Comment 24 for bug 1824407

I thought all lowerdirs must be read-only, and the first one in the stack
will win. Even if there are same ones down the stack it shouldn't matter.
But I guess needs testing.

I wouldn't want to use random, as that will eat entropy on early boot of
Ubuntu Core systems.

Do we need a separate upstream issue to create uuid in the squashfs
Superblock?

On Wed, 6 Nov 2019, 21:21 Adam Conrad, <adconrad@0c3.net> wrote:

> 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.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1824407
>
> Title:
> remount of multilower moved pivoted-root overlayfs root, results in
> I/O errors on some modified files
>
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