NFSv4: handle no acl attr

 Stop handing garbage to userspace in the case where a weird server clears the
 acl bit in the getattr return (despite the fact that they've already claimed
 acl support.)
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4xdr.c

@@ -3255,7 +3255,8 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
 		if (attrlen <= *acl_len)
 			xdr_read_pages(xdr, attrlen);
 		*acl_len = attrlen;
-	}
+	} else
+		status = -EOPNOTSUPP;
 
 out:
 	return status;