SUNRPC: Add a transport callback to handle dequeuing of an RPC request

Add a transport level callback to allow it to handle the consequences of
dequeuing the request that was in the process of being transmitted.
For something like a TCP connection, we may need to disconnect if the
request was partially transmitted.

Signed-off-by: Trond Myklebust <[e-mail]>

include/linux/sunrpc/xprt.h

···
 	int		(*prepare_request)(struct rpc_rqst *req,
 					   struct xdr_buf *buf);
 	int		(*send_request)(struct rpc_rqst *req);
+	void		(*abort_send_request)(struct rpc_rqst *req);
 	void		(*wait_for_reply_request)(struct rpc_task *task);
 	void		(*timer)(struct rpc_xprt *xprt, struct rpc_task *task);
 	void		(*release_request)(struct rpc_task *task);

net/sunrpc/xprt.c

···
 	if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
 		return;
 	if (!list_empty(&req->rq_xmit)) {
+		struct rpc_xprt *xprt = req->rq_xprt;
+
+		if (list_is_first(&req->rq_xmit, &xprt->xmit_queue) &&
+		    xprt->ops->abort_send_request)
+			xprt->ops->abort_send_request(req);
+
 		list_del(&req->rq_xmit);
 		if (!list_empty(&req->rq_xmit2)) {
 			struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,

net/sunrpc/xprtsock.c

···
 	return xdr_alloc_bvec(buf, rpc_task_gfp_mask());
 }
 
+static void xs_stream_abort_send_request(struct rpc_rqst *req)
+{
+	struct rpc_xprt *xprt = req->rq_xprt;
+	struct sock_xprt *transport =
+		container_of(xprt, struct sock_xprt, xprt);
+
+	if (transport->xmit.offset != 0 &&
+	    !test_bit(XPRT_CLOSE_WAIT, &xprt->state))
+		xprt_force_disconnect(xprt);
+}
+
 /*
  * Determine if the previous message in the stream was aborted before it
  * could complete transmission.
···
 	.buf_free		= rpc_free,
 	.prepare_request	= xs_stream_prepare_request,
 	.send_request		= xs_local_send_request,
+	.abort_send_request	= xs_stream_abort_send_request,
 	.wait_for_reply_request	= xprt_wait_for_reply_request_def,
 	.close			= xs_close,
 	.destroy		= xs_destroy,
···
 	.buf_free		= rpc_free,
 	.prepare_request	= xs_stream_prepare_request,
 	.send_request		= xs_tcp_send_request,
+	.abort_send_request	= xs_stream_abort_send_request,
 	.wait_for_reply_request	= xprt_wait_for_reply_request_def,
 	.close			= xs_tcp_shutdown,
 	.destroy		= xs_destroy,