offset_to_bit
start = offset_to_bit(info->offset, unit, offset);
start = offset_to_bit(info->offset, unit, offset);
i = offset_to_bit(bitmap_info->offset, unit,
i = offset_to_bit(bitmap->offset, unit, end);
i = offset_to_bit(bitmap->offset, unit, info->offset) - 1;
i = offset_to_bit(entry->offset, unit,