4 files changed, 256 insertions, 116 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 0fe9df983ab7..5a5d79ee256f 100644
--- a/include/linux/backing-dev.h
+++ b/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 */
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index a4cd1641e9e2..0a5cc7a1109b 100644
--- a/include/linux/blk-cgroup.h
+++ b/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);
 }
 
 /**
@@ -233,6 +253,52 @@ static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 }
 
 /**
+ * __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
  * @pol: policy 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 @@ root_rl:
  */
 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)
 
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index 1f36945fd23d..1a96fdaa33d5 100644
--- a/include/linux/cgroup_subsys.h
+++ b/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)
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 123be25ea15a..5d4e9c4b821d 100644
--- a/include/linux/kernfs.h
+++ b/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; }