XFS Quota dynamic adjustment

[trathborne]

Describe the problem/challenge you have
XFS Quotas are set only once when the PV is created. If I want to change the quota for a PV, I can't just change the value in a resource. I have to log in to the Node and use xfs_quota to change the quota, and I bet that change doesn't bubble back up to OpenEBS/K8s.

Describe the solution you'd like
I would like to be able to change the size of the storage request in the parent Pod (or above, not sure of the exact flow of CSI) and when it changes in the PV/PVC, the XFS quota is adjusted by the operator via the same mechanism it used to initially configure the quota. If the request cannot be fulfilled because the quota is being reduced below the current usage or the quota is larger than the filesystem (or total quota in the filesystem is over some overcommit threshold), this should be reported in an Event and the Pod/PV should remain inconsistent. (Uh, or whatever is the best practice in K8s ☺)

Environment:

• OpenEBS version: 3.0.0
• Kubernetes version: v1.19.2 and I am embarrassed about it
• Cloud provider or hardware configuration: Proxmox VMs on amd64
• OS: Debian 10 or 11
• kernel ... 4.19 / 5.10 because Debian versions

[fixed77]

I would like to see the quota change also for ext4

[niladrih]

The solution proposed in @trathborne's comment seems like could be done. I'd have to test this one before I can concoct a design proposal for it.

[opipenbe]

I think such feature would be a game changer for this project.

[avishnu]

Scoping for design in v4.3.