netdev - RE: [PATCH] [Bug 16494] NFS client over TCP hangs due to packet loss

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Date:	Tue, 10 Aug 2010 09:40:46 +0100
From:	"Andy Chittenden" <andyc.bluearc@...il.com>
To:	"'Trond Myklebust'" <Trond.Myklebust@...app.com>
Cc:	"'Andrew Morton'" <akpm@...ux-foundation.org>,
	"'David Miller'" <davem@...emloft.net>, <kuznet@....inr.ac.ru>,
	<pekkas@...core.fi>, <jmorris@...ei.org>,
	<yoshfuji@...ux-ipv6.org>, <kaber@...sh.net>,
	<eric.dumazet@...il.com>, <William.Allen.Simpson@...il.com>,
	<gilad@...efidence.com>, <ilpo.jarvinen@...sinki.fi>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-nfs@...r.kernel.org>,
	"'J. Bruce Fields'" <bfields@...ldses.org>,
	"'Neil Brown'" <neilb@...e.de>,
	"'Chuck Lever'" <chuck.lever@...cle.com>,
	"'Benny Halevy'" <bhalevy@...asas.com>,
	"'Alexandros Batsakis'" <batsakis@...app.com>,
	"'Joe Perches'" <joe@...ches.com>,
	"Andy Chittenden" <andyc@...earc.com>
Subject: RE: [PATCH] [Bug 16494] NFS client over TCP hangs due to packet loss

> On Mon, 2010-08-09 at 10:27 +0100, Andy Chittenden wrote:
> > A weekend run with that patch applied to 2.6.34.2 was successful. As
> nobody has objected, what's the next step to getting it applied to the
> official source trees?
> 
> Please resend me a version with a cleaned up changelog entry. I can
> then
> push it as a bugfix.
> 
> Cheers
>   Trond

Thanks. I think this sums it up:

SUNRPC: fix NFS client over TCP hangs due to packet loss (Bug 16494)

When reusing a TCP connection, ensure that it's aborted if a previous shutdown attempt has been made on that connection so that the RPC over TCP recovery mechanism succeeds.

# diff -up /home/company/software/src/linux-2.6.34.2/net/sunrpc/xprtsock.c net/sunrpc/xprtsock.c 
--- /home/company/software/src/linux-2.6.34.2/net/sunrpc/xprtsock.c     2010-08-02 18:30:51.000000000 +0100
+++ net/sunrpc/xprtsock.c       2010-08-06 08:09:08.000000000 +0100
@@ -1322,10 +1322,11 @@ static void xs_tcp_state_change(struct s
        if (!(xprt = xprt_from_sock(sk)))
                goto out;
        dprintk("RPC:       xs_tcp_state_change client %p...\n", xprt);
-       dprintk("RPC:       state %x conn %d dead %d zapped %d\n",
+       dprintk("RPC:       state %x conn %d dead %d zapped %d sk_shutdown %d\n",
                        sk->sk_state, xprt_connected(xprt),
                        sock_flag(sk, SOCK_DEAD),
-                       sock_flag(sk, SOCK_ZAPPED));
+                       sock_flag(sk, SOCK_ZAPPED),
+                       sk->sk_shutdown);
 
        switch (sk->sk_state) {
        case TCP_ESTABLISHED:
@@ -1796,10 +1797,25 @@ static void xs_tcp_reuse_connection(stru
 {
        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;
+       if (state == TCP_CLOSE && transport->sock->state == SS_UNCONNECTED) {
+               /* we don't need to abort the connection if the socket
+                * hasn't undergone a shutdown
+                */
+               if (transport->inet->sk_shutdown == 0)
+                       return;
+               dprintk("RPC:       %s: TCP_CLOSEd and sk_shutdown set to %d\n",
+                       __func__, transport->inet->sk_shutdown);
+       }
+       if ((1 << state) & (TCPF_ESTABLISHED|TCPF_SYN_SENT)) {
+               /* we don't need to abort the connection if the socket
+                * hasn't undergone a shutdown
+                */
+               if (transport->inet->sk_shutdown == 0)
+                       return;
+               dprintk("RPC:       %s: ESTABLISHED/SYN_SENT "
+                               "sk_shutdown set to %d\n",
+                               __func__, transport->inet->sk_shutdown);
+       }
        xs_abort_connection(xprt, transport);
 }

Signed-off-by: Andy Chittenden <andyc.bluearc@...il.com>

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