Re: [PATCH 0/4] 2.6.21-rc7 NFS writes: fix a series of issues

Trond Myklebust
2007-04-19T15:17:32Z

On Thu, 2007-04-19 at 11:12 -0400, Chuck Lever wrote:
> Perhaps instead of looking at the number of bytes sent, the logic in the
> last hunk of this patch should check which queue the request is sitting on.

??? It would be a bug for the request to be sitting on _any_ queue when
it enters xprt_transmit().

Here is the patch that I'm currently testing.

Cheers
Trond
---------------------------
From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Thu, 19 Apr 2007 09:55:44 -0400
RPC: Fix the TCP resend semantics for NFSv4

Fix a regression due to the patch "NFS: disconnect before retrying NFSv4
requests over TCP"

The assumption made in xprt_transmit() that the condition
"req->rq_bytes_sent == 0 and request is on the receive list"
should imply that we're dealing with a retransmission is false.
Firstly, it may simply happen that the socket send queue was full
at the time the request was initially sent through xprt_transmit().
Secondly, doing this for each request that was retransmitted implies
that we disconnect and reconnect for _every_ request that happened to
be retransmitted irrespective of whether or not a disconnection has
already occurred.

Fix is to move this logic into the call_status request timeout handler.

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

net/sunrpc/clnt.c | 4 ++++
net/sunrpc/xprt.c | 10 ----------
2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 6d7221f..396cdbe 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1046,6 +1046,8 @@ call_status(struct rpc_task *task)
rpc_delay(task, 3*HZ);
case -ETIMEDOUT:
task->tk_action = call_timeout;
+ if (task->tk_client->cl_discrtry)
+ xprt_disconnect(task->tk_xprt);
break;
case -ECONNREFUSED:
case -ENOTCONN:
@@ -1169,6 +1171,8 @@ call_decode(struct rpc_task *task)
out_retry:
req->rq_received = req->rq_private_buf.len = 0;
task->tk_status = 0;
+ if (task->tk_client->cl_discrtry)
+ xprt_disconnect(task->tk_xprt);
}

/*
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index ee6ffa0..456a145 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -735,16 +735,6 @@ void xprt_transmit(struct rpc_task *task)
xprt_reset_majortimeo(req);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
- } else {
- /* If all request bytes have been sent,
- * then we must be retransmitting this one */
- if (!req->rq_bytes_sent) {
- if (task->tk_client->cl_discrtry) {
- xprt_disconnect(xprt);
- task->tk_status = -ENOTCONN;
- return;
- }
- }
}
} else if (!req->rq_bytes_sent)
return;