SUNRPC: Respond promptly to server TCP resets

If the server sends us an RST error while we're in the TCP_ESTABLISHED
state, then that will not result in a state change, and so the RPC client
ends up hanging forever (see
http://bugzilla.kernel.org/show_bug.cgi?id=11154)

We can intercept the reset by setting up an sk->sk_error_report callback,
which will then allow us to initiate a proper shutdown and retry...

We also make sure that if the send request receives an ECONNRESET, then we
shutdown too...

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

1 files changed, 48 insertions, 10 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 9a288d5eea64..0a50361e3d83 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -249,6 +249,7 @@ struct sock_xprt {
         void                    (*old_data_ready)(struct sock *, int);
         void                    (*old_state_change)(struct sock *);
         void                    (*old_write_space)(struct sock *);
+        void                    (*old_error_report)(struct sock *);
 };
 
 /*
@@ -698,8 +699,9 @@ static int xs_tcp_send_request(struct rpc_task *task)
         case -EAGAIN:
                 xs_nospace(task);
                 break;
-        case -ECONNREFUSED:
         case -ECONNRESET:
+                xs_tcp_shutdown(xprt);
+        case -ECONNREFUSED:
         case -ENOTCONN:
         case -EPIPE:
                 status = -ENOTCONN;
@@ -742,6 +744,22 @@ out_release:
         xprt_release_xprt(xprt, task);
 }
 
+static void xs_save_old_callbacks(struct sock_xprt *transport, struct sock *sk)
+{
+        transport->old_data_ready = sk->sk_data_ready;
+        transport->old_state_change = sk->sk_state_change;
+        transport->old_write_space = sk->sk_write_space;
+        transport->old_error_report = sk->sk_error_report;
+}
+
+static void xs_restore_old_callbacks(struct sock_xprt *transport, struct sock *sk)
+{
+        sk->sk_data_ready = transport->old_data_ready;
+        sk->sk_state_change = transport->old_state_change;
+        sk->sk_write_space = transport->old_write_space;
+        sk->sk_error_report = transport->old_error_report;
+}
+
 /**
  * xs_close - close a socket
  * @xprt: transport
@@ -765,9 +783,8 @@ static void xs_close(struct rpc_xprt *xprt)
         transport->sock = NULL;
 
         sk->sk_user_data = NULL;
-        sk->sk_data_ready = transport->old_data_ready;
-        sk->sk_state_change = transport->old_state_change;
-        sk->sk_write_space = transport->old_write_space;
+
+        xs_restore_old_callbacks(transport, sk);
         write_unlock_bh(&sk->sk_callback_lock);
 
         sk->sk_no_check = 0;
@@ -1180,6 +1197,28 @@ static void xs_tcp_state_change(struct sock *sk)
 }
 
 /**
+ * xs_tcp_error_report - callback mainly for catching RST events
+ * @sk: socket
+ */
+static void xs_tcp_error_report(struct sock *sk)
+{
+        struct rpc_xprt *xprt;
+
+        read_lock(&sk->sk_callback_lock);
+        if (sk->sk_err != ECONNRESET || sk->sk_state != TCP_ESTABLISHED)
+                goto out;
+        if (!(xprt = xprt_from_sock(sk)))
+                goto out;
+        dprintk("RPC:       %s client %p...\n"
+                        "RPC:       error %d\n",
+                        __func__, xprt, sk->sk_err);
+
+        xprt_force_disconnect(xprt);
+out:
+        read_unlock(&sk->sk_callback_lock);
+}
+
+/**
  * xs_udp_write_space - callback invoked when socket buffer space
  *                             becomes available
  * @sk: socket whose state has changed
@@ -1454,10 +1493,9 @@ static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 
                 write_lock_bh(&sk->sk_callback_lock);
 
+                xs_save_old_callbacks(transport, sk);
+
                 sk->sk_user_data = xprt;
-                transport->old_data_ready = sk->sk_data_ready;
-                transport->old_state_change = sk->sk_state_change;
-                transport->old_write_space = sk->sk_write_space;
                 sk->sk_data_ready = xs_udp_data_ready;
                 sk->sk_write_space = xs_udp_write_space;
                 sk->sk_no_check = UDP_CSUM_NORCV;
@@ -1589,13 +1627,13 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 
                 write_lock_bh(&sk->sk_callback_lock);
 
+                xs_save_old_callbacks(transport, sk);
+
                 sk->sk_user_data = xprt;
-                transport->old_data_ready = sk->sk_data_ready;
-                transport->old_state_change = sk->sk_state_change;
-                transport->old_write_space = sk->sk_write_space;
                 sk->sk_data_ready = xs_tcp_data_ready;
                 sk->sk_state_change = xs_tcp_state_change;
                 sk->sk_write_space = xs_tcp_write_space;
+                sk->sk_error_report = xs_tcp_error_report;
                 sk->sk_allocation = GFP_ATOMIC;
 
                 /* socket options */