On Thu, Aug 27, 2020 at 10:29:05AM +0300, Amir Goldstein wrote: > I figured you'd say something like that :) > but since we are talking about dm-thin as a solution for predictable > behavior at the moment and this sanity check helps avoiding adding > new tests that can fail to some extent, is the proposed bandaid good enough > to keep those tests alive until a better solution is proposed? Well, the problem is that a test that wants to reliable nuke data needs to... *drumroll* reliably nuke data. Which means zeroing or at least a known pattern. discard doesn't give you that. I don't see how a plain discard is going to work for any file system for that particular case.