SUNRPC: Clean up transport write space handling

Treat socket write space handling in the same way we now treat transport
congestion: by denying the XPRT_LOCK until the transport signals that it
has free buffer space.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

1 files changed, 11 insertions, 22 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index f54e8110f4c6..ef8d0e81cbda 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -440,20 +440,12 @@ out:
 	return err;
 }
 
-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--;
-}
-
 /**
- * xs_nospace - place task on wait queue if transmit was incomplete
+ * xs_nospace - handle transmit was incomplete
  * @req: pointer to RPC request
- * @task: task to put to sleep
  *
  */
-static int xs_nospace(struct rpc_rqst *req, struct rpc_task *task)
+static int xs_nospace(struct rpc_rqst *req)
 {
 	struct rpc_xprt *xprt = req->rq_xprt;
 	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
@@ -461,7 +453,8 @@ static int xs_nospace(struct rpc_rqst *req, struct rpc_task *task)
 	int ret = -EAGAIN;
 
 	dprintk("RPC: %5u xmit incomplete (%u left of %u)\n",
-			task->tk_pid, req->rq_slen - transport->xmit.offset,
+			req->rq_task->tk_pid,
+			req->rq_slen - transport->xmit.offset,
 			req->rq_slen);
 
 	/* Protect against races with write_space */
@@ -471,7 +464,7 @@ static int xs_nospace(struct rpc_rqst *req, struct rpc_task *task)
 	if (xprt_connected(xprt)) {
 		/* wait for more buffer space */
 		sk->sk_write_pending++;
-		xprt_wait_for_buffer_space(task, xs_nospace_callback);
+		xprt_wait_for_buffer_space(xprt);
 	} else
 		ret = -ENOTCONN;
 
@@ -569,7 +562,7 @@ static int xs_local_send_request(struct rpc_rqst *req, struct rpc_task *task)
 	case -ENOBUFS:
 		break;
 	case -EAGAIN:
-		status = xs_nospace(req, task);
+		status = xs_nospace(req);
 		break;
 	default:
 		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
@@ -642,7 +635,7 @@ process_status:
 		/* Should we call xs_close() here? */
 		break;
 	case -EAGAIN:
-		status = xs_nospace(req, task);
+		status = xs_nospace(req);
 		break;
 	case -ENETUNREACH:
 	case -ENOBUFS:
@@ -765,7 +758,7 @@ static int xs_tcp_send_request(struct rpc_rqst *req, struct rpc_task *task)
 		/* Should we call xs_close() here? */
 		break;
 	case -EAGAIN:
-		status = xs_nospace(req, task);
+		status = xs_nospace(req);
 		break;
 	case -ECONNRESET:
 	case -ECONNREFUSED:
@@ -1672,7 +1665,8 @@ static void xs_write_space(struct sock *sk)
 	if (!wq || test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &wq->flags) == 0)
 		goto out;
 
-	xprt_write_space(xprt);
+	if (xprt_write_space(xprt))
+		sk->sk_write_pending--;
 out:
 	rcu_read_unlock();
 }
@@ -2725,12 +2719,7 @@ static int bc_send_request(struct rpc_rqst *req, struct rpc_task *task)
 	 * Grab the mutex to serialize data as the connection is shared
 	 * with the fore channel
 	 */
-	if (!mutex_trylock(&xprt->xpt_mutex)) {
-		rpc_sleep_on(&xprt->xpt_bc_pending, task, NULL);
-		if (!mutex_trylock(&xprt->xpt_mutex))
-			return -EAGAIN;
-		rpc_wake_up_queued_task(&xprt->xpt_bc_pending, task);
-	}
+	mutex_lock(&xprt->xpt_mutex);
 	if (test_bit(XPT_DEAD, &xprt->xpt_flags))
 		len = -ENOTCONN;
 	else