Your pic would confuse anybody. You have to draw the currents being positive toward a node. (e.g. the + input of the OP amp.)
It does, try to make the inverting input, the same value as the non-inverting input. To do so, it has to feedback the current Irf. Again, assuming that toward the op amp (-) input is positive.
The output, is therefore -Irf. You can put a voltage on the (+) inp and get Vout=Vb-Irf
Vb or the bias voltage is impressed across the device. Vos of the OP amp is too. So, in I-V converter designs, Vos is important.