Fix KBOSS backup creation edge case

[JoaoJandre]

Description

If a new incremental backup is created for a stopped VM, that has a delta tree with more than one branch for one of its volumes, and the VM snapshot following the last backup is the current one, a problem occurs during backup creation where the current VM snapshot delta is not rebased to its new parent, causing subsequent backups to fail and the chain to become inconsistent.

This PR fixes this issue.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• Build/CI
• Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Test description

With a stopped VM, the following tests were performed:

Test	Previous result	Result with patch
Take a backup, a VM snapshot, and a new backup	Success and consistent chain	Success and consistent chain
Take a backup, two consecutive VM snapshots, revert to the first VM snapshot, take a new VM snapshot, and then take a new backup	Success and consistent chain	Success and consistent chain
Take a backup, two consecutive VM snapshots, revert to the first VM snapshot, and then take a new backup	Success, but the chain becomes inconsistent, making it impossible to start the VM	Success and consistent chain

[JoaoJandre]

@winterhazel if we have a new RC could we include this?
Otherwise, this can go to the next minor.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 19.65%. Comparing base (dbee809) to head (8a6889d).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../apache/cloudstack/backup/KbossBackupProvider.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main   #13880   +/-   ##
=========================================
  Coverage     19.64%   19.65%           
- Complexity    19784    19795   +11     
=========================================
  Files          6368     6368           
  Lines        574889   574889           
  Branches      70353    70353           
=========================================
+ Hits         112935   112986   +51     
+ Misses       449684   449633   -51     
  Partials      12270    12270           

Flag	Coverage Δ
uitests	3.41% <ø> (ø)
unittests	20.92% <50.00%> (+<0.01%)	⬆️

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[winterhazel]

@winterhazel if we have a new RC could we include this? Otherwise, this can go to the next minor.

@JoaoJandre 4.23 will not have any minor. I will include it in RC3.

[winterhazel]

@blueorangutan package

[weizhouapache]

@blueorangutan package

[blueorangutan]

@weizhouapache a [SL] Jenkins job has been kicked to build packages. It will be bundled with no SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✖️ el8 ✖️ el9 ✖️ debian ✖️ suse15. SL-JID 18882

[JoaoJandre]

@blueorangutan package

[blueorangutan]

@JoaoJandre a [SL] Jenkins job has been kicked to build packages. It will be bundled with no SystemVM templates. I'll keep you posted as I make progress.

[weizhouapache]

code lgtm

[blueorangutan]

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✔️ debian ✔️ suse15. SL-JID 18886