Fix growpart race

[holmanb]

Proposed Commit Message

Fixes #4613

Additional Context

See bug

Checklist

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

Merge type

• Squash merge using "Proposed Commit Message"
• Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[TheRealFalcon]

2 minor comments inline.

Can we make sure this is unit tested?

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging TheRealFalcon, and he will ensure that someone takes a look soon.

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[TheRealFalcon]

@holmanb No rush on this, but I was waiting for unit tests before re-review.

[holmanb]

Thanks @TheRealFalcon. This one fell off my radar - in part due to test complexity.

resize_devices() will require lots of mocks in order to get coverage for the log message logic - enough that I don't think that such a heavily mocked test provides much value. Refactoring that function would likely be required to make it more reasonable to write tests for, but I'm hoping to avoid that for now.

I've pushed a test for get_size(), let me know if that suffices for now.

[TheRealFalcon]

Yeah, that one's a bit of a doozy. Given that we have some integration test coverage (that triggered this issue), I'm ok skipping that function for now.