svc: Change the svc_sock in the rqstp structure to a transport

The rqstp structure contains a pointer to the transport for the
RPC request. This functionaly trivial patch adds an unamed union
with pointers to both svc_sock and svc_xprt. Ultimately the
union will be removed and only the rq_xprt field will remain. This
allows incrementally extracting transport independent interfaces without
one gigundo patch.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

include/linux/sunrpc/svc.h

@@ -204,7 +204,10 @@ union svc_addr_u {
 struct svc_rqst {
 	struct list_head	rq_list;	/* idle list */
 	struct list_head	rq_all;		/* all threads list */
-	struct svc_sock *	rq_sock;	/* socket */
+	union {
+		struct svc_xprt *	rq_xprt;	/* transport ptr */
+		struct svc_sock *	rq_sock; 	/* socket ptr */
+	};
 	struct sockaddr_storage	rq_addr;	/* peer address */
 	size_t			rq_addrlen;