rados: Implement rados_set_alloc_hint2

[okhoshi]

Signed-off-by: Quentin Devos 4972091+Okhoshi@users.noreply.github.com

Add support in go-ceph:

• rados_set_alloc_hint2
• rados_write_op_set_alloc_hint2

Closes #697

Checklist

• Added tests for features and functional changes
• Public functions and types are documented
• Standard formatting is applied to Go code
• Is this a new API? Added a new file that begins with //go:build ceph_preview

I'm not sure how I'm supposed to test the Allocation Hint, especially since I'm not aware of a way to check the Allocation hints set on a file, and that the functions never return errors.

[phlogistonjohn]

I'm not sure how I'm supposed to test the Allocation Hint, especially since I'm not aware of a way to check the Allocation hints set on a file, and that the functions never return errors.

Heh. That's unfortunate. I suppose we can just add a few calls to the function with 2-3 of the various flags along with some other ops. This way we at least see that it doesn't segfault or anything like that. It's not the best test in the world but IMO better than nothing. Can you please do something like that? Once done, I can activate the CI and we'll be sure it compiles and executes even if we can't assert anything about it beyond that.

[okhoshi]

Hey @phlogistonjohn, I added the tests you suggested 👍

[phlogistonjohn]

Looks good to me, thanks!

Pull request has been modified.

[phlogistonjohn]

LGTM thanks!

[ansiwen]

LGTM