NFS RPC_AUTH_GSS unsupported on v4.1 back channel

Signed-off-by: NAndy Adamson <andros@netapp.com>
Acked-by: NBruce Fields <bfields@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/callback.c

@@ -365,6 +365,9 @@ static int check_gss_callback_principal(struct nfs_client *clp,
 	struct rpc_clnt *r = clp->cl_rpcclient;
 	char *p = svc_gss_principal(rqstp);
 
+	/* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
+	if (clp->cl_minorversion != 0)
+		return SVC_DROP;
 	/*
 	 * It might just be a normal user principal, in which case
 	 * userspace won't bother to tell us the name at all.