[PATCH 4.20 109/111] loop: Fix double mutex_unlock(&loop_ctl_mutex) in loop_control_ioctl()

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>

commit 628bd85947091830a8c4872adfd5ed1d515a9cf2 upstream.

Commit 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex") forgot to
remove mutex_unlock(&loop_ctl_mutex) from loop_control_ioctl() when
replacing loop_index_mutex with loop_ctl_mutex.

Fixes: 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex")
Reported-by: syzbot <syzbot+c0138741c2290fc5e...@syzkaller.appspotmail.com>
Reviewed-by: Ming Lei <ming....@redhat.com>
Reviewed-by: Jan Kara <j...@suse.cz>
Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/block/loop.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2074,12 +2074,10 @@ static long loop_control_ioctl(struct fi
                        break;
                if (lo->lo_state != Lo_unbound) {
                        ret = -EBUSY;
-                       mutex_unlock(&loop_ctl_mutex);
                        break;
                }
                if (atomic_read(&lo->lo_refcnt) > 0) {
                        ret = -EBUSY;
-                       mutex_unlock(&loop_ctl_mutex);
                        break;
                }
                lo->lo_disk->private_data = NULL;