[PATCH] md/raid10: free r10_bio on write NOWAIT exits

[Guangshuo Li]

The change referenced by the Fixes tag made a NOWAIT early exit in
raid10_write_request() free the r10_bio directly instead of using
raid_end_bio_io(), avoiding an unmatched allow_barrier() while still
returning the r10_bio object to the mempool.

The same function has two other NOWAIT early exits. One is before
regular_request_wait(), where the request has not taken a barrier
reference. The other is in the reshape metadata path, where the barrier
reference is released explicitly with allow_barrier(). Both paths end the
bio and return false, but neither returns the r10_bio object to the
mempool.

Free the r10_bio on both NOWAIT exits. Keep the existing barrier handling
unchanged, since only the reshape path has taken a barrier reference.

Fixes: 7d96f3120a7f ("md/raid10: fix deadlock with check operation and nowait requests")
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 drivers/md/raid10.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 0a3cfdd3f5df..d480344c5b8f 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1364,6 +1364,7 @@ static bool raid10_write_request(struct mddev *mddev, struct bio *bio,
 		DEFINE_WAIT(w);
 		/* Bail out if REQ_NOWAIT is set for the bio */
 		if (bio->bi_opf & REQ_NOWAIT) {
+			free_r10bio(r10_bio);
 			bio_wouldblock_error(bio);
 			return false;
 		}
@@ -1397,6 +1398,7 @@ static bool raid10_write_request(struct mddev *mddev, struct bio *bio,
 		md_wakeup_thread(mddev->thread);
 		if (bio->bi_opf & REQ_NOWAIT) {
 			allow_barrier(conf);
+			free_r10bio(r10_bio);
 			bio_wouldblock_error(bio);
 			return false;
 		}
-- 
2.43.0