[PATCH] RPC: allow RPC client's port range to be adjustable

 Select an RPC client source port between 650 and 1023 instead of between
 1 and 800.  The old range conflicts with a number of network services.
 Provide sysctls to allow admins to select a different port range.

 Note that this doesn't affect user-level RPC library behavior, which
 still uses 1 to 800.

 Based on a suggestion by Olaf Kirch <okir@suse.de>.

 Test-plan:
 Repeated mount and unmount.  Destructive testing.  Idle timeouts.

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

include/linux/sunrpc/debug.h

@@ -95,6 +95,8 @@ enum {
 	CTL_NLMDEBUG,
 	CTL_SLOTTABLE_UDP,
 	CTL_SLOTTABLE_TCP,
+	CTL_MIN_RESVPORT,
+	CTL_MAX_RESVPORT,
 };
 
 #endif /* _LINUX_SUNRPC_DEBUG_H_ */

include/linux/sunrpc/xprt.h

@@ -51,6 +51,17 @@ extern unsigned int xprt_tcp_slot_table_entries;
 #define RPC_CALLHDRSIZE		6
 #define RPC_REPHDRSIZE		4
 
+/*
+ * Parameters for choosing a free port
+ */
+extern unsigned int xprt_min_resvport;
+extern unsigned int xprt_max_resvport;
+
+#define RPC_MIN_RESVPORT	(1U)
+#define RPC_MAX_RESVPORT	(65535U)
+#define RPC_DEF_MIN_RESVPORT	(650U)
+#define RPC_DEF_MAX_RESVPORT	(1023U)
+
 /*
  * This describes a timeout strategy
  */
@@ -62,6 +73,9 @@ struct rpc_timeout {
 	unsigned char		to_exponential;
 };
 
+struct rpc_task;
+struct rpc_xprt;
+
 /*
  * This describes a complete RPC request
  */
@@ -107,9 +121,6 @@ struct rpc_rqst {
 #define rq_svec			rq_snd_buf.head
 #define rq_slen			rq_snd_buf.len
 
-struct rpc_task;
-struct rpc_xprt;
-
 struct rpc_xprt_ops {
 	void		(*set_buffer_size)(struct rpc_xprt *xprt);
 	int		(*reserve_xprt)(struct rpc_task *task);

net/sunrpc/sysctl.c

@@ -121,9 +121,16 @@ done:
 
 unsigned int xprt_udp_slot_table_entries = RPC_DEF_SLOT_TABLE;
 unsigned int xprt_tcp_slot_table_entries = RPC_DEF_SLOT_TABLE;
+unsigned int xprt_min_resvport = RPC_DEF_MIN_RESVPORT;
+EXPORT_SYMBOL(xprt_min_resvport);
+unsigned int xprt_max_resvport = RPC_DEF_MAX_RESVPORT;
+EXPORT_SYMBOL(xprt_max_resvport);
+
 
 static unsigned int min_slot_table_size = RPC_MIN_SLOT_TABLE;
 static unsigned int max_slot_table_size = RPC_MAX_SLOT_TABLE;
+static unsigned int xprt_min_resvport_limit = RPC_MIN_RESVPORT;
+static unsigned int xprt_max_resvport_limit = RPC_MAX_RESVPORT;
 
 static ctl_table debug_table[] = {
 	{
@@ -180,6 +187,28 @@ static ctl_table debug_table[] = {
 		.extra1		= &min_slot_table_size,
 		.extra2		= &max_slot_table_size
 	},
+	{
+		.ctl_name	= CTL_MIN_RESVPORT,
+		.procname	= "min_resvport",
+		.data		= &xprt_min_resvport,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.strategy	= &sysctl_intvec,
+		.extra1		= &xprt_min_resvport_limit,
+		.extra2		= &xprt_max_resvport_limit
+	},
+	{
+		.ctl_name	= CTL_MAX_RESVPORT,
+		.procname	= "max_resvport",
+		.data		= &xprt_max_resvport,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.strategy	= &sysctl_intvec,
+		.extra1		= &xprt_min_resvport_limit,
+		.extra2		= &xprt_max_resvport_limit
+	},
 	{ .ctl_name = 0 }
 };
 

net/sunrpc/xprtsock.c

@@ -35,11 +35,6 @@
 #include <net/udp.h>
 #include <net/tcp.h>
 
-/*
- * Maximum port number to use when requesting a reserved port.
- */
-#define XS_MAX_RESVPORT		(800U)
-
 /*
  * How many times to try sending a request on a socket before waiting
  * for the socket buffer to clear.
@@ -873,10 +868,9 @@ static int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
 	struct sockaddr_in myaddr = {
 		.sin_family = AF_INET,
 	};
-	int err, port;
+	int err;
+	unsigned short port = xprt->port;
 
-	/* Were we already bound to a given port? Try to reuse it */
-	port = xprt->port;
 	do {
 		myaddr.sin_port = htons(port);
 		err = sock->ops->bind(sock, (struct sockaddr *) &myaddr,
@@ -887,8 +881,10 @@ static int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
 					port);
 			return 0;
 		}
-		if (--port == 0)
-			port = XS_MAX_RESVPORT;
+		if (port <= xprt_min_resvport)
+			port = xprt_max_resvport;
+		else
+			port--;
 	} while (err == -EADDRINUSE && port != xprt->port);
 
 	dprintk("RPC:      can't bind to reserved port (%d).\n", -err);
@@ -1075,9 +1071,6 @@ static struct rpc_xprt_ops xs_tcp_ops = {
 	.destroy		= xs_destroy,
 };
 
-extern unsigned int xprt_udp_slot_table_entries;
-extern unsigned int xprt_tcp_slot_table_entries;
-
 /**
  * xs_setup_udp - Set up transport to use a UDP socket
  * @xprt: transport to set up
@@ -1098,7 +1091,7 @@ int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 	memset(xprt->slot, 0, slot_table_size);
 
 	xprt->prot = IPPROTO_UDP;
-	xprt->port = XS_MAX_RESVPORT;
+	xprt->port = xprt_max_resvport;
 	xprt->tsh_size = 0;
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	/* XXX: header size can vary due to auth type, IPv6, etc. */
@@ -1136,7 +1129,7 @@ int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 	memset(xprt->slot, 0, slot_table_size);
 
 	xprt->prot = IPPROTO_TCP;
-	xprt->port = XS_MAX_RESVPORT;
+	xprt->port = xprt_max_resvport;
 	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;