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

From: Andy Chittenden
Date: Tue Aug 03 2010 - 06:25:47 EST

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: and 2.6.32.

Fixes<>. 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

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)
if ((1 << state) & (TCPF_ESTABLISHED|TCPF_SYN_SENT))
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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