Add support for ZFS mirror/striping

[ps-gill]

This pull request resolves issue #752

Summary:

• Updating ZFS driver to support multiple block devices and vdev types (mirror, raidz1 and raidz2). Default vdev type, stripe, is already supported.
• Updating ZFS driver docs on how to use the new config.

[stgraber]

General structure looks good, just a few styling nits and some smaller bits that need tweaking/fixing.

You should also add an extra commit, api: storage_zfs_vdev containing changes to both doc/api-extensions.md and internal/version/api.go introducing an API extension of that same name so API clients can detect that Incus supports the new syntax.

[stgraber]

Just did a quick rebase, merged two commits together and re-titled the commits as well as ran make static-analysis and fixed the 2-3 things that picked up.

Should be all good now, just waiting for Github to run all the tests.

Thanks!

[ps-gill]

The documentation test is failing due to vdev being lowercase and config (short for configuration). If you prefer, I can get those patched.

[stgraber]

Ah yeah, you probably need to escape vdev as it's not a dictionary word and config indeed needs to become configuration.

Please make those two edits directly in the doc commit then when things pass on Github I can merge it.

I'm on my phone for the rest of the day here so can't directly edit commits.

[ps-gill]

Ah yeah, you probably need to escape vdev as it's not a dictionary word and config indeed needs to become configuration.

Please make those two edits directly in the doc commit then when things pass on Github I can merge it.

I'm on my phone for the rest of the day here so can't directly edit commits.

It is done.

[stgraber]

The api-extensions.md fix needed to go in the api: commit, not the doc: commit, sorry :)

[ps-gill]

The api-extensions.md fix needed to go in the api: commit, not the doc: commit, sorry :)

Just fixed it.

Sorry, I should have done it that way the first time. A workflow where commit message and contents are tightly integrated with CI is new to me.