fix: reconstruct the cache for failed replica restarting

[shuo-wu]

Which issue(s) this PR fixes:

Issue longhorn/longhorn#9488

What this PR does / why we need it:

If the upper layer tries to launch a previously failed replica in a newly launched instance manager pod. The pod may have no info then directly treat it as a new replica and skip the cache reconstruction. Finally, this replica will be failed by r.validateAndUpdate() in the next moment.

Special notes for your reviewer:

Additional documentation or context

[coderabbitai]

Walkthrough

The pull request introduces modifications to the Replica struct in the pkg/spdk/replica.go file. The changes focus on refining the logic for replica creation and snapshot management. The Create method now has an improved condition for checking the replica's pending state and reconstruction requirements. The SnapshotCreate method has been enhanced to include error handling for existing snapshots, preventing duplicate snapshot creation.

Changes

File	Change Summary
pkg/spdk/replica.go	- Updated Create method logic for checking replica state and reconstruction conditions - Modified SnapshotCreate method to handle existing snapshots

Assessment against linked issues

Objective	Addressed	Explanation
Support v2 volume delta replica rebuilding [#9488]	❓	Partial implementation visible, but full context of rebuilding not completely clear from the changes

Possibly related PRs

• fix: reconstruct ActiveChain and SnapshotLvolMap while creating replica #284: Modifies Create method in Replica struct, enhancing snapshot management logic
• fix(replica): fix race condition when operating backing image #289: Addresses race conditions in updateHeadCache method of Replica struct

Suggested reviewers

• innobead
• ChanYiLin
• c3y1huang

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

pkg/spdk/replica.go (1)

806-807: Consider adding a log message before or after reconstruction.

This ensures better observability and debugging during replica reuse or restart scenarios. For example, logging both before and after the construct() call can help track the state transitions and potential failures.

     ...
+    r.log.Infof("Attempting to reconstruct failed replica %s", r.Name)
     bdevLvolMap, err := GetBdevLvolMapWithFilter(spdkClient, r.replicaLvolFilter)
     if err != nil {
         return nil, err
     }
     if err := r.construct(bdevLvolMap); err != nil {
         return nil, err
     }
+    r.log.Infof("Successfully reconstructed failed replica %s", r.Name)
     r.State = types.InstanceStateStopped
 ...

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📥 Commits

Reviewing files that changed from the base of the PR and between b3271d0 and 72df024.

📒 Files selected for processing (1)

• pkg/spdk/replica.go (1 hunks)