From 1de356b13c9960cfe5dc180cf9774af92b6a9b91 Mon Sep 17 00:00:00 2001
From: Wu Bo <wubo40@huawei.com>
Date: Thu, 30 Apr 2020 14:12:49 +0800
Subject: [PATCH] ceph: fix double unlock in handle_cap_export()

[ Upstream commit 4d8e28ff3106b093d98bfd2eceb9b430c70a8758 ]

If the ceph_mdsc_open_export_target_session() return fails, it will
do a "goto retry", but the session mutex has already been unlocked.
Re-lock the mutex in that case to ensure that we don't unlock it
twice.

Signed-off-by: Wu Bo <wubo40@huawei.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ceph/caps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 617e9ae67f50..e11aacb35d6b 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3394,6 +3394,7 @@ retry:
 		WARN_ON(1);
 		tsession = NULL;
 		target = -1;
+		mutex_lock(&session->s_mutex);
 	}
 	goto retry;