struct io_u *(*event)(struct thread_data *, int);
int (*cancel)(struct thread_data *, struct io_u *);
void (*cleanup)(struct thread_data *);
int (*open_file)(struct thread_data *, struct fio_file *);
int (*close_file)(struct thread_data *, struct fio_file *);
int (*invalidate)(struct thread_data *, struct fio_file *);
struct io_u *(*event)(struct thread_data *, int);
int (*cancel)(struct thread_data *, struct io_u *);
void (*cleanup)(struct thread_data *);
int (*open_file)(struct thread_data *, struct fio_file *);
int (*close_file)(struct thread_data *, struct fio_file *);
int (*invalidate)(struct thread_data *, struct fio_file *);