ocfs2: check if the ocfs2 lock resource has been initialized before c…

…alling ocfs2_dlm_lock

If ocfs2 lockres has not been initialized before calling ocfs2_dlm_lock,
the lock won't be dropped and then will lead umount hung.  The case is
described below:

ocfs2_mknod
    ocfs2_mknod_locked
        __ocfs2_mknod_locked
            ocfs2_journal_access_di
            Failed because of -ENOMEM or other reasons, the inode lockres
            has not been initialized yet.

    iput(inode)
        ocfs2_evict_inode
            ocfs2_delete_inode
                ocfs2_inode_lock
                    ocfs2_inode_lock_full_nested
                        __ocfs2_cluster_lock
                        Succeeds and allocates a new dlm lockres.
            ocfs2_clear_inode
                ocfs2_open_unlock
                    ocfs2_drop_inode_locks
                        ocfs2_drop_lock
                        Since lockres has not been initialized, the lock
                        can't be dropped and the lockres can't be
                        migrated, thus umount will hang forever.

Signed-off-by: Alex Chen <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
Reviewed-by: joyce.xue <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/ocfs2/dlmglue.c

@@ -1391,6 +1391,11 @@ static int __ocfs2_cluster_lock(struct ocfs2_super *osb,
 	int noqueue_attempted = 0;
 	int dlm_locked = 0;
 
+	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED)) {
+		mlog_errno(-EINVAL);
+		return -EINVAL;
+	}
+
 	ocfs2_init_mask_waiter(&mw);
 
 	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)