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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * cgroups support for the BFQ I/O scheduler.
  */
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>
 #include <linux/cgroup.h>
 #include <linux/ktime.h>
 #include <linux/rbtree.h>
 #include <linux/ioprio.h>
 #include <linux/sbitmap.h>
 #include <linux/delay.h>
 
 #include "elevator.h"
 #include "bfq-iosched.h"
 
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
 static int bfq_stat_init(struct bfq_stat *stat, gfp_t gfp)
 {
     int ret;
 
     ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
     if (ret)
         return ret;
 
     atomic64_set(&stat->aux_cnt, 0);
     return 0;
 }
 
 static void bfq_stat_exit(struct bfq_stat *stat)
 {
     percpu_counter_destroy(&stat->cpu_cnt);
 }
 
 /**
  * bfq_stat_add - add a value to a bfq_stat
  * @stat: target bfq_stat
  * @val: value to add
  *
  * 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 bfq_stat_add(struct bfq_stat *stat, uint64_t val)
 {
     percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
 }
 
 /**
  * bfq_stat_read - read the current value of a bfq_stat
  * @stat: bfq_stat to read
  */
 static inline uint64_t bfq_stat_read(struct bfq_stat *stat)
 {
     return percpu_counter_sum_positive(&stat->cpu_cnt);
 }
 
 /**
  * bfq_stat_reset - reset a bfq_stat
  * @stat: bfq_stat to reset
  */
 static inline void bfq_stat_reset(struct bfq_stat *stat)
 {
     percpu_counter_set(&stat->cpu_cnt, 0);
     atomic64_set(&stat->aux_cnt, 0);
 }
 
 /**
  * bfq_stat_add_aux - add a bfq_stat into another's aux count
  * @to: the destination bfq_stat
  * @from: the source
  *
  * Add @from's count including the aux one to @to's aux count.
  */
 static inline void bfq_stat_add_aux(struct bfq_stat *to,
                      struct bfq_stat *from)
 {
     atomic64_add(bfq_stat_read(from) + atomic64_read(&from->aux_cnt),
              &to->aux_cnt);
 }
 
 /**
  * blkg_prfill_stat - prfill callback for bfq_stat
  * @sf: seq_file to print to
  * @pd: policy private data of interest
  * @off: offset to the bfq_stat in @pd
  *
  * prfill callback for printing a bfq_stat.
  */
 static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
         int off)
 {
     return __blkg_prfill_u64(sf, pd, bfq_stat_read((void *)pd + off));
 }
 
 /* bfqg stats flags */
 enum bfqg_stats_flags {
     BFQG_stats_waiting = 0,
     BFQG_stats_idling,
     BFQG_stats_empty,
 };
 
 #define BFQG_FLAG_FNS(name)                     \
 static void bfqg_stats_mark_##name(struct bfqg_stats *stats)    \
 {                                   \
     stats->flags |= (1 << BFQG_stats_##name);           \
 }                                   \
 static void bfqg_stats_clear_##name(struct bfqg_stats *stats)   \
 {                                   \
     stats->flags &= ~(1 << BFQG_stats_##name);          \
 }                                   \
 static int bfqg_stats_##name(struct bfqg_stats *stats)      \
 {                                   \
     return (stats->flags & (1 << BFQG_stats_##name)) != 0;      \
 }                                   \
 
 BFQG_FLAG_FNS(waiting)
 BFQG_FLAG_FNS(idling)
 BFQG_FLAG_FNS(empty)
 #undef BFQG_FLAG_FNS
 
 /* This should be called with the scheduler lock held. */
 static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
 {
     u64 now;
 
     if (!bfqg_stats_waiting(stats))
         return;
 
     now = ktime_get_ns();
     if (now > stats->start_group_wait_time)
         bfq_stat_add(&stats->group_wait_time,
                   now - stats->start_group_wait_time);
     bfqg_stats_clear_waiting(stats);
 }
 
 /* This should be called with the scheduler lock held. */
 static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
                          struct bfq_group *curr_bfqg)
 {
     struct bfqg_stats *stats = &bfqg->stats;
 
     if (bfqg_stats_waiting(stats))
         return;
     if (bfqg == curr_bfqg)
         return;
     stats->start_group_wait_time = ktime_get_ns();
     bfqg_stats_mark_waiting(stats);
 }
 
 /* This should be called with the scheduler lock held. */
 static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
 {
     u64 now;
 
     if (!bfqg_stats_empty(stats))
         return;
 
     now = ktime_get_ns();
     if (now > stats->start_empty_time)
         bfq_stat_add(&stats->empty_time,
                   now - stats->start_empty_time);
     bfqg_stats_clear_empty(stats);
 }
 
 void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
 {
     bfq_stat_add(&bfqg->stats.dequeue, 1);
 }
 
 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
 {
     struct bfqg_stats *stats = &bfqg->stats;
 
     if (blkg_rwstat_total(&stats->queued))
         return;
 
     /*
      * group is already marked empty. This can happen if bfqq got new
      * request in parent group and moved to this group while being added
      * to service tree. Just ignore the event and move on.
      */
     if (bfqg_stats_empty(stats))
         return;
 
     stats->start_empty_time = ktime_get_ns();
     bfqg_stats_mark_empty(stats);
 }
 
 void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
 {
     struct bfqg_stats *stats = &bfqg->stats;
 
     if (bfqg_stats_idling(stats)) {
         u64 now = ktime_get_ns();
 
         if (now > stats->start_idle_time)
             bfq_stat_add(&stats->idle_time,
                       now - stats->start_idle_time);
         bfqg_stats_clear_idling(stats);
     }
 }
 
 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
 {
     struct bfqg_stats *stats = &bfqg->stats;
 
     stats->start_idle_time = ktime_get_ns();
     bfqg_stats_mark_idling(stats);
 }
 
 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
 {
     struct bfqg_stats *stats = &bfqg->stats;
 
     bfq_stat_add(&stats->avg_queue_size_sum,
               blkg_rwstat_total(&stats->queued));
     bfq_stat_add(&stats->avg_queue_size_samples, 1);
     bfqg_stats_update_group_wait_time(stats);
 }
 
 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
                   blk_opf_t opf)
 {
     blkg_rwstat_add(&bfqg->stats.queued, opf, 1);
     bfqg_stats_end_empty_time(&bfqg->stats);
     if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
         bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
 }
 
 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf)
 {
     blkg_rwstat_add(&bfqg->stats.queued, opf, -1);
 }
 
 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf)
 {
     blkg_rwstat_add(&bfqg->stats.merged, opf, 1);
 }
 
 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
                   u64 io_start_time_ns, blk_opf_t opf)
 {
     struct bfqg_stats *stats = &bfqg->stats;
     u64 now = ktime_get_ns();
 
     if (now > io_start_time_ns)
         blkg_rwstat_add(&stats->service_time, opf,
                 now - io_start_time_ns);
     if (io_start_time_ns > start_time_ns)
         blkg_rwstat_add(&stats->wait_time, opf,
                 io_start_time_ns - start_time_ns);
 }
 
 #else /* CONFIG_BFQ_CGROUP_DEBUG */
 
 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
                   blk_opf_t opf) { }
 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf) { }
 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf) { }
 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
                   u64 io_start_time_ns, blk_opf_t opf) { }
 void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
 void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
 
 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
 
 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 
 /*
  * blk-cgroup policy-related handlers
  * The following functions help in converting between blk-cgroup
  * internal structures and BFQ-specific structures.
  */
 
 static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
 {
     return pd ? container_of(pd, struct bfq_group, pd) : NULL;
 }
 
 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
 {
     return pd_to_blkg(&bfqg->pd);
 }
 
 static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
 {
     return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq));
 }
 
 /*
  * bfq_group handlers
  * The following functions help in navigating the bfq_group hierarchy
  * by allowing to find the parent of a bfq_group or the bfq_group
  * associated to a bfq_queue.
  */
 
 static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
 {
     struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
 
     return pblkg ? blkg_to_bfqg(pblkg) : NULL;
 }
 
 struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
 {
     struct bfq_entity *group_entity = bfqq->entity.parent;
 
     return group_entity ? container_of(group_entity, struct bfq_group,
                        entity) :
                   bfqq->bfqd->root_group;
 }
 
 /*
  * The following two functions handle get and put of a bfq_group by
  * wrapping the related blk-cgroup hooks.
  */
 
 static void bfqg_get(struct bfq_group *bfqg)
 {
     bfqg->ref++;
 }
 
 static void bfqg_put(struct bfq_group *bfqg)
 {
     bfqg->ref--;
 
     if (bfqg->ref == 0)
         kfree(bfqg);
 }
 
 static void bfqg_and_blkg_get(struct bfq_group *bfqg)
 {
     /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
     bfqg_get(bfqg);
 
     blkg_get(bfqg_to_blkg(bfqg));
 }
 
 void bfqg_and_blkg_put(struct bfq_group *bfqg)
 {
     blkg_put(bfqg_to_blkg(bfqg));
 
     bfqg_put(bfqg);
 }
 
 void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq)
 {
     struct bfq_group *bfqg = blkg_to_bfqg(rq->bio->bi_blkg);
 
     if (!bfqg)
         return;
 
     blkg_rwstat_add(&bfqg->stats.bytes, rq->cmd_flags, blk_rq_bytes(rq));
     blkg_rwstat_add(&bfqg->stats.ios, rq->cmd_flags, 1);
 }
 
 /* @stats = 0 */
 static void bfqg_stats_reset(struct bfqg_stats *stats)
 {
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
     /* queued stats shouldn't be cleared */
     blkg_rwstat_reset(&stats->merged);
     blkg_rwstat_reset(&stats->service_time);
     blkg_rwstat_reset(&stats->wait_time);
     bfq_stat_reset(&stats->time);
     bfq_stat_reset(&stats->avg_queue_size_sum);
     bfq_stat_reset(&stats->avg_queue_size_samples);
     bfq_stat_reset(&stats->dequeue);
     bfq_stat_reset(&stats->group_wait_time);
     bfq_stat_reset(&stats->idle_time);
     bfq_stat_reset(&stats->empty_time);
 #endif
 }
 
 /* @to += @from */
 static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
 {
     if (!to || !from)
         return;
 
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
     /* queued stats shouldn't be cleared */
     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);
     bfq_stat_add_aux(&from->time, &from->time);
     bfq_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
     bfq_stat_add_aux(&to->avg_queue_size_samples,
               &from->avg_queue_size_samples);
     bfq_stat_add_aux(&to->dequeue, &from->dequeue);
     bfq_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
     bfq_stat_add_aux(&to->idle_time, &from->idle_time);
     bfq_stat_add_aux(&to->empty_time, &from->empty_time);
 #endif
 }
 
 /*
  * Transfer @bfqg's stats to its parent's aux counts so that the ancestors'
  * recursive stats can still account for the amount used by this bfqg after
  * it's gone.
  */
 static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
 {
     struct bfq_group *parent;
 
     if (!bfqg) /* root_group */
         return;
 
     parent = bfqg_parent(bfqg);
 
     lockdep_assert_held(&bfqg_to_blkg(bfqg)->q->queue_lock);
 
     if (unlikely(!parent))
         return;
 
     bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
     bfqg_stats_reset(&bfqg->stats);
 }
 
 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
 {
     struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
 
     entity->weight = entity->new_weight;
     entity->orig_weight = entity->new_weight;
     if (bfqq) {
         bfqq->ioprio = bfqq->new_ioprio;
         bfqq->ioprio_class = bfqq->new_ioprio_class;
         /*
          * Make sure that bfqg and its associated blkg do not
          * disappear before entity.
          */
         bfqg_and_blkg_get(bfqg);
     }
     entity->parent = bfqg->my_entity; /* NULL for root group */
     entity->sched_data = &bfqg->sched_data;
 }
 
 static void bfqg_stats_exit(struct bfqg_stats *stats)
 {
     blkg_rwstat_exit(&stats->bytes);
     blkg_rwstat_exit(&stats->ios);
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
     blkg_rwstat_exit(&stats->merged);
     blkg_rwstat_exit(&stats->service_time);
     blkg_rwstat_exit(&stats->wait_time);
     blkg_rwstat_exit(&stats->queued);
     bfq_stat_exit(&stats->time);
     bfq_stat_exit(&stats->avg_queue_size_sum);
     bfq_stat_exit(&stats->avg_queue_size_samples);
     bfq_stat_exit(&stats->dequeue);
     bfq_stat_exit(&stats->group_wait_time);
     bfq_stat_exit(&stats->idle_time);
     bfq_stat_exit(&stats->empty_time);
 #endif
 }
 
 static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
 {
     if (blkg_rwstat_init(&stats->bytes, gfp) ||
         blkg_rwstat_init(&stats->ios, gfp))
         goto error;
 
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
     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) ||
         bfq_stat_init(&stats->time, gfp) ||
         bfq_stat_init(&stats->avg_queue_size_sum, gfp) ||
         bfq_stat_init(&stats->avg_queue_size_samples, gfp) ||
         bfq_stat_init(&stats->dequeue, gfp) ||
         bfq_stat_init(&stats->group_wait_time, gfp) ||
         bfq_stat_init(&stats->idle_time, gfp) ||
         bfq_stat_init(&stats->empty_time, gfp))
         goto error;
 #endif
 
     return 0;
 
 error:
     bfqg_stats_exit(stats);
     return -ENOMEM;
 }
 
 static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
 {
     return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
 }
 
 static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
 {
     return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
 }
 
 static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
 {
     struct bfq_group_data *bgd;
 
     bgd = kzalloc(sizeof(*bgd), gfp);
     if (!bgd)
         return NULL;
     return &bgd->pd;
 }
 
 static void bfq_cpd_init(struct blkcg_policy_data *cpd)
 {
     struct bfq_group_data *d = cpd_to_bfqgd(cpd);
 
     d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
         CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
 }
 
 static void bfq_cpd_free(struct blkcg_policy_data *cpd)
 {
     kfree(cpd_to_bfqgd(cpd));
 }
 
 static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, struct request_queue *q,
                          struct blkcg *blkcg)
 {
     struct bfq_group *bfqg;
 
     bfqg = kzalloc_node(sizeof(*bfqg), gfp, q->node);
     if (!bfqg)
         return NULL;
 
     if (bfqg_stats_init(&bfqg->stats, gfp)) {
         kfree(bfqg);
         return NULL;
     }
 
     /* see comments in bfq_bic_update_cgroup for why refcounting */
     bfqg_get(bfqg);
     return &bfqg->pd;
 }
 
 static void bfq_pd_init(struct blkg_policy_data *pd)
 {
     struct blkcg_gq *blkg = pd_to_blkg(pd);
     struct bfq_group *bfqg = blkg_to_bfqg(blkg);
     struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
     struct bfq_entity *entity = &bfqg->entity;
     struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
 
     entity->orig_weight = entity->weight = entity->new_weight = d->weight;
     entity->my_sched_data = &bfqg->sched_data;
     entity->last_bfqq_created = NULL;
 
     bfqg->my_entity = entity; /*
                    * the root_group's will be set to NULL
                    * in bfq_init_queue()
                    */
     bfqg->bfqd = bfqd;
     bfqg->active_entities = 0;
     bfqg->online = true;
     bfqg->rq_pos_tree = RB_ROOT;
 }
 
 static void bfq_pd_free(struct blkg_policy_data *pd)
 {
     struct bfq_group *bfqg = pd_to_bfqg(pd);
 
     bfqg_stats_exit(&bfqg->stats);
     bfqg_put(bfqg);
 }
 
 static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
 {
     struct bfq_group *bfqg = pd_to_bfqg(pd);
 
     bfqg_stats_reset(&bfqg->stats);
 }
 
 static void bfq_group_set_parent(struct bfq_group *bfqg,
                     struct bfq_group *parent)
 {
     struct bfq_entity *entity;
 
     entity = &bfqg->entity;
     entity->parent = parent->my_entity;
     entity->sched_data = &parent->sched_data;
 }
 
 static void bfq_link_bfqg(struct bfq_data *bfqd, struct bfq_group *bfqg)
 {
     struct bfq_group *parent;
     struct bfq_entity *entity;
 
     /*
      * Update chain of bfq_groups as we might be handling a leaf group
      * which, along with some of its relatives, has not been hooked yet
      * to the private hierarchy of BFQ.
      */
     entity = &bfqg->entity;
     for_each_entity(entity) {
         struct bfq_group *curr_bfqg = container_of(entity,
                         struct bfq_group, entity);
         if (curr_bfqg != bfqd->root_group) {
             parent = bfqg_parent(curr_bfqg);
             if (!parent)
                 parent = bfqd->root_group;
             bfq_group_set_parent(curr_bfqg, parent);
         }
     }
 }
 
 struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
 {
     struct blkcg_gq *blkg = bio->bi_blkg;
     struct bfq_group *bfqg;
 
     while (blkg) {
         bfqg = blkg_to_bfqg(blkg);
         if (bfqg->online) {
             bio_associate_blkg_from_css(bio, &blkg->blkcg->css);
             return bfqg;
         }
         blkg = blkg->parent;
     }
     bio_associate_blkg_from_css(bio,
                 &bfqg_to_blkg(bfqd->root_group)->blkcg->css);
     return bfqd->root_group;
 }
 
 /**
  * bfq_bfqq_move - migrate @bfqq to @bfqg.
  * @bfqd: queue descriptor.
  * @bfqq: the queue to move.
  * @bfqg: the group to move to.
  *
  * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
  * it on the new one.  Avoid putting the entity on the old group idle tree.
  *
  * Must be called under the scheduler lock, to make sure that the blkg
  * owning @bfqg does not disappear (see comments in
  * bfq_bic_update_cgroup on guaranteeing the consistency of blkg
  * objects).
  */
 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
            struct bfq_group *bfqg)
 {
     struct bfq_entity *entity = &bfqq->entity;
     struct bfq_group *old_parent = bfqq_group(bfqq);
 
     /*
      * No point to move bfqq to the same group, which can happen when
      * root group is offlined
      */
     if (old_parent == bfqg)
         return;
 
     /*
      * oom_bfqq is not allowed to move, oom_bfqq will hold ref to root_group
      * until elevator exit.
      */
     if (bfqq == &bfqd->oom_bfqq)
         return;
     /*
      * Get extra reference to prevent bfqq from being freed in
      * next possible expire or deactivate.
      */
     bfqq->ref++;
 
     /* If bfqq is empty, then bfq_bfqq_expire also invokes
      * bfq_del_bfqq_busy, thereby removing bfqq and its entity
      * from data structures related to current group. Otherwise we
      * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
      * we do below.
      */
     if (bfqq == bfqd->in_service_queue)
         bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
                 false, BFQQE_PREEMPTED);
 
     if (bfq_bfqq_busy(bfqq))
         bfq_deactivate_bfqq(bfqd, bfqq, false, false);
     else if (entity->on_st_or_in_serv)
         bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
     bfqg_and_blkg_put(old_parent);
 
     if (entity->parent &&
         entity->parent->last_bfqq_created == bfqq)
         entity->parent->last_bfqq_created = NULL;
     else if (bfqd->last_bfqq_created == bfqq)
         bfqd->last_bfqq_created = NULL;
 
     entity->parent = bfqg->my_entity;
     entity->sched_data = &bfqg->sched_data;
     /* pin down bfqg and its associated blkg  */
     bfqg_and_blkg_get(bfqg);
 
     if (bfq_bfqq_busy(bfqq)) {
         if (unlikely(!bfqd->nonrot_with_queueing))
             bfq_pos_tree_add_move(bfqd, bfqq);
         bfq_activate_bfqq(bfqd, bfqq);
     }
 
     if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
         bfq_schedule_dispatch(bfqd);
     /* release extra ref taken above, bfqq may happen to be freed now */
     bfq_put_queue(bfqq);
 }
 
 /**
  * __bfq_bic_change_cgroup - move @bic to @bfqg.
  * @bfqd: the queue descriptor.
  * @bic: the bic to move.
  * @bfqg: the group to move to.
  *
  * Move bic to blkcg, assuming that bfqd->lock is held; which makes
  * sure that the reference to cgroup is valid across the call (see
  * comments in bfq_bic_update_cgroup on this issue)
  */
 static void *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
                      struct bfq_io_cq *bic,
                      struct bfq_group *bfqg)
 {
     struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
     struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
     struct bfq_entity *entity;
 
     if (async_bfqq) {
         entity = &async_bfqq->entity;
 
         if (entity->sched_data != &bfqg->sched_data) {
             bic_set_bfqq(bic, NULL, 0);
             bfq_release_process_ref(bfqd, async_bfqq);
         }
     }
 
     if (sync_bfqq) {
         if (!sync_bfqq->new_bfqq && !bfq_bfqq_coop(sync_bfqq)) {
             /* We are the only user of this bfqq, just move it */
             if (sync_bfqq->entity.sched_data != &bfqg->sched_data)
                 bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
         } else {
             struct bfq_queue *bfqq;
 
             /*
              * The queue was merged to a different queue. Check
              * that the merge chain still belongs to the same
              * cgroup.
              */
             for (bfqq = sync_bfqq; bfqq; bfqq = bfqq->new_bfqq)
                 if (bfqq->entity.sched_data !=
                     &bfqg->sched_data)
                     break;
             if (bfqq) {
                 /*
                  * Some queue changed cgroup so the merge is
                  * not valid anymore. We cannot easily just
                  * cancel the merge (by clearing new_bfqq) as
                  * there may be other processes using this
                  * queue and holding refs to all queues below
                  * sync_bfqq->new_bfqq. Similarly if the merge
                  * already happened, we need to detach from
                  * bfqq now so that we cannot merge bio to a
                  * request from the old cgroup.
                  */
                 bfq_put_cooperator(sync_bfqq);
                 bfq_release_process_ref(bfqd, sync_bfqq);
                 bic_set_bfqq(bic, NULL, 1);
             }
         }
     }
 
     return bfqg;
 }
 
 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
 {
     struct bfq_data *bfqd = bic_to_bfqd(bic);
     struct bfq_group *bfqg = bfq_bio_bfqg(bfqd, bio);
     uint64_t serial_nr;
 
     serial_nr = bfqg_to_blkg(bfqg)->blkcg->css.serial_nr;
 
     /*
      * Check whether blkcg has changed.  The condition may trigger
      * spuriously on a newly created cic but there's no harm.
      */
     if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
         return;
 
     /*
      * New cgroup for this process. Make sure it is linked to bfq internal
      * cgroup hierarchy.
      */
     bfq_link_bfqg(bfqd, bfqg);
     __bfq_bic_change_cgroup(bfqd, bic, bfqg);
     /*
      * Update blkg_path for bfq_log_* functions. We cache this
      * path, and update it here, for the following
      * reasons. Operations on blkg objects in blk-cgroup are
      * protected with the request_queue lock, and not with the
      * lock that protects the instances of this scheduler
      * (bfqd->lock). This exposes BFQ to the following sort of
      * race.
      *
      * The blkg_lookup performed in bfq_get_queue, protected
      * through rcu, may happen to return the address of a copy of
      * the original blkg. If this is the case, then the
      * bfqg_and_blkg_get performed in bfq_get_queue, to pin down
      * the blkg, is useless: it does not prevent blk-cgroup code
      * from destroying both the original blkg and all objects
      * directly or indirectly referred by the copy of the
      * blkg.
      *
      * On the bright side, destroy operations on a blkg invoke, as
      * a first step, hooks of the scheduler associated with the
      * blkg. And these hooks are executed with bfqd->lock held for
      * BFQ. As a consequence, for any blkg associated with the
      * request queue this instance of the scheduler is attached
      * to, we are guaranteed that such a blkg is not destroyed, and
      * that all the pointers it contains are consistent, while we
      * are holding bfqd->lock. A blkg_lookup performed with
      * bfqd->lock held then returns a fully consistent blkg, which
      * remains consistent until this lock is held.
      *
      * Thanks to the last fact, and to the fact that: (1) bfqg has
      * been obtained through a blkg_lookup in the above
      * assignment, and (2) bfqd->lock is being held, here we can
      * safely use the policy data for the involved blkg (i.e., the
      * field bfqg->pd) to get to the blkg associated with bfqg,
      * and then we can safely use any field of blkg. After we
      * release bfqd->lock, even just getting blkg through this
      * bfqg may cause dangling references to be traversed, as
      * bfqg->pd may not exist any more.
      *
      * In view of the above facts, here we cache, in the bfqg, any
      * blkg data we may need for this bic, and for its associated
      * bfq_queue. As of now, we need to cache only the path of the
      * blkg, which is used in the bfq_log_* functions.
      *
      * Finally, note that bfqg itself needs to be protected from
      * destruction on the blkg_free of the original blkg (which
      * invokes bfq_pd_free). We use an additional private
      * refcounter for bfqg, to let it disappear only after no
      * bfq_queue refers to it any longer.
      */
     blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path));
     bic->blkcg_serial_nr = serial_nr;
 }
 
 /**
  * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
  * @st: the service tree being flushed.
  */
 static void bfq_flush_idle_tree(struct bfq_service_tree *st)
 {
     struct bfq_entity *entity = st->first_idle;
 
     for (; entity ; entity = st->first_idle)
         __bfq_deactivate_entity(entity, false);
 }
 
 /**
  * bfq_reparent_leaf_entity - move leaf entity to the root_group.
  * @bfqd: the device data structure with the root group.
  * @entity: the entity to move, if entity is a leaf; or the parent entity
  *      of an active leaf entity to move, if entity is not a leaf.
  * @ioprio_class: I/O priority class to reparent.
  */
 static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
                      struct bfq_entity *entity,
                      int ioprio_class)
 {
     struct bfq_queue *bfqq;
     struct bfq_entity *child_entity = entity;
 
     while (child_entity->my_sched_data) { /* leaf not reached yet */
         struct bfq_sched_data *child_sd = child_entity->my_sched_data;
         struct bfq_service_tree *child_st = child_sd->service_tree +
             ioprio_class;
         struct rb_root *child_active = &child_st->active;
 
         child_entity = bfq_entity_of(rb_first(child_active));
 
         if (!child_entity)
             child_entity = child_sd->in_service_entity;
     }
 
     bfqq = bfq_entity_to_bfqq(child_entity);
     bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
 }
 
 /**
  * bfq_reparent_active_queues - move to the root group all active queues.
  * @bfqd: the device data structure with the root group.
  * @bfqg: the group to move from.
  * @st: the service tree to start the search from.
  * @ioprio_class: I/O priority class to reparent.
  */
 static void bfq_reparent_active_queues(struct bfq_data *bfqd,
                        struct bfq_group *bfqg,
                        struct bfq_service_tree *st,
                        int ioprio_class)
 {
     struct rb_root *active = &st->active;
     struct bfq_entity *entity;
 
     while ((entity = bfq_entity_of(rb_first(active))))
         bfq_reparent_leaf_entity(bfqd, entity, ioprio_class);
 
     if (bfqg->sched_data.in_service_entity)
         bfq_reparent_leaf_entity(bfqd,
                      bfqg->sched_data.in_service_entity,
                      ioprio_class);
 }
 
 /**
  * bfq_pd_offline - deactivate the entity associated with @pd,
  *          and reparent its children entities.
  * @pd: descriptor of the policy going offline.
  *
  * blkio already grabs the queue_lock for us, so no need to use
  * RCU-based magic
  */
 static void bfq_pd_offline(struct blkg_policy_data *pd)
 {
     struct bfq_service_tree *st;
     struct bfq_group *bfqg = pd_to_bfqg(pd);
     struct bfq_data *bfqd = bfqg->bfqd;
     struct bfq_entity *entity = bfqg->my_entity;
     unsigned long flags;
     int i;
 
     spin_lock_irqsave(&bfqd->lock, flags);
 
     if (!entity) /* root group */
         goto put_async_queues;
 
     /*
      * Empty all service_trees belonging to this group before
      * deactivating the group itself.
      */
     for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
         st = bfqg->sched_data.service_tree + i;
 
         /*
          * It may happen that some queues are still active
          * (busy) upon group destruction (if the corresponding
          * processes have been forced to terminate). We move
          * all the leaf entities corresponding to these queues
          * to the root_group.
          * Also, it may happen that the group has an entity
          * in service, which is disconnected from the active
          * tree: it must be moved, too.
          * There is no need to put the sync queues, as the
          * scheduler has taken no reference.
          */
         bfq_reparent_active_queues(bfqd, bfqg, st, i);
 
         /*
          * The idle tree may still contain bfq_queues
          * belonging to exited task because they never
          * migrated to a different cgroup from the one being
          * destroyed now. In addition, even
          * bfq_reparent_active_queues() may happen to add some
          * entities to the idle tree. It happens if, in some
          * of the calls to bfq_bfqq_move() performed by
          * bfq_reparent_active_queues(), the queue to move is
          * empty and gets expired.
          */
         bfq_flush_idle_tree(st);
     }
 
     __bfq_deactivate_entity(entity, false);
 
 put_async_queues:
     bfq_put_async_queues(bfqd, bfqg);
     bfqg->online = false;
 
     spin_unlock_irqrestore(&bfqd->lock, flags);
     /*
      * @blkg is going offline and will be ignored by
      * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
      * that they don't get lost.  If IOs complete after this point, the
      * stats for them will be lost.  Oh well...
      */
     bfqg_stats_xfer_dead(bfqg);
 }
 
 void bfq_end_wr_async(struct bfq_data *bfqd)
 {
     struct blkcg_gq *blkg;
 
     list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
         struct bfq_group *bfqg = blkg_to_bfqg(blkg);
 
         bfq_end_wr_async_queues(bfqd, bfqg);
     }
     bfq_end_wr_async_queues(bfqd, bfqd->root_group);
 }
 
 static int bfq_io_show_weight_legacy(struct seq_file *sf, void *v)
 {
     struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
     struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
     unsigned int val = 0;
 
     if (bfqgd)
         val = bfqgd->weight;
 
     seq_printf(sf, "%u\n", val);
 
     return 0;
 }
 
 static u64 bfqg_prfill_weight_device(struct seq_file *sf,
                      struct blkg_policy_data *pd, int off)
 {
     struct bfq_group *bfqg = pd_to_bfqg(pd);
 
     if (!bfqg->entity.dev_weight)
         return 0;
     return __blkg_prfill_u64(sf, pd, bfqg->entity.dev_weight);
 }
 
 static int bfq_io_show_weight(struct seq_file *sf, void *v)
 {
     struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
     struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
 
     seq_printf(sf, "default %u\n", bfqgd->weight);
     blkcg_print_blkgs(sf, blkcg, bfqg_prfill_weight_device,
               &blkcg_policy_bfq, 0, false);
     return 0;
 }
 
 static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight, u64 dev_weight)
 {
     weight = dev_weight ?: weight;
 
     bfqg->entity.dev_weight = dev_weight;
     /*
      * Setting the prio_changed flag of the entity
      * to 1 with new_weight == weight would re-set
      * the value of the weight to its ioprio mapping.
      * Set the flag only if necessary.
      */
     if ((unsigned short)weight != bfqg->entity.new_weight) {
         bfqg->entity.new_weight = (unsigned short)weight;
         /*
          * Make sure that the above new value has been
          * stored in bfqg->entity.new_weight before
          * setting the prio_changed flag. In fact,
          * this flag may be read asynchronously (in
          * critical sections protected by a different
          * lock than that held here), and finding this
          * flag set may cause the execution of the code
          * for updating parameters whose value may
          * depend also on bfqg->entity.new_weight (in
          * __bfq_entity_update_weight_prio).
          * This barrier makes sure that the new value
          * of bfqg->entity.new_weight is correctly
          * seen in that code.
          */
         smp_wmb();
         bfqg->entity.prio_changed = 1;
     }
 }
 
 static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
                     struct cftype *cftype,
                     u64 val)
 {
     struct blkcg *blkcg = css_to_blkcg(css);
     struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
     struct blkcg_gq *blkg;
     int ret = -ERANGE;
 
     if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
         return ret;
 
     ret = 0;
     spin_lock_irq(&blkcg->lock);
     bfqgd->weight = (unsigned short)val;
     hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
         struct bfq_group *bfqg = blkg_to_bfqg(blkg);
 
         if (bfqg)
             bfq_group_set_weight(bfqg, val, 0);
     }
     spin_unlock_irq(&blkcg->lock);
 
     return ret;
 }
 
 static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
                     char *buf, size_t nbytes,
                     loff_t off)
 {
     int ret;
     struct blkg_conf_ctx ctx;
     struct blkcg *blkcg = css_to_blkcg(of_css(of));
     struct bfq_group *bfqg;
     u64 v;
 
     ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, buf, &ctx);
     if (ret)
         return ret;
 
     if (sscanf(ctx.body, "%llu", &v) == 1) {
         /* require "default" on dfl */
         ret = -ERANGE;
         if (!v)
             goto out;
     } else if (!strcmp(strim(ctx.body), "default")) {
         v = 0;
     } else {
         ret = -EINVAL;
         goto out;
     }
 
     bfqg = blkg_to_bfqg(ctx.blkg);
 
     ret = -ERANGE;
     if (!v || (v >= BFQ_MIN_WEIGHT && v <= BFQ_MAX_WEIGHT)) {
         bfq_group_set_weight(bfqg, bfqg->entity.weight, v);
         ret = 0;
     }
 out:
     blkg_conf_finish(&ctx);
     return ret ?: nbytes;
 }
 
 static ssize_t bfq_io_set_weight(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 = bfq_io_set_weight_legacy(of_css(of), NULL, v);
         return ret ?: nbytes;
     }
 
     return bfq_io_set_device_weight(of, buf, nbytes, off);
 }
 
 static int bfqg_print_rwstat(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
               &blkcg_policy_bfq, seq_cft(sf)->private, true);
     return 0;
 }
 
 static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
                     struct blkg_policy_data *pd, int off)
 {
     struct blkg_rwstat_sample sum;
 
     blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum);
     return __blkg_prfill_rwstat(sf, pd, &sum);
 }
 
 static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
               bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
               seq_cft(sf)->private, true);
     return 0;
 }
 
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
 static int bfqg_print_stat(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
               &blkcg_policy_bfq, seq_cft(sf)->private, false);
     return 0;
 }
 
 static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
                       struct blkg_policy_data *pd, int off)
 {
     struct blkcg_gq *blkg = pd_to_blkg(pd);
     struct blkcg_gq *pos_blkg;
     struct cgroup_subsys_state *pos_css;
     u64 sum = 0;
 
     lockdep_assert_held(&blkg->q->queue_lock);
 
     rcu_read_lock();
     blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
         struct bfq_stat *stat;
 
         if (!pos_blkg->online)
             continue;
 
         stat = (void *)blkg_to_pd(pos_blkg, &blkcg_policy_bfq) + off;
         sum += bfq_stat_read(stat) + atomic64_read(&stat->aux_cnt);
     }
     rcu_read_unlock();
 
     return __blkg_prfill_u64(sf, pd, sum);
 }
 
 static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
               bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
               seq_cft(sf)->private, false);
     return 0;
 }
 
 static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
                    int off)
 {
     struct bfq_group *bfqg = blkg_to_bfqg(pd->blkg);
     u64 sum = blkg_rwstat_total(&bfqg->stats.bytes);
 
     return __blkg_prfill_u64(sf, pd, sum >> 9);
 }
 
 static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
               bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
     return 0;
 }
 
 static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
                      struct blkg_policy_data *pd, int off)
 {
     struct blkg_rwstat_sample tmp;
 
     blkg_rwstat_recursive_sum(pd->blkg, &blkcg_policy_bfq,
             offsetof(struct bfq_group, stats.bytes), &tmp);
 
     return __blkg_prfill_u64(sf, pd,
         (tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]) >> 9);
 }
 
 static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
               bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
               false);
     return 0;
 }
 
 static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
                       struct blkg_policy_data *pd, int off)
 {
     struct bfq_group *bfqg = pd_to_bfqg(pd);
     u64 samples = bfq_stat_read(&bfqg->stats.avg_queue_size_samples);
     u64 v = 0;
 
     if (samples) {
         v = bfq_stat_read(&bfqg->stats.avg_queue_size_sum);
         v = div64_u64(v, samples);
     }
     __blkg_prfill_u64(sf, pd, v);
     return 0;
 }
 
 /* print avg_queue_size */
 static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
 {
     blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
               bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
               0, false);
     return 0;
 }
 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
 
 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
 {
     int ret;
 
     ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
     if (ret)
         return NULL;
 
     return blkg_to_bfqg(bfqd->queue->root_blkg);
 }
 
 struct blkcg_policy blkcg_policy_bfq = {
     .dfl_cftypes        = bfq_blkg_files,
     .legacy_cftypes     = bfq_blkcg_legacy_files,
 
     .cpd_alloc_fn       = bfq_cpd_alloc,
     .cpd_init_fn        = bfq_cpd_init,
     .cpd_bind_fn            = bfq_cpd_init,
     .cpd_free_fn        = bfq_cpd_free,
 
     .pd_alloc_fn        = bfq_pd_alloc,
     .pd_init_fn     = bfq_pd_init,
     .pd_offline_fn      = bfq_pd_offline,
     .pd_free_fn     = bfq_pd_free,
     .pd_reset_stats_fn  = bfq_pd_reset_stats,
 };
 
 struct cftype bfq_blkcg_legacy_files[] = {
     {
         .name = "bfq.weight",
         .flags = CFTYPE_NOT_ON_ROOT,
         .seq_show = bfq_io_show_weight_legacy,
         .write_u64 = bfq_io_set_weight_legacy,
     },
     {
         .name = "bfq.weight_device",
         .flags = CFTYPE_NOT_ON_ROOT,
         .seq_show = bfq_io_show_weight,
         .write = bfq_io_set_weight,
     },
 
     /* statistics, covers only the tasks in the bfqg */
     {
         .name = "bfq.io_service_bytes",
         .private = offsetof(struct bfq_group, stats.bytes),
         .seq_show = bfqg_print_rwstat,
     },
     {
         .name = "bfq.io_serviced",
         .private = offsetof(struct bfq_group, stats.ios),
         .seq_show = bfqg_print_rwstat,
     },
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
     {
         .name = "bfq.time",
         .private = offsetof(struct bfq_group, stats.time),
         .seq_show = bfqg_print_stat,
     },
     {
         .name = "bfq.sectors",
         .seq_show = bfqg_print_stat_sectors,
     },
     {
         .name = "bfq.io_service_time",
         .private = offsetof(struct bfq_group, stats.service_time),
         .seq_show = bfqg_print_rwstat,
     },
     {
         .name = "bfq.io_wait_time",
         .private = offsetof(struct bfq_group, stats.wait_time),
         .seq_show = bfqg_print_rwstat,
     },
     {
         .name = "bfq.io_merged",
         .private = offsetof(struct bfq_group, stats.merged),
         .seq_show = bfqg_print_rwstat,
     },
     {
         .name = "bfq.io_queued",
         .private = offsetof(struct bfq_group, stats.queued),
         .seq_show = bfqg_print_rwstat,
     },
 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
 
     /* the same statistics which cover the bfqg and its descendants */
     {
         .name = "bfq.io_service_bytes_recursive",
         .private = offsetof(struct bfq_group, stats.bytes),
         .seq_show = bfqg_print_rwstat_recursive,
     },
     {
         .name = "bfq.io_serviced_recursive",
         .private = offsetof(struct bfq_group, stats.ios),
         .seq_show = bfqg_print_rwstat_recursive,
     },
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
     {
         .name = "bfq.time_recursive",
         .private = offsetof(struct bfq_group, stats.time),
         .seq_show = bfqg_print_stat_recursive,
     },
     {
         .name = "bfq.sectors_recursive",
         .seq_show = bfqg_print_stat_sectors_recursive,
     },
     {
         .name = "bfq.io_service_time_recursive",
         .private = offsetof(struct bfq_group, stats.service_time),
         .seq_show = bfqg_print_rwstat_recursive,
     },
     {
         .name = "bfq.io_wait_time_recursive",
         .private = offsetof(struct bfq_group, stats.wait_time),
         .seq_show = bfqg_print_rwstat_recursive,
     },
     {
         .name = "bfq.io_merged_recursive",
         .private = offsetof(struct bfq_group, stats.merged),
         .seq_show = bfqg_print_rwstat_recursive,
     },
     {
         .name = "bfq.io_queued_recursive",
         .private = offsetof(struct bfq_group, stats.queued),
         .seq_show = bfqg_print_rwstat_recursive,
     },
     {
         .name = "bfq.avg_queue_size",
         .seq_show = bfqg_print_avg_queue_size,
     },
     {
         .name = "bfq.group_wait_time",
         .private = offsetof(struct bfq_group, stats.group_wait_time),
         .seq_show = bfqg_print_stat,
     },
     {
         .name = "bfq.idle_time",
         .private = offsetof(struct bfq_group, stats.idle_time),
         .seq_show = bfqg_print_stat,
     },
     {
         .name = "bfq.empty_time",
         .private = offsetof(struct bfq_group, stats.empty_time),
         .seq_show = bfqg_print_stat,
     },
     {
         .name = "bfq.dequeue",
         .private = offsetof(struct bfq_group, stats.dequeue),
         .seq_show = bfqg_print_stat,
     },
 #endif  /* CONFIG_BFQ_CGROUP_DEBUG */
     { } /* terminate */
 };
 
 struct cftype bfq_blkg_files[] = {
     {
         .name = "bfq.weight",
         .flags = CFTYPE_NOT_ON_ROOT,
         .seq_show = bfq_io_show_weight,
         .write = bfq_io_set_weight,
     },
     {} /* terminate */
 };
 
 #else   /* CONFIG_BFQ_GROUP_IOSCHED */
 
 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
            struct bfq_group *bfqg) {}
 
 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
 {
     struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
 
     entity->weight = entity->new_weight;
     entity->orig_weight = entity->new_weight;
     if (bfqq) {
         bfqq->ioprio = bfqq->new_ioprio;
         bfqq->ioprio_class = bfqq->new_ioprio_class;
     }
     entity->sched_data = &bfqg->sched_data;
 }
 
 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
 
 void bfq_end_wr_async(struct bfq_data *bfqd)
 {
     bfq_end_wr_async_queues(bfqd, bfqd->root_group);
 }
 
 struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
 {
     return bfqd->root_group;
 }
 
 struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
 {
     return bfqq->bfqd->root_group;
 }
 
 void bfqg_and_blkg_put(struct bfq_group *bfqg) {}
 
 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
 {
     struct bfq_group *bfqg;
     int i;
 
     bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
     if (!bfqg)
         return NULL;
 
     for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
         bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
 
     return bfqg;
 }
 #endif  /* CONFIG_BFQ_GROUP_IOSCHED */

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