| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Paolo Valente | 4193 | 71.16% | 11 | 34.38% |
| Luca Miccio | 493 | 8.37% | 1 | 3.12% |
| Fam Zheng | 471 | 7.99% | 2 | 6.25% |
| Christoph Hellwig | 384 | 6.52% | 7 | 21.88% |
| Tejun Heo | 282 | 4.79% | 3 | 9.38% |
| Omar Sandoval | 30 | 0.51% | 1 | 3.12% |
| Carlo Nonato | 9 | 0.15% | 1 | 3.12% |
| Bart Van Assche | 8 | 0.14% | 1 | 3.12% |
| Maciej S. Szmigiero | 8 | 0.14% | 1 | 3.12% |
| Hou Tao | 6 | 0.10% | 1 | 3.12% |
| Konstantin Khlebnikov | 5 | 0.08% | 1 | 3.12% |
| Dennis Zhou | 2 | 0.03% | 1 | 3.12% |
| Angelo Ruocco | 1 | 0.02% | 1 | 3.12% |
| Total | 5892 | 32 |
// 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/elevator.h> #include <linux/ktime.h> #include <linux/rbtree.h> #include <linux/ioprio.h> #include <linux/sbitmap.h> #include <linux/delay.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, unsigned int op) { blkg_rwstat_add(&bfqg->stats.queued, op, 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, unsigned int op) { blkg_rwstat_add(&bfqg->stats.queued, op, -1); } void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { blkg_rwstat_add(&bfqg->stats.merged, op, 1); } void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns, u64 io_start_time_ns, unsigned int op) { struct bfqg_stats *stats = &bfqg->stats; u64 now = ktime_get_ns(); if (now > io_start_time_ns) blkg_rwstat_add(&stats->service_time, op, now - io_start_time_ns); if (io_start_time_ns > start_time_ns) blkg_rwstat_add(&stats->wait_time, op, 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, unsigned int op) { } void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { } void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { } void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns, u64 io_start_time_ns, unsigned int op) { } 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); } 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)) return -ENOMEM; #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)) { bfqg_stats_exit(stats); return -ENOMEM; } #endif return 0; } static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) { return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; } static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) { return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); } static 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; 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->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 struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd, struct blkcg *blkcg) { struct blkcg_gq *blkg; blkg = blkg_lookup(blkcg, bfqd->queue); if (likely(blkg)) return blkg_to_bfqg(blkg); return NULL; } struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg) { struct bfq_group *bfqg, *parent; struct bfq_entity *entity; bfqg = bfq_lookup_bfqg(bfqd, blkcg); if (unlikely(!bfqg)) return NULL; /* * 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); } } return bfqg; } /** * 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; /* * 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(bfqq_group(bfqq)); 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 @cgroup. * @bfqd: the queue descriptor. * @bic: the bic to move. * @blkcg: the blk-cgroup 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) * * NOTE: an alternative approach might have been to store the current * cgroup in bfqq and getting a reference to it, reducing the lookup * time here, at the price of slightly more complex code. */ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, struct bfq_io_cq *bic, struct blkcg *blkcg) { struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); struct bfq_group *bfqg; struct bfq_entity *entity; bfqg = bfq_find_set_group(bfqd, blkcg); if (unlikely(!bfqg)) bfqg = bfqd->root_group; 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) { entity = &sync_bfqq->entity; if (entity->sched_data != &bfqg->sched_data) bfq_bfqq_move(bfqd, sync_bfqq, bfqg); } 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 = NULL; uint64_t serial_nr; rcu_read_lock(); serial_nr = __bio_blkcg(bio)->css.serial_nr; /* * Check whether blkcg has changed. The condition may trigger * spuriously on a newly created cic but there's no harm. */ if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) goto out; bfqg = __bfq_bic_change_cgroup(bfqd, bic, __bio_blkcg(bio)); /* * 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; out: rcu_read_unlock(); } /** * 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. */ 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. */ 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); 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_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg) { return bfqd->root_group; } struct bfq_group *bfqq_group(struct bfq_queue *bfqq) { return bfqq->bfqd->root_group; } void bfqg_and_blkg_get(struct bfq_group *bfqg) {} 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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