From: Goldwyn Rodrigues <[email protected]> The RAID1 driver would bail with EAGAIN in case of: + I/O has to wait for a barrier + array is frozen + Area is suspended + There are too many pending I/O that it will be queued.
To facilitate error for wait barriers, wait_barrier() is returning bool. True in case if there was a wait (or is not required). False in case a wait was required, but was not performed. Signed-off-by: Goldwyn Rodrigues <[email protected]> --- drivers/md/raid1.c | 88 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 68 insertions(+), 20 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index f3f3e40dc9d8..37ec283e67af 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -891,8 +891,9 @@ static void lower_barrier(struct r1conf *conf, sector_t sector_nr) wake_up(&conf->wait_barrier); } -static void _wait_barrier(struct r1conf *conf, int idx) +static bool _wait_barrier(struct r1conf *conf, int idx, bool nowait) { + bool ret = true; /* * We need to increase conf->nr_pending[idx] very early here, * then raise_barrier() can be blocked when it waits for @@ -923,7 +924,7 @@ static void _wait_barrier(struct r1conf *conf, int idx) */ if (!READ_ONCE(conf->array_frozen) && !atomic_read(&conf->barrier[idx])) - return; + return ret; /* * After holding conf->resync_lock, conf->nr_pending[idx] @@ -941,18 +942,29 @@ static void _wait_barrier(struct r1conf *conf, int idx) */ wake_up(&conf->wait_barrier); /* Wait for the barrier in same barrier unit bucket to drop. */ - wait_event_lock_irq(conf->wait_barrier, - !conf->array_frozen && - !atomic_read(&conf->barrier[idx]), - conf->resync_lock); + if (conf->array_frozen || atomic_read(&conf->barrier[idx])) { + if (nowait) { + ret = false; + goto dec_waiting; + } else { + wait_event_lock_irq(conf->wait_barrier, + !conf->array_frozen && + !atomic_read(&conf->barrier[idx]), + conf->resync_lock); + } + } atomic_inc(&conf->nr_pending[idx]); +dec_waiting: atomic_dec(&conf->nr_waiting[idx]); spin_unlock_irq(&conf->resync_lock); + return ret; } -static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) +static bool wait_read_barrier(struct r1conf *conf, sector_t sector_nr, + bool nowait) { int idx = sector_to_idx(sector_nr); + bool ret = true; /* * Very similar to _wait_barrier(). The difference is, for read @@ -964,7 +976,7 @@ static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) atomic_inc(&conf->nr_pending[idx]); if (!READ_ONCE(conf->array_frozen)) - return; + return ret; spin_lock_irq(&conf->resync_lock); atomic_inc(&conf->nr_waiting[idx]); @@ -975,19 +987,31 @@ static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) */ wake_up(&conf->wait_barrier); /* Wait for array to be unfrozen */ - wait_event_lock_irq(conf->wait_barrier, - !conf->array_frozen, - conf->resync_lock); + if (conf->array_frozen) { + /* If nowait flag is set, return false to + * show we did not wait + */ + if (nowait) { + ret = false; + goto dec_waiting; + } else { + wait_event_lock_irq(conf->wait_barrier, + !conf->array_frozen, + conf->resync_lock); + } + } atomic_inc(&conf->nr_pending[idx]); +dec_waiting: atomic_dec(&conf->nr_waiting[idx]); spin_unlock_irq(&conf->resync_lock); + return ret; } -static void wait_barrier(struct r1conf *conf, sector_t sector_nr) +static bool wait_barrier(struct r1conf *conf, sector_t sector_nr, bool nowait) { int idx = sector_to_idx(sector_nr); - _wait_barrier(conf, idx); + return _wait_barrier(conf, idx, nowait); } static void wait_all_barriers(struct r1conf *conf) @@ -995,7 +1019,7 @@ static void wait_all_barriers(struct r1conf *conf) int idx; for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) - _wait_barrier(conf, idx); + _wait_barrier(conf, idx, false); } static void _allow_barrier(struct r1conf *conf, int idx) @@ -1212,7 +1236,11 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, * Still need barrier for READ in case that whole * array is frozen. */ - wait_read_barrier(conf, bio->bi_iter.bi_sector); + if (!wait_read_barrier(conf, bio->bi_iter.bi_sector, + bio->bi_opf & REQ_NOWAIT)) { + bio_wouldblock_error(bio); + return; + } if (!r1_bio) r1_bio = alloc_r1bio(mddev, bio); @@ -1321,6 +1349,11 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, * an interruptible wait. */ DEFINE_WAIT(w); + if (bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + return; + } + for (;;) { sigset_t full, old; prepare_to_wait(&conf->wait_barrier, @@ -1339,17 +1372,26 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, } finish_wait(&conf->wait_barrier, &w); } - wait_barrier(conf, bio->bi_iter.bi_sector); - - r1_bio = alloc_r1bio(mddev, bio); - r1_bio->sectors = max_write_sectors; + if (!wait_barrier(conf, bio->bi_iter.bi_sector, + bio->bi_opf & REQ_NOWAIT)) { + bio_wouldblock_error(bio); + return; + } if (conf->pending_count >= max_queued_requests) { md_wakeup_thread(mddev->thread); + if (bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + return; + } raid1_log(mddev, "wait queued"); wait_event(conf->wait_barrier, conf->pending_count < max_queued_requests); } + + r1_bio = alloc_r1bio(mddev, bio); + r1_bio->sectors = max_write_sectors; + /* first select target devices under rcu_lock and * inc refcount on their rdev. Record them by setting * bios[x] to bio @@ -1435,9 +1477,15 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, rdev_dec_pending(conf->mirrors[j].rdev, mddev); r1_bio->state = 0; allow_barrier(conf, bio->bi_iter.bi_sector); + + if (bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + free_r1bio(r1_bio); + return; + } raid1_log(mddev, "wait rdev %d blocked", blocked_rdev->raid_disk); md_wait_for_blocked_rdev(blocked_rdev, mddev); - wait_barrier(conf, bio->bi_iter.bi_sector); + wait_barrier(conf, bio->bi_iter.bi_sector, false); goto retry_write; } -- 2.14.2
