Document grub2 compatibility updates and test for all feature sets

[usaleem-ix]

Motivation and Context

grub2 compatibility list has been updated. zpool-features.7 should be updated accordingly.

Adding a new feature to compatibility list also enables all its dependencies. It may potentially
enable any feature which is not present in compatibility list. We should test for all know feature
sets and make sure only those features are enabled that are present in compatibility list.

Description

zpool-features.7 is updated to reflect updates in grub2 compatibility list.

zpool_create_features_007.ksh tests for compat-2020 feature set, that it only enables the
features that are listed in compat-2020. zpool_create_features_007.ksh is updated to test
for all known feature sets.

There was a fallout after updating the test, openzfsonosx-1.8.1 lists encryption to be enabled,
encryption depends on bookmark_v2 feature which is also enabled, but not listed in
openzfsonosx-1.8.1 list. So, encryption has been removed from openzfsonosx-1.8.1.

How Has This Been Tested?

A successful ZTS run after the updates.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[rincebrain]

That change might be incorrect.

bookmark_v2 was added as a dependency after yet another way encryption was broken was found, so it's possible that OpenZFS on OSX 1.8.1 doesn't support bookmark_v2, and consequently, trying to use that compatibility mode to enable that would break using that version, and the more correct choice would be to just drop encryption as an allowed feature there.

[usaleem-ix]

Thank you @rincebrain, I was not exactly sure if adding bookmark_v2 is the right thing to do here.

@lundman would you please suggest if removing encryption from the feature list for OpenZFS on OSX 1.8.1 would be alright?

[rincebrain]

This might be also bad historically even more than there - for example, 0.8 got bookmark_v2 in 0.8.4 (if I recall), so do we want the compatibility setting to not work except for 0.8.4-6?

Hm, I'm not actually sure if that's correct any more now. Maybe it went in before 0.8 final release, but I thought there was some caveat about hard requiring it coming later that meant I kept seeing people at the time complaining about the errata 4 message when they didn't get it before...

[usaleem-ix]

Instead of adding bookmark_v2, I have removed encryption from the feature set for OpenZFS on OSX 1.8.1. Let's see what other people think about it.

[behlendorf]

Instead of adding bookmark_v2, I have removed encryption from the feature set for OpenZFS on OSX 1.8.1. Let's see what other people think about it.

This seems like the safest thing to do. However, according to these release notes the bookmark_v2 feature was included in 1.8.1.