repart: Value too large for defined data type

[Thayne Harbaugh <thayne@xxxxxxxxxxxxxxxx>]

Greetings,

I have a mkosi build that is failing with the following message:

  >$ mkosi build
  ...
  /var/tmp/.#repart020c1a929b048b02 successfully formatted as ext4 (label "root", uuid c8ed6cd3-04b0-4667-8f2f-af9487b8b986)
  Automatically determined minimal disk image size as 2.2G.
  Sized '/home/thayne/.cache/mkosi/mkosi-workspace-37l8iaf4/staging/test_1.2.3.raw' to 2.2G.
  Applying changes to /home/thayne/.cache/mkosi/mkosi-workspace-37l8iaf4/staging/test_1.2.3.raw.
  Failed to read file attributes of /home/thayne/.cache/mkosi/mkosi-workspace-37l8iaf4/staging/test_1.2.3.raw: Value too large for defined data type
  ? "systemd-repart --empty=allow --size=auto --dry-run=no --json=pretty --no-pager --offline=yes --seed 1feaec73-f24d-454c-bd15-4f80926e951e /home/thayne/.cache/mkosi/mkosi-workspace-37l8iaf4/staging/test_1.2.3.raw --root=/buildroot --empty=create --defer-partitions esp,xbootldr --generate-fstab=/etc/fstab --generate-crypttab=/etc/crypttab --definitions /source/mkosi.repart" returned non-zero exit code 1.

It is a build that has been running without problems for some time.
Recently it has changed from incorporating systemd v256 to v257.  When
I switch it back to v256 it succeeds and does not error.  I have tried
to narrow it further.

  * The build runs inside of a Docker container with the mkosi source
    triee mounted inside.  The container is started with the following
    command:

      >$ docker run -it --privileged -v "/dir/to/source:/source" ubuntu:24.04

  * The container has mkosi 24.3 inside

  * The failure occurs with both erofs+best and ext4+guess

  * The mkosi configuration is the following:

      mkosi.conf
      ==========

        [Distribution]
        Distribution=ubuntu
        # noble == 24.04
        Release=noble
        Repositories=noble,noble-security,noble-updates
        Architecture=x86-64

        [Output]
        Format=disk
        ImageId=test
        ImageVersion=1.2.3

        [Content]
        RootPassword=tomato
        Bootable=yes
        Bootloader=systemd-boot

        Packages=
                linux-image-6.8.0-51-generic

      mkosi.repart/10-esp.conf
      ========================

        [Partition]
        Type=esp
        Format=vfat
        CopyFiles=/boot:/
        CopyFiles=/efi:/
        SizeMinBytes=2048M

      mkosi.repart/20-rootfs.conf
      ===========================

        [Partition]
        Type=root
        Label=root
        #Format=erofs
        #Minimize=best
        Format=ext4
        Minimize=guess
        MountPoint=/:ro
        CopyFiles=/:/
        ReadOnly=on
        Encrypt=key-file
        EncryptedVolume=root:/run/fscrypt.sock:luks,headless,x-initrd.attach

While initially the failure seemed to correclate directly with systemd
v257 packages being injected into mkosi.packages I have since been
able to reproduce the failure with the upstream Ubuntu 24.04/noble
v255 version of systemd.

It seems that building on a mount inside of a Docker container is
necessary factor to cause the failure.  While I have made a quick
glance at src/repart/repart.c in prepare_temporary_file(),
context_split() and context_minimize() I have not done any serious
digging yet.

Any ideas about the specifics of what causes this failure and what it
will take to fix it?