How much rent are you legally responisble for?

How much rent are you legally responisble for???
I an purchasing a home and have given my landlord sufficient notice. I informed him that in the event I moved in the middle of the month I would pay for the time I was still on the premises (partial rent for days unit is occupied). My landlord in turn informs me that the entire amount of rent is due for each month I am in residence be it 1 day or or 30. In addition he wants to do the ”walk-thru” while I am still in residence. Is any of this legal under California law. I have a month to month lease and my rent is up to date.