[BUG] persistence.removeSnapshotsDuringFilesystemTrim Helm variable is unreferenced

[ejweber]

Describe the bug

https://github.com/longhorn/longhorn/pull/4919/files added two new Helm variables related to filesystem trim:

• defaultSettings.removeSnapshotsDuringFilesystemTrim is referenced in chart/templates/default-setting.yaml.
• persistence.removeSnapshotsDuringFilesystemTrim should probably be referenced in chart/templates/storageclass.yaml, but actually isn't referenced anywhere.

Expected behavior

Either persistence.removeSnapshotsDuringFilesystemTrim should be referenced or it should be removed.

To be honest, I'm not sure of the value it provides. It makes sense to be able to specify unmapMarkSnapChainRemoved in user-created StorageClasses, since that setting may or may not be desired for different workloads. However, if a user just wants to enable or disable the behavior by default, the default setting should suffice.

[longhorn-io-github-bot]

Pre Ready-For-Testing Checklist

• Where is the reproduce steps/test steps documented?

Default case:

1. Do not set any values.
2. Helm install/upgrade.
3. Check the longhorn StorageClass for unmapMarkSnapChainRemoved: ignored.

Non-default case:

1. Set the value of persistence.removeSnapshotsDuringFilesystemTrim to enabled in `values.yaml.
2. Helm install/upgrade.
3. Check the longhorn StorageClass for unmapMarkSnapChainRemoved: enabled.

• Does the PR include deployment change (YAML/Chart)? If so, where are the PRs for both YAML file and Chart?
  The PR for the YAML change is at: Fix removeSnapshotsDuringFilesystemTrim not being used in helm chart #7911.
  The PR for the chart change is at: Fix removeSnapshotsDuringFilesystemTrim not being used in helm chart #7911.

[ejweber]

Thanks @yardenshoham for the submission. I reviewed and approved the PR, but will need another maintainer to merge it. I'll help shepherd it through the QA and backport process.

[roger-ryao]

Verified on master-head 20240417

• longhorn master-head cb95df3

The test steps

#7909 (comment)

Result Passed

Default case

1. master-head
2. v1.6.1 upgrade to master-head

Non-default case

1. master-head
2. v1.6.1 upgrade to master-head