[PATCH] raid1: fix nr_pending leak in REQ_ATOMIC bad-block error path

[Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>]

In raid1_write_request(), each per-mirror loop iteration begins by
incrementing rdev->nr_pending. If a REQ_ATOMIC write encounters a
badblock within the requested range, the code jumps to err_handle
without dropping the reference taken for the current mirror.

err_handle's cleanup loop will only decrements for k < i and
r1_bio->bios[k] is non-NULL. The current slot is therefore skipped,
leaving its nr_pending reference leaked permanently. The reference
prevents the rdev from ever being removed, since raid1_remove_conf()
refuses to remove an rdev with nr_pending > 0.

Fix this by calling rdev_dec_pending() before jumping to err_handle.

Fixes: f2a38abf5f1c ("md/raid1: Atomic write support")
Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
---
 drivers/md/raid1.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 181400e147c0..0084bbc24076 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1580,8 +1580,10 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 				 * complexity of supporting that is not worth
 				 * the benefit.
 				 */
-				if (bio->bi_opf & REQ_ATOMIC)
+				if (bio->bi_opf & REQ_ATOMIC) {
+					rdev_dec_pending(rdev, mddev);
 					goto err_handle;
+				}
 
 				good_sectors = first_bad - r1_bio->sector;
 				if (good_sectors < max_sectors)
-- 
2.43.0