diff options
| -rw-r--r-- | block/blk-cgroup.c | 136 | ||||
| -rw-r--r-- | block/blk-cgroup.h | 4 | ||||
| -rw-r--r-- | block/cfq.h | 10 |
3 files changed, 51 insertions, 99 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index cad5f15cf49b..e9e3b038c702 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -620,32 +620,6 @@ out: } EXPORT_SYMBOL_GPL(blkg_lookup_create); -static void __blkiocg_del_blkio_group(struct blkio_group *blkg) -{ - hlist_del_init_rcu(&blkg->blkcg_node); -} - -/* - * 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 = blkg->blkcg; - unsigned long flags; - int ret = 1; - - 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); - - return ret; -} -EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group); - /* called under rcu_read_lock(). */ struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg, struct request_queue *q) @@ -663,12 +637,16 @@ EXPORT_SYMBOL_GPL(blkg_lookup); static void blkg_destroy(struct blkio_group *blkg) { struct request_queue *q = blkg->q; + struct blkio_cgroup *blkcg = blkg->blkcg; lockdep_assert_held(q->queue_lock); + lockdep_assert_held(&blkcg->lock); /* Something wrong if we are trying to remove same group twice */ WARN_ON_ONCE(list_empty(&blkg->q_node)); + WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); list_del_init(&blkg->q_node); + hlist_del_init_rcu(&blkg->blkcg_node); WARN_ON_ONCE(q->nr_blkgs <= 0); q->nr_blkgs--; @@ -713,45 +691,33 @@ void update_root_blkg_pd(struct request_queue *q, enum blkio_policy_id plid) } EXPORT_SYMBOL_GPL(update_root_blkg_pd); +/** + * blkg_destroy_all - destroy all blkgs associated with a request_queue + * @q: request_queue of interest + * @destroy_root: whether to destroy root blkg or not + * + * Destroy blkgs associated with @q. If @destroy_root is %true, all are + * destroyed; otherwise, root blkg is left alone. + */ void blkg_destroy_all(struct request_queue *q, bool destroy_root) { struct blkio_group *blkg, *n; - while (true) { - bool done = true; - - spin_lock_irq(q->queue_lock); - - list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { - /* skip root? */ - if (!destroy_root && blkg->blkcg == &blkio_root_cgroup) - continue; - - /* - * If cgroup removal path got to blk_group first - * and removed it from cgroup list, then it will - * take care of destroying cfqg also. - */ - if (!blkiocg_del_blkio_group(blkg)) - blkg_destroy(blkg); - else - done = false; - } + spin_lock_irq(q->queue_lock); - spin_unlock_irq(q->queue_lock); + list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { + struct blkio_cgroup *blkcg = blkg->blkcg; - /* - * Group list may not be empty if we raced cgroup removal - * and lost. cgroup removal is guaranteed to make forward - * progress and retrying after a while is enough. This - * ugliness is scheduled to be removed after locking - * update. - */ - if (done) - break; + /* skip root? */ + if (!destroy_root && blkg->blkcg == &blkio_root_cgroup) + continue; - msleep(10); /* just some random duration I like */ + spin_lock(&blkcg->lock); + blkg_destroy(blkg); + spin_unlock(&blkcg->lock); } + + spin_unlock_irq(q->queue_lock); } EXPORT_SYMBOL_GPL(blkg_destroy_all); @@ -1600,45 +1566,45 @@ static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup) ARRAY_SIZE(blkio_files)); } +/** + * blkiocg_pre_destroy - cgroup pre_destroy callback + * @subsys: cgroup subsys + * @cgroup: cgroup of interest + * + * This function is called when @cgroup is about to go away and responsible + * for shooting down all blkgs associated with @cgroup. blkgs should be + * removed while holding both q and blkcg locks. As blkcg lock is nested + * inside q lock, this function performs reverse double lock dancing. + * + * This is the blkcg counterpart of ioc_release_fn(). + */ static int blkiocg_pre_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) { struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); - unsigned long flags; - struct blkio_group *blkg; - struct request_queue *q; rcu_read_lock(); + spin_lock_irq(&blkcg->lock); - do { - spin_lock_irqsave(&blkcg->lock, flags); + while (!hlist_empty(&blkcg->blkg_list)) { + struct blkio_group *blkg = hlist_entry(blkcg->blkg_list.first, + struct blkio_group, blkcg_node); + struct request_queue *q = rcu_dereference(blkg->q); - if (hlist_empty(&blkcg->blkg_list)) { - spin_unlock_irqrestore(&blkcg->lock, flags); - break; + if (spin_trylock(q->queue_lock)) { + blkg_destroy(blkg); + spin_unlock(q->queue_lock); + } else { + spin_unlock_irq(&blkcg->lock); + rcu_read_unlock(); + cpu_relax(); + rcu_read_lock(); + spin_lock(&blkcg->lock); } + } - blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group, - blkcg_node); - q = rcu_dereference(blkg->q); - __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); - spin_lock_irqsave(q->queue_lock, flags); - blkg_destroy(blkg); - spin_unlock_irqrestore(q->queue_lock, flags); - spin_unlock(&blkio_list_lock); - } while (1); - + spin_unlock_irq(&blkcg->lock); rcu_read_unlock(); - return 0; } diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 6e8ee86a2870..df73040a6a5f 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -380,7 +380,6 @@ static inline void blkiocg_set_start_empty_time(struct blkio_group *blkg, extern struct blkio_cgroup blkio_root_cgroup; extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup); extern struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk); -extern int blkiocg_del_blkio_group(struct blkio_group *blkg); extern struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg, struct request_queue *q); struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg, @@ -416,9 +415,6 @@ cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; } static inline struct blkio_cgroup * task_blkio_cgroup(struct task_struct *tsk) { return NULL; } -static inline int -blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; } - static inline struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg, void *key) { return NULL; } static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg, diff --git a/block/cfq.h b/block/cfq.h index 5584e1b63ca8..c8b15ef57e5d 100644 --- a/block/cfq.h +++ b/block/cfq.h @@ -79,11 +79,6 @@ static inline void cfq_blkiocg_update_completion_stats(struct blkio_group *blkg, direction, sync); } -static inline int cfq_blkiocg_del_blkio_group(struct blkio_group *blkg) -{ - return blkiocg_del_blkio_group(blkg); -} - #else /* CFQ_GROUP_IOSCHED */ static inline void cfq_blkiocg_update_io_add_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, @@ -119,10 +114,5 @@ static inline void cfq_blkiocg_update_completion_stats(struct blkio_group *blkg, struct blkio_policy_type *pol, uint64_t start_time, uint64_t io_start_time, bool direction, bool sync) { } -static inline int cfq_blkiocg_del_blkio_group(struct blkio_group *blkg) -{ - return 0; -} - #endif /* CFQ_GROUP_IOSCHED */ #endif |