+/**
+ * struct io_plan - one half of I/O to do
+ * @status: the status of this plan.
+ * @io: function to call when fd becomes read/writable, returns 0 to be
+ * called again, 1 if it's finished, and -1 on error (fd will be closed)
+ * @next: the next function which is called if io returns 1.
+ * @next_arg: the argument to @next
+ * @u1, @u2: scratch space for @io.
+ */
+struct io_plan {
+ enum io_plan_status status;
+
+ int (*io)(int fd, struct io_plan_arg *arg);
+
+ struct io_plan *(*next)(struct io_conn *, void *next_arg);