1 files changed, 246 insertions, 235 deletions

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 922e65e0d9..3dce0c2a34 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -229,6 +229,38 @@ static void add_per_worktree_entries_to_dir(struct ref_dir *dir, const char *dir
 	}
 }
 
+static void loose_fill_ref_dir_regular_file(struct files_ref_store *refs,
+					    const char *refname,
+					    struct ref_dir *dir)
+{
+	struct object_id oid;
+	int flag;
+
+	if (!refs_resolve_ref_unsafe(&refs->base, refname, RESOLVE_REF_READING,
+				     &oid, &flag)) {
+		oidclr(&oid);
+		flag |= REF_ISBROKEN;
+	} else if (is_null_oid(&oid)) {
+		/*
+		 * It is so astronomically unlikely
+		 * that null_oid is the OID of an
+		 * actual object that we consider its
+		 * appearance in a loose reference
+		 * file to be repo corruption
+		 * (probably due to a software bug).
+		 */
+		flag |= REF_ISBROKEN;
+	}
+
+	if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+		if (!refname_is_safe(refname))
+			die("loose refname is dangerous: %s", refname);
+		oidclr(&oid);
+		flag |= REF_BAD_NAME | REF_ISBROKEN;
+	}
+	add_entry_to_dir(dir, create_ref_entry(refname, &oid, flag));
+}
+
 /*
  * Read the loose references from the namespace dirname into dir
  * (without recursing).  dirname must end with '/'.  dir must be the
@@ -257,8 +289,6 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
 	strbuf_add(&refname, dirname, dirnamelen);
 
 	while ((de = readdir(d)) != NULL) {
-		struct object_id oid;
-		int flag;
 		unsigned char dtype;
 
 		if (de->d_name[0] == '.')
@@ -274,33 +304,7 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
 					 create_dir_entry(dir->cache, refname.buf,
 							  refname.len));
 		} else if (dtype == DT_REG) {
-			if (!refs_resolve_ref_unsafe(&refs->base,
-						     refname.buf,
-						     RESOLVE_REF_READING,
-						     &oid, &flag)) {
-				oidclr(&oid);
-				flag |= REF_ISBROKEN;
-			} else if (is_null_oid(&oid)) {
-				/*
-				 * It is so astronomically unlikely
-				 * that null_oid is the OID of an
-				 * actual object that we consider its
-				 * appearance in a loose reference
-				 * file to be repo corruption
-				 * (probably due to a software bug).
-				 */
-				flag |= REF_ISBROKEN;
-			}
-
-			if (check_refname_format(refname.buf,
-						 REFNAME_ALLOW_ONELEVEL)) {
-				if (!refname_is_safe(refname.buf))
-					die("loose refname is dangerous: %s", refname.buf);
-				oidclr(&oid);
-				flag |= REF_BAD_NAME | REF_ISBROKEN;
-			}
-			add_entry_to_dir(dir,
-					 create_ref_entry(refname.buf, &oid, flag));
+			loose_fill_ref_dir_regular_file(refs, refname.buf, dir);
 		}
 		strbuf_setlen(&refname, dirnamelen);
 	}
@@ -311,9 +315,59 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
 	add_per_worktree_entries_to_dir(dir, dirname);
 }
 
-static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
+/*
+ * Add pseudorefs to the ref dir by parsing the directory for any files
+ * which follow the pseudoref syntax.
+ */
+static void add_pseudoref_and_head_entries(struct ref_store *ref_store,
+					 struct ref_dir *dir,
+					 const char *dirname)
+{
+	struct files_ref_store *refs =
+		files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
+	struct strbuf path = STRBUF_INIT, refname = STRBUF_INIT;
+	struct dirent *de;
+	size_t dirnamelen;
+	DIR *d;
+
+	files_ref_path(refs, &path, dirname);
+
+	d = opendir(path.buf);
+	if (!d) {
+		strbuf_release(&path);
+		return;
+	}
+
+	strbuf_addstr(&refname, dirname);
+	dirnamelen = refname.len;
+
+	while ((de = readdir(d)) != NULL) {
+		unsigned char dtype;
+
+		if (de->d_name[0] == '.')
+			continue;
+		if (ends_with(de->d_name, ".lock"))
+			continue;
+		strbuf_addstr(&refname, de->d_name);
+
+		dtype = get_dtype(de, &path, 1);
+		if (dtype == DT_REG && (is_pseudoref(ref_store, de->d_name) ||
+								is_headref(ref_store, de->d_name)))
+			loose_fill_ref_dir_regular_file(refs, refname.buf, dir);
+
+		strbuf_setlen(&refname, dirnamelen);
+	}
+	strbuf_release(&refname);
+	strbuf_release(&path);
+	closedir(d);
+}
+
+static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs,
+					     unsigned int flags)
 {
 	if (!refs->loose) {
+		struct ref_dir *dir;
+
 		/*
 		 * Mark the top-level directory complete because we
 		 * are about to read the only subdirectory that can
@@ -324,12 +378,17 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
 		/* We're going to fill the top level ourselves: */
 		refs->loose->root->flag &= ~REF_INCOMPLETE;
 
+		dir = get_ref_dir(refs->loose->root);
+
+		if (flags & DO_FOR_EACH_INCLUDE_ROOT_REFS)
+			add_pseudoref_and_head_entries(dir->cache->ref_store, dir,
+						       refs->loose->root->name);
+
 		/*
 		 * Add an incomplete entry for "refs/" (to be filled
 		 * lazily):
 		 */
-		add_entry_to_dir(get_ref_dir(refs->loose->root),
-				 create_dir_entry(refs->loose, "refs/", 5));
+		add_entry_to_dir(dir, create_dir_entry(refs->loose, "refs/", 5));
 	}
 	return refs->loose;
 }
@@ -735,8 +794,10 @@ retry:
 		 */
 		if (refs_verify_refname_available(
 				    refs->packed_ref_store, refname,
-				    extras, NULL, err))
+				    extras, NULL, err)) {
+			ret = TRANSACTION_NAME_CONFLICT;
 			goto error_return;
+		}
 	}
 
 	ret = 0;
@@ -857,7 +918,7 @@ static struct ref_iterator *files_ref_iterator_begin(
 	 * disk, and re-reads it if not.
 	 */
 
-	loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
+	loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs, flags),
 					      prefix, ref_store->repo, 1);
 
 	/*
@@ -879,8 +940,7 @@ static struct ref_iterator *files_ref_iterator_begin(
 
 	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
-	base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
-			       overlay_iter->ordered);
+	base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
 	iter->iter0 = overlay_iter;
 	iter->repo = ref_store->repo;
 	iter->flags = flags;
@@ -1140,7 +1200,7 @@ static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
 	ref_transaction_add_update(
 			transaction, r->name,
 			REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,
-			null_oid(), &r->oid, NULL);
+			null_oid(), &r->oid, NULL, NULL, NULL);
 	if (ref_transaction_commit(transaction, &err))
 		goto cleanup;
 
@@ -1218,7 +1278,7 @@ static int files_pack_refs(struct ref_store *ref_store,
 
 	packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
 
-	iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL,
+	iter = cache_ref_iterator_begin(get_loose_ref_cache(refs, 0), NULL,
 					the_repository, 0);
 	while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
 		/*
@@ -1234,7 +1294,7 @@ static int files_pack_refs(struct ref_store *ref_store,
 		 * packed-refs transaction:
 		 */
 		if (ref_transaction_update(transaction, iter->refname,
-					   iter->oid, NULL,
+					   iter->oid, NULL, NULL, NULL,
 					   REF_NO_DEREF, NULL, &err))
 			die("failure preparing to create packed reference %s: %s",
 			    iter->refname, err.buf);
@@ -1263,54 +1323,6 @@ static int files_pack_refs(struct ref_store *ref_store,
 	return 0;
 }
 
-static int files_delete_refs(struct ref_store *ref_store, const char *msg,
-			     struct string_list *refnames, unsigned int flags)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
-	struct strbuf err = STRBUF_INIT;
-	int i, result = 0;
-
-	if (!refnames->nr)
-		return 0;
-
-	if (packed_refs_lock(refs->packed_ref_store, 0, &err))
-		goto error;
-
-	if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
-		packed_refs_unlock(refs->packed_ref_store);
-		goto error;
-	}
-
-	packed_refs_unlock(refs->packed_ref_store);
-
-	for (i = 0; i < refnames->nr; i++) {
-		const char *refname = refnames->items[i].string;
-
-		if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
-			result |= error(_("could not remove reference %s"), refname);
-	}
-
-	strbuf_release(&err);
-	return result;
-
-error:
-	/*
-	 * If we failed to rewrite the packed-refs file, then it is
-	 * unsafe to try to remove loose refs, because doing so might
-	 * expose an obsolete packed value for a reference that might
-	 * even point at an object that has been garbage collected.
-	 */
-	if (refnames->nr == 1)
-		error(_("could not delete reference %s: %s"),
-		      refnames->items[0].string, err.buf);
-	else
-		error(_("could not delete references: %s"), err.buf);
-
-	strbuf_release(&err);
-	return -1;
-}
-
 /*
  * People using contrib's git-new-workdir have .git/logs/refs ->
  * /some/other/path/.git/logs/refs, and that may live on another device.
@@ -1893,66 +1905,23 @@ static int create_ref_symlink(struct ref_lock *lock, const char *target)
 	return ret;
 }
 
-static void update_symref_reflog(struct files_ref_store *refs,
-				 struct ref_lock *lock, const char *refname,
-				 const char *target, const char *logmsg)
-{
-	struct strbuf err = STRBUF_INIT;
-	struct object_id new_oid;
-
-	if (logmsg &&
-	    refs_resolve_ref_unsafe(&refs->base, target,
-				    RESOLVE_REF_READING, &new_oid, NULL) &&
-	    files_log_ref_write(refs, refname, &lock->old_oid,
-				&new_oid, logmsg, 0, &err)) {
-		error("%s", err.buf);
-		strbuf_release(&err);
-	}
-}
-
-static int create_symref_locked(struct files_ref_store *refs,
-				struct ref_lock *lock, const char *refname,
-				const char *target, const char *logmsg)
+static int create_symref_lock(struct files_ref_store *refs,
+			      struct ref_lock *lock, const char *refname,
+			      const char *target, struct strbuf *err)
 {
-	if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
-		update_symref_reflog(refs, lock, refname, target, logmsg);
-		return 0;
+	if (!fdopen_lock_file(&lock->lk, "w")) {
+		strbuf_addf(err, "unable to fdopen %s: %s",
+			     get_lock_file_path(&lock->lk), strerror(errno));
+		return -1;
 	}
 
-	if (!fdopen_lock_file(&lock->lk, "w"))
-		return error("unable to fdopen %s: %s",
+	if (fprintf(get_lock_file_fp(&lock->lk), "ref: %s\n", target) < 0) {
+		strbuf_addf(err, "unable to write to %s: %s",
 			     get_lock_file_path(&lock->lk), strerror(errno));
-
-	update_symref_reflog(refs, lock, refname, target, logmsg);
-
-	/* no error check; commit_ref will check ferror */
-	fprintf(get_lock_file_fp(&lock->lk), "ref: %s\n", target);
-	if (commit_ref(lock) < 0)
-		return error("unable to write symref for %s: %s", refname,
-			     strerror(errno));
-	return 0;
-}
-
-static int files_create_symref(struct ref_store *ref_store,
-			       const char *refname, const char *target,
-			       const char *logmsg)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
-	struct strbuf err = STRBUF_INIT;
-	struct ref_lock *lock;
-	int ret;
-
-	lock = lock_ref_oid_basic(refs, refname, &err);
-	if (!lock) {
-		error("%s", err.buf);
-		strbuf_release(&err);
 		return -1;
 	}
 
-	ret = create_symref_locked(refs, lock, refname, target, logmsg);
-	unlock_ref(lock);
-	return ret;
+	return 0;
 }
 
 static int files_reflog_exists(struct ref_store *ref_store,
@@ -2164,10 +2133,8 @@ static int files_for_each_reflog_ent(struct ref_store *ref_store,
 
 struct files_reflog_iterator {
 	struct ref_iterator base;
-
 	struct ref_store *ref_store;
 	struct dir_iterator *dir_iterator;
-	struct object_id oid;
 };
 
 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
@@ -2178,25 +2145,13 @@ static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
 	int ok;
 
 	while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
-		int flags;
-
 		if (!S_ISREG(diter->st.st_mode))
 			continue;
-		if (diter->basename[0] == '.')
-			continue;
-		if (ends_with(diter->basename, ".lock"))
+		if (check_refname_format(diter->basename,
+					 REFNAME_ALLOW_ONELEVEL))
 			continue;
 
-		if (!refs_resolve_ref_unsafe(iter->ref_store,
-					     diter->relative_path, 0,
-					     &iter->oid, &flags)) {
-			error("bad ref for %s", diter->path.buf);
-			continue;
-		}
-
 		iter->base.refname = diter->relative_path;
-		iter->base.oid = &iter->oid;
-		iter->base.flags = flags;
 		return ITER_OK;
 	}
 
@@ -2241,7 +2196,7 @@ static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
 
 	strbuf_addf(&sb, "%s/logs", gitdir);
 
-	diter = dir_iterator_begin(sb.buf, 0);
+	diter = dir_iterator_begin(sb.buf, DIR_ITERATOR_SORTED);
 	if (!diter) {
 		strbuf_release(&sb);
 		return empty_ref_iterator_begin();
@@ -2250,7 +2205,7 @@ static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
 	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 
-	base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
+	base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
 	iter->dir_iterator = diter;
 	iter->ref_store = ref_store;
 	strbuf_release(&sb);
@@ -2258,32 +2213,6 @@ static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
 	return ref_iterator;
 }
 
-static enum iterator_selection reflog_iterator_select(
-	struct ref_iterator *iter_worktree,
-	struct ref_iterator *iter_common,
-	void *cb_data UNUSED)
-{
-	if (iter_worktree) {
-		/*
-		 * We're a bit loose here. We probably should ignore
-		 * common refs if they are accidentally added as
-		 * per-worktree refs.
-		 */
-		return ITER_SELECT_0;
-	} else if (iter_common) {
-		if (parse_worktree_ref(iter_common->refname, NULL, NULL,
-				       NULL) == REF_WORKTREE_SHARED)
-			return ITER_SELECT_1;
-
-		/*
-		 * The main ref store may contain main worktree's
-		 * per-worktree refs, which should be ignored
-		 */
-		return ITER_SKIP_1;
-	} else
-		return ITER_DONE;
-}
-
 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
 {
 	struct files_ref_store *refs =
@@ -2294,9 +2223,9 @@ static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_st
 		return reflog_iterator_begin(ref_store, refs->gitcommondir);
 	} else {
 		return merge_ref_iterator_begin(
-			0, reflog_iterator_begin(ref_store, refs->base.gitdir),
+			reflog_iterator_begin(ref_store, refs->base.gitdir),
 			reflog_iterator_begin(ref_store, refs->gitcommondir),
-			reflog_iterator_select, refs);
+			ref_iterator_select, refs);
 	}
 }
 
@@ -2339,7 +2268,7 @@ static int split_head_update(struct ref_update *update,
 			transaction, "HEAD",
 			update->flags | REF_LOG_ONLY | REF_NO_DEREF,
 			&update->new_oid, &update->old_oid,
-			update->msg);
+			NULL, NULL, update->msg);
 
 	/*
 	 * Add "HEAD". This insertion is O(N) in the transaction
@@ -2401,8 +2330,9 @@ static int split_symref_update(struct ref_update *update,
 
 	new_update = ref_transaction_add_update(
 			transaction, referent, new_flags,
-			&update->new_oid, &update->old_oid,
-			update->msg);
+			update->new_target ? NULL : &update->new_oid,
+			update->old_target ? NULL : &update->old_oid,
+			update->new_target, update->old_target, update->msg);
 
 	new_update->parent_update = update;
 
@@ -2431,17 +2361,6 @@ static int split_symref_update(struct ref_update *update,
 }
 
 /*
- * Return the refname under which update was originally requested.
- */
-static const char *original_update_refname(struct ref_update *update)
-{
-	while (update->parent_update)
-		update = update->parent_update;
-
-	return update->refname;
-}
-
-/*
  * Check whether the REF_HAVE_OLD and old_oid values stored in update
  * are consistent with oid, which is the reference's current value. If
  * everything is OK, return 0; otherwise, write an error message to
@@ -2457,16 +2376,16 @@ static int check_old_oid(struct ref_update *update, struct object_id *oid,
 	if (is_null_oid(&update->old_oid))
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference already exists",
-			    original_update_refname(update));
+			    ref_update_original_update_refname(update));
 	else if (is_null_oid(oid))
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference is missing but expected %s",
-			    original_update_refname(update),
+			    ref_update_original_update_refname(update),
 			    oid_to_hex(&update->old_oid));
 	else
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "is at %s but expected %s",
-			    original_update_refname(update),
+			    ref_update_original_update_refname(update),
 			    oid_to_hex(oid),
 			    oid_to_hex(&update->old_oid));
 
@@ -2501,7 +2420,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 
 	files_assert_main_repository(refs, "lock_ref_for_update");
 
-	if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
+	if ((update->flags & REF_HAVE_NEW) && ref_update_has_null_new_value(update))
 		update->flags |= REF_DELETING;
 
 	if (head_ref) {
@@ -2520,7 +2439,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 
 		reason = strbuf_detach(err, NULL);
 		strbuf_addf(err, "cannot lock ref '%s': %s",
-			    original_update_refname(update), reason);
+			    ref_update_original_update_refname(update), reason);
 		free(reason);
 		goto out;
 	}
@@ -2540,11 +2459,18 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 				if (update->flags & REF_HAVE_OLD) {
 					strbuf_addf(err, "cannot lock ref '%s': "
 						    "error reading reference",
-						    original_update_refname(update));
+						    ref_update_original_update_refname(update));
 					ret = TRANSACTION_GENERIC_ERROR;
 					goto out;
 				}
-			} else if (check_old_oid(update, &lock->old_oid, err)) {
+			}
+
+			if (update->old_target) {
+				if (ref_update_check_old_target(referent.buf, update, err)) {
+					ret = TRANSACTION_GENERIC_ERROR;
+					goto out;
+				}
+			} else if  (check_old_oid(update, &lock->old_oid, err)) {
 				ret = TRANSACTION_GENERIC_ERROR;
 				goto out;
 			}
@@ -2565,7 +2491,17 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 	} else {
 		struct ref_update *parent_update;
 
-		if (check_old_oid(update, &lock->old_oid, err)) {
+		/*
+		 * Even if the ref is a regular ref, if `old_target` is set, we
+		 * check the referent value. Ideally `old_target` should only
+		 * be set for symrefs, but we're strict about its usage.
+		 */
+		if (update->old_target) {
+			if (ref_update_check_old_target(referent.buf, update, err)) {
+				ret = TRANSACTION_GENERIC_ERROR;
+				goto out;
+			}
+		} else if  (check_old_oid(update, &lock->old_oid, err)) {
 			ret = TRANSACTION_GENERIC_ERROR;
 			goto out;
 		}
@@ -2583,9 +2519,28 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 		}
 	}
 
-	if ((update->flags & REF_HAVE_NEW) &&
-	    !(update->flags & REF_DELETING) &&
-	    !(update->flags & REF_LOG_ONLY)) {
+	if (update->new_target && !(update->flags & REF_LOG_ONLY)) {
+		if (create_symref_lock(refs, lock, update->refname,
+				       update->new_target, err)) {
+			ret = TRANSACTION_GENERIC_ERROR;
+			goto out;
+		}
+
+		if (close_ref_gently(lock)) {
+			strbuf_addf(err, "couldn't close '%s.lock'",
+				    update->refname);
+			ret = TRANSACTION_GENERIC_ERROR;
+			goto out;
+		}
+
+		/*
+		 * Once we have created the symref lock, the commit
+		 * phase of the transaction only needs to commit the lock.
+		 */
+		update->flags |= REF_NEEDS_COMMIT;
+	} else if ((update->flags & REF_HAVE_NEW) &&
+		   !(update->flags & REF_DELETING) &&
+		   !(update->flags & REF_LOG_ONLY)) {
 		if (!(update->type & REF_ISSYMREF) &&
 		    oideq(&lock->old_oid, &update->new_oid)) {
 			/*
@@ -2793,7 +2748,7 @@ static int files_transaction_prepare(struct ref_store *ref_store,
 					packed_transaction, update->refname,
 					REF_HAVE_NEW | REF_NO_DEREF,
 					&update->new_oid, NULL,
-					NULL);
+					NULL, NULL, NULL);
 		}
 	}
 
@@ -2848,6 +2803,43 @@ cleanup:
 	return ret;
 }
 
+static int parse_and_write_reflog(struct files_ref_store *refs,
+				  struct ref_update *update,
+				  struct ref_lock *lock,
+				  struct strbuf *err)
+{
+	if (update->new_target) {
+		/*
+		 * We want to get the resolved OID for the target, to ensure
+		 * that the correct value is added to the reflog.
+		 */
+		if (!refs_resolve_ref_unsafe(&refs->base, update->new_target,
+					     RESOLVE_REF_READING,
+					     &update->new_oid, NULL)) {
+			/*
+			 * TODO: currently we skip creating reflogs for dangling
+			 * symref updates. It would be nice to capture this as
+			 * zero oid updates however.
+			 */
+			return 0;
+		}
+	}
+
+	if (files_log_ref_write(refs, lock->ref_name, &lock->old_oid,
+				&update->new_oid, update->msg, update->flags, err)) {
+		char *old_msg = strbuf_detach(err, NULL);
+
+		strbuf_addf(err, "cannot update the ref '%s': %s",
+			    lock->ref_name, old_msg);
+		free(old_msg);
+		unlock_ref(lock);
+		update->backend_data = NULL;
+		return -1;
+	}
+
+	return 0;
+}
+
 static int files_transaction_finish(struct ref_store *ref_store,
 				    struct ref_transaction *transaction,
 				    struct strbuf *err)
@@ -2878,23 +2870,20 @@ static int files_transaction_finish(struct ref_store *ref_store,
 
 		if (update->flags & REF_NEEDS_COMMIT ||
 		    update->flags & REF_LOG_ONLY) {
-			if (files_log_ref_write(refs,
-						lock->ref_name,
-						&lock->old_oid,
-						&update->new_oid,
-						update->msg, update->flags,
-						err)) {
-				char *old_msg = strbuf_detach(err, NULL);
-
-				strbuf_addf(err, "cannot update the ref '%s': %s",
-					    lock->ref_name, old_msg);
-				free(old_msg);
-				unlock_ref(lock);
-				update->backend_data = NULL;
+			if (parse_and_write_reflog(refs, update, lock, err)) {
 				ret = TRANSACTION_GENERIC_ERROR;
 				goto cleanup;
 			}
 		}
+
+		/*
+		 * We try creating a symlink, if that succeeds we continue to the
+		 * next update. If not, we try and create a regular symref.
+		 */
+		if (update->new_target && prefer_symlink_refs)
+			if (!create_ref_symlink(lock, update->new_target))
+				continue;
+
 		if (update->flags & REF_NEEDS_COMMIT) {
 			clear_loose_ref_cache(refs);
 			if (commit_ref(lock)) {
@@ -3078,7 +3067,7 @@ static int files_initial_transaction_commit(struct ref_store *ref_store,
 		ref_transaction_add_update(packed_transaction, update->refname,
 					   update->flags & ~REF_HAVE_OLD,
 					   &update->new_oid, &update->old_oid,
-					   NULL);
+					   NULL, NULL, NULL);
 	}
 
 	if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
@@ -3266,28 +3255,52 @@ static int files_reflog_expire(struct ref_store *ref_store,
 	return -1;
 }
 
-static int files_init_db(struct ref_store *ref_store, struct strbuf *err UNUSED)
+static int files_init_db(struct ref_store *ref_store,
+			 int flags,
+			 struct strbuf *err UNUSED)
 {
 	struct files_ref_store *refs =
 		files_downcast(ref_store, REF_STORE_WRITE, "init_db");
 	struct strbuf sb = STRBUF_INIT;
 
 	/*
-	 * Create .git/refs/{heads,tags}
+	 * We need to create a "refs" dir in any case so that older versions of
+	 * Git can tell that this is a repository. This serves two main purposes:
+	 *
+	 * - Clients will know to stop walking the parent-directory chain when
+	 *   detecting the Git repository. Otherwise they may end up detecting
+	 *   a Git repository in a parent directory instead.
+	 *
+	 * - Instead of failing to detect a repository with unknown reference
+	 *   format altogether, old clients will print an error saying that
+	 *   they do not understand the reference format extension.
 	 */
-	files_ref_path(refs, &sb, "refs/heads");
+	strbuf_addf(&sb, "%s/refs", ref_store->gitdir);
 	safe_create_dir(sb.buf, 1);
+	adjust_shared_perm(sb.buf);
 
-	strbuf_reset(&sb);
-	files_ref_path(refs, &sb, "refs/tags");
-	safe_create_dir(sb.buf, 1);
+	/*
+	 * There is no need to create directories for common refs when creating
+	 * a worktree ref store.
+	 */
+	if (!(flags & REFS_INIT_DB_IS_WORKTREE)) {
+		/*
+		 * Create .git/refs/{heads,tags}
+		 */
+		strbuf_reset(&sb);
+		files_ref_path(refs, &sb, "refs/heads");
+		safe_create_dir(sb.buf, 1);
+
+		strbuf_reset(&sb);
+		files_ref_path(refs, &sb, "refs/tags");
+		safe_create_dir(sb.buf, 1);
+	}
 
 	strbuf_release(&sb);
 	return 0;
 }
 
 struct ref_storage_be refs_be_files = {
-	.next = NULL,
 	.name = "files",
 	.init = files_ref_store_create,
 	.init_db = files_init_db,
@@ -3297,8 +3310,6 @@ struct ref_storage_be refs_be_files = {
 	.initial_transaction_commit = files_initial_transaction_commit,
 
 	.pack_refs = files_pack_refs,
-	.create_symref = files_create_symref,
-	.delete_refs = files_delete_refs,
 	.rename_ref = files_rename_ref,
 	.copy_ref = files_copy_ref,