svcrpc: autoload rdma module

This should fix failures like:

	# rpc.nfsd --rdma
	rpc.nfsd: Unable to request RDMA services: Protocol not supported

Reported-by: Steve Dickson <steved@redhat.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/svc_xprt.c

@@ -244,13 +244,12 @@ void svc_add_new_perm_xprt(struct svc_serv *serv, struct svc_xprt *new)
 	svc_xprt_received(new);
 }
 
-int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
+int _svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
 		    struct net *net, const int family,
 		    const unsigned short port, int flags)
 {
 	struct svc_xprt_class *xcl;
 
-	dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
 	spin_lock(&svc_xprt_class_lock);
 	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
 		struct svc_xprt *newxprt;
@@ -274,12 +273,28 @@ int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
 	}
  err:
 	spin_unlock(&svc_xprt_class_lock);
-	dprintk("svc: transport %s not found\n", xprt_name);
-
 	/* This errno is exposed to user space.  Provide a reasonable
 	 * perror msg for a bad transport. */
 	return -EPROTONOSUPPORT;
 }
+
+int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
+		    struct net *net, const int family,
+		    const unsigned short port, int flags)
+{
+	int err;
+
+	dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
+	err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
+	if (err == -EPROTONOSUPPORT) {
+		request_module("svc%s", xprt_name);
+		err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
+	}
+	if (err)
+		dprintk("svc: transport %s not found, err %d\n",
+			xprt_name, err);
+	return err;
+}
 EXPORT_SYMBOL_GPL(svc_create_xprt);
 
 /*