-struct asio_request *asio_get(struct asio_queue *q); // Get an empty request (not for writeback)
-struct asio_request *asio_get_writeback(struct asio_queue *q); // Get an empty writeback request
-void asio_turn_to_writeback(struct asio_request *r); // Convert a request allocated as non-writeback to writeback
-void asio_submit(struct asio_request *r); // Submit the request
+struct asio_request *asio_get(struct asio_queue *q); // Get an empty request
+void asio_submit(struct asio_request *r); // Submit the request (can block if too many writebacks)