Refactor zvol in to platform and platform independent bits

[mattmacy]

Signed-off-by: Matt Macy [email protected]

Motivation and Context

Description

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)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted and contain Signed-off-by.

[allanjude]

Reviewed By: Allan Jude [email protected]

[behlendorf]

Thanks for tackling this further refactoring. Before we move ahead with this I'd like to investigate using a slightly more traditional approach and have the platform specific code register callbacks with the common code. The common code would then only need to provide platform independent functionality and all the Linux/FreeBSD/MacOS/ specific code/headers could be private. I'm happy to help hash out any design details.

[codecov]

Codecov Report

Merging #9295 into master will decrease coverage by 12.37%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master    #9295       +/-   ##
===========================================
- Coverage   79.06%   66.68%   -12.38%     
===========================================
  Files         401      325       -76     
  Lines      122495   105116    -17379     
===========================================
- Hits        96846    70100    -26746     
- Misses      25649    35016     +9367

Flag	Coverage Δ
#kernel	?
#user	66.68% <100%> (+0.05%)	⬆️

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[behlendorf]

@ikozhukhov @lundman would you mind looking at this proposed refactoring to see if it's flexible enough to accommodate your platforms.

[ghost]

Rebased and changed void (*zv_free)(void *) to void (*zv_free)(zvol_state_t *) (and adjusted accordingly in the two places affected by this).

[ghost]

void set_disk_ro -> static void zvol_set_disk_ro_impl
void set_capacity -> static void zvol_set_capacity_impl
Eliminated some reordering diffs.
No functional changes.

[behlendorf]

The Amazon Linux 2 bot hit #9357 which appears to be a existing issue. Regardless, I've resubmitted that build for good measure.

[lundman]

Oh I like this idea

[lundman]

Biggest changes for us is that we call C++/IOkit to create/remove the device node(s), which has to be named /dev/disk - we are nice and create symlinks for users as to maintain /var/run/zfs/dsk/$pool/$zvol - but since we can't create symlinks in kernel, we talk to zed to do that. Rename is just re-creating symlinks. But all of that should fit into zvol_os.c (and our own zvolIO.cpp) nicely. The code that looks inside uio has also moved into zvol_os.c so that is a bonus for us (as it is opaque on osx).
This will be much nicer, I look forward to attacking it locally.

[ikozhukhov]

well, will see how to try to use/reuse it with dilos builds
thanks for update!

[behlendorf]

@lundman @ikozhukhov thanks for making the time to look this over. I'll go ahead and get this merged once the bots wrap up their testing.