Intermittent superblock checksum mismatch during resize2fs

[Dimitri John Ledkov]

This was causing us headaches like since forever. Our reproducers were very
intermittent to catch it. I think we might want to backport this everywhere
we can.

On Thu, 5 Oct 2023, 17:50 Krister Johansen, <kjlx at templeofstupid.com> wrote:

> Hi,
> My team runs Ubuntu 20.04 on EC2.  We use the cloud images that
> Canonical and AWS publish for Ubuntu as our base image.  As part of
> the first boot of one of these images, cloud-init runs resiz2fs in order
> to make the root filesystem match the size of the root volume on which the
> instance is provisioned.
>
> A few times a week, this would fail for us, which results in instances
> that have an unexpectedly small root filesystem.  We were able to build
> a reproducer for the problem, debug it, and get it fixed upstream.
> There's a patch in the main branch of e2fsprogs with the fix now.
>
> We've had to fork the Ubuntu version of e2fsprogs to carry this patch,
> but from our analysis it ought to impact (potentially) any customer
> running on EC2.  Would Ubuntu be willing to backport this patch to the
> versions for which they build EC2 AMIs?  (We're specifically interested
> in any LTS Ubuntu releases).
>
> I logged a ticket for this on launchpad here (it includes the
> reproducer):
>
> https://bugs.launchpad.net/ubuntu/+source/e2fsprogs/+bug/2036467
>
> The patch itself is a 2-line change:
>
>
> https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/?id=43a498e938887956f393b5e45ea6ac79cc5f4b84
>
> The thread where this was discussed with the upstream maintainer is
> here:
>
> https://lore.kernel.org/linux-ext4/20230609042239.GA1436857@mit.edu/
>
> Thanks very much,
>
> -K
>
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