The last time this happened to me I was asked my altitude (which was something like 3500) and then asked to fly not above 2000 till advised. I agreed and started the descent rapido. In the meantime they asked my heading, gave me a turn for identification, but never told me I was identified, and in doing all this I had effectively stopped teaching so my student was paying for us to fly in a straight line for no purpose other than to save the airliner maybe 20 or 30 seconds of flight time.
To be honest I'd far rather have been given traffic info on the IFR then I could have judged for myself the best way of keeping out of his way horizontally and would have had useful cues for acquiring him visually - I could then have reported him visual and the controller would then have been able to get him through without the requirement for 5nm separation - "ABC123 traffic in your 2 o'clock 3 miles 500 feet below working this unit has you visual" or something of the sort.