RPC: allow call_encode() to delay transmission of an RPC call.

 Currently, call_encode will cause the entire RPC call to abort if it returns
 an error. This is unnecessarily rigid, and gets in the way of attempts
 to allow the NFSv4 layer to order RPC calls that carry sequence ids.

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

include/linux/sunrpc/xprt.h

@@ -211,6 +211,7 @@ int			xprt_reserve_xprt(struct rpc_task *task);
 int			xprt_reserve_xprt_cong(struct rpc_task *task);
 int			xprt_prepare_transmit(struct rpc_task *task);
 void			xprt_transmit(struct rpc_task *task);
+void			xprt_abort_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);

net/sunrpc/clnt.c

@@ -678,13 +678,11 @@ call_allocate(struct rpc_task *task)
 static void
 call_encode(struct rpc_task *task)
 {
-	struct rpc_clnt	*clnt = task->tk_client;
 	struct rpc_rqst	*req = task->tk_rqstp;
 	struct xdr_buf *sndbuf = &req->rq_snd_buf;
 	struct xdr_buf *rcvbuf = &req->rq_rcv_buf;
 	unsigned int	bufsiz;
 	kxdrproc_t	encode;
-	int		status;
 	u32		*p;
 
 	dprintk("RPC: %4d call_encode (status %d)\n", 
@@ -712,12 +710,9 @@ call_encode(struct rpc_task *task)
 		rpc_exit(task, -EIO);
 		return;
 	}
-	if (encode && (status = rpcauth_wrap_req(task, encode, req, p,
-						 task->tk_msg.rpc_argp)) < 0) {
-		printk(KERN_WARNING "%s: can't encode arguments: %d\n",
-				clnt->cl_protname, -status);
-		rpc_exit(task, status);
-	}
+	if (encode != NULL)
+		task->tk_status = rpcauth_wrap_req(task, encode, req, p,
+				task->tk_msg.rpc_argp);
 }
 
 /*
@@ -865,17 +860,23 @@ call_transmit(struct rpc_task *task)
 	if (task->tk_status != 0)
 		return;
 	/* Encode here so that rpcsec_gss can use correct sequence number. */
-	if (!task->tk_rqstp->rq_bytes_sent)
+	if (task->tk_rqstp->rq_bytes_sent == 0) {
 		call_encode(task);
-	if (task->tk_status < 0)
-		return;
+		/* Did the encode result in an error condition? */
+		if (task->tk_status != 0)
+			goto out_nosend;
+	}
 	xprt_transmit(task);
 	if (task->tk_status < 0)
 		return;
 	if (!task->tk_msg.rpc_proc->p_decode) {
 		task->tk_action = NULL;
 		rpc_wake_up_task(task);
 	}
+	return;
+out_nosend:
+	/* release socket write lock before attempting to handle error */
+	xprt_abort_transmit(task);
 }
 
 /*

net/sunrpc/xprt.c

@@ -709,6 +709,14 @@ int xprt_prepare_transmit(struct rpc_task *task)
 	return err;
 }
 
+void
+xprt_abort_transmit(struct rpc_task *task)
+{
+	struct rpc_xprt	*xprt = task->tk_xprt;
+
+	xprt_release_write(xprt, task);
+}
+
 /**
  * xprt_transmit - send an RPC request on a transport
  * @task: controlling RPC task