NFS/SUNRPC: support transport protocol naming

To prepare for including non-sockets-based RPC transports, select
RPC transports by an identifier (to be used in following patches).

Signed-off-by: Tom Talpey <tmt@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/xprtsock.h b/include/linux/sunrpc/xprtsock.h
index 9bde770..2c6c2c2 100644
--- a/include/linux/sunrpc/xprtsock.h
+++ b/include/linux/sunrpc/xprtsock.h
@@ -19,6 +19,17 @@
 void		cleanup_socket_xprt(void);
 
 /*
+ * RPC transport identifiers for UDP, TCP
+ *
+ * To preserve compatibility with the historical use of raw IP protocol
+ * id's for transport selection, these are specified with the previous
+ * values. No such restriction exists for new transports, except that
+ * they may not collide with these values (17 and 6, respectively).
+ */
+#define XPRT_TRANSPORT_UDP	IPPROTO_UDP
+#define XPRT_TRANSPORT_TCP	IPPROTO_TCP
+
+/*
  * RPC slot table sizes for UDP, TCP transports
  */
 extern unsigned int xprt_udp_slot_table_entries;