Comment 12 for bug 1566622

As far as I know I don't think there is a key we can use. I see that the attach_volume / detach_volume also take a mountpoint, which is used as the unique key - is that anywhere in the block device info? In which case, it would be good to use the same logic as detach.

I would think that the existing method to calculate the name (new style first, fall back to old style) would be fine as a fall back.