From: Goldwyn Rodrigues <[email protected]> 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 <[email protected]> --- 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
