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.
Signed-off-by: Vishal Verma <vverma@xxxxxxxxxxxxxxxx>
---
drivers/md/md.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 5111ed966947..51b2df32aed5 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -419,6 +419,12 @@ void md_handle_request(struct mddev *mddev, struct bio *bio)
if (is_suspended(mddev, bio)) {
DEFINE_WAIT(__wait);
for (;;) {
+ /* Bail out if REQ_NOWAIT is set for the bio */
+ if (bio->bi_opf & REQ_NOWAIT) {
+ bio_wouldblock_error(bio);
+ break;
+ }
+
prepare_to_wait(&mddev->sb_wait, &__wait,
TASK_UNINTERRUPTIBLE);
if (!is_suspended(mddev, bio))
@@ -5792,6 +5798,7 @@ 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.. */
@@ -5862,8 +5869,14 @@ int md_run(struct mddev *mddev)
}
}
sysfs_notify_dirent_safe(rdev->sysfs_state);
+ if (!blk_queue_nowait(bdev_get_queue(rdev->bdev)))
+ nowait = false;
}
+ /* 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)
@@ -7007,6 +7020,14 @@ static int hot_add_disk(struct mddev *mddev, dev_t dev)
set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
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.
--
2.17.1
