diff options
| author | Vishal Verma <vverma@digitalocean.com> | 2021-12-21 20:06:19 +0000 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2022-01-06 08:37:02 -0800 |
| commit | f51d46d0e7cb5b8494aa534d276a9d8915a2443d (patch) | |
| tree | 1fee981ced8826ed051f0f901cdb137b9af44ecb | |
| parent | a92ce0feffeed8b91f02dac85246d1205e4a64b6 (diff) | |
md: add support for REQ_NOWAIT
commit 021a24460dc2 ("block: add QUEUE_FLAG_NOWAIT") added support
for checking whether a given bdev supports handling of REQ_NOWAIT or not.
Since then commit 6abc49468eea ("dm: add support for REQ_NOWAIT and enable
it for linear target") added support for REQ_NOWAIT for dm. This uses
a similar approach to incorporate REQ_NOWAIT for md based bios.
This patch was tested using t/io_uring tool within FIO. A nvme drive
was partitioned into 2 partitions and a simple raid 0 configuration
/dev/md0 was created.
md0 : active raid0 nvme4n1p1[1] nvme4n1p2[0]
937423872 blocks super 1.2 512k chunks
Before patch:
$ ./t/io_uring /dev/md0 -p 0 -a 0 -d 1 -r 100
Running top while the above runs:
$ ps -eL | grep $(pidof io_uring)
38396 38396 pts/2 00:00:00 io_uring
38396 38397 pts/2 00:00:15 io_uring
38396 38398 pts/2 00:00:13 iou-wrk-38397
We can see iou-wrk-38397 io worker thread created which gets created
when io_uring sees that the underlying device (/dev/md0 in this case)
doesn't support nowait.
After patch:
$ ./t/io_uring /dev/md0 -p 0 -a 0 -d 1 -r 100
Running top while the above runs:
$ ps -eL | grep $(pidof io_uring)
38341 38341 pts/2 00:10:22 io_uring
38341 38342 pts/2 00:10:37 io_uring
After running this patch, we don't see any io worker thread
being created which indicated that io_uring saw that the
underlying device does support nowait. This is the exact behaviour
noticed on a dm device which also supports nowait.
For all the other raid personalities except raid0, we would need
to train pieces which involves make_request fn in order for them
to correctly handle REQ_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/md.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 7fbf6f0ac01b..c6de7d4bfe4d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -418,6 +418,12 @@ check_suspended: rcu_read_lock(); if (is_suspended(mddev, bio)) { DEFINE_WAIT(__wait); + /* Bail out if REQ_NOWAIT is set for the bio */ + if (bio->bi_opf & REQ_NOWAIT) { + rcu_read_unlock(); + bio_wouldblock_error(bio); + return; + } for (;;) { prepare_to_wait(&mddev->sb_wait, &__wait, TASK_UNINTERRUPTIBLE); @@ -5787,6 +5793,7 @@ int md_run(struct mddev *mddev) int err; struct md_rdev *rdev; struct md_personality *pers; + bool nowait = true; if (list_empty(&mddev->disks)) /* cannot run an array with no devices.. */ @@ -5857,8 +5864,13 @@ int md_run(struct mddev *mddev) } } sysfs_notify_dirent_safe(rdev->sysfs_state); + nowait = nowait && blk_queue_nowait(bdev_get_queue(rdev->bdev)); } + /* Set the NOWAIT flags if all underlying devices support it */ + if (nowait) + blk_queue_flag_set(QUEUE_FLAG_NOWAIT, mddev->queue); + if (!bioset_initialized(&mddev->bio_set)) { err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); if (err) @@ -7003,6 +7015,15 @@ static int hot_add_disk(struct mddev *mddev, dev_t dev) if (!mddev->thread) md_update_sb(mddev, 1); /* + * If the new disk does not support REQ_NOWAIT, + * disable on the whole MD. + */ + if (!blk_queue_nowait(bdev_get_queue(rdev->bdev))) { + pr_info("%s: Disabling nowait because %s does not support nowait\n", + mdname(mddev), bdevname(rdev->bdev, b)); + blk_queue_flag_clear(QUEUE_FLAG_NOWAIT, mddev->queue); + } + /* * Kick recovery, maybe this spare has to be added to the * array immediately. */ |