int (*read)(struct device*, void*, off_t, size_t);
int (*write)(struct device*, void*, off_t, size_t);
+ int (*read_async)(struct device*, void*, off_t, size_t);
+ int (*write_async)(struct device*, void*, off_t, size_t);
int (*read_page)(struct device*, void*, off_t);
int (*write_page)(struct device*, void*, off_t);