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authorVishal Verma <vverma@digitalocean.com>2021-12-21 20:06:20 +0000
committerSong Liu <song@kernel.org>2022-01-06 08:37:02 -0800
commit5aa705039c4fca84575539bfa2b8a28454a3d2ca (patch)
tree21e80f7ed3a99947f3972a371d61accc50128d61
parentf51d46d0e7cb5b8494aa534d276a9d8915a2443d (diff)
md: raid1 add nowait support
This adds nowait support to the RAID1 driver. It makes RAID1 driver return with EAGAIN for situations where it could wait for eg: - Waiting for the barrier, wait_barrier() fn is modified to return bool to support error for wait barriers. It returns true in case of wait or if wait is not required and returns false if wait was required but not performed to support nowait. Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Vishal Verma <vverma@digitalocean.com> Signed-off-by: Song Liu <song@kernel.org>
-rw-r--r--drivers/md/raid1.c76
1 files changed, 56 insertions, 20 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index eeaedd6e0ce1..02db187090fa 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -929,8 +929,10 @@ 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
@@ -961,7 +963,7 @@ 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]
@@ -979,18 +981,27 @@ 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);
- atomic_inc(&conf->nr_pending[idx]);
+
+ /* Return false when nowait flag is set */
+ if (nowait) {
+ ret = false;
+ } 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]);
+ }
+
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
@@ -1002,7 +1013,7 @@ 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]);
@@ -1013,19 +1024,28 @@ 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);
- atomic_inc(&conf->nr_pending[idx]);
+
+ /* Return false when nowait flag is set */
+ if (nowait) {
+ /* Return false when nowait flag is set */
+ ret = false;
+ } else {
+ wait_event_lock_irq(conf->wait_barrier,
+ !conf->array_frozen,
+ conf->resync_lock);
+ atomic_inc(&conf->nr_pending[idx]);
+ }
+
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 _allow_barrier(struct r1conf *conf, int idx)
@@ -1236,7 +1256,11 @@ 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);
@@ -1336,6 +1360,10 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
bio->bi_iter.bi_sector, bio_end_sector(bio))) {
DEFINE_WAIT(w);
+ if (bio->bi_opf & REQ_NOWAIT) {
+ bio_wouldblock_error(bio);
+ return;
+ }
for (;;) {
prepare_to_wait(&conf->wait_barrier,
&w, TASK_IDLE);
@@ -1353,7 +1381,11 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
* thread has put up a bar for new requests.
* Continue immediately if no resync is active currently.
*/
- wait_barrier(conf, bio->bi_iter.bi_sector);
+ if (!wait_barrier(conf, bio->bi_iter.bi_sector,
+ bio->bi_opf & REQ_NOWAIT)) {
+ bio_wouldblock_error(bio);
+ return;
+ }
r1_bio = alloc_r1bio(mddev, bio);
r1_bio->sectors = max_write_sectors;
@@ -1452,9 +1484,14 @@ 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);
+ 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;
}
@@ -1681,7 +1718,7 @@ static void close_sync(struct r1conf *conf)
int idx;
for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) {
- _wait_barrier(conf, idx);
+ _wait_barrier(conf, idx, false);
_allow_barrier(conf, idx);
}
@@ -3403,4 +3440,3 @@ MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
MODULE_ALIAS("md-personality-3"); /* RAID1 */
MODULE_ALIAS("md-raid1");
MODULE_ALIAS("md-level-1");
-