SUNRPC: Simplify xprt_prepare_transmit()

Remove the checks for whether or not we need to transmit, and whether
or not a reply has been received. Those are already handled in
call_transmit() itself.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/xprt.c

@@ -1123,27 +1123,18 @@ bool xprt_prepare_transmit(struct rpc_task *task)
 {
 	struct rpc_rqst	*req = task->tk_rqstp;
 	struct rpc_xprt	*xprt = req->rq_xprt;
-	bool ret = false;
 
 	dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 
-	spin_lock_bh(&xprt->transport_lock);
-	if (!req->rq_bytes_sent) {
-		if (req->rq_reply_bytes_recvd) {
-			task->tk_status = req->rq_reply_bytes_recvd;
-			goto out_unlock;
-		}
+	if (!xprt_lock_write(xprt, task)) {
+		/* Race breaker: someone may have transmitted us */
 		if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
-			goto out_unlock;
-	}
-	if (!xprt->ops->reserve_xprt(xprt, task)) {
-		task->tk_status = -EAGAIN;
-		goto out_unlock;
+			rpc_wake_up_queued_task_set_status(&xprt->sending,
+					task, 0);
+		return false;
+
 	}
-	ret = true;
-out_unlock:
-	spin_unlock_bh(&xprt->transport_lock);
-	return ret;
+	return true;
 }
 
 void xprt_end_transmit(struct rpc_task *task)