Comment 22 for bug 1824407

While there may be arguments for synthesizing UUIDs in various fs drivers, or creating them in the first place in fs-creation tools, I agree that if overlayfs has a hard dependency on UUIDs for uniquely identifying layers, it needs to fill in the gaps where the previous tools/drivers failed to provide.

So, yeah, I think Colin's on the right track here with making overlayfs itself fix its own use-case, which will cover any future filesystem/tool that otherwise fails to UUID itself.

My only review of the above is that you might want to mix a monotonic or random seed in with your superblock when generating your fake UUIDs, in case someone does something like stacking multiple empties on top of each other, or some other madness where you effectively have the same superblock more than once at the RO level, but need to identify them as different.