fs: orangefs: fix error return code of orangefs_revalidate_lookup()

When op_alloc() returns NULL to new_op, no error return code of
orangefs_revalidate_lookup() is assigned.
To fix this bug, ret is assigned with -ENOMEM in this case.

Fixes: 8bb8aefd ("OrangeFS: Change almost all instances of the string PVFS2 to OrangeFS.")
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

fs/orangefs/dcache.c

@@ -26,8 +26,10 @@ static int orangefs_revalidate_lookup(struct dentry *dentry)
 	gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: attempting lookup.\n", __func__);
 
 	new_op = op_alloc(ORANGEFS_VFS_OP_LOOKUP);
-	if (!new_op)
+	if (!new_op) {
+		ret = -ENOMEM;
 		goto out_put_parent;
+	}
 
 	new_op->upcall.req.lookup.sym_follow = ORANGEFS_LOOKUP_LINK_NO_FOLLOW;
 	new_op->upcall.req.lookup.parent_refn = parent->refn;