9P: Add cancelled() to the transport functions.

And move transport-specific code out of net/9p/client.c

Signed-off-by: Simon Derr <simon.derr@bull.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/include/net/9p/transport.h b/include/net/9p/transport.h
index 9a36d92..d9fa68f 100644
--- a/include/net/9p/transport.h
+++ b/include/net/9p/transport.h
@@ -40,6 +40,8 @@
  * @close: member function to discard a connection on this transport
  * @request: member function to issue a request to the transport
  * @cancel: member function to cancel a request (if it hasn't been sent)
+ * @cancelled: member function to notify that a cancelled request will not
+ *             not receive a reply
  *
  * This is the basic API for a transport module which is registered by the
  * transport module with the 9P core network module and used by the client
@@ -58,6 +60,7 @@
 	void (*close) (struct p9_client *);
 	int (*request) (struct p9_client *, struct p9_req_t *req);
 	int (*cancel) (struct p9_client *, struct p9_req_t *req);
+	int (*cancelled)(struct p9_client *, struct p9_req_t *req);
 	int (*zc_request)(struct p9_client *, struct p9_req_t *,
 			  char *, char *, int , int, int, int);
 };