partitioning: fix #9201 /etc/fstab entry (double comma)

[iav]

Summary

Fixes #9201: double-comma bug in generated /etc/fstab entries (e.g. defaults,,commit=120,errors=remount-ro for ext4).

The root cause: mountopts[] values start with a leading comma by convention (see line 26 comment), but all call sites were adding an explicit comma before the expansion, doubling it.

This is the complete fix suggested by @EvilOlaf in #9227 (#9227 (comment)) — removing the hardcoded , after defaults at all call sites, rather than patching only line 369.

Changes

• Lines 366, 369: root filesystem mount and fstab entry
• Lines 373–386: btrfs subvolume mount and fstab entries (not covered by partitioning: fix malformed fstab double comma and switch to relatime #9227)
• Line 345: btrfs mountopts override was missing the leading comma, accidentally compensated by the extra comma at call sites — fixed to follow the convention

Summary by CodeRabbit

• Refactor
  • Normalized how filesystem mount options are concatenated for Btrfs root and subvolume mounts. Formatting-only change; effective options (e.g., commit settings) and user behavior remain unchanged.

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📝 Walkthrough

Walkthrough

Normalization of mount option concatenation in lib/functions/image/partitioning.sh: adjusted how ${mountopts[$ROOTFS_TYPE]} is concatenated into mount commands and /etc/fstab entries to eliminate spurious commas and preserve intended options (e.g., commit=120) without changing effective option sets.

Changes

Cohort / File(s)	Summary
Partitioning mount-option normalization lib/functions/image/partitioning.sh	Removed explicit per-rootfs-type mountopts assignment and updated concatenation patterns for root and subvolume mounts and corresponding fstab entries (changed -odefaults,${mountopts[...]} → -odefaults${mountopts[...]} and defaults,${mountopts[...]} → defaults${mountopts[...]}) to prevent double commas and normalize formatting.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I nudged a comma out of line,
No more double, systems shine.
Mounts now join as friends, not foes,
fstab sings where chaos froze.
Hoppity, boot bliss—onward it goes.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the specific bug fix (double comma in /etc/fstab) and references the related issue #9201, accurately summarizing the main change.
Linked Issues check	✅ Passed	The pull request successfully addresses all coding requirements from issue #9201: eliminating double commas in /etc/fstab mount options, fixing root filesystem mount option assembly, and ensuring consistency across all affected lines.
Out of Scope Changes check	✅ Passed	All changes in lib/functions/image/partitioning.sh are directly related to fixing the double comma issue in /etc/fstab entries described in issue #9201; no out-of-scope modifications detected.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/9201-fstab-double-comma

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🧹 Nitpick comments (1)

lib/functions/image/partitioning.sh (1)

345-345: Avoid overriding mountopts[btrfs] inside the btrfs block.

Line 345 duplicates the default from Line 85 and can silently override custom mount options set earlier via hooks. Consider removing this reassignment and keeping a single source of truth.

♻️ Proposed cleanup

-			mountopts[$ROOTFS_TYPE]=',commit=120'

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@lib/functions/image/partitioning.sh` at line 345, Inside the btrfs-specific
block you are reassigning mountopts[$ROOTFS_TYPE] to ',commit=120' which
overrides any earlier customizations; remove that reassignment (or change it to
only set a default when mountopts[$ROOTFS_TYPE] is empty, e.g., test -z
"${mountopts[$ROOTFS_TYPE]}" && mountopts[$ROOTFS_TYPE]=',commit=120') so
mountopts[btrfs] remains the single source of truth and hooks can override it.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@lib/functions/image/partitioning.sh`:
- Line 345: Inside the btrfs-specific block you are reassigning
mountopts[$ROOTFS_TYPE] to ',commit=120' which overrides any earlier
customizations; remove that reassignment (or change it to only set a default
when mountopts[$ROOTFS_TYPE] is empty, e.g., test -z
"${mountopts[$ROOTFS_TYPE]}" && mountopts[$ROOTFS_TYPE]=',commit=120') so
mountopts[btrfs] remains the single source of truth and hooks can override it.

---

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📥 Commits

Reviewing files that changed from the base of the PR and between ae08545 and ee8bec9.

📒 Files selected for processing (1)

• lib/functions/image/partitioning.sh

[iav]

rebased

[github-actions]

✅ This PR has been reviewed and approved — all set for merge!