[PATCH V3 1/2] md: bypass block throttle for superblock update

[Junxiao Bi <junxiao.bi@oracle.com>]

commit 5e2cf333b7bd ("md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d")
introduced a hung bug and will be reverted in next patch, since the issue
that commit is fixing is due to md superblock write is throttled by wbt,
to fix it, we can have superblock write bypass block layer throttle.

Fixes: 5e2cf333b7bd ("md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d")
Suggested-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
---
 v3 <- v2:
 - update patch log

 drivers/md/md.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4ee4593c874a..7a5a22097365 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1013,9 +1013,10 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 		return;
 
 	bio = bio_alloc_bioset(rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev,
-			       1,
-			       REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH | REQ_FUA,
-			       GFP_NOIO, &mddev->sync_set);
+			      1,
+			      REQ_OP_WRITE | REQ_SYNC | REQ_IDLE | REQ_META
+				  | REQ_PREFLUSH | REQ_FUA,
+			      GFP_NOIO, &mddev->sync_set);
 
 	atomic_inc(&rdev->nr_pending);
 
-- 
2.39.3 (Apple Git-145)