[PATCH 3/3] sunrpc: reduce timeout when unregistering rpcbind registrations.

[NeilBrown <neilb@suse.de>]

Unregistering an RPC service is not essential - but it is tidy.
So it is unpleasant to wait a long time for it to complete.

As unregistering is always directed to localhost, the most likely
reason for any delay is the portmap (or rpcbind) is not running.
In that case, waiting it totally pointless.  In any case, we should
expect a quick response, and zero packet loss.

So reduce the timeouts to a total of half a second.

This means that if we try to stop nfsd while portmap is not running,
it takes 3 seconds instead of 3.5 minutes.

Note that stopping portmap before the last nfsd thread has died is
not simply a configuration error.  When we kill nfsd threads they
could take a while to die, and it is possible that portmap could
then be killed before the last nfsd thread has had a change to finish
up.

[An alternate might be to make the sunrpc code always "connect"
udp sockets so that "port not reachable" errors would get reported
back.  This requires a more intrusive change though and might have
other consequences]

Signed-off-by: NeilBrown <neilb@suse.de>
---

 net/sunrpc/rpcb_clnt.c |   17 +++++++++++++++--
 1 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c
index beee6da..31f7e2e 100644
--- a/net/sunrpc/rpcb_clnt.c
+++ b/net/sunrpc/rpcb_clnt.c
@@ -132,7 +132,8 @@ static const struct sockaddr_in rpcb_inaddr_loopback = {
 };
 
 static struct rpc_clnt *rpcb_create_local(struct sockaddr *addr,
-					  size_t addrlen, u32 version)
+					  size_t addrlen, u32 version,
+					  int unregister)
 {
 	struct rpc_create_args args = {
 		.protocol	= XPRT_TRANSPORT_UDP,
@@ -144,6 +145,16 @@ static struct rpc_clnt *rpcb_create_local(struct sockaddr *addr,
 		.authflavor	= RPC_AUTH_UNIX,
 		.flags		= RPC_CLNT_CREATE_NOPING,
 	};
+	const struct rpc_timeout unreg_timeout = {
+		.to_initval = HZ/2,
+		.to_maxval = HZ/2,
+		.to_increment = 0,
+		.to_retries = 0,
+		.to_exponential = 0,
+	};
+
+	if (unregister)
+		args.timeout = &unreg_timeout;
 
 	return rpc_create(&args);
 }
@@ -183,10 +194,12 @@ static int rpcb_register_call(const u32 version, struct rpc_message *msg)
 	size_t addrlen = sizeof(rpcb_inaddr_loopback);
 	struct rpc_clnt *rpcb_clnt;
 	int result, error = 0;
+	int unregister;
 
 	msg->rpc_resp = &result;
 
-	rpcb_clnt = rpcb_create_local(addr, addrlen, version);
+	unregister = (msg->rpc_proc->p_proc == RPCBPROC_UNSET);
+	rpcb_clnt = rpcb_create_local(addr, addrlen, version, unregister);
 	if (!IS_ERR(rpcb_clnt)) {
 		error = rpc_call_sync(rpcb_clnt, msg, 0);
 		rpc_shutdown_client(rpcb_clnt);