[PATCH] md/raid1,raid10: strip REQ_NOWAIT from member bios

[Zheng Qixing]

From: Zheng Qixing <zhengqixing@xxxxxxxxxx>

RAID layers don't implement proper non-blocking semantics for
REQ_NOWAIT, making the flag potentially misleading when propagated
to member disks.

This patch clear REQ_NOWAIT from cloned bios in raid1/raid10. Retain
original bio's REQ_NOWAIT flag for upper layer error handling.

Maybe we can implement non-blocking I/O handling mechanisms within
RAID in future work.

Signed-off-by: Zheng Qixing <zhengqixing@xxxxxxxxxx>
---
 drivers/md/raid1.c  | 3 ++-
 drivers/md/raid10.c | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 19c5a0ce5a40..213ad5b7e20b 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1399,7 +1399,7 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 	}
 	read_bio = bio_alloc_clone(mirror->rdev->bdev, bio, gfp,
 				   &mddev->bio_set);
-
+	read_bio->bi_opf &= ~REQ_NOWAIT;
 	r1_bio->bios[rdisk] = read_bio;
 
 	read_bio->bi_iter.bi_sector = r1_bio->sector +
@@ -1649,6 +1649,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 				wait_for_serialization(rdev, r1_bio);
 		}
 
+		mbio->bi_opf &= ~REQ_NOWAIT;
 		r1_bio->bios[i] = mbio;
 
 		mbio->bi_iter.bi_sector	= (r1_bio->sector + rdev->data_offset);
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index b74780af4c22..951b9b443cd1 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1221,6 +1221,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 		r10_bio->master_bio = bio;
 	}
 	read_bio = bio_alloc_clone(rdev->bdev, bio, gfp, &mddev->bio_set);
+	read_bio->bi_opf &= ~REQ_NOWAIT;
 
 	r10_bio->devs[slot].bio = read_bio;
 	r10_bio->devs[slot].rdev = rdev;
@@ -1256,6 +1257,7 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
 			     conf->mirrors[devnum].rdev;
 
 	mbio = bio_alloc_clone(rdev->bdev, bio, GFP_NOIO, &mddev->bio_set);
+	mbio->bi_opf &= ~REQ_NOWAIT;
 	if (replacement)
 		r10_bio->devs[n_copy].repl_bio = mbio;
 	else
-- 
2.39.2