SUNRPC: Reconnect immediately whenever the server isn't refusing it.

If we've disconnected from the server, rather than the other way round,
then it makes little sense to wait 3 seconds before reconnecting.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/xprtsock.c

@@ -1130,13 +1130,13 @@ static void xs_tcp_state_change(struct sock *sk)
 			transport->tcp_flags =
 				TCP_RCV_COPY_FRAGHDR | TCP_RCV_COPY_XID;
 
-			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
 			xprt_wake_pending_tasks(xprt, 0);
 		}
 		spin_unlock_bh(&xprt->transport_lock);
 		break;
 	case TCP_FIN_WAIT1:
 		/* The client initiated a shutdown of the socket */
+		xprt->reestablish_timeout = 0;
 		set_bit(XPRT_CLOSING, &xprt->state);
 		smp_mb__before_clear_bit();
 		clear_bit(XPRT_CONNECTED, &xprt->state);
@@ -1147,6 +1147,14 @@ static void xs_tcp_state_change(struct sock *sk)
 		/* The server initiated a shutdown of the socket */
 		set_bit(XPRT_CLOSING, &xprt->state);
 		xprt_force_disconnect(xprt);
+	case TCP_SYN_SENT:
+	case TCP_CLOSING:
+		/*
+		 * If the server closed down the connection, make sure that
+		 * we back off before reconnecting
+		 */
+		if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
+			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
 		break;
 	case TCP_LAST_ACK:
 		smp_mb__before_clear_bit();