SUNRPC: Allow changing of the TCP timeout parameters on the fly

When the NFSv4 server tells us the lease period, we usually want
to adjust down the timeout parameters on the TCP connection to
ensure that we don't miss lease renewals due to a faulty connection.

Signed-off-by: Trond Myklebust <[e-mail]>
Signed-off-by: Anna Schumaker <[e-mail]>

include/linux/sunrpc/xprt.h

···
 	void		(*release_request)(struct rpc_task *task);
 	void		(*close)(struct rpc_xprt *xprt);
 	void		(*destroy)(struct rpc_xprt *xprt);
+	void		(*set_connect_timeout)(struct rpc_xprt *xprt,
+					unsigned long connect_timeout,
+					unsigned long reconnect_timeout);
 	void		(*print_stats)(struct rpc_xprt *xprt, struct seq_file *seq);
 	int		(*enable_swap)(struct rpc_xprt *xprt);
 	void		(*disable_swap)(struct rpc_xprt *xprt);
···
 	struct timer_list	timer;
 	unsigned long		last_used,
 				idle_timeout,
+				connect_timeout,
 				max_reconnect_timeout;
 
 	/*

include/linux/sunrpc/xprtsock.h

···
 	size_t			rcvsize,
 				sndsize;
 
+	struct rpc_timeout	tcp_timeout;
+
 	/*
 	 * Saved socket callback addresses
 	 */
···
 
 #define XPRT_SOCK_CONNECTING	1U
 #define XPRT_SOCK_DATA_READY	(2)
+#define XPRT_SOCK_UPD_TIMEOUT	(3)
 
 #endif /* __KERNEL__ */
 

net/sunrpc/clnt.c

···
 {
 	struct rpc_xprt_switch *xps;
 	struct rpc_xprt *xprt;
+	unsigned long connect_timeout;
 	unsigned long reconnect_timeout;
 	unsigned char resvport;
 	int ret = 0;
···
 		return -EAGAIN;
 	}
 	resvport = xprt->resvport;
+	connect_timeout = xprt->connect_timeout;
 	reconnect_timeout = xprt->max_reconnect_timeout;
 	rcu_read_unlock();
 
···
 		goto out_put_switch;
 	}
 	xprt->resvport = resvport;
-	xprt->max_reconnect_timeout = reconnect_timeout;
+	if (xprt->ops->set_connect_timeout != NULL)
+		xprt->ops->set_connect_timeout(xprt,
+				connect_timeout,
+				reconnect_timeout);
 
 	rpc_xprt_switch_set_roundrobin(xps);
 	if (setup) {
···
 }
 EXPORT_SYMBOL_GPL(rpc_clnt_add_xprt);
 
+struct connect_timeout_data {
+	unsigned long connect_timeout;
+	unsigned long reconnect_timeout;
+};
+
 static int
-rpc_xprt_cap_max_reconnect_timeout(struct rpc_clnt *clnt,
+rpc_xprt_set_connect_timeout(struct rpc_clnt *clnt,
 		struct rpc_xprt *xprt,
 		void *data)
 {
-	unsigned long timeout = *((unsigned long *)data);
+	struct connect_timeout_data *timeo = data;
 
-	if (timeout < xprt->max_reconnect_timeout)
-		xprt->max_reconnect_timeout = timeout;
+	if (xprt->ops->set_connect_timeout)
+		xprt->ops->set_connect_timeout(xprt,
+				timeo->connect_timeout,
+				timeo->reconnect_timeout);
 	return 0;
 }
 
 void
 rpc_cap_max_reconnect_timeout(struct rpc_clnt *clnt, unsigned long timeo)
 {
+	struct connect_timeout_data timeout = {
+		.connect_timeout = timeo,
+		.reconnect_timeout = timeo,
+	};
 	rpc_clnt_iterate_for_each_xprt(clnt,
-			rpc_xprt_cap_max_reconnect_timeout,
-			&timeo);
+			rpc_xprt_set_connect_timeout,
+			&timeout);
 }
 EXPORT_SYMBOL_GPL(rpc_cap_max_reconnect_timeout);
 

net/sunrpc/xprtsock.c

···
 #include "sunrpc.h"
 
 static void xs_close(struct rpc_xprt *xprt);
+static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
+		struct socket *sock);
 
 /*
  * xprtsock tunables
···
 	 */
 	if (task->tk_flags & RPC_TASK_SENT)
 		zerocopy = false;
+
+	if (test_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state))
+		xs_tcp_set_socket_timeouts(xprt, transport->sock);
 
 	/* Continue transmitting the packet/record. We must be careful
 	 * to cope with writespace callbacks arriving _after_ we have
···
 static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
 		struct socket *sock)
 {
-	unsigned int keepidle = DIV_ROUND_UP(xprt->timeout->to_initval, HZ);
-	unsigned int keepcnt = xprt->timeout->to_retries + 1;
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+	unsigned int keepidle;
+	unsigned int keepcnt;
 	unsigned int opt_on = 1;
 	unsigned int timeo;
+
+	spin_lock_bh(&xprt->transport_lock);
+	keepidle = DIV_ROUND_UP(xprt->timeout->to_initval, HZ);
+	keepcnt = xprt->timeout->to_retries + 1;
+	timeo = jiffies_to_msecs(xprt->timeout->to_initval) *
+		(xprt->timeout->to_retries + 1);
+	clear_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state);
+	spin_unlock_bh(&xprt->transport_lock);
 
 	/* TCP Keepalive options */
 	kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
···
 			(char *)&keepcnt, sizeof(keepcnt));
 
 	/* TCP user timeout (see RFC5482) */
-	timeo = jiffies_to_msecs(xprt->timeout->to_initval) *
-		(xprt->timeout->to_retries + 1);
 	kernel_setsockopt(sock, SOL_TCP, TCP_USER_TIMEOUT,
 			(char *)&timeo, sizeof(timeo));
+}
+
+static void xs_tcp_set_connect_timeout(struct rpc_xprt *xprt,
+		unsigned long connect_timeout,
+		unsigned long reconnect_timeout)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+	struct rpc_timeout to;
+	unsigned long initval;
+
+	spin_lock_bh(&xprt->transport_lock);
+	if (reconnect_timeout < xprt->max_reconnect_timeout)
+		xprt->max_reconnect_timeout = reconnect_timeout;
+	if (connect_timeout < xprt->connect_timeout) {
+		memcpy(&to, xprt->timeout, sizeof(to));
+		initval = DIV_ROUND_UP(connect_timeout, to.to_retries + 1);
+		/* Arbitrary lower limit */
+		if (initval <  XS_TCP_INIT_REEST_TO << 1)
+			initval = XS_TCP_INIT_REEST_TO << 1;
+		to.to_initval = initval;
+		to.to_maxval = initval;
+		memcpy(&transport->tcp_timeout, &to,
+				sizeof(transport->tcp_timeout));
+		xprt->timeout = &transport->tcp_timeout;
+		xprt->connect_timeout = connect_timeout;
+	}
+	set_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state);
+	spin_unlock_bh(&xprt->transport_lock);
 }
 
 static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
···
 	.set_retrans_timeout	= xprt_set_retrans_timeout_def,
 	.close			= xs_tcp_shutdown,
 	.destroy		= xs_destroy,
+	.set_connect_timeout	= xs_tcp_set_connect_timeout,
 	.print_stats		= xs_tcp_print_stats,
 	.enable_swap		= xs_enable_swap,
 	.disable_swap		= xs_disable_swap,
···
 	xprt->timeout = &xs_tcp_default_timeout;
 
 	xprt->max_reconnect_timeout = xprt->timeout->to_maxval;
+	xprt->connect_timeout = xprt->timeout->to_initval *
+		(xprt->timeout->to_retries + 1);
 
 	INIT_WORK(&transport->recv_worker, xs_tcp_data_receive_workfn);
 	INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_setup_socket);