Re: [PATCH v6 4/6] refs: move out stub modification to generic layer

> When creating the reftable reference backend on disk, we create stubs to
> ensure that the directory can be recognized as a Git repository. This is
> done by calling `refs_create_refdir_stubs()`. Move this to the generic
> layer as this is needed for all backends excluding from the files
> backends. In an upcoming commit, we'll also need to extend this logic to
> create stubs when using alternate reference directories.
> 
> Similarly, move the logic for deletion of stubs to the generic layer.
> The files backend recursively calls the remove function of the
> 'packed-backend', here skip calling the generic function since that
> would try to delete stubs.

> diff --git a/refs.c b/refs.c
> index 11d028232b..a24602c9bf 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -2190,12 +2190,59 @@ void refs_create_refdir_stubs(struct repository *repo, const char *refdir,
>  /* backend functions */
>  int ref_store_create_on_disk(struct ref_store *refs, int flags, struct strbuf *err)
>  {
> -	return refs->be->create_on_disk(refs, flags, err);
> +	int ret = refs->be->create_on_disk(refs, flags, err);
> +
> +	if (!ret &&
> +	    ref_storage_format_by_name(refs->be->name) != REF_STORAGE_FORMAT_FILES) {
> +		struct strbuf msg = STRBUF_INIT;
> +
> +		strbuf_addf(&msg, "this repository uses the %s format", refs->be->name);
> +		refs_create_refdir_stubs(refs->repo, refs->gitdir, msg.buf);
> +		strbuf_release(&msg);
> +	}
> +
> +	return ret;
>  }

>  int ref_store_remove_on_disk(struct ref_store *refs, struct strbuf *err)
>  {
> -	return refs->be->remove_on_disk(refs, err);
> +	int ret = refs->be->remove_on_disk(refs, err);
> +
> +	if (!ret) {
> +		enum ref_storage_format format = ref_storage_format_by_name(refs->be->name);
> +		struct strbuf sb = STRBUF_INIT;
> +
> +		/* Backends apart from the files backend create stubs. */
> +		if (format == REF_STORAGE_FORMAT_FILES)
> +			return ret;