From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Set queue flags to QUEUE_FLAG_NOWAIT to indicate REQ_NOWAIT
will be handled.
If an I/O on the md will be delayed, it would bail by calling
bio_wouldblock_error(). The conditions when this could happen are:
+ MD is suspended
+ There is a change pending on the SB, and current I/O would
block until that is complete.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
drivers/md/md.c | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8cdca0296749..d96c27d16841 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -285,6 +285,13 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
bio_endio(bio);
return BLK_QC_T_NONE;
}
+
+ if (mddev->suspended && (bio->bi_opf & REQ_NOWAIT)) {
+ bio_wouldblock_error(bio);
+ rcu_read_unlock();
+ return BLK_QC_T_NONE;
+ }
+
check_suspended:
rcu_read_lock();
if (mddev->suspended) {
@@ -5274,6 +5281,10 @@ static int md_alloc(dev_t dev, char *name)
mddev->queue = NULL;
goto abort;
}
+
+ /* Set the NOWAIT flags to show support */
+ queue_flag_set_unlocked(QUEUE_FLAG_NOWAIT, mddev->queue);
+
disk->major = MAJOR(mddev->unit);
disk->first_minor = unit << shift;
if (name)
@@ -8010,8 +8021,20 @@ bool md_write_start(struct mddev *mddev, struct bio *bi)
rcu_read_unlock();
if (did_change)
sysfs_notify_dirent_safe(mddev->sysfs_state);
- wait_event(mddev->sb_wait,
- !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) && !mddev->suspended);
+
+ /* Don't wait for sb writes if marked with REQ_NOWAIT */
+ if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
+ mddev->suspended) {
+ if (bi->bi_opf & REQ_NOWAIT) {
+ bio_wouldblock_error(bi);
+ percpu_ref_put(&mddev->writes_pending);
+ return false;
+ }
+
+ wait_event(mddev->sb_wait,
+ !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) && !mddev->suspended);
+ }
+
if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
percpu_ref_put(&mddev->writes_pending);
return false;
--
2.12.3
--
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