int (*prep)(struct thread_data *, struct io_u *);
enum fio_q_status (*queue)(struct thread_data *, struct io_u *);
int (*commit)(struct thread_data *);
int (*prep)(struct thread_data *, struct io_u *);
enum fio_q_status (*queue)(struct thread_data *, struct io_u *);
int (*commit)(struct thread_data *);