linux-kernel - [PATCH AUTOSEL 4.4 09/14] ceph: fix double unlock in handle_cap

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Message-Id: <20200514185625.21753-9-sashal@kernel.org>
Date:   Thu, 14 May 2020 14:56:20 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Wu Bo <wubo40@...wei.com>, "Yan, Zheng" <zyan@...hat.com>,
        Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>, ceph-devel@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 09/14] ceph: fix double unlock in handle_cap_export()

From: Wu Bo <wubo40@...wei.com>

[ 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@...wei.com>
Reviewed-by: "Yan, Zheng" <zyan@...hat.com>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/caps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index efdf81ea3b5f8..3d0497421e62b 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3293,6 +3293,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 		WARN_ON(1);
 		tsession = NULL;
 		target = -1;
+		mutex_lock(&session->s_mutex);
 	}
 	goto retry;
 
-- 
2.20.1