Use kmap_local_page instead of kmap_atomic

[calccrypto]

Motivation and Context

In Linux Kernel 5.11, kmap_atomic() was deprecated in favor of kmap_local_page().

Description

Changed

#define zfs_kmap_atomic(page)   kmap_atomic(page)
#define zfs_kunmap_atomic(addr) kunmap_atomic(addr)

to

#define	zfs_kmap_local(page)	kmap_local_page(page)
#define	zfs_kunmap_local(addr)	kunmap_local(addr)

for kernels that have kmap_local_page().

How Has This Been Tested?

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.

[amotin]

This seems to conflict with #10018, already having zfs_kmap()/zfs_kunmap(). I'd either kept it as _atomic, or made _local().

[calccrypto]

I've changed the macros to zfs_kmap_temp and zfs_kunmap_temp to reflect the temporary nature of the mappings as described in High Memory Handling.

[amotin]

I'll let others decide, but to me _local has pretty specific meaning -- it is local to this thread/CPU. Definition of temporary is much less specific, plus it is different from kernel and so confusing, plus you have to use abbreviation.

[calccrypto]

Changed to _local