+/**
+ * io_time_override - override the normal call for time.
+ * @nowfn: the function to call.
+ *
+ * io usually uses time_now() internally, but this forces it
+ * to use your function (eg. for debugging). Returns the old
+ * one.
+ */
+struct timeabs (*io_time_override(struct timeabs (*now)(void)))(void);
+