[patch 021/163] ocfs2: fix unbalanced locking

Andrew Morton
2020-08-07T06:18:13Z

From: Pavel Machek <pavel@ucw.cz>
Subject: ocfs2: fix unbalanced locking

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.

Link: http://lkml.kernel.org/r/20200724124443.GA28164@duo.ucw.cz
Fixes: 4cd9973f9ff6 ("ocfs2: avoid inode removal while nfsd is accessing it")
Signed-off-by: Pavel Machek (CIP) <pavel@denx.de>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

fs/ocfs2/dlmglue.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/ocfs2/dlmglue.c~ocfs2-fix-unbalanced-locking
+++ a/fs/ocfs2/dlmglue.c
@@ -2871,9 +2871,15 @@ int ocfs2_nfs_sync_lock(struct ocfs2_sup

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;
}

_