int row_is_invalid(struct osl_table *t, uint32_t row_num);
int get_mapped_object(const struct osl_table *t, unsigned col_num,
uint32_t row_num, struct osl_object *obj);
-int para_truncate(const char *filename, off_t size);
int unmap_table(struct osl_table *t, enum osl_close_flags flags);
int init_rbtrees(struct osl_table *t);