md/raid1: free r1_bio when REQ_NOWAIT is set and read would block on retry

[ Upstream commit 69ad6ce ]

When a read is retried, raid1_read_request() may be called with a
pre-allocated r1_bio. If wait_read_barrier() fails for a REQ_NOWAIT
read, the bio is completed and the function returns immediately. In this
case the existing r1_bio is leaked.

This fixes a leak of pre-allocated r1_bio structures for retried reads.

Fixes: 5aa7050 ("md: raid1 add nowait support")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260611083514.754922-1-abd.masalkhi@gmail.com?part=1
Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Link: https://patch.msgid.link/20260611101350.759154-1-abd.masalkhi@gmail.com
Signed-off-by: Yu Kuai <yukuai@fygo.io>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: masalkhi

drivers/md/raid1.c

@@ -1244,6 +1244,12 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 	if (!wait_read_barrier(conf, bio->bi_iter.bi_sector,
 				bio->bi_opf & REQ_NOWAIT)) {
 		bio_wouldblock_error(bio);
+
+		if (r1bio_existed) {
+			set_bit(R1BIO_Returned, &r1_bio->state);
+			raid_end_bio_io(r1_bio);
+		}
+
 		return;
 	}