SUNRPC: Add a sysctl to control the duration of the socket linger timeout

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/xprtsock.c

@@ -50,6 +50,7 @@ unsigned int xprt_min_resvport = RPC_DEF_MIN_RESVPORT;
 unsigned int xprt_max_resvport = RPC_DEF_MAX_RESVPORT;
 
 #define XS_TCP_LINGER_TO	(15U * HZ)
+static unsigned int xs_tcp_fin_timeout __read_mostly = XS_TCP_LINGER_TO;
 
 /*
  * We can register our own files under /proc/sys/sunrpc by
@@ -118,6 +119,14 @@ static ctl_table xs_tunables_table[] = {
 		.extra1		= &xprt_min_resvport_limit,
 		.extra2		= &xprt_max_resvport_limit
 	},
+	{
+		.procname	= "tcp_fin_timeout",
+		.data		= &xs_tcp_fin_timeout,
+		.maxlen		= sizeof(xs_tcp_fin_timeout),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_jiffies,
+		.strategy	= sysctl_jiffies
+	},
 	{
 		.ctl_name = 0,
 	},
@@ -1222,7 +1231,7 @@ static void xs_tcp_state_change(struct sock *sk)
 		clear_bit(XPRT_CONNECTED, &xprt->state);
 		clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 		smp_mb__after_clear_bit();
-		xs_tcp_schedule_linger_timeout(xprt, XS_TCP_LINGER_TO);
+		xs_tcp_schedule_linger_timeout(xprt, xs_tcp_fin_timeout);
 		break;
 	case TCP_CLOSE_WAIT:
 		/* The server initiated a shutdown of the socket */
@@ -1239,7 +1248,7 @@ static void xs_tcp_state_change(struct sock *sk)
 		break;
 	case TCP_LAST_ACK:
 		set_bit(XPRT_CLOSING, &xprt->state);
-		xs_tcp_schedule_linger_timeout(xprt, XS_TCP_LINGER_TO);
+		xs_tcp_schedule_linger_timeout(xprt, xs_tcp_fin_timeout);
 		smp_mb__before_clear_bit();
 		clear_bit(XPRT_CONNECTED, &xprt->state);
 		smp_mb__after_clear_bit();