From c74821447915812231409bc1ee815007c1602a24 Mon Sep 17 00:00:00 2001

From: Pavel Machek <pavel@ucw.cz>

Date: Thu, 6 Aug 2020 23:18:09 -0700

Subject: [PATCH 2/6] ocfs2: fix unbalanced locking

Git-commit: 57c720d4144a9c2b88105c3e8f7b0e97e4b5cc93

Patch-mainline: v5.9-rc1

References: git-fixes

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>

Acked-by: Denis Kirjanov <denis.kirjanov@suse.com>

---

 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 586b083e723e..9ccbf868f264 100644

--- a/fs/ocfs2/dlmglue.c

+++ b/fs/ocfs2/dlmglue.c

@@ -2801,9 +2801,15 @@ 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;

 }

-- 

2.16.4