SUNRPC: Clean up the RPCSEC_GSS service ticket requests

Instead of hacking specific service names into gss_encode_v1_msg, we should
just allow the caller to specify the service name explicitly.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/net/sunrpc/auth_generic.c b/net/sunrpc/auth_generic.c
index e010a01..1426ec3 100644
--- a/net/sunrpc/auth_generic.c
+++ b/net/sunrpc/auth_generic.c
@@ -41,15 +41,17 @@
 /*
  * Public call interface for looking up machine creds.
  */
-struct rpc_cred *rpc_lookup_machine_cred(void)
+struct rpc_cred *rpc_lookup_machine_cred(const char *service_name)
 {
 	struct auth_cred acred = {
 		.uid = RPC_MACHINE_CRED_USERID,
 		.gid = RPC_MACHINE_CRED_GROUPID,
+		.principal = service_name,
 		.machine_cred = 1,
 	};
 
-	dprintk("RPC:       looking up machine cred\n");
+	dprintk("RPC:       looking up machine cred for service %s\n",
+			service_name);
 	return generic_auth.au_ops->lookup_cred(&generic_auth, &acred, 0);
 }
 EXPORT_SYMBOL_GPL(rpc_lookup_machine_cred);