# Find gain of this common-gate

I have a large circuit involving feedback as follows

I am trying to find the closed-loop gain of this. Before I can do that, I need to find the open-loop gain. Thus, removing the feedback loop, M2 becomes useless and I am left with a common-gate stage below

Now, I need to find the gain of this circuit Vout/Iin and I make the following small-signal model

I can't seem to get Vout/Iin from this. Any ideas?