Volume partitions are not supported

[jsafrane]

/kind bug

What happened?
For CSI migration we need all in-tree features supported in the CSI driver. In-tree volumes support mounting volume partitions in pv.spec.awsElasticBlockStore.partition flag. Such capability should be present in the CSI driver too.

How to reproduce it (as minimally and precisely as possible)?
Enable CSI migration and use following Pod:

apiVersion: v1
kind: Pod
metadata:
  name: inline
spec:
  containers:
  - name: inline
    image: centos:7
    args:
    - sleep
    - '99999'
    volumeMounts:
    - mountPath: "/mnt/storage"
      name: inline
  volumes:
  - name: inline
    awsElasticBlockStore:
      fsType: xfs
      volumeID: vol-072b2b73e088c43b5
      partition: 1

Anything else we need to know?:
The CSI translation library makes the partition number available in volume_attribute: partition: https://github.com/kubernetes/kubernetes/blob/bbb58fa085ccfc4635aa8544686d960115449d95/staging/src/k8s.io/csi-translation-lib/plugins/aws_ebs.go#L112

[AndyXiangLi]

Hi @jsafrane can you point me to the in-tree driver code that consume this partition field?

[jsafrane]

Most of the code is in getDiskByIDPaths, it's really about getting the right device name. Beware, NVMe and "regular" disks must be handled differently (/dev/nvme0n1 -> /dev/nvme0n1p1, /dev/xvda -> /dev/xvda1).