reference; the pointer is dereferenced
+- * under RCU, so the storage for bfqd is assured to be safe as long
+- * as the RCU read side critical section does not end.  After the
+- * bfqd->queue->queue_lock is taken the pointer is rechecked, to be
+- * sure that no other writer accessed it.  If we raced with a writer,
+- * the function returns NULL, with the queue unlocked, otherwise it
+- * returns the dereferenced pointer, with the queue locked.
+- */
+-static struct bfq_data *bfq_get_bfqd_locked(void **ptr, unsigned long *flags)
+-{
+-	struct bfq_data *bfqd;
+-
+-	rcu_read_lock();
+-	bfqd = rcu_dereference(*(struct bfq_data **)ptr);
+-
+-	if (bfqd != NULL) {
+-		spin_lock_irqsave(bfqd->queue->queue_lock, *flags);
+-		if (ptr == NULL)
+-			printk(KERN_CRIT "get_bfqd_locked pointer NULL\n");
+-		else if (*ptr == bfqd)
+-			goto out;
+-		spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+-	}
+-
+-	bfqd = NULL;
+-out:
+-	rcu_read_unlock();
+-	return bfqd;
+-}
+-
+-static void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags)
+-{
+-	spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+-}
+-
+ #ifdef CONFIG_BFQ_GROUP_IOSCHED
+ 
+ static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
+@@ -857,11 +836,13 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
+ static void bfq_put_queue(struct bfq_queue *bfqq);
+ static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
+ static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+-				       struct bio *bio, int is_sync,
+-				       struct bfq_io_cq *bic, gfp_t gfp_mask);
++				       struct bio *bio, bool is_sync,
++				       struct bfq_io_cq *bic);
+ static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+ 				    struct bfq_group *bfqg);
++#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
++#endif
+ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+ 
+ #endif /* _BFQ_H */
+-- 
+1.9.1
+