Pack zrlock_t by 8 bytes.

[amotin]

On FreeBSD this reduces this structure size from 64 to 56 bytes. dnode_handle_t respectively reduces from 72 to 64 bytes. It sounds like a waste to need 72 bytes to be able to relocate 808 bytes of dnode_t, which relocation on FreeBSD is not even supported.

How Has This Been Tested?

Built and booted with and without debug.

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.

[ryao]

There are around 5 more instances of this in the codebase if I recall correctly. Clang’s static analyzer will report them if you turn on this checker:

https://clang.llvm.org/docs/analyzer/checkers.html#id72

I had meant to write patches, but I have enough higher priority reports to handle that I have yet to make time to write patches for these. Since this catches one of them, I figure that I should point out that there are more and they are relatively easy to find.