Curtin creates filesystems with incorrect flags for some distributions

[Boris Lukashev]

When deploying a RHEL7-derived operating system through MaaS, we found that the deployed host could not resize its own EXT4 filesystem due to the FS having been created by the provisioning image (Focal). The ephemeral has a newer userspace (and kernel) ABI than RHEL7, newer FS utils with options added after that team proclaimed "stable," and the flags its sets on the target FS make it impossible for the resulting deployment to edit its filesystems.

Ideally, MaaS would tell Curtin which FS options to enable for all applied filesystems, which would permit specifying compatibility options for older deploy targets; and help ZFS adoption since the way zfsroot is implemented currently eliminates all advantages of the filesystem other than hash-tree-validated transactional CoW and a slightly smarter cache.

[Lee Trager (ltrager)]

The difficultly MAAS/Curtin has is it doesn't know which kernel supports which features. We've discussed developing a detection method but that would most likely lead to a support matrix within MAAS which will quickly become stale. We've also discussed allowing users to specify which options are enabled/disabled but that hasn't been added to the roadmap yet.

For now I would suggest changing the commissioning release to Bionic or Xenial. This should work around the issues you are seeing.

[Adam Collard (adam-collard)]

Thank you for reporting this issue - we are tracking this internally using PF-3237, and closing the bug in favour of that.

Note that Curtin has recently gained support for some of this modelling.