diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup.c | 180 | ||||
| -rw-r--r-- | block/blk-cgroup.h | 36 | ||||
| -rw-r--r-- | block/blk-core.c | 3 | ||||
| -rw-r--r-- | block/blk-exec.c | 2 | ||||
| -rw-r--r-- | block/blk-flush.c | 16 | ||||
| -rw-r--r-- | block/blk-lib.c | 82 | ||||
| -rw-r--r-- | block/blk-settings.c | 9 | ||||
| -rw-r--r-- | block/blk-sysfs.c | 3 | ||||
| -rw-r--r-- | block/blk-throttle.c | 313 | ||||
| -rw-r--r-- | block/blk.h | 20 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 202 | ||||
| -rw-r--r-- | block/elevator.c | 7 |
12 files changed, 633 insertions, 240 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 471fdcc5df8..e41cc6f2ccc 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -385,25 +385,40 @@ void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time, 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); +/* + * 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 *stats; + struct blkio_group_stats_cpu *stats_cpu; unsigned long flags; - spin_lock_irqsave(&blkg->stats_lock, flags); - stats = &blkg->stats; - stats->sectors += bytes >> 9; - blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction, - sync); - blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes, - direction, sync); - spin_unlock_irqrestore(&blkg->stats_lock, flags); + /* + * Disabling interrupts to provide mutual exclusion between two + * writes on same cpu. It probably is not needed for 64bit. Not + * optimizing that case yet. + */ + local_irq_save(flags); + + stats_cpu = this_cpu_ptr(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); @@ -438,6 +453,20 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction, } 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. + */ +int blkio_alloc_blkg_stats(struct blkio_group *blkg) +{ + /* 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); + void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, struct blkio_group *blkg, void *key, dev_t dev, enum blkio_policy_id plid) @@ -508,6 +537,30 @@ struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) } EXPORT_SYMBOL_GPL(blkiocg_lookup_group); +static void blkio_reset_stats_cpu(struct blkio_group *blkg) +{ + struct blkio_group_stats_cpu *stats_cpu; + int i, j, k; + /* + * 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. + * + * 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. + */ + 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; + } +} + static int blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val) { @@ -552,7 +605,11 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val) } #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; } @@ -598,6 +655,59 @@ static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t 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) @@ -609,9 +719,6 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, if (type == BLKIO_STAT_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, blkg->stats.time, cb, dev); - if (type == BLKIO_STAT_SECTORS) - return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, - blkg->stats.sectors, cb, dev); #ifdef CONFIG_DEBUG_BLK_CGROUP if (type == BLKIO_STAT_UNACCOUNTED_TIME) return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, @@ -1075,8 +1182,8 @@ static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft, } 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) + struct cftype *cft, struct cgroup_map_cb *cb, + enum stat_type type, bool show_total, bool pcpu) { struct blkio_group *blkg; struct hlist_node *n; @@ -1087,10 +1194,15 @@ static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg, if (blkg->dev) { if (!cftype_blkg_same_policy(cft, blkg)) continue; - spin_lock_irq(&blkg->stats_lock); - cgroup_total += blkio_get_stat(blkg, cb, blkg->dev, - type); - spin_unlock_irq(&blkg->stats_lock); + 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) @@ -1114,47 +1226,47 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, switch(name) { case BLKIO_PROP_time: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_TIME, 0); + BLKIO_STAT_TIME, 0, 0); case BLKIO_PROP_sectors: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_SECTORS, 0); + BLKIO_STAT_CPU_SECTORS, 0, 1); case BLKIO_PROP_io_service_bytes: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_SERVICE_BYTES, 1); + BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1); case BLKIO_PROP_io_serviced: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_SERVICED, 1); + 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); + 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); + BLKIO_STAT_WAIT_TIME, 1, 0); case BLKIO_PROP_io_merged: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_MERGED, 1); + BLKIO_STAT_MERGED, 1, 0); case BLKIO_PROP_io_queued: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_QUEUED, 1); + 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); + BLKIO_STAT_UNACCOUNTED_TIME, 0, 0); case BLKIO_PROP_dequeue: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_DEQUEUE, 0); + 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); + 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); + 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); + BLKIO_STAT_IDLE_TIME, 0, 0); case BLKIO_PROP_empty_time: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_EMPTY_TIME, 0); + BLKIO_STAT_EMPTY_TIME, 0, 0); #endif default: BUG(); @@ -1164,10 +1276,10 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, switch(name){ case BLKIO_THROTL_io_service_bytes: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_SERVICE_BYTES, 1); + BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1); case BLKIO_THROTL_io_serviced: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_SERVICED, 1); + BLKIO_STAT_CPU_SERVICED, 1, 1); default: BUG(); } diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index c774930cc20..26222679809 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -14,6 +14,7 @@ */ #include <linux/cgroup.h> +#include <linux/u64_stats_sync.h> enum blkio_policy_id { BLKIO_POLICY_PROP = 0, /* Proportional Bandwidth division */ @@ -36,10 +37,6 @@ enum stat_type { * request completion for IOs doen by this cgroup. This may not be * accurate when NCQ is turned on. */ BLKIO_STAT_SERVICE_TIME = 0, - /* Total bytes transferred */ - BLKIO_STAT_SERVICE_BYTES, - /* Total IOs serviced, post merge */ - BLKIO_STAT_SERVICED, /* Total time spent waiting in scheduler queue in ns */ BLKIO_STAT_WAIT_TIME, /* Number of IOs merged */ @@ -48,10 +45,9 @@ enum stat_type { BLKIO_STAT_QUEUED, /* All the single valued stats go below this */ BLKIO_STAT_TIME, - BLKIO_STAT_SECTORS, +#ifdef CONFIG_DEBUG_BLK_CGROUP /* Time not charged to this cgroup */ BLKIO_STAT_UNACCOUNTED_TIME, -#ifdef CONFIG_DEBUG_BLK_CGROUP BLKIO_STAT_AVG_QUEUE_SIZE, BLKIO_STAT_IDLE_TIME, BLKIO_STAT_EMPTY_TIME, @@ -60,6 +56,16 @@ enum stat_type { #endif }; +/* Per cpu stats */ +enum stat_type_cpu { + BLKIO_STAT_CPU_SECTORS, + /* Total bytes transferred */ + BLKIO_STAT_CPU_SERVICE_BYTES, + /* Total IOs serviced, post merge */ + BLKIO_STAT_CPU_SERVICED, + BLKIO_STAT_CPU_NR +}; + enum stat_sub_type { BLKIO_STAT_READ = 0, BLKIO_STAT_WRITE, @@ -116,11 +122,11 @@ struct blkio_cgroup { struct blkio_group_stats { /* total disk time and nr sectors dispatched by this group */ uint64_t time; - uint64_t sectors; - /* Time not charged to this cgroup */ - uint64_t unaccounted_time; uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL]; #ifdef CONFIG_DEBUG_BLK_CGROUP + /* Time not charged to this cgroup */ + uint64_t unaccounted_time; + /* Sum of number of IOs queued across all samples */ uint64_t avg_queue_size_sum; /* Count of samples taken for average */ @@ -145,6 +151,13 @@ struct blkio_group_stats { #endif }; +/* Per cpu blkio group stats */ +struct blkio_group_stats_cpu { + uint64_t sectors; + uint64_t stat_arr_cpu[BLKIO_STAT_CPU_NR][BLKIO_STAT_TOTAL]; + struct u64_stats_sync syncp; +}; + struct blkio_group { /* An rcu protected unique identifier for the group */ void *key; @@ -160,6 +173,8 @@ struct blkio_group { /* Need to serialize the stats in the case of reset/update */ spinlock_t stats_lock; struct blkio_group_stats stats; + /* Per cpu stats pointer */ + struct blkio_group_stats_cpu __percpu *stats_cpu; }; struct blkio_policy_node { @@ -295,6 +310,7 @@ extern struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk); extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, struct blkio_group *blkg, void *key, dev_t dev, enum blkio_policy_id plid); +extern int blkio_alloc_blkg_stats(struct blkio_group *blkg); extern int blkiocg_del_blkio_group(struct blkio_group *blkg); extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key); @@ -322,6 +338,8 @@ static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, struct blkio_group *blkg, void *key, dev_t dev, enum blkio_policy_id plid) {} +static inline int blkio_alloc_blkg_stats(struct blkio_group *blkg) { return 0; } + static inline int blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; } 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-exec.c b/block/blk-exec.c index 81e31819a59..8a0e7ec056e 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -56,7 +56,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, spin_lock_irq(q->queue_lock); __elv_add_request(q, rq, where); __blk_run_queue(q); - /* the queue is stopped so it won't be plugged+unplugged */ + /* the queue is stopped so it won't be run */ if (rq->cmd_type == REQ_TYPE_PM_RESUME) q->request_fn(q); spin_unlock_irq(q->queue_lock); diff --git a/block/blk-flush.c b/block/blk-flush.c index 6c9b5e189e6..bb21e4c36f7 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -212,13 +212,19 @@ static void flush_end_io(struct request *flush_rq, int error) } /* - * Moving a request silently to empty queue_head may stall the - * queue. Kick the queue in those cases. This function is called - * from request completion path and calling directly into - * request_fn may confuse the driver. Always use kblockd. + * Kick the queue to avoid stall for two cases: + * 1. Moving a request silently to empty queue_head may stall the + * queue. + * 2. When flush request is running in non-queueable queue, the + * queue is hold. Restart the queue after flush request is finished + * to avoid stall. + * This function is called from request completion path and calling + * directly into request_fn may confuse the driver. Always use + * kblockd. */ - if (queued) + if (queued || q->flush_queue_delayed) blk_run_queue_async(q); + q->flush_queue_delayed = 0; } /** diff --git a/block/blk-lib.c b/block/blk-lib.c index 25de73e4759..78e627e2581 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -9,17 +9,20 @@ #include "blk.h" -static void blkdev_discard_end_io(struct bio *bio, int err) -{ - if (err) { - if (err == -EOPNOTSUPP) - set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); - clear_bit(BIO_UPTODATE, &bio->bi_flags); - } +struct bio_batch { + atomic_t done; + unsigned long flags; + struct completion *wait; +}; - if (bio->bi_private) - complete(bio->bi_private); +static void bio_batch_end_io(struct bio *bio, int err) +{ + struct bio_batch *bb = bio->bi_private; + if (err && (err != -EOPNOTSUPP)) + clear_bit(BIO_UPTODATE, &bb->flags); + if (atomic_dec_and_test(&bb->done)) + complete(bb->wait); bio_put(bio); } @@ -41,6 +44,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, struct request_queue *q = bdev_get_queue(bdev); int type = REQ_WRITE | REQ_DISCARD; unsigned int max_discard_sectors; + struct bio_batch bb; struct bio *bio; int ret = 0; @@ -67,7 +71,11 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, type |= REQ_SECURE; } - while (nr_sects && !ret) { + atomic_set(&bb.done, 1); + bb.flags = 1 << BIO_UPTODATE; + bb.wait = &wait; + + while (nr_sects) { bio = bio_alloc(gfp_mask, 1); if (!bio) { ret = -ENOMEM; @@ -75,9 +83,9 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, } bio->bi_sector = sector; - bio->bi_end_io = blkdev_discard_end_io; + bio->bi_end_io = bio_batch_end_io; bio->bi_bdev = bdev; - bio->bi_private = &wait; + bio->bi_private = &bb; if (nr_sects > max_discard_sectors) { bio->bi_size = max_discard_sectors << 9; @@ -88,45 +96,21 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, nr_sects = 0; } - bio_get(bio); + atomic_inc(&bb.done); submit_bio(type, bio); + } + /* Wait for bios in-flight */ + if (!atomic_dec_and_test(&bb.done)) wait_for_completion(&wait); - if (bio_flagged(bio, BIO_EOPNOTSUPP)) - ret = -EOPNOTSUPP; - else if (!bio_flagged(bio, BIO_UPTODATE)) - ret = -EIO; - bio_put(bio); - } + if (!test_bit(BIO_UPTODATE, &bb.flags)) + ret = -EIO; return ret; } EXPORT_SYMBOL(blkdev_issue_discard); -struct bio_batch -{ - atomic_t done; - unsigned long flags; - struct completion *wait; -}; - -static void bio_batch_end_io(struct bio *bio, int err) -{ - struct bio_batch *bb = bio->bi_private; - - if (err) { - if (err == -EOPNOTSUPP) - set_bit(BIO_EOPNOTSUPP, &bb->flags); - else - clear_bit(BIO_UPTODATE, &bb->flags); - } - if (bb) - if (atomic_dec_and_test(&bb->done)) - complete(bb->wait); - bio_put(bio); -} - /** * blkdev_issue_zeroout - generate number of zero filed write bios * @bdev: blockdev to issue @@ -151,7 +135,6 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, bb.flags = 1 << BIO_UPTODATE; bb.wait = &wait; -submit: ret = 0; while (nr_sects != 0) { bio = bio_alloc(gfp_mask, @@ -168,9 +151,6 @@ submit: while (nr_sects != 0) { sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects); - if (sz == 0) - /* bio has maximum size possible */ - break; ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0); nr_sects -= ret >> 9; sector += ret >> 9; @@ -190,16 +170,6 @@ submit: /* One of bios in the batch was completed with error.*/ ret = -EIO; - if (ret) - goto out; - - if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) { - ret = -EOPNOTSUPP; - goto out; - } - if (nr_sects != 0) - goto submit; -out: return ret; } EXPORT_SYMBOL(blkdev_issue_zeroout); diff --git a/block/blk-settings.c b/block/blk-settings.c index 1fa76929359..fa1eb0449a0 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -120,7 +120,7 @@ void blk_set_default_limits(struct queue_limits *lim) lim->discard_granularity = 0; lim->discard_alignment = 0; lim->discard_misaligned = 0; - lim->discard_zeroes_data = -1; + lim->discard_zeroes_data = 1; lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); lim->alignment_offset = 0; @@ -166,6 +166,7 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) blk_set_default_limits(&q->limits); blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS); + q->limits.discard_zeroes_data = 0; /* * by default assume old behaviour and bounce for any highmem page @@ -790,6 +791,12 @@ void blk_queue_flush(struct request_queue *q, unsigned int flush) } EXPORT_SYMBOL_GPL(blk_queue_flush); +void blk_queue_flush_queueable(struct request_queue *q, bool queueable) +{ + q->flush_not_queueable = !queueable; +} +EXPORT_SYMBOL_GPL(blk_queue_flush_queueable); + static int __init blk_settings_init(void) { blk_max_low_pfn = max_low_pfn - 1; diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index bd236313f35..d935bd859c8 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -152,7 +152,8 @@ static ssize_t queue_discard_granularity_show(struct request_queue *q, char *pag static ssize_t queue_discard_max_show(struct request_queue *q, char *page) { - return queue_var_show(q->limits.max_discard_sectors << 9, page); + return sprintf(page, "%llu\n", + (unsigned long long)q->limits.max_discard_sectors << 9); } static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 252a81a306f..a62be8d0dc1 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -78,6 +78,8 @@ struct throtl_grp { /* Some throttle limits got updated for the group */ int limits_changed; + + struct rcu_head rcu_head; }; struct throtl_data @@ -88,7 +90,7 @@ struct throtl_data /* service tree for active throtl groups */ struct throtl_rb_root tg_service_tree; - struct throtl_grp root_tg; + struct throtl_grp *root_tg; struct request_queue *queue; /* Total Number of queued bios on READ and WRITE lists */ @@ -151,56 +153,44 @@ static inline struct throtl_grp *throtl_ref_get_tg(struct throtl_grp *tg) return tg; } -static void throtl_put_tg(struct throtl_grp *tg) +static void throtl_free_tg(struct rcu_head *head) { - BUG_ON(atomic_read(&tg->ref) <= 0); - if (!atomic_dec_and_test(&tg->ref)) - return; + struct throtl_grp *tg; + + tg = container_of(head, struct throtl_grp, rcu_head); + free_percpu(tg->blkg.stats_cpu); kfree(tg); } -static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, - struct blkio_cgroup *blkcg) +static void throtl_put_tg(struct throtl_grp *tg) { - struct throtl_grp *tg = NULL; - void *key = td; - struct backing_dev_info *bdi = &td->queue->backing_dev_info; - unsigned int major, minor; + BUG_ON(atomic_read(&tg->ref) <= 0); + if (!atomic_dec_and_test(&tg->ref)) + return; /* - * TODO: Speed up blkiocg_lookup_group() by maintaining a radix - * tree of blkg (instead of traversing through hash list all - * the time. + * A group is freed in rcu manner. But having an rcu lock does not + * mean that one can access all the fields of blkg and assume these + * are valid. For example, don't try to follow throtl_data and + * request queue links. + * + * Having a reference to blkg under an rcu allows acess to only + * values local to groups like group stats and group rate limits */ + call_rcu(&tg->rcu_head, throtl_free_tg); +} - /* - * This is the common case when there are no blkio cgroups. - * Avoid lookup in this case - */ - if (blkcg == &blkio_root_cgroup) - tg = &td->root_tg; - else - tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key)); - - /* Fill in device details for root group */ - 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; - +static void throtl_init_group(struct throtl_grp *tg) +{ INIT_HLIST_NODE(&tg->tg_node); RB_CLEAR_NODE(&tg->rb_node); bio_list_init(&tg->bio_lists[0]); bio_list_init(&tg->bio_lists[1]); - td->limits_changed = false; + tg->limits_changed = false; + + /* Practically unlimited BW */ + tg->bps[0] = tg->bps[1] = -1; + tg->iops[0] = tg->iops[1] = -1; /* * Take the initial reference that will be released on destroy @@ -209,33 +199,181 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, * exit or cgroup deletion path depending on who is exiting first. */ atomic_set(&tg->ref, 1); +} + +/* Should be called with rcu read lock held (needed for blkcg) */ +static void +throtl_add_group_to_td_list(struct throtl_data *td, struct throtl_grp *tg) +{ + hlist_add_head(&tg->tg_node, &td->tg_list); + td->nr_undestroyed_grps++; +} + +static void +__throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg) +{ + struct backing_dev_info *bdi = &td->queue->backing_dev_info; + unsigned int major, minor; + + if (!tg || tg->blkg.dev) + return; + + /* + * Fill in device details for a group which might not have been + * filled at group creation time as queue was being instantiated + * and driver had not attached a device yet + */ + if (bdi->dev && dev_name(bdi->dev)) { + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); + tg->blkg.dev = MKDEV(major, minor); + } +} + +/* + * Should be called with without queue lock held. Here queue lock will be + * taken rarely. It will be taken only once during life time of a group + * if need be + */ +static void +throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg) +{ + if (!tg || tg->blkg.dev) + return; + + spin_lock_irq(td->queue->queue_lock); + __throtl_tg_fill_dev_details(td, tg); + spin_unlock_irq(td->queue->queue_lock); +} + +static void throtl_init_add_tg_lists(struct throtl_data *td, + struct throtl_grp *tg, struct blkio_cgroup *blkcg) +{ + __throtl_tg_fill_dev_details(td, 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->blkg.dev, 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); - hlist_add_head(&tg->tg_node, &td->tg_list); - td->nr_undestroyed_grps++; -done: + 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; + int ret; + + tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node); + if (!tg) + return NULL; + + ret = blkio_alloc_blkg_stats(&tg->blkg); + + if (ret) { + kfree(tg); + return NULL; + } + + throtl_init_group(tg); return tg; } -static struct throtl_grp * throtl_get_tg(struct throtl_data *td) +static struct +throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg) { struct throtl_grp *tg = NULL; + void *key = td; + + /* + * This is the common case when there are no blkio cgroups. + * Avoid lookup in this case + */ + if (blkcg == &blkio_root_cgroup) + tg = td->root_tg; + else + tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key)); + + __throtl_tg_fill_dev_details(td, tg); + 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, *__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 = &td->root_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; } @@ -544,6 +682,12 @@ static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg, return 0; } +static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) { + if (tg->bps[rw] == -1 && tg->iops[rw] == -1) + return 1; + return 0; +} + /* * Returns whether one can dispatch a bio or not. Also returns approx number * of jiffies to wait before this bio is with-in IO rate and can be dispatched @@ -608,10 +752,6 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) tg->bytes_disp[rw] += bio->bi_size; tg->io_disp[rw]++; - /* - * TODO: This will take blkg->stats_lock. Figure out a way - * to avoid this cost. - */ blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, sync); } @@ -989,15 +1129,51 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) struct throtl_grp *tg; struct bio *bio = *biop; bool rw = bio_data_dir(bio), update_disptime = true; + struct blkio_cgroup *blkcg; if (bio->bi_rw & REQ_THROTTLED) { bio->bi_rw &= ~REQ_THROTTLED; return 0; } + /* + * A throtl_grp pointer retrieved under rcu can be used to access + * basic fields like stats and io rates. If a group has no rules, + * just update the dispatch stats in lockless manner and return. + */ + + rcu_read_lock(); + blkcg = task_blkio_cgroup(current); + tg = throtl_find_tg(td, blkcg); + if (tg) { + throtl_tg_fill_dev_details(td, tg); + + if (tg_no_rule_group(tg, rw)) { + blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, + rw, bio->bi_rw & REQ_SYNC); + rcu_read_unlock(); + return 0; + } + } + rcu_read_unlock(); + + /* + * Either group has not been allocated yet or it is not an unlimited + * IO group + */ + 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 @@ -1060,39 +1236,24 @@ int blk_throtl_init(struct request_queue *q) INIT_HLIST_HEAD(&td->tg_list); td->tg_service_tree = THROTL_RB_ROOT; td->limits_changed = false; + INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work); - /* Init root group */ - tg = &td->root_tg; - INIT_HLIST_NODE(&tg->tg_node); - RB_CLEAR_NODE(&tg->rb_node); - bio_list_init(&tg->bio_lists[0]); - bio_list_init(&tg->bio_lists[1]); - - /* Practically unlimited BW */ - tg->bps[0] = tg->bps[1] = -1; - tg->iops[0] = tg->iops[1] = -1; - td->limits_changed = false; + /* alloc and Init root group. */ + td->queue = q; + tg = throtl_alloc_tg(td); - /* - * Set root group reference to 2. One reference will be dropped when - * all groups on tg_list are being deleted during queue exit. Other - * reference will remain there as we don't want to delete this group - * as it is statically allocated and gets destroyed when throtl_data - * goes away. - */ - atomic_set(&tg->ref, 2); - hlist_add_head(&tg->tg_node, &td->tg_list); - td->nr_undestroyed_grps++; + if (!tg) { + kfree(td); + return -ENOMEM; + } - INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work); + td->root_tg = tg; rcu_read_lock(); - blkiocg_add_blkio_group(&blkio_root_cgroup, &tg->blkg, (void *)td, - 0, BLKIO_POLICY_THROTL); + throtl_init_add_tg_lists(td, tg, &blkio_root_cgroup); rcu_read_unlock(); /* Attach throtl data to request queue */ - td->queue = q; q->td = td; return 0; } diff --git a/block/blk.h b/block/blk.h index 4df474d37e6..d6586287adc 100644 --- a/block/blk.h +++ b/block/blk.h @@ -62,6 +62,26 @@ static inline struct request *__elv_next_request(struct request_queue *q) return rq; } + /* + * Flush request is running and flush request isn't queueable + * in the drive, we can hold the queue till flush request is + * finished. Even we don't do this, driver can't dispatch next + * requests and will requeue them. And this can improve + * throughput too. For example, we have request flush1, write1, + * flush 2. flush1 is dispatched, then queue is hold, write1 + * isn't inserted to queue. After flush1 is finished, flush2 + * will be dispatched. Since disk cache is already clean, + * flush2 will be finished very soon, so looks like flush2 is + * folded to flush1. + * Since the queue is hold, a flag is set to indicate the queue + * should be restarted later. Please see flush_end_io() for + * details. + */ + if (q->flush_pending_idx != q->flush_running_idx && + !queue_flush_queueable(q)) { + q->flush_queue_delayed = 1; + return NULL; + } if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) || !q->elevator->ops->elevator_dispatch_fn(q, 0)) return NULL; diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index ab7a9e6a9b1..d646b279c8b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -300,7 +300,9 @@ struct cfq_data { /* List of cfq groups being managed on this device*/ struct hlist_head cfqg_list; - struct rcu_head rcu; + + /* Number of groups which are on blkcg->blkg_list */ + unsigned int nr_blkcg_linked_grps; }; static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); @@ -1014,28 +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, int create) +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 || !create) - 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, ret; + 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; @@ -1049,43 +1070,94 @@ static struct cfq_group * cfq_find_alloc_cfqg(struct cfq_data *cfqd, */ cfqg->ref = 1; + ret = blkio_alloc_blkg_stats(&cfqg->blkg); + if (ret) { + kfree(cfqg); + return NULL; + } + + 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); - - 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; } /* - * Search for the cfq group current task belongs to. If create = 1, then also - * create the cfq group if it does not exist. request_queue lock must be held. + * Search for the cfq group current task belongs to. request_queue lock must + * be held. */ -static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) +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_alloc_cfqg(cfqd, blkcg, create); - if (!cfqg && create) + 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); + + /* + * 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; } @@ -1118,6 +1190,7 @@ static void cfq_put_cfqg(struct cfq_group *cfqg) return; for_each_cfqg_st(cfqg, i, j, st) BUG_ON(!RB_EMPTY_ROOT(&st->rb)); + free_percpu(cfqg->blkg.stats_cpu); kfree(cfqg); } @@ -1176,7 +1249,7 @@ void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) } #else /* GROUP_IOSCHED */ -static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) +static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) { return &cfqd->root_group; } @@ -2911,7 +2984,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_group *cfqg; retry: - cfqg = cfq_get_cfqg(cfqd, 1); + cfqg = cfq_get_cfqg(cfqd); cic = cfq_cic_lookup(cfqd, ioc); /* cic always exists here */ cfqq = cic_to_cfqq(cic, is_sync); @@ -3815,15 +3888,11 @@ static void cfq_put_async_queues(struct cfq_data *cfqd) cfq_put_queue(cfqd->async_idle_cfqq); } -static void cfq_cfqd_free(struct rcu_head *head) -{ - kfree(container_of(head, struct cfq_data, rcu)); -} - static void cfq_exit_queue(struct elevator_queue *e) { struct cfq_data *cfqd = e->elevator_data; struct request_queue *q = cfqd->queue; + bool wait = false; cfq_shutdown_timer_wq(cfqd); @@ -3842,7 +3911,13 @@ static void cfq_exit_queue(struct elevator_queue *e) cfq_put_async_queues(cfqd); cfq_release_cfq_groups(cfqd); - cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg); + + /* + * If there are groups which we could not unlink from blkcg list, + * wait for a rcu period for them to be freed. + */ + if (cfqd->nr_blkcg_linked_grps) + wait = true; spin_unlock_irq(q->queue_lock); @@ -3852,8 +3927,20 @@ static void cfq_exit_queue(struct elevator_queue *e) ida_remove(&cic_index_ida, cfqd->cic_index); spin_unlock(&cic_index_lock); - /* Wait for cfqg->blkg->key accessors to exit their grace periods. */ - call_rcu(&cfqd->rcu, cfq_cfqd_free); + /* + * Wait for cfqg->blkg->key accessors to exit their grace periods. + * Do this wait only if there are other unlinked groups out + * there. This can happen if cgroup deletion path claimed the + * responsibility of cleaning up a group before queue cleanup code + * get to the group. + * + * Do not call synchronize_rcu() unconditionally as there are drivers + * which create/delete request queue hundreds of times during scan/boot + * and synchronize_rcu() can take significant time and slow down boot. + */ + if (wait) + synchronize_rcu(); + kfree(cfqd); } static int cfq_alloc_cic_index(void) @@ -3909,14 +3996,29 @@ static void *cfq_init_queue(struct request_queue *q) #ifdef CONFIG_CFQ_GROUP_IOSCHED /* - * Take a reference to root group which we never drop. This is just - * to make sure that cfq_put_cfqg() does not try to kfree root group + * Set root group reference to 2. One reference will be dropped when + * all groups on cfqd->cfqg_list are being deleted during queue exit. + * Other reference will remain there as we don't want to delete this + * group as it is statically allocated and gets destroyed when + * throtl_data goes away. */ - cfqg->ref = 1; + cfqg->ref = 2; + + if (blkio_alloc_blkg_stats(&cfqg->blkg)) { + kfree(cfqg); + kfree(cfqd); + return NULL; + } + rcu_read_lock(); + cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd, 0); rcu_read_unlock(); + cfqd->nr_blkcg_linked_grps++; + + /* Add group on cfqd->cfqg_list */ + hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); #endif /* * Not strictly needed (since RB_ROOT just clears the node and we diff --git a/block/elevator.c b/block/elevator.c index 45ca1e34f58..2a0b653c90f 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -155,13 +155,8 @@ static struct elevator_type *elevator_get(const char *name) e = elevator_find(name); if (!e) { - char elv[ELV_NAME_MAX + strlen("-iosched")]; - spin_unlock(&elv_list_lock); - - snprintf(elv, sizeof(elv), "%s-iosched", name); - - request_module("%s", elv); + request_module("%s-iosched", name); spin_lock(&elv_list_lock); e = elevator_find(name); } |