SUNRPC: Don't retry using the same source port if connection failed

If the TCP connection attempt fails without ever establishing a
connection, then assume the problem may be the server is rejecting us
due to port reuse.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/xprtsock.c

@@ -62,6 +62,7 @@
 #include "sunrpc.h"
 
 static void xs_close(struct rpc_xprt *xprt);
+static void xs_reset_srcport(struct sock_xprt *transport);
 static void xs_set_srcport(struct sock_xprt *transport, struct socket *sock);
 static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
 		struct socket *sock);
@@ -1565,8 +1566,10 @@ static void xs_tcp_state_change(struct sock *sk)
 		break;
 	case TCP_CLOSE:
 		if (test_and_clear_bit(XPRT_SOCK_CONNECTING,
-					&transport->sock_state))
+				       &transport->sock_state)) {
+			xs_reset_srcport(transport);
 			xprt_clear_connecting(xprt);
+		}
 		clear_bit(XPRT_CLOSING, &xprt->state);
 		/* Trigger the socket release */
 		xs_run_error_worker(transport, XPRT_SOCK_WAKE_DISCONNECT);
@@ -1722,6 +1725,11 @@ static void xs_set_port(struct rpc_xprt *xprt, unsigned short port)
 	xs_update_peer_port(xprt);
 }
 
+static void xs_reset_srcport(struct sock_xprt *transport)
+{
+	transport->srcport = 0;
+}
+
 static void xs_set_srcport(struct sock_xprt *transport, struct socket *sock)
 {
 	if (transport->srcport == 0 && transport->xprt.reuseport)