[PATCH 5.15 186/279] blk-cgroup: fix missing put device in error path from blkg_conf_pref()

[Greg Kroah-Hartman]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

[ Upstream commit 15c30104965101b8e76b24d27035569d6613a7d6 ]

If blk_queue_enter() failed due to queue is dying, the
blkdev_put_no_open() is needed because blkcg_conf_open_bdev() succeeded.

Fixes: 0c9d338c8443 ("blk-cgroup: synchronize blkg creation against policy deactivation")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211102020705.2321858-1-yukuai3@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 block/blk-cgroup.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index ebff1af402e5b..0eec59e4df65c 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -639,7 +639,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 	 */
 	ret = blk_queue_enter(q, 0);
 	if (ret)
-		return ret;
+		goto fail;
 
 	rcu_read_lock();
 	spin_lock_irq(&q->queue_lock);
@@ -675,13 +675,13 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		new_blkg = blkg_alloc(pos, q, GFP_KERNEL);
 		if (unlikely(!new_blkg)) {
 			ret = -ENOMEM;
-			goto fail;
+			goto fail_exit_queue;
 		}
 
 		if (radix_tree_preload(GFP_KERNEL)) {
 			blkg_free(new_blkg);
 			ret = -ENOMEM;
-			goto fail;
+			goto fail_exit_queue;
 		}
 
 		rcu_read_lock();
@@ -721,9 +721,10 @@ fail_preloaded:
 fail_unlock:
 	spin_unlock_irq(&q->queue_lock);
 	rcu_read_unlock();
+fail_exit_queue:
+	blk_queue_exit(q);
 fail:
 	blkdev_put_no_open(bdev);
-	blk_queue_exit(q);
 	/*
 	 * If queue was bypassing, we should retry.  Do so after a
 	 * short msleep().  It isn't strictly necessary but queue
-- 
2.33.0