这是struct的怎么个用法???

static struct ioengine_ops ioengine = {
    .name        = "mmap",
    .version    = FIO_IOOPS_VERSION,
    .init        = fio_mmapio_init,
    .prep        = fio_mmapio_prep,
    .queue        = fio_mmapio_queue,
    .open_file    = generic_open_file,
    .close_file    = generic_close_file,
    .get_file_size    = generic_get_file_size,
    .flags        = FIO_SYNCIO | FIO_NOEXTEND,
};