S3CSI-224: Reject -o mount option with InvalidArgument error

[anurag4DSB]

Summary

• The CSI driver previously silently stripped the fstab-style -o flag from mountOptions, giving no indication to users that the flag was unsupported. After upgrade, any PV or StorageClass carrying -o would mount without it — silently ignoring user intent.
• This change makes -o an explicit rejection: NodePublishVolume returns an InvalidArgument gRPC error with a clear message, causing the pod event to surface the issue immediately with actionable guidance.
• This is a breaking change: any existing deployment with -o in mountOptions will see pod failures after upgrade. The migration path is simply to remove the -o entries (they were always ignored and had no effect on the mount).

Breaking Change

Any PV or StorageClass that has -o in mountOptions will fail to mount after this upgrade.

Migration: Remove -o entries from mountOptions. If the intent was to pass options like -o uid=1000,allow-other, specify each option as its own entry instead:

# Before (broken after upgrade)
mountOptions:
  - "-o uid=1000,allow-other"

# After
mountOptions:
  - "uid=1000"
  - "allow-other"

Test plan

• Unit test passes: make test
• E2E static provisioning: pod with -o in PV mountOptions fails with not supported in CSI Driver event
• E2E dynamic provisioning: pod with -o in StorageClass mountOptions fails with not supported in CSI Driver event
• Docs render correctly: make docs — verify Troubleshooting and Mount Options pages show new content

Issue: S3CSI-224

[codecov]

❌ 3 Tests Failed:

Tests completed	Failed	Passed	Skipped
133	3	130	58

View the top 3 failed test(s) by shortest run time

Scality CSI Driver for S3 E2E Suite::[It] [sig-storage] CSI Volumes [Driver: s3.csi.scality.com] [Testpattern: Pre-provisioned PV (default fs)] filepermissions should handle mv correctly (metadata intact or ENOTSUP) [sig-storage]

Stack Traces | 8.39s run time

[FAILED] Expected an error to have occurred.  Got:
    <nil>: nil
In [It] at: .../e2e/customsuites/filepermissions.go:1153 @ 03/10/26 17:08:28.492

Scality CSI Driver for S3 E2E Suite::[It] [sig-storage] CSI Volumes [Driver: s3.csi.scality.com] [Testpattern: Dynamic PV (default fs)] dynamic-provisioning-mount-options Mount args policy enforcement in dynamic provisioning should reject -o mount option with InvalidArgument error [sig-storage]

Stack Traces | 130s run time

[FAILED] timed out after 2m0s waiting for error pattern "not supported in CSI Driver" on pod pvc-tester-jn565
In [It] at: .../e2e/customsuites/dynamic_provisioning_mount_options.go:526 @ 03/10/26 17:09:24.684

Scality CSI Driver for S3 E2E Suite::[It] [sig-storage] CSI Volumes [Driver: s3.csi.scality.com] [Testpattern: Pre-provisioned PV (default fs)] mountoptions Mount arg policy enforcement rejects -o flag with InvalidArgument error [sig-storage]

Stack Traces | 130s run time

[FAILED] timed out after 2m0s waiting for error pattern "not supported in CSI Driver" on pod pvc-tester-vk4lh
In [It] at: .../e2e/customsuites/mountoptions.go:277 @ 03/10/26 17:10:53.478

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