Re: [PATCH v6 3/6] refs: receive and use the reference storage payload

diff --git a/refs.c b/refs.c
index 77b93d655b..11d028232b 100644
--- a/refs.c
+++ b/refs.c

@@ -3425,3 +3426,40 @@ const char *ref_transaction_error_msg(enum ref_transaction_error err)
 		return "unknown failure";
 	}
 }
+
+void refs_compute_filesystem_location(const char *gitdir, const char *payload,
+				      bool *is_worktree, struct strbuf *refdir,
+				      struct strbuf *ref_common_dir)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	*is_worktree = get_common_dir_noenv(ref_common_dir, gitdir);
+
+	if (!payload) {
+		/*
+		 * We can use the 'gitdir' as the 'refdir' without appending the
+		 * worktree path, as the 'gitdir' here is already the worktree
+		 * path and is different from 'commondir' denoted by 'ref_common_dir'.
+		 */
+		strbuf_addstr(refdir, gitdir);
+		return;
+	}
+
+	if (!is_absolute_path(payload)) {
+		strbuf_addf(&sb, "%s/%s", ref_common_dir->buf, payload);
+		strbuf_realpath(ref_common_dir, sb.buf, 1);
+	} else {
+		strbuf_realpath(ref_common_dir, payload, 1);
+	}
+
+	strbuf_addbuf(refdir, ref_common_dir);
+
+	if (*is_worktree) {
+		const char *wt_id = strrchr(gitdir, '/');
+		if (!wt_id)
+			BUG("worktree path does not contain slash ");