Re: [PATCH] fsck: ignore missing "refs" directory for linked worktrees

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 2, 2025, 01:33 UTC
Message-ID: <xmqqv7pfudux.fsf@gitster.g>
In-Reply-To: <3f731776-9a9e-4c8f-8de9-99d470503345@app.fastmail.com>

"Kristoffer Haugsbakk" <code@khaugsbakk.name> writes:

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> On Sat, May 31, 2025, at 05:39, shejialuo wrote:
>> It is reported that "git refs verify" would fail when encountering
>> worktrees created on Git v2.43.0 or older versions. These versions
>
> Nit: maybe
>
>     "git refs verify" doesn't work if there are worktrees created on Git
>     v2.43.0 ...

Yeah, "It is reported that" was somewhat odd introduction.

>> don't automatically create the "refs" directory, causing the error:
>>
>>     error: cannot open directory .git/worktrees/<worktree name>/refs:
>>     No such file or directory

The original of this part already reads quite well, I think.

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>> Since 8f4c00de95 (builtin/worktree: create refdb via ref backend,
>> 2024-01-08), we automatically create the "refs" directory for new
>> worktrees. However, the fsck code incorrectly assumes all linked
>> worktrees have this directory, thus introducing compatibility issue.
>
> Thanks for finding that commit.

Yup. And that one is v2.44.0-rc0~58^2, and that is where "v2.43" in the above description comes from.

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> At this point in the message it seems like the fsck code never worked
> with these old linked worktrees.  But `git refs verify` used to work
> with them until 7c78d819e6a (ref: support multiple worktrees check for
> refs, 2024-11-20) which was part of v2.48.0.  So I think it’s worth
> mentioning that commit as well.

Good suggestion.

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> Like I said in the first email the only minor regression in this release
> cycle is that git-fsck(1) reports these errors on stderr because the
> default `--reference`.  This was how I spotted the issue on rc0.  But I
> neglected to mention that the commit that introduced `--references`
> (default) for git-fsck(1) is v2.48.0-rc1-49-gc1cf918d3ad (builtin/fsck:
> add `git refs verify` child process, 2025-02-28).[1]

Thanks for a careful analysis. The "fix" is rather obvious, so let's see if we can come up with the final wording of the commit log message and merge it down in time ;-).