/* * Common Block IO controller cgroup interface * * Based on ideas and code from CFQ, CFS and BFQ: * Copyright (C) 2003 Jens Axboe * * Copyright (C) 2008 Fabio Checconi * Paolo Valente * * Copyright (C) 2009 Vivek Goyal * Nauman Rafique */ #include #include #include #include #include #include #include #include #include #include "blk-cgroup.h" #include "blk.h" #define MAX_KEY_LEN 100 static DEFINE_SPINLOCK(blkio_list_lock); static LIST_HEAD(blkio_list); static DEFINE_MUTEX(all_q_mutex); static LIST_HEAD(all_q_list); /* List of groups pending per cpu stats allocation */ static DEFINE_SPINLOCK(alloc_list_lock); static LIST_HEAD(alloc_list); static void blkio_stat_alloc_fn(struct work_struct *); static DECLARE_DELAYED_WORK(blkio_stat_alloc_work, blkio_stat_alloc_fn); struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT }; EXPORT_SYMBOL_GPL(blkio_root_cgroup); static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES]; static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *, struct cgroup *); static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *, struct cgroup_taskset *); static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *, struct cgroup_taskset *); static int blkiocg_pre_destroy(struct cgroup_subsys *, struct cgroup *); static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *); static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *); /* for encoding cft->private value on file */ #define BLKIOFILE_PRIVATE(x, val) (((x) << 16) | (val)) /* What policy owns the file, proportional or throttle */ #define BLKIOFILE_POLICY(val) (((val) >> 16) & 0xffff) #define BLKIOFILE_ATTR(val) ((val) & 0xffff) struct cgroup_subsys blkio_subsys = { .name = "blkio", .create = blkiocg_create, .can_attach = blkiocg_can_attach, .attach = blkiocg_attach, .pre_destroy = blkiocg_pre_destroy, .destroy = blkiocg_destroy, .populate = blkiocg_populate, .subsys_id = blkio_subsys_id, .module = THIS_MODULE, }; EXPORT_SYMBOL_GPL(blkio_subsys); struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), struct blkio_cgroup, css); } EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup); static struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk) { return container_of(task_subsys_state(tsk, blkio_subsys_id), struct blkio_cgroup, css); } struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio) { if (bio && bio->bi_css) return container_of(bio->bi_css, struct blkio_cgroup, css); return task_blkio_cgroup(current); } EXPORT_SYMBOL_GPL(bio_blkio_cgroup); static inline void blkio_update_group_weight(struct blkio_group *blkg, int plid, unsigned int weight) { struct blkio_policy_type *blkiop; list_for_each_entry(blkiop, &blkio_list, list) { /* If this policy does not own the blkg, do not send updates */ if (blkiop->plid != plid) continue; if (blkiop->ops.blkio_update_group_weight_fn) blkiop->ops.blkio_update_group_weight_fn(blkg->q, blkg, weight); } } static inline void blkio_update_group_bps(struct blkio_group *blkg, int plid, u64 bps, int fileid) { struct blkio_policy_type *blkiop; list_for_each_entry(blkiop, &blkio_list, list) { /* If this policy does not own the blkg, do not send updates */ if (blkiop->plid != plid) continue; if (fileid == BLKIO_THROTL_read_bps_device && blkiop->ops.blkio_update_group_read_bps_fn) blkiop->ops.blkio_update_group_read_bps_fn(blkg->q, blkg, bps); if (fileid == BLKIO_THROTL_write_bps_device && blkiop->ops.blkio_update_group_write_bps_fn) blkiop->ops.blkio_update_group_write_bps_fn(blkg->q, blkg, bps); } } static inline void blkio_update_group_iops(struct blkio_group *blkg, int plid, unsigned int iops, int fileid) { struct blkio_policy_type *blkiop; list_for_each_entry(blkiop, &blkio_list, list) { /* If this policy does not own the blkg, do not send updates */ if (blkiop->plid != plid) continue; if (fileid == BLKIO_THROTL_read_iops_device && blkiop->ops.blkio_update_group_read_iops_fn) blkiop->ops.blkio_update_group_read_iops_fn(blkg->q, blkg, iops); if (fileid == BLKIO_THROTL_write_iops_device && blkiop->ops.blkio_update_group_write_iops_fn) blkiop->ops.blkio_update_group_write_iops_fn(blkg->q, blkg,iops); } } /* * Add to the appropriate stat variable depending on the request type. * This should be called with the blkg->stats_lock held. */ static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction, bool sync) { if (direction) stat[BLKIO_STAT_WRITE] += add; else stat[BLKIO_STAT_READ] += add; if (sync) stat[BLKIO_STAT_SYNC] += add; else stat[BLKIO_STAT_ASYNC] += add; } /* * Decrements the appropriate stat variable if non-zero depending on the * request type. Panics on value being zero. * This should be called with the blkg->stats_lock held. */ static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync) { if (direction) { BUG_ON(stat[BLKIO_STAT_WRITE] == 0); stat[BLKIO_STAT_WRITE]--; } else { BUG_ON(stat[BLKIO_STAT_READ] == 0); stat[BLKIO_STAT_READ]--; } if (sync) { BUG_ON(stat[BLKIO_STAT_SYNC] == 0); stat[BLKIO_STAT_SYNC]--; } else { BUG_ON(stat[BLKIO_STAT_ASYNC] == 0); stat[BLKIO_STAT_ASYNC]--; } } #ifdef CONFIG_DEBUG_BLK_CGROUP /* This should be called with the blkg->stats_lock held. */ static void blkio_set_start_group_wait_time(struct blkio_group *blkg, struct blkio_policy_type *pol, struct blkio_group *curr_blkg) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; if (blkio_blkg_waiting(&pd->stats)) return; if (blkg == curr_blkg) return; pd->stats.start_group_wait_time = sched_clock(); blkio_mark_blkg_waiting(&pd->stats); } /* This should be called with the blkg->stats_lock held. */ static void blkio_update_group_wait_time(struct blkio_group_stats *stats) { unsigned long long now; if (!blkio_blkg_waiting(stats)) return; now = sched_clock(); if (time_after64(now, stats->start_group_wait_time)) stats->group_wait_time += now - stats->start_group_wait_time; blkio_clear_blkg_waiting(stats); } /* This should be called with the blkg->stats_lock held. */ static void blkio_end_empty_time(struct blkio_group_stats *stats) { unsigned long long now; if (!blkio_blkg_empty(stats)) return; now = sched_clock(); if (time_after64(now, stats->start_empty_time)) stats->empty_time += now - stats->start_empty_time; blkio_clear_blkg_empty(stats); } void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg, struct blkio_policy_type *pol) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; spin_lock_irqsave(&blkg->stats_lock, flags); BUG_ON(blkio_blkg_idling(&pd->stats)); pd->stats.start_idle_time = sched_clock(); blkio_mark_blkg_idling(&pd->stats); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats); void blkiocg_update_idle_time_stats(struct blkio_group *blkg, struct blkio_policy_type *pol) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; unsigned long long now; struct blkio_group_stats *stats; spin_lock_irqsave(&blkg->stats_lock, flags); stats = &pd->stats; if (blkio_blkg_idling(stats)) { now = sched_clock(); if (time_after64(now, stats->start_idle_time)) stats->idle_time += now - stats->start_idle_time; blkio_clear_blkg_idling(stats); } spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats); void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg, struct blkio_policy_type *pol) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; struct blkio_group_stats *stats; spin_lock_irqsave(&blkg->stats_lock, flags); stats = &pd->stats; stats->avg_queue_size_sum += stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] + stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]; stats->avg_queue_size_samples++; blkio_update_group_wait_time(stats); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats); void blkiocg_set_start_empty_time(struct blkio_group *blkg, struct blkio_policy_type *pol) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; struct blkio_group_stats *stats; spin_lock_irqsave(&blkg->stats_lock, flags); stats = &pd->stats; if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] || stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) { spin_unlock_irqrestore(&blkg->stats_lock, flags); return; } /* * group is already marked empty. This can happen if cfqq 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(blkio_blkg_empty(stats)) { spin_unlock_irqrestore(&blkg->stats_lock, flags); return; } stats->start_empty_time = sched_clock(); blkio_mark_blkg_empty(stats); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time); void blkiocg_update_dequeue_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, unsigned long dequeue) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; pd->stats.dequeue += dequeue; } EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats); #else static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg, struct blkio_policy_type *pol, struct blkio_group *curr_blkg) { } static inline void blkio_end_empty_time(struct blkio_group_stats *stats) { } #endif void blkiocg_update_io_add_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, struct blkio_group *curr_blkg, bool direction, bool sync) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; spin_lock_irqsave(&blkg->stats_lock, flags); blkio_add_stat(pd->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction, sync); blkio_end_empty_time(&pd->stats); blkio_set_start_group_wait_time(blkg, pol, curr_blkg); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats); void blkiocg_update_io_remove_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, bool direction, bool sync) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; spin_lock_irqsave(&blkg->stats_lock, flags); blkio_check_and_dec_stat(pd->stats.stat_arr[BLKIO_STAT_QUEUED], direction, sync); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats); void blkiocg_update_timeslice_used(struct blkio_group *blkg, struct blkio_policy_type *pol, unsigned long time, unsigned long unaccounted_time) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; unsigned long flags; spin_lock_irqsave(&blkg->stats_lock, flags); pd->stats.time += time; #ifdef CONFIG_DEBUG_BLK_CGROUP pd->stats.unaccounted_time += unaccounted_time; #endif spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used); /* * should be called under rcu read lock or queue lock to make sure blkg pointer * is valid. */ void blkiocg_update_dispatch_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, uint64_t bytes, bool direction, bool sync) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; struct blkio_group_stats_cpu *stats_cpu; unsigned long flags; /* If per cpu stats are not allocated yet, don't do any accounting. */ if (pd->stats_cpu == NULL) return; /* * Disabling interrupts to provide mutual exclusion between two * writes on same cpu. It probably is not needed for 64bit. Not * optimizing that case yet. */ local_irq_save(flags); stats_cpu = this_cpu_ptr(pd->stats_cpu); u64_stats_update_begin(&stats_cpu->syncp); stats_cpu->sectors += bytes >> 9; blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICED], 1, direction, sync); blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICE_BYTES], bytes, direction, sync); u64_stats_update_end(&stats_cpu->syncp); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats); void blkiocg_update_completion_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, uint64_t start_time, uint64_t io_start_time, bool direction, bool sync) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; struct blkio_group_stats *stats; unsigned long flags; unsigned long long now = sched_clock(); spin_lock_irqsave(&blkg->stats_lock, flags); stats = &pd->stats; if (time_after64(now, io_start_time)) blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME], now - io_start_time, direction, sync); if (time_after64(io_start_time, start_time)) blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME], io_start_time - start_time, direction, sync); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats); /* Merged stats are per cpu. */ void blkiocg_update_io_merged_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, bool direction, bool sync) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; struct blkio_group_stats *stats; unsigned long flags; spin_lock_irqsave(&blkg->stats_lock, flags); stats = &pd->stats; blkio_add_stat(stats->stat_arr[BLKIO_STAT_MERGED], 1, direction, sync); spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats); /* * Worker for allocating per cpu stat for blk groups. This is scheduled on * the system_nrt_wq once there are some groups on the alloc_list waiting * for allocation. */ static void blkio_stat_alloc_fn(struct work_struct *work) { static void *pcpu_stats[BLKIO_NR_POLICIES]; struct delayed_work *dwork = to_delayed_work(work); struct blkio_group *blkg; int i; bool empty = false; alloc_stats: for (i = 0; i < BLKIO_NR_POLICIES; i++) { if (pcpu_stats[i] != NULL) continue; pcpu_stats[i] = alloc_percpu(struct blkio_group_stats_cpu); /* Allocation failed. Try again after some time. */ if (pcpu_stats[i] == NULL) { queue_delayed_work(system_nrt_wq, dwork, msecs_to_jiffies(10)); return; } } spin_lock_irq(&blkio_list_lock); spin_lock(&alloc_list_lock); /* cgroup got deleted or queue exited. */ if (!list_empty(&alloc_list)) { blkg = list_first_entry(&alloc_list, struct blkio_group, alloc_node); for (i = 0; i < BLKIO_NR_POLICIES; i++) { struct blkg_policy_data *pd = blkg->pd[i]; if (blkio_policy[i] && pd && !pd->stats_cpu) swap(pd->stats_cpu, pcpu_stats[i]); } list_del_init(&blkg->alloc_node); } empty = list_empty(&alloc_list); spin_unlock(&alloc_list_lock); spin_unlock_irq(&blkio_list_lock); if (!empty) goto alloc_stats; } /** * blkg_free - free a blkg * @blkg: blkg to free * * Free @blkg which may be partially allocated. */ static void blkg_free(struct blkio_group *blkg) { int i; if (!blkg) return; for (i = 0; i < BLKIO_NR_POLICIES; i++) { struct blkg_policy_data *pd = blkg->pd[i]; if (pd) { free_percpu(pd->stats_cpu); kfree(pd); } } kfree(blkg); } /** * blkg_alloc - allocate a blkg * @blkcg: block cgroup the new blkg is associated with * @q: request_queue the new blkg is associated with * * Allocate a new blkg assocating @blkcg and @q. */ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg, struct request_queue *q) { struct blkio_group *blkg; int i; /* alloc and init base part */ blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node); if (!blkg) return NULL; spin_lock_init(&blkg->stats_lock); blkg->q = q; INIT_LIST_HEAD(&blkg->q_node); INIT_LIST_HEAD(&blkg->alloc_node); blkg->blkcg = blkcg; blkg->refcnt = 1; cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path)); for (i = 0; i < BLKIO_NR_POLICIES; i++) { struct blkio_policy_type *pol = blkio_policy[i]; struct blkg_policy_data *pd; if (!pol) continue; /* alloc per-policy data and attach it to blkg */ pd = kzalloc_node(sizeof(*pd) + pol->pdata_size, GFP_ATOMIC, q->node); if (!pd) { blkg_free(blkg); return NULL; } blkg->pd[i] = pd; pd->blkg = blkg; } /* invoke per-policy init */ for (i = 0; i < BLKIO_NR_POLICIES; i++) { struct blkio_policy_type *pol = blkio_policy[i]; if (pol) pol->ops.blkio_init_group_fn(blkg); } return blkg; } struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg, struct request_queue *q, enum blkio_policy_id plid, bool for_root) __releases(q->queue_lock) __acquires(q->queue_lock) { struct blkio_group *blkg; WARN_ON_ONCE(!rcu_read_lock_held()); lockdep_assert_held(q->queue_lock); /* * This could be the first entry point of blkcg implementation and * we shouldn't allow anything to go through for a bypassing queue. * The following can be removed if blkg lookup is guaranteed to * fail on a bypassing queue. */ if (unlikely(blk_queue_bypass(q)) && !for_root) return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY); blkg = blkg_lookup(blkcg, q); if (blkg) return blkg; /* blkg holds a reference to blkcg */ if (!css_tryget(&blkcg->css)) return ERR_PTR(-EINVAL); /* * Allocate and initialize. */ blkg = blkg_alloc(blkcg, q); /* did alloc fail? */ if (unlikely(!blkg)) { blkg = ERR_PTR(-ENOMEM); goto out; } /* insert */ spin_lock(&blkcg->lock); hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); list_add(&blkg->q_node, &q->blkg_list); spin_unlock(&blkcg->lock); spin_lock(&alloc_list_lock); list_add(&blkg->alloc_node, &alloc_list); /* Queue per cpu stat allocation from worker thread. */ queue_delayed_work(system_nrt_wq, &blkio_stat_alloc_work, 0); spin_unlock(&alloc_list_lock); out: return blkg; } EXPORT_SYMBOL_GPL(blkg_lookup_create); /* called under rcu_read_lock(). */ struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg, struct request_queue *q) { struct blkio_group *blkg; struct hlist_node *n; hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) if (blkg->q == q) return blkg; return NULL; } EXPORT_SYMBOL_GPL(blkg_lookup); static void blkg_destroy(struct blkio_group *blkg) { struct request_queue *q = blkg->q; struct blkio_cgroup *blkcg = blkg->blkcg; lockdep_assert_held(q->queue_lock); lockdep_assert_held(&blkcg->lock); /* Something wrong if we are trying to remove same group twice */ WARN_ON_ONCE(list_empty(&blkg->q_node)); WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); list_del_init(&blkg->q_node); hlist_del_init_rcu(&blkg->blkcg_node); spin_lock(&alloc_list_lock); list_del_init(&blkg->alloc_node); spin_unlock(&alloc_list_lock); /* * Put the reference taken at the time of creation so that when all * queues are gone, group can be destroyed. */ blkg_put(blkg); } /* * XXX: This updates blkg policy data in-place for root blkg, which is * necessary across elevator switch and policy registration as root blkgs * aren't shot down. This broken and racy implementation is temporary. * Eventually, blkg shoot down will be replaced by proper in-place update. */ void update_root_blkg_pd(struct request_queue *q, enum blkio_policy_id plid) { struct blkio_policy_type *pol = blkio_policy[plid]; struct blkio_group *blkg = blkg_lookup(&blkio_root_cgroup, q); struct blkg_policy_data *pd; if (!blkg) return; kfree(blkg->pd[plid]); blkg->pd[plid] = NULL; if (!pol) return; pd = kzalloc(sizeof(*pd) + pol->pdata_size, GFP_KERNEL); WARN_ON_ONCE(!pd); pd->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu); WARN_ON_ONCE(!pd->stats_cpu); blkg->pd[plid] = pd; pd->blkg = blkg; pol->ops.blkio_init_group_fn(blkg); } EXPORT_SYMBOL_GPL(update_root_blkg_pd); /** * blkg_destroy_all - destroy all blkgs associated with a request_queue * @q: request_queue of interest * @destroy_root: whether to destroy root blkg or not * * Destroy blkgs associated with @q. If @destroy_root is %true, all are * destroyed; otherwise, root blkg is left alone. */ void blkg_destroy_all(struct request_queue *q, bool destroy_root) { struct blkio_group *blkg, *n; spin_lock_irq(q->queue_lock); list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { struct blkio_cgroup *blkcg = blkg->blkcg; /* skip root? */ if (!destroy_root && blkg->blkcg == &blkio_root_cgroup) continue; spin_lock(&blkcg->lock); blkg_destroy(blkg); spin_unlock(&blkcg->lock); } spin_unlock_irq(q->queue_lock); } EXPORT_SYMBOL_GPL(blkg_destroy_all); static void blkg_rcu_free(struct rcu_head *rcu_head) { blkg_free(container_of(rcu_head, struct blkio_group, rcu_head)); } void __blkg_release(struct blkio_group *blkg) { /* release the extra blkcg reference this blkg has been holding */ css_put(&blkg->blkcg->css); /* * A group is freed in rcu manner. But having an rcu lock does not * mean that one can access all the fields of blkg and assume these * are valid. For example, don't try to follow throtl_data and * request queue links. * * Having a reference to blkg under an rcu allows acess to only * values local to groups like group stats and group rate limits */ call_rcu(&blkg->rcu_head, blkg_rcu_free); } EXPORT_SYMBOL_GPL(__blkg_release); static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid) { struct blkg_policy_data *pd = blkg->pd[plid]; int cpu; if (pd->stats_cpu == NULL) return; for_each_possible_cpu(cpu) { struct blkio_group_stats_cpu *sc = per_cpu_ptr(pd->stats_cpu, cpu); sc->sectors = 0; memset(sc->stat_arr_cpu, 0, sizeof(sc->stat_arr_cpu)); } } static int blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val) { struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); struct blkio_group *blkg; struct hlist_node *n; int i; spin_lock(&blkio_list_lock); spin_lock_irq(&blkcg->lock); /* * Note that stat reset is racy - it doesn't synchronize against * stat updates. This is a debug feature which shouldn't exist * anyway. If you get hit by a race, retry. */ hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { struct blkio_policy_type *pol; list_for_each_entry(pol, &blkio_list, list) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; struct blkio_group_stats *stats = &pd->stats; /* queued stats shouldn't be cleared */ for (i = 0; i < ARRAY_SIZE(stats->stat_arr); i++) if (i != BLKIO_STAT_QUEUED) memset(stats->stat_arr[i], 0, sizeof(stats->stat_arr[i])); stats->time = 0; #ifdef CONFIG_DEBUG_BLK_CGROUP memset((void *)stats + BLKG_STATS_DEBUG_CLEAR_START, 0, BLKG_STATS_DEBUG_CLEAR_SIZE); #endif blkio_reset_stats_cpu(blkg, pol->plid); } } spin_unlock_irq(&blkcg->lock); spin_unlock(&blkio_list_lock); return 0; } static void blkio_get_key_name(enum stat_sub_type type, const char *dname, char *str, int chars_left, bool diskname_only) { snprintf(str, chars_left, "%s", dname); chars_left -= strlen(str); if (chars_left <= 0) { printk(KERN_WARNING "Possibly incorrect cgroup stat display format"); return; } if (diskname_only) return; switch (type) { case BLKIO_STAT_READ: strlcat(str, " Read", chars_left); break; case BLKIO_STAT_WRITE: strlcat(str, " Write", chars_left); break; case BLKIO_STAT_SYNC: strlcat(str, " Sync", chars_left); break; case BLKIO_STAT_ASYNC: strlcat(str, " Async", chars_left); break; case BLKIO_STAT_TOTAL: strlcat(str, " Total", chars_left); break; default: strlcat(str, " Invalid", chars_left); } } static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val, struct cgroup_map_cb *cb, const char *dname) { blkio_get_key_name(0, dname, str, chars_left, true); cb->fill(cb, str, val); return val; } static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg, int plid, enum stat_type_cpu type, enum stat_sub_type sub_type) { struct blkg_policy_data *pd = blkg->pd[plid]; int cpu; struct blkio_group_stats_cpu *stats_cpu; u64 val = 0, tval; if (pd->stats_cpu == NULL) return val; for_each_possible_cpu(cpu) { unsigned int start; stats_cpu = per_cpu_ptr(pd->stats_cpu, cpu); do { start = u64_stats_fetch_begin(&stats_cpu->syncp); if (type == BLKIO_STAT_CPU_SECTORS) tval = stats_cpu->sectors; else tval = stats_cpu->stat_arr_cpu[type][sub_type]; } while(u64_stats_fetch_retry(&stats_cpu->syncp, start)); val += tval; } return val; } static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg, int plid, struct cgroup_map_cb *cb, const char *dname, enum stat_type_cpu type) { uint64_t disk_total, val; char key_str[MAX_KEY_LEN]; enum stat_sub_type sub_type; if (type == BLKIO_STAT_CPU_SECTORS) { val = blkio_read_stat_cpu(blkg, plid, type, 0); return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, val, cb, dname); } for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL; sub_type++) { blkio_get_key_name(sub_type, dname, key_str, MAX_KEY_LEN, false); val = blkio_read_stat_cpu(blkg, plid, type, sub_type); cb->fill(cb, key_str, val); } disk_total = blkio_read_stat_cpu(blkg, plid, type, BLKIO_STAT_READ) + blkio_read_stat_cpu(blkg, plid, type, BLKIO_STAT_WRITE); blkio_get_key_name(BLKIO_STAT_TOTAL, dname, key_str, MAX_KEY_LEN, false); cb->fill(cb, key_str, disk_total); return disk_total; } /* This should be called with blkg->stats_lock held */ static uint64_t blkio_get_stat(struct blkio_group *blkg, int plid, struct cgroup_map_cb *cb, const char *dname, enum stat_type type) { struct blkg_policy_data *pd = blkg->pd[plid]; uint64_t disk_total; char key_str[MAX_KEY_LEN]; enum stat_sub_type sub_type; if (type == BLKIO_STAT_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, pd->stats.time, cb, dname); #ifdef CONFIG_DEBUG_BLK_CGROUP if (type == BLKIO_STAT_UNACCOUNTED_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, pd->stats.unaccounted_time, cb, dname); if (type == BLKIO_STAT_AVG_QUEUE_SIZE) { uint64_t sum = pd->stats.avg_queue_size_sum; uint64_t samples = pd->stats.avg_queue_size_samples; if (samples) do_div(sum, samples); else sum = 0; return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dname); } if (type == BLKIO_STAT_GROUP_WAIT_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, pd->stats.group_wait_time, cb, dname); if (type == BLKIO_STAT_IDLE_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, pd->stats.idle_time, cb, dname); if (type == BLKIO_STAT_EMPTY_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, pd->stats.empty_time, cb, dname); if (type == BLKIO_STAT_DEQUEUE) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, pd->stats.dequeue, cb, dname); #endif for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL; sub_type++) { blkio_get_key_name(sub_type, dname, key_str, MAX_KEY_LEN, false); cb->fill(cb, key_str, pd->stats.stat_arr[type][sub_type]); } disk_total = pd->stats.stat_arr[type][BLKIO_STAT_READ] + pd->stats.stat_arr[type][BLKIO_STAT_WRITE]; blkio_get_key_name(BLKIO_STAT_TOTAL, dname, key_str, MAX_KEY_LEN, false); cb->fill(cb, key_str, disk_total); return disk_total; } static int blkio_policy_parse_and_set(char *buf, enum blkio_policy_id plid, int fileid, struct blkio_cgroup *blkcg) { struct gendisk *disk = NULL; struct blkio_group *blkg = NULL; struct blkg_policy_data *pd; char *s[4], *p, *major_s = NULL, *minor_s = NULL; unsigned long major, minor; int i = 0, ret = -EINVAL; int part; dev_t dev; u64 temp; memset(s, 0, sizeof(s)); while ((p = strsep(&buf, " ")) != NULL) { if (!*p) continue; s[i++] = p; /* Prevent from inputing too many things */ if (i == 3) break; } if (i != 2) goto out; p = strsep(&s[0], ":"); if (p != NULL) major_s = p; else goto out; minor_s = s[0]; if (!minor_s) goto out; if (strict_strtoul(major_s, 10, &major)) goto out; if (strict_strtoul(minor_s, 10, &minor)) goto out; dev = MKDEV(major, minor); if (strict_strtoull(s[1], 10, &temp)) goto out; disk = get_gendisk(dev, &part); if (!disk || part) goto out; rcu_read_lock(); spin_lock_irq(disk->queue->queue_lock); blkg = blkg_lookup_create(blkcg, disk->queue, plid, false); spin_unlock_irq(disk->queue->queue_lock); if (IS_ERR(blkg)) { ret = PTR_ERR(blkg); goto out_unlock; } pd = blkg->pd[plid]; switch (plid) { case BLKIO_POLICY_PROP: if ((temp < BLKIO_WEIGHT_MIN && temp > 0) || temp > BLKIO_WEIGHT_MAX) goto out_unlock; pd->conf.weight = temp; blkio_update_group_weight(blkg, plid, temp ?: blkcg->weight); break; case BLKIO_POLICY_THROTL: switch(fileid) { case BLKIO_THROTL_read_bps_device: pd->conf.bps[READ] = temp; blkio_update_group_bps(blkg, plid, temp ?: -1, fileid); break; case BLKIO_THROTL_write_bps_device: pd->conf.bps[WRITE] = temp; blkio_update_group_bps(blkg, plid, temp ?: -1, fileid); break; case BLKIO_THROTL_read_iops_device: if (temp > THROTL_IOPS_MAX) goto out_unlock; pd->conf.iops[READ] = temp; blkio_update_group_iops(blkg, plid, temp ?: -1, fileid); break; case BLKIO_THROTL_write_iops_device: if (temp > THROTL_IOPS_MAX) goto out_unlock; pd->conf.iops[WRITE] = temp; blkio_update_group_iops(blkg, plid, temp ?: -1, fileid); break; } break; default: BUG(); } ret = 0; out_unlock: rcu_read_unlock(); out: put_disk(disk); /* * If queue was bypassing, we should retry. Do so after a short * msleep(). It isn't strictly necessary but queue can be * bypassing for some time and it's always nice to avoid busy * looping. */ if (ret == -EBUSY) { msleep(10); return restart_syscall(); } return ret; } static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft, const char *buffer) { int ret = 0; char *buf; struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp); enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); int fileid = BLKIOFILE_ATTR(cft->private); buf = kstrdup(buffer, GFP_KERNEL); if (!buf) return -ENOMEM; ret = blkio_policy_parse_and_set(buf, plid, fileid, blkcg); kfree(buf); return ret; } static const char *blkg_dev_name(struct blkio_group *blkg) { /* some drivers (floppy) instantiate a queue w/o disk registered */ if (blkg->q->backing_dev_info.dev) return dev_name(blkg->q->backing_dev_info.dev); return NULL; } static void blkio_print_group_conf(struct cftype *cft, struct blkio_group *blkg, struct seq_file *m) { int plid = BLKIOFILE_POLICY(cft->private); int fileid = BLKIOFILE_ATTR(cft->private); struct blkg_policy_data *pd = blkg->pd[plid]; const char *dname = blkg_dev_name(blkg); int rw = WRITE; if (!dname) return; switch (plid) { case BLKIO_POLICY_PROP: if (pd->conf.weight) seq_printf(m, "%s\t%u\n", dname, pd->conf.weight); break; case BLKIO_POLICY_THROTL: switch (fileid) { case BLKIO_THROTL_read_bps_device: rw = READ; case BLKIO_THROTL_write_bps_device: if (pd->conf.bps[rw]) seq_printf(m, "%s\t%llu\n", dname, pd->conf.bps[rw]); break; case BLKIO_THROTL_read_iops_device: rw = READ; case BLKIO_THROTL_write_iops_device: if (pd->conf.iops[rw]) seq_printf(m, "%s\t%u\n", dname, pd->conf.iops[rw]); break; } break; default: BUG(); } } /* cgroup files which read their data from policy nodes end up here */ static void blkio_read_conf(struct cftype *cft, struct blkio_cgroup *blkcg, struct seq_file *m) { struct blkio_group *blkg; struct hlist_node *n; spin_lock_irq(&blkcg->lock); hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) blkio_print_group_conf(cft, blkg, m); spin_unlock_irq(&blkcg->lock); } static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft, struct seq_file *m) { struct blkio_cgroup *blkcg; enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); int name = BLKIOFILE_ATTR(cft->private); blkcg = cgroup_to_blkio_cgroup(cgrp); switch(plid) { case BLKIO_POLICY_PROP: switch(name) { case BLKIO_PROP_weight_device: blkio_read_conf(cft, blkcg, m); return 0; default: BUG(); } break; case BLKIO_POLICY_THROTL: switch(name){ case BLKIO_THROTL_read_bps_device: case BLKIO_THROTL_write_bps_device: case BLKIO_THROTL_read_iops_device: case BLKIO_THROTL_write_iops_device: blkio_read_conf(cft, blkcg, m); return 0; default: BUG(); } break; default: BUG(); } return 0; } static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg, struct cftype *cft, struct cgroup_map_cb *cb, enum stat_type type, bool show_total, bool pcpu) { struct blkio_group *blkg; struct hlist_node *n; uint64_t cgroup_total = 0; spin_lock_irq(&blkcg->lock); hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { const char *dname = blkg_dev_name(blkg); int plid = BLKIOFILE_POLICY(cft->private); if (!dname) continue; if (pcpu) { cgroup_total += blkio_get_stat_cpu(blkg, plid, cb, dname, type); } else { spin_lock(&blkg->stats_lock); cgroup_total += blkio_get_stat(blkg, plid, cb, dname, type); spin_unlock(&blkg->stats_lock); } } if (show_total) cb->fill(cb, "Total", cgroup_total); spin_unlock_irq(&blkcg->lock); return 0; } /* All map kind of cgroup file get serviced by this function */ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, struct cgroup_map_cb *cb) { struct blkio_cgroup *blkcg; enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); int name = BLKIOFILE_ATTR(cft->private); blkcg = cgroup_to_blkio_cgroup(cgrp); switch(plid) { case BLKIO_POLICY_PROP: switch(name) { case BLKIO_PROP_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_TIME, 0, 0); case BLKIO_PROP_sectors: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_CPU_SECTORS, 0, 1); case BLKIO_PROP_io_service_bytes: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1); case BLKIO_PROP_io_serviced: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_CPU_SERVICED, 1, 1); case BLKIO_PROP_io_service_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_SERVICE_TIME, 1, 0); case BLKIO_PROP_io_wait_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_WAIT_TIME, 1, 0); case BLKIO_PROP_io_merged: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_MERGED, 1, 0); case BLKIO_PROP_io_queued: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_QUEUED, 1, 0); #ifdef CONFIG_DEBUG_BLK_CGROUP case BLKIO_PROP_unaccounted_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_UNACCOUNTED_TIME, 0, 0); case BLKIO_PROP_dequeue: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_DEQUEUE, 0, 0); case BLKIO_PROP_avg_queue_size: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_AVG_QUEUE_SIZE, 0, 0); case BLKIO_PROP_group_wait_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_GROUP_WAIT_TIME, 0, 0); case BLKIO_PROP_idle_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_IDLE_TIME, 0, 0); case BLKIO_PROP_empty_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_EMPTY_TIME, 0, 0); #endif default: BUG(); } break; case BLKIO_POLICY_THROTL: switch(name){ case BLKIO_THROTL_io_service_bytes: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1); case BLKIO_THROTL_io_serviced: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_CPU_SERVICED, 1, 1); default: BUG(); } break; default: BUG(); } return 0; } static int blkio_weight_write(struct blkio_cgroup *blkcg, int plid, u64 val) { struct blkio_group *blkg; struct hlist_node *n; if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX) return -EINVAL; spin_lock(&blkio_list_lock); spin_lock_irq(&blkcg->lock); blkcg->weight = (unsigned int)val; hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { struct blkg_policy_data *pd = blkg->pd[plid]; if (!pd->conf.weight) blkio_update_group_weight(blkg, plid, blkcg->weight); } spin_unlock_irq(&blkcg->lock); spin_unlock(&blkio_list_lock); return 0; } static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) { struct blkio_cgroup *blkcg; enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); int name = BLKIOFILE_ATTR(cft->private); blkcg = cgroup_to_blkio_cgroup(cgrp); switch(plid) { case BLKIO_POLICY_PROP: switch(name) { case BLKIO_PROP_weight: return (u64)blkcg->weight; } break; default: BUG(); } return 0; } static int blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val) { struct blkio_cgroup *blkcg; enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); int name = BLKIOFILE_ATTR(cft->private); blkcg = cgroup_to_blkio_cgroup(cgrp); switch(plid) { case BLKIO_POLICY_PROP: switch(name) { case BLKIO_PROP_weight: return blkio_weight_write(blkcg, plid, val); } break; default: BUG(); } return 0; } struct cftype blkio_files[] = { { .name = "weight_device", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_weight_device), .read_seq_string = blkiocg_file_read, .write_string = blkiocg_file_write, .max_write_len = 256, }, { .name = "weight", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_weight), .read_u64 = blkiocg_file_read_u64, .write_u64 = blkiocg_file_write_u64, }, { .name = "time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_time), .read_map = blkiocg_file_read_map, }, { .name = "sectors", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_sectors), .read_map = blkiocg_file_read_map, }, { .name = "io_service_bytes", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_service_bytes), .read_map = blkiocg_file_read_map, }, { .name = "io_serviced", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_serviced), .read_map = blkiocg_file_read_map, }, { .name = "io_service_time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_service_time), .read_map = blkiocg_file_read_map, }, { .name = "io_wait_time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_wait_time), .read_map = blkiocg_file_read_map, }, { .name = "io_merged", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_merged), .read_map = blkiocg_file_read_map, }, { .name = "io_queued", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_io_queued), .read_map = blkiocg_file_read_map, }, { .name = "reset_stats", .write_u64 = blkiocg_reset_stats, }, #ifdef CONFIG_BLK_DEV_THROTTLING { .name = "throttle.read_bps_device", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL, BLKIO_THROTL_read_bps_device), .read_seq_string = blkiocg_file_read, .write_string = blkiocg_file_write, .max_write_len = 256, }, { .name = "throttle.write_bps_device", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL, BLKIO_THROTL_write_bps_device), .read_seq_string = blkiocg_file_read, .write_string = blkiocg_file_write, .max_write_len = 256, }, { .name = "throttle.read_iops_device", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL, BLKIO_THROTL_read_iops_device), .read_seq_string = blkiocg_file_read, .write_string = blkiocg_file_write, .max_write_len = 256, }, { .name = "throttle.write_iops_device", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL, BLKIO_THROTL_write_iops_device), .read_seq_string = blkiocg_file_read, .write_string = blkiocg_file_write, .max_write_len = 256, }, { .name = "throttle.io_service_bytes", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL, BLKIO_THROTL_io_service_bytes), .read_map = blkiocg_file_read_map, }, { .name = "throttle.io_serviced", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL, BLKIO_THROTL_io_serviced), .read_map = blkiocg_file_read_map, }, #endif /* CONFIG_BLK_DEV_THROTTLING */ #ifdef CONFIG_DEBUG_BLK_CGROUP { .name = "avg_queue_size", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_avg_queue_size), .read_map = blkiocg_file_read_map, }, { .name = "group_wait_time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_group_wait_time), .read_map = blkiocg_file_read_map, }, { .name = "idle_time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_idle_time), .read_map = blkiocg_file_read_map, }, { .name = "empty_time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_empty_time), .read_map = blkiocg_file_read_map, }, { .name = "dequeue", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_dequeue), .read_map = blkiocg_file_read_map, }, { .name = "unaccounted_time", .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, BLKIO_PROP_unaccounted_time), .read_map = blkiocg_file_read_map, }, #endif }; static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup) { return cgroup_add_files(cgroup, subsys, blkio_files, ARRAY_SIZE(blkio_files)); } /** * blkiocg_pre_destroy - cgroup pre_destroy callback * @subsys: cgroup subsys * @cgroup: cgroup of interest * * This function is called when @cgroup is about to go away and responsible * for shooting down all blkgs associated with @cgroup. blkgs should be * removed while holding both q and blkcg locks. As blkcg lock is nested * inside q lock, this function performs reverse double lock dancing. * * This is the blkcg counterpart of ioc_release_fn(). */ static int blkiocg_pre_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) { struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); spin_lock_irq(&blkcg->lock); while (!hlist_empty(&blkcg->blkg_list)) { struct blkio_group *blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group, blkcg_node); struct request_queue *q = blkg->q; if (spin_trylock(q->queue_lock)) { blkg_destroy(blkg); spin_unlock(q->queue_lock); } else { spin_unlock_irq(&blkcg->lock); cpu_relax(); spin_lock(&blkcg->lock); } } spin_unlock_irq(&blkcg->lock); return 0; } static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) { struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); if (blkcg != &blkio_root_cgroup) kfree(blkcg); } static struct cgroup_subsys_state * blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) { struct blkio_cgroup *blkcg; struct cgroup *parent = cgroup->parent; if (!parent) { blkcg = &blkio_root_cgroup; goto done; } blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); if (!blkcg) return ERR_PTR(-ENOMEM); blkcg->weight = BLKIO_WEIGHT_DEFAULT; done: spin_lock_init(&blkcg->lock); INIT_HLIST_HEAD(&blkcg->blkg_list); return &blkcg->css; } /** * blkcg_init_queue - initialize blkcg part of request queue * @q: request_queue to initialize * * Called from blk_alloc_queue_node(). Responsible for initializing blkcg * part of new request_queue @q. * * RETURNS: * 0 on success, -errno on failure. */ int blkcg_init_queue(struct request_queue *q) { int ret; might_sleep(); ret = blk_throtl_init(q); if (ret) return ret; mutex_lock(&all_q_mutex); INIT_LIST_HEAD(&q->all_q_node); list_add_tail(&q->all_q_node, &all_q_list); mutex_unlock(&all_q_mutex); return 0; } /** * blkcg_drain_queue - drain blkcg part of request_queue * @q: request_queue to drain * * Called from blk_drain_queue(). Responsible for draining blkcg part. */ void blkcg_drain_queue(struct request_queue *q) { lockdep_assert_held(q->queue_lock); blk_throtl_drain(q); } /** * blkcg_exit_queue - exit and release blkcg part of request_queue * @q: request_queue being released * * Called from blk_release_queue(). Responsible for exiting blkcg part. */ void blkcg_exit_queue(struct request_queue *q) { mutex_lock(&all_q_mutex); list_del_init(&q->all_q_node); mutex_unlock(&all_q_mutex); blkg_destroy_all(q, true); blk_throtl_exit(q); } /* * We cannot support shared io contexts, as we have no mean to support * two tasks with the same ioc in two different groups without major rework * of the main cic data structures. For now we allow a task to change * its cgroup only if it's the only owner of its ioc. */ static int blkiocg_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup_taskset *tset) { struct task_struct *task; struct io_context *ioc; int ret = 0; /* task_lock() is needed to avoid races with exit_io_context() */ cgroup_taskset_for_each(task, cgrp, tset) { task_lock(task); ioc = task->io_context; if (ioc && atomic_read(&ioc->nr_tasks) > 1) ret = -EINVAL; task_unlock(task); if (ret) break; } return ret; } static void blkiocg_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup_taskset *tset) { struct task_struct *task; struct io_context *ioc; cgroup_taskset_for_each(task, cgrp, tset) { /* we don't lose anything even if ioc allocation fails */ ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE); if (ioc) { ioc_cgroup_changed(ioc); put_io_context(ioc); } } } static void blkcg_bypass_start(void) __acquires(&all_q_mutex) { struct request_queue *q; mutex_lock(&all_q_mutex); list_for_each_entry(q, &all_q_list, all_q_node) { blk_queue_bypass_start(q); blkg_destroy_all(q, false); } } static void blkcg_bypass_end(void) __releases(&all_q_mutex) { struct request_queue *q; list_for_each_entry(q, &all_q_list, all_q_node) blk_queue_bypass_end(q); mutex_unlock(&all_q_mutex); } void blkio_policy_register(struct blkio_policy_type *blkiop) { struct request_queue *q; blkcg_bypass_start(); spin_lock(&blkio_list_lock); BUG_ON(blkio_policy[blkiop->plid]); blkio_policy[blkiop->plid] = blkiop; list_add_tail(&blkiop->list, &blkio_list); spin_unlock(&blkio_list_lock); list_for_each_entry(q, &all_q_list, all_q_node) update_root_blkg_pd(q, blkiop->plid); blkcg_bypass_end(); } EXPORT_SYMBOL_GPL(blkio_policy_register); void blkio_policy_unregister(struct blkio_policy_type *blkiop) { struct request_queue *q; blkcg_bypass_start(); spin_lock(&blkio_list_lock); BUG_ON(blkio_policy[blkiop->plid] != blkiop); blkio_policy[blkiop->plid] = NULL; list_del_init(&blkiop->list); spin_unlock(&blkio_list_lock); list_for_each_entry(q, &all_q_list, all_q_node) update_root_blkg_pd(q, blkiop->plid); blkcg_bypass_end(); } EXPORT_SYMBOL_GPL(blkio_policy_unregister);