Re: [PATCH] [Bug 16494] NFS client over TCP hangs due to packet loss

[Andy Chittenden]

On 2010-08-03 10:11, Andrew Morton wrote:
> (cc linux-nfs)
>
> On Tue, 03 Aug 2010 01:21:44 -0700 (PDT) David Miller<davem@xxxxxxxxxxxxx>  wrote:
>
> > From: "Andy Chittenden"<andyc.bluearc@xxxxxxxxx>
> > Date: Tue, 3 Aug 2010 09:14:31 +0100
> >
> > > I don't know whether this patch is the correct fix or not but it enables the
> > > NFS client to recover.
> > >
> > > Kernel version: 2.6.34.1 and 2.6.32.
> > >
> > > Fixes<https://bugzilla.kernel.org/show_bug.cgi?id=16494>. It clears down
> > > any previous shutdown attempts so that reconnects on a socket that's been
> > > shutdown leave the socket in a usable state (otherwise tcp_sendmsg() returns
> > > -EPIPE).
> >
> > If the SunRPC code wants to close a TCP socket then use it again,
> > it should disconnect by doing a connect() with sa_family == AF_UNSPEC

There is code to do that in the SunRPC code in xs_abort_connection() but 
that's conditionally called from xs_tcp_reuse_connection():

static void xs_tcp_reuse_connection(struct rpc_xprt *xprt, struct 
sock_xprt *transport)
{
	unsigned int state = transport->inet->sk_state;

	if (state == TCP_CLOSE && transport->sock->state == SS_UNCONNECTED)
		return;
	if ((1 << state) & (TCPF_ESTABLISHED|TCPF_SYN_SENT))
		return;
	xs_abort_connection(xprt, transport);
}

That's changed since 2.6.26 where it unconditionally did the connect() 
with sa_family == AF_UNSPEC. FWIW we cannot reproduce this problem with 
2.6.26.


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