Merge branch 'for-4.3/blkcg' of git://git.kernel.dk/linux-block

Pull blk-cg updates from Jens Axboe:
 "A bit later in the cycle, but this has been in the block tree for a a
  while.  This is basically four patchsets from Tejun, that improve our
  buffered cgroup writeback.  It was dependent on the other cgroup
  changes, but they went in earlier in this cycle.

  Series 1 is set of 5 patches that has cgroup writeback updates:

   - bdi_writeback iteration fix which could lead to some wb's being
     skipped or repeated during e.g. sync under memory pressure.

   - Simplification of wb work wait mechanism.

   - Writeback tracepoints updated to report cgroup.

  Series 2 is is a set of updates for the CFQ cgroup writeback handling:

     cfq has always charged all async IOs to the root cgroup.  It didn't
     have much choice as writeback didn't know about cgroups and there
     was no way to tell who to blame for a given writeback IO.
     writeback finally grew support for cgroups and now tags each
     writeback IO with the appropriate cgroup to charge it against.

     This patchset updates cfq so that it follows the blkcg each bio is
     tagged with.  Async cfq_queues are now shared across cfq_group,
     which is per-cgroup, instead of per-request_queue cfq_data.  This
     makes all IOs follow the weight based IO resource distribution
     implemented by cfq.

     - Switched from GFP_ATOMIC to GFP_NOWAIT as suggested by Jeff.

     - Other misc review points addressed, acks added and rebased.

  Series 3 is the blkcg policy cleanup patches:

     This patchset contains assorted cleanups for blkcg_policy methods
     and blk[c]g_policy_data handling.

     - alloc/free added for blkg_policy_data.  exit dropped.

     - alloc/free added for blkcg_policy_data.

     - blk-throttle's async percpu allocation is replaced with direct
       allocation.

     - all methods now take blk[c]g_policy_data instead of blkcg_gq or
       blkcg.

  And finally, series 4 is a set of patches cleaning up the blkcg stats
  handling:

    blkcg's stats have always been somwhat of a mess.  This patchset
    tries to improve the situation a bit.

     - The following patches added to consolidate blkcg entry point and
       blkg creation.  This is in itself is an improvement and helps
       colllecting common stats on bio issue.

     - per-blkg stats now accounted on bio issue rather than request
       completion so that bio based and request based drivers can behave
       the same way.  The issue was spotted by Vivek.

     - cfq-iosched implements custom recursive stats and blk-throttle
       implements custom per-cpu stats.  This patchset make blkcg core
       support both by default.

     - cfq-iosched and blk-throttle keep track of the same stats
       multiple times.  Unify them"

* 'for-4.3/blkcg' of git://git.kernel.dk/linux-block: (45 commits)
  blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchy
  blkcg: s/CFQ_WEIGHT_*/CFQ_WEIGHT_LEGACY_*/
  blkcg: implement interface for the unified hierarchy
  blkcg: misc preparations for unified hierarchy interface
  blkcg: separate out tg_conf_updated() from tg_set_conf()
  blkcg: move body parsing from blkg_conf_prep() to its callers
  blkcg: mark existing cftypes as legacy
  blkcg: rename subsystem name from blkio to io
  blkcg: refine error codes returned during blkcg configuration
  blkcg: remove unnecessary NULL checks from __cfqg_set_weight_device()
  blkcg: reduce stack usage of blkg_rwstat_recursive_sum()
  blkcg: remove cfqg_stats->sectors
  blkcg: move io_service_bytes and io_serviced stats into blkcg_gq
  blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq
  blkcg: make blkcg_[rw]stat per-cpu
  blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it
  blkcg: consolidate blkg creation in blkcg_bio_issue_check()
  blk-throttle: improve queue bypass handling
  blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup()
  blkcg: inline [__]blkg_lookup()
  ...

Documentation/cgroups/blkio-controller.txt

@@ -201,7 +201,7 @@ Proportional weight policy files
 	  specifies the number of bytes.
 
 - blkio.io_serviced
-	- Number of IOs completed to/from the disk by the group. These
+	- Number of IOs (bio) issued to the disk by the group. These
 	  are further divided by the type of operation - read or write, sync
 	  or async. First two fields specify the major and minor number of the
 	  device, third field specifies the operation type and the fourth field
@@ -327,18 +327,11 @@ Note: If both BW and IOPS rules are specified for a device, then IO is
       subjected to both the constraints.
 
 - blkio.throttle.io_serviced
-	- Number of IOs (bio) completed to/from the disk by the group (as
-	  seen by throttling policy). These are further divided by the type
-	  of operation - read or write, sync or async. First two fields specify
-	  the major and minor number of the device, third field specifies the
-	  operation type and the fourth field specifies the number of IOs.
-
-	  blkio.io_serviced does accounting as seen by CFQ and counts are in
-	  number of requests (struct request). On the other hand,
-	  blkio.throttle.io_serviced counts number of IO in terms of number
-	  of bios as seen by throttling policy.  These bios can later be
-	  merged by elevator and total number of requests completed can be
-	  lesser.
+	- Number of IOs (bio) issued to the disk by the group. These
+	  are further divided by the type of operation - read or write, sync
+	  or async. First two fields specify the major and minor number of the
+	  device, third field specifies the operation type and the fourth field
+	  specifies the number of IOs.
 
 - blkio.throttle.io_service_bytes
 	- Number of bytes transferred to/from the disk by the group. These
@@ -347,11 +340,6 @@ Note: If both BW and IOPS rules are specified for a device, then IO is
 	  device, third field specifies the operation type and the fourth field
 	  specifies the number of bytes.
 
-	  These numbers should roughly be same as blkio.io_service_bytes as
-	  updated by CFQ. The difference between two is that
-	  blkio.io_service_bytes will not be updated if CFQ is not operating
-	  on request queue.
-
 Common files among various policies
 -----------------------------------
 - blkio.reset_stats

Documentation/cgroups/unified-hierarchy.txt

@@ -27,7 +27,7 @@ CONTENTS
     5-3-1. Format
     5-3-2. Control Knobs
   5-4. Per-Controller Changes
-    5-4-1. blkio
+    5-4-1. io
     5-4-2. cpuset
     5-4-3. memory
 6. Planned Changes
@@ -203,7 +203,7 @@ other issues.  The mapping from nice level to weight isn't obvious or
 universal, and there are various other knobs which simply aren't
 available for tasks.
 
-The blkio controller implicitly creates a hidden leaf node for each
+The io controller implicitly creates a hidden leaf node for each
 cgroup to host the tasks.  The hidden leaf has its own copies of all
 the knobs with "leaf_" prefixed.  While this allows equivalent control
 over internal tasks, it's with serious drawbacks.  It always adds an
@@ -438,9 +438,62 @@ may be specified in any order and not all pairs have to be specified.
 
 5-4. Per-Controller Changes
 
-5-4-1. blkio
+5-4-1. io
 
-- blk-throttle becomes properly hierarchical.
+- blkio is renamed to io.  The interface is overhauled anyway.  The
+  new name is more in line with the other two major controllers, cpu
+  and memory, and better suited given that it may be used for cgroup
+  writeback without involving block layer.
+
+- Everything including stat is always hierarchical making separate
+  recursive stat files pointless and, as no internal node can have
+  tasks, leaf weights are meaningless.  The operation model is
+  simplified and the interface is overhauled accordingly.
+
+  io.stat
+
+	The stat file.  The reported stats are from the point where
+	bio's are issued to request_queue.  The stats are counted
+	independent of which policies are enabled.  Each line in the
+	file follows the following format.  More fields may later be
+	added at the end.
+
+	  $MAJ:$MIN rbytes=$RBYTES wbytes=$WBYTES rios=$RIOS wrios=$WIOS
+
+  io.weight
+
+	The weight setting, currently only available and effective if
+	cfq-iosched is in use for the target device.  The weight is
+	between 1 and 10000 and defaults to 100.  The first line
+	always contains the default weight in the following format to
+	use when per-device setting is missing.
+
+	  default $WEIGHT
+
+	Subsequent lines list per-device weights of the following
+	format.
+
+	  $MAJ:$MIN $WEIGHT
+
+	Writing "$WEIGHT" or "default $WEIGHT" changes the default
+	setting.  Writing "$MAJ:$MIN $WEIGHT" sets per-device weight
+	while "$MAJ:$MIN default" clears it.
+
+	This file is available only on non-root cgroups.
+
+  io.max
+
+	The maximum bandwidth and/or iops setting, only available if
+	blk-throttle is enabled.  The file is of the following format.
+
+	  $MAJ:$MIN rbps=$RBPS wbps=$WBPS riops=$RIOPS wiops=$WIOPS
+
+	${R|W}BPS are read/write bytes per second and ${R|W}IOPS are
+	read/write IOs per second.  "max" indicates no limit.  Writing
+	to the file follows the same format but the individual
+	settings may be ommitted or specified in any order.
+
+	This file is available only on non-root cgroups.
 
 
 5-4-2. cpuset

block/bio.c

@@ -1990,7 +1990,7 @@ int bio_associate_current(struct bio *bio)
 
 	get_io_context_active(ioc);
 	bio->bi_ioc = ioc;
-	bio->bi_css = task_get_css(current, blkio_cgrp_id);
+	bio->bi_css = task_get_css(current, io_cgrp_id);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(bio_associate_current);

block/blk-cgroup.c

@@ -24,6 +24,7 @@
 #include <linux/genhd.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
+#include <linux/ctype.h>
 #include <linux/blk-cgroup.h>
 #include "blk.h"
 
@@ -68,9 +69,14 @@ static void blkg_free(struct blkcg_gq *blkg)
 		return;
 
 	for (i = 0; i < BLKCG_MAX_POLS; i++)
-		kfree(blkg->pd[i]);
+		if (blkg->pd[i])
+			blkcg_policy[i]->pd_free_fn(blkg->pd[i]);
 
-	blk_exit_rl(&blkg->rl);
+	if (blkg->blkcg != &blkcg_root)
+		blk_exit_rl(&blkg->rl);
+
+	blkg_rwstat_exit(&blkg->stat_ios);
+	blkg_rwstat_exit(&blkg->stat_bytes);
 	kfree(blkg);
 }
 
@@ -93,6 +99,10 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
 	if (!blkg)
 		return NULL;
 
+	if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) ||
+	    blkg_rwstat_init(&blkg->stat_ios, gfp_mask))
+		goto err_free;
+
 	blkg->q = q;
 	INIT_LIST_HEAD(&blkg->q_node);
 	blkg->blkcg = blkcg;
@@ -113,7 +123,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
 			continue;
 
 		/* alloc per-policy data and attach it to blkg */
-		pd = kzalloc_node(pol->pd_size, gfp_mask, q->node);
+		pd = pol->pd_alloc_fn(gfp_mask, q->node);
 		if (!pd)
 			goto err_free;
 
@@ -129,26 +139,11 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
 	return NULL;
 }
 
-/**
- * __blkg_lookup - internal version of blkg_lookup()
- * @blkcg: blkcg of interest
- * @q: request_queue of interest
- * @update_hint: whether to update lookup hint with the result or not
- *
- * This is internal version and shouldn't be used by policy
- * implementations.  Looks up blkgs for the @blkcg - @q pair regardless of
- * @q's bypass state.  If @update_hint is %true, the caller should be
- * holding @q->queue_lock and lookup hint is updated on success.
- */
-struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
-			       bool update_hint)
+struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
+				      struct request_queue *q, bool update_hint)
 {
 	struct blkcg_gq *blkg;
 
-	blkg = rcu_dereference(blkcg->blkg_hint);
-	if (blkg && blkg->q == q)
-		return blkg;
-
 	/*
 	 * Hint didn't match.  Look up from the radix tree.  Note that the
 	 * hint can only be updated under queue_lock as otherwise @blkg
@@ -166,29 +161,11 @@ struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
 
 	return NULL;
 }
-
-/**
- * blkg_lookup - lookup blkg for the specified blkcg - q pair
- * @blkcg: blkcg of interest
- * @q: request_queue of interest
- *
- * Lookup blkg for the @blkcg - @q pair.  This function should be called
- * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
- * - see blk_queue_bypass_start() for details.
- */
-struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q)
-{
-	WARN_ON_ONCE(!rcu_read_lock_held());
-
-	if (unlikely(blk_queue_bypass(q)))
-		return NULL;
-	return __blkg_lookup(blkcg, q, false);
-}
-EXPORT_SYMBOL_GPL(blkg_lookup);
+EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
 
 /*
  * If @new_blkg is %NULL, this function tries to allocate a new one as
- * necessary using %GFP_ATOMIC.  @new_blkg is always consumed on return.
+ * necessary using %GFP_NOWAIT.  @new_blkg is always consumed on return.
  */
 static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
 				    struct request_queue *q,
@@ -203,12 +180,12 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
 
 	/* blkg holds a reference to blkcg */
 	if (!css_tryget_online(&blkcg->css)) {
-		ret = -EINVAL;
+		ret = -ENODEV;
 		goto err_free_blkg;
 	}
 
 	wb_congested = wb_congested_get_create(&q->backing_dev_info,
-					       blkcg->css.id, GFP_ATOMIC);
+					       blkcg->css.id, GFP_NOWAIT);
 	if (!wb_congested) {
 		ret = -ENOMEM;
 		goto err_put_css;
@@ -216,7 +193,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
 
 	/* allocate */
 	if (!new_blkg) {
-		new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);
+		new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT);
 		if (unlikely(!new_blkg)) {
 			ret = -ENOMEM;
 			goto err_put_congested;
@@ -229,7 +206,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
 	if (blkcg_parent(blkcg)) {
 		blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
 		if (WARN_ON_ONCE(!blkg->parent)) {
-			ret = -EINVAL;
+			ret = -ENODEV;
 			goto err_put_congested;
 		}
 		blkg_get(blkg->parent);
@@ -240,7 +217,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
 		struct blkcg_policy *pol = blkcg_policy[i];
 
 		if (blkg->pd[i] && pol->pd_init_fn)
-			pol->pd_init_fn(blkg);
+			pol->pd_init_fn(blkg->pd[i]);
 	}
 
 	/* insert */
@@ -254,7 +231,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
 			struct blkcg_policy *pol = blkcg_policy[i];
 
 			if (blkg->pd[i] && pol->pd_online_fn)
-				pol->pd_online_fn(blkg);
+				pol->pd_online_fn(blkg->pd[i]);
 		}
 	}
 	blkg->online = true;
@@ -303,7 +280,7 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 	 * we shouldn't allow anything to go through for a bypassing queue.
 	 */
 	if (unlikely(blk_queue_bypass(q)))
-		return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY);
+		return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
 
 	blkg = __blkg_lookup(blkcg, q, true);
 	if (blkg)
@@ -327,11 +304,11 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 			return blkg;
 	}
 }
-EXPORT_SYMBOL_GPL(blkg_lookup_create);
 
 static void blkg_destroy(struct blkcg_gq *blkg)
 {
 	struct blkcg *blkcg = blkg->blkcg;
+	struct blkcg_gq *parent = blkg->parent;
 	int i;
 
 	lockdep_assert_held(blkg->q->queue_lock);
@@ -345,8 +322,14 @@ static void blkg_destroy(struct blkcg_gq *blkg)
 		struct blkcg_policy *pol = blkcg_policy[i];
 
 		if (blkg->pd[i] && pol->pd_offline_fn)
-			pol->pd_offline_fn(blkg);
+			pol->pd_offline_fn(blkg->pd[i]);
+	}
+
+	if (parent) {
+		blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);
+		blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
 	}
+
 	blkg->online = false;
 
 	radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
@@ -400,15 +383,6 @@ static void blkg_destroy_all(struct request_queue *q)
 void __blkg_release_rcu(struct rcu_head *rcu_head)
 {
 	struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head);
-	int i;
-
-	/* tell policies that this one is being freed */
-	for (i = 0; i < BLKCG_MAX_POLS; i++) {
-		struct blkcg_policy *pol = blkcg_policy[i];
-
-		if (blkg->pd[i] && pol->pd_exit_fn)
-			pol->pd_exit_fn(blkg);
-	}
 
 	/* release the blkcg and parent blkg refs this blkg has been holding */
 	css_put(&blkg->blkcg->css);
@@ -472,12 +446,14 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css,
 	 * anyway.  If you get hit by a race, retry.
 	 */
 	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
+		blkg_rwstat_reset(&blkg->stat_bytes);
+		blkg_rwstat_reset(&blkg->stat_ios);
+
 		for (i = 0; i < BLKCG_MAX_POLS; i++) {
 			struct blkcg_policy *pol = blkcg_policy[i];
 
-			if (blkcg_policy_enabled(blkg->q, pol) &&
-			    pol->pd_reset_stats_fn)
-				pol->pd_reset_stats_fn(blkg);
+			if (blkg->pd[i] && pol->pd_reset_stats_fn)
+				pol->pd_reset_stats_fn(blkg->pd[i]);
 		}
 	}
 
@@ -486,13 +462,14 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css,
 	return 0;
 }
 
-static const char *blkg_dev_name(struct blkcg_gq *blkg)
+const char *blkg_dev_name(struct blkcg_gq *blkg)
 {
 	/* some drivers (floppy) instantiate a queue w/o disk registered */
 	if (blkg->q->backing_dev_info.dev)
 		return dev_name(blkg->q->backing_dev_info.dev);
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(blkg_dev_name);
 
 /**
  * blkcg_print_blkgs - helper for printing per-blkg data
@@ -581,9 +558,10 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 
 	for (i = 0; i < BLKG_RWSTAT_NR; i++)
 		seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
-			   (unsigned long long)rwstat->cnt[i]);
+			   (unsigned long long)atomic64_read(&rwstat->aux_cnt[i]));
 
-	v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE];
+	v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) +
+		atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]);
 	seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
 	return v;
 }
@@ -620,31 +598,122 @@ u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 }
 EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
 
+static u64 blkg_prfill_rwstat_field(struct seq_file *sf,
+				    struct blkg_policy_data *pd, int off)
+{
+	struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->blkg + off);
+
+	return __blkg_prfill_rwstat(sf, pd, &rwstat);
+}
+
+/**
+ * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes
+ * @sf: seq_file to print to
+ * @v: unused
+ *
+ * To be used as cftype->seq_show to print blkg->stat_bytes.
+ * cftype->private must be set to the blkcg_policy.
+ */
+int blkg_print_stat_bytes(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+			  blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
+			  offsetof(struct blkcg_gq, stat_bytes), true);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(blkg_print_stat_bytes);
+
+/**
+ * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios
+ * @sf: seq_file to print to
+ * @v: unused
+ *
+ * To be used as cftype->seq_show to print blkg->stat_ios.  cftype->private
+ * must be set to the blkcg_policy.
+ */
+int blkg_print_stat_ios(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+			  blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
+			  offsetof(struct blkcg_gq, stat_ios), true);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(blkg_print_stat_ios);
+
+static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf,
+					      struct blkg_policy_data *pd,
+					      int off)
+{
+	struct blkg_rwstat rwstat = blkg_rwstat_recursive_sum(pd->blkg,
+							      NULL, off);
+	return __blkg_prfill_rwstat(sf, pd, &rwstat);
+}
+
+/**
+ * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes
+ * @sf: seq_file to print to
+ * @v: unused
+ */
+int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+			  blkg_prfill_rwstat_field_recursive,
+			  (void *)seq_cft(sf)->private,
+			  offsetof(struct blkcg_gq, stat_bytes), true);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive);
+
+/**
+ * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios
+ * @sf: seq_file to print to
+ * @v: unused
+ */
+int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+			  blkg_prfill_rwstat_field_recursive,
+			  (void *)seq_cft(sf)->private,
+			  offsetof(struct blkcg_gq, stat_ios), true);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive);
+
 /**
  * blkg_stat_recursive_sum - collect hierarchical blkg_stat
- * @pd: policy private data of interest
- * @off: offset to the blkg_stat in @pd
+ * @blkg: blkg of interest
+ * @pol: blkcg_policy which contains the blkg_stat
+ * @off: offset to the blkg_stat in blkg_policy_data or @blkg
+ *
+ * Collect the blkg_stat specified by @blkg, @pol and @off and all its
+ * online descendants and their aux counts.  The caller must be holding the
+ * queue lock for online tests.
  *
- * Collect the blkg_stat specified by @off from @pd and all its online
- * descendants and return the sum.  The caller must be holding the queue
- * lock for online tests.
+ * If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is
+ * at @off bytes into @blkg's blkg_policy_data of the policy.
  */
-u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off)
+u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
+			    struct blkcg_policy *pol, int off)
 {
-	struct blkcg_policy *pol = blkcg_policy[pd->plid];
 	struct blkcg_gq *pos_blkg;
 	struct cgroup_subsys_state *pos_css;
 	u64 sum = 0;
 
-	lockdep_assert_held(pd->blkg->q->queue_lock);
+	lockdep_assert_held(blkg->q->queue_lock);
 
 	rcu_read_lock();
-	blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
-		struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
-		struct blkg_stat *stat = (void *)pos_pd + off;
+	blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
+		struct blkg_stat *stat;
+
+		if (!pos_blkg->online)
+			continue;
+
+		if (pol)
+			stat = (void *)blkg_to_pd(pos_blkg, pol) + off;
+		else
+			stat = (void *)blkg + off;
 
-		if (pos_blkg->online)
-			sum += blkg_stat_read(stat);
+		sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt);
 	}
 	rcu_read_unlock();
 
@@ -654,37 +723,43 @@ EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
 
 /**
  * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
- * @pd: policy private data of interest
- * @off: offset to the blkg_stat in @pd
+ * @blkg: blkg of interest
+ * @pol: blkcg_policy which contains the blkg_rwstat
+ * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
+ *
+ * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
+ * online descendants and their aux counts.  The caller must be holding the
+ * queue lock for online tests.
  *
- * Collect the blkg_rwstat specified by @off from @pd and all its online
- * descendants and return the sum.  The caller must be holding the queue
- * lock for online tests.
+ * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
+ * is at @off bytes into @blkg's blkg_policy_data of the policy.
  */
-struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
-					     int off)
+struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
+					     struct blkcg_policy *pol, int off)
 {
-	struct blkcg_policy *pol = blkcg_policy[pd->plid];
 	struct blkcg_gq *pos_blkg;
 	struct cgroup_subsys_state *pos_css;
 	struct blkg_rwstat sum = { };
 	int i;
 
-	lockdep_assert_held(pd->blkg->q->queue_lock);
+	lockdep_assert_held(blkg->q->queue_lock);
 
 	rcu_read_lock();
-	blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
-		struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
-		struct blkg_rwstat *rwstat = (void *)pos_pd + off;
-		struct blkg_rwstat tmp;
+	blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
+		struct blkg_rwstat *rwstat;
 
 		if (!pos_blkg->online)
 			continue;
 
-		tmp = blkg_rwstat_read(rwstat);
+		if (pol)
+			rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
+		else
+			rwstat = (void *)pos_blkg + off;
 
 		for (i = 0; i < BLKG_RWSTAT_NR; i++)
-			sum.cnt[i] += tmp.cnt[i];
+			atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) +
+				percpu_counter_sum_positive(&rwstat->cpu_cnt[i]),
+				&sum.aux_cnt[i]);
 	}
 	rcu_read_unlock();
 
@@ -700,29 +775,34 @@ EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
  * @ctx: blkg_conf_ctx to be filled
  *
  * Parse per-blkg config update from @input and initialize @ctx with the
- * result.  @ctx->blkg points to the blkg to be updated and @ctx->v the new
- * value.  This function returns with RCU read lock and queue lock held and
- * must be paired with blkg_conf_finish().
+ * result.  @ctx->blkg points to the blkg to be updated and @ctx->body the
+ * part of @input following MAJ:MIN.  This function returns with RCU read
+ * lock and queue lock held and must be paired with blkg_conf_finish().
  */
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
-		   const char *input, struct blkg_conf_ctx *ctx)
+		   char *input, struct blkg_conf_ctx *ctx)
 	__acquires(rcu) __acquires(disk->queue->queue_lock)
 {
 	struct gendisk *disk;
 	struct blkcg_gq *blkg;
 	unsigned int major, minor;
-	unsigned long long v;
-	int part, ret;
+	int key_len, part, ret;
+	char *body;
 
-	if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
+	if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
 		return -EINVAL;
 
+	body = input + key_len;
+	if (!isspace(*body))
+		return -EINVAL;
+	body = skip_spaces(body);
+
 	disk = get_gendisk(MKDEV(major, minor), &part);
 	if (!disk)
-		return -EINVAL;
+		return -ENODEV;
 	if (part) {
 		put_disk(disk);
-		return -EINVAL;
+		return -ENODEV;
 	}
 
 	rcu_read_lock();
@@ -731,7 +811,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 	if (blkcg_policy_enabled(disk->queue, pol))
 		blkg = blkg_lookup_create(blkcg, disk->queue);
 	else
-		blkg = ERR_PTR(-EINVAL);
+		blkg = ERR_PTR(-EOPNOTSUPP);
 
 	if (IS_ERR(blkg)) {
 		ret = PTR_ERR(blkg);
@@ -753,7 +833,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 
 	ctx->disk = disk;
 	ctx->blkg = blkg;
-	ctx->v = v;
+	ctx->body = body;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(blkg_conf_prep);
@@ -774,7 +854,54 @@ void blkg_conf_finish(struct blkg_conf_ctx *ctx)
 }
 EXPORT_SYMBOL_GPL(blkg_conf_finish);
 
+static int blkcg_print_stat(struct seq_file *sf, void *v)
+{
+	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
+	struct blkcg_gq *blkg;
+
+	rcu_read_lock();
+
+	hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
+		const char *dname;
+		struct blkg_rwstat rwstat;
+		u64 rbytes, wbytes, rios, wios;
+
+		dname = blkg_dev_name(blkg);
+		if (!dname)
+			continue;
+
+		spin_lock_irq(blkg->q->queue_lock);
+
+		rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
+					offsetof(struct blkcg_gq, stat_bytes));
+		rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
+		wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
+
+		rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
+					offsetof(struct blkcg_gq, stat_ios));
+		rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
+		wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
+
+		spin_unlock_irq(blkg->q->queue_lock);
+
+		if (rbytes || wbytes || rios || wios)
+			seq_printf(sf, "%s rbytes=%llu wbytes=%llu rios=%llu wios=%llu\n",
+				   dname, rbytes, wbytes, rios, wios);
+	}
+
+	rcu_read_unlock();
+	return 0;
+}
+
 struct cftype blkcg_files[] = {
+	{
+		.name = "stat",
+		.seq_show = blkcg_print_stat,
+	},
+	{ }	/* terminate */
+};
+
+struct cftype blkcg_legacy_files[] = {
 	{
 		.name = "reset_stats",
 		.write_u64 = blkcg_reset_stats,
@@ -822,18 +949,19 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css)
 static void blkcg_css_free(struct cgroup_subsys_state *css)
 {
 	struct blkcg *blkcg = css_to_blkcg(css);
+	int i;
 
 	mutex_lock(&blkcg_pol_mutex);
+
 	list_del(&blkcg->all_blkcgs_node);
-	mutex_unlock(&blkcg_pol_mutex);
 
-	if (blkcg != &blkcg_root) {
-		int i;
+	for (i = 0; i < BLKCG_MAX_POLS; i++)
+		if (blkcg->cpd[i])
+			blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
 
-		for (i = 0; i < BLKCG_MAX_POLS; i++)
-			kfree(blkcg->pd[i]);
-		kfree(blkcg);
-	}
+	mutex_unlock(&blkcg_pol_mutex);
+
+	kfree(blkcg);
 }
 
 static struct cgroup_subsys_state *
@@ -847,13 +975,12 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
 
 	if (!parent_css) {
 		blkcg = &blkcg_root;
-		goto done;
-	}
-
-	blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
-	if (!blkcg) {
-		ret = ERR_PTR(-ENOMEM);
-		goto free_blkcg;
+	} else {
+		blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
+		if (!blkcg) {
+			ret = ERR_PTR(-ENOMEM);
+			goto free_blkcg;
+		}
 	}
 
 	for (i = 0; i < BLKCG_MAX_POLS ; i++) {
@@ -866,23 +993,23 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
 		 * check if the policy requires any specific per-cgroup
 		 * data: if it does, allocate and initialize it.
 		 */
-		if (!pol || !pol->cpd_size)
+		if (!pol || !pol->cpd_alloc_fn)
 			continue;
 
-		BUG_ON(blkcg->pd[i]);
-		cpd = kzalloc(pol->cpd_size, GFP_KERNEL);
+		cpd = pol->cpd_alloc_fn(GFP_KERNEL);
 		if (!cpd) {
 			ret = ERR_PTR(-ENOMEM);
 			goto free_pd_blkcg;
 		}
-		blkcg->pd[i] = cpd;
+		blkcg->cpd[i] = cpd;
+		cpd->blkcg = blkcg;
 		cpd->plid = i;
-		pol->cpd_init_fn(blkcg);
+		if (pol->cpd_init_fn)
+			pol->cpd_init_fn(cpd);
 	}
 
-done:
 	spin_lock_init(&blkcg->lock);
-	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC);
+	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT);
 	INIT_HLIST_HEAD(&blkcg->blkg_list);
 #ifdef CONFIG_CGROUP_WRITEBACK
 	INIT_LIST_HEAD(&blkcg->cgwb_list);
@@ -894,7 +1021,8 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
 
 free_pd_blkcg:
 	for (i--; i >= 0; i--)
-		kfree(blkcg->pd[i]);
+		if (blkcg->cpd[i])
+			blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
 free_blkcg:
 	kfree(blkcg);
 	mutex_unlock(&blkcg_pol_mutex);
@@ -938,7 +1066,7 @@ int blkcg_init_queue(struct request_queue *q)
 		radix_tree_preload_end();
 
 	if (IS_ERR(blkg)) {
-		kfree(new_blkg);
+		blkg_free(new_blkg);
 		return PTR_ERR(blkg);
 	}
 
@@ -1015,12 +1143,35 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css,
 	return ret;
 }
 
-struct cgroup_subsys blkio_cgrp_subsys = {
+static void blkcg_bind(struct cgroup_subsys_state *root_css)
+{
+	int i;
+
+	mutex_lock(&blkcg_pol_mutex);
+
+	for (i = 0; i < BLKCG_MAX_POLS; i++) {
+		struct blkcg_policy *pol = blkcg_policy[i];
+		struct blkcg *blkcg;
+
+		if (!pol || !pol->cpd_bind_fn)
+			continue;
+
+		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node)
+			if (blkcg->cpd[pol->plid])
+				pol->cpd_bind_fn(blkcg->cpd[pol->plid]);
+	}
+	mutex_unlock(&blkcg_pol_mutex);
+}
+
+struct cgroup_subsys io_cgrp_subsys = {
 	.css_alloc = blkcg_css_alloc,
 	.css_offline = blkcg_css_offline,
 	.css_free = blkcg_css_free,
 	.can_attach = blkcg_can_attach,
-	.legacy_cftypes = blkcg_files,
+	.bind = blkcg_bind,
+	.dfl_cftypes = blkcg_files,
+	.legacy_cftypes = blkcg_legacy_files,
+	.legacy_name = "blkio",
 #ifdef CONFIG_MEMCG
 	/*
 	 * This ensures that, if available, memcg is automatically enabled
@@ -1030,7 +1181,7 @@ struct cgroup_subsys blkio_cgrp_subsys = {
 	.depends_on = 1 << memory_cgrp_id,
 #endif
 };
-EXPORT_SYMBOL_GPL(blkio_cgrp_subsys);
+EXPORT_SYMBOL_GPL(io_cgrp_subsys);
 
 /**
  * blkcg_activate_policy - activate a blkcg policy on a request_queue
@@ -1051,65 +1202,54 @@ EXPORT_SYMBOL_GPL(blkio_cgrp_subsys);
 int blkcg_activate_policy(struct request_queue *q,
 			  const struct blkcg_policy *pol)
 {
-	LIST_HEAD(pds);
+	struct blkg_policy_data *pd_prealloc = NULL;
 	struct blkcg_gq *blkg;
-	struct blkg_policy_data *pd, *nd;
-	int cnt = 0, ret;
+	int ret;
 
 	if (blkcg_policy_enabled(q, pol))
 		return 0;
 
-	/* count and allocate policy_data for all existing blkgs */
 	blk_queue_bypass_start(q);
-	spin_lock_irq(q->queue_lock);
-	list_for_each_entry(blkg, &q->blkg_list, q_node)
-		cnt++;
-	spin_unlock_irq(q->queue_lock);
-
-	/* allocate per-blkg policy data for all existing blkgs */
-	while (cnt--) {
-		pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node);
-		if (!pd) {
+pd_prealloc:
+	if (!pd_prealloc) {
+		pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node);
+		if (!pd_prealloc) {
 			ret = -ENOMEM;
-			goto out_free;
+			goto out_bypass_end;
 		}
-		list_add_tail(&pd->alloc_node, &pds);
 	}
 
-	/*
-	 * Install the allocated pds and cpds. With @q bypassing, no new blkg
-	 * should have been created while the queue lock was dropped.
-	 */
 	spin_lock_irq(q->queue_lock);
 
 	list_for_each_entry(blkg, &q->blkg_list, q_node) {
-		if (WARN_ON(list_empty(&pds))) {
-			/* umm... this shouldn't happen, just abort */
-			ret = -ENOMEM;
-			goto out_unlock;
-		}
-		pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node);
-		list_del_init(&pd->alloc_node);
+		struct blkg_policy_data *pd;
 
-		/* grab blkcg lock too while installing @pd on @blkg */
-		spin_lock(&blkg->blkcg->lock);
+		if (blkg->pd[pol->plid])
+			continue;
+
+		pd = pol->pd_alloc_fn(GFP_NOWAIT, q->node);
+		if (!pd)
+			swap(pd, pd_prealloc);
+		if (!pd) {
+			spin_unlock_irq(q->queue_lock);
+			goto pd_prealloc;
+		}
 
 		blkg->pd[pol->plid] = pd;
 		pd->blkg = blkg;
 		pd->plid = pol->plid;
-		pol->pd_init_fn(blkg);
-
-		spin_unlock(&blkg->blkcg->lock);
+		if (pol->pd_init_fn)
+			pol->pd_init_fn(pd);
 	}
 
 	__set_bit(pol->plid, q->blkcg_pols);
 	ret = 0;
-out_unlock:
+
 	spin_unlock_irq(q->queue_lock);
-out_free:
+out_bypass_end:
 	blk_queue_bypass_end(q);
-	list_for_each_entry_safe(pd, nd, &pds, alloc_node)
-		kfree(pd);
+	if (pd_prealloc)
+		pol->pd_free_fn(pd_prealloc);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(blkcg_activate_policy);
@@ -1139,13 +1279,12 @@ void blkcg_deactivate_policy(struct request_queue *q,
 		/* grab blkcg lock too while removing @pd from @blkg */
 		spin_lock(&blkg->blkcg->lock);
 
-		if (pol->pd_offline_fn)
-			pol->pd_offline_fn(blkg);
-		if (pol->pd_exit_fn)
-			pol->pd_exit_fn(blkg);
-
-		kfree(blkg->pd[pol->plid]);
-		blkg->pd[pol->plid] = NULL;
+		if (blkg->pd[pol->plid]) {
+			if (pol->pd_offline_fn)
+				pol->pd_offline_fn(blkg->pd[pol->plid]);
+			pol->pd_free_fn(blkg->pd[pol->plid]);
+			blkg->pd[pol->plid] = NULL;
+		}
 
 		spin_unlock(&blkg->blkcg->lock);
 	}
@@ -1167,9 +1306,6 @@ int blkcg_policy_register(struct blkcg_policy *pol)
 	struct blkcg *blkcg;
 	int i, ret;
 
-	if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data)))
-		return -EINVAL;
-
 	mutex_lock(&blkcg_pol_register_mutex);
 	mutex_lock(&blkcg_pol_mutex);
 
@@ -1186,36 +1322,42 @@ int blkcg_policy_register(struct blkcg_policy *pol)
 	blkcg_policy[pol->plid] = pol;
 
 	/* allocate and install cpd's */
-	if (pol->cpd_size) {
+	if (pol->cpd_alloc_fn) {
 		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
 			struct blkcg_policy_data *cpd;
 
-			cpd = kzalloc(pol->cpd_size, GFP_KERNEL);
+			cpd = pol->cpd_alloc_fn(GFP_KERNEL);
 			if (!cpd) {
 				mutex_unlock(&blkcg_pol_mutex);
 				goto err_free_cpds;
 			}
 
-			blkcg->pd[pol->plid] = cpd;
+			blkcg->cpd[pol->plid] = cpd;
+			cpd->blkcg = blkcg;
 			cpd->plid = pol->plid;
-			pol->cpd_init_fn(blkcg);
+			pol->cpd_init_fn(cpd);
 		}
 	}
 
 	mutex_unlock(&blkcg_pol_mutex);
 
 	/* everything is in place, add intf files for the new policy */
-	if (pol->cftypes)
-		WARN_ON(cgroup_add_legacy_cftypes(&blkio_cgrp_subsys,
-						  pol->cftypes));
+	if (pol->dfl_cftypes)
+		WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys,
+					       pol->dfl_cftypes));
+	if (pol->legacy_cftypes)
+		WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys,
+						  pol->legacy_cftypes));
 	mutex_unlock(&blkcg_pol_register_mutex);
 	return 0;
 
 err_free_cpds:
-	if (pol->cpd_size) {
+	if (pol->cpd_alloc_fn) {
 		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
-			kfree(blkcg->pd[pol->plid]);
-			blkcg->pd[pol->plid] = NULL;
+			if (blkcg->cpd[pol->plid]) {
+				pol->cpd_free_fn(blkcg->cpd[pol->plid]);
+				blkcg->cpd[pol->plid] = NULL;
+			}
 		}
 	}
 	blkcg_policy[pol->plid] = NULL;
@@ -1242,16 +1384,20 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
 		goto out_unlock;
 
 	/* kill the intf files first */
-	if (pol->cftypes)
-		cgroup_rm_cftypes(pol->cftypes);
+	if (pol->dfl_cftypes)
+		cgroup_rm_cftypes(pol->dfl_cftypes);
+	if (pol->legacy_cftypes)
+		cgroup_rm_cftypes(pol->legacy_cftypes);
 
 	/* remove cpds and unregister */
 	mutex_lock(&blkcg_pol_mutex);
 
-	if (pol->cpd_size) {
+	if (pol->cpd_alloc_fn) {
 		list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
-			kfree(blkcg->pd[pol->plid]);
-			blkcg->pd[pol->plid] = NULL;
+			if (blkcg->cpd[pol->plid]) {
+				pol->cpd_free_fn(blkcg->cpd[pol->plid]);
+				blkcg->cpd[pol->plid] = NULL;
+			}
 		}
 	}
 	blkcg_policy[pol->plid] = NULL;

block/blk-core.c

@@ -1888,8 +1888,8 @@ generic_make_request_checks(struct bio *bio)
 	 */
 	create_io_context(GFP_ATOMIC, q->node);
 
-	if (blk_throtl_bio(q, bio))
-		return false;	/* throttled, will be resubmitted later */
+	if (!blkcg_bio_issue_check(q, bio))
+		return false;
 
 	trace_block_bio_queue(q, bio);
 	return true;

block/blk-throttle.c

@@ -83,14 +83,6 @@ enum tg_state_flags {
 
 #define rb_entry_tg(node)	rb_entry((node), struct throtl_grp, rb_node)
 
-/* Per-cpu group stats */
-struct tg_stats_cpu {
-	/* total bytes transferred */
-	struct blkg_rwstat		service_bytes;
-	/* total IOs serviced, post merge */
-	struct blkg_rwstat		serviced;
-};
-
 struct throtl_grp {
 	/* must be the first member */
 	struct blkg_policy_data pd;
@@ -141,12 +133,6 @@ struct throtl_grp {
 	/* When did we start a new slice */
 	unsigned long slice_start[2];
 	unsigned long slice_end[2];
-
-	/* Per cpu stats pointer */
-	struct tg_stats_cpu __percpu *stats_cpu;
-
-	/* List of tgs waiting for per cpu stats memory to be allocated */
-	struct list_head stats_alloc_node;
 };
 
 struct throtl_data
@@ -168,13 +154,6 @@ struct throtl_data
 	struct work_struct dispatch_work;
 };
 
-/* list and work item to allocate percpu group stats */
-static DEFINE_SPINLOCK(tg_stats_alloc_lock);
-static LIST_HEAD(tg_stats_alloc_list);
-
-static void tg_stats_alloc_fn(struct work_struct *);
-static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn);
-
 static void throtl_pending_timer_fn(unsigned long arg);
 
 static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
@@ -192,11 +171,6 @@ static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
 	return pd_to_blkg(&tg->pd);
 }
 
-static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
-{
-	return blkg_to_tg(td->queue->root_blkg);
-}
-
 /**
  * sq_to_tg - return the throl_grp the specified service queue belongs to
  * @sq: the throtl_service_queue of interest
@@ -256,53 +230,6 @@ static struct throtl_data *sq_to_td(struct throtl_service_queue *sq)
 	}								\
 } while (0)
 
-static void tg_stats_init(struct tg_stats_cpu *tg_stats)
-{
-	blkg_rwstat_init(&tg_stats->service_bytes);
-	blkg_rwstat_init(&tg_stats->serviced);
-}
-
-/*
- * Worker for allocating per cpu stat for tgs. This is scheduled on the
- * system_wq once there are some groups on the alloc_list waiting for
- * allocation.
- */
-static void tg_stats_alloc_fn(struct work_struct *work)
-{
-	static struct tg_stats_cpu *stats_cpu;	/* this fn is non-reentrant */
-	struct delayed_work *dwork = to_delayed_work(work);
-	bool empty = false;
-
-alloc_stats:
-	if (!stats_cpu) {
-		int cpu;
-
-		stats_cpu = alloc_percpu(struct tg_stats_cpu);
-		if (!stats_cpu) {
-			/* allocation failed, try again after some time */
-			schedule_delayed_work(dwork, msecs_to_jiffies(10));
-			return;
-		}
-		for_each_possible_cpu(cpu)
-			tg_stats_init(per_cpu_ptr(stats_cpu, cpu));
-	}
-
-	spin_lock_irq(&tg_stats_alloc_lock);
-
-	if (!list_empty(&tg_stats_alloc_list)) {
-		struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
-							 struct throtl_grp,
-							 stats_alloc_node);
-		swap(tg->stats_cpu, stats_cpu);
-		list_del_init(&tg->stats_alloc_node);
-	}
-
-	empty = list_empty(&tg_stats_alloc_list);
-	spin_unlock_irq(&tg_stats_alloc_lock);
-	if (!empty)
-		goto alloc_stats;
-}
-
 static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg)
 {
 	INIT_LIST_HEAD(&qn->node);
@@ -387,29 +314,46 @@ static struct bio *throtl_pop_queued(struct list_head *queued,
 }
 
 /* init a service_queue, assumes the caller zeroed it */
-static void throtl_service_queue_init(struct throtl_service_queue *sq,
-				      struct throtl_service_queue *parent_sq)
+static void throtl_service_queue_init(struct throtl_service_queue *sq)
 {
 	INIT_LIST_HEAD(&sq->queued[0]);
 	INIT_LIST_HEAD(&sq->queued[1]);
 	sq->pending_tree = RB_ROOT;
-	sq->parent_sq = parent_sq;
 	setup_timer(&sq->pending_timer, throtl_pending_timer_fn,
 		    (unsigned long)sq);
 }
 
-static void throtl_service_queue_exit(struct throtl_service_queue *sq)
+static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node)
 {
-	del_timer_sync(&sq->pending_timer);
+	struct throtl_grp *tg;
+	int rw;
+
+	tg = kzalloc_node(sizeof(*tg), gfp, node);
+	if (!tg)
+		return NULL;
+
+	throtl_service_queue_init(&tg->service_queue);
+
+	for (rw = READ; rw <= WRITE; rw++) {
+		throtl_qnode_init(&tg->qnode_on_self[rw], tg);
+		throtl_qnode_init(&tg->qnode_on_parent[rw], tg);
+	}
+
+	RB_CLEAR_NODE(&tg->rb_node);
+	tg->bps[READ] = -1;
+	tg->bps[WRITE] = -1;
+	tg->iops[READ] = -1;
+	tg->iops[WRITE] = -1;
+
+	return &tg->pd;
 }
 
-static void throtl_pd_init(struct blkcg_gq *blkg)
+static void throtl_pd_init(struct blkg_policy_data *pd)
 {
-	struct throtl_grp *tg = blkg_to_tg(blkg);
+	struct throtl_grp *tg = pd_to_tg(pd);
+	struct blkcg_gq *blkg = tg_to_blkg(tg);
 	struct throtl_data *td = blkg->q->td;
-	struct throtl_service_queue *parent_sq;
-	unsigned long flags;
-	int rw;
+	struct throtl_service_queue *sq = &tg->service_queue;
 
 	/*
 	 * If on the default hierarchy, we switch to properly hierarchical
@@ -424,35 +368,10 @@ static void throtl_pd_init(struct blkcg_gq *blkg)
 	 * Limits of a group don't interact with limits of other groups
 	 * regardless of the position of the group in the hierarchy.
 	 */
-	parent_sq = &td->service_queue;
-
+	sq->parent_sq = &td->service_queue;
 	if (cgroup_on_dfl(blkg->blkcg->css.cgroup) && blkg->parent)
-		parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
-
-	throtl_service_queue_init(&tg->service_queue, parent_sq);
-
-	for (rw = READ; rw <= WRITE; rw++) {
-		throtl_qnode_init(&tg->qnode_on_self[rw], tg);
-		throtl_qnode_init(&tg->qnode_on_parent[rw], tg);
-	}
-
-	RB_CLEAR_NODE(&tg->rb_node);
+		sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
 	tg->td = td;
-
-	tg->bps[READ] = -1;
-	tg->bps[WRITE] = -1;
-	tg->iops[READ] = -1;
-	tg->iops[WRITE] = -1;
-
-	/*
-	 * Ugh... We need to perform per-cpu allocation for tg->stats_cpu
-	 * but percpu allocator can't be called from IO path.  Queue tg on
-	 * tg_stats_alloc_list and allocate from work item.
-	 */
-	spin_lock_irqsave(&tg_stats_alloc_lock, flags);
-	list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
-	schedule_delayed_work(&tg_stats_alloc_work, 0);
-	spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
 }
 
 /*
@@ -470,83 +389,21 @@ static void tg_update_has_rules(struct throtl_grp *tg)
 				    (tg->bps[rw] != -1 || tg->iops[rw] != -1);
 }
 
-static void throtl_pd_online(struct blkcg_gq *blkg)
+static void throtl_pd_online(struct blkg_policy_data *pd)
 {
 	/*
 	 * We don't want new groups to escape the limits of its ancestors.
 	 * Update has_rules[] after a new group is brought online.
 	 */
-	tg_update_has_rules(blkg_to_tg(blkg));
-}
-
-static void throtl_pd_exit(struct blkcg_gq *blkg)
-{
-	struct throtl_grp *tg = blkg_to_tg(blkg);
-	unsigned long flags;
-
-	spin_lock_irqsave(&tg_stats_alloc_lock, flags);
-	list_del_init(&tg->stats_alloc_node);
-	spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
-
-	free_percpu(tg->stats_cpu);
-
-	throtl_service_queue_exit(&tg->service_queue);
-}
-
-static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
-{
-	struct throtl_grp *tg = blkg_to_tg(blkg);
-	int cpu;
-
-	if (tg->stats_cpu == NULL)
-		return;
-
-	for_each_possible_cpu(cpu) {
-		struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
-
-		blkg_rwstat_reset(&sc->service_bytes);
-		blkg_rwstat_reset(&sc->serviced);
-	}
-}
-
-static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
-					   struct blkcg *blkcg)
-{
-	/*
-	 * This is the common case when there are no blkcgs.  Avoid lookup
-	 * in this case
-	 */
-	if (blkcg == &blkcg_root)
-		return td_root_tg(td);
-
-	return blkg_to_tg(blkg_lookup(blkcg, td->queue));
+	tg_update_has_rules(pd_to_tg(pd));
 }
 
-static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
-						  struct blkcg *blkcg)
+static void throtl_pd_free(struct blkg_policy_data *pd)
 {
-	struct request_queue *q = td->queue;
-	struct throtl_grp *tg = NULL;
-
-	/*
-	 * This is the common case when there are no blkcgs.  Avoid lookup
-	 * in this case
-	 */
-	if (blkcg == &blkcg_root) {
-		tg = td_root_tg(td);
-	} else {
-		struct blkcg_gq *blkg;
-
-		blkg = blkg_lookup_create(blkcg, q);
-
-		/* if %NULL and @q is alive, fall back to root_tg */
-		if (!IS_ERR(blkg))
-			tg = blkg_to_tg(blkg);
-		else if (!blk_queue_dying(q))
-			tg = td_root_tg(td);
-	}
+	struct throtl_grp *tg = pd_to_tg(pd);
 
-	return tg;
+	del_timer_sync(&tg->service_queue.pending_timer);
+	kfree(tg);
 }
 
 static struct throtl_grp *
@@ -956,32 +813,6 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
 	return 0;
 }
 
-static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes,
-					 int rw)
-{
-	struct throtl_grp *tg = blkg_to_tg(blkg);
-	struct tg_stats_cpu *stats_cpu;
-	unsigned long flags;
-
-	/* If per cpu stats are not allocated yet, don't do any accounting. */
-	if (tg->stats_cpu == NULL)
-		return;
-
-	/*
-	 * Disabling interrupts to provide mutual exclusion between two
-	 * writes on same cpu. It probably is not needed for 64bit. Not
-	 * optimizing that case yet.
-	 */
-	local_irq_save(flags);
-
-	stats_cpu = this_cpu_ptr(tg->stats_cpu);
-
-	blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
-	blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
-
-	local_irq_restore(flags);
-}
-
 static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
 {
 	bool rw = bio_data_dir(bio);
@@ -995,17 +826,9 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
 	 * more than once as a throttled bio will go through blk-throtl the
 	 * second time when it eventually gets issued.  Set it when a bio
 	 * is being charged to a tg.
-	 *
-	 * Dispatch stats aren't recursive and each @bio should only be
-	 * accounted by the @tg it was originally associated with.  Let's
-	 * update the stats when setting REQ_THROTTLED for the first time
-	 * which is guaranteed to be for the @bio's original tg.
 	 */
-	if (!(bio->bi_rw & REQ_THROTTLED)) {
+	if (!(bio->bi_rw & REQ_THROTTLED))
 		bio->bi_rw |= REQ_THROTTLED;
-		throtl_update_dispatch_stats(tg_to_blkg(tg),
-					     bio->bi_iter.bi_size, bio->bi_rw);
-	}
 }
 
 /**
@@ -1285,34 +1108,6 @@ static void blk_throtl_dispatch_work_fn(struct work_struct *work)
 	}
 }
 
-static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
-				struct blkg_policy_data *pd, int off)
-{
-	struct throtl_grp *tg = pd_to_tg(pd);
-	struct blkg_rwstat rwstat = { }, tmp;
-	int i, cpu;
-
-	if (tg->stats_cpu == NULL)
-		return 0;
-
-	for_each_possible_cpu(cpu) {
-		struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
-
-		tmp = blkg_rwstat_read((void *)sc + off);
-		for (i = 0; i < BLKG_RWSTAT_NR; i++)
-			rwstat.cnt[i] += tmp.cnt[i];
-	}
-
-	return __blkg_prfill_rwstat(sf, pd, &rwstat);
-}
-
-static int tg_print_cpu_rwstat(struct seq_file *sf, void *v)
-{
-	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_cpu_rwstat,
-			  &blkcg_policy_throtl, seq_cft(sf)->private, true);
-	return 0;
-}
-
 static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
 			      int off)
 {
@@ -1349,31 +1144,11 @@ static int tg_print_conf_uint(struct seq_file *sf, void *v)
 	return 0;
 }
 
-static ssize_t tg_set_conf(struct kernfs_open_file *of,
-			   char *buf, size_t nbytes, loff_t off, bool is_u64)
+static void tg_conf_updated(struct throtl_grp *tg)
 {
-	struct blkcg *blkcg = css_to_blkcg(of_css(of));
-	struct blkg_conf_ctx ctx;
-	struct throtl_grp *tg;
-	struct throtl_service_queue *sq;
-	struct blkcg_gq *blkg;
+	struct throtl_service_queue *sq = &tg->service_queue;
 	struct cgroup_subsys_state *pos_css;
-	int ret;
-
-	ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
-	if (ret)
-		return ret;
-
-	tg = blkg_to_tg(ctx.blkg);
-	sq = &tg->service_queue;
-
-	if (!ctx.v)
-		ctx.v = -1;
-
-	if (is_u64)
-		*(u64 *)((void *)tg + of_cft(of)->private) = ctx.v;
-	else
-		*(unsigned int *)((void *)tg + of_cft(of)->private) = ctx.v;
+	struct blkcg_gq *blkg;
 
 	throtl_log(&tg->service_queue,
 		   "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
@@ -1387,7 +1162,7 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
 	 * restrictions in the whole hierarchy and allows them to bypass
 	 * blk-throttle.
 	 */
-	blkg_for_each_descendant_pre(blkg, pos_css, ctx.blkg)
+	blkg_for_each_descendant_pre(blkg, pos_css, tg_to_blkg(tg))
 		tg_update_has_rules(blkg_to_tg(blkg));
 
 	/*
@@ -1405,9 +1180,39 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
 		tg_update_disptime(tg);
 		throtl_schedule_next_dispatch(sq->parent_sq, true);
 	}
+}
+
+static ssize_t tg_set_conf(struct kernfs_open_file *of,
+			   char *buf, size_t nbytes, loff_t off, bool is_u64)
+{
+	struct blkcg *blkcg = css_to_blkcg(of_css(of));
+	struct blkg_conf_ctx ctx;
+	struct throtl_grp *tg;
+	int ret;
+	u64 v;
 
+	ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
+	if (ret)
+		return ret;
+
+	ret = -EINVAL;
+	if (sscanf(ctx.body, "%llu", &v) != 1)
+		goto out_finish;
+	if (!v)
+		v = -1;
+
+	tg = blkg_to_tg(ctx.blkg);
+
+	if (is_u64)
+		*(u64 *)((void *)tg + of_cft(of)->private) = v;
+	else
+		*(unsigned int *)((void *)tg + of_cft(of)->private) = v;
+
+	tg_conf_updated(tg);
+	ret = 0;
+out_finish:
 	blkg_conf_finish(&ctx);
-	return nbytes;
+	return ret ?: nbytes;
 }
 
 static ssize_t tg_set_conf_u64(struct kernfs_open_file *of,
@@ -1422,7 +1227,7 @@ static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
 	return tg_set_conf(of, buf, nbytes, off, false);
 }
 
-static struct cftype throtl_files[] = {
+static struct cftype throtl_legacy_files[] = {
 	{
 		.name = "throttle.read_bps_device",
 		.private = offsetof(struct throtl_grp, bps[READ]),
@@ -1449,13 +1254,124 @@ static struct cftype throtl_files[] = {
 	},
 	{
 		.name = "throttle.io_service_bytes",
-		.private = offsetof(struct tg_stats_cpu, service_bytes),
-		.seq_show = tg_print_cpu_rwstat,
+		.private = (unsigned long)&blkcg_policy_throtl,
+		.seq_show = blkg_print_stat_bytes,
 	},
 	{
 		.name = "throttle.io_serviced",
-		.private = offsetof(struct tg_stats_cpu, serviced),
-		.seq_show = tg_print_cpu_rwstat,
+		.private = (unsigned long)&blkcg_policy_throtl,
+		.seq_show = blkg_print_stat_ios,
+	},
+	{ }	/* terminate */
+};
+
+static u64 tg_prfill_max(struct seq_file *sf, struct blkg_policy_data *pd,
+			 int off)
+{
+	struct throtl_grp *tg = pd_to_tg(pd);
+	const char *dname = blkg_dev_name(pd->blkg);
+	char bufs[4][21] = { "max", "max", "max", "max" };
+
+	if (!dname)
+		return 0;
+	if (tg->bps[READ] == -1 && tg->bps[WRITE] == -1 &&
+	    tg->iops[READ] == -1 && tg->iops[WRITE] == -1)
+		return 0;
+
+	if (tg->bps[READ] != -1)
+		snprintf(bufs[0], sizeof(bufs[0]), "%llu", tg->bps[READ]);
+	if (tg->bps[WRITE] != -1)
+		snprintf(bufs[1], sizeof(bufs[1]), "%llu", tg->bps[WRITE]);
+	if (tg->iops[READ] != -1)
+		snprintf(bufs[2], sizeof(bufs[2]), "%u", tg->iops[READ]);
+	if (tg->iops[WRITE] != -1)
+		snprintf(bufs[3], sizeof(bufs[3]), "%u", tg->iops[WRITE]);
+
+	seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s\n",
+		   dname, bufs[0], bufs[1], bufs[2], bufs[3]);
+	return 0;
+}
+
+static int tg_print_max(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_max,
+			  &blkcg_policy_throtl, seq_cft(sf)->private, false);
+	return 0;
+}
+
+static ssize_t tg_set_max(struct kernfs_open_file *of,
+			  char *buf, size_t nbytes, loff_t off)
+{
+	struct blkcg *blkcg = css_to_blkcg(of_css(of));
+	struct blkg_conf_ctx ctx;
+	struct throtl_grp *tg;
+	u64 v[4];
+	int ret;
+
+	ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
+	if (ret)
+		return ret;
+
+	tg = blkg_to_tg(ctx.blkg);
+
+	v[0] = tg->bps[READ];
+	v[1] = tg->bps[WRITE];
+	v[2] = tg->iops[READ];
+	v[3] = tg->iops[WRITE];
+
+	while (true) {
+		char tok[27];	/* wiops=18446744073709551616 */
+		char *p;
+		u64 val = -1;
+		int len;
+
+		if (sscanf(ctx.body, "%26s%n", tok, &len) != 1)
+			break;
+		if (tok[0] == '\0')
+			break;
+		ctx.body += len;
+
+		ret = -EINVAL;
+		p = tok;
+		strsep(&p, "=");
+		if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max")))
+			goto out_finish;
+
+		ret = -ERANGE;
+		if (!val)
+			goto out_finish;
+
+		ret = -EINVAL;
+		if (!strcmp(tok, "rbps"))
+			v[0] = val;
+		else if (!strcmp(tok, "wbps"))
+			v[1] = val;
+		else if (!strcmp(tok, "riops"))
+			v[2] = min_t(u64, val, UINT_MAX);
+		else if (!strcmp(tok, "wiops"))
+			v[3] = min_t(u64, val, UINT_MAX);
+		else
+			goto out_finish;
+	}
+
+	tg->bps[READ] = v[0];
+	tg->bps[WRITE] = v[1];
+	tg->iops[READ] = v[2];
+	tg->iops[WRITE] = v[3];
+
+	tg_conf_updated(tg);
+	ret = 0;
+out_finish:
+	blkg_conf_finish(&ctx);
+	return ret ?: nbytes;
+}
+
+static struct cftype throtl_files[] = {
+	{
+		.name = "max",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = tg_print_max,
+		.write = tg_set_max,
 	},
 	{ }	/* terminate */
 };
@@ -1468,52 +1384,33 @@ static void throtl_shutdown_wq(struct request_queue *q)
 }
 
 static struct blkcg_policy blkcg_policy_throtl = {
-	.pd_size		= sizeof(struct throtl_grp),
-	.cftypes		= throtl_files,
+	.dfl_cftypes		= throtl_files,
+	.legacy_cftypes		= throtl_legacy_files,
 
+	.pd_alloc_fn		= throtl_pd_alloc,
 	.pd_init_fn		= throtl_pd_init,
 	.pd_online_fn		= throtl_pd_online,
-	.pd_exit_fn		= throtl_pd_exit,
-	.pd_reset_stats_fn	= throtl_pd_reset_stats,
+	.pd_free_fn		= throtl_pd_free,
 };
 
-bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
+bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
+		    struct bio *bio)
 {
-	struct throtl_data *td = q->td;
 	struct throtl_qnode *qn = NULL;
-	struct throtl_grp *tg;
+	struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg);
 	struct throtl_service_queue *sq;
 	bool rw = bio_data_dir(bio);
-	struct blkcg *blkcg;
 	bool throttled = false;
 
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
 	/* see throtl_charge_bio() */
-	if (bio->bi_rw & REQ_THROTTLED)
+	if ((bio->bi_rw & REQ_THROTTLED) || !tg->has_rules[rw])
 		goto out;
 
-	/*
-	 * A throtl_grp pointer retrieved under rcu can be used to access
-	 * basic fields like stats and io rates. If a group has no rules,
-	 * just update the dispatch stats in lockless manner and return.
-	 */
-	rcu_read_lock();
-	blkcg = bio_blkcg(bio);
-	tg = throtl_lookup_tg(td, blkcg);
-	if (tg) {
-		if (!tg->has_rules[rw]) {
-			throtl_update_dispatch_stats(tg_to_blkg(tg),
-					bio->bi_iter.bi_size, bio->bi_rw);
-			goto out_unlock_rcu;
-		}
-	}
-
-	/*
-	 * Either group has not been allocated yet or it is not an unlimited
-	 * IO group
-	 */
 	spin_lock_irq(q->queue_lock);
-	tg = throtl_lookup_create_tg(td, blkcg);
-	if (unlikely(!tg))
+
+	if (unlikely(blk_queue_bypass(q)))
 		goto out_unlock;
 
 	sq = &tg->service_queue;
@@ -1580,8 +1477,6 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 
 out_unlock:
 	spin_unlock_irq(q->queue_lock);
-out_unlock_rcu:
-	rcu_read_unlock();
 out:
 	/*
 	 * As multiple blk-throtls may stack in the same issue path, we
@@ -1667,7 +1562,7 @@ int blk_throtl_init(struct request_queue *q)
 		return -ENOMEM;
 
 	INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
-	throtl_service_queue_init(&td->service_queue, NULL);
+	throtl_service_queue_init(&td->service_queue);
 
 	q->td = td;
 	td->queue = q;

block/blk.h

@@ -272,15 +272,10 @@ static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
  * Internal throttling interface
  */
 #ifdef CONFIG_BLK_DEV_THROTTLING
-extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 extern void blk_throtl_drain(struct request_queue *q);
 extern int blk_throtl_init(struct request_queue *q);
 extern void blk_throtl_exit(struct request_queue *q);
 #else /* CONFIG_BLK_DEV_THROTTLING */
-static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
-{
-	return false;
-}
 static inline void blk_throtl_drain(struct request_queue *q) { }
 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 static inline void blk_throtl_exit(struct request_queue *q) { }

block/cfq-iosched.c

@@ -68,9 +68,9 @@ static struct kmem_cache *cfq_pool;
 #define rb_entry_cfqg(node)	rb_entry((node), struct cfq_group, rb_node)
 
 /* blkio-related constants */
-#define CFQ_WEIGHT_MIN          10
-#define CFQ_WEIGHT_MAX          1000
-#define CFQ_WEIGHT_DEFAULT      500
+#define CFQ_WEIGHT_LEGACY_MIN	10
+#define CFQ_WEIGHT_LEGACY_DFL	500
+#define CFQ_WEIGHT_LEGACY_MAX	1000
 
 struct cfq_ttime {
 	unsigned long last_end_request;
@@ -177,10 +177,6 @@ enum wl_type_t {
 
 struct cfqg_stats {
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
-	/* 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 */
@@ -189,8 +185,6 @@ struct cfqg_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;
 #ifdef CONFIG_DEBUG_BLK_CGROUP
@@ -220,7 +214,7 @@ struct cfqg_stats {
 /* Per-cgroup data */
 struct cfq_group_data {
 	/* must be the first member */
-	struct blkcg_policy_data pd;
+	struct blkcg_policy_data cpd;
 
 	unsigned int weight;
 	unsigned int leaf_weight;
@@ -304,7 +298,11 @@ struct cfq_group {
 	int dispatched;
 	struct cfq_ttime ttime;
 	struct cfqg_stats stats;	/* stats for this cfqg */
-	struct cfqg_stats dead_stats;	/* stats pushed from dead children */
+
+	/* async queue for each priority case */
+	struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
+	struct cfq_queue *async_idle_cfqq;
+
 };
 
 struct cfq_io_cq {
@@ -370,12 +368,6 @@ struct cfq_data {
 	struct cfq_queue *active_queue;
 	struct cfq_io_cq *active_cic;
 
-	/*
-	 * async queue for each priority case
-	 */
-	struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
-	struct cfq_queue *async_idle_cfqq;
-
 	sector_t last_position;
 
 	/*
@@ -401,6 +393,7 @@ struct cfq_data {
 };
 
 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
+static void cfq_put_queue(struct cfq_queue *cfqq);
 
 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
 					    enum wl_class_t class,
@@ -612,7 +605,7 @@ static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
 static struct cfq_group_data
 *cpd_to_cfqgd(struct blkcg_policy_data *cpd)
 {
-	return cpd ? container_of(cpd, struct cfq_group_data, pd) : NULL;
+	return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
 }
 
 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
@@ -693,14 +686,6 @@ static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
 	blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
 }
 
-static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
-					      uint64_t bytes, int rw)
-{
-	blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
-	blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
-	blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
-}
-
 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 			uint64_t start_time, uint64_t io_start_time, int rw)
 {
@@ -718,8 +703,6 @@ static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 static void cfqg_stats_reset(struct cfqg_stats *stats)
 {
 	/* 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);
@@ -736,28 +719,26 @@ static void cfqg_stats_reset(struct cfqg_stats *stats)
 }
 
 /* @to += @from */
-static void cfqg_stats_merge(struct cfqg_stats *to, struct cfqg_stats *from)
+static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
 {
 	/* queued stats shouldn't be cleared */
-	blkg_rwstat_merge(&to->service_bytes, &from->service_bytes);
-	blkg_rwstat_merge(&to->serviced, &from->serviced);
-	blkg_rwstat_merge(&to->merged, &from->merged);
-	blkg_rwstat_merge(&to->service_time, &from->service_time);
-	blkg_rwstat_merge(&to->wait_time, &from->wait_time);
-	blkg_stat_merge(&from->time, &from->time);
+	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);
 #ifdef CONFIG_DEBUG_BLK_CGROUP
-	blkg_stat_merge(&to->unaccounted_time, &from->unaccounted_time);
-	blkg_stat_merge(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
-	blkg_stat_merge(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
-	blkg_stat_merge(&to->dequeue, &from->dequeue);
-	blkg_stat_merge(&to->group_wait_time, &from->group_wait_time);
-	blkg_stat_merge(&to->idle_time, &from->idle_time);
-	blkg_stat_merge(&to->empty_time, &from->empty_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);
 #endif
 }
 
 /*
- * Transfer @cfqg's stats to its parent's dead_stats so that the ancestors'
+ * Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
  * recursive stats can still account for the amount used by this cfqg after
  * it's gone.
  */
@@ -770,10 +751,8 @@ static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
 	if (unlikely(!parent))
 		return;
 
-	cfqg_stats_merge(&parent->dead_stats, &cfqg->stats);
-	cfqg_stats_merge(&parent->dead_stats, &cfqg->dead_stats);
+	cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
 	cfqg_stats_reset(&cfqg->stats);
-	cfqg_stats_reset(&cfqg->dead_stats);
 }
 
 #else	/* CONFIG_CFQ_GROUP_IOSCHED */
@@ -795,8 +774,6 @@ static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
 			unsigned long time, unsigned long unaccounted_time) { }
 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
-static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
-					      uint64_t bytes, int rw) { }
 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 			uint64_t start_time, uint64_t io_start_time, int rw) { }
 
@@ -883,8 +860,7 @@ static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
 
 static void cfq_dispatch_insert(struct request_queue *, struct request *);
 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
-				       struct cfq_io_cq *cic, struct bio *bio,
-				       gfp_t gfp_mask);
+				       struct cfq_io_cq *cic, struct bio *bio);
 
 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
 {
@@ -1546,130 +1522,171 @@ static void cfq_init_cfqg_base(struct cfq_group *cfqg)
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
-static void cfqg_stats_init(struct cfqg_stats *stats)
+static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
+			    bool on_dfl, bool reset_dev, bool is_leaf_weight);
+
+static void cfqg_stats_exit(struct cfqg_stats *stats)
 {
-	blkg_rwstat_init(&stats->service_bytes);
-	blkg_rwstat_init(&stats->serviced);
-	blkg_rwstat_init(&stats->merged);
-	blkg_rwstat_init(&stats->service_time);
-	blkg_rwstat_init(&stats->wait_time);
-	blkg_rwstat_init(&stats->queued);
+	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->time);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+	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);
+#endif
+}
 
-	blkg_stat_init(&stats->sectors);
-	blkg_stat_init(&stats->time);
+static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t 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->time, gfp))
+		goto err;
 
 #ifdef CONFIG_DEBUG_BLK_CGROUP
-	blkg_stat_init(&stats->unaccounted_time);
-	blkg_stat_init(&stats->avg_queue_size_sum);
-	blkg_stat_init(&stats->avg_queue_size_samples);
-	blkg_stat_init(&stats->dequeue);
-	blkg_stat_init(&stats->group_wait_time);
-	blkg_stat_init(&stats->idle_time);
-	blkg_stat_init(&stats->empty_time);
+	if (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))
+		goto err;
 #endif
+	return 0;
+err:
+	cfqg_stats_exit(stats);
+	return -ENOMEM;
 }
 
-static void cfq_cpd_init(const struct blkcg *blkcg)
+static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
 {
-	struct cfq_group_data *cgd =
-		cpd_to_cfqgd(blkcg->pd[blkcg_policy_cfq.plid]);
+	struct cfq_group_data *cgd;
 
-	if (blkcg == &blkcg_root) {
-		cgd->weight = 2 * CFQ_WEIGHT_DEFAULT;
-		cgd->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
-	} else {
-		cgd->weight = CFQ_WEIGHT_DEFAULT;
-		cgd->leaf_weight = CFQ_WEIGHT_DEFAULT;
-	}
+	cgd = kzalloc(sizeof(*cgd), GFP_KERNEL);
+	if (!cgd)
+		return NULL;
+	return &cgd->cpd;
+}
+
+static void cfq_cpd_init(struct blkcg_policy_data *cpd)
+{
+	struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
+	unsigned int weight = cgroup_on_dfl(blkcg_root.css.cgroup) ?
+			      CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
+
+	if (cpd_to_blkcg(cpd) == &blkcg_root)
+		weight *= 2;
+
+	cgd->weight = weight;
+	cgd->leaf_weight = weight;
 }
 
-static void cfq_pd_init(struct blkcg_gq *blkg)
+static void cfq_cpd_free(struct blkcg_policy_data *cpd)
 {
-	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
-	struct cfq_group_data *cgd = blkcg_to_cfqgd(blkg->blkcg);
+	kfree(cpd_to_cfqgd(cpd));
+}
+
+static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
+{
+	struct blkcg *blkcg = cpd_to_blkcg(cpd);
+	bool on_dfl = cgroup_on_dfl(blkcg_root.css.cgroup);
+	unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
+
+	if (blkcg == &blkcg_root)
+		weight *= 2;
+
+	WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));
+	WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));
+}
+
+static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
+{
+	struct cfq_group *cfqg;
+
+	cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
+	if (!cfqg)
+		return NULL;
 
 	cfq_init_cfqg_base(cfqg);
+	if (cfqg_stats_init(&cfqg->stats, gfp)) {
+		kfree(cfqg);
+		return NULL;
+	}
+
+	return &cfqg->pd;
+}
+
+static void cfq_pd_init(struct blkg_policy_data *pd)
+{
+	struct cfq_group *cfqg = pd_to_cfqg(pd);
+	struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
+
 	cfqg->weight = cgd->weight;
 	cfqg->leaf_weight = cgd->leaf_weight;
-	cfqg_stats_init(&cfqg->stats);
-	cfqg_stats_init(&cfqg->dead_stats);
 }
 
-static void cfq_pd_offline(struct blkcg_gq *blkg)
+static void cfq_pd_offline(struct blkg_policy_data *pd)
 {
+	struct cfq_group *cfqg = pd_to_cfqg(pd);
+	int i;
+
+	for (i = 0; i < IOPRIO_BE_NR; i++) {
+		if (cfqg->async_cfqq[0][i])
+			cfq_put_queue(cfqg->async_cfqq[0][i]);
+		if (cfqg->async_cfqq[1][i])
+			cfq_put_queue(cfqg->async_cfqq[1][i]);
+	}
+
+	if (cfqg->async_idle_cfqq)
+		cfq_put_queue(cfqg->async_idle_cfqq);
+
 	/*
 	 * @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...
 	 */
-	cfqg_stats_xfer_dead(blkg_to_cfqg(blkg));
+	cfqg_stats_xfer_dead(cfqg);
 }
 
-/* offset delta from cfqg->stats to cfqg->dead_stats */
-static const int dead_stats_off_delta = offsetof(struct cfq_group, dead_stats) -
-					offsetof(struct cfq_group, stats);
-
-/* to be used by recursive prfill, sums live and dead stats recursively */
-static u64 cfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
+static void cfq_pd_free(struct blkg_policy_data *pd)
 {
-	u64 sum = 0;
-
-	sum += blkg_stat_recursive_sum(pd, off);
-	sum += blkg_stat_recursive_sum(pd, off + dead_stats_off_delta);
-	return sum;
-}
-
-/* to be used by recursive prfill, sums live and dead rwstats recursively */
-static struct blkg_rwstat cfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
-						       int off)
-{
-	struct blkg_rwstat a, b;
+	struct cfq_group *cfqg = pd_to_cfqg(pd);
 
-	a = blkg_rwstat_recursive_sum(pd, off);
-	b = blkg_rwstat_recursive_sum(pd, off + dead_stats_off_delta);
-	blkg_rwstat_merge(&a, &b);
-	return a;
+	cfqg_stats_exit(&cfqg->stats);
+	return kfree(cfqg);
 }
 
-static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
+static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
 {
-	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
+	struct cfq_group *cfqg = pd_to_cfqg(pd);
 
 	cfqg_stats_reset(&cfqg->stats);
-	cfqg_stats_reset(&cfqg->dead_stats);
 }
 
-/*
- * Search for the cfq group current task belongs to. request_queue lock must
- * be held.
- */
-static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
-						struct blkcg *blkcg)
+static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
+					 struct blkcg *blkcg)
 {
-	struct request_queue *q = cfqd->queue;
-	struct cfq_group *cfqg = NULL;
-
-	/* avoid lookup for the common case where there's no blkcg */
-	if (blkcg == &blkcg_root) {
-		cfqg = cfqd->root_group;
-	} else {
-		struct blkcg_gq *blkg;
-
-		blkg = blkg_lookup_create(blkcg, q);
-		if (!IS_ERR(blkg))
-			cfqg = blkg_to_cfqg(blkg);
-	}
+	struct blkcg_gq *blkg;
 
-	return cfqg;
+	blkg = blkg_lookup(blkcg, cfqd->queue);
+	if (likely(blkg))
+		return blkg_to_cfqg(blkg);
+	return NULL;
 }
 
 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
 {
-	/* Currently, all async queues are mapped to root group */
-	if (!cfq_cfqq_sync(cfqq))
-		cfqg = cfqq->cfqd->root_group;
-
 	cfqq->cfqg = cfqg;
 	/* cfqq reference on cfqg */
 	cfqg_get(cfqg);
@@ -1739,36 +1756,48 @@ static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
 
 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
 					char *buf, size_t nbytes, loff_t off,
-					bool is_leaf_weight)
+					bool on_dfl, bool is_leaf_weight)
 {
+	unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
+	unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
 	struct blkcg *blkcg = css_to_blkcg(of_css(of));
 	struct blkg_conf_ctx ctx;
 	struct cfq_group *cfqg;
 	struct cfq_group_data *cfqgd;
 	int ret;
+	u64 v;
 
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
 	if (ret)
 		return ret;
 
-	ret = -EINVAL;
+	if (sscanf(ctx.body, "%llu", &v) == 1) {
+		/* require "default" on dfl */
+		ret = -ERANGE;
+		if (!v && on_dfl)
+			goto out_finish;
+	} else if (!strcmp(strim(ctx.body), "default")) {
+		v = 0;
+	} else {
+		ret = -EINVAL;
+		goto out_finish;
+	}
+
 	cfqg = blkg_to_cfqg(ctx.blkg);
 	cfqgd = blkcg_to_cfqgd(blkcg);
-	if (!cfqg || !cfqgd)
-		goto err;
 
-	if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
+	ret = -ERANGE;
+	if (!v || (v >= min && v <= max)) {
 		if (!is_leaf_weight) {
-			cfqg->dev_weight = ctx.v;
-			cfqg->new_weight = ctx.v ?: cfqgd->weight;
+			cfqg->dev_weight = v;
+			cfqg->new_weight = v ?: cfqgd->weight;
 		} else {
-			cfqg->dev_leaf_weight = ctx.v;
-			cfqg->new_leaf_weight = ctx.v ?: cfqgd->leaf_weight;
+			cfqg->dev_leaf_weight = v;
+			cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
 		}
 		ret = 0;
 	}
-
-err:
+out_finish:
 	blkg_conf_finish(&ctx);
 	return ret ?: nbytes;
 }
@@ -1776,25 +1805,27 @@ static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
 				      char *buf, size_t nbytes, loff_t off)
 {
-	return __cfqg_set_weight_device(of, buf, nbytes, off, false);
+	return __cfqg_set_weight_device(of, buf, nbytes, off, false, false);
 }
 
 static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
 					   char *buf, size_t nbytes, loff_t off)
 {
-	return __cfqg_set_weight_device(of, buf, nbytes, off, true);
+	return __cfqg_set_weight_device(of, buf, nbytes, off, false, true);
 }
 
-static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
-			    u64 val, bool is_leaf_weight)
+static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
+			    bool on_dfl, bool reset_dev, bool is_leaf_weight)
 {
+	unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
+	unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
 	struct blkcg *blkcg = css_to_blkcg(css);
 	struct blkcg_gq *blkg;
 	struct cfq_group_data *cfqgd;
 	int ret = 0;
 
-	if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
-		return -EINVAL;
+	if (val < min || val > max)
+		return -ERANGE;
 
 	spin_lock_irq(&blkcg->lock);
 	cfqgd = blkcg_to_cfqgd(blkcg);
@@ -1815,9 +1846,13 @@ static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
 			continue;
 
 		if (!is_leaf_weight) {
+			if (reset_dev)
+				cfqg->dev_weight = 0;
 			if (!cfqg->dev_weight)
 				cfqg->new_weight = cfqgd->weight;
 		} else {
+			if (reset_dev)
+				cfqg->dev_leaf_weight = 0;
 			if (!cfqg->dev_leaf_weight)
 				cfqg->new_leaf_weight = cfqgd->leaf_weight;
 		}
@@ -1831,13 +1866,13 @@ static int __cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
 			  u64 val)
 {
-	return __cfq_set_weight(css, cft, val, false);
+	return __cfq_set_weight(css, val, false, false, false);
 }
 
 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
 			       struct cftype *cft, u64 val)
 {
-	return __cfq_set_weight(css, cft, val, true);
+	return __cfq_set_weight(css, val, false, false, true);
 }
 
 static int cfqg_print_stat(struct seq_file *sf, void *v)
@@ -1857,16 +1892,16 @@ static int cfqg_print_rwstat(struct seq_file *sf, void *v)
 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
 				      struct blkg_policy_data *pd, int off)
 {
-	u64 sum = cfqg_stat_pd_recursive_sum(pd, off);
-
+	u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
+					  &blkcg_policy_cfq, off);
 	return __blkg_prfill_u64(sf, pd, sum);
 }
 
 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
 					struct blkg_policy_data *pd, int off)
 {
-	struct blkg_rwstat sum = cfqg_rwstat_pd_recursive_sum(pd, off);
-
+	struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
+							&blkcg_policy_cfq, off);
 	return __blkg_prfill_rwstat(sf, pd, &sum);
 }
 
@@ -1886,6 +1921,40 @@ static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
 	return 0;
 }
 
+static u64 cfqg_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 cfqg_print_stat_sectors(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+			  cfqg_prfill_sectors, &blkcg_policy_cfq, 0, false);
+	return 0;
+}
+
+static u64 cfqg_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 cfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
+{
+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+			  cfqg_prfill_sectors_recursive, &blkcg_policy_cfq, 0,
+			  false);
+	return 0;
+}
+
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
 				      struct blkg_policy_data *pd, int off)
@@ -1912,7 +1981,7 @@ static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
 }
 #endif	/* CONFIG_DEBUG_BLK_CGROUP */
 
-static struct cftype cfq_blkcg_files[] = {
+static struct cftype cfq_blkcg_legacy_files[] = {
 	/* on root, weight is mapped to leaf_weight */
 	{
 		.name = "weight_device",
@@ -1960,18 +2029,17 @@ static struct cftype cfq_blkcg_files[] = {
 	},
 	{
 		.name = "sectors",
-		.private = offsetof(struct cfq_group, stats.sectors),
-		.seq_show = cfqg_print_stat,
+		.seq_show = cfqg_print_stat_sectors,
 	},
 	{
 		.name = "io_service_bytes",
-		.private = offsetof(struct cfq_group, stats.service_bytes),
-		.seq_show = cfqg_print_rwstat,
+		.private = (unsigned long)&blkcg_policy_cfq,
+		.seq_show = blkg_print_stat_bytes,
 	},
 	{
 		.name = "io_serviced",
-		.private = offsetof(struct cfq_group, stats.serviced),
-		.seq_show = cfqg_print_rwstat,
+		.private = (unsigned long)&blkcg_policy_cfq,
+		.seq_show = blkg_print_stat_ios,
 	},
 	{
 		.name = "io_service_time",
@@ -2002,18 +2070,17 @@ static struct cftype cfq_blkcg_files[] = {
 	},
 	{
 		.name = "sectors_recursive",
-		.private = offsetof(struct cfq_group, stats.sectors),
-		.seq_show = cfqg_print_stat_recursive,
+		.seq_show = cfqg_print_stat_sectors_recursive,
 	},
 	{
 		.name = "io_service_bytes_recursive",
-		.private = offsetof(struct cfq_group, stats.service_bytes),
-		.seq_show = cfqg_print_rwstat_recursive,
+		.private = (unsigned long)&blkcg_policy_cfq,
+		.seq_show = blkg_print_stat_bytes_recursive,
 	},
 	{
 		.name = "io_serviced_recursive",
-		.private = offsetof(struct cfq_group, stats.serviced),
-		.seq_show = cfqg_print_rwstat_recursive,
+		.private = (unsigned long)&blkcg_policy_cfq,
+		.seq_show = blkg_print_stat_ios_recursive,
 	},
 	{
 		.name = "io_service_time_recursive",
@@ -2068,9 +2135,51 @@ static struct cftype cfq_blkcg_files[] = {
 #endif	/* CONFIG_DEBUG_BLK_CGROUP */
 	{ }	/* terminate */
 };
+
+static int cfq_print_weight_on_dfl(struct seq_file *sf, void *v)
+{
+	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
+	struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
+
+	seq_printf(sf, "default %u\n", cgd->weight);
+	blkcg_print_blkgs(sf, blkcg, cfqg_prfill_weight_device,
+			  &blkcg_policy_cfq, 0, false);
+	return 0;
+}
+
+static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of,
+				     char *buf, size_t nbytes, loff_t off)
+{
+	char *endp;
+	int ret;
+	u64 v;
+
+	buf = strim(buf);
+
+	/* "WEIGHT" or "default WEIGHT" sets the default weight */
+	v = simple_strtoull(buf, &endp, 0);
+	if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
+		ret = __cfq_set_weight(of_css(of), v, true, false, false);
+		return ret ?: nbytes;
+	}
+
+	/* "MAJ:MIN WEIGHT" */
+	return __cfqg_set_weight_device(of, buf, nbytes, off, true, false);
+}
+
+static struct cftype cfq_blkcg_files[] = {
+	{
+		.name = "weight",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = cfq_print_weight_on_dfl,
+		.write = cfq_set_weight_on_dfl,
+	},
+	{ }	/* terminate */
+};
+
 #else /* GROUP_IOSCHED */
-static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
-						struct blkcg *blkcg)
+static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
+					 struct blkcg *blkcg)
 {
 	return cfqd->root_group;
 }
@@ -2873,7 +2982,6 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
 
 	cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
 	cfqq->nr_sectors += blk_rq_sectors(rq);
-	cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
 }
 
 /*
@@ -3506,14 +3614,14 @@ static void cfq_exit_icq(struct io_cq *icq)
 	struct cfq_io_cq *cic = icq_to_cic(icq);
 	struct cfq_data *cfqd = cic_to_cfqd(cic);
 
-	if (cic->cfqq[BLK_RW_ASYNC]) {
-		cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
-		cic->cfqq[BLK_RW_ASYNC] = NULL;
+	if (cic_to_cfqq(cic, false)) {
+		cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
+		cic_set_cfqq(cic, NULL, false);
 	}
 
-	if (cic->cfqq[BLK_RW_SYNC]) {
-		cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
-		cic->cfqq[BLK_RW_SYNC] = NULL;
+	if (cic_to_cfqq(cic, true)) {
+		cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
+		cic_set_cfqq(cic, NULL, true);
 	}
 }
 
@@ -3572,18 +3680,14 @@ static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
 	if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
 		return;
 
-	cfqq = cic->cfqq[BLK_RW_ASYNC];
+	cfqq = cic_to_cfqq(cic, false);
 	if (cfqq) {
-		struct cfq_queue *new_cfqq;
-		new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
-					 GFP_ATOMIC);
-		if (new_cfqq) {
-			cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
-			cfq_put_queue(cfqq);
-		}
+		cfq_put_queue(cfqq);
+		cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
+		cic_set_cfqq(cic, cfqq, false);
 	}
 
-	cfqq = cic->cfqq[BLK_RW_SYNC];
+	cfqq = cic_to_cfqq(cic, true);
 	if (cfqq)
 		cfq_mark_cfqq_prio_changed(cfqq);
 
@@ -3614,7 +3718,7 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
 {
 	struct cfq_data *cfqd = cic_to_cfqd(cic);
-	struct cfq_queue *sync_cfqq;
+	struct cfq_queue *cfqq;
 	uint64_t serial_nr;
 
 	rcu_read_lock();
@@ -3628,15 +3732,22 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
 	if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
 		return;
 
-	sync_cfqq = cic_to_cfqq(cic, 1);
-	if (sync_cfqq) {
-		/*
-		 * Drop reference to sync queue. A new sync queue will be
-		 * assigned in new group upon arrival of a fresh request.
-		 */
-		cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
-		cic_set_cfqq(cic, NULL, 1);
-		cfq_put_queue(sync_cfqq);
+	/*
+	 * Drop reference to queues.  New queues will be assigned in new
+	 * group upon arrival of fresh requests.
+	 */
+	cfqq = cic_to_cfqq(cic, false);
+	if (cfqq) {
+		cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
+		cic_set_cfqq(cic, NULL, false);
+		cfq_put_queue(cfqq);
+	}
+
+	cfqq = cic_to_cfqq(cic, true);
+	if (cfqq) {
+		cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
+		cic_set_cfqq(cic, NULL, true);
+		cfq_put_queue(cfqq);
 	}
 
 	cic->blkcg_serial_nr = serial_nr;
@@ -3645,81 +3756,19 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
 
-static struct cfq_queue *
-cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
-		     struct bio *bio, gfp_t gfp_mask)
-{
-	struct blkcg *blkcg;
-	struct cfq_queue *cfqq, *new_cfqq = NULL;
-	struct cfq_group *cfqg;
-
-retry:
-	rcu_read_lock();
-
-	blkcg = bio_blkcg(bio);
-	cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
-	if (!cfqg) {
-		cfqq = &cfqd->oom_cfqq;
-		goto out;
-	}
-
-	cfqq = cic_to_cfqq(cic, is_sync);
-
-	/*
-	 * Always try a new alloc if we fell back to the OOM cfqq
-	 * originally, since it should just be a temporary situation.
-	 */
-	if (!cfqq || cfqq == &cfqd->oom_cfqq) {
-		cfqq = NULL;
-		if (new_cfqq) {
-			cfqq = new_cfqq;
-			new_cfqq = NULL;
-		} else if (gfp_mask & __GFP_WAIT) {
-			rcu_read_unlock();
-			spin_unlock_irq(cfqd->queue->queue_lock);
-			new_cfqq = kmem_cache_alloc_node(cfq_pool,
-					gfp_mask | __GFP_ZERO,
-					cfqd->queue->node);
-			spin_lock_irq(cfqd->queue->queue_lock);
-			if (new_cfqq)
-				goto retry;
-			else
-				return &cfqd->oom_cfqq;
-		} else {
-			cfqq = kmem_cache_alloc_node(cfq_pool,
-					gfp_mask | __GFP_ZERO,
-					cfqd->queue->node);
-		}
-
-		if (cfqq) {
-			cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
-			cfq_init_prio_data(cfqq, cic);
-			cfq_link_cfqq_cfqg(cfqq, cfqg);
-			cfq_log_cfqq(cfqd, cfqq, "alloced");
-		} else
-			cfqq = &cfqd->oom_cfqq;
-	}
-out:
-	if (new_cfqq)
-		kmem_cache_free(cfq_pool, new_cfqq);
-
-	rcu_read_unlock();
-	return cfqq;
-}
-
 static struct cfq_queue **
-cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
+cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
 {
 	switch (ioprio_class) {
 	case IOPRIO_CLASS_RT:
-		return &cfqd->async_cfqq[0][ioprio];
+		return &cfqg->async_cfqq[0][ioprio];
 	case IOPRIO_CLASS_NONE:
 		ioprio = IOPRIO_NORM;
 		/* fall through */
 	case IOPRIO_CLASS_BE:
-		return &cfqd->async_cfqq[1][ioprio];
+		return &cfqg->async_cfqq[1][ioprio];
 	case IOPRIO_CLASS_IDLE:
-		return &cfqd->async_idle_cfqq;
+		return &cfqg->async_idle_cfqq;
 	default:
 		BUG();
 	}
@@ -3727,12 +3776,20 @@ cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
 
 static struct cfq_queue *
 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
-	      struct bio *bio, gfp_t gfp_mask)
+	      struct bio *bio)
 {
 	int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
 	int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
 	struct cfq_queue **async_cfqq = NULL;
-	struct cfq_queue *cfqq = NULL;
+	struct cfq_queue *cfqq;
+	struct cfq_group *cfqg;
+
+	rcu_read_lock();
+	cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
+	if (!cfqg) {
+		cfqq = &cfqd->oom_cfqq;
+		goto out;
+	}
 
 	if (!is_sync) {
 		if (!ioprio_valid(cic->ioprio)) {
@@ -3740,22 +3797,32 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
 			ioprio = task_nice_ioprio(tsk);
 			ioprio_class = task_nice_ioclass(tsk);
 		}
-		async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
+		async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
 		cfqq = *async_cfqq;
+		if (cfqq)
+			goto out;
 	}
 
-	if (!cfqq)
-		cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
+	cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
+				     cfqd->queue->node);
+	if (!cfqq) {
+		cfqq = &cfqd->oom_cfqq;
+		goto out;
+	}
 
-	/*
-	 * pin the queue now that it's allocated, scheduler exit will prune it
-	 */
-	if (!is_sync && !(*async_cfqq)) {
+	cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
+	cfq_init_prio_data(cfqq, cic);
+	cfq_link_cfqq_cfqg(cfqq, cfqg);
+	cfq_log_cfqq(cfqd, cfqq, "alloced");
+
+	if (async_cfqq) {
+		/* a new async queue is created, pin and remember */
 		cfqq->ref++;
 		*async_cfqq = cfqq;
 	}
-
+out:
 	cfqq->ref++;
+	rcu_read_unlock();
 	return cfqq;
 }
 
@@ -4289,8 +4356,6 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
 	const bool is_sync = rq_is_sync(rq);
 	struct cfq_queue *cfqq;
 
-	might_sleep_if(gfp_mask & __GFP_WAIT);
-
 	spin_lock_irq(q->queue_lock);
 
 	check_ioprio_changed(cic, bio);
@@ -4298,7 +4363,9 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
 new_queue:
 	cfqq = cic_to_cfqq(cic, is_sync);
 	if (!cfqq || cfqq == &cfqd->oom_cfqq) {
-		cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
+		if (cfqq)
+			cfq_put_queue(cfqq);
+		cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
 		cic_set_cfqq(cic, cfqq, is_sync);
 	} else {
 		/*
@@ -4404,21 +4471,6 @@ static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
 	cancel_work_sync(&cfqd->unplug_work);
 }
 
-static void cfq_put_async_queues(struct cfq_data *cfqd)
-{
-	int i;
-
-	for (i = 0; i < IOPRIO_BE_NR; i++) {
-		if (cfqd->async_cfqq[0][i])
-			cfq_put_queue(cfqd->async_cfqq[0][i]);
-		if (cfqd->async_cfqq[1][i])
-			cfq_put_queue(cfqd->async_cfqq[1][i]);
-	}
-
-	if (cfqd->async_idle_cfqq)
-		cfq_put_queue(cfqd->async_idle_cfqq);
-}
-
 static void cfq_exit_queue(struct elevator_queue *e)
 {
 	struct cfq_data *cfqd = e->elevator_data;
@@ -4431,8 +4483,6 @@ static void cfq_exit_queue(struct elevator_queue *e)
 	if (cfqd->active_queue)
 		__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
 
-	cfq_put_async_queues(cfqd);
-
 	spin_unlock_irq(q->queue_lock);
 
 	cfq_shutdown_timer_wq(cfqd);
@@ -4486,9 +4536,9 @@ static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
 		goto out_free;
 
 	cfq_init_cfqg_base(cfqd->root_group);
+	cfqd->root_group->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
+	cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
 #endif
-	cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
-	cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
 
 	/*
 	 * Not strictly needed (since RB_ROOT just clears the node and we
@@ -4499,7 +4549,7 @@ static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
 		cfqd->prio_trees[i] = RB_ROOT;
 
 	/*
-	 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
+	 * Our fallback cfqq if cfq_get_queue() runs into OOM issues.
 	 * Grab a permanent reference to it, so that the normal code flow
 	 * will not attempt to free it.  oom_cfqq is linked to root_group
 	 * but shouldn't hold a reference as it'll never be unlinked.  Lose
@@ -4683,13 +4733,18 @@ static struct elevator_type iosched_cfq = {
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
 static struct blkcg_policy blkcg_policy_cfq = {
-	.pd_size		= sizeof(struct cfq_group),
-	.cpd_size		= sizeof(struct cfq_group_data),
-	.cftypes		= cfq_blkcg_files,
+	.dfl_cftypes		= cfq_blkcg_files,
+	.legacy_cftypes		= cfq_blkcg_legacy_files,
 
+	.cpd_alloc_fn		= cfq_cpd_alloc,
 	.cpd_init_fn		= cfq_cpd_init,
+	.cpd_free_fn		= cfq_cpd_free,
+	.cpd_bind_fn		= cfq_cpd_bind,
+
+	.pd_alloc_fn		= cfq_pd_alloc,
 	.pd_init_fn		= cfq_pd_init,
 	.pd_offline_fn		= cfq_pd_offline,
+	.pd_free_fn		= cfq_pd_free,
 	.pd_reset_stats_fn	= cfq_pd_reset_stats,
 };
 #endif

fs/fs-writeback.c

@@ -53,8 +53,6 @@ struct wb_writeback_work {
 	unsigned int for_background:1;
 	unsigned int for_sync:1;	/* sync(2) WB_SYNC_ALL writeback */
 	unsigned int auto_free:1;	/* free on completion */
-	unsigned int single_wait:1;
-	unsigned int single_done:1;
 	enum wb_reason reason;		/* why was writeback initiated? */
 
 	struct list_head list;		/* pending work list */
@@ -178,14 +176,11 @@ static void wb_wakeup(struct bdi_writeback *wb)
 static void wb_queue_work(struct bdi_writeback *wb,
 			  struct wb_writeback_work *work)
 {
-	trace_writeback_queue(wb->bdi, work);
+	trace_writeback_queue(wb, work);
 
 	spin_lock_bh(&wb->work_lock);
-	if (!test_bit(WB_registered, &wb->state)) {
-		if (work->single_wait)
-			work->single_done = 1;
+	if (!test_bit(WB_registered, &wb->state))
 		goto out_unlock;
-	}
 	if (work->done)
 		atomic_inc(&work->done->cnt);
 	list_add_tail(&work->list, &wb->work_list);
@@ -706,7 +701,7 @@ EXPORT_SYMBOL_GPL(wbc_account_io);
 
 /**
  * inode_congested - test whether an inode is congested
- * @inode: inode to test for congestion
+ * @inode: inode to test for congestion (may be NULL)
  * @cong_bits: mask of WB_[a]sync_congested bits to test
  *
  * Tests whether @inode is congested.  @cong_bits is the mask of congestion
@@ -716,6 +711,9 @@ EXPORT_SYMBOL_GPL(wbc_account_io);
  * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg
  * associated with @inode is congested; otherwise, the root wb's congestion
  * state is used.
+ *
+ * @inode is allowed to be NULL as this function is often called on
+ * mapping->host which is NULL for the swapper space.
  */
 int inode_congested(struct inode *inode, int cong_bits)
 {
@@ -737,32 +735,6 @@ int inode_congested(struct inode *inode, int cong_bits)
 }
 EXPORT_SYMBOL_GPL(inode_congested);
 
-/**
- * wb_wait_for_single_work - wait for completion of a single bdi_writeback_work
- * @bdi: bdi the work item was issued to
- * @work: work item to wait for
- *
- * Wait for the completion of @work which was issued to one of @bdi's
- * bdi_writeback's.  The caller must have set @work->single_wait before
- * issuing it.  This wait operates independently fo
- * wb_wait_for_completion() and also disables automatic freeing of @work.
- */
-static void wb_wait_for_single_work(struct backing_dev_info *bdi,
-				    struct wb_writeback_work *work)
-{
-	if (WARN_ON_ONCE(!work->single_wait))
-		return;
-
-	wait_event(bdi->wb_waitq, work->single_done);
-
-	/*
-	 * Paired with smp_wmb() in wb_do_writeback() and ensures that all
-	 * modifications to @work prior to assertion of ->single_done is
-	 * visible to the caller once this function returns.
-	 */
-	smp_rmb();
-}
-
 /**
  * wb_split_bdi_pages - split nr_pages to write according to bandwidth
  * @wb: target bdi_writeback to split @nr_pages to
@@ -791,38 +763,6 @@ static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages)
 		return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw);
 }
 
-/**
- * wb_clone_and_queue_work - clone a wb_writeback_work and issue it to a wb
- * @wb: target bdi_writeback
- * @base_work: source wb_writeback_work
- *
- * Try to make a clone of @base_work and issue it to @wb.  If cloning
- * succeeds, %true is returned; otherwise, @base_work is issued directly
- * and %false is returned.  In the latter case, the caller is required to
- * wait for @base_work's completion using wb_wait_for_single_work().
- *
- * A clone is auto-freed on completion.  @base_work never is.
- */
-static bool wb_clone_and_queue_work(struct bdi_writeback *wb,
-				    struct wb_writeback_work *base_work)
-{
-	struct wb_writeback_work *work;
-
-	work = kmalloc(sizeof(*work), GFP_ATOMIC);
-	if (work) {
-		*work = *base_work;
-		work->auto_free = 1;
-		work->single_wait = 0;
-	} else {
-		work = base_work;
-		work->auto_free = 0;
-		work->single_wait = 1;
-	}
-	work->single_done = 0;
-	wb_queue_work(wb, work);
-	return work != base_work;
-}
-
 /**
  * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi
  * @bdi: target backing_dev_info
@@ -838,15 +778,19 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
 				  struct wb_writeback_work *base_work,
 				  bool skip_if_busy)
 {
-	long nr_pages = base_work->nr_pages;
-	int next_blkcg_id = 0;
+	int next_memcg_id = 0;
 	struct bdi_writeback *wb;
 	struct wb_iter iter;
 
 	might_sleep();
 restart:
 	rcu_read_lock();
-	bdi_for_each_wb(wb, bdi, &iter, next_blkcg_id) {
+	bdi_for_each_wb(wb, bdi, &iter, next_memcg_id) {
+		DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done);
+		struct wb_writeback_work fallback_work;
+		struct wb_writeback_work *work;
+		long nr_pages;
+
 		/* SYNC_ALL writes out I_DIRTY_TIME too */
 		if (!wb_has_dirty_io(wb) &&
 		    (base_work->sync_mode == WB_SYNC_NONE ||
@@ -855,13 +799,30 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
 		if (skip_if_busy && writeback_in_progress(wb))
 			continue;
 
-		base_work->nr_pages = wb_split_bdi_pages(wb, nr_pages);
-		if (!wb_clone_and_queue_work(wb, base_work)) {
-			next_blkcg_id = wb->blkcg_css->id + 1;
-			rcu_read_unlock();
-			wb_wait_for_single_work(bdi, base_work);
-			goto restart;
+		nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages);
+
+		work = kmalloc(sizeof(*work), GFP_ATOMIC);
+		if (work) {
+			*work = *base_work;
+			work->nr_pages = nr_pages;
+			work->auto_free = 1;
+			wb_queue_work(wb, work);
+			continue;
 		}
+
+		/* alloc failed, execute synchronously using on-stack fallback */
+		work = &fallback_work;
+		*work = *base_work;
+		work->nr_pages = nr_pages;
+		work->auto_free = 0;
+		work->done = &fallback_work_done;
+
+		wb_queue_work(wb, work);
+
+		next_memcg_id = wb->memcg_css->id + 1;
+		rcu_read_unlock();
+		wb_wait_for_completion(bdi, &fallback_work_done);
+		goto restart;
 	}
 	rcu_read_unlock();
 }
@@ -902,8 +863,6 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
 
 	if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) {
 		base_work->auto_free = 0;
-		base_work->single_wait = 0;
-		base_work->single_done = 0;
 		wb_queue_work(&bdi->wb, base_work);
 	}
 }
@@ -924,7 +883,7 @@ void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
 	 */
 	work = kzalloc(sizeof(*work), GFP_ATOMIC);
 	if (!work) {
-		trace_writeback_nowork(wb->bdi);
+		trace_writeback_nowork(wb);
 		wb_wakeup(wb);
 		return;
 	}
@@ -954,7 +913,7 @@ void wb_start_background_writeback(struct bdi_writeback *wb)
 	 * We just wake up the flusher thread. It will perform background
 	 * writeback as soon as there is no other work to do.
 	 */
-	trace_writeback_wake_background(wb->bdi);
+	trace_writeback_wake_background(wb);
 	wb_wakeup(wb);
 }
 
@@ -1660,14 +1619,14 @@ static long wb_writeback(struct bdi_writeback *wb,
 		} else if (work->for_background)
 			oldest_jif = jiffies;
 
-		trace_writeback_start(wb->bdi, work);
+		trace_writeback_start(wb, work);
 		if (list_empty(&wb->b_io))
 			queue_io(wb, work);
 		if (work->sb)
 			progress = writeback_sb_inodes(work->sb, wb, work);
 		else
 			progress = __writeback_inodes_wb(wb, work);
-		trace_writeback_written(wb->bdi, work);
+		trace_writeback_written(wb, work);
 
 		wb_update_bandwidth(wb, wb_start);
 
@@ -1692,7 +1651,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 		 * we'll just busyloop.
 		 */
 		if (!list_empty(&wb->b_more_io))  {
-			trace_writeback_wait(wb->bdi, work);
+			trace_writeback_wait(wb, work);
 			inode = wb_inode(wb->b_more_io.prev);
 			spin_lock(&inode->i_lock);
 			spin_unlock(&wb->list_lock);
@@ -1797,26 +1756,14 @@ static long wb_do_writeback(struct bdi_writeback *wb)
 	set_bit(WB_writeback_running, &wb->state);
 	while ((work = get_next_work_item(wb)) != NULL) {
 		struct wb_completion *done = work->done;
-		bool need_wake_up = false;
 
-		trace_writeback_exec(wb->bdi, work);
+		trace_writeback_exec(wb, work);
 
 		wrote += wb_writeback(wb, work);
 
-		if (work->single_wait) {
-			WARN_ON_ONCE(work->auto_free);
-			/* paired w/ rmb in wb_wait_for_single_work() */
-			smp_wmb();
-			work->single_done = 1;
-			need_wake_up = true;
-		} else if (work->auto_free) {
+		if (work->auto_free)
 			kfree(work);
-		}
-
 		if (done && atomic_dec_and_test(&done->cnt))
-			need_wake_up = true;
-
-		if (need_wake_up)
 			wake_up_all(&wb->bdi->wb_waitq);
 	}
 

fs/kernfs/dir.c

@@ -91,6 +91,29 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
 	return ret;
 }
 
+/**
+ * kernfs_path_len - determine the length of the full path of a given node
+ * @kn: kernfs_node of interest
+ *
+ * The returned length doesn't include the space for the terminating '\0'.
+ */
+size_t kernfs_path_len(struct kernfs_node *kn)
+{
+	size_t len = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&kernfs_rename_lock, flags);
+
+	do {
+		len += strlen(kn->name) + 1;
+		kn = kn->parent;
+	} while (kn && kn->parent);
+
+	spin_unlock_irqrestore(&kernfs_rename_lock, flags);
+
+	return len;
+}
+
 /**
  * kernfs_path - build full path of a given node
  * @kn: kernfs_node of interest

include/linux/backing-dev.h

@@ -286,7 +286,7 @@ static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi
 	 * %current's blkcg equals the effective blkcg of its memcg.  No
 	 * need to use the relatively expensive cgroup_get_e_css().
 	 */
-	if (likely(wb && wb->blkcg_css == task_css(current, blkio_cgrp_id)))
+	if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
 		return wb;
 	return NULL;
 }
@@ -402,7 +402,7 @@ static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
 }
 
 struct wb_iter {
-	int			start_blkcg_id;
+	int			start_memcg_id;
 	struct radix_tree_iter	tree_iter;
 	void			**slot;
 };
@@ -414,9 +414,9 @@ static inline struct bdi_writeback *__wb_iter_next(struct wb_iter *iter,
 
 	WARN_ON_ONCE(!rcu_read_lock_held());
 
-	if (iter->start_blkcg_id >= 0) {
-		iter->slot = radix_tree_iter_init(titer, iter->start_blkcg_id);
-		iter->start_blkcg_id = -1;
+	if (iter->start_memcg_id >= 0) {
+		iter->slot = radix_tree_iter_init(titer, iter->start_memcg_id);
+		iter->start_memcg_id = -1;
 	} else {
 		iter->slot = radix_tree_next_slot(iter->slot, titer, 0);
 	}
@@ -430,30 +430,30 @@ static inline struct bdi_writeback *__wb_iter_next(struct wb_iter *iter,
 
 static inline struct bdi_writeback *__wb_iter_init(struct wb_iter *iter,
 						   struct backing_dev_info *bdi,
-						   int start_blkcg_id)
+						   int start_memcg_id)
 {
-	iter->start_blkcg_id = start_blkcg_id;
+	iter->start_memcg_id = start_memcg_id;
 
-	if (start_blkcg_id)
+	if (start_memcg_id)
 		return __wb_iter_next(iter, bdi);
 	else
 		return &bdi->wb;
 }
 
 /**
- * bdi_for_each_wb - walk all wb's of a bdi in ascending blkcg ID order
+ * bdi_for_each_wb - walk all wb's of a bdi in ascending memcg ID order
  * @wb_cur: cursor struct bdi_writeback pointer
  * @bdi: bdi to walk wb's of
  * @iter: pointer to struct wb_iter to be used as iteration buffer
- * @start_blkcg_id: blkcg ID to start iteration from
+ * @start_memcg_id: memcg ID to start iteration from
  *
  * Iterate @wb_cur through the wb's (bdi_writeback's) of @bdi in ascending
- * blkcg ID order starting from @start_blkcg_id.  @iter is struct wb_iter
+ * memcg ID order starting from @start_memcg_id.  @iter is struct wb_iter
  * to be used as temp storage during iteration.  rcu_read_lock() must be
  * held throughout iteration.
  */
-#define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id)		\
-	for ((wb_cur) = __wb_iter_init(iter, bdi, start_blkcg_id);	\
+#define bdi_for_each_wb(wb_cur, bdi, iter, start_memcg_id)		\
+	for ((wb_cur) = __wb_iter_init(iter, bdi, start_memcg_id);	\
 	     (wb_cur); (wb_cur) = __wb_iter_next(iter, bdi))
 
 #else	/* CONFIG_CGROUP_WRITEBACK */

include/linux/blk-cgroup.h

@@ -14,12 +14,15 @@
  */
 
 #include <linux/cgroup.h>
-#include <linux/u64_stats_sync.h>
+#include <linux/percpu_counter.h>
 #include <linux/seq_file.h>
 #include <linux/radix-tree.h>
 #include <linux/blkdev.h>
 #include <linux/atomic.h>
 
+/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
+#define BLKG_STAT_CPU_BATCH	(INT_MAX / 2)
+
 /* Max limits for throttle policy */
 #define THROTL_IOPS_MAX		UINT_MAX
 
@@ -45,7 +48,7 @@ struct blkcg {
 	struct blkcg_gq			*blkg_hint;
 	struct hlist_head		blkg_list;
 
-	struct blkcg_policy_data	*pd[BLKCG_MAX_POLS];
+	struct blkcg_policy_data	*cpd[BLKCG_MAX_POLS];
 
 	struct list_head		all_blkcgs_node;
 #ifdef CONFIG_CGROUP_WRITEBACK
@@ -53,14 +56,19 @@ struct blkcg {
 #endif
 };
 
+/*
+ * blkg_[rw]stat->aux_cnt is excluded for local stats but included for
+ * recursive.  Used to carry stats of dead children, and, for blkg_rwstat,
+ * to carry result values from read and sum operations.
+ */
 struct blkg_stat {
-	struct u64_stats_sync		syncp;
-	uint64_t			cnt;
+	struct percpu_counter		cpu_cnt;
+	atomic64_t			aux_cnt;
 };
 
 struct blkg_rwstat {
-	struct u64_stats_sync		syncp;
-	uint64_t			cnt[BLKG_RWSTAT_NR];
+	struct percpu_counter		cpu_cnt[BLKG_RWSTAT_NR];
+	atomic64_t			aux_cnt[BLKG_RWSTAT_NR];
 };
 
 /*
@@ -68,32 +76,28 @@ struct blkg_rwstat {
  * request_queue (q).  This is used by blkcg policies which need to track
  * information per blkcg - q pair.
  *
- * There can be multiple active blkcg policies and each has its private
- * data on each blkg, the size of which is determined by
- * blkcg_policy->pd_size.  blkcg core allocates and frees such areas
- * together with blkg and invokes pd_init/exit_fn() methods.
- *
- * Such private data must embed struct blkg_policy_data (pd) at the
- * beginning and pd_size can't be smaller than pd.
+ * There can be multiple active blkcg policies and each blkg:policy pair is
+ * represented by a blkg_policy_data which is allocated and freed by each
+ * policy's pd_alloc/free_fn() methods.  A policy can allocate private data
+ * area by allocating larger data structure which embeds blkg_policy_data
+ * at the beginning.
  */
 struct blkg_policy_data {
 	/* the blkg and policy id this per-policy data belongs to */
 	struct blkcg_gq			*blkg;
 	int				plid;
-
-	/* used during policy activation */
-	struct list_head		alloc_node;
 };
 
 /*
- * Policies that need to keep per-blkcg data which is independent
- * from any request_queue associated to it must specify its size
- * with the cpd_size field of the blkcg_policy structure and
- * embed a blkcg_policy_data in it.  cpd_init() is invoked to let
- * each policy handle per-blkcg data.
+ * Policies that need to keep per-blkcg data which is independent from any
+ * request_queue associated to it should implement cpd_alloc/free_fn()
+ * methods.  A policy can allocate private data area by allocating larger
+ * data structure which embeds blkcg_policy_data at the beginning.
+ * cpd_init() is invoked to let each policy handle per-blkcg data.
  */
 struct blkcg_policy_data {
-	/* the policy id this per-policy data belongs to */
+	/* the blkcg and policy id this per-policy data belongs to */
+	struct blkcg			*blkcg;
 	int				plid;
 };
 
@@ -123,40 +127,50 @@ struct blkcg_gq {
 	/* is this blkg online? protected by both blkcg and q locks */
 	bool				online;
 
+	struct blkg_rwstat		stat_bytes;
+	struct blkg_rwstat		stat_ios;
+
 	struct blkg_policy_data		*pd[BLKCG_MAX_POLS];
 
 	struct rcu_head			rcu_head;
 };
 
-typedef void (blkcg_pol_init_cpd_fn)(const struct blkcg *blkcg);
-typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
-typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
-typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
-typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
-typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
+typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
+typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
+typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
+typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
+typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
+typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
+typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
+typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
+typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
+typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
 
 struct blkcg_policy {
 	int				plid;
-	/* policy specific private data size */
-	size_t				pd_size;
-	/* policy specific per-blkcg data size */
-	size_t				cpd_size;
 	/* cgroup files for the policy */
-	struct cftype			*cftypes;
+	struct cftype			*dfl_cftypes;
+	struct cftype			*legacy_cftypes;
 
 	/* operations */
+	blkcg_pol_alloc_cpd_fn		*cpd_alloc_fn;
 	blkcg_pol_init_cpd_fn		*cpd_init_fn;
+	blkcg_pol_free_cpd_fn		*cpd_free_fn;
+	blkcg_pol_bind_cpd_fn		*cpd_bind_fn;
+
+	blkcg_pol_alloc_pd_fn		*pd_alloc_fn;
 	blkcg_pol_init_pd_fn		*pd_init_fn;
 	blkcg_pol_online_pd_fn		*pd_online_fn;
 	blkcg_pol_offline_pd_fn		*pd_offline_fn;
-	blkcg_pol_exit_pd_fn		*pd_exit_fn;
+	blkcg_pol_free_pd_fn		*pd_free_fn;
 	blkcg_pol_reset_pd_stats_fn	*pd_reset_stats_fn;
 };
 
 extern struct blkcg blkcg_root;
 extern struct cgroup_subsys_state * const blkcg_root_css;
 
-struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
+struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
+				      struct request_queue *q, bool update_hint);
 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 				    struct request_queue *q);
 int blkcg_init_queue(struct request_queue *q);
@@ -171,6 +185,7 @@ int blkcg_activate_policy(struct request_queue *q,
 void blkcg_deactivate_policy(struct request_queue *q,
 			     const struct blkcg_policy *pol);
 
+const char *blkg_dev_name(struct blkcg_gq *blkg);
 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 		       u64 (*prfill)(struct seq_file *,
 				     struct blkg_policy_data *, int),
@@ -182,19 +197,24 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 		       int off);
+int blkg_print_stat_bytes(struct seq_file *sf, void *v);
+int blkg_print_stat_ios(struct seq_file *sf, void *v);
+int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
+int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
 
-u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
-struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
-					     int off);
+u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
+			    struct blkcg_policy *pol, int off);
+struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
+					     struct blkcg_policy *pol, int off);
 
 struct blkg_conf_ctx {
 	struct gendisk			*disk;
 	struct blkcg_gq			*blkg;
-	u64				v;
+	char				*body;
 };
 
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
-		   const char *input, struct blkg_conf_ctx *ctx);
+		   char *input, struct blkg_conf_ctx *ctx);
 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 
 
@@ -205,7 +225,7 @@ static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
 
 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 {
-	return css_to_blkcg(task_css(tsk, blkio_cgrp_id));
+	return css_to_blkcg(task_css(tsk, io_cgrp_id));
 }
 
 static inline struct blkcg *bio_blkcg(struct bio *bio)
@@ -218,7 +238,7 @@ static inline struct blkcg *bio_blkcg(struct bio *bio)
 static inline struct cgroup_subsys_state *
 task_get_blkcg_css(struct task_struct *task)
 {
-	return task_get_css(task, blkio_cgrp_id);
+	return task_get_css(task, io_cgrp_id);
 }
 
 /**
@@ -232,6 +252,52 @@ static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 	return css_to_blkcg(blkcg->css.parent);
 }
 
+/**
+ * __blkg_lookup - internal version of blkg_lookup()
+ * @blkcg: blkcg of interest
+ * @q: request_queue of interest
+ * @update_hint: whether to update lookup hint with the result or not
+ *
+ * This is internal version and shouldn't be used by policy
+ * implementations.  Looks up blkgs for the @blkcg - @q pair regardless of
+ * @q's bypass state.  If @update_hint is %true, the caller should be
+ * holding @q->queue_lock and lookup hint is updated on success.
+ */
+static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
+					     struct request_queue *q,
+					     bool update_hint)
+{
+	struct blkcg_gq *blkg;
+
+	if (blkcg == &blkcg_root)
+		return q->root_blkg;
+
+	blkg = rcu_dereference(blkcg->blkg_hint);
+	if (blkg && blkg->q == q)
+		return blkg;
+
+	return blkg_lookup_slowpath(blkcg, q, update_hint);
+}
+
+/**
+ * blkg_lookup - lookup blkg for the specified blkcg - q pair
+ * @blkcg: blkcg of interest
+ * @q: request_queue of interest
+ *
+ * Lookup blkg for the @blkcg - @q pair.  This function should be called
+ * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
+ * - see blk_queue_bypass_start() for details.
+ */
+static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
+					   struct request_queue *q)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	if (unlikely(blk_queue_bypass(q)))
+		return NULL;
+	return __blkg_lookup(blkcg, q, false);
+}
+
 /**
  * blkg_to_pdata - get policy private data
  * @blkg: blkg of interest
@@ -248,7 +314,7 @@ static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
 						     struct blkcg_policy *pol)
 {
-	return blkcg ? blkcg->pd[pol->plid] : NULL;
+	return blkcg ? blkcg->cpd[pol->plid] : NULL;
 }
 
 /**
@@ -262,6 +328,11 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 	return pd ? pd->blkg : NULL;
 }
 
+static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
+{
+	return cpd ? cpd->blkcg : NULL;
+}
+
 /**
  * blkg_path - format cgroup path of blkg
  * @blkg: blkg of interest
@@ -309,9 +380,6 @@ static inline void blkg_put(struct blkcg_gq *blkg)
 		call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 }
 
-struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
-			       bool update_hint);
-
 /**
  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
  * @d_blkg: loop cursor pointing to the current descendant
@@ -373,8 +441,8 @@ static inline struct request_list *blk_get_rl(struct request_queue *q,
 	 * or if either the blkcg or queue is going away.  Fall back to
 	 * root_rl in such cases.
 	 */
-	blkg = blkg_lookup_create(blkcg, q);
-	if (IS_ERR(blkg))
+	blkg = blkg_lookup(blkcg, q);
+	if (unlikely(!blkg))
 		goto root_rl;
 
 	blkg_get(blkg);
@@ -394,8 +462,7 @@ static inline struct request_list *blk_get_rl(struct request_queue *q,
  */
 static inline void blk_put_rl(struct request_list *rl)
 {
-	/* root_rl may not have blkg set */
-	if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
+	if (rl->blkg->blkcg != &blkcg_root)
 		blkg_put(rl->blkg);
 }
 
@@ -433,9 +500,21 @@ struct request_list *__blk_queue_next_rl(struct request_list *rl,
 #define blk_queue_for_each_rl(rl, q)	\
 	for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 
-static inline void blkg_stat_init(struct blkg_stat *stat)
+static inline int blkg_stat_init(struct blkg_stat *stat, gfp_t gfp)
 {
-	u64_stats_init(&stat->syncp);
+	int ret;
+
+	ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
+	if (ret)
+		return ret;
+
+	atomic64_set(&stat->aux_cnt, 0);
+	return 0;
+}
+
+static inline void blkg_stat_exit(struct blkg_stat *stat)
+{
+	percpu_counter_destroy(&stat->cpu_cnt);
 }
 
 /**
@@ -443,34 +522,21 @@ static inline void blkg_stat_init(struct blkg_stat *stat)
  * @stat: target blkg_stat
  * @val: value to add
  *
- * Add @val to @stat.  The caller is responsible for synchronizing calls to
- * this function.
+ * Add @val to @stat.  The caller must ensure that IRQ on the same CPU
+ * don't re-enter this function for the same counter.
  */
 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 {
-	u64_stats_update_begin(&stat->syncp);
-	stat->cnt += val;
-	u64_stats_update_end(&stat->syncp);
+	__percpu_counter_add(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
 }
 
 /**
  * blkg_stat_read - read the current value of a blkg_stat
  * @stat: blkg_stat to read
- *
- * Read the current value of @stat.  This function can be called without
- * synchroniztion and takes care of u64 atomicity.
  */
 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 {
-	unsigned int start;
-	uint64_t v;
-
-	do {
-		start = u64_stats_fetch_begin_irq(&stat->syncp);
-		v = stat->cnt;
-	} while (u64_stats_fetch_retry_irq(&stat->syncp, start));
-
-	return v;
+	return percpu_counter_sum_positive(&stat->cpu_cnt);
 }
 
 /**
@@ -479,24 +545,46 @@ static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
  */
 static inline void blkg_stat_reset(struct blkg_stat *stat)
 {
-	stat->cnt = 0;
+	percpu_counter_set(&stat->cpu_cnt, 0);
+	atomic64_set(&stat->aux_cnt, 0);
 }
 
 /**
- * blkg_stat_merge - merge a blkg_stat into another
+ * blkg_stat_add_aux - add a blkg_stat into another's aux count
  * @to: the destination blkg_stat
  * @from: the source
  *
- * Add @from's count to @to.
+ * Add @from's count including the aux one to @to's aux count.
  */
-static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
+static inline void blkg_stat_add_aux(struct blkg_stat *to,
+				     struct blkg_stat *from)
 {
-	blkg_stat_add(to, blkg_stat_read(from));
+	atomic64_add(blkg_stat_read(from) + atomic64_read(&from->aux_cnt),
+		     &to->aux_cnt);
 }
 
-static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
+static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
 {
-	u64_stats_init(&rwstat->syncp);
+	int i, ret;
+
+	for (i = 0; i < BLKG_RWSTAT_NR; i++) {
+		ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
+		if (ret) {
+			while (--i >= 0)
+				percpu_counter_destroy(&rwstat->cpu_cnt[i]);
+			return ret;
+		}
+		atomic64_set(&rwstat->aux_cnt[i], 0);
+	}
+	return 0;
+}
+
+static inline void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
+{
+	int i;
+
+	for (i = 0; i < BLKG_RWSTAT_NR; i++)
+		percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 }
 
 /**
@@ -511,39 +599,38 @@ static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 				   int rw, uint64_t val)
 {
-	u64_stats_update_begin(&rwstat->syncp);
+	struct percpu_counter *cnt;
 
 	if (rw & REQ_WRITE)
-		rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
+		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
 	else
-		rwstat->cnt[BLKG_RWSTAT_READ] += val;
+		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
+
+	__percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
+
 	if (rw & REQ_SYNC)
-		rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
+		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
 	else
-		rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
+		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
 
-	u64_stats_update_end(&rwstat->syncp);
+	__percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
 }
 
 /**
  * blkg_rwstat_read - read the current values of a blkg_rwstat
  * @rwstat: blkg_rwstat to read
  *
- * Read the current snapshot of @rwstat and return it as the return value.
- * This function can be called without synchronization and takes care of
- * u64 atomicity.
+ * Read the current snapshot of @rwstat and return it in the aux counts.
  */
 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 {
-	unsigned int start;
-	struct blkg_rwstat tmp;
-
-	do {
-		start = u64_stats_fetch_begin_irq(&rwstat->syncp);
-		tmp = *rwstat;
-	} while (u64_stats_fetch_retry_irq(&rwstat->syncp, start));
+	struct blkg_rwstat result;
+	int i;
 
-	return tmp;
+	for (i = 0; i < BLKG_RWSTAT_NR; i++)
+		atomic64_set(&result.aux_cnt[i],
+			     percpu_counter_sum_positive(&rwstat->cpu_cnt[i]));
+	return result;
 }
 
 /**
@@ -558,7 +645,8 @@ static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
 {
 	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 
-	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
+	return atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
+		atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
 }
 
 /**
@@ -567,26 +655,71 @@ static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
  */
 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 {
-	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
+	int i;
+
+	for (i = 0; i < BLKG_RWSTAT_NR; i++) {
+		percpu_counter_set(&rwstat->cpu_cnt[i], 0);
+		atomic64_set(&rwstat->aux_cnt[i], 0);
+	}
 }
 
 /**
- * blkg_rwstat_merge - merge a blkg_rwstat into another
+ * blkg_rwstat_add_aux - add a blkg_rwstat into another's aux count
  * @to: the destination blkg_rwstat
  * @from: the source
  *
- * Add @from's counts to @to.
+ * Add @from's count including the aux one to @to's aux count.
  */
-static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
-				     struct blkg_rwstat *from)
+static inline void blkg_rwstat_add_aux(struct blkg_rwstat *to,
+				       struct blkg_rwstat *from)
 {
 	struct blkg_rwstat v = blkg_rwstat_read(from);
 	int i;
 
-	u64_stats_update_begin(&to->syncp);
 	for (i = 0; i < BLKG_RWSTAT_NR; i++)
-		to->cnt[i] += v.cnt[i];
-	u64_stats_update_end(&to->syncp);
+		atomic64_add(atomic64_read(&v.aux_cnt[i]) +
+			     atomic64_read(&from->aux_cnt[i]),
+			     &to->aux_cnt[i]);
+}
+
+#ifdef CONFIG_BLK_DEV_THROTTLING
+extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
+			   struct bio *bio);
+#else
+static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
+				  struct bio *bio) { return false; }
+#endif
+
+static inline bool blkcg_bio_issue_check(struct request_queue *q,
+					 struct bio *bio)
+{
+	struct blkcg *blkcg;
+	struct blkcg_gq *blkg;
+	bool throtl = false;
+
+	rcu_read_lock();
+	blkcg = bio_blkcg(bio);
+
+	blkg = blkg_lookup(blkcg, q);
+	if (unlikely(!blkg)) {
+		spin_lock_irq(q->queue_lock);
+		blkg = blkg_lookup_create(blkcg, q);
+		if (IS_ERR(blkg))
+			blkg = NULL;
+		spin_unlock_irq(q->queue_lock);
+	}
+
+	throtl = blk_throtl_bio(q, blkg, bio);
+
+	if (!throtl) {
+		blkg = blkg ?: q->root_blkg;
+		blkg_rwstat_add(&blkg->stat_bytes, bio->bi_flags,
+				bio->bi_iter.bi_size);
+		blkg_rwstat_add(&blkg->stat_ios, bio->bi_flags, 1);
+	}
+
+	rcu_read_unlock();
+	return !throtl;
 }
 
 #else	/* CONFIG_BLK_CGROUP */
@@ -642,6 +775,9 @@ static inline void blk_put_rl(struct request_list *rl) { }
 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 
+static inline bool blkcg_bio_issue_check(struct request_queue *q,
+					 struct bio *bio) { return true; }
+
 #define blk_queue_for_each_rl(rl, q)	\
 	for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 

include/linux/cgroup_subsys.h

@@ -27,7 +27,7 @@ SUBSYS(cpuacct)
 #endif
 
 #if IS_ENABLED(CONFIG_BLK_CGROUP)
-SUBSYS(blkio)
+SUBSYS(io)
 #endif
 
 #if IS_ENABLED(CONFIG_MEMCG)

include/linux/kernfs.h

@@ -266,6 +266,7 @@ static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
 }
 
 int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen);
+size_t kernfs_path_len(struct kernfs_node *kn);
 char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
 				size_t buflen);
 void pr_cont_kernfs_name(struct kernfs_node *kn);
@@ -332,6 +333,9 @@ static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
 static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
 { return -ENOSYS; }
 
+static inline size_t kernfs_path_len(struct kernfs_node *kn)
+{ return 0; }
+
 static inline char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
 					      size_t buflen)
 { return NULL; }

include/trace/events/writeback.h

@@ -131,6 +131,66 @@ DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,
 	TP_ARGS(inode, flags)
 );
 
+#ifdef CREATE_TRACE_POINTS
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+static inline size_t __trace_wb_cgroup_size(struct bdi_writeback *wb)
+{
+	return kernfs_path_len(wb->memcg_css->cgroup->kn) + 1;
+}
+
+static inline void __trace_wb_assign_cgroup(char *buf, struct bdi_writeback *wb)
+{
+	struct cgroup *cgrp = wb->memcg_css->cgroup;
+	char *path;
+
+	path = cgroup_path(cgrp, buf, kernfs_path_len(cgrp->kn) + 1);
+	WARN_ON_ONCE(path != buf);
+}
+
+static inline size_t __trace_wbc_cgroup_size(struct writeback_control *wbc)
+{
+	if (wbc->wb)
+		return __trace_wb_cgroup_size(wbc->wb);
+	else
+		return 2;
+}
+
+static inline void __trace_wbc_assign_cgroup(char *buf,
+					     struct writeback_control *wbc)
+{
+	if (wbc->wb)
+		__trace_wb_assign_cgroup(buf, wbc->wb);
+	else
+		strcpy(buf, "/");
+}
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+static inline size_t __trace_wb_cgroup_size(struct bdi_writeback *wb)
+{
+	return 2;
+}
+
+static inline void __trace_wb_assign_cgroup(char *buf, struct bdi_writeback *wb)
+{
+	strcpy(buf, "/");
+}
+
+static inline size_t __trace_wbc_cgroup_size(struct writeback_control *wbc)
+{
+	return 2;
+}
+
+static inline void __trace_wbc_assign_cgroup(char *buf,
+					     struct writeback_control *wbc)
+{
+	strcpy(buf, "/");
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+#endif	/* CREATE_TRACE_POINTS */
+
 DECLARE_EVENT_CLASS(writeback_write_inode_template,
 
 	TP_PROTO(struct inode *inode, struct writeback_control *wbc),
@@ -141,6 +201,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
 		__array(char, name, 32)
 		__field(unsigned long, ino)
 		__field(int, sync_mode)
+		__dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
 	),
 
 	TP_fast_assign(
@@ -148,12 +209,14 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
 			dev_name(inode_to_bdi(inode)->dev), 32);
 		__entry->ino		= inode->i_ino;
 		__entry->sync_mode	= wbc->sync_mode;
+		__trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
 	),
 
-	TP_printk("bdi %s: ino=%lu sync_mode=%d",
+	TP_printk("bdi %s: ino=%lu sync_mode=%d cgroup=%s",
 		__entry->name,
 		__entry->ino,
-		__entry->sync_mode
+		__entry->sync_mode,
+		__get_str(cgroup)
 	)
 );
 
@@ -172,8 +235,8 @@ DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode,
 );
 
 DECLARE_EVENT_CLASS(writeback_work_class,
-	TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work),
-	TP_ARGS(bdi, work),
+	TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work),
+	TP_ARGS(wb, work),
 	TP_STRUCT__entry(
 		__array(char, name, 32)
 		__field(long, nr_pages)
@@ -183,10 +246,11 @@ DECLARE_EVENT_CLASS(writeback_work_class,
 		__field(int, range_cyclic)
 		__field(int, for_background)
 		__field(int, reason)
+		__dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
 	),
 	TP_fast_assign(
 		strncpy(__entry->name,
-			bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+			wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
 		__entry->nr_pages = work->nr_pages;
 		__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
 		__entry->sync_mode = work->sync_mode;
@@ -194,9 +258,10 @@ DECLARE_EVENT_CLASS(writeback_work_class,
 		__entry->range_cyclic = work->range_cyclic;
 		__entry->for_background	= work->for_background;
 		__entry->reason = work->reason;
+		__trace_wb_assign_cgroup(__get_str(cgroup), wb);
 	),
 	TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d "
-		  "kupdate=%d range_cyclic=%d background=%d reason=%s",
+		  "kupdate=%d range_cyclic=%d background=%d reason=%s cgroup=%s",
 		  __entry->name,
 		  MAJOR(__entry->sb_dev), MINOR(__entry->sb_dev),
 		  __entry->nr_pages,
@@ -204,13 +269,14 @@ DECLARE_EVENT_CLASS(writeback_work_class,
 		  __entry->for_kupdate,
 		  __entry->range_cyclic,
 		  __entry->for_background,
-		  __print_symbolic(__entry->reason, WB_WORK_REASON)
+		  __print_symbolic(__entry->reason, WB_WORK_REASON),
+		  __get_str(cgroup)
 	)
 );
 #define DEFINE_WRITEBACK_WORK_EVENT(name) \
 DEFINE_EVENT(writeback_work_class, name, \
-	TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work), \
-	TP_ARGS(bdi, work))
+	TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work), \
+	TP_ARGS(wb, work))
 DEFINE_WRITEBACK_WORK_EVENT(writeback_queue);
 DEFINE_WRITEBACK_WORK_EVENT(writeback_exec);
 DEFINE_WRITEBACK_WORK_EVENT(writeback_start);
@@ -230,26 +296,42 @@ TRACE_EVENT(writeback_pages_written,
 );
 
 DECLARE_EVENT_CLASS(writeback_class,
-	TP_PROTO(struct backing_dev_info *bdi),
-	TP_ARGS(bdi),
+	TP_PROTO(struct bdi_writeback *wb),
+	TP_ARGS(wb),
 	TP_STRUCT__entry(
 		__array(char, name, 32)
+		__dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
 	),
 	TP_fast_assign(
-		strncpy(__entry->name, dev_name(bdi->dev), 32);
+		strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+		__trace_wb_assign_cgroup(__get_str(cgroup), wb);
 	),
-	TP_printk("bdi %s",
-		  __entry->name
+	TP_printk("bdi %s: cgroup=%s",
+		  __entry->name,
+		  __get_str(cgroup)
 	)
 );
 #define DEFINE_WRITEBACK_EVENT(name) \
 DEFINE_EVENT(writeback_class, name, \
-	TP_PROTO(struct backing_dev_info *bdi), \
-	TP_ARGS(bdi))
+	TP_PROTO(struct bdi_writeback *wb), \
+	TP_ARGS(wb))
 
 DEFINE_WRITEBACK_EVENT(writeback_nowork);
 DEFINE_WRITEBACK_EVENT(writeback_wake_background);
-DEFINE_WRITEBACK_EVENT(writeback_bdi_register);
+
+TRACE_EVENT(writeback_bdi_register,
+	TP_PROTO(struct backing_dev_info *bdi),
+	TP_ARGS(bdi),
+	TP_STRUCT__entry(
+		__array(char, name, 32)
+	),
+	TP_fast_assign(
+		strncpy(__entry->name, dev_name(bdi->dev), 32);
+	),
+	TP_printk("bdi %s",
+		__entry->name
+	)
+);
 
 DECLARE_EVENT_CLASS(wbc_class,
 	TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi),
@@ -265,6 +347,7 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__field(int, range_cyclic)
 		__field(long, range_start)
 		__field(long, range_end)
+		__dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
 	),
 
 	TP_fast_assign(
@@ -278,11 +361,12 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__entry->range_cyclic	= wbc->range_cyclic;
 		__entry->range_start	= (long)wbc->range_start;
 		__entry->range_end	= (long)wbc->range_end;
+		__trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
 	),
 
 	TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
 		"bgrd=%d reclm=%d cyclic=%d "
-		"start=0x%lx end=0x%lx",
+		"start=0x%lx end=0x%lx cgroup=%s",
 		__entry->name,
 		__entry->nr_to_write,
 		__entry->pages_skipped,
@@ -292,7 +376,9 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__entry->for_reclaim,
 		__entry->range_cyclic,
 		__entry->range_start,
-		__entry->range_end)
+		__entry->range_end,
+		__get_str(cgroup)
+	)
 )
 
 #define DEFINE_WBC_EVENT(name) \
@@ -312,6 +398,7 @@ TRACE_EVENT(writeback_queue_io,
 		__field(long,		age)
 		__field(int,		moved)
 		__field(int,		reason)
+		__dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
 	),
 	TP_fast_assign(
 		unsigned long *older_than_this = work->older_than_this;
@@ -321,13 +408,15 @@ TRACE_EVENT(writeback_queue_io,
 				  (jiffies - *older_than_this) * 1000 / HZ : -1;
 		__entry->moved	= moved;
 		__entry->reason	= work->reason;
+		__trace_wb_assign_cgroup(__get_str(cgroup), wb);
 	),
-	TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s",
+	TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s cgroup=%s",
 		__entry->name,
 		__entry->older,	/* older_than_this in jiffies */
 		__entry->age,	/* older_than_this in relative milliseconds */
 		__entry->moved,
-		__print_symbolic(__entry->reason, WB_WORK_REASON)
+		__print_symbolic(__entry->reason, WB_WORK_REASON),
+		__get_str(cgroup)
 	)
 );
 
@@ -381,11 +470,11 @@ TRACE_EVENT(global_dirty_state,
 
 TRACE_EVENT(bdi_dirty_ratelimit,
 
-	TP_PROTO(struct backing_dev_info *bdi,
+	TP_PROTO(struct bdi_writeback *wb,
 		 unsigned long dirty_rate,
 		 unsigned long task_ratelimit),
 
-	TP_ARGS(bdi, dirty_rate, task_ratelimit),
+	TP_ARGS(wb, dirty_rate, task_ratelimit),
 
 	TP_STRUCT__entry(
 		__array(char,		bdi, 32)
@@ -395,36 +484,39 @@ TRACE_EVENT(bdi_dirty_ratelimit,
 		__field(unsigned long,	dirty_ratelimit)
 		__field(unsigned long,	task_ratelimit)
 		__field(unsigned long,	balanced_dirty_ratelimit)
+		__dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
 	),
 
 	TP_fast_assign(
-		strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
-		__entry->write_bw	= KBps(bdi->wb.write_bandwidth);
-		__entry->avg_write_bw	= KBps(bdi->wb.avg_write_bandwidth);
+		strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+		__entry->write_bw	= KBps(wb->write_bandwidth);
+		__entry->avg_write_bw	= KBps(wb->avg_write_bandwidth);
 		__entry->dirty_rate	= KBps(dirty_rate);
-		__entry->dirty_ratelimit = KBps(bdi->wb.dirty_ratelimit);
+		__entry->dirty_ratelimit = KBps(wb->dirty_ratelimit);
 		__entry->task_ratelimit	= KBps(task_ratelimit);
 		__entry->balanced_dirty_ratelimit =
-					KBps(bdi->wb.balanced_dirty_ratelimit);
+					KBps(wb->balanced_dirty_ratelimit);
+		__trace_wb_assign_cgroup(__get_str(cgroup), wb);
 	),
 
 	TP_printk("bdi %s: "
 		  "write_bw=%lu awrite_bw=%lu dirty_rate=%lu "
 		  "dirty_ratelimit=%lu task_ratelimit=%lu "
-		  "balanced_dirty_ratelimit=%lu",
+		  "balanced_dirty_ratelimit=%lu cgroup=%s",
 		  __entry->bdi,
 		  __entry->write_bw,		/* write bandwidth */
 		  __entry->avg_write_bw,	/* avg write bandwidth */
 		  __entry->dirty_rate,		/* bdi dirty rate */
 		  __entry->dirty_ratelimit,	/* base ratelimit */
 		  __entry->task_ratelimit, /* ratelimit with position control */
-		  __entry->balanced_dirty_ratelimit /* the balanced ratelimit */
+		  __entry->balanced_dirty_ratelimit, /* the balanced ratelimit */
+		  __get_str(cgroup)
 	)
 );
 
 TRACE_EVENT(balance_dirty_pages,
 
-	TP_PROTO(struct backing_dev_info *bdi,
+	TP_PROTO(struct bdi_writeback *wb,
 		 unsigned long thresh,
 		 unsigned long bg_thresh,
 		 unsigned long dirty,
@@ -437,7 +529,7 @@ TRACE_EVENT(balance_dirty_pages,
 		 long pause,
 		 unsigned long start_time),
 
-	TP_ARGS(bdi, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
+	TP_ARGS(wb, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
 		dirty_ratelimit, task_ratelimit,
 		dirtied, period, pause, start_time),
 
@@ -456,11 +548,12 @@ TRACE_EVENT(balance_dirty_pages,
 		__field(	 long,	pause)
 		__field(unsigned long,	period)
 		__field(	 long,	think)
+		__dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
 	),
 
 	TP_fast_assign(
 		unsigned long freerun = (thresh + bg_thresh) / 2;
-		strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
+		strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
 
 		__entry->limit		= global_wb_domain.dirty_limit;
 		__entry->setpoint	= (global_wb_domain.dirty_limit +
@@ -478,6 +571,7 @@ TRACE_EVENT(balance_dirty_pages,
 		__entry->period		= period * 1000 / HZ;
 		__entry->pause		= pause * 1000 / HZ;
 		__entry->paused		= (jiffies - start_time) * 1000 / HZ;
+		__trace_wb_assign_cgroup(__get_str(cgroup), wb);
 	),
 
 
@@ -486,7 +580,7 @@ TRACE_EVENT(balance_dirty_pages,
 		  "bdi_setpoint=%lu bdi_dirty=%lu "
 		  "dirty_ratelimit=%lu task_ratelimit=%lu "
 		  "dirtied=%u dirtied_pause=%u "
-		  "paused=%lu pause=%ld period=%lu think=%ld",
+		  "paused=%lu pause=%ld period=%lu think=%ld cgroup=%s",
 		  __entry->bdi,
 		  __entry->limit,
 		  __entry->setpoint,
@@ -500,7 +594,8 @@ TRACE_EVENT(balance_dirty_pages,
 		  __entry->paused,	/* ms */
 		  __entry->pause,	/* ms */
 		  __entry->period,	/* ms */
-		  __entry->think	/* ms */
+		  __entry->think,	/* ms */
+		  __get_str(cgroup)
 	  )
 );
 
@@ -514,6 +609,8 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
 		__field(unsigned long, ino)
 		__field(unsigned long, state)
 		__field(unsigned long, dirtied_when)
+		__dynamic_array(char, cgroup,
+				__trace_wb_cgroup_size(inode_to_wb(inode)))
 	),
 
 	TP_fast_assign(
@@ -522,14 +619,16 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
 		__entry->ino		= inode->i_ino;
 		__entry->state		= inode->i_state;
 		__entry->dirtied_when	= inode->dirtied_when;
+		__trace_wb_assign_cgroup(__get_str(cgroup), inode_to_wb(inode));
 	),
 
-	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu",
+	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu cgroup=%s",
 		  __entry->name,
 		  __entry->ino,
 		  show_inode_state(__entry->state),
 		  __entry->dirtied_when,
-		  (jiffies - __entry->dirtied_when) / HZ
+		  (jiffies - __entry->dirtied_when) / HZ,
+		  __get_str(cgroup)
 	)
 );
 
@@ -585,6 +684,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
 		__field(unsigned long, writeback_index)
 		__field(long, nr_to_write)
 		__field(unsigned long, wrote)
+		__dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
 	),
 
 	TP_fast_assign(
@@ -596,10 +696,11 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
 		__entry->writeback_index = inode->i_mapping->writeback_index;
 		__entry->nr_to_write	= nr_to_write;
 		__entry->wrote		= nr_to_write - wbc->nr_to_write;
+		__trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
 	),
 
 	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu "
-		  "index=%lu to_write=%ld wrote=%lu",
+		  "index=%lu to_write=%ld wrote=%lu cgroup=%s",
 		  __entry->name,
 		  __entry->ino,
 		  show_inode_state(__entry->state),
@@ -607,7 +708,8 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
 		  (jiffies - __entry->dirtied_when) / HZ,
 		  __entry->writeback_index,
 		  __entry->nr_to_write,
-		  __entry->wrote
+		  __entry->wrote,
+		  __get_str(cgroup)
 	)
 );
 

mm/backing-dev.c

@@ -523,7 +523,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
 	int ret = 0;
 
 	memcg = mem_cgroup_from_css(memcg_css);
-	blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &blkio_cgrp_subsys);
+	blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
 	blkcg = css_to_blkcg(blkcg_css);
 	memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
 	blkcg_cgwb_list = &blkcg->cgwb_list;
@@ -645,7 +645,7 @@ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
 
 			/* see whether the blkcg association has changed */
 			blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
-						     &blkio_cgrp_subsys);
+						     &io_cgrp_subsys);
 			if (unlikely(wb->blkcg_css != blkcg_css ||
 				     !wb_tryget(wb)))
 				wb = NULL;

mm/page-writeback.c

@@ -1289,7 +1289,7 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc,
 	wb->dirty_ratelimit = max(dirty_ratelimit, 1UL);
 	wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit;
 
-	trace_bdi_dirty_ratelimit(wb->bdi, dirty_rate, task_ratelimit);
+	trace_bdi_dirty_ratelimit(wb, dirty_rate, task_ratelimit);
 }
 
 static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc,
@@ -1683,7 +1683,7 @@ static void balance_dirty_pages(struct address_space *mapping,
 		 * do a reset, as it may be a light dirtier.
 		 */
 		if (pause < min_pause) {
-			trace_balance_dirty_pages(bdi,
+			trace_balance_dirty_pages(wb,
 						  sdtc->thresh,
 						  sdtc->bg_thresh,
 						  sdtc->dirty,
@@ -1712,7 +1712,7 @@ static void balance_dirty_pages(struct address_space *mapping,
 		}
 
 pause:
-		trace_balance_dirty_pages(bdi,
+		trace_balance_dirty_pages(wb,
 					  sdtc->thresh,
 					  sdtc->bg_thresh,
 					  sdtc->dirty,