Re: [PATCH v8 06/11] submodule--helper: add gitdir migration command

> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index b3d6f9ff68..271d549bac 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -1266,6 +1266,66 @@ static int module_gitdir(int argc, const char **argv, const char *prefix UNUSED,
>  	return 0;
>  }
>  
> +static int module_migrate(int argc UNUSED, const char **argv UNUSED,
> +			  const char *prefix UNUSED, struct repository *repo)
> +{
> +	struct strbuf module_dir = STRBUF_INIT;
> +	DIR *dir;
> +	struct dirent *de;
> +	int repo_version = 0;
> +
> +	repo_git_path_append(repo, &module_dir, "modules/");
> +
> +	dir = opendir(module_dir.buf);
> +	if (!dir)
> +		die(_("could not open '%s'"), module_dir.buf);
> +
> +	while ((de = readdir(dir))) {
> +		struct strbuf gitdir_path = STRBUF_INIT;
> +		char *key;
> +		const char *value;
> +
> +		if (is_dot_or_dotdot(de->d_name))
> +			continue;
> +
> +		strbuf_addf(&gitdir_path, "%s/%s", module_dir.buf, de->d_name);
> +		if (!is_git_directory(gitdir_path.buf)) {
> +			strbuf_release(&gitdir_path);
> +			continue;
> +		}
> +		strbuf_release(&gitdir_path);
> +
> +		key = xstrfmt("submodule.%s.gitdir", de->d_name);
> +		if (!repo_config_get_string_tmp(repo, key, &value)) {
> +			/* Already has a gitdir config, nothing to do. */
> +			free(key);
> +			continue;
> +		}
> +		free(key);
> +
> +		create_default_gitdir_config(de->d_name);
> +	}
> +
> +	closedir(dir);
> +	strbuf_release(&module_dir);
> +
> +	repo_config_get_int(the_repository, "core.repositoryformatversion", &repo_version);
> +	if (repo_version == 0 &&
> +	    repo_config_set_gently(repo, "core.repositoryformatversion", "1"))
> +		die(_("could not set core.repositoryformatversion to 1. "
> +		      "Please set it for migration to work, for example: "
> +		      "git config core.repositoryformatversion 1"));
> +
> +	if (repo_config_set_gently(repo, "extensions.submodulePathConfig", "true"))
> +		die(_("could not enable submodulePathConfig extension. It is required "
> +		      "for migration to work. Please enable it in the root repo: "
> +		      "git config extensions.submodulePathConfig true"));