rbd: adds support for librbd rbd_resize2

[khayyamsaleem]

librbd exposes rbd_resize2, which allows clients to pass in a boolean controlling
whether or not the allocation should be allowed to shrink, and a progress-tracking
callback. This contribution extends go-ceph to be able to call rbd_resize2.

Closes #933

Signed-off-by: Khayyam Saleem khayyam.saleem@gmail.com

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
• Ran make api-update to record new APIs

New or infrequent contributors may want to review the go-ceph Developer's Guide including the section on how we track API Status and the API Stability Plan.

The go-ceph project uses mergify. View the mergify command guide for information on how to interact with mergify. Add a comment with @Mergifyio rebase to rebase your PR when github indicates that the PR is out of date with the base branch.

[phlogistonjohn]

I won't insist on it, but I'd like to suggest having the new function and test in new files. rbd.go is already fairly long. Having a dedicated file (and test!) focused on one or a few related things aids readability IMO.

[khayyamsaleem]

Thanks for the recommendation @phlogistonjohn ! Implemented.

[ansiwen]

@khayyamsaleem Thanks for the contribution. Please only add the new functions to a separate file. This is necessary, because the new API will be in preview mode first, which requires the build constraint //go:build ceph_preview at the top of the file (and also the according test file). Please see here for more information: https://github.com/ceph/go-ceph/blob/master/docs/development.md#documentation-conventions

[khayyamsaleem]

@phlogistonjohn @ansiwen should be ready for another round of review; thanks so much for your attention on this PR!

[phlogistonjohn]

@phlogistonjohn @ansiwen should be ready for another round of review; thanks so much for your attention on this PR!

Looking better, I've restarted the CI. There are two lingering issues that I think we should deal with: first, there are still changes to rbd.go, related to the changing of the comment block, that are now unnecessary. This may have been done by an IDE or the like but I'd prefer they remain unchanged by your PR. It's just "noise" when looking through the history of the project.

Second, and hopefully less work, is that it would be nice to squash your two commits together. We try to keep a long term history free of intermediate changes.

Let us (me) know if there are any questions on how to go about doing either one, and I'll try to help.

[khayyamsaleem]

Apologies for the slow turnaround here; this had fallen off my radar. Have rebased and squashed the commits and dropped the rbd.go changes. Thanks for your attention!

[phlogistonjohn]

LGTM now, thanks so much.

[khayyamsaleem]

@ansiwen looks like we'll need your additional review to push this through. Thanks again for helping get this PR in order.

[ansiwen]

LGTM, thanks!