dsl_dataset_space_written
err = dsl_dataset_space_written(fromds, ds,
err = dsl_dataset_space_written(prev, ds, written,
err = dsl_dataset_space_written(prev, ds, &written,
int dsl_dataset_space_written(dsl_dataset_t *oldsnap, dsl_dataset_t *new,
error = dsl_dataset_space_written(old, new,
error = dsl_dataset_space_written(old, new, &zc->zc_cookie,