我如何通过python pandas从特定点反向计算天数？

import pandas as pd
from datetime import datetime, timedelta

df = pd.DataFrame({'date': pd.date_range(start='2022-01-01', end='2022-01-31')})

specific_date = datetime(2022, 1, 15)

df['days_diff'] = (specific_date - df['date']).dt.days