[2.3.2] Revert "zinject: count matches and injections for each handler"

[robn]

Motivation and Context

2.3.1 introduced a userspace/kernel ABI break that I missed. As a result, 2.3.1 userspace tools are incompatible with <2.3.1 kernel modules for many tasks.

After I updated userspace to 2.3.1, zfs send started returning EINVAL, and zfs events returned EBADF. I rebooted and didn't think much of it; my local machine is weird sometimes.

Later I noticed why: the "match counts" change adds a couple of fields to zinject_record_t. There's one of those embedded in the middle of zfs_cmd_t. zc_cleanup_fd and some of the send params both occur after that field. The kernel and userspace were running on different layouts, so couldn't find what they needed.

I don't know if you want to revert the change and cut a 2.3.2 release. If you do, this is the revert. It might be unnecessary though. depends how long before folks can reboot.

(also, an apology from me: feels like something I should have noticed. I'm gonna go put some compile time size checks on a few things to hopefully help prevent this next time).

Description

Adding fields to zinject_record_t unexpectedly extended zfs_cmd_t, preventing some things working properly with 2.3.1 userspace tools against 2.3.0 kernel module.

This reverts commit fabdd50.

How Has This Been Tested?

Compile checked only.

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.

[vedranmiletic]

Not everybody upgrades immediately after a release comes out, so it might be worth it.

[amotin]

If it affects things outside of zinject itself (I hoped it won't) and we will to release 2.3.2 soon enough, then it makes sense.