Implement volume resizing

[AaronDewes]

Which issue(s) this PR fixes:

longhorn/longhorn#8022

What this PR does / why we need it:

Currently, SPDK volumes can not be resized. This aims at fixing this, and allows both growing and shrinking volumes.

Special notes for your reviewer:

I've not contributed to Longhorn before and this is completely untested. I'm trying to implement & test this feature, this is just a draft.

Additional documentation or context

[mergify]

This pull request is now in conflict. Could you fix it @AaronDewes? 🙏

[AaronDewes]

The approach this takes is that individual replicas are all resized. A RAID device in spdk should be automatically resized if all underlying devices grow (https://github.com/longhorn/spdk/blob/6925ca6543e4ad5a5e3a5db09217ae16bf939831/module/bdev/raid/bdev_raid.c#L2102).

[derekbit]

There is a dm linear device on the top of a device created by SPDK, so need to handle the dm device when expanding a volume.

[mergify]

This pull request is now in conflict. Could you fix it @AaronDewes? 🙏

[mergify]

This pull request is now in conflict. Could you fix it @AaronDewes? 🙏

[DamiaSan]

I didn't know that Aaron had already done this development, in the feature request ticket longhorn/longhorn#8022 there isn't any reference to this PR, so I understood that the development was to be done, as I actually did : longhorn/longhorn#8022 (comment).
At this point I prefer to proceed with my development on longhorn-spdk-engine and discard Aaron's one.
cc @derekbit

[derekbit]

I didn't know that Aaron had already done this development, in the feature request ticket longhorn/longhorn#8022 there isn't any reference to this PR

No worries, but the PRs are actually referenced in longhorn/longhorn#8022.

I didn't know that Aaron had already done this development, in the feature request ticket longhorn/longhorn#8022 there isn't any reference to this PR, so I understood that the development was to be done, as I actually did : longhorn/longhorn#8022 (comment). At this point I prefer to proceed with my development on longhorn-spdk-engine and discard Aaron's one. cc @derekbit

@DamiaSan Sure! You can proceed with your development, but the most important feature is delta rebuilding. Please co-work with @shuo-wu first.

If you don't have time for the volume expansion feature (best effort in v1.8.0), feel free to transfer to @c3y1huang. Thank you.

cc @innobead

[DamiaSan]

You can proceed with your development, but the most important feature is delta rebuilding. Please co-work with @shuo-wu first.

Yes I know, I only wanted to say that the apparent issue is solved and so the development can be completed without having other blocking tasks.

For delta rebuilding, I am actually creating into go-spdk-helper the new API for delta bitmap and for snapshot checksum. What about snapshot checksum in SPDK, I have to make a change to the PR based on a suggestion from Shuo.
What about the work on longhorn-spdk-engine, I don't know the status of the developments.

If you don't have time for the volume expansion feature (best effort in v1.8.0), feel free to transfer to @c3y1huang. Thank you.

As mentioned in the comment linked above longhorn/longhorn#8022 (comment), the work on types, go-spdk-helper and longhorn-spdk-engine has alredy been done and it is ready for the PR. What must be completed is the fix into SPDK, I have to finalize it and I don't think I can transfer it to Chin-Ya.