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

["Andy Chittenden" <andyc.bluearc@gmail.com>]

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).

# diff -up /home/company/software/src/linux-2.6.34.1/net/ipv4/tcp_output.c
net/ipv4
--- /home/company/software/src/linux-2.6.34.1/net/ipv4/tcp_output.c
2010-07-27 08:46:46.917000000 +0100
+++ net/ipv4/tcp_output.c       2010-07-27 09:19:16.000000000 +0100
@@ -2522,6 +2522,13 @@ static void tcp_connect_init(struct sock
        struct tcp_sock *tp = tcp_sk(sk);
        __u8 rcv_wscale;

+       /* clear 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).
+        */
+       sk->sk_shutdown = 0;
+
        /* We'll fix this up when we get a response from the other end.
         * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
         */

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