/* low level (fnctl) lock functions. */
int (*lock_fn)(int fd, int rw, off_t off, off_t len, bool w, void *);
int (*unlock_fn)(int fd, int rw, off_t off, off_t len, void *);
void *lock_data;
/* low level (fnctl) lock functions. */
int (*lock_fn)(int fd, int rw, off_t off, off_t len, bool w, void *);
int (*unlock_fn)(int fd, int rw, off_t off, off_t len, void *);
void *lock_data;