def METHOD_NAME(self, vol):
    """
    The physical free blocks of a specified volumne
    Args:
        vol (str): The vdo volumne name specified
    Returns:
        int: Returns size of physical free
    """
    return (self.get_physical_blocks_of_vol(vol) -
            self.get_overhead_used_of_vol(vol) -
            self.get_physical_used_of_vol(vol))