Re: [PATCH v5 3/4] refs: allow reference location in refstorage config

From: Karthik Nayak <karthik.188@gmail.com>
Date: Feb 10, 2026, 13:02 UTC
Message-ID: <CAOLa=ZRU5Bv6oAUmRkBY-sar2UskPfmJNehUjyMtKJOS4s9S9g@mail.gmail.com>
In-Reply-To: <aYoMk5HmpSyN1azt@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

Show 15 quoted lines

> On Mon, Feb 09, 2026 at 04:58:20PM +0100, Karthik Nayak wrote:
>> The 'extensions.refStorage' config is used to specify the reference
>> backend for a given repository. Both the 'files' and 'reftable' backends
>> utilize the $GIT_DIR as the reference folder by default in
>> `get_main_ref_store()`.
>>
>> Since the reference backends are pluggable, this means that they could
>> work with out-of-tree reference directories too. Extend the 'refStorage'
>> config to also support taking an URI input, where users can specify the
>> reference backend and the location.
>>
>> Add the required changes to obtain and propagate this value to the
>> individual backends also add the necessary documentation and tests.
>
> This reads as if this should have been two sentences.

Yeah, let me split it up.

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>
>> diff --git a/builtin/worktree.c b/builtin/worktree.c
>> index fbdaf2eb2e..94480be5c4 100644
>> --- a/builtin/worktree.c
>> +++ b/builtin/worktree.c
>> @@ -425,6 +425,39 @@ static int make_worktree_orphan(const char * ref, const struct add_opts *opts,
>>  	return run_command(&cp);
>>  }
>>
>> +/*
>> + * References for worktress are generally stored in '$GIT_DIR/worktrees/<wt_id>'.
>
> s/worktress/worktrees/
>

Oops.

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>> +for to_format in $ref_formats
>> +do
>> +	if test "$from_format" = "$to_format"
>> +	then
>> +		continue
>> +	fi
>> +
>> +
>> +	for dir in "$(pwd)/repo/.git" "./"
>
> As "./" is a relative directory I expect it to be resolved relative to
> "$GIT_DIR", right?

Yup the './' is relative to the '$GIT_DIR'. It can be changed to '.', so I'll do that and add a comment. So we do both

  BACKEND_PATH='/home/karthik/code/git/build/test-output/trash
directory.t1423-ref-backend/repo/.git/ref_migration.ZnKNpg'

and

  BACKEND_PATH=./ref_migration.BFyK5k

> Also, I don't see any tests that create the ref
> directory outside of the repository. Should we maybe add one?

Yeah, let me add that test.

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>> +	do
>> +
>> +		test_expect_success "$read from $to_format backend, $dir dir" '
>> +			test_when_finished "rm -rf repo" &&
>> +			git init --ref-format=$from_format repo &&
>> +			(
>> +				cd repo &&
>> +				test_commit 1 &&
>> +				test_commit 2 &&
>> +				test_commit 3 &&
>> +
>> +				git refs migrate --dry-run --ref-format=$to_format >out &&
>
> Okay, we do the migration, but with "--dry-run". This should result in a
> temporary staging directory, which is in fact somewhat interesting given
> that "to_format" can now contain a payload. I assume it wouldn't have an
> impact if such a payload was set here?
>

It cannot, the 'git refs migrate' command parses the argument provided to '--ref-format' as a reference-backend.

>> +				BACKEND_PATH="$dir/$(sed "s/.* ${SQ}.git\/\(.*\)${SQ}/\1/" out)" &&
>
> Hm. I have no idea what this is doing :)
>

It extracts out the name of the dry-run folder created by 'git refs migrate'. We append the $dir to it, which could be the absolute path or the relative path.

Show 13 quoted lines

>> +				test_refs_backend . $from_format "$to_format://$BACKEND_PATH" "$method"
>> +			)
>> +		'
>
> In general I think it would be sensible to also have a couple tests here
> that exercise specific formats directly. Like:
>
>   - Are the files created in the right spots for the files and reftable
>     backend with a specific backend?
>
>   - Does `git refs migrate` know to write the files into the correct
>     location in case "--dry-run" wasn't passed?
>

Will add tests for the following too.

>   - Does git-init(1) and git-clone(1) initialize the refstore in a
>     different location as expected?
>

Well so this only works when there is a reference store already existing. I thought I had explicitly called this out, but doesn't seem to be the case. I think it would actually make sense that it also works with creation. So let me look into that.

>   - Does creating a worktree work?
>

This is currently already tested.

> Patrick