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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, "Pavel Machek (CIP)" <pavel@denx.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joseph Qi <joseph.qi@linux.alibaba.com>,
        Mark Fasheh <mark@fasheh.com>,
        Joel Becker <jlbec@evilplan.org>,
        Junxiao Bi <junxiao.bi@oracle.com>,
        Changwei Ge <gechangwei@live.cn>, Gang He <ghe@suse.com>,
        Jun Piao <piaojun@huawei.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.7 309/393] ocfs2: fix unbalanced locking
Date:   Mon, 17 Aug 2020 17:15:59 +0200
Message-Id: <20200817143834.600206769@linuxfoundation.org>
In-Reply-To: <20200817143819.579311991@linuxfoundation.org>
References: <20200817143819.579311991@linuxfoundation.org>
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From: Pavel Machek <pavel@ucw.cz>

[ Upstream commit 57c720d4144a9c2b88105c3e8f7b0e97e4b5cc93 ]

Based on what fails, function can return with nfs_sync_rwlock either
locked or unlocked. That can not be right.

Always return with lock unlocked on error.

Fixes: 4cd9973f9ff6 ("ocfs2: avoid inode removal while nfsd is accessing it")
Signed-off-by: Pavel Machek (CIP) <pavel@denx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200724124443.GA28164@duo.ucw.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ocfs2/dlmglue.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 751bc4dc74663..8e3a369086dbd 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2871,9 +2871,15 @@ int ocfs2_nfs_sync_lock(struct ocfs2_super *osb, int ex)
 
 	status = ocfs2_cluster_lock(osb, lockres, ex ? LKM_EXMODE : LKM_PRMODE,
 				    0, 0);
-	if (status < 0)
+	if (status < 0) {
 		mlog(ML_ERROR, "lock on nfs sync lock failed %d\n", status);
 
+		if (ex)
+			up_write(&osb->nfs_sync_rwlock);
+		else
+			up_read(&osb->nfs_sync_rwlock);
+	}
+
 	return status;
 }
 
-- 
2.25.1