SUNRPC: transport switch API for setting port number

 At some point, transport endpoint addresses will no longer be IPv4.  To hide
 the structure of the rpc_xprt's address field from ULPs and port mappers,
 add an API for setting the port number during an RPC bind operation.

 Test-plan:
 Destructive testing (unplugging the network temporarily).  Connectathon
 with UDP and TCP.  NFSv2/3 and NFSv4 mounting should be carefully checked.
 Probably need to rig a server where certain services aren't running, or
 that returns an error for some typical operation.

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/pmap_clnt.c b/net/sunrpc/pmap_clnt.c
index cad4568..0935adb 100644
--- a/net/sunrpc/pmap_clnt.c
+++ b/net/sunrpc/pmap_clnt.c
@@ -131,10 +131,13 @@
 pmap_getport_done(struct rpc_task *task)
 {
 	struct rpc_clnt	*clnt = task->tk_client;
+	struct rpc_xprt *xprt = task->tk_xprt;
 	struct rpc_portmap *map = clnt->cl_pmap;
 
 	dprintk("RPC: %4d pmap_getport_done(status %d, port %d)\n",
 			task->tk_pid, task->tk_status, clnt->cl_port);
+
+	xprt->ops->set_port(xprt, 0);
 	if (task->tk_status < 0) {
 		/* Make the calling task exit with an error */
 		task->tk_action = rpc_exit_task;
@@ -142,9 +145,8 @@
 		/* Program not registered */
 		rpc_exit(task, -EACCES);
 	} else {
-		/* byte-swap port number first */
+		xprt->ops->set_port(xprt, clnt->cl_port);
 		clnt->cl_port = htons(clnt->cl_port);
-		clnt->cl_xprt->addr.sin_port = clnt->cl_port;
 	}
 	spin_lock(&pmap_lock);
 	map->pm_binding = 0;
@@ -205,7 +207,7 @@
 	xprt = xprt_create_proto(proto, srvaddr, NULL);
 	if (IS_ERR(xprt))
 		return (struct rpc_clnt *)xprt;
-	xprt->addr.sin_port = htons(RPC_PMAP_PORT);
+	xprt->ops->set_port(xprt, RPC_PMAP_PORT);
 	if (!privileged)
 		xprt->resvport = 0;