diff options
Diffstat (limited to 'block/blk-cgroup.c')
| -rw-r--r-- | block/blk-cgroup.c | 1745 |
1 files changed, 1032 insertions, 713 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 1eb8895be4c6..ff93c385ba5a 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -23,16 +23,18 @@ #include <linux/blkdev.h> #include <linux/backing-dev.h> #include <linux/slab.h> -#include <linux/genhd.h> #include <linux/delay.h> #include <linux/atomic.h> #include <linux/ctype.h> -#include <linux/blk-cgroup.h> -#include <linux/tracehook.h> +#include <linux/resume_user_mode.h> #include <linux/psi.h> +#include <linux/part_stat.h> #include "blk.h" +#include "blk-cgroup.h" +#include "blk-ioprio.h" +#include "blk-throttle.h" -#define MAX_KEY_LEN 100 +static void __blkcg_rstat_flush(struct blkcg *blkcg, int cpu); /* * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. @@ -55,7 +57,58 @@ static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ bool blkcg_debug_stats = false; -static struct workqueue_struct *blkcg_punt_bio_wq; + +static DEFINE_RAW_SPINLOCK(blkg_stat_lock); + +#define BLKG_DESTROY_BATCH_SIZE 64 + +/* + * Lockless lists for tracking IO stats update + * + * New IO stats are stored in the percpu iostat_cpu within blkcg_gq (blkg). + * There are multiple blkg's (one for each block device) attached to each + * blkcg. The rstat code keeps track of which cpu has IO stats updated, + * but it doesn't know which blkg has the updated stats. If there are many + * block devices in a system, the cost of iterating all the blkg's to flush + * out the IO stats can be high. To reduce such overhead, a set of percpu + * lockless lists (lhead) per blkcg are used to track the set of recently + * updated iostat_cpu's since the last flush. An iostat_cpu will be put + * onto the lockless list on the update side [blk_cgroup_bio_start()] if + * not there yet and then removed when being flushed [blkcg_rstat_flush()]. + * References to blkg are gotten and then put back in the process to + * protect against blkg removal. + * + * Return: 0 if successful or -ENOMEM if allocation fails. + */ +static int init_blkcg_llists(struct blkcg *blkcg) +{ + int cpu; + + blkcg->lhead = alloc_percpu_gfp(struct llist_head, GFP_KERNEL); + if (!blkcg->lhead) + return -ENOMEM; + + for_each_possible_cpu(cpu) + init_llist_head(per_cpu_ptr(blkcg->lhead, cpu)); + return 0; +} + +/** + * blkcg_css - find the current css + * + * Find the css associated with either the kthread or the current task. + * This may return a dying css, so it is up to the caller to use tryget logic + * to confirm it is alive and well. + */ +static struct cgroup_subsys_state *blkcg_css(void) +{ + struct cgroup_subsys_state *css; + + css = kthread_blkcg(); + if (css) + return css; + return task_css(current, io_cgrp_id); +} static bool blkcg_policy_enabled(struct request_queue *q, const struct blkcg_policy *pol) @@ -63,6 +116,37 @@ static bool blkcg_policy_enabled(struct request_queue *q, return pol && test_bit(pol->plid, q->blkcg_pols); } +static void blkg_free_workfn(struct work_struct *work) +{ + struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, + free_work); + struct request_queue *q = blkg->q; + int i; + + /* + * pd_free_fn() can also be called from blkcg_deactivate_policy(), + * in order to make sure pd_free_fn() is called in order, the deletion + * of the list blkg->q_node is delayed to here from blkg_destroy(), and + * blkcg_mutex is used to synchronize blkg_free_workfn() and + * blkcg_deactivate_policy(). + */ + mutex_lock(&q->blkcg_mutex); + for (i = 0; i < BLKCG_MAX_POLS; i++) + if (blkg->pd[i]) + blkcg_policy[i]->pd_free_fn(blkg->pd[i]); + if (blkg->parent) + blkg_put(blkg->parent); + spin_lock_irq(&q->queue_lock); + list_del_init(&blkg->q_node); + spin_unlock_irq(&q->queue_lock); + mutex_unlock(&q->blkcg_mutex); + + blk_put_queue(q); + free_percpu(blkg->iostat_cpu); + percpu_ref_exit(&blkg->refcnt); + kfree(blkg); +} + /** * blkg_free - free a blkg * @blkg: blkg to free @@ -71,34 +155,37 @@ static bool blkcg_policy_enabled(struct request_queue *q, */ static void blkg_free(struct blkcg_gq *blkg) { - int i; - if (!blkg) return; - for (i = 0; i < BLKCG_MAX_POLS; i++) - if (blkg->pd[i]) - blkcg_policy[i]->pd_free_fn(blkg->pd[i]); - - blkg_rwstat_exit(&blkg->stat_ios); - blkg_rwstat_exit(&blkg->stat_bytes); - percpu_ref_exit(&blkg->refcnt); - kfree(blkg); + /* + * Both ->pd_free_fn() and request queue's release handler may + * sleep, so free us by scheduling one work func + */ + INIT_WORK(&blkg->free_work, blkg_free_workfn); + schedule_work(&blkg->free_work); } static void __blkg_release(struct rcu_head *rcu) { struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); + struct blkcg *blkcg = blkg->blkcg; + int cpu; +#ifdef CONFIG_BLK_CGROUP_PUNT_BIO WARN_ON(!bio_list_empty(&blkg->async_bios)); +#endif + /* + * Flush all the non-empty percpu lockless lists before releasing + * us, given these stat belongs to us. + * + * blkg_stat_lock is for serializing blkg stat update + */ + for_each_possible_cpu(cpu) + __blkcg_rstat_flush(blkcg, cpu); /* release the blkcg and parent blkg refs this blkg has been holding */ css_put(&blkg->blkcg->css); - if (blkg->parent) - blkg_put(blkg->parent); - - wb_congested_put(blkg->wb_congested); - blkg_free(blkg); } @@ -117,121 +204,184 @@ static void blkg_release(struct percpu_ref *ref) call_rcu(&blkg->rcu_head, __blkg_release); } +#ifdef CONFIG_BLK_CGROUP_PUNT_BIO +static struct workqueue_struct *blkcg_punt_bio_wq; + static void blkg_async_bio_workfn(struct work_struct *work) { struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, async_bio_work); struct bio_list bios = BIO_EMPTY_LIST; struct bio *bio; + struct blk_plug plug; + bool need_plug = false; /* as long as there are pending bios, @blkg can't go away */ - spin_lock_bh(&blkg->async_bio_lock); + spin_lock(&blkg->async_bio_lock); bio_list_merge(&bios, &blkg->async_bios); bio_list_init(&blkg->async_bios); - spin_unlock_bh(&blkg->async_bio_lock); + spin_unlock(&blkg->async_bio_lock); + /* start plug only when bio_list contains at least 2 bios */ + if (bios.head && bios.head->bi_next) { + need_plug = true; + blk_start_plug(&plug); + } while ((bio = bio_list_pop(&bios))) submit_bio(bio); + if (need_plug) + blk_finish_plug(&plug); +} + +/* + * When a shared kthread issues a bio for a cgroup, doing so synchronously can + * lead to priority inversions as the kthread can be trapped waiting for that + * cgroup. Use this helper instead of submit_bio to punt the actual issuing to + * a dedicated per-blkcg work item to avoid such priority inversions. + */ +void blkcg_punt_bio_submit(struct bio *bio) +{ + struct blkcg_gq *blkg = bio->bi_blkg; + + if (blkg->parent) { + spin_lock(&blkg->async_bio_lock); + bio_list_add(&blkg->async_bios, bio); + spin_unlock(&blkg->async_bio_lock); + queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); + } else { + /* never bounce for the root cgroup */ + submit_bio(bio); + } +} +EXPORT_SYMBOL_GPL(blkcg_punt_bio_submit); + +static int __init blkcg_punt_bio_init(void) +{ + blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", + WQ_MEM_RECLAIM | WQ_FREEZABLE | + WQ_UNBOUND | WQ_SYSFS, 0); + if (!blkcg_punt_bio_wq) + return -ENOMEM; + return 0; +} +subsys_initcall(blkcg_punt_bio_init); +#endif /* CONFIG_BLK_CGROUP_PUNT_BIO */ + +/** + * bio_blkcg_css - return the blkcg CSS associated with a bio + * @bio: target bio + * + * This returns the CSS for the blkcg associated with a bio, or %NULL if not + * associated. Callers are expected to either handle %NULL or know association + * has been done prior to calling this. + */ +struct cgroup_subsys_state *bio_blkcg_css(struct bio *bio) +{ + if (!bio || !bio->bi_blkg) + return NULL; + return &bio->bi_blkg->blkcg->css; +} +EXPORT_SYMBOL_GPL(bio_blkcg_css); + +/** + * blkcg_parent - get the parent of a blkcg + * @blkcg: blkcg of interest + * + * Return the parent blkcg of @blkcg. Can be called anytime. + */ +static inline struct blkcg *blkcg_parent(struct blkcg *blkcg) +{ + return css_to_blkcg(blkcg->css.parent); } /** * blkg_alloc - allocate a blkg * @blkcg: block cgroup the new blkg is associated with - * @q: request_queue the new blkg is associated with + * @disk: gendisk the new blkg is associated with * @gfp_mask: allocation mask to use * - * Allocate a new blkg assocating @blkcg and @q. + * Allocate a new blkg associating @blkcg and @disk. */ -static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, +static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, gfp_t gfp_mask) { struct blkcg_gq *blkg; - int i; + int i, cpu; /* alloc and init base part */ - blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); + blkg = kzalloc_node(sizeof(*blkg), gfp_mask, disk->queue->node); if (!blkg) return NULL; - if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) - goto err_free; - - if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) || - blkg_rwstat_init(&blkg->stat_ios, gfp_mask)) - goto err_free; - - blkg->q = q; + goto out_free_blkg; + blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); + if (!blkg->iostat_cpu) + goto out_exit_refcnt; + if (!blk_get_queue(disk->queue)) + goto out_free_iostat; + + blkg->q = disk->queue; INIT_LIST_HEAD(&blkg->q_node); + blkg->blkcg = blkcg; +#ifdef CONFIG_BLK_CGROUP_PUNT_BIO spin_lock_init(&blkg->async_bio_lock); bio_list_init(&blkg->async_bios); INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn); - blkg->blkcg = blkcg; +#endif + + u64_stats_init(&blkg->iostat.sync); + for_each_possible_cpu(cpu) { + u64_stats_init(&per_cpu_ptr(blkg->iostat_cpu, cpu)->sync); + per_cpu_ptr(blkg->iostat_cpu, cpu)->blkg = blkg; + } for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; struct blkg_policy_data *pd; - if (!blkcg_policy_enabled(q, pol)) + if (!blkcg_policy_enabled(disk->queue, pol)) continue; /* alloc per-policy data and attach it to blkg */ - pd = pol->pd_alloc_fn(gfp_mask, q, blkcg); + pd = pol->pd_alloc_fn(disk, blkcg, gfp_mask); if (!pd) - goto err_free; - + goto out_free_pds; blkg->pd[i] = pd; pd->blkg = blkg; pd->plid = i; + pd->online = false; } return blkg; -err_free: - blkg_free(blkg); - return NULL; -} - -struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, - struct request_queue *q, bool update_hint) -{ - struct blkcg_gq *blkg; - - /* - * Hint didn't match. Look up from the radix tree. Note that the - * hint can only be updated under queue_lock as otherwise @blkg - * could have already been removed from blkg_tree. The caller is - * responsible for grabbing queue_lock if @update_hint. - */ - blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); - if (blkg && blkg->q == q) { - if (update_hint) { - lockdep_assert_held(&q->queue_lock); - rcu_assign_pointer(blkcg->blkg_hint, blkg); - } - return blkg; - } - +out_free_pds: + while (--i >= 0) + if (blkg->pd[i]) + blkcg_policy[i]->pd_free_fn(blkg->pd[i]); + blk_put_queue(disk->queue); +out_free_iostat: + free_percpu(blkg->iostat_cpu); +out_exit_refcnt: + percpu_ref_exit(&blkg->refcnt); +out_free_blkg: + kfree(blkg); return NULL; } -EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); /* * If @new_blkg is %NULL, this function tries to allocate a new one as * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. */ -static struct blkcg_gq *blkg_create(struct blkcg *blkcg, - struct request_queue *q, +static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk, struct blkcg_gq *new_blkg) { struct blkcg_gq *blkg; - struct bdi_writeback_congested *wb_congested; int i, ret; - WARN_ON_ONCE(!rcu_read_lock_held()); - lockdep_assert_held(&q->queue_lock); + lockdep_assert_held(&disk->queue->queue_lock); /* request_queue is dying, do not create/recreate a blkg */ - if (blk_queue_dying(q)) { + if (blk_queue_dying(disk->queue)) { ret = -ENODEV; goto err_free_blkg; } @@ -242,31 +392,22 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, goto err_free_blkg; } - wb_congested = wb_congested_get_create(q->backing_dev_info, - blkcg->css.id, - GFP_NOWAIT | __GFP_NOWARN); - if (!wb_congested) { - ret = -ENOMEM; - goto err_put_css; - } - /* allocate */ if (!new_blkg) { - new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); + new_blkg = blkg_alloc(blkcg, disk, GFP_NOWAIT | __GFP_NOWARN); if (unlikely(!new_blkg)) { ret = -ENOMEM; - goto err_put_congested; + goto err_put_css; } } blkg = new_blkg; - blkg->wb_congested = wb_congested; /* link parent */ if (blkcg_parent(blkcg)) { - blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); + blkg->parent = blkg_lookup(blkcg_parent(blkcg), disk->queue); if (WARN_ON_ONCE(!blkg->parent)) { ret = -ENODEV; - goto err_put_congested; + goto err_put_css; } blkg_get(blkg->parent); } @@ -281,16 +422,19 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, /* insert */ spin_lock(&blkcg->lock); - ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); + ret = radix_tree_insert(&blkcg->blkg_tree, disk->queue->id, blkg); if (likely(!ret)) { hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); - list_add(&blkg->q_node, &q->blkg_list); + list_add(&blkg->q_node, &disk->queue->blkg_list); for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; - if (blkg->pd[i] && pol->pd_online_fn) - pol->pd_online_fn(blkg->pd[i]); + if (blkg->pd[i]) { + if (pol->pd_online_fn) + pol->pd_online_fn(blkg->pd[i]); + blkg->pd[i]->online = true; + } } } blkg->online = true; @@ -303,40 +447,49 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, blkg_put(blkg); return ERR_PTR(ret); -err_put_congested: - wb_congested_put(wb_congested); err_put_css: css_put(&blkcg->css); err_free_blkg: - blkg_free(new_blkg); + if (new_blkg) + blkg_free(new_blkg); return ERR_PTR(ret); } /** - * __blkg_lookup_create - lookup blkg, try to create one if not there + * blkg_lookup_create - lookup blkg, try to create one if not there * @blkcg: blkcg of interest - * @q: request_queue of interest + * @disk: gendisk of interest * - * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to + * Lookup blkg for the @blkcg - @disk pair. If it doesn't exist, try to * create one. blkg creation is performed recursively from blkcg_root such * that all non-root blkg's have access to the parent blkg. This function - * should be called under RCU read lock and @q->queue_lock. + * should be called under RCU read lock and takes @disk->queue->queue_lock. * * Returns the blkg or the closest blkg if blkg_create() fails as it walks * down from root. */ -struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, - struct request_queue *q) +static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, + struct gendisk *disk) { + struct request_queue *q = disk->queue; struct blkcg_gq *blkg; + unsigned long flags; WARN_ON_ONCE(!rcu_read_lock_held()); - lockdep_assert_held(&q->queue_lock); - blkg = __blkg_lookup(blkcg, q, true); + blkg = blkg_lookup(blkcg, q); if (blkg) return blkg; + spin_lock_irqsave(&q->queue_lock, flags); + blkg = blkg_lookup(blkcg, q); + if (blkg) { + if (blkcg != &blkcg_root && + blkg != rcu_dereference(blkcg->blkg_hint)) + rcu_assign_pointer(blkcg->blkg_hint, blkg); + goto found; + } + /* * Create blkgs walking down from blkcg_root to @blkcg, so that all * non-root blkgs have access to their parents. Returns the closest @@ -348,7 +501,7 @@ struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, struct blkcg_gq *ret_blkg = q->root_blkg; while (parent) { - blkg = __blkg_lookup(parent, q, false); + blkg = blkg_lookup(parent, q); if (blkg) { /* remember closest blkg */ ret_blkg = blkg; @@ -358,67 +511,50 @@ struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, parent = blkcg_parent(parent); } - blkg = blkg_create(pos, q, NULL); - if (IS_ERR(blkg)) - return ret_blkg; + blkg = blkg_create(pos, disk, NULL); + if (IS_ERR(blkg)) { + blkg = ret_blkg; + break; + } if (pos == blkcg) - return blkg; - } -} - -/** - * blkg_lookup_create - find or create a blkg - * @blkcg: target block cgroup - * @q: target request_queue - * - * This looks up or creates the blkg representing the unique pair - * of the blkcg and the request_queue. - */ -struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, - struct request_queue *q) -{ - struct blkcg_gq *blkg = blkg_lookup(blkcg, q); - - if (unlikely(!blkg)) { - unsigned long flags; - - spin_lock_irqsave(&q->queue_lock, flags); - blkg = __blkg_lookup_create(blkcg, q); - spin_unlock_irqrestore(&q->queue_lock, flags); + break; } +found: + spin_unlock_irqrestore(&q->queue_lock, flags); return blkg; } static void blkg_destroy(struct blkcg_gq *blkg) { struct blkcg *blkcg = blkg->blkcg; - struct blkcg_gq *parent = blkg->parent; int i; lockdep_assert_held(&blkg->q->queue_lock); 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)); + /* + * blkg stays on the queue list until blkg_free_workfn(), see details in + * blkg_free_workfn(), hence this function can be called from + * blkcg_destroy_blkgs() first and again from blkg_destroy_all() before + * blkg_free_workfn(). + */ + if (hlist_unhashed(&blkg->blkcg_node)) + return; for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; - if (blkg->pd[i] && pol->pd_offline_fn) - pol->pd_offline_fn(blkg->pd[i]); - } - - if (parent) { - blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes); - blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios); + if (blkg->pd[i] && blkg->pd[i]->online) { + blkg->pd[i]->online = false; + if (pol->pd_offline_fn) + pol->pd_offline_fn(blkg->pd[i]); + } } blkg->online = false; radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); - list_del_init(&blkg->q_node); hlist_del_init_rcu(&blkg->blkcg_node); /* @@ -436,23 +572,47 @@ static void blkg_destroy(struct blkcg_gq *blkg) percpu_ref_kill(&blkg->refcnt); } -/** - * blkg_destroy_all - destroy all blkgs associated with a request_queue - * @q: request_queue of interest - * - * Destroy all blkgs associated with @q. - */ -static void blkg_destroy_all(struct request_queue *q) +static void blkg_destroy_all(struct gendisk *disk) { - struct blkcg_gq *blkg, *n; + struct request_queue *q = disk->queue; + struct blkcg_gq *blkg; + int count = BLKG_DESTROY_BATCH_SIZE; + int i; +restart: spin_lock_irq(&q->queue_lock); - list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { + list_for_each_entry(blkg, &q->blkg_list, q_node) { struct blkcg *blkcg = blkg->blkcg; + if (hlist_unhashed(&blkg->blkcg_node)) + continue; + spin_lock(&blkcg->lock); blkg_destroy(blkg); spin_unlock(&blkcg->lock); + + /* + * in order to avoid holding the spin lock for too long, release + * it when a batch of blkgs are destroyed. + */ + if (!(--count)) { + count = BLKG_DESTROY_BATCH_SIZE; + spin_unlock_irq(&q->queue_lock); + cond_resched(); + goto restart; + } + } + + /* + * Mark policy deactivated since policy offline has been done, and + * the free is scheduled, so future blkcg_deactivate_policy() can + * be bypassed + */ + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; + + if (pol) + __clear_bit(pol->plid, q->blkcg_pols); } q->root_blkg = NULL; @@ -464,7 +624,7 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css, { struct blkcg *blkcg = css_to_blkcg(css); struct blkcg_gq *blkg; - int i; + int i, cpu; mutex_lock(&blkcg_pol_mutex); spin_lock_irq(&blkcg->lock); @@ -475,8 +635,17 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css, * anyway. If you get hit by a race, retry. */ hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { - blkg_rwstat_reset(&blkg->stat_bytes); - blkg_rwstat_reset(&blkg->stat_ios); + for_each_possible_cpu(cpu) { + struct blkg_iostat_set *bis = + per_cpu_ptr(blkg->iostat_cpu, cpu); + memset(bis, 0, sizeof(*bis)); + + /* Re-initialize the cleared blkg_iostat_set */ + u64_stats_init(&bis->sync); + bis->blkg = blkg; + } + memset(&blkg->iostat, 0, sizeof(blkg->iostat)); + u64_stats_init(&blkg->iostat.sync); for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; @@ -493,10 +662,9 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css, const char *blkg_dev_name(struct blkcg_gq *blkg) { - /* some drivers (floppy) instantiate a queue w/o disk registered */ - if (blkg->q->backing_dev_info->dev) - return dev_name(blkg->q->backing_dev_info->dev); - return NULL; + if (!blkg->q->disk) + return NULL; + return bdi_dev_name(blkg->q->disk->bdi); } /** @@ -546,7 +714,7 @@ EXPORT_SYMBOL_GPL(blkcg_print_blkgs); * @pd: policy private data of interest * @v: value to print * - * Print @v to @sf for the device assocaited with @pd. + * Print @v to @sf for the device associated with @pd. */ u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) { @@ -561,272 +729,118 @@ u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) EXPORT_SYMBOL_GPL(__blkg_prfill_u64); /** - * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat - * @sf: seq_file to print to - * @pd: policy private data of interest - * @rwstat: rwstat to print - * - * Print @rwstat to @sf for the device assocaited with @pd. - */ -u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, - const struct blkg_rwstat_sample *rwstat) -{ - static const char *rwstr[] = { - [BLKG_RWSTAT_READ] = "Read", - [BLKG_RWSTAT_WRITE] = "Write", - [BLKG_RWSTAT_SYNC] = "Sync", - [BLKG_RWSTAT_ASYNC] = "Async", - [BLKG_RWSTAT_DISCARD] = "Discard", - }; - const char *dname = blkg_dev_name(pd->blkg); - u64 v; - int i; - - if (!dname) - return 0; - - for (i = 0; i < BLKG_RWSTAT_NR; i++) - seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], - rwstat->cnt[i]); - - v = rwstat->cnt[BLKG_RWSTAT_READ] + - rwstat->cnt[BLKG_RWSTAT_WRITE] + - rwstat->cnt[BLKG_RWSTAT_DISCARD]; - seq_printf(sf, "%s Total %llu\n", dname, v); - return v; -} -EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); - -/** - * blkg_prfill_rwstat - prfill callback for blkg_rwstat - * @sf: seq_file to print to - * @pd: policy private data of interest - * @off: offset to the blkg_rwstat in @pd - * - * prfill callback for printing a blkg_rwstat. - */ -u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, - int off) -{ - struct blkg_rwstat_sample rwstat = { }; - - blkg_rwstat_read((void *)pd + off, &rwstat); - return __blkg_prfill_rwstat(sf, pd, &rwstat); -} -EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); - -static u64 blkg_prfill_rwstat_field(struct seq_file *sf, - struct blkg_policy_data *pd, int off) -{ - struct blkg_rwstat_sample rwstat = { }; - - blkg_rwstat_read((void *)pd->blkg + off, &rwstat); - return __blkg_prfill_rwstat(sf, pd, &rwstat); -} - -/** - * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes - * @sf: seq_file to print to - * @v: unused - * - * To be used as cftype->seq_show to print blkg->stat_bytes. - * cftype->private must be set to the blkcg_policy. - */ -int blkg_print_stat_bytes(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, - offsetof(struct blkcg_gq, stat_bytes), true); - return 0; -} -EXPORT_SYMBOL_GPL(blkg_print_stat_bytes); - -/** - * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios - * @sf: seq_file to print to - * @v: unused - * - * To be used as cftype->seq_show to print blkg->stat_ios. cftype->private - * must be set to the blkcg_policy. - */ -int blkg_print_stat_ios(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, - offsetof(struct blkcg_gq, stat_ios), true); - return 0; -} -EXPORT_SYMBOL_GPL(blkg_print_stat_ios); - -static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf, - struct blkg_policy_data *pd, - int off) -{ - struct blkg_rwstat_sample rwstat; - - blkg_rwstat_recursive_sum(pd->blkg, NULL, off, &rwstat); - return __blkg_prfill_rwstat(sf, pd, &rwstat); -} - -/** - * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes - * @sf: seq_file to print to - * @v: unused - */ -int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - blkg_prfill_rwstat_field_recursive, - (void *)seq_cft(sf)->private, - offsetof(struct blkcg_gq, stat_bytes), true); - return 0; -} -EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive); - -/** - * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios - * @sf: seq_file to print to - * @v: unused - */ -int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - blkg_prfill_rwstat_field_recursive, - (void *)seq_cft(sf)->private, - offsetof(struct blkcg_gq, stat_ios), true); - return 0; -} -EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive); - -/** - * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat - * @blkg: blkg of interest - * @pol: blkcg_policy which contains the blkg_rwstat - * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg - * @sum: blkg_rwstat_sample structure containing the results - * - * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its - * online descendants and their aux counts. The caller must be holding the - * queue lock for online tests. + * blkg_conf_init - initialize a blkg_conf_ctx + * @ctx: blkg_conf_ctx to initialize + * @input: input string * - * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it - * is at @off bytes into @blkg's blkg_policy_data of the policy. + * Initialize @ctx which can be used to parse blkg config input string @input. + * Once initialized, @ctx can be used with blkg_conf_open_bdev() and + * blkg_conf_prep(), and must be cleaned up with blkg_conf_exit(). */ -void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, - int off, struct blkg_rwstat_sample *sum) -{ - struct blkcg_gq *pos_blkg; - struct cgroup_subsys_state *pos_css; - unsigned int i; - - lockdep_assert_held(&blkg->q->queue_lock); - - rcu_read_lock(); - blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { - struct blkg_rwstat *rwstat; - - if (!pos_blkg->online) - continue; - - if (pol) - rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off; - else - rwstat = (void *)pos_blkg + off; - - for (i = 0; i < BLKG_RWSTAT_NR; i++) - sum->cnt[i] = blkg_rwstat_read_counter(rwstat, i); - } - rcu_read_unlock(); -} -EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); - -/* Performs queue bypass and policy enabled checks then looks up blkg. */ -static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, - const struct blkcg_policy *pol, - struct request_queue *q) +void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input) { - WARN_ON_ONCE(!rcu_read_lock_held()); - lockdep_assert_held(&q->queue_lock); - - if (!blkcg_policy_enabled(q, pol)) - return ERR_PTR(-EOPNOTSUPP); - return __blkg_lookup(blkcg, q, true /* update_hint */); + *ctx = (struct blkg_conf_ctx){ .input = input }; } +EXPORT_SYMBOL_GPL(blkg_conf_init); /** - * blkg_conf_prep - parse and prepare for per-blkg config update - * @inputp: input string pointer + * blkg_conf_open_bdev - parse and open bdev for per-blkg config update + * @ctx: blkg_conf_ctx initialized with blkg_conf_init() * - * Parse the device node prefix part, MAJ:MIN, of per-blkg config update - * from @input and get and return the matching gendisk. *@inputp is - * updated to point past the device node prefix. Returns an ERR_PTR() - * value on error. + * Parse the device node prefix part, MAJ:MIN, of per-blkg config update from + * @ctx->input and get and store the matching bdev in @ctx->bdev. @ctx->body is + * set to point past the device node prefix. * - * Use this function iff blkg_conf_prep() can't be used for some reason. + * This function may be called multiple times on @ctx and the extra calls become + * NOOPs. blkg_conf_prep() implicitly calls this function. Use this function + * explicitly if bdev access is needed without resolving the blkcg / policy part + * of @ctx->input. Returns -errno on error. */ -struct gendisk *blkcg_conf_get_disk(char **inputp) +int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx) { - char *input = *inputp; + char *input = ctx->input; unsigned int major, minor; - struct gendisk *disk; - int key_len, part; + struct block_device *bdev; + int key_len; + + if (ctx->bdev) + return 0; if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) - return ERR_PTR(-EINVAL); + return -EINVAL; input += key_len; if (!isspace(*input)) - return ERR_PTR(-EINVAL); + return -EINVAL; input = skip_spaces(input); - disk = get_gendisk(MKDEV(major, minor), &part); - if (!disk) - return ERR_PTR(-ENODEV); - if (part) { - put_disk_and_module(disk); - return ERR_PTR(-ENODEV); + bdev = blkdev_get_no_open(MKDEV(major, minor)); + if (!bdev) + return -ENODEV; + if (bdev_is_partition(bdev)) { + blkdev_put_no_open(bdev); + return -ENODEV; } - *inputp = input; - return disk; + mutex_lock(&bdev->bd_queue->rq_qos_mutex); + if (!disk_live(bdev->bd_disk)) { + blkdev_put_no_open(bdev); + mutex_unlock(&bdev->bd_queue->rq_qos_mutex); + return -ENODEV; + } + + ctx->body = input; + ctx->bdev = bdev; + return 0; } /** * blkg_conf_prep - parse and prepare for per-blkg config update * @blkcg: target block cgroup * @pol: target policy - * @input: input string - * @ctx: blkg_conf_ctx to be filled + * @ctx: blkg_conf_ctx initialized with blkg_conf_init() * - * Parse per-blkg config update from @input and initialize @ctx with the - * result. @ctx->blkg points to the blkg to be updated and @ctx->body the - * part of @input following MAJ:MIN. This function returns with RCU read - * lock and queue lock held and must be paired with blkg_conf_finish(). + * Parse per-blkg config update from @ctx->input and initialize @ctx + * accordingly. On success, @ctx->body points to the part of @ctx->input + * following MAJ:MIN, @ctx->bdev points to the target block device and + * @ctx->blkg to the blkg being configured. + * + * blkg_conf_open_bdev() may be called on @ctx beforehand. On success, this + * function returns with queue lock held and must be followed by + * blkg_conf_exit(). */ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, - char *input, struct blkg_conf_ctx *ctx) - __acquires(rcu) __acquires(&disk->queue->queue_lock) + struct blkg_conf_ctx *ctx) + __acquires(&bdev->bd_queue->queue_lock) { struct gendisk *disk; struct request_queue *q; struct blkcg_gq *blkg; int ret; - disk = blkcg_conf_get_disk(&input); - if (IS_ERR(disk)) - return PTR_ERR(disk); + ret = blkg_conf_open_bdev(ctx); + if (ret) + return ret; + disk = ctx->bdev->bd_disk; q = disk->queue; - rcu_read_lock(); + /* + * blkcg_deactivate_policy() requires queue to be frozen, we can grab + * q_usage_counter to prevent concurrent with blkcg_deactivate_policy(). + */ + ret = blk_queue_enter(q, 0); + if (ret) + goto fail; + spin_lock_irq(&q->queue_lock); - blkg = blkg_lookup_check(blkcg, pol, q); - if (IS_ERR(blkg)) { - ret = PTR_ERR(blkg); + if (!blkcg_policy_enabled(q, pol)) { + ret = -EOPNOTSUPP; goto fail_unlock; } + blkg = blkg_lookup(blkcg, q); if (blkg) goto success; @@ -840,54 +854,62 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, struct blkcg_gq *new_blkg; parent = blkcg_parent(blkcg); - while (parent && !__blkg_lookup(parent, q, false)) { + while (parent && !blkg_lookup(parent, q)) { pos = parent; parent = blkcg_parent(parent); } /* Drop locks to do new blkg allocation with GFP_KERNEL. */ spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); - new_blkg = blkg_alloc(pos, q, GFP_KERNEL); + new_blkg = blkg_alloc(pos, disk, GFP_KERNEL); if (unlikely(!new_blkg)) { ret = -ENOMEM; - goto fail; + goto fail_exit_queue; + } + + if (radix_tree_preload(GFP_KERNEL)) { + blkg_free(new_blkg); + ret = -ENOMEM; + goto fail_exit_queue; } - rcu_read_lock(); spin_lock_irq(&q->queue_lock); - blkg = blkg_lookup_check(pos, pol, q); - if (IS_ERR(blkg)) { - ret = PTR_ERR(blkg); - goto fail_unlock; + if (!blkcg_policy_enabled(q, pol)) { + blkg_free(new_blkg); + ret = -EOPNOTSUPP; + goto fail_preloaded; } + blkg = blkg_lookup(pos, q); if (blkg) { blkg_free(new_blkg); } else { - blkg = blkg_create(pos, q, new_blkg); + blkg = blkg_create(pos, disk, new_blkg); if (IS_ERR(blkg)) { ret = PTR_ERR(blkg); - goto fail_unlock; + goto fail_preloaded; } } + radix_tree_preload_end(); + if (pos == blkcg) goto success; } success: - ctx->disk = disk; + blk_queue_exit(q); ctx->blkg = blkg; - ctx->body = input; return 0; +fail_preloaded: + radix_tree_preload_end(); fail_unlock: spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); +fail_exit_queue: + blk_queue_exit(q); fail: - put_disk_and_module(disk); /* * If queue was bypassing, we should retry. Do so after a * short msleep(). It isn't strictly necessary but queue @@ -903,107 +925,251 @@ fail: EXPORT_SYMBOL_GPL(blkg_conf_prep); /** - * blkg_conf_finish - finish up per-blkg config update - * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() + * blkg_conf_exit - clean up per-blkg config update + * @ctx: blkg_conf_ctx initialized with blkg_conf_init() * - * Finish up after per-blkg config update. This function must be paired - * with blkg_conf_prep(). + * Clean up after per-blkg config update. This function must be called on all + * blkg_conf_ctx's initialized with blkg_conf_init(). */ -void blkg_conf_finish(struct blkg_conf_ctx *ctx) - __releases(&ctx->disk->queue->queue_lock) __releases(rcu) +void blkg_conf_exit(struct blkg_conf_ctx *ctx) + __releases(&ctx->bdev->bd_queue->queue_lock) + __releases(&ctx->bdev->bd_queue->rq_qos_mutex) { - spin_unlock_irq(&ctx->disk->queue->queue_lock); - rcu_read_unlock(); - put_disk_and_module(ctx->disk); + if (ctx->blkg) { + spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock); + ctx->blkg = NULL; + } + + if (ctx->bdev) { + mutex_unlock(&ctx->bdev->bd_queue->rq_qos_mutex); + blkdev_put_no_open(ctx->bdev); + ctx->body = NULL; + ctx->bdev = NULL; + } } -EXPORT_SYMBOL_GPL(blkg_conf_finish); +EXPORT_SYMBOL_GPL(blkg_conf_exit); -static int blkcg_print_stat(struct seq_file *sf, void *v) +static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) { - struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); - struct blkcg_gq *blkg; + int i; + + for (i = 0; i < BLKG_IOSTAT_NR; i++) { + dst->bytes[i] = src->bytes[i]; + dst->ios[i] = src->ios[i]; + } +} + +static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src) +{ + int i; + + for (i = 0; i < BLKG_IOSTAT_NR; i++) { + dst->bytes[i] += src->bytes[i]; + dst->ios[i] += src->ios[i]; + } +} + +static void blkg_iostat_sub(struct blkg_iostat *dst, struct blkg_iostat *src) +{ + int i; + + for (i = 0; i < BLKG_IOSTAT_NR; i++) { + dst->bytes[i] -= src->bytes[i]; + dst->ios[i] -= src->ios[i]; + } +} + +static void blkcg_iostat_update(struct blkcg_gq *blkg, struct blkg_iostat *cur, + struct blkg_iostat *last) +{ + struct blkg_iostat delta; + unsigned long flags; + + /* propagate percpu delta to global */ + flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync); + blkg_iostat_set(&delta, cur); + blkg_iostat_sub(&delta, last); + blkg_iostat_add(&blkg->iostat.cur, &delta); + blkg_iostat_add(last, &delta); + u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); +} + +static void __blkcg_rstat_flush(struct blkcg *blkcg, int cpu) +{ + struct llist_head *lhead = per_cpu_ptr(blkcg->lhead, cpu); + struct llist_node *lnode; + struct blkg_iostat_set *bisc, *next_bisc; + unsigned long flags; rcu_read_lock(); - hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { - const char *dname; - char *buf; - struct blkg_rwstat_sample rwstat; - u64 rbytes, wbytes, rios, wios, dbytes, dios; - size_t size = seq_get_buf(sf, &buf), off = 0; - int i; - bool has_stats = false; + lnode = llist_del_all(lhead); + if (!lnode) + goto out; - spin_lock_irq(&blkg->q->queue_lock); + /* + * For covering concurrent parent blkg update from blkg_release(). + * + * When flushing from cgroup, cgroup_rstat_lock is always held, so + * this lock won't cause contention most of time. + */ + raw_spin_lock_irqsave(&blkg_stat_lock, flags); - if (!blkg->online) - goto skip; + /* + * Iterate only the iostat_cpu's queued in the lockless list. + */ + llist_for_each_entry_safe(bisc, next_bisc, lnode, lnode) { + struct blkcg_gq *blkg = bisc->blkg; + struct blkcg_gq *parent = blkg->parent; + struct blkg_iostat cur; + unsigned int seq; + + WRITE_ONCE(bisc->lqueued, false); + + /* fetch the current per-cpu values */ + do { + seq = u64_stats_fetch_begin(&bisc->sync); + blkg_iostat_set(&cur, &bisc->cur); + } while (u64_stats_fetch_retry(&bisc->sync, seq)); + + blkcg_iostat_update(blkg, &cur, &bisc->last); + + /* propagate global delta to parent (unless that's root) */ + if (parent && parent->parent) + blkcg_iostat_update(parent, &blkg->iostat.cur, + &blkg->iostat.last); + } + raw_spin_unlock_irqrestore(&blkg_stat_lock, flags); +out: + rcu_read_unlock(); +} - dname = blkg_dev_name(blkg); - if (!dname) - goto skip; +static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu) +{ + /* Root-level stats are sourced from system-wide IO stats */ + if (cgroup_parent(css->cgroup)) + __blkcg_rstat_flush(css_to_blkcg(css), cpu); +} - /* - * Hooray string manipulation, count is the size written NOT - * INCLUDING THE \0, so size is now count+1 less than what we - * had before, but we want to start writing the next bit from - * the \0 so we only add count to buf. - */ - off += scnprintf(buf+off, size-off, "%s ", dname); - - blkg_rwstat_recursive_sum(blkg, NULL, - offsetof(struct blkcg_gq, stat_bytes), &rwstat); - rbytes = rwstat.cnt[BLKG_RWSTAT_READ]; - wbytes = rwstat.cnt[BLKG_RWSTAT_WRITE]; - dbytes = rwstat.cnt[BLKG_RWSTAT_DISCARD]; - - blkg_rwstat_recursive_sum(blkg, NULL, - offsetof(struct blkcg_gq, stat_ios), &rwstat); - rios = rwstat.cnt[BLKG_RWSTAT_READ]; - wios = rwstat.cnt[BLKG_RWSTAT_WRITE]; - dios = rwstat.cnt[BLKG_RWSTAT_DISCARD]; - - if (rbytes || wbytes || rios || wios) { - has_stats = true; - off += scnprintf(buf+off, size-off, - "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", - rbytes, wbytes, rios, wios, - dbytes, dios); - } +/* + * We source root cgroup stats from the system-wide stats to avoid + * tracking the same information twice and incurring overhead when no + * cgroups are defined. For that reason, cgroup_rstat_flush in + * blkcg_print_stat does not actually fill out the iostat in the root + * cgroup's blkcg_gq. + * + * However, we would like to re-use the printing code between the root and + * non-root cgroups to the extent possible. For that reason, we simulate + * flushing the root cgroup's stats by explicitly filling in the iostat + * with disk level statistics. + */ +static void blkcg_fill_root_iostats(void) +{ + struct class_dev_iter iter; + struct device *dev; + + class_dev_iter_init(&iter, &block_class, NULL, &disk_type); + while ((dev = class_dev_iter_next(&iter))) { + struct block_device *bdev = dev_to_bdev(dev); + struct blkcg_gq *blkg = bdev->bd_disk->queue->root_blkg; + struct blkg_iostat tmp; + int cpu; + unsigned long flags; - if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) { - has_stats = true; - off += scnprintf(buf+off, size-off, - " use_delay=%d delay_nsec=%llu", - atomic_read(&blkg->use_delay), - (unsigned long long)atomic64_read(&blkg->delay_nsec)); + memset(&tmp, 0, sizeof(tmp)); + for_each_possible_cpu(cpu) { + struct disk_stats *cpu_dkstats; + + cpu_dkstats = per_cpu_ptr(bdev->bd_stats, cpu); + tmp.ios[BLKG_IOSTAT_READ] += + cpu_dkstats->ios[STAT_READ]; + tmp.ios[BLKG_IOSTAT_WRITE] += + cpu_dkstats->ios[STAT_WRITE]; + tmp.ios[BLKG_IOSTAT_DISCARD] += + cpu_dkstats->ios[STAT_DISCARD]; + // convert sectors to bytes + tmp.bytes[BLKG_IOSTAT_READ] += + cpu_dkstats->sectors[STAT_READ] << 9; + tmp.bytes[BLKG_IOSTAT_WRITE] += + cpu_dkstats->sectors[STAT_WRITE] << 9; + tmp.bytes[BLKG_IOSTAT_DISCARD] += + cpu_dkstats->sectors[STAT_DISCARD] << 9; } - for (i = 0; i < BLKCG_MAX_POLS; i++) { - struct blkcg_policy *pol = blkcg_policy[i]; - size_t written; + flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync); + blkg_iostat_set(&blkg->iostat.cur, &tmp); + u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); + } +} - if (!blkg->pd[i] || !pol->pd_stat_fn) - continue; +static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s) +{ + struct blkg_iostat_set *bis = &blkg->iostat; + u64 rbytes, wbytes, rios, wios, dbytes, dios; + const char *dname; + unsigned seq; + int i; - written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off); - if (written) - has_stats = true; - off += written; - } + if (!blkg->online) + return; - if (has_stats) { - if (off < size - 1) { - off += scnprintf(buf+off, size-off, "\n"); - seq_commit(sf, off); - } else { - seq_commit(sf, -1); - } - } - skip: - spin_unlock_irq(&blkg->q->queue_lock); + dname = blkg_dev_name(blkg); + if (!dname) + return; + + seq_printf(s, "%s ", dname); + + do { + seq = u64_stats_fetch_begin(&bis->sync); + + rbytes = bis->cur.bytes[BLKG_IOSTAT_READ]; + wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE]; + dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD]; + rios = bis->cur.ios[BLKG_IOSTAT_READ]; + wios = bis->cur.ios[BLKG_IOSTAT_WRITE]; + dios = bis->cur.ios[BLKG_IOSTAT_DISCARD]; + } while (u64_stats_fetch_retry(&bis->sync, seq)); + + if (rbytes || wbytes || rios || wios) { + seq_printf(s, "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", + rbytes, wbytes, rios, wios, + dbytes, dios); } + if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) { + seq_printf(s, " use_delay=%d delay_nsec=%llu", + atomic_read(&blkg->use_delay), + atomic64_read(&blkg->delay_nsec)); + } + + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; + + if (!blkg->pd[i] || !pol->pd_stat_fn) + continue; + + pol->pd_stat_fn(blkg->pd[i], s); + } + + seq_puts(s, "\n"); +} + +static int blkcg_print_stat(struct seq_file *sf, void *v) +{ + struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); + struct blkcg_gq *blkg; + + if (!seq_css(sf)->parent) + blkcg_fill_root_iostats(); + else + cgroup_rstat_flush(blkcg->css.cgroup); + + rcu_read_lock(); + hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { + spin_lock_irq(&blkg->q->queue_lock); + blkcg_print_one_stat(blkg, sf); + spin_unlock_irq(&blkg->q->queue_lock); + } rcu_read_unlock(); return 0; } @@ -1011,7 +1177,6 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) static struct cftype blkcg_files[] = { { .name = "stat", - .flags = CFTYPE_NOT_ON_ROOT, .seq_show = blkcg_print_stat, }, { } /* terminate */ @@ -1025,6 +1190,13 @@ static struct cftype blkcg_legacy_files[] = { { } /* terminate */ }; +#ifdef CONFIG_CGROUP_WRITEBACK +struct list_head *blkcg_get_cgwb_list(struct cgroup_subsys_state *css) +{ + return &css_to_blkcg(css)->cgwb_list; +} +#endif + /* * blkcg destruction is a three-stage process. * @@ -1047,25 +1219,6 @@ static struct cftype blkcg_legacy_files[] = { */ /** - * blkcg_css_offline - cgroup css_offline callback - * @css: css of interest - * - * This function is called when @css is about to go away. Here the cgwbs are - * offlined first and only once writeback associated with the blkcg has - * finished do we start step 2 (see above). - */ -static void blkcg_css_offline(struct cgroup_subsys_state *css) -{ - struct blkcg *blkcg = css_to_blkcg(css); - - /* this prevents anyone from attaching or migrating to this blkcg */ - wb_blkcg_offline(blkcg); - - /* put the base cgwb reference allowing step 2 to be triggered */ - blkcg_cgwb_put(blkcg); -} - -/** * blkcg_destroy_blkgs - responsible for shooting down blkgs * @blkcg: blkcg of interest * @@ -1076,8 +1229,10 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css) * * This is the blkcg counterpart of ioc_release_fn(). */ -void blkcg_destroy_blkgs(struct blkcg *blkcg) +static void blkcg_destroy_blkgs(struct blkcg *blkcg) { + might_sleep(); + spin_lock_irq(&blkcg->lock); while (!hlist_empty(&blkcg->blkg_list)) { @@ -1085,19 +1240,76 @@ void blkcg_destroy_blkgs(struct blkcg *blkcg) struct blkcg_gq, blkcg_node); struct request_queue *q = blkg->q; - if (spin_trylock(&q->queue_lock)) { - blkg_destroy(blkg); - spin_unlock(&q->queue_lock); - } else { + if (need_resched() || !spin_trylock(&q->queue_lock)) { + /* + * Given that the system can accumulate a huge number + * of blkgs in pathological cases, check to see if we + * need to rescheduling to avoid softlockup. + */ spin_unlock_irq(&blkcg->lock); - cpu_relax(); + cond_resched(); spin_lock_irq(&blkcg->lock); + continue; } + + blkg_destroy(blkg); + spin_unlock(&q->queue_lock); } spin_unlock_irq(&blkcg->lock); } +/** + * blkcg_pin_online - pin online state + * @blkcg_css: blkcg of interest + * + * While pinned, a blkcg is kept online. This is primarily used to + * impedance-match blkg and cgwb lifetimes so that blkg doesn't go offline + * while an associated cgwb is still active. + */ +void blkcg_pin_online(struct cgroup_subsys_state *blkcg_css) +{ + refcount_inc(&css_to_blkcg(blkcg_css)->online_pin); +} + +/** + * blkcg_unpin_online - unpin online state + * @blkcg_css: blkcg of interest + * + * This is primarily used to impedance-match blkg and cgwb lifetimes so + * that blkg doesn't go offline while an associated cgwb is still active. + * When this count goes to zero, all active cgwbs have finished so the + * blkcg can continue destruction by calling blkcg_destroy_blkgs(). + */ +void blkcg_unpin_online(struct cgroup_subsys_state *blkcg_css) +{ + struct blkcg *blkcg = css_to_blkcg(blkcg_css); + + do { + if (!refcount_dec_and_test(&blkcg->online_pin)) + break; + blkcg_destroy_blkgs(blkcg); + blkcg = blkcg_parent(blkcg); + } while (blkcg); +} + +/** + * blkcg_css_offline - cgroup css_offline callback + * @css: css of interest + * + * This function is called when @css is about to go away. Here the cgwbs are + * offlined first and only once writeback associated with the blkcg has + * finished do we start step 2 (see above). + */ +static void blkcg_css_offline(struct cgroup_subsys_state *css) +{ + /* this prevents anyone from attaching or migrating to this blkcg */ + wb_blkcg_offline(css); + + /* put the base online pin allowing step 2 to be triggered */ + blkcg_unpin_online(css); +} + static void blkcg_css_free(struct cgroup_subsys_state *css) { struct blkcg *blkcg = css_to_blkcg(css); @@ -1113,6 +1325,7 @@ static void blkcg_css_free(struct cgroup_subsys_state *css) mutex_unlock(&blkcg_pol_mutex); + free_percpu(blkcg->lhead); kfree(blkcg); } @@ -1120,7 +1333,6 @@ static struct cgroup_subsys_state * blkcg_css_alloc(struct cgroup_subsys_state *parent_css) { struct blkcg *blkcg; - struct cgroup_subsys_state *ret; int i; mutex_lock(&blkcg_pol_mutex); @@ -1129,12 +1341,13 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) blkcg = &blkcg_root; } else { blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); - if (!blkcg) { - ret = ERR_PTR(-ENOMEM); + if (!blkcg) goto unlock; - } } + if (init_blkcg_llists(blkcg)) + goto free_blkcg; + for (i = 0; i < BLKCG_MAX_POLS ; i++) { struct blkcg_policy *pol = blkcg_policy[i]; struct blkcg_policy_data *cpd; @@ -1149,23 +1362,20 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) continue; cpd = pol->cpd_alloc_fn(GFP_KERNEL); - if (!cpd) { - ret = ERR_PTR(-ENOMEM); + if (!cpd) goto free_pd_blkcg; - } + blkcg->cpd[i] = cpd; cpd->blkcg = blkcg; cpd->plid = i; - if (pol->cpd_init_fn) - pol->cpd_init_fn(cpd); } spin_lock_init(&blkcg->lock); + refcount_set(&blkcg->online_pin, 1); INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); INIT_HLIST_HEAD(&blkcg->blkg_list); #ifdef CONFIG_CGROUP_WRITEBACK INIT_LIST_HEAD(&blkcg->cgwb_list); - refcount_set(&blkcg->cgwb_refcnt, 1); #endif list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); @@ -1176,160 +1386,98 @@ free_pd_blkcg: for (i--; i >= 0; i--) if (blkcg->cpd[i]) blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); - + free_percpu(blkcg->lhead); +free_blkcg: if (blkcg != &blkcg_root) kfree(blkcg); unlock: mutex_unlock(&blkcg_pol_mutex); - return ret; + return ERR_PTR(-ENOMEM); } -/** - * 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) +static int blkcg_css_online(struct cgroup_subsys_state *css) +{ + struct blkcg *parent = blkcg_parent(css_to_blkcg(css)); + + /* + * blkcg_pin_online() is used to delay blkcg offline so that blkgs + * don't go offline while cgwbs are still active on them. Pin the + * parent so that offline always happens towards the root. + */ + if (parent) + blkcg_pin_online(&parent->css); + return 0; +} + +int blkcg_init_disk(struct gendisk *disk) { + struct request_queue *q = disk->queue; struct blkcg_gq *new_blkg, *blkg; bool preloaded; int ret; - new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); + INIT_LIST_HEAD(&q->blkg_list); + mutex_init(&q->blkcg_mutex); + + new_blkg = blkg_alloc(&blkcg_root, disk, GFP_KERNEL); if (!new_blkg) return -ENOMEM; preloaded = !radix_tree_preload(GFP_KERNEL); /* Make sure the root blkg exists. */ - rcu_read_lock(); + /* spin_lock_irq can serve as RCU read-side critical section. */ spin_lock_irq(&q->queue_lock); - blkg = blkg_create(&blkcg_root, q, new_blkg); + blkg = blkg_create(&blkcg_root, disk, new_blkg); if (IS_ERR(blkg)) goto err_unlock; q->root_blkg = blkg; spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); if (preloaded) radix_tree_preload_end(); - ret = blk_iolatency_init(q); + ret = blk_ioprio_init(disk); if (ret) goto err_destroy_all; - ret = blk_throtl_init(q); + ret = blk_throtl_init(disk); if (ret) - goto err_destroy_all; + goto err_ioprio_exit; + return 0; +err_ioprio_exit: + blk_ioprio_exit(disk); err_destroy_all: - blkg_destroy_all(q); + blkg_destroy_all(disk); return ret; err_unlock: spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); if (preloaded) radix_tree_preload_end(); return PTR_ERR(blkg); } -/** - * 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); - - /* - * @q could be exiting and already have destroyed all blkgs as - * indicated by NULL root_blkg. If so, don't confuse policies. - */ - if (!q->root_blkg) - return; - - blk_throtl_drain(q); -} - -/** - * blkcg_exit_queue - exit and release blkcg part of request_queue - * @q: request_queue being released - * - * Called from blk_exit_queue(). Responsible for exiting blkcg part. - */ -void blkcg_exit_queue(struct request_queue *q) +void blkcg_exit_disk(struct gendisk *disk) { - blkg_destroy_all(q); - 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 blkcg_can_attach(struct cgroup_taskset *tset) -{ - struct task_struct *task; - struct cgroup_subsys_state *dst_css; - struct io_context *ioc; - int ret = 0; - - /* task_lock() is needed to avoid races with exit_io_context() */ - cgroup_taskset_for_each(task, dst_css, 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 blkcg_bind(struct cgroup_subsys_state *root_css) -{ - int i; - - mutex_lock(&blkcg_pol_mutex); - - for (i = 0; i < BLKCG_MAX_POLS; i++) { - struct blkcg_policy *pol = blkcg_policy[i]; - struct blkcg *blkcg; - - if (!pol || !pol->cpd_bind_fn) - continue; - - list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) - if (blkcg->cpd[pol->plid]) - pol->cpd_bind_fn(blkcg->cpd[pol->plid]); - } - mutex_unlock(&blkcg_pol_mutex); + blkg_destroy_all(disk); + blk_throtl_exit(disk); } static void blkcg_exit(struct task_struct *tsk) { - if (tsk->throttle_queue) - blk_put_queue(tsk->throttle_queue); - tsk->throttle_queue = NULL; + if (tsk->throttle_disk) + put_disk(tsk->throttle_disk); + tsk->throttle_disk = NULL; } struct cgroup_subsys io_cgrp_subsys = { .css_alloc = blkcg_css_alloc, + .css_online = blkcg_css_online, .css_offline = blkcg_css_offline, .css_free = blkcg_css_free, - .can_attach = blkcg_can_attach, - .bind = blkcg_bind, + .css_rstat_flush = blkcg_rstat_flush, .dfl_cftypes = blkcg_files, .legacy_cftypes = blkcg_legacy_files, .legacy_name = "blkio", @@ -1346,14 +1494,14 @@ struct cgroup_subsys io_cgrp_subsys = { EXPORT_SYMBOL_GPL(io_cgrp_subsys); /** - * blkcg_activate_policy - activate a blkcg policy on a request_queue - * @q: request_queue of interest + * blkcg_activate_policy - activate a blkcg policy on a gendisk + * @disk: gendisk of interest * @pol: blkcg policy to activate * - * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through + * Activate @pol on @disk. Requires %GFP_KERNEL context. @disk goes through * bypass mode to populate its blkgs with policy_data for @pol. * - * Activation happens with @q bypassed, so nobody would be accessing blkgs + * Activation happens with @disk bypassed, so nobody would be accessing blkgs * from IO path. Update of each blkg is protected by both queue and blkcg * locks so that holding either lock and testing blkcg_policy_enabled() is * always enough for dereferencing policy data. @@ -1361,9 +1509,9 @@ EXPORT_SYMBOL_GPL(io_cgrp_subsys); * The caller is responsible for synchronizing [de]activations and policy * [un]registerations. Returns 0 on success, -errno on failure. */ -int blkcg_activate_policy(struct request_queue *q, - const struct blkcg_policy *pol) +int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol) { + struct request_queue *q = disk->queue; struct blkg_policy_data *pd_prealloc = NULL; struct blkcg_gq *blkg, *pinned_blkg = NULL; int ret; @@ -1376,7 +1524,7 @@ int blkcg_activate_policy(struct request_queue *q, retry: spin_lock_irq(&q->queue_lock); - /* blkg_list is pushed at the head, reverse walk to allocate parents first */ + /* blkg_list is pushed at the head, reverse walk to initialize parents first */ list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { struct blkg_policy_data *pd; @@ -1388,8 +1536,8 @@ retry: pd = pd_prealloc; pd_prealloc = NULL; } else { - pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q, - blkg->blkcg); + pd = pol->pd_alloc_fn(disk, blkg->blkcg, + GFP_NOWAIT | __GFP_NOWARN); } if (!pd) { @@ -1406,23 +1554,29 @@ retry: if (pd_prealloc) pol->pd_free_fn(pd_prealloc); - pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q, - blkg->blkcg); + pd_prealloc = pol->pd_alloc_fn(disk, blkg->blkcg, + GFP_KERNEL); if (pd_prealloc) goto retry; else goto enomem; } - blkg->pd[pol->plid] = pd; + spin_lock(&blkg->blkcg->lock); + pd->blkg = blkg; pd->plid = pol->plid; - } + blkg->pd[pol->plid] = pd; - /* all allocated, init in the same order */ - if (pol->pd_init_fn) - list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) - pol->pd_init_fn(blkg->pd[pol->plid]); + if (pol->pd_init_fn) + pol->pd_init_fn(pd); + + if (pol->pd_online_fn) + pol->pd_online_fn(pd); + pd->online = true; + + spin_unlock(&blkg->blkcg->lock); + } __set_bit(pol->plid, q->blkcg_pols); ret = 0; @@ -1438,13 +1592,22 @@ out: return ret; enomem: - /* alloc failed, nothing's initialized yet, free everything */ + /* alloc failed, take down everything */ spin_lock_irq(&q->queue_lock); list_for_each_entry(blkg, &q->blkg_list, q_node) { - if (blkg->pd[pol->plid]) { - pol->pd_free_fn(blkg->pd[pol->plid]); + struct blkcg *blkcg = blkg->blkcg; + struct blkg_policy_data *pd; + + spin_lock(&blkcg->lock); + pd = blkg->pd[pol->plid]; + if (pd) { + if (pd->online && pol->pd_offline_fn) + pol->pd_offline_fn(pd); + pd->online = false; + pol->pd_free_fn(pd); blkg->pd[pol->plid] = NULL; } + spin_unlock(&blkcg->lock); } spin_unlock_irq(&q->queue_lock); ret = -ENOMEM; @@ -1453,16 +1616,17 @@ enomem: EXPORT_SYMBOL_GPL(blkcg_activate_policy); /** - * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue - * @q: request_queue of interest + * blkcg_deactivate_policy - deactivate a blkcg policy on a gendisk + * @disk: gendisk of interest * @pol: blkcg policy to deactivate * - * Deactivate @pol on @q. Follows the same synchronization rules as + * Deactivate @pol on @disk. Follows the same synchronization rules as * blkcg_activate_policy(). */ -void blkcg_deactivate_policy(struct request_queue *q, +void blkcg_deactivate_policy(struct gendisk *disk, const struct blkcg_policy *pol) { + struct request_queue *q = disk->queue; struct blkcg_gq *blkg; if (!blkcg_policy_enabled(q, pol)) @@ -1471,26 +1635,44 @@ void blkcg_deactivate_policy(struct request_queue *q, if (queue_is_mq(q)) blk_mq_freeze_queue(q); + mutex_lock(&q->blkcg_mutex); spin_lock_irq(&q->queue_lock); __clear_bit(pol->plid, q->blkcg_pols); list_for_each_entry(blkg, &q->blkg_list, q_node) { + struct blkcg *blkcg = blkg->blkcg; + + spin_lock(&blkcg->lock); if (blkg->pd[pol->plid]) { - if (pol->pd_offline_fn) + if (blkg->pd[pol->plid]->online && pol->pd_offline_fn) pol->pd_offline_fn(blkg->pd[pol->plid]); pol->pd_free_fn(blkg->pd[pol->plid]); blkg->pd[pol->plid] = NULL; } + spin_unlock(&blkcg->lock); } spin_unlock_irq(&q->queue_lock); + mutex_unlock(&q->blkcg_mutex); if (queue_is_mq(q)) blk_mq_unfreeze_queue(q); } EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); +static void blkcg_free_all_cpd(struct blkcg_policy *pol) +{ + struct blkcg *blkcg; + + list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { + if (blkcg->cpd[pol->plid]) { + pol->cpd_free_fn(blkcg->cpd[pol->plid]); + blkcg->cpd[pol->plid] = NULL; + } + } +} + /** * blkcg_policy_register - register a blkcg policy * @pol: blkcg policy to register @@ -1537,8 +1719,6 @@ int blkcg_policy_register(struct blkcg_policy *pol) blkcg->cpd[pol->plid] = cpd; cpd->blkcg = blkcg; cpd->plid = pol->plid; - if (pol->cpd_init_fn) - pol->cpd_init_fn(cpd); } } @@ -1555,14 +1735,9 @@ int blkcg_policy_register(struct blkcg_policy *pol) return 0; err_free_cpds: - if (pol->cpd_free_fn) { - list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { - if (blkcg->cpd[pol->plid]) { - pol->cpd_free_fn(blkcg->cpd[pol->plid]); - blkcg->cpd[pol->plid] = NULL; - } - } - } + if (pol->cpd_free_fn) + blkcg_free_all_cpd(pol); + blkcg_policy[pol->plid] = NULL; err_unlock: mutex_unlock(&blkcg_pol_mutex); @@ -1579,8 +1754,6 @@ EXPORT_SYMBOL_GPL(blkcg_policy_register); */ void blkcg_policy_unregister(struct blkcg_policy *pol) { - struct blkcg *blkcg; - mutex_lock(&blkcg_pol_register_mutex); if (WARN_ON(blkcg_policy[pol->plid] != pol)) @@ -1595,14 +1768,9 @@ void blkcg_policy_unregister(struct blkcg_policy *pol) /* remove cpds and unregister */ mutex_lock(&blkcg_pol_mutex); - if (pol->cpd_free_fn) { - list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { - if (blkcg->cpd[pol->plid]) { - pol->cpd_free_fn(blkcg->cpd[pol->plid]); - blkcg->cpd[pol->plid] = NULL; - } - } - } + if (pol->cpd_free_fn) + blkcg_free_all_cpd(pol); + blkcg_policy[pol->plid] = NULL; mutex_unlock(&blkcg_pol_mutex); @@ -1611,25 +1779,6 @@ out_unlock: } EXPORT_SYMBOL_GPL(blkcg_policy_unregister); -bool __blkcg_punt_bio_submit(struct bio *bio) -{ - struct blkcg_gq *blkg = bio->bi_blkg; - - /* consume the flag first */ - bio->bi_opf &= ~REQ_CGROUP_PUNT; - - /* never bounce for the root cgroup */ - if (!blkg->parent) - return false; - - spin_lock_bh(&blkg->async_bio_lock); - bio_list_add(&blkg->async_bios, bio); - spin_unlock_bh(&blkg->async_bio_lock); - - queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); - return true; -} - /* * Scale the accumulated delay based on how long it has been since we updated * the delay. We only call this when we are adding delay, in case it's been a @@ -1640,6 +1789,10 @@ static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) { u64 old = atomic64_read(&blkg->delay_start); + /* negative use_delay means no scaling, see blkcg_set_delay() */ + if (atomic_read(&blkg->use_delay) < 0) + return; + /* * We only want to scale down every second. The idea here is that we * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain @@ -1654,7 +1807,7 @@ static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) * everybody is happy with their IO latencies. */ if (time_before64(old + NSEC_PER_SEC, now) && - atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { + atomic64_try_cmpxchg(&blkg->delay_start, &old, now)) { u64 cur = atomic64_read(&blkg->delay_nsec); u64 sub = min_t(u64, blkg->last_delay, now - old); int cur_use = atomic_read(&blkg->use_delay); @@ -1692,16 +1845,24 @@ static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) { unsigned long pflags; + bool clamp; u64 now = ktime_to_ns(ktime_get()); u64 exp; u64 delay_nsec = 0; int tok; while (blkg->parent) { - if (atomic_read(&blkg->use_delay)) { + int use_delay = atomic_read(&blkg->use_delay); + + if (use_delay) { + u64 this_delay; + blkcg_scale_delay(blkg, now); - delay_nsec = max_t(u64, delay_nsec, - atomic64_read(&blkg->delay_nsec)); + this_delay = atomic64_read(&blkg->delay_nsec); + if (this_delay > delay_nsec) { + delay_nsec = this_delay; + clamp = use_delay > 0; + } } blkg = blkg->parent; } @@ -1713,10 +1874,13 @@ static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) * Let's not sleep for all eternity if we've amassed a huge delay. * Swapping or metadata IO can accumulate 10's of seconds worth of * delay, and we want userspace to be able to do _something_ so cap the - * delays at 1 second. If there's 10's of seconds worth of delay then - * the tasks will be delayed for 1 second for every syscall. + * delays at 0.25s. If there's 10's of seconds worth of delay then the + * tasks will be delayed for 0.25 second for every syscall. If + * blkcg_set_delay() was used as indicated by negative use_delay, the + * caller is responsible for regulating the range. */ - delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); + if (clamp) + delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); if (use_memdelay) psi_memstall_enter(&pflags); @@ -1739,35 +1903,29 @@ static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) * * This is only called if we've been marked with set_notify_resume(). Obviously * we can be set_notify_resume() for reasons other than blkcg throttling, so we - * check to see if current->throttle_queue is set and if not this doesn't do + * check to see if current->throttle_disk is set and if not this doesn't do * anything. This should only ever be called by the resume code, it's not meant * to be called by people willy-nilly as it will actually do the work to * throttle the task if it is setup for throttling. */ void blkcg_maybe_throttle_current(void) { - struct request_queue *q = current->throttle_queue; - struct cgroup_subsys_state *css; + struct gendisk *disk = current->throttle_disk; struct blkcg *blkcg; struct blkcg_gq *blkg; bool use_memdelay = current->use_memdelay; - if (!q) + if (!disk) return; - current->throttle_queue = NULL; + current->throttle_disk = NULL; current->use_memdelay = false; rcu_read_lock(); - css = kthread_blkcg(); - if (css) - blkcg = css_to_blkcg(css); - else - blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); - + blkcg = css_to_blkcg(blkcg_css()); if (!blkcg) goto out; - blkg = blkg_lookup(blkcg, q); + blkg = blkg_lookup(blkcg, disk->queue); if (!blkg) goto out; if (!blkg_tryget(blkg)) @@ -1776,22 +1934,21 @@ void blkcg_maybe_throttle_current(void) blkcg_maybe_throttle_blkg(blkg, use_memdelay); blkg_put(blkg); - blk_put_queue(q); + put_disk(disk); return; out: rcu_read_unlock(); - blk_put_queue(q); } /** * blkcg_schedule_throttle - this task needs to check for throttling - * @q: the request queue IO was submitted on + * @disk: disk to throttle * @use_memdelay: do we charge this to memory delay for PSI * * This is called by the IO controller when we know there's delay accumulated * for the blkg for this task. We do not pass the blkg because there are places * we call this that may not have that information, the swapping code for - * instance will only have a request_queue at that point. This set's the + * instance will only have a block_device at that point. This set's the * notify_resume for the task to check and see if it requires throttling before * returning to user space. * @@ -1800,17 +1957,21 @@ out: * throttle once. If the task needs to be throttled again it'll need to be * re-set at the next time we see the task. */ -void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) +void blkcg_schedule_throttle(struct gendisk *disk, bool use_memdelay) { if (unlikely(current->flags & PF_KTHREAD)) return; - if (!blk_get_queue(q)) - return; + if (current->throttle_disk != disk) { + if (test_bit(GD_DEAD, &disk->state)) + return; + get_device(disk_to_dev(disk)); + + if (current->throttle_disk) + put_disk(current->throttle_disk); + current->throttle_disk = disk; + } - if (current->throttle_queue) - blk_put_queue(current->throttle_queue); - current->throttle_queue = q; if (use_memdelay) current->use_memdelay = use_memdelay; set_notify_resume(current); @@ -1827,20 +1988,178 @@ void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) */ void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) { + if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) + return; blkcg_scale_delay(blkg, now); atomic64_add(delta, &blkg->delay_nsec); } -static int __init blkcg_init(void) +/** + * blkg_tryget_closest - try and get a blkg ref on the closet blkg + * @bio: target bio + * @css: target css + * + * As the failure mode here is to walk up the blkg tree, this ensure that the + * blkg->parent pointers are always valid. This returns the blkg that it ended + * up taking a reference on or %NULL if no reference was taken. + */ +static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio, + struct cgroup_subsys_state *css) { - blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", - WQ_MEM_RECLAIM | WQ_FREEZABLE | - WQ_UNBOUND | WQ_SYSFS, 0); - if (!blkcg_punt_bio_wq) - return -ENOMEM; - return 0; + struct blkcg_gq *blkg, *ret_blkg = NULL; + + rcu_read_lock(); + blkg = blkg_lookup_create(css_to_blkcg(css), bio->bi_bdev->bd_disk); + while (blkg) { + if (blkg_tryget(blkg)) { + ret_blkg = blkg; + break; + } + blkg = blkg->parent; + } + rcu_read_unlock(); + + return ret_blkg; +} + +/** + * bio_associate_blkg_from_css - associate a bio with a specified css + * @bio: target bio + * @css: target css + * + * Associate @bio with the blkg found by combining the css's blkg and the + * request_queue of the @bio. An association failure is handled by walking up + * the blkg tree. Therefore, the blkg associated can be anything between @blkg + * and q->root_blkg. This situation only happens when a cgroup is dying and + * then the remaining bios will spill to the closest alive blkg. + * + * A reference will be taken on the blkg and will be released when @bio is + * freed. + */ +void bio_associate_blkg_from_css(struct bio *bio, + struct cgroup_subsys_state *css) +{ + if (bio->bi_blkg) + blkg_put(bio->bi_blkg); + + if (css && css->parent) { + bio->bi_blkg = blkg_tryget_closest(bio, css); + } else { + blkg_get(bdev_get_queue(bio->bi_bdev)->root_blkg); + bio->bi_blkg = bdev_get_queue(bio->bi_bdev)->root_blkg; + } +} +EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css); + +/** + * bio_associate_blkg - associate a bio with a blkg + * @bio: target bio + * + * Associate @bio with the blkg found from the bio's css and request_queue. + * If one is not found, bio_lookup_blkg() creates the blkg. If a blkg is + * already associated, the css is reused and association redone as the + * request_queue may have changed. + */ +void bio_associate_blkg(struct bio *bio) +{ + struct cgroup_subsys_state *css; + + if (blk_op_is_passthrough(bio->bi_opf)) + return; + + rcu_read_lock(); + + if (bio->bi_blkg) + css = bio_blkcg_css(bio); + else + css = blkcg_css(); + + bio_associate_blkg_from_css(bio, css); + + rcu_read_unlock(); +} +EXPORT_SYMBOL_GPL(bio_associate_blkg); + +/** + * bio_clone_blkg_association - clone blkg association from src to dst bio + * @dst: destination bio + * @src: source bio + */ +void bio_clone_blkg_association(struct bio *dst, struct bio *src) +{ + if (src->bi_blkg) + bio_associate_blkg_from_css(dst, bio_blkcg_css(src)); +} +EXPORT_SYMBOL_GPL(bio_clone_blkg_association); + +static int blk_cgroup_io_type(struct bio *bio) +{ + if (op_is_discard(bio->bi_opf)) + return BLKG_IOSTAT_DISCARD; + if (op_is_write(bio->bi_opf)) + return BLKG_IOSTAT_WRITE; + return BLKG_IOSTAT_READ; +} + +void blk_cgroup_bio_start(struct bio *bio) +{ + struct blkcg *blkcg = bio->bi_blkg->blkcg; + int rwd = blk_cgroup_io_type(bio), cpu; + struct blkg_iostat_set *bis; + unsigned long flags; + + if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) + return; + + /* Root-level stats are sourced from system-wide IO stats */ + if (!cgroup_parent(blkcg->css.cgroup)) + return; + + cpu = get_cpu(); + bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu); + flags = u64_stats_update_begin_irqsave(&bis->sync); + + /* + * If the bio is flagged with BIO_CGROUP_ACCT it means this is a split + * bio and we would have already accounted for the size of the bio. + */ + if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { + bio_set_flag(bio, BIO_CGROUP_ACCT); + bis->cur.bytes[rwd] += bio->bi_iter.bi_size; + } + bis->cur.ios[rwd]++; + + /* + * If the iostat_cpu isn't in a lockless list, put it into the + * list to indicate that a stat update is pending. + */ + if (!READ_ONCE(bis->lqueued)) { + struct llist_head *lhead = this_cpu_ptr(blkcg->lhead); + + llist_add(&bis->lnode, lhead); + WRITE_ONCE(bis->lqueued, true); + } + + u64_stats_update_end_irqrestore(&bis->sync, flags); + cgroup_rstat_updated(blkcg->css.cgroup, cpu); + put_cpu(); +} + +bool blk_cgroup_congested(void) +{ + struct cgroup_subsys_state *css; + bool ret = false; + + rcu_read_lock(); + for (css = blkcg_css(); css; css = css->parent) { + if (atomic_read(&css->cgroup->congestion_count)) { + ret = true; + break; + } + } + rcu_read_unlock(); + return ret; } -subsys_initcall(blkcg_init); module_param(blkcg_debug_stats, bool, 0644); MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not"); |