diff options
Diffstat (limited to 'block/blk-cgroup.c')
| -rw-r--r-- | block/blk-cgroup.c | 2100 |
1 files changed, 669 insertions, 1431 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 126c341..02cf633 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -11,1570 +11,612 @@ * Nauman Rafique <nauman@google.com> */ #include <linux/ioprio.h> -#include <linux/seq_file.h> #include <linux/kdev_t.h> #include <linux/module.h> #include <linux/err.h> #include <linux/blkdev.h> #include <linux/slab.h> -#include "blk-cgroup.h" #include <linux/genhd.h> +#include <linux/delay.h> +#include <linux/atomic.h> +#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(blkcg_pol_mutex); -struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT }; -EXPORT_SYMBOL_GPL(blkio_root_cgroup); +struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT }; +EXPORT_SYMBOL_GPL(blkcg_root); -/* 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) +static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; -static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg, - struct blkio_policy_node *pn) +struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { - list_add(&pn->node, &blkcg->policy_list); + return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), + struct blkcg, css); } +EXPORT_SYMBOL_GPL(cgroup_to_blkcg); -static inline bool cftype_blkg_same_policy(struct cftype *cft, - struct blkio_group *blkg) +static struct blkcg *task_blkcg(struct task_struct *tsk) { - enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); - - if (blkg->plid == plid) - return 1; - - return 0; + return container_of(task_subsys_state(tsk, blkio_subsys_id), + struct blkcg, css); } -/* Determines if policy node matches cgroup file being accessed */ -static inline bool pn_matches_cftype(struct cftype *cft, - struct blkio_policy_node *pn) +struct blkcg *bio_blkcg(struct bio *bio) { - enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); - int fileid = BLKIOFILE_ATTR(cft->private); - - return (plid == pn->plid && fileid == pn->fileid); + if (bio && bio->bi_css) + return container_of(bio->bi_css, struct blkcg, css); + return task_blkcg(current); } +EXPORT_SYMBOL_GPL(bio_blkcg); -/* Must be called with blkcg->lock held */ -static inline void blkio_policy_delete_node(struct blkio_policy_node *pn) +static bool blkcg_policy_enabled(struct request_queue *q, + const struct blkcg_policy *pol) { - list_del(&pn->node); + return pol && test_bit(pol->plid, q->blkcg_pols); } -/* Must be called with blkcg->lock held */ -static struct blkio_policy_node * -blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev, - enum blkio_policy_id plid, int fileid) +/** + * blkg_free - free a blkg + * @blkg: blkg to free + * + * Free @blkg which may be partially allocated. + */ +static void blkg_free(struct blkcg_gq *blkg) { - struct blkio_policy_node *pn; - - list_for_each_entry(pn, &blkcg->policy_list, node) { - if (pn->dev == dev && pn->plid == plid && pn->fileid == fileid) - return pn; - } + int i; - return NULL; -} + if (!blkg) + return; -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); + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; + struct blkg_policy_data *pd = blkg->pd[i]; -struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk) -{ - return container_of(task_subsys_state(tsk, blkio_subsys_id), - struct blkio_cgroup, css); -} -EXPORT_SYMBOL_GPL(task_blkio_cgroup); + if (!pd) + continue; -static inline void -blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight) -{ - struct blkio_policy_type *blkiop; + if (pol && pol->pd_exit_fn) + pol->pd_exit_fn(blkg); - list_for_each_entry(blkiop, &blkio_list, list) { - /* If this policy does not own the blkg, do not send updates */ - if (blkiop->plid != blkg->plid) - continue; - if (blkiop->ops.blkio_update_group_weight_fn) - blkiop->ops.blkio_update_group_weight_fn(blkg->key, - blkg, weight); + kfree(pd); } + + kfree(blkg); } -static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps, - int fileid) +/** + * 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 blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q) { - 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 != blkg->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->key, - blkg, bps); + struct blkcg_gq *blkg; + int i; - if (fileid == BLKIO_THROTL_write_bps_device - && blkiop->ops.blkio_update_group_write_bps_fn) - blkiop->ops.blkio_update_group_write_bps_fn(blkg->key, - blkg, bps); - } -} + /* alloc and init base part */ + blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node); + if (!blkg) + return NULL; -static inline void blkio_update_group_iops(struct blkio_group *blkg, - unsigned int iops, int fileid) -{ - struct blkio_policy_type *blkiop; + blkg->q = q; + INIT_LIST_HEAD(&blkg->q_node); + blkg->blkcg = blkcg; + blkg->refcnt = 1; - list_for_each_entry(blkiop, &blkio_list, list) { + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; + struct blkg_policy_data *pd; - /* If this policy does not own the blkg, do not send updates */ - if (blkiop->plid != blkg->plid) + if (!blkcg_policy_enabled(q, pol)) 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->key, - blkg, iops); + /* alloc per-policy data and attach it to blkg */ + pd = kzalloc_node(pol->pd_size, GFP_ATOMIC, q->node); + if (!pd) { + blkg_free(blkg); + return NULL; + } - if (fileid == BLKIO_THROTL_write_iops_device - && blkiop->ops.blkio_update_group_write_iops_fn) - blkiop->ops.blkio_update_group_write_iops_fn(blkg->key, - blkg,iops); + blkg->pd[i] = pd; + pd->blkg = blkg; } -} -/* - * 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; -} + /* invoke per-policy init */ + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; -/* - * 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]--; + if (blkcg_policy_enabled(blkg->q, pol)) + pol->pd_init_fn(blkg); } -} -#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_group *curr_blkg) -{ - if (blkio_blkg_waiting(&blkg->stats)) - return; - if (blkg == curr_blkg) - return; - blkg->stats.start_group_wait_time = sched_clock(); - blkio_mark_blkg_waiting(&blkg->stats); + return blkg; } -/* This should be called with the blkg->stats_lock held. */ -static void blkio_update_group_wait_time(struct blkio_group_stats *stats) +static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, + struct request_queue *q) { - unsigned long long now; + struct blkcg_gq *blkg; - if (!blkio_blkg_waiting(stats)) - return; + blkg = rcu_dereference(blkcg->blkg_hint); + if (blkg && blkg->q == q) + return blkg; - 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); + /* + * Hint didn't match. Look up from the radix tree. Note that we + * may not be holding queue_lock and thus are not sure whether + * @blkg from blkg_tree has already been removed or not, so we + * can't update hint to the lookup result. Leave it to the caller. + */ + blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); + if (blkg && blkg->q == q) + return blkg; + + return NULL; } -/* This should be called with the blkg->stats_lock held. */ -static void blkio_end_empty_time(struct blkio_group_stats *stats) +/** + * blkg_lookup - lookup blkg for the specified blkcg - q pair + * @blkcg: blkcg of interest + * @q: request_queue of interest + * + * Lookup blkg for the @blkcg - @q pair. This function should be called + * under RCU read lock and is guaranteed to return %NULL if @q is bypassing + * - see blk_queue_bypass_start() for details. + */ +struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) { - unsigned long long now; - - if (!blkio_blkg_empty(stats)) - return; + WARN_ON_ONCE(!rcu_read_lock_held()); - now = sched_clock(); - if (time_after64(now, stats->start_empty_time)) - stats->empty_time += now - stats->start_empty_time; - blkio_clear_blkg_empty(stats); + if (unlikely(blk_queue_bypass(q))) + return NULL; + return __blkg_lookup(blkcg, q); } +EXPORT_SYMBOL_GPL(blkg_lookup); -void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg) +static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) + __releases(q->queue_lock) __acquires(q->queue_lock) { - unsigned long flags; + struct blkcg_gq *blkg; + int ret; - spin_lock_irqsave(&blkg->stats_lock, flags); - BUG_ON(blkio_blkg_idling(&blkg->stats)); - blkg->stats.start_idle_time = sched_clock(); - blkio_mark_blkg_idling(&blkg->stats); - spin_unlock_irqrestore(&blkg->stats_lock, flags); -} -EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats); + WARN_ON_ONCE(!rcu_read_lock_held()); + lockdep_assert_held(q->queue_lock); -void blkiocg_update_idle_time_stats(struct blkio_group *blkg) -{ - unsigned long flags; - unsigned long long now; - struct blkio_group_stats *stats; - - spin_lock_irqsave(&blkg->stats_lock, flags); - stats = &blkg->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); + /* lookup and update hint on success, see __blkg_lookup() for details */ + blkg = __blkg_lookup(blkcg, q); + if (blkg) { + rcu_assign_pointer(blkcg->blkg_hint, blkg); + return blkg; } - 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) -{ - unsigned long flags; - struct blkio_group_stats *stats; - - spin_lock_irqsave(&blkg->stats_lock, flags); - stats = &blkg->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); + /* blkg holds a reference to blkcg */ + if (!css_tryget(&blkcg->css)) + return ERR_PTR(-EINVAL); -void blkiocg_set_start_empty_time(struct blkio_group *blkg) -{ - unsigned long flags; - struct blkio_group_stats *stats; + /* allocate */ + ret = -ENOMEM; + blkg = blkg_alloc(blkcg, q); + if (unlikely(!blkg)) + goto err_put; - spin_lock_irqsave(&blkg->stats_lock, flags); - stats = &blkg->stats; + /* insert */ + ret = radix_tree_preload(GFP_ATOMIC); + if (ret) + goto err_free; - 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; + spin_lock(&blkcg->lock); + ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); + if (likely(!ret)) { + hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); + list_add(&blkg->q_node, &q->blkg_list); } + spin_unlock(&blkcg->lock); - /* - * 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; - } + radix_tree_preload_end(); - stats->start_empty_time = sched_clock(); - blkio_mark_blkg_empty(stats); - spin_unlock_irqrestore(&blkg->stats_lock, flags); + if (!ret) + return blkg; +err_free: + blkg_free(blkg); +err_put: + css_put(&blkcg->css); + return ERR_PTR(ret); } -EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time); -void blkiocg_update_dequeue_stats(struct blkio_group *blkg, - unsigned long dequeue) +struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) { - blkg->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_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_group *curr_blkg, bool direction, - bool sync) -{ - unsigned long flags; - - spin_lock_irqsave(&blkg->stats_lock, flags); - blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction, - sync); - blkio_end_empty_time(&blkg->stats); - blkio_set_start_group_wait_time(blkg, curr_blkg); - spin_unlock_irqrestore(&blkg->stats_lock, flags); + /* + * This could be the first entry point of blkcg implementation and + * we shouldn't allow anything to go through for a bypassing queue. + */ + if (unlikely(blk_queue_bypass(q))) + return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY); + return __blkg_lookup_create(blkcg, q); } -EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats); +EXPORT_SYMBOL_GPL(blkg_lookup_create); -void blkiocg_update_io_remove_stats(struct blkio_group *blkg, - bool direction, bool sync) +static void blkg_destroy(struct blkcg_gq *blkg) { - unsigned long flags; + struct request_queue *q = blkg->q; + struct blkcg *blkcg = blkg->blkcg; - spin_lock_irqsave(&blkg->stats_lock, flags); - blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], - direction, sync); - spin_unlock_irqrestore(&blkg->stats_lock, flags); -} -EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats); + lockdep_assert_held(q->queue_lock); + lockdep_assert_held(&blkcg->lock); -void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time, - unsigned long unaccounted_time) -{ - unsigned long flags; - - spin_lock_irqsave(&blkg->stats_lock, flags); - blkg->stats.time += time; -#ifdef CONFIG_DEBUG_BLK_CGROUP - blkg->stats.unaccounted_time += unaccounted_time; -#endif - spin_unlock_irqrestore(&blkg->stats_lock, flags); -} -EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used); + /* 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)); -/* - * 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, - uint64_t bytes, bool direction, bool sync) -{ - struct blkio_group_stats_cpu *stats_cpu; - unsigned long flags; + radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); + list_del_init(&blkg->q_node); + hlist_del_init_rcu(&blkg->blkcg_node); /* - * Disabling interrupts to provide mutual exclusion between two - * writes on same cpu. It probably is not needed for 64bit. Not - * optimizing that case yet. + * Both setting lookup hint to and clearing it from @blkg are done + * under queue_lock. If it's not pointing to @blkg now, it never + * will. Hint assignment itself can race safely. */ - local_irq_save(flags); - - stats_cpu = this_cpu_ptr(blkg->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, - uint64_t start_time, uint64_t io_start_time, bool direction, bool sync) -{ - struct blkio_group_stats *stats; - unsigned long flags; - unsigned long long now = sched_clock(); - - spin_lock_irqsave(&blkg->stats_lock, flags); - stats = &blkg->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, bool direction, - bool sync) -{ - struct blkio_group_stats_cpu *stats_cpu; - unsigned long flags; + if (rcu_dereference_raw(blkcg->blkg_hint) == blkg) + rcu_assign_pointer(blkcg->blkg_hint, NULL); /* - * Disabling interrupts to provide mutual exclusion between two - * writes on same cpu. It probably is not needed for 64bit. Not - * optimizing that case yet. + * Put the reference taken at the time of creation so that when all + * queues are gone, group can be destroyed. */ - local_irq_save(flags); - - stats_cpu = this_cpu_ptr(blkg->stats_cpu); - - u64_stats_update_begin(&stats_cpu->syncp); - blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_MERGED], 1, - direction, sync); - u64_stats_update_end(&stats_cpu->syncp); - local_irq_restore(flags); + blkg_put(blkg); } -EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats); -/* - * This function allocates the per cpu stats for blkio_group. Should be called - * from sleepable context as alloc_per_cpu() requires that. +/** + * blkg_destroy_all - destroy all blkgs associated with a request_queue + * @q: request_queue of interest + * + * Destroy all blkgs associated with @q. */ -int blkio_alloc_blkg_stats(struct blkio_group *blkg) +static void blkg_destroy_all(struct request_queue *q) { - /* Allocate memory for per cpu stats */ - blkg->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu); - if (!blkg->stats_cpu) - return -ENOMEM; - return 0; -} -EXPORT_SYMBOL_GPL(blkio_alloc_blkg_stats); + struct blkcg_gq *blkg, *n; -void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, - struct blkio_group *blkg, void *key, dev_t dev, - enum blkio_policy_id plid) -{ - unsigned long flags; - - spin_lock_irqsave(&blkcg->lock, flags); - spin_lock_init(&blkg->stats_lock); - rcu_assign_pointer(blkg->key, key); - blkg->blkcg_id = css_id(&blkcg->css); - hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); - blkg->plid = plid; - spin_unlock_irqrestore(&blkcg->lock, flags); - /* Need to take css reference ? */ - cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path)); - blkg->dev = dev; -} -EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group); + lockdep_assert_held(q->queue_lock); -static void __blkiocg_del_blkio_group(struct blkio_group *blkg) -{ - hlist_del_init_rcu(&blkg->blkcg_node); - blkg->blkcg_id = 0; -} + list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { + struct blkcg *blkcg = blkg->blkcg; -/* - * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1 - * indicating that blk_group was unhashed by the time we got to it. - */ -int blkiocg_del_blkio_group(struct blkio_group *blkg) -{ - struct blkio_cgroup *blkcg; - unsigned long flags; - struct cgroup_subsys_state *css; - int ret = 1; - - rcu_read_lock(); - css = css_lookup(&blkio_subsys, blkg->blkcg_id); - if (css) { - blkcg = container_of(css, struct blkio_cgroup, css); - spin_lock_irqsave(&blkcg->lock, flags); - if (!hlist_unhashed(&blkg->blkcg_node)) { - __blkiocg_del_blkio_group(blkg); - ret = 0; - } - spin_unlock_irqrestore(&blkcg->lock, flags); + spin_lock(&blkcg->lock); + blkg_destroy(blkg); + spin_unlock(&blkcg->lock); } - - rcu_read_unlock(); - return ret; } -EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group); -/* called under rcu_read_lock(). */ -struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) +static void blkg_rcu_free(struct rcu_head *rcu_head) { - struct blkio_group *blkg; - struct hlist_node *n; - void *__key; - - hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) { - __key = blkg->key; - if (__key == key) - return blkg; - } - - return NULL; + blkg_free(container_of(rcu_head, struct blkcg_gq, rcu_head)); } -EXPORT_SYMBOL_GPL(blkiocg_lookup_group); -static void blkio_reset_stats_cpu(struct blkio_group *blkg) +void __blkg_release(struct blkcg_gq *blkg) { - struct blkio_group_stats_cpu *stats_cpu; - int i, j, k; + /* release the extra blkcg reference this blkg has been holding */ + css_put(&blkg->blkcg->css); + /* - * Note: On 64 bit arch this should not be an issue. This has the - * possibility of returning some inconsistent value on 32bit arch - * as 64bit update on 32bit is non atomic. Taking care of this - * corner case makes code very complicated, like sending IPIs to - * cpus, taking care of stats of offline cpus etc. + * 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. * - * reset stats is anyway more of a debug feature and this sounds a - * corner case. So I am not complicating the code yet until and - * unless this becomes a real issue. + * Having a reference to blkg under an rcu allows acess to only + * values local to groups like group stats and group rate limits */ - for_each_possible_cpu(i) { - stats_cpu = per_cpu_ptr(blkg->stats_cpu, i); - stats_cpu->sectors = 0; - for(j = 0; j < BLKIO_STAT_CPU_NR; j++) - for (k = 0; k < BLKIO_STAT_TOTAL; k++) - stats_cpu->stat_arr_cpu[j][k] = 0; - } + call_rcu(&blkg->rcu_head, blkg_rcu_free); } +EXPORT_SYMBOL_GPL(__blkg_release); -static int -blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val) +static int blkcg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, + u64 val) { - struct blkio_cgroup *blkcg; - struct blkio_group *blkg; - struct blkio_group_stats *stats; + struct blkcg *blkcg = cgroup_to_blkcg(cgroup); + struct blkcg_gq *blkg; struct hlist_node *n; - uint64_t queued[BLKIO_STAT_TOTAL]; int i; -#ifdef CONFIG_DEBUG_BLK_CGROUP - bool idling, waiting, empty; - unsigned long long now = sched_clock(); -#endif - blkcg = cgroup_to_blkio_cgroup(cgroup); + mutex_lock(&blkcg_pol_mutex); spin_lock_irq(&blkcg->lock); - hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { - spin_lock(&blkg->stats_lock); - stats = &blkg->stats; -#ifdef CONFIG_DEBUG_BLK_CGROUP - idling = blkio_blkg_idling(stats); - waiting = blkio_blkg_waiting(stats); - empty = blkio_blkg_empty(stats); -#endif - for (i = 0; i < BLKIO_STAT_TOTAL; i++) - queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i]; - memset(stats, 0, sizeof(struct blkio_group_stats)); - for (i = 0; i < BLKIO_STAT_TOTAL; i++) - stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i]; -#ifdef CONFIG_DEBUG_BLK_CGROUP - if (idling) { - blkio_mark_blkg_idling(stats); - stats->start_idle_time = now; - } - if (waiting) { - blkio_mark_blkg_waiting(stats); - stats->start_group_wait_time = now; - } - if (empty) { - blkio_mark_blkg_empty(stats); - stats->start_empty_time = now; - } -#endif - spin_unlock(&blkg->stats_lock); - - /* Reset Per cpu stats which don't take blkg->stats_lock */ - blkio_reset_stats_cpu(blkg); - } - - spin_unlock_irq(&blkcg->lock); - return 0; -} - -static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str, - int chars_left, bool diskname_only) -{ - snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev)); - 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, dev_t dev) -{ - blkio_get_key_name(0, dev, str, chars_left, true); - cb->fill(cb, str, val); - return val; -} - - -static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg, - enum stat_type_cpu type, enum stat_sub_type sub_type) -{ - int cpu; - struct blkio_group_stats_cpu *stats_cpu; - u64 val = 0, tval; - - for_each_possible_cpu(cpu) { - unsigned int start; - stats_cpu = per_cpu_ptr(blkg->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, - struct cgroup_map_cb *cb, dev_t dev, 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, type, 0); - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, val, cb, dev); - } - - for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL; - sub_type++) { - blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false); - val = blkio_read_stat_cpu(blkg, type, sub_type); - cb->fill(cb, key_str, val); - } - - disk_total = blkio_read_stat_cpu(blkg, type, BLKIO_STAT_READ) + - blkio_read_stat_cpu(blkg, type, BLKIO_STAT_WRITE); - - blkio_get_key_name(BLKIO_STAT_TOTAL, dev, 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, - struct cgroup_map_cb *cb, dev_t dev, enum stat_type type) -{ - 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, - blkg->stats.time, cb, dev); -#ifdef CONFIG_DEBUG_BLK_CGROUP - if (type == BLKIO_STAT_UNACCOUNTED_TIME) - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, - blkg->stats.unaccounted_time, cb, dev); - if (type == BLKIO_STAT_AVG_QUEUE_SIZE) { - uint64_t sum = blkg->stats.avg_queue_size_sum; - uint64_t samples = blkg->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, dev); - } - if (type == BLKIO_STAT_GROUP_WAIT_TIME) - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, - blkg->stats.group_wait_time, cb, dev); - if (type == BLKIO_STAT_IDLE_TIME) - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, - blkg->stats.idle_time, cb, dev); - if (type == BLKIO_STAT_EMPTY_TIME) - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, - blkg->stats.empty_time, cb, dev); - if (type == BLKIO_STAT_DEQUEUE) - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, - blkg->stats.dequeue, cb, dev); -#endif - - for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL; - sub_type++) { - blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false); - cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]); - } - disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] + - blkg->stats.stat_arr[type][BLKIO_STAT_WRITE]; - blkio_get_key_name(BLKIO_STAT_TOTAL, dev, 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, - struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid) -{ - struct gendisk *disk = NULL; - 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; - - /* For rule removal, do not check for device presence. */ - if (temp) { - disk = get_gendisk(dev, &part); - if (!disk || part) { - ret = -ENODEV; - goto out; - } - } - - newpn->dev = dev; - - switch (plid) { - case BLKIO_POLICY_PROP: - if ((temp < BLKIO_WEIGHT_MIN && temp > 0) || - temp > BLKIO_WEIGHT_MAX) - goto out; - - newpn->plid = plid; - newpn->fileid = fileid; - newpn->val.weight = temp; - break; - case BLKIO_POLICY_THROTL: - switch(fileid) { - case BLKIO_THROTL_read_bps_device: - case BLKIO_THROTL_write_bps_device: - newpn->plid = plid; - newpn->fileid = fileid; - newpn->val.bps = temp; - break; - case BLKIO_THROTL_read_iops_device: - case BLKIO_THROTL_write_iops_device: - if (temp > THROTL_IOPS_MAX) - goto out; - - newpn->plid = plid; - newpn->fileid = fileid; - newpn->val.iops = (unsigned int)temp; - break; - } - break; - default: - BUG(); - } - ret = 0; -out: - put_disk(disk); - return ret; -} - -unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg, - dev_t dev) -{ - struct blkio_policy_node *pn; - unsigned long flags; - unsigned int weight; - - spin_lock_irqsave(&blkcg->lock, flags); - - pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP, - BLKIO_PROP_weight_device); - if (pn) - weight = pn->val.weight; - else - weight = blkcg->weight; - - spin_unlock_irqrestore(&blkcg->lock, flags); - - return weight; -} -EXPORT_SYMBOL_GPL(blkcg_get_weight); - -uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev) -{ - struct blkio_policy_node *pn; - unsigned long flags; - uint64_t bps = -1; - - spin_lock_irqsave(&blkcg->lock, flags); - pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL, - BLKIO_THROTL_read_bps_device); - if (pn) - bps = pn->val.bps; - spin_unlock_irqrestore(&blkcg->lock, flags); - - return bps; -} - -uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev) -{ - struct blkio_policy_node *pn; - unsigned long flags; - uint64_t bps = -1; - - spin_lock_irqsave(&blkcg->lock, flags); - pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL, - BLKIO_THROTL_write_bps_device); - if (pn) - bps = pn->val.bps; - spin_unlock_irqrestore(&blkcg->lock, flags); - - return bps; -} - -unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev) -{ - struct blkio_policy_node *pn; - unsigned long flags; - unsigned int iops = -1; - - spin_lock_irqsave(&blkcg->lock, flags); - pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL, - BLKIO_THROTL_read_iops_device); - if (pn) - iops = pn->val.iops; - spin_unlock_irqrestore(&blkcg->lock, flags); - - return iops; -} - -unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev) -{ - struct blkio_policy_node *pn; - unsigned long flags; - unsigned int iops = -1; - - spin_lock_irqsave(&blkcg->lock, flags); - pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL, - BLKIO_THROTL_write_iops_device); - if (pn) - iops = pn->val.iops; - spin_unlock_irqrestore(&blkcg->lock, flags); - - return iops; -} + /* + * 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) { + for (i = 0; i < BLKCG_MAX_POLS; i++) { + struct blkcg_policy *pol = blkcg_policy[i]; -/* Checks whether user asked for deleting a policy rule */ -static bool blkio_delete_rule_command(struct blkio_policy_node *pn) -{ - switch(pn->plid) { - case BLKIO_POLICY_PROP: - if (pn->val.weight == 0) - return 1; - break; - case BLKIO_POLICY_THROTL: - switch(pn->fileid) { - case BLKIO_THROTL_read_bps_device: - case BLKIO_THROTL_write_bps_device: - if (pn->val.bps == 0) - return 1; - break; - case BLKIO_THROTL_read_iops_device: - case BLKIO_THROTL_write_iops_device: - if (pn->val.iops == 0) - return 1; + if (blkcg_policy_enabled(blkg->q, pol) && + pol->pd_reset_stats_fn) + pol->pd_reset_stats_fn(blkg); } - break; - default: - BUG(); } + spin_unlock_irq(&blkcg->lock); + mutex_unlock(&blkcg_pol_mutex); return 0; } -static void blkio_update_policy_rule(struct blkio_policy_node *oldpn, - struct blkio_policy_node *newpn) -{ - switch(oldpn->plid) { - case BLKIO_POLICY_PROP: - oldpn->val.weight = newpn->val.weight; - break; - case BLKIO_POLICY_THROTL: - switch(newpn->fileid) { - case BLKIO_THROTL_read_bps_device: - case BLKIO_THROTL_write_bps_device: - oldpn->val.bps = newpn->val.bps; - break; - case BLKIO_THROTL_read_iops_device: - case BLKIO_THROTL_write_iops_device: - oldpn->val.iops = newpn->val.iops; - } - break; - default: - BUG(); - } -} - -/* - * Some rules/values in blkg have changed. Propagate those to respective - * policies. - */ -static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg, - struct blkio_group *blkg, struct blkio_policy_node *pn) +static const char *blkg_dev_name(struct blkcg_gq *blkg) { - unsigned int weight, iops; - u64 bps; - - switch(pn->plid) { - case BLKIO_POLICY_PROP: - weight = pn->val.weight ? pn->val.weight : - blkcg->weight; - blkio_update_group_weight(blkg, weight); - break; - case BLKIO_POLICY_THROTL: - switch(pn->fileid) { - case BLKIO_THROTL_read_bps_device: - case BLKIO_THROTL_write_bps_device: - bps = pn->val.bps ? pn->val.bps : (-1); - blkio_update_group_bps(blkg, bps, pn->fileid); - break; - case BLKIO_THROTL_read_iops_device: - case BLKIO_THROTL_write_iops_device: - iops = pn->val.iops ? pn->val.iops : (-1); - blkio_update_group_iops(blkg, iops, pn->fileid); - break; - } - break; - default: - BUG(); - } + /* 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; } -/* - * A policy node rule has been updated. Propagate this update to all the - * block groups which might be affected by this update. +/** + * blkcg_print_blkgs - helper for printing per-blkg data + * @sf: seq_file to print to + * @blkcg: blkcg of interest + * @prfill: fill function to print out a blkg + * @pol: policy in question + * @data: data to be passed to @prfill + * @show_total: to print out sum of prfill return values or not + * + * This function invokes @prfill on each blkg of @blkcg if pd for the + * policy specified by @pol exists. @prfill is invoked with @sf, the + * policy data and @data. If @show_total is %true, the sum of the return + * values from @prfill is printed with "Total" label at the end. + * + * This is to be used to construct print functions for + * cftype->read_seq_string method. */ -static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg, - struct blkio_policy_node *pn) +void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, + u64 (*prfill)(struct seq_file *, + struct blkg_policy_data *, int), + const struct blkcg_policy *pol, int data, + bool show_total) { - struct blkio_group *blkg; + struct blkcg_gq *blkg; struct hlist_node *n; + u64 total = 0; - spin_lock(&blkio_list_lock); spin_lock_irq(&blkcg->lock); - - hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { - if (pn->dev != blkg->dev || pn->plid != blkg->plid) - continue; - blkio_update_blkg_policy(blkcg, blkg, pn); - } - + hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) + if (blkcg_policy_enabled(blkg->q, pol)) + total += prfill(sf, blkg->pd[pol->plid], data); spin_unlock_irq(&blkcg->lock); - spin_unlock(&blkio_list_lock); + + if (show_total) + seq_printf(sf, "Total %llu\n", (unsigned long long)total); } +EXPORT_SYMBOL_GPL(blkcg_print_blkgs); -static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft, - const char *buffer) +/** + * __blkg_prfill_u64 - prfill helper for a single u64 value + * @sf: seq_file to print to + * @pd: policy private data of interest + * @v: value to print + * + * Print @v to @sf for the device assocaited with @pd. + */ +u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) { - int ret = 0; - char *buf; - struct blkio_policy_node *newpn, *pn; - struct blkio_cgroup *blkcg; - int keep_newpn = 0; - enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private); - int fileid = BLKIOFILE_ATTR(cft->private); - - buf = kstrdup(buffer, GFP_KERNEL); - if (!buf) - return -ENOMEM; - - newpn = kzalloc(sizeof(*newpn), GFP_KERNEL); - if (!newpn) { - ret = -ENOMEM; - goto free_buf; - } - - ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid); - if (ret) - goto free_newpn; - - blkcg = cgroup_to_blkio_cgroup(cgrp); - - spin_lock_irq(&blkcg->lock); - - pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid); - if (!pn) { - if (!blkio_delete_rule_command(newpn)) { - blkio_policy_insert_node(blkcg, newpn); - keep_newpn = 1; - } - spin_unlock_irq(&blkcg->lock); - goto update_io_group; - } - - if (blkio_delete_rule_command(newpn)) { - blkio_policy_delete_node(pn); - kfree(pn); - spin_unlock_irq(&blkcg->lock); - goto update_io_group; - } - spin_unlock_irq(&blkcg->lock); + const char *dname = blkg_dev_name(pd->blkg); - blkio_update_policy_rule(pn, newpn); + if (!dname) + return 0; -update_io_group: - blkio_update_policy_node_blkg(blkcg, newpn); - -free_newpn: - if (!keep_newpn) - kfree(newpn); -free_buf: - kfree(buf); - return ret; + seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); + return v; } +EXPORT_SYMBOL_GPL(__blkg_prfill_u64); -static void -blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn) -{ - switch(pn->plid) { - case BLKIO_POLICY_PROP: - if (pn->fileid == BLKIO_PROP_weight_device) - seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev), - MINOR(pn->dev), pn->val.weight); - break; - case BLKIO_POLICY_THROTL: - switch(pn->fileid) { - case BLKIO_THROTL_read_bps_device: - case BLKIO_THROTL_write_bps_device: - seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev), - MINOR(pn->dev), pn->val.bps); - break; - case BLKIO_THROTL_read_iops_device: - case BLKIO_THROTL_write_iops_device: - seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev), - MINOR(pn->dev), pn->val.iops); - break; - } - break; - default: - BUG(); - } -} +/** + * __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 *rwstat) +{ + static const char *rwstr[] = { + [BLKG_RWSTAT_READ] = "Read", + [BLKG_RWSTAT_WRITE] = "Write", + [BLKG_RWSTAT_SYNC] = "Sync", + [BLKG_RWSTAT_ASYNC] = "Async", + }; + const char *dname = blkg_dev_name(pd->blkg); + u64 v; + int i; -/* cgroup files which read their data from policy nodes end up here */ -static void blkio_read_policy_node_files(struct cftype *cft, - struct blkio_cgroup *blkcg, struct seq_file *m) -{ - struct blkio_policy_node *pn; - - if (!list_empty(&blkcg->policy_list)) { - spin_lock_irq(&blkcg->lock); - list_for_each_entry(pn, &blkcg->policy_list, node) { - if (!pn_matches_cftype(cft, pn)) - continue; - blkio_print_policy_node(m, pn); - } - spin_unlock_irq(&blkcg->lock); - } -} + if (!dname) + return 0; -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_policy_node_files(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_policy_node_files(cft, blkcg, m); - return 0; - default: - BUG(); - } - break; - default: - BUG(); - } + for (i = 0; i < BLKG_RWSTAT_NR; i++) + seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], + (unsigned long long)rwstat->cnt[i]); - return 0; + v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE]; + seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); + return v; } -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) +/** + * blkg_prfill_stat - prfill callback for blkg_stat + * @sf: seq_file to print to + * @pd: policy private data of interest + * @off: offset to the blkg_stat in @pd + * + * prfill callback for printing a blkg_stat. + */ +u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) { - struct blkio_group *blkg; - struct hlist_node *n; - uint64_t cgroup_total = 0; - - rcu_read_lock(); - hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) { - if (blkg->dev) { - if (!cftype_blkg_same_policy(cft, blkg)) - continue; - if (pcpu) - cgroup_total += blkio_get_stat_cpu(blkg, cb, - blkg->dev, type); - else { - spin_lock_irq(&blkg->stats_lock); - cgroup_total += blkio_get_stat(blkg, cb, - blkg->dev, type); - spin_unlock_irq(&blkg->stats_lock); - } - } - } - if (show_total) - cb->fill(cb, "Total", cgroup_total); - rcu_read_unlock(); - return 0; + return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); } +EXPORT_SYMBOL_GPL(blkg_prfill_stat); -/* 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) +/** + * 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 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_CPU_MERGED, 1, 1); - 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(); - } + struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); - return 0; + return __blkg_prfill_rwstat(sf, pd, &rwstat); } +EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); -static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val) +/** + * 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 + * + * Parse per-blkg config update from @input and initialize @ctx with the + * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new + * value. This function returns with RCU read lock and queue lock held and + * must be paired with blkg_conf_finish(). + */ +int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, + const char *input, struct blkg_conf_ctx *ctx) + __acquires(rcu) __acquires(disk->queue->queue_lock) { - struct blkio_group *blkg; - struct hlist_node *n; - struct blkio_policy_node *pn; + struct gendisk *disk; + struct blkcg_gq *blkg; + unsigned int major, minor; + unsigned long long v; + int part, ret; - if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX) + if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3) 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) { - pn = blkio_policy_search_node(blkcg, blkg->dev, - BLKIO_POLICY_PROP, BLKIO_PROP_weight_device); - if (pn) - continue; - - blkio_update_group_weight(blkg, blkcg->weight); - } - spin_unlock_irq(&blkcg->lock); - spin_unlock(&blkio_list_lock); - return 0; -} + disk = get_gendisk(MKDEV(major, minor), &part); + if (!disk || part) + return -EINVAL; -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); + rcu_read_lock(); + spin_lock_irq(disk->queue->queue_lock); - blkcg = cgroup_to_blkio_cgroup(cgrp); + if (blkcg_policy_enabled(disk->queue, pol)) + blkg = blkg_lookup_create(blkcg, disk->queue); + else + blkg = ERR_PTR(-EINVAL); - switch(plid) { - case BLKIO_POLICY_PROP: - switch(name) { - case BLKIO_PROP_weight: - return (u64)blkcg->weight; + if (IS_ERR(blkg)) { + ret = PTR_ERR(blkg); + rcu_read_unlock(); + spin_unlock_irq(disk->queue->queue_lock); + 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); + ret = restart_syscall(); } - break; - default: - BUG(); + return ret; } + + ctx->disk = disk; + ctx->blkg = blkg; + ctx->v = v; return 0; } +EXPORT_SYMBOL_GPL(blkg_conf_prep); -static int -blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val) +/** + * blkg_conf_finish - finish up per-blkg config update + * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() + * + * Finish up after per-blkg config update. This function must be paired + * with blkg_conf_prep(). + */ +void blkg_conf_finish(struct blkg_conf_ctx *ctx) + __releases(ctx->disk->queue->queue_lock) __releases(rcu) { - 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, val); - } - break; - default: - BUG(); - } - - return 0; + spin_unlock_irq(ctx->disk->queue->queue_lock); + rcu_read_unlock(); + put_disk(ctx->disk); } +EXPORT_SYMBOL_GPL(blkg_conf_finish); -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, - }, +struct cftype blkcg_files[] = { { .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, + .write_u64 = blkcg_reset_stats, }, - { - .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 { } /* terminate */ }; -static void blkiocg_destroy(struct cgroup *cgroup) +/** + * blkcg_pre_destroy - cgroup pre_destroy callback + * @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 blkcg_pre_destroy(struct cgroup *cgroup) { - struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); - unsigned long flags; - struct blkio_group *blkg; - void *key; - struct blkio_policy_type *blkiop; - struct blkio_policy_node *pn, *pntmp; + struct blkcg *blkcg = cgroup_to_blkcg(cgroup); - rcu_read_lock(); - do { - spin_lock_irqsave(&blkcg->lock, flags); + spin_lock_irq(&blkcg->lock); - if (hlist_empty(&blkcg->blkg_list)) { - spin_unlock_irqrestore(&blkcg->lock, flags); - break; + while (!hlist_empty(&blkcg->blkg_list)) { + struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, + 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 { + spin_unlock_irq(&blkcg->lock); + cpu_relax(); + spin_lock_irq(&blkcg->lock); } + } - blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group, - blkcg_node); - key = rcu_dereference(blkg->key); - __blkiocg_del_blkio_group(blkg); - - spin_unlock_irqrestore(&blkcg->lock, flags); - - /* - * This blkio_group is being unlinked as associated cgroup is - * going away. Let all the IO controlling policies know about - * this event. - */ - spin_lock(&blkio_list_lock); - list_for_each_entry(blkiop, &blkio_list, list) { - if (blkiop->plid != blkg->plid) - continue; - blkiop->ops.blkio_unlink_group_fn(key, blkg); - } - spin_unlock(&blkio_list_lock); - } while (1); + spin_unlock_irq(&blkcg->lock); + return 0; +} - list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) { - blkio_policy_delete_node(pn); - kfree(pn); - } +static void blkcg_destroy(struct cgroup *cgroup) +{ + struct blkcg *blkcg = cgroup_to_blkcg(cgroup); - free_css_id(&blkio_subsys, &blkcg->css); - rcu_read_unlock(); - if (blkcg != &blkio_root_cgroup) + if (blkcg != &blkcg_root) kfree(blkcg); } -static struct cgroup_subsys_state *blkiocg_create(struct cgroup *cgroup) +static struct cgroup_subsys_state *blkcg_create(struct cgroup *cgroup) { - struct blkio_cgroup *blkcg; + static atomic64_t id_seq = ATOMIC64_INIT(0); + struct blkcg *blkcg; struct cgroup *parent = cgroup->parent; if (!parent) { - blkcg = &blkio_root_cgroup; + blkcg = &blkcg_root; goto done; } @@ -1582,22 +624,68 @@ static struct cgroup_subsys_state *blkiocg_create(struct cgroup *cgroup) if (!blkcg) return ERR_PTR(-ENOMEM); - blkcg->weight = BLKIO_WEIGHT_DEFAULT; + blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT; + blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */ done: spin_lock_init(&blkcg->lock); + INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC); INIT_HLIST_HEAD(&blkcg->blkg_list); - INIT_LIST_HEAD(&blkcg->policy_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) +{ + might_sleep(); + + return blk_throtl_init(q); +} + +/** + * 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) +{ + spin_lock_irq(q->queue_lock); + blkg_destroy_all(q); + spin_unlock_irq(q->queue_lock); + + 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 *cgrp, struct cgroup_taskset *tset) +static int blkcg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) { struct task_struct *task; struct io_context *ioc; @@ -1616,63 +704,213 @@ static int blkiocg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) return ret; } -static void blkiocg_attach(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); - } - } -} - struct cgroup_subsys blkio_subsys = { .name = "blkio", - .create = blkiocg_create, - .can_attach = blkiocg_can_attach, - .attach = blkiocg_attach, - .destroy = blkiocg_destroy, -#ifdef CONFIG_BLK_CGROUP - /* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */ + .create = blkcg_create, + .can_attach = blkcg_can_attach, + .pre_destroy = blkcg_pre_destroy, + .destroy = blkcg_destroy, .subsys_id = blkio_subsys_id, -#endif - .base_cftypes = blkio_files, - .use_id = 1, + .base_cftypes = blkcg_files, .module = THIS_MODULE, }; EXPORT_SYMBOL_GPL(blkio_subsys); -void blkio_policy_register(struct blkio_policy_type *blkiop) +/** + * blkcg_activate_policy - activate a blkcg policy on a request_queue + * @q: request_queue of interest + * @pol: blkcg policy to activate + * + * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through + * bypass mode to populate its blkgs with policy_data for @pol. + * + * Activation happens with @q 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. + * + * 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) { - spin_lock(&blkio_list_lock); - list_add_tail(&blkiop->list, &blkio_list); - spin_unlock(&blkio_list_lock); + LIST_HEAD(pds); + struct blkcg_gq *blkg; + struct blkg_policy_data *pd, *n; + int cnt = 0, ret; + + if (blkcg_policy_enabled(q, pol)) + return 0; + + blk_queue_bypass_start(q); + + /* make sure the root blkg exists and count the existing blkgs */ + spin_lock_irq(q->queue_lock); + + rcu_read_lock(); + blkg = __blkg_lookup_create(&blkcg_root, q); + rcu_read_unlock(); + + if (IS_ERR(blkg)) { + ret = PTR_ERR(blkg); + goto out_unlock; + } + q->root_blkg = blkg; + + list_for_each_entry(blkg, &q->blkg_list, q_node) + cnt++; + + spin_unlock_irq(q->queue_lock); + + /* allocate policy_data for all existing blkgs */ + while (cnt--) { + pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node); + if (!pd) { + ret = -ENOMEM; + goto out_free; + } + list_add_tail(&pd->alloc_node, &pds); + } + + /* + * Install the allocated pds. With @q bypassing, no new blkg + * should have been created while the queue lock was dropped. + */ + spin_lock_irq(q->queue_lock); + + list_for_each_entry(blkg, &q->blkg_list, q_node) { + if (WARN_ON(list_empty(&pds))) { + /* umm... this shouldn't happen, just abort */ + ret = -ENOMEM; + goto out_unlock; + } + pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node); + list_del_init(&pd->alloc_node); + + /* grab blkcg lock too while installing @pd on @blkg */ + spin_lock(&blkg->blkcg->lock); + + blkg->pd[pol->plid] = pd; + pd->blkg = blkg; + pol->pd_init_fn(blkg); + + spin_unlock(&blkg->blkcg->lock); + } + + __set_bit(pol->plid, q->blkcg_pols); + ret = 0; +out_unlock: + spin_unlock_irq(q->queue_lock); +out_free: + blk_queue_bypass_end(q); + list_for_each_entry_safe(pd, n, &pds, alloc_node) + kfree(pd); + return ret; } -EXPORT_SYMBOL_GPL(blkio_policy_register); +EXPORT_SYMBOL_GPL(blkcg_activate_policy); -void blkio_policy_unregister(struct blkio_policy_type *blkiop) +/** + * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue + * @q: request_queue of interest + * @pol: blkcg policy to deactivate + * + * Deactivate @pol on @q. Follows the same synchronization rules as + * blkcg_activate_policy(). + */ +void blkcg_deactivate_policy(struct request_queue *q, + const struct blkcg_policy *pol) { - spin_lock(&blkio_list_lock); - list_del_init(&blkiop->list); - spin_unlock(&blkio_list_lock); + struct blkcg_gq *blkg; + + if (!blkcg_policy_enabled(q, pol)) + return; + + blk_queue_bypass_start(q); + spin_lock_irq(q->queue_lock); + + __clear_bit(pol->plid, q->blkcg_pols); + + /* if no policy is left, no need for blkgs - shoot them down */ + if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS)) + blkg_destroy_all(q); + + list_for_each_entry(blkg, &q->blkg_list, q_node) { + /* grab blkcg lock too while removing @pd from @blkg */ + spin_lock(&blkg->blkcg->lock); + + if (pol->pd_exit_fn) + pol->pd_exit_fn(blkg); + + kfree(blkg->pd[pol->plid]); + blkg->pd[pol->plid] = NULL; + + spin_unlock(&blkg->blkcg->lock); + } + + spin_unlock_irq(q->queue_lock); + blk_queue_bypass_end(q); } -EXPORT_SYMBOL_GPL(blkio_policy_unregister); +EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); -static int __init init_cgroup_blkio(void) +/** + * blkcg_policy_register - register a blkcg policy + * @pol: blkcg policy to register + * + * Register @pol with blkcg core. Might sleep and @pol may be modified on + * successful registration. Returns 0 on success and -errno on failure. + */ +int blkcg_policy_register(struct blkcg_policy *pol) { - return cgroup_load_subsys(&blkio_subsys); + int i, ret; + + if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data))) + return -EINVAL; + + mutex_lock(&blkcg_pol_mutex); + + /* find an empty slot */ + ret = -ENOSPC; + for (i = 0; i < BLKCG_MAX_POLS; i++) + if (!blkcg_policy[i]) + break; + if (i >= BLKCG_MAX_POLS) + goto out_unlock; + + /* register and update blkgs */ + pol->plid = i; + blkcg_policy[i] = pol; + + /* everything is in place, add intf files for the new policy */ + if (pol->cftypes) + WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes)); + ret = 0; +out_unlock: + mutex_unlock(&blkcg_pol_mutex); + return ret; } +EXPORT_SYMBOL_GPL(blkcg_policy_register); -static void __exit exit_cgroup_blkio(void) +/** + * blkcg_policy_unregister - unregister a blkcg policy + * @pol: blkcg policy to unregister + * + * Undo blkcg_policy_register(@pol). Might sleep. + */ +void blkcg_policy_unregister(struct blkcg_policy *pol) { - cgroup_unload_subsys(&blkio_subsys); -} + mutex_lock(&blkcg_pol_mutex); -module_init(init_cgroup_blkio); -module_exit(exit_cgroup_blkio); -MODULE_LICENSE("GPL"); + if (WARN_ON(blkcg_policy[pol->plid] != pol)) + goto out_unlock; + + /* kill the intf files first */ + if (pol->cftypes) + cgroup_rm_cftypes(&blkio_subsys, pol->cftypes); + + /* unregister and update blkgs */ + blkcg_policy[pol->plid] = NULL; +out_unlock: + mutex_unlock(&blkcg_pol_mutex); +} +EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |