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 <redacted>
---
  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 88b1fce90520..663aabfeba18 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c

@@ -640,7 +640,7 @@ 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);

@@ -676,13 +676,13 @@ 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();

@@ -722,9 +722,10 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
  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