rbd: skip flatten for ROX snapshot restores by Rakshith-R · Pull Request #6534 · ceph/ceph-csi

Rakshith-R · 2026-09-03T11:14:12Z

Summary

Preserve the RBD parent chain when restoring snapshots as read-only volumes. This allows rbd diff changed-block tracking to work for incremental backups.

CreateVolume passes the all-capabilities reader-only state to flattenParentImage. ROX snapshot restores return before flattening, while RW and mixed-capability restores retain the existing flattening behavior.

The clone-depth acceptance coverage now verifies both behaviors with trashed parents: ROX restores retain a parent, and RW restores flatten the image.

Validation

internal/csi-common unit tests
internal/rbd unit tests
go vet for touched packages and e2e
E2E compile check
PR acceptance E2E passed

Assisted-by: Claude Code noreply@anthropic.com

CI resource ordering.

Depends-on: #6490

Copilot

🔵 Needs a closer look

It changes core RBD snapshot-restore behavior in the CSI controller (flattening semantics), which can have broad functional impact and should be validated by a maintainer with real-world upgrade/backup workflows in mind.

Pull request overview

This PR updates the RBD CSI controller snapshot-restore path to preserve deep clone chains for read-only (ROX) restores by skipping parent flattening, enabling tools like rbd diff to leverage the parent chain for incremental backup workflows. It also extends the RBD E2E coverage to assert ROX retention behavior while keeping existing RW restore flattening behavior.

Changes:

Skip flattenParentImage() during CreateVolume when restoring from a snapshot with exclusively reader-only capabilities.
Add AreAllCapabilitiesReaderOnly() helper (with unit tests) to distinguish “all-RO” requests from mixed capability sets.
Extend the “trashed parents + clone depth” RBD E2E to verify ROX restore retains the parent chain and RW restore still triggers flattening (and label it for acceptance).

File summaries

File	Description
internal/rbd/controllerserver.go	Skips snapshot-parent flattening for ROX snapshot restores while preserving existing behavior for RW restores.
internal/csi-common/utils.go	Adds `AreAllCapabilitiesReaderOnly()` to detect exclusively reader-only capability sets.
internal/csi-common/utils_test.go	Adds unit tests for the new `AreAllCapabilitiesReaderOnly()` helper.
e2e/rbd.go	Updates/renames the clone-depth test and adds `acceptance` label.
e2e/rbd_helper.go	Refactors parent-detection logic and adds `ensureRBDImageHasParent()` plus `getRBDImageParent()` helper.
e2e/rbd_clone_depth.go	Extends the trashed-parent clone-depth scenario to cover ROX retention and RW flattening expectations.

Review details

Files reviewed: 6/6 changed files
Comments generated: 1
Review effort level: Lite

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Copilot

🟢 Approval recommended

The focused behavior change is validated by comprehensive unit and end-to-end coverage.

Review details

Files reviewed: 6/6 changed files
Comments generated: 0 new
Review effort level: Balanced

Copilot

🟢 Approval recommended

The implementation is focused, handles malformed capabilities safely, and includes appropriate unit and E2E coverage.

Review details

Files reviewed: 6/6 changed files
Comments generated: 0 new
Review effort level: Balanced

nixpanic · 2026-09-08T11:02:23Z

Wait for #6490 to be merged before adding /queue here.

mergify · 2026-09-08T11:02:42Z

Merge Protections

🟢 All 2 merge protections satisfied — ready to merge.

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🟢 ⛓️ Depends-On Requirements

Requirement based on the presence of Depends-On in the body of the pull request

depends-on = ceph/ceph-csi#6490 [⛓️ rbd, cephfs: return InvalidArgument for undecodable volume IDs in DeleteVolume #6490]

🟢 🚦 Auto-queue

When all merge protections are satisfied, this pull request will be queued automatically.

nixpanic · 2026-09-09T07:22:11Z

/queue

ceph-csi-bot · 2026-09-09T07:22:37Z

@Mergifyio rebase

mergify · 2026-09-09T07:22:47Z

rebase

🛑 The pull request rule doesn't match anymore

Details

This action has been cancelled.

Avoid flattening snapshot parents when restoring read-only volumes so deep clone chains remain intact. Extend the trashed-parent E2E to verify ROX retention and RW flattening. Assisted-by: Claude Code <noreply@anthropic.com> Signed-off-by: Rakshith R <rar@redhat.com>

ceph-csi-bot · 2026-09-09T07:23:16Z

/test ci/centos/upgrade-tests-cephfs

ceph-csi-bot · 2026-09-09T07:23:17Z

/test ci/centos/k8s-e2e-external-storage/1.36

ceph-csi-bot · 2026-09-09T07:23:18Z

/test ci/centos/k8s-e2e-external-storage/1.34

ceph-csi-bot · 2026-09-09T07:23:18Z

/test ci/centos/k8s-e2e-external-storage/1.35

ceph-csi-bot · 2026-09-09T07:23:18Z

/test ci/centos/upgrade-tests-rbd

ceph-csi-bot · 2026-09-09T07:23:18Z

/test ci/centos/mini-e2e-helm/k8s-1.36

ceph-csi-bot · 2026-09-09T07:23:18Z

/test ci/centos/mini-e2e-helm/k8s-1.34

ceph-csi-bot · 2026-09-09T07:23:19Z

/test ci/centos/mini-e2e-helm/k8s-1.35

ceph-csi-bot · 2026-09-09T07:23:19Z

/test ci/centos/mini-e2e/k8s-1.36

ceph-csi-bot · 2026-09-09T07:23:19Z

/test ci/centos/mini-e2e/k8s-1.34

ceph-csi-bot · 2026-09-09T07:23:20Z

/test ci/centos/mini-e2e/k8s-1.35

iPraveenParihar · 2026-09-09T08:04:18Z

/retest ci/centos/mini-e2e/k8s-1.34

mergify · 2026-09-09T12:14:56Z

Deprecation notice: This pull request comes from a fork and was queued with update_method=rebase and update_bot_account impersonation. This capability will be removed on July 1, 2026. After this date, the merge queue will no longer be able to rebase fork pull requests with this configuration. To avoid disruption, switch to update_method=merge in your queue rule.

mergify · 2026-09-09T12:14:58Z

Merge Queue Status

✅ Entered queue — 2026-09-09 12:14 UTC · Rule: default · triggered by merge protections
✅ Checks skipped · PR is already up-to-date
✅ Merged — 2026-09-09 12:15 UTC · at c2be926f46d436f7c8870ef01d3853554544ec81 · rebase

This pull request spent 11 seconds in the queue, including 2 seconds running CI.

Required conditions to merge

depends-on = ceph/ceph-csi#6490 [⛓️ rbd, cephfs: return InvalidArgument for undecodable volume IDs in DeleteVolume #6490]
- rbd: skip flatten for ROX snapshot restores #6534
github-review-approved [🛡 GitHub branch protection]
- rbd: skip flatten for ROX snapshot restores #6534

Copilot AI lite review requested due to automatic review settings September 3, 2026 11:14

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Comment thread e2e/rbd_helper.go

Rakshith-R requested a balanced review from Copilot September 3, 2026 11:21

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Rakshith-R force-pushed the rox-snapshot-skip-flatten branch 2 times, most recently from 917177d to 9e38256 Compare September 7, 2026 10:25

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Rakshith-R force-pushed the rox-snapshot-skip-flatten branch from 9e38256 to 3cd412a Compare September 7, 2026 11:07

Rakshith-R changed the title ~~Rox snapshot skip flatten~~ rbd: skip flatten for ROX snapshot restores Sep 7, 2026

mergify Bot added the component/rbd Issues related to RBD label Sep 7, 2026

Rakshith-R force-pushed the rox-snapshot-skip-flatten branch 2 times, most recently from 3890922 to d1d5bbb Compare September 7, 2026 11:58

Rakshith-R marked this pull request as ready for review September 7, 2026 12:00

Rakshith-R requested review from a team as code owners September 7, 2026 12:00

black-dragon74 reviewed Sep 8, 2026

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Comment thread internal/rbd/controllerserver.go

Rakshith-R force-pushed the rox-snapshot-skip-flatten branch 2 times, most recently from 3c85645 to ad22352 Compare September 8, 2026 09:38

Rakshith-R requested a review from black-dragon74 September 8, 2026 09:39

Rakshith-R force-pushed the rox-snapshot-skip-flatten branch from ad22352 to 3617669 Compare September 8, 2026 09:43

black-dragon74 approved these changes Sep 8, 2026

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iPraveenParihar approved these changes Sep 8, 2026

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Madhu-1 approved these changes Sep 8, 2026

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nixpanic mentioned this pull request Sep 8, 2026

nvmeof: change the return error code #6535

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ceph-csi-bot added the queued/rebase label Sep 9, 2026

ceph-csi-bot force-pushed the rox-snapshot-skip-flatten branch from 3617669 to 144534c Compare September 9, 2026 07:23

ceph-csi-bot added ok-to-test Label to trigger E2E tests and removed queued/rebase labels Sep 9, 2026

ceph-csi-bot added ci/in-progress/e2e This label acts like a guard and prevents Mergify from adding the `ok-to-test` label again. and removed ok-to-test Label to trigger E2E tests labels Sep 9, 2026

mergify Bot removed the ci/in-progress/e2e This label acts like a guard and prevents Mergify from adding the `ok-to-test` label again. label Sep 9, 2026

mergify Bot merged commit c2be926 into ceph:devel Sep 9, 2026
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nixpanic mentioned this pull request Sep 9, 2026

cleanup: use read-only image opens #6536

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Rakshith-R commented Sep 3, 2026 •

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