[PATCH 003 of 4] Make RPC 'ping' requests fail more quickly.

[NeilBrown <neilb@suse.de>]

Sometimes when an RPC client is created, an initial 'PING' is sent to
the RPC/NULL procedure to make sure the server is running.
This is always done as a 'soft' call so a major timeout will be fatal.

We change semantics so that if portmap reports that the service does
not exist, or if a ECONNREFUSED error is returned we abort early
rather than persist for the full timeout.

The core mechanism is a new flag RPC_TASK_ACCEPT_NO which tell the rpc
client to accept a 'no' answer rather than retrying.

This patch also causes lockd clients to *not* do the initial 'ping'
otherwise a lock request could fail due to a missing server, even on a
hard mount.

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

### Diffstat output
 ./fs/lockd/host.c              |    1 +
 ./include/linux/sunrpc/sched.h |    4 ++++
 ./net/sunrpc/clnt.c            |   14 +++++++++++---
 ./net/sunrpc/pmap_clnt.c       |    4 +++-
 4 files changed, 19 insertions(+), 4 deletions(-)

diff .prev/fs/lockd/host.c ./fs/lockd/host.c
--- .prev/fs/lockd/host.c	2006-10-24 10:09:41.000000000 +1000
+++ ./fs/lockd/host.c	2006-10-24 11:48:05.000000000 +1000
@@ -236,6 +236,7 @@ nlm_bind_host(struct nlm_host *host)
 			.version	= host->h_version,
 			.authflavor	= RPC_AUTH_UNIX,
 			.flags		= (RPC_CLNT_CREATE_HARDRTRY |
+					   RPC_CLNT_CREATE_NOPING |
 					   RPC_CLNT_CREATE_AUTOBIND),
 		};
 

diff .prev/include/linux/sunrpc/sched.h ./include/linux/sunrpc/sched.h
--- .prev/include/linux/sunrpc/sched.h	2006-10-24 11:35:21.000000000 +1000
+++ ./include/linux/sunrpc/sched.h	2006-10-24 11:46:25.000000000 +1000
@@ -133,6 +133,10 @@ struct rpc_call_ops {
 #define RPC_TASK_KILLED		0x0100		/* task was killed */
 #define RPC_TASK_SOFT		0x0200		/* Use soft timeouts */
 #define RPC_TASK_NOINTR		0x0400		/* uninterruptible task */
+#define RPC_TASK_ACCEPT_NO	0x0800		/* Accept a 'no' such as
+						 * -ECONNREFUSED or '0' from
+						 * portmap, to be reliable.
+						 */
 
 #define RPC_IS_ASYNC(t)		((t)->tk_flags & RPC_TASK_ASYNC)
 #define RPC_IS_SWAPPER(t)	((t)->tk_flags & RPC_TASK_SWAPPER)

diff .prev/net/sunrpc/clnt.c ./net/sunrpc/clnt.c
--- .prev/net/sunrpc/clnt.c	2006-10-24 09:43:48.000000000 +1000
+++ ./net/sunrpc/clnt.c	2006-10-24 11:45:54.000000000 +1000
@@ -221,7 +221,7 @@ struct rpc_clnt *rpc_create(struct rpc_c
 		return clnt;
 
 	if (!(args->flags & RPC_CLNT_CREATE_NOPING)) {
-		int tskflags = RPC_TASK_SOFT;
+		int tskflags = RPC_TASK_SOFT | RPC_TASK_ACCEPT_NO;
 		int err;
 		if ( ! (args->flags & RPC_CLNT_CREATE_INTR))
 			tskflags |= RPC_TASK_NOINTR;
@@ -868,6 +868,8 @@ call_bind_status(struct rpc_task *task)
 	case -EACCES:
 		dprintk("RPC: %4d remote rpcbind: RPC program/version unavailable\n",
 				task->tk_pid);
+		if (task->tk_flags & RPC_TASK_ACCEPT_NO)
+			break;
 		rpc_delay(task, 3*HZ);
 		goto retry_timeout;
 	case -ETIMEDOUT:
@@ -941,6 +943,8 @@ call_connect_status(struct rpc_task *tas
 	switch (status) {
 	case -ENOTCONN:
 	case -EAGAIN:
+		if (task->tk_flags & RPC_TASK_ACCEPT_NO)
+			break;
 		task->tk_action = call_bind;
 		if (!RPC_IS_SOFT(task))
 			return;
@@ -1044,8 +1048,12 @@ call_status(struct rpc_task *task)
 		break;
 	case -ECONNREFUSED:
 	case -ENOTCONN:
-		rpc_force_rebind(clnt);
-		task->tk_action = call_bind;
+		if (task->tk_flags & RPC_TASK_ACCEPT_NO)
+			rpc_exit(task, status);
+		else {
+			rpc_force_rebind(clnt);
+			task->tk_action = call_bind;
+		}
 		break;
 	case -EAGAIN:
 		task->tk_action = call_transmit;

diff .prev/net/sunrpc/pmap_clnt.c ./net/sunrpc/pmap_clnt.c
--- .prev/net/sunrpc/pmap_clnt.c	2006-10-24 09:33:08.000000000 +1000
+++ ./net/sunrpc/pmap_clnt.c	2006-10-24 11:51:32.000000000 +1000
@@ -139,7 +139,9 @@ void rpc_getport(struct rpc_task *task)
 		goto bailout;
 
 	status = -EIO;
-	child = rpc_run_task(pmap_clnt, RPC_TASK_ASYNC, &pmap_getport_ops, map);
+	child = rpc_run_task(pmap_clnt,
+			     RPC_TASK_ASYNC | (task->tk_flags & RPC_TASK_ACCEPT_NO),
+			     &pmap_getport_ops, map);
 	if (IS_ERR(child))
 		goto bailout;
 	rpc_release_task(child);

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