3 files changed, 44 insertions, 23 deletions

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index b3ff9a815e6f..8a0629abb86a 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -232,7 +232,7 @@ int			xprt_unregister_transport(struct xprt_class *type);
 void                    xprt_set_retrans_timeout_def(struct rpc_task *task);
 void                    xprt_set_retrans_timeout_rtt(struct rpc_task *task);
 void                    xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status);
-void                    xprt_wait_for_buffer_space(struct rpc_task *task);
+void                    xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action);
 void                    xprt_write_space(struct rpc_xprt *xprt);
 void                    xprt_update_rtt(struct rpc_task *task);
 void                    xprt_adjust_cwnd(struct rpc_task *task, int result);
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 85199c647022..3ba64f9f84ba 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -447,13 +447,13 @@ EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
  * @task: task to be put to sleep
  *
  */
-void xprt_wait_for_buffer_space(struct rpc_task *task)
+void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 {
         struct rpc_rqst *req = task->tk_rqstp;
         struct rpc_xprt *xprt = req->rq_xprt;
 
         task->tk_timeout = req->rq_timeout;
-        rpc_sleep_on(&xprt->pending, task, NULL);
+        rpc_sleep_on(&xprt->pending, task, action);
 }
 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 8bd3b0f73ac0..4c2462e2f2b2 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -516,6 +516,14 @@ out:
         return sent;
 }
 
+static void xs_nospace_callback(struct rpc_task *task)
+{
+        struct sock_xprt *transport = container_of(task->tk_rqstp->rq_xprt, struct sock_xprt, xprt);
+
+        transport->inet->sk_write_pending--;
+        clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
+}
+
 /**
  * xs_nospace - place task on wait queue if transmit was incomplete
  * @task: task to put to sleep
@@ -531,20 +539,27 @@ static void xs_nospace(struct rpc_task *task)
                         task->tk_pid, req->rq_slen - req->rq_bytes_sent,
                         req->rq_slen);
 
-        if (test_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags)) {
-                /* Protect against races with write_space */
-                spin_lock_bh(&xprt->transport_lock);
-
-                /* Don't race with disconnect */
-                if (!xprt_connected(xprt))
-                        task->tk_status = -ENOTCONN;
-                else if (test_bit(SOCK_NOSPACE, &transport->sock->flags))
-                        xprt_wait_for_buffer_space(task);
+        /* Protect against races with write_space */
+        spin_lock_bh(&xprt->transport_lock);
+
+        /* Don't race with disconnect */
+        if (xprt_connected(xprt)) {
+                if (test_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags)) {
+                        /*
+                         * Notify TCP that we're limited by the application
+                         * window size
+                         */
+                        set_bit(SOCK_NOSPACE, &transport->sock->flags);
+                        transport->inet->sk_write_pending++;
+                        /* ...and wait for more buffer space */
+                        xprt_wait_for_buffer_space(task, xs_nospace_callback);
+                }
+        } else {
+                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
+                task->tk_status = -ENOTCONN;
+        }
 
-                spin_unlock_bh(&xprt->transport_lock);
-        } else
-                /* Keep holding the socket if it is blocked */
-                rpc_delay(task, HZ>>4);
+        spin_unlock_bh(&xprt->transport_lock);
 }
 
 /**
@@ -588,19 +603,20 @@ static int xs_udp_send_request(struct rpc_task *task)
         }
 
         switch (status) {
+        case -EAGAIN:
+                xs_nospace(task);
+                break;
         case -ENETUNREACH:
         case -EPIPE:
         case -ECONNREFUSED:
                 /* When the server has died, an ICMP port unreachable message
                  * prompts ECONNREFUSED. */
-                break;
-        case -EAGAIN:
-                xs_nospace(task);
+                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
                 break;
         default:
+                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
                 dprintk("RPC:       sendmsg returned unrecognized error %d\n",
                         -status);
-                break;
         }
 
         return status;
@@ -695,12 +711,13 @@ static int xs_tcp_send_request(struct rpc_task *task)
         case -ENOTCONN:
         case -EPIPE:
                 status = -ENOTCONN;
+                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
                 break;
         default:
                 dprintk("RPC:       sendmsg returned unrecognized error %d\n",
                         -status);
+                clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
                 xs_tcp_shutdown(xprt);
-                break;
         }
 
         return status;
@@ -1189,9 +1206,11 @@ static void xs_udp_write_space(struct sock *sk)
 
                 if (unlikely(!(sock = sk->sk_socket)))
                         goto out;
+                clear_bit(SOCK_NOSPACE, &sock->flags);
+
                 if (unlikely(!(xprt = xprt_from_sock(sk))))
                         goto out;
-                if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
+                if (test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags) == 0)
                         goto out;
 
                 xprt_write_space(xprt);
@@ -1222,9 +1241,11 @@ static void xs_tcp_write_space(struct sock *sk)
 
                 if (unlikely(!(sock = sk->sk_socket)))
                         goto out;
+                clear_bit(SOCK_NOSPACE, &sock->flags);
+
                 if (unlikely(!(xprt = xprt_from_sock(sk))))
                         goto out;
-                if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
+                if (test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags) == 0)
                         goto out;
 
                 xprt_write_space(xprt);