ocfs2: flock: drop cross-node lock when failed locally

ocfs2_do_flock() calls ocfs2_file_lock() to get the cross-node clock and
then call flock_lock_file_wait() to compete with local processes.  In
case flock_lock_file_wait() failed, say -ENOMEM, clean up work is not
done.  This patch adds the cleanup --drop the cross-node lock which was
just granted.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Cc: Joel Becker <jlbec@evilplan.org>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/locks.c

@@ -82,6 +82,8 @@ static int ocfs2_do_flock(struct file *file, struct inode *inode,
 	}
 
 	ret = flock_lock_file_wait(file, fl);
+	if (ret)
+		ocfs2_file_unlock(file);
 
 out:
 	mutex_unlock(&fp->fp_mutex);