[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>

2 files changed, 37 insertions, 15 deletions

diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index ef483262f17f..d0c9f460e411 100644
--- a/net/sunrpc/sysctl.c
+++ b/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 }
 };
 
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 26402c063f00..62c2e7caa345 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -36,11 +36,6 @@
 #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;