diff options
| -rw-r--r-- | block/blk-core.c | 3 | ||||
| -rw-r--r-- | block/blk-throttle.c | 141 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 128 |
3 files changed, 205 insertions, 67 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 3fe00a14822..9e8e297374b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1550,7 +1550,8 @@ static inline void __generic_make_request(struct bio *bio) goto end_io; } - blk_throtl_bio(q, &bio); + if (blk_throtl_bio(q, &bio)) + goto end_io; /* * If bio = NULL, bio has been throttled and will be submitted diff --git a/block/blk-throttle.c b/block/blk-throttle.c index fa9a900c125..c201967b33c 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -188,8 +188,40 @@ throtl_add_group_to_td_list(struct throtl_data *td, struct throtl_grp *tg) td->nr_undestroyed_grps++; } -static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, - struct blkio_cgroup *blkcg) +static void throtl_init_add_tg_lists(struct throtl_data *td, + struct throtl_grp *tg, struct blkio_cgroup *blkcg) +{ + struct backing_dev_info *bdi = &td->queue->backing_dev_info; + unsigned int major, minor; + + /* Add group onto cgroup list */ + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); + blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td, + MKDEV(major, minor), BLKIO_POLICY_THROTL); + + tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev); + tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev); + tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev); + tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev); + + throtl_add_group_to_td_list(td, tg); +} + +/* Should be called without queue lock and outside of rcu period */ +static struct throtl_grp *throtl_alloc_tg(struct throtl_data *td) +{ + struct throtl_grp *tg = NULL; + + tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node); + if (!tg) + return NULL; + + throtl_init_group(tg); + return tg; +} + +static struct +throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg) { struct throtl_grp *tg = NULL; void *key = td; @@ -197,12 +229,6 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, unsigned int major, minor; /* - * TODO: Speed up blkiocg_lookup_group() by maintaining a radix - * tree of blkg (instead of traversing through hash list all - * the time. - */ - - /* * This is the common case when there are no blkio cgroups. * Avoid lookup in this case */ @@ -215,43 +241,83 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); tg->blkg.dev = MKDEV(major, minor); - goto done; } - if (tg) - goto done; - - tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node); - if (!tg) - goto done; - - throtl_init_group(tg); - - /* Add group onto cgroup list */ - sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); - blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td, - MKDEV(major, minor), BLKIO_POLICY_THROTL); - - tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev); - tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev); - tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev); - tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev); - - throtl_add_group_to_td_list(td, tg); -done: return tg; } +/* + * This function returns with queue lock unlocked in case of error, like + * request queue is no more + */ static struct throtl_grp * throtl_get_tg(struct throtl_data *td) { - struct throtl_grp *tg = NULL; + struct throtl_grp *tg = NULL, *__tg = NULL; struct blkio_cgroup *blkcg; + struct request_queue *q = td->queue; rcu_read_lock(); blkcg = task_blkio_cgroup(current); - tg = throtl_find_alloc_tg(td, blkcg); - if (!tg) + tg = throtl_find_tg(td, blkcg); + if (tg) { + rcu_read_unlock(); + return tg; + } + + /* + * Need to allocate a group. Allocation of group also needs allocation + * of per cpu stats which in-turn takes a mutex() and can block. Hence + * we need to drop rcu lock and queue_lock before we call alloc + * + * Take the request queue reference to make sure queue does not + * go away once we return from allocation. + */ + blk_get_queue(q); + rcu_read_unlock(); + spin_unlock_irq(q->queue_lock); + + tg = throtl_alloc_tg(td); + /* + * We might have slept in group allocation. Make sure queue is not + * dead + */ + if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { + blk_put_queue(q); + if (tg) + kfree(tg); + + return ERR_PTR(-ENODEV); + } + blk_put_queue(q); + + /* Group allocated and queue is still alive. take the lock */ + spin_lock_irq(q->queue_lock); + + /* + * Initialize the new group. After sleeping, read the blkcg again. + */ + rcu_read_lock(); + blkcg = task_blkio_cgroup(current); + + /* + * If some other thread already allocated the group while we were + * not holding queue lock, free up the group + */ + __tg = throtl_find_tg(td, blkcg); + + if (__tg) { + kfree(tg); + rcu_read_unlock(); + return __tg; + } + + /* Group allocation failed. Account the IO to root group */ + if (!tg) { tg = &td->root_tg; + return tg; + } + + throtl_init_add_tg_lists(td, tg, blkcg); rcu_read_unlock(); return tg; } @@ -1014,6 +1080,15 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) spin_lock_irq(q->queue_lock); tg = throtl_get_tg(td); + if (IS_ERR(tg)) { + if (PTR_ERR(tg) == -ENODEV) { + /* + * Queue is gone. No queue lock held here. + */ + return -ENODEV; + } + } + if (tg->nr_queued[rw]) { /* * There is already another bio queued in same dir. No diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index e2e6719832e..606020fe93f 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1016,28 +1016,47 @@ void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, cfqg->needs_update = true; } -static struct cfq_group * cfq_find_alloc_cfqg(struct cfq_data *cfqd, - struct blkio_cgroup *blkcg) +static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, + struct cfq_group *cfqg, struct blkio_cgroup *blkcg) { - struct cfq_group *cfqg = NULL; - void *key = cfqd; - int i, j; - struct cfq_rb_root *st; struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; unsigned int major, minor; - cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); - if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { + /* + * Add group onto cgroup list. It might happen that bdi->dev is + * not initialized yet. Initialize this new group without major + * and minor info and this info will be filled in once a new thread + * comes for IO. + */ + if (bdi->dev) { sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); - cfqg->blkg.dev = MKDEV(major, minor); - goto done; - } - if (cfqg) - goto done; + cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, + (void *)cfqd, MKDEV(major, minor)); + } else + cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, + (void *)cfqd, 0); + + cfqd->nr_blkcg_linked_grps++; + cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); + + /* Add group on cfqd list */ + hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); +} + +/* + * Should be called from sleepable context. No request queue lock as per + * cpu stats are allocated dynamically and alloc_percpu needs to be called + * from sleepable context. + */ +static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) +{ + struct cfq_group *cfqg = NULL; + int i, j; + struct cfq_rb_root *st; cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); if (!cfqg) - goto done; + return NULL; for_each_cfqg_st(cfqg, i, j, st) *st = CFQ_RB_ROOT; @@ -1050,28 +1069,31 @@ static struct cfq_group * cfq_find_alloc_cfqg(struct cfq_data *cfqd, * or cgroup deletion path depending on who is exiting first. */ cfqg->ref = 1; + return cfqg; +} + +static struct cfq_group * +cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) +{ + struct cfq_group *cfqg = NULL; + void *key = cfqd; + struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; + unsigned int major, minor; /* - * Add group onto cgroup list. It might happen that bdi->dev is - * not initialized yet. Initialize this new group without major - * and minor info and this info will be filled in once a new thread - * comes for IO. See code above. + * This is the common case when there are no blkio cgroups. + * Avoid lookup in this case */ - if (bdi->dev) { - sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); - cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd, - MKDEV(major, minor)); - } else - cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd, - 0); - - cfqd->nr_blkcg_linked_grps++; - cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); + if (blkcg == &blkio_root_cgroup) + cfqg = &cfqd->root_group; + else + cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); - /* Add group on cfqd list */ - hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); + if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); + cfqg->blkg.dev = MKDEV(major, minor); + } -done: return cfqg; } @@ -1082,13 +1104,53 @@ done: static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) { struct blkio_cgroup *blkcg; - struct cfq_group *cfqg = NULL; + struct cfq_group *cfqg = NULL, *__cfqg = NULL; + struct request_queue *q = cfqd->queue; + + rcu_read_lock(); + blkcg = task_blkio_cgroup(current); + cfqg = cfq_find_cfqg(cfqd, blkcg); + if (cfqg) { + rcu_read_unlock(); + return cfqg; + } + + /* + * Need to allocate a group. Allocation of group also needs allocation + * of per cpu stats which in-turn takes a mutex() and can block. Hence + * we need to drop rcu lock and queue_lock before we call alloc. + * + * Not taking any queue reference here and assuming that queue is + * around by the time we return. CFQ queue allocation code does + * the same. It might be racy though. + */ + + rcu_read_unlock(); + spin_unlock_irq(q->queue_lock); + + cfqg = cfq_alloc_cfqg(cfqd); + + spin_lock_irq(q->queue_lock); rcu_read_lock(); blkcg = task_blkio_cgroup(current); - cfqg = cfq_find_alloc_cfqg(cfqd, blkcg); + + /* + * If some other thread already allocated the group while we were + * not holding queue lock, free up the group + */ + __cfqg = cfq_find_cfqg(cfqd, blkcg); + + if (__cfqg) { + kfree(cfqg); + rcu_read_unlock(); + return __cfqg; + } + if (!cfqg) cfqg = &cfqd->root_group; + + cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); rcu_read_unlock(); return cfqg; } |