Linux 7.2 compat

[robn]

[Sponsors: TrueNAS]

Motivation and Context

They revamped the airport completely
Now it looks just like a nightclub
Everyone's excited and confused

– Man, It's So Loud In Here, They Might Be Giants, 2001.

Getting a head start on 7.2 support. Current target: next-20260622

I'll update this as we get closer, and take it out of draft once 7.2-rc1 appears in a couple of weeks.

Description

• replace sget() with sget_fc(), and update zpl_test_super() to match the new signature.

How Has This Been Tested?

ZTS run completed: next-20260612, next-20260622.

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)
• Quality assurance (non-breaking change which makes the code more robust against bugs)
• 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.