3 files changed, 68 insertions, 14 deletions

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index eee1c6877851..86833b725bb5 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -133,6 +133,7 @@ struct rpc_xprt;
 struct rpc_xprt_ops {
         void            (*set_buffer_size)(struct rpc_xprt *xprt);
         int             (*reserve_xprt)(struct rpc_task *task);
+        void            (*release_xprt)(struct rpc_xprt *xprt, struct rpc_task *task);
         void            (*connect)(struct rpc_task *task);
         int             (*send_request)(struct rpc_task *task);
         void            (*set_retrans_timeout)(struct rpc_task *task);
@@ -238,6 +239,8 @@ int			xprt_reserve_xprt_cong(struct rpc_task *task);
 int                     xprt_prepare_transmit(struct rpc_task *task);
 void                    xprt_transmit(struct rpc_task *task);
 int                     xprt_adjust_timeout(struct rpc_rqst *req);
+void                    xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
+void                    xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
 void                    xprt_release(struct rpc_task *task);
 int                     xprt_destroy(struct rpc_xprt *xprt);
 
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 2d1e8b83dd68..e92ea99dd318 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -153,14 +153,42 @@ static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
         return retval;
 }
 
-
 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 {
         struct rpc_task *task;
+        struct rpc_rqst *req;
+
+        if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+                return;
+
+        task = rpc_wake_up_next(&xprt->resend);
+        if (!task) {
+                task = rpc_wake_up_next(&xprt->sending);
+                if (!task)
+                        goto out_unlock;
+        }
+
+        req = task->tk_rqstp;
+        xprt->snd_task = task;
+        if (req) {
+                req->rq_bytes_sent = 0;
+                req->rq_ntrans++;
+        }
+        return;
+
+out_unlock:
+        smp_mb__before_clear_bit();
+        clear_bit(XPRT_LOCKED, &xprt->state);
+        smp_mb__after_clear_bit();
+}
+
+static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
+{
+        struct rpc_task *task;
 
         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
                 return;
-        if (!xprt->nocong && RPCXPRT_CONGESTED(xprt))
+        if (RPCXPRT_CONGESTED(xprt))
                 goto out_unlock;
         task = rpc_wake_up_next(&xprt->resend);
         if (!task) {
@@ -168,7 +196,7 @@ static void __xprt_lock_write_next(struct rpc_xprt *xprt)
                 if (!task)
                         goto out_unlock;
         }
-        if (xprt->nocong || __xprt_get_cong(xprt, task)) {
+        if (__xprt_get_cong(xprt, task)) {
                 struct rpc_rqst *req = task->tk_rqstp;
                 xprt->snd_task = task;
                 if (req) {
@@ -183,11 +211,14 @@ out_unlock:
         smp_mb__after_clear_bit();
 }
 
-/*
- * Releases the transport for use by other requests.
+/**
+ * xprt_release_xprt - allow other requests to use a transport
+ * @xprt: transport with other tasks potentially waiting
+ * @task: task that is releasing access to the transport
+ *
+ * Note that "task" can be NULL.  No congestion control is provided.
  */
-static void
-__xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
+void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 {
         if (xprt->snd_task == task) {
                 xprt->snd_task = NULL;
@@ -198,11 +229,29 @@ __xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
         }
 }
 
-static inline void
-xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
+/**
+ * xprt_release_xprt_cong - allow other requests to use a transport
+ * @xprt: transport with other tasks potentially waiting
+ * @task: task that is releasing access to the transport
+ *
+ * Note that "task" can be NULL.  Another task is awoken to use the
+ * transport if the transport's congestion window allows it.
+ */
+void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+        if (xprt->snd_task == task) {
+                xprt->snd_task = NULL;
+                smp_mb__before_clear_bit();
+                clear_bit(XPRT_LOCKED, &xprt->state);
+                smp_mb__after_clear_bit();
+                __xprt_lock_write_next_cong(xprt);
+        }
+}
+
+static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 {
         spin_lock_bh(&xprt->transport_lock);
-        __xprt_release_write(xprt, task);
+        xprt->ops->release_xprt(xprt, task);
         spin_unlock_bh(&xprt->transport_lock);
 }
 
@@ -237,7 +286,7 @@ __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
                 return;
         req->rq_cong = 0;
         xprt->cong -= RPC_CWNDSCALE;
-        __xprt_lock_write_next(xprt);
+        __xprt_lock_write_next_cong(xprt);
 }
 
 /*
@@ -256,7 +305,7 @@ xprt_adjust_cwnd(struct rpc_xprt *xprt, int result)
                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
                 if (cwnd > RPC_MAXCWND(xprt))
                         cwnd = RPC_MAXCWND(xprt);
-                __xprt_lock_write_next(xprt);
+                __xprt_lock_write_next_cong(xprt);
         } else if (result == -ETIMEDOUT) {
                 cwnd >>= 1;
                 if (cwnd < RPC_CWNDSCALE)
@@ -693,7 +742,7 @@ void xprt_transmit(struct rpc_task *task)
                         task->tk_status = -ENOTCONN;
                 else if (!req->rq_received)
                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
-                __xprt_release_write(xprt, task);
+                xprt->ops->release_xprt(xprt, task);
                 spin_unlock_bh(&xprt->transport_lock);
                 return;
         }
@@ -792,7 +841,7 @@ void xprt_release(struct rpc_task *task)
         if (!(req = task->tk_rqstp))
                 return;
         spin_lock_bh(&xprt->transport_lock);
-        __xprt_release_write(xprt, task);
+        xprt->ops->release_xprt(xprt, task);
         __xprt_put_cong(xprt, req);
         if (!list_empty(&req->rq_list))
                 list_del(&req->rq_list);
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index fc4fbe8ea346..8589c1ad55e3 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1046,6 +1046,7 @@ static void xs_connect(struct rpc_task *task)
 static struct rpc_xprt_ops xs_udp_ops = {
         .set_buffer_size        = xs_udp_set_buffer_size,
         .reserve_xprt           = xprt_reserve_xprt_cong,
+        .release_xprt           = xprt_release_xprt_cong,
         .connect                = xs_connect,
         .send_request           = xs_udp_send_request,
         .set_retrans_timeout    = xprt_set_retrans_timeout_rtt,
@@ -1056,6 +1057,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
 static struct rpc_xprt_ops xs_tcp_ops = {
         .set_buffer_size        = xs_tcp_set_buffer_size,
         .reserve_xprt           = xprt_reserve_xprt,
+        .release_xprt           = xprt_release_xprt,
         .connect                = xs_connect,
         .send_request           = xs_tcp_send_request,
         .set_retrans_timeout    = xprt_set_retrans_timeout_def,