Restore failed from VolumeSnapshot when G unit is specified

[ysakashita]

Describe the bug

If I specify G unit of size in PVC, I get a failure to restore from snapshot.
The reason is that the size requires a larger capacity than the size of the source PV.

$ kubectl describe pvc restore-block 
...
Events:
  Type     Reason                Age                  From                                                                                     Message
  ----     ------                ----                 ----                                                                                     -------
  Normal   Provisioning          9s (x8 over 2m14s)   csi.trident.netapp.io_trident-csi-58f9ffd585-sfmqv_479e54a9-5597-45e0-81ac-23367f8b3edd  External provisioner is provisioning volume for claim "default/restore-block"
  Warning  ProvisioningFailed    9s (x8 over 2m14s)   csi.trident.netapp.io_trident-csi-58f9ffd585-sfmqv_479e54a9-5597-45e0-81ac-23367f8b3edd  failed to provision volume with StorageClass "ontap-block": error getting handle for DataSource Type VolumeSnapshot by Name snap-block-0: requested volume size 10000000000 is less than the size 10001317888 for the source snapshot snap-block-0
  Normal   ExternalProvisioning  5s (x10 over 2m14s)  persistentvolume-controller                                                              waiting for a volume to be created, either by external provisioner "csi.trident.netapp.io" or manually created by system administrator

Environment
Provide accurate information about the environment to help us reproduce the issue.

• Trident version: v20.10.1
• Trident installation flags used: -n trident
• Container runtime: Docker 20.10.2
• Kubernetes version: 1.18.15
• Kubernetes orchestrator: none
• Kubernetes enabled feature gates: none
• OS: Ubuntu 20.04.1
• NetApp backend types: ONTAP AFF 9.5

To Reproduce

1. Create source volume (size 10G)

• mc-test-rw-block.yaml

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mc-test-block
spec:
  serviceName: mc-test-block
  replicas: 1
  selector:
    matchLabels:
      app: mc-test-block
  template:
    metadata:
      labels:
        app: mc-test-block
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - mc-test-block
            topologyKey: "topology.kubernetes.io/zone"
      containers:
      - name: mc-test-block
        image: ubuntu:18.04
        volumeMounts:
        - name: block
          mountPath: /mnt/block
        command: ["/bin/sh"]
        args: ["-c", "while true; do /bin/date >>/mnt/block/time.log; sleep 1; done"]
  volumeClaimTemplates:
  - metadata:
      name: block
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: ontap-block
      resources:
        requests:
          storage: 10G

$ kubectl apply -f mc-test-rw-block.yaml 
statefulset.apps/mc-test-block created

$ kubectl get pod,pvc
NAME                  READY   STATUS    RESTARTS   AGE
pod/mc-test-block-0   1/1     Running   0          30s

NAME                                          STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/block-mc-test-block-0   Bound    pvc-b5512c5d-e180-4ce4-9ab1-e83c8bfc70ea   10Gi       RWO            ontap-block    30s

2. Run VolumeSnapshot

• snapshot-block.yaml

apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
  name: snap-block-0
spec:
  volumeSnapshotClassName: csi-trident-netapp-io
  source:
    persistentVolumeClaimName: block-mc-test-block-0

$ kubectl apply -f snapshot-block.yaml 
volumesnapshot.snapshot.storage.k8s.io/snap-block-0 created

$ kubectl get volumesnapshots.snapshot.storage.k8s.io 
NAME           READYTOUSE   SOURCEPVC               SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS           SNAPSHOTCONTENT                                    CREATIONTIME   AGE
snap-block-0   true         block-mc-test-block-0                           9538Mi        csi-trident-netapp-io   snapcontent-c339fe9f-825f-4f4c-972e-157c42e3ec0b   29s            29s

3. Run Restore

• restore-block.yaml (size 10G : same as the source PV)

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: restore-block
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: ontap-block
  resources:
    requests:
      storage: 10G
  dataSource:
    apiGroup: snapshot.storage.k8s.io
    kind: VolumeSnapshot
    name: snap-block-0
---
apiVersion: v1
kind: Pod
metadata:
  labels:
    run: restore-check-block
  name: restore-check-block
spec:
  containers:
  - image: ubuntu:18.04
    name: restore-check-block
    command:
    - sleep
    - infinity
    volumeMounts:
    - mountPath: /mnt/data
      name: myvolume
  volumes:
  - name: myvolume
    persistentVolumeClaim:
      claimName: restore-block

$ kubectl apply -f restore-block.yaml 
persistentvolumeclaim/restore-block created
pod/restore-check-block created

$ kubectl get pod,pvc
NAME                      READY   STATUS    RESTARTS   AGE
pod/mc-test-block-0       1/1     Running   0          9m31s
pod/restore-check-block   0/1     Pending   0          68s

NAME                                          STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/block-mc-test-block-0   Bound     pvc-b5512c5d-e180-4ce4-9ab1-e83c8bfc70ea   10Gi       RWO            ontap-block    9m31s
persistentvolumeclaim/restore-block           Pending                                                                        ontap-block    68s

$ kubectl describe pvc restore-block 
...
Events:
  Type     Reason                Age                  From                                                                                     Message
  ----     ------                ----                 ----                                                                                     -------
  Normal   Provisioning          9s (x8 over 2m14s)   csi.trident.netapp.io_trident-csi-58f9ffd585-sfmqv_479e54a9-5597-45e0-81ac-23367f8b3edd  External provisioner is provisioning volume for claim "default/restore-block"
  Warning  ProvisioningFailed    9s (x8 over 2m14s)   csi.trident.netapp.io_trident-csi-58f9ffd585-sfmqv_479e54a9-5597-45e0-81ac-23367f8b3edd  failed to provision volume with StorageClass "ontap-block": error getting handle for DataSource Type VolumeSnapshot by Name snap-block-0: requested volume size 10000000000 is less than the size 10001317888 for the source snapshot snap-block-0
  Normal   ExternalProvisioning  5s (x10 over 2m14s)  persistentvolume-controller                                                              waiting for a volume to be created, either by external provisioner "csi.trident.netapp.io" or manually created by system administrator

Expected behavior
I want restore to succeed with the same size specification as Source PV.

Additional context

As far as I have checked, this problem does not occur in Gi units.

[gnarl]

We are currently investigating how to best fix this issue. As mentioned in #617 a user can also experience this error when using G instead of Gi when requesting a PVC clone.

[gnarl]

This issue was fixed with commit 40b3d1b and is included in the Trident v21.07.1 release.