+ /*
+ * Efficiently zero a region of the disk image. Typically an image format
+ * would use a compact metadata representation to implement this. This
+ * function pointer may be NULL and .bdrv_co_writev() will be called
+ * instead.
+ */
+ int coroutine_fn (*bdrv_co_write_zeroes)(BlockDriverState *bs,
+ int64_t sector_num, int nb_sectors);