[PATCH 4.9 01/32] Revert "loop: Fix double mutex_unlock(&loop_ctl_mutex) in loop_control_ioctl()"

[Greg Kroah-Hartman]

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

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

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

This reverts commit 5d3cf50105d007adc54949e0caeca1e944549723 which is
commit 628bd85947091830a8c4872adfd5ed1d515a9cf2 upstream.

It does not work properly in the 4.9.y tree and causes more problems
than it fixes, so revert it.

Reported-by: Thomas Lindroth <thomas.lindroth@xxxxxxxxx>
Reported-by: Jan Kara <jack@xxxxxxx>
Cc: syzbot <syzbot+c0138741c2290fc5e63f@xxxxxxxxxxxxxxxxxxxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/block/loop.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1929,10 +1929,12 @@ 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;