diff --git a/builtin/clone.c b/builtin/clone.c
index c990f398ef6f37ef5c7b30941491722f633c54c8..b19b302b06546710b7c8bc20b696a0944c9f1b78 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -1617,7 +1617,7 @@ int cmd_clone(int argc,
 	transport_disconnect(transport);
 
 	if (option_dissociate) {
-		close_object_store(the_repository->objects);
+		odb_close(the_repository->objects);
 		dissociate_from_references();
 	}
 
diff --git a/builtin/gc.c b/builtin/gc.c
index e9a76243aa633d4512c8c47533542eb490991b9d..c0243ed99e6a33bb50ecffa2382436c508cd2e68 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -1063,7 +1063,7 @@ int cmd_gc(int argc,
 	report_garbage = report_pack_garbage;
 	odb_reprepare(the_repository->objects);
 	if (pack_garbage.nr > 0) {
-		close_object_store(the_repository->objects);
+		odb_close(the_repository->objects);
 		clean_pack_garbage();
 	}
 
@@ -1130,8 +1130,10 @@ static int dfs_on_ref(const struct reference *ref, void *cb_data)
 		return 0;
 
 	commit = lookup_commit(the_repository, maybe_peeled);
-	if (!commit)
+	if (!commit || commit->object.flags & SEEN)
 		return 0;
+	commit->object.flags |= SEEN;
+
 	if (repo_parse_commit(the_repository, commit) ||
 	    commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
 		return 0;
@@ -1141,7 +1143,7 @@ static int dfs_on_ref(const struct reference *ref, void *cb_data)
 	if (data->num_not_in_graph >= data->limit)
 		return 1;
 
-	commit_list_append(commit, &stack);
+	commit_list_insert(commit, &stack);
 
 	while (!result && stack) {
 		struct commit_list *parent;
@@ -1162,7 +1164,7 @@ static int dfs_on_ref(const struct reference *ref, void *cb_data)
 				break;
 			}
 
-			commit_list_append(parent->item, &stack);
+			commit_list_insert(parent->item, &stack);
 		}
 	}
 
@@ -1978,7 +1980,7 @@ static void initialize_task_config(struct maintenance_run_opts *opts,
 		strategy = none_strategy;
 		type = MAINTENANCE_TYPE_SCHEDULED;
 	} else {
-		strategy = gc_strategy;
+		strategy = geometric_strategy;
 		type = MAINTENANCE_TYPE_MANUAL;
 	}
 
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 2b78ba7fe4d14a8bcb12165395ff02deeb8c047f..699fe678cd60b0af8b7edf77f2204a064140d94a 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1640,7 +1640,7 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
 	rename_tmp_packfile(&final_index_name, curr_index_name, &index_name,
 			    hash, "idx", 1);
 
-	if (do_fsck_object)
+	if (do_fsck_object && startup_info->have_repository)
 		packfile_store_load_pack(the_repository->objects->packfiles,
 					 final_index_name, 0);
 
@@ -2110,8 +2110,23 @@ int cmd_index_pack(int argc,
 	else
 		close(input_fd);
 
-	if (do_fsck_object && fsck_finish(&fsck_options))
-		die(_("fsck error in pack objects"));
+	if (do_fsck_object) {
+		/*
+		 * We cannot perform queued consistency checks when running
+		 * outside of a repository because those require us to read
+		 * from the object database, which is uninitialized.
+		 *
+		 * TODO: we may eventually set up an in-memory object database,
+		 * which would allow us to perform these queued checks.
+		 */
+		if (!startup_info->have_repository &&
+		    fsck_has_queued_checks(&fsck_options))
+			die(_("cannot perform queued object checks outside "
+			      "of a repository"));
+
+		if (fsck_finish(&fsck_options))
+			die(_("fsck error in pack objects"));
+	}
 
 	free(opts.anomaly);
 	free(objects);
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index e8ee0e73217aae4f3111a5fb273b851b92ca5339..1f0e6fab1f7da047aa06fc5ced2a76b53511dd76 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -34,7 +34,6 @@
 #include "object-file.h"
 #include "object-name.h"
 #include "odb.h"
-#include "path.h"
 #include "protocol.h"
 #include "commit-reach.h"
 #include "server-info.h"
@@ -42,6 +41,7 @@
 #include "trace2.h"
 #include "worktree.h"
 #include "shallow.h"
+#include "setup.h"
 #include "parse-options.h"
 
 static const char * const receive_pack_usage[] = {
diff --git a/builtin/repack.c b/builtin/repack.c
index cfdb4c0920b191de4b6d1d98d263974116acb678..4621eed3e645fef98e6e9f5099575b3a3c25655b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -294,9 +294,10 @@ int cmd_repack(int argc,
 		strvec_push(&cmd.args, "--all");
 		strvec_push(&cmd.args, "--reflog");
 		strvec_push(&cmd.args, "--indexed-objects");
+
+		if (repo_has_promisor_remote(repo))
+			strvec_push(&cmd.args, "--exclude-promisor-objects");
 	}
-	if (repo_has_promisor_remote(repo))
-		strvec_push(&cmd.args, "--exclude-promisor-objects");
 	if (!write_midx) {
 		if (write_bitmaps > 0)
 			strvec_push(&cmd.args, "--write-bitmap-index");
@@ -488,7 +489,7 @@ int cmd_repack(int argc,
 
 	string_list_sort(&names);
 
-	close_object_store(repo->objects);
+	odb_close(repo->objects);
 
 	/*
 	 * Ok we have prepared all new packfiles.
diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
index 97d7c9522f98684c9f749351798839f7935dcee8..25312bb2a528878a03071bddcbc7ced7eb479d0d 100644
--- a/builtin/upload-archive.c
+++ b/builtin/upload-archive.c
@@ -4,8 +4,8 @@
 #define USE_THE_REPOSITORY_VARIABLE
 #include "builtin.h"
 #include "archive.h"
-#include "path.h"
 #include "pkt-line.h"
+#include "setup.h"
 #include "sideband.h"
 #include "run-command.h"
 #include "strvec.h"
diff --git a/builtin/upload-pack.c b/builtin/upload-pack.c
index c2bbc035ab0c91baf5d66cee8bb370ecf1640505..30498fafea3a8b024b5cc8a8d2da7948325ac6c5 100644
--- a/builtin/upload-pack.c
+++ b/builtin/upload-pack.c
@@ -5,11 +5,11 @@
 #include "gettext.h"
 #include "pkt-line.h"
 #include "parse-options.h"
-#include "path.h"
 #include "protocol.h"
 #include "replace-object.h"
 #include "upload-pack.h"
 #include "serve.h"
+#include "setup.h"
 #include "commit.h"
 #include "environment.h"
 
diff --git a/chdir-notify.c b/chdir-notify.c
index 0d7bc0460747b2973f913b746c4b9ef0ba6b9028..f8bfe3cbef9aba4ec66d14c60a363fc58aff0874 100644
--- a/chdir-notify.c
+++ b/chdir-notify.c
@@ -25,6 +25,24 @@ void chdir_notify_register(const char *name,
 	list_add_tail(&e->list, &chdir_notify_entries);
 }
 
+void chdir_notify_unregister(const char *name, chdir_notify_callback cb,
+			     void *data)
+{
+	struct list_head *pos, *p;
+
+	list_for_each_safe(pos, p, &chdir_notify_entries) {
+		struct chdir_notify_entry *e =
+			list_entry(pos, struct chdir_notify_entry, list);
+
+		if (e->cb != cb || e->data != data || !e->name != !name ||
+		    (e->name && strcmp(e->name, name)))
+			continue;
+
+		list_del(pos);
+		free(e);
+	}
+}
+
 static void reparent_cb(const char *name,
 			const char *old_cwd,
 			const char *new_cwd,
diff --git a/chdir-notify.h b/chdir-notify.h
index 366e4c1ee9908c46ac59bcf6fe9668ea44066aef..81eb69d846e45d18b23484c98c292ed5d996552f 100644
--- a/chdir-notify.h
+++ b/chdir-notify.h
@@ -41,6 +41,8 @@ typedef void (*chdir_notify_callback)(const char *name,
 				      const char *new_cwd,
 				      void *data);
 void chdir_notify_register(const char *name, chdir_notify_callback cb, void *data);
+void chdir_notify_unregister(const char *name, chdir_notify_callback cb,
+			     void *data);
 void chdir_notify_reparent(const char *name, char **path);
 
 /*
diff --git a/fsck.c b/fsck.c
index 8e8083e7c6e42ab4356bd67602e61a367b207f79..6651bda8ceb73a7d3d769af2c97228740568ec16 100644
--- a/fsck.c
+++ b/fsck.c
@@ -1379,6 +1379,12 @@ int fsck_finish(struct fsck_options *options)
 	return ret;
 }
 
+bool fsck_has_queued_checks(struct fsck_options *options)
+{
+	return !oidset_equal(&options->gitmodules_found, &options->gitmodules_done) ||
+	       !oidset_equal(&options->gitattributes_found, &options->gitattributes_done);
+}
+
 void fsck_options_clear(struct fsck_options *options)
 {
 	free(options->msg_type);
diff --git a/fsck.h b/fsck.h
index cb6ef32f4f3aaa1ac2ff8a97e38ab9b60b4fadf9..336917c0451aacc74db1534d21f55ded0baeb8be 100644
--- a/fsck.h
+++ b/fsck.h
@@ -248,6 +248,13 @@ int fsck_tag_standalone(const struct object_id *oid, const char *buffer,
  */
 int fsck_finish(struct fsck_options *options);
 
+/*
+ * Check whether there are any checks that have been queued up and that still
+ * need to be run. Returns `false` iff `fsck_finish()` wouldn't perform any
+ * actions, `true` otherwise.
+ */
+bool fsck_has_queued_checks(struct fsck_options *options);
+
 /*
  * Clear the fsck_options struct, freeing any allocated memory.
  */
diff --git a/http-backend.c b/http-backend.c
index 273ed7266fbff1ef37467775c2d4f26a52c11f0b..24f0dc119ab8e661a38804121167b82188054aa2 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -16,6 +16,7 @@
 #include "run-command.h"
 #include "string-list.h"
 #include "url.h"
+#include "setup.h"
 #include "strvec.h"
 #include "packfile.h"
 #include "odb.h"
diff --git a/http-push.c b/http-push.c
index d86ce7711982066c704662f1d55ad8b0a411cbea..60a9b756209071aa434ac42712bd95e3991d05e4 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1725,6 +1725,7 @@ int cmd_main(int argc, const char **argv)
 	int i;
 	int new_refs;
 	struct ref *ref, *local_refs = NULL;
+	const char *gitdir;
 
 	CALLOC_ARRAY(repo, 1);
 
@@ -1787,7 +1788,7 @@ int cmd_main(int argc, const char **argv)
 	if (delete_branch && rs.nr != 1)
 		die("You must specify only one branch name when deleting a remote branch");
 
-	setup_git_directory();
+	gitdir = setup_git_directory();
 
 	memset(remote_dir_exists, -1, 256);
 
@@ -1941,7 +1942,7 @@ int cmd_main(int argc, const char **argv)
 		if (!push_all && !is_null_oid(&ref->old_oid))
 			strvec_pushf(&commit_argv, "^%s",
 				     oid_to_hex(&ref->old_oid));
-		repo_init_revisions(the_repository, &revs, setup_git_directory());
+		repo_init_revisions(the_repository, &revs, gitdir);
 		setup_revisions_from_strvec(&commit_argv, &revs, NULL);
 		revs.edge_hint = 0; /* just in case */
 
diff --git a/midx-write.c b/midx-write.c
index 23e61cb00014282faadf6b5c29636139ad54b082..e3e9be6d03cd6fd20e761eab3c4bd1ff4b4d6583 100644
--- a/midx-write.c
+++ b/midx-write.c
@@ -1458,7 +1458,7 @@ static int write_midx_internal(struct odb_source *source,
 	}
 
 	if (ctx.m || ctx.base_midx)
-		close_object_store(ctx.repo->objects);
+		odb_close(ctx.repo->objects);
 
 	if (commit_lock_file(&lk) < 0)
 		die_errno(_("could not write multi-pack-index"));
diff --git a/odb.c b/odb.c
index 3ec21ef24e16bb6da22b58abfa50553318f98761..8e67afe185eae99a1619680b4d3e7e1b709a2736 100644
--- a/odb.c
+++ b/odb.c
@@ -1,5 +1,6 @@
 #include "git-compat-util.h"
 #include "abspath.h"
+#include "chdir-notify.h"
 #include "commit-graph.h"
 #include "config.h"
 #include "dir.h"
@@ -9,6 +10,7 @@
 #include "khash.h"
 #include "lockfile.h"
 #include "loose.h"
+#include "midx.h"
 #include "object-file-convert.h"
 #include "object-file.h"
 #include "odb.h"
@@ -22,6 +24,7 @@
 #include "strbuf.h"
 #include "strvec.h"
 #include "submodule.h"
+#include "tmp-objdir.h"
 #include "trace2.h"
 #include "write-or-die.h"
 
@@ -141,9 +144,9 @@ static void read_info_alternates(struct object_database *odb,
 				 const char *relative_base,
 				 int depth);
 
-struct odb_source *odb_source_new(struct object_database *odb,
-				  const char *path,
-				  bool local)
+static struct odb_source *odb_source_new(struct object_database *odb,
+					 const char *path,
+					 bool local)
 {
 	struct odb_source *source;
 
@@ -359,7 +362,7 @@ struct odb_source *odb_set_temporary_primary_source(struct object_database *odb,
 	 * Disable ref updates while a temporary odb is active, since
 	 * the objects in the database may roll back.
 	 */
-	source->disable_ref_updates = 1;
+	odb->repo->disable_ref_updates = true;
 	source->will_destroy = will_destroy;
 	source->next = odb->sources;
 	odb->sources = source;
@@ -386,6 +389,7 @@ void odb_restore_primary_source(struct object_database *odb,
 	if (cur_source->next != restore_source)
 		BUG("we expect the old primary object store to be the first alternate");
 
+	odb->repo->disable_ref_updates = false;
 	odb->sources = restore_source;
 	odb_source_free(cur_source);
 }
@@ -1032,18 +1036,79 @@ int odb_write_object_stream(struct object_database *odb,
 	return odb_source_loose_write_stream(odb->sources, stream, len, oid);
 }
 
-struct object_database *odb_new(struct repository *repo)
+static void odb_update_commondir(const char *name UNUSED,
+				 const char *old_cwd,
+				 const char *new_cwd,
+				 void *cb_data)
+{
+	struct object_database *odb = cb_data;
+	struct tmp_objdir *tmp_objdir;
+	struct odb_source *source;
+
+	tmp_objdir = tmp_objdir_unapply_primary_odb();
+
+	/*
+	 * In theory, we only have to do this for the primary object source, as
+	 * alternates' paths are always resolved to an absolute path.
+	 */
+	for (source = odb->sources; source; source = source->next) {
+		char *path;
+
+		if (is_absolute_path(source->path))
+			continue;
+
+		path = reparent_relative_path(old_cwd, new_cwd,
+					      source->path);
+
+		free(source->path);
+		source->path = path;
+	}
+
+	if (tmp_objdir)
+		tmp_objdir_reapply_primary_odb(tmp_objdir, old_cwd, new_cwd);
+}
+
+struct object_database *odb_new(struct repository *repo,
+				const char *primary_source,
+				const char *secondary_sources)
 {
 	struct object_database *o = xmalloc(sizeof(*o));
+	char *to_free = NULL;
 
 	memset(o, 0, sizeof(*o));
 	o->repo = repo;
 	o->packfiles = packfile_store_new(o);
 	pthread_mutex_init(&o->replace_mutex, NULL);
 	string_list_init_dup(&o->submodule_source_paths);
+
+	if (!primary_source)
+		primary_source = to_free = xstrfmt("%s/objects", repo->commondir);
+	o->sources = odb_source_new(o, primary_source, true);
+	o->sources_tail = &o->sources->next;
+	o->alternate_db = xstrdup_or_null(secondary_sources);
+
+	free(to_free);
+
+	chdir_notify_register(NULL, odb_update_commondir, o);
+
 	return o;
 }
 
+void odb_close(struct object_database *o)
+{
+	struct odb_source *source;
+
+	packfile_store_close(o->packfiles);
+
+	for (source = o->sources; source; source = source->next) {
+		if (source->midx)
+			close_midx(source->midx);
+		source->midx = NULL;
+	}
+
+	close_commit_graph(o);
+}
+
 static void odb_free_sources(struct object_database *o)
 {
 	while (o->sources) {
@@ -1057,30 +1122,29 @@ static void odb_free_sources(struct object_database *o)
 	o->source_by_path = NULL;
 }
 
-void odb_clear(struct object_database *o)
+void odb_free(struct object_database *o)
 {
-	FREE_AND_NULL(o->alternate_db);
+	if (!o)
+		return;
+
+	free(o->alternate_db);
 
 	oidmap_clear(&o->replace_map, 1);
 	pthread_mutex_destroy(&o->replace_mutex);
 
-	free_commit_graph(o->commit_graph);
-	o->commit_graph = NULL;
-	o->commit_graph_attempted = 0;
-
+	odb_close(o);
 	odb_free_sources(o);
-	o->sources_tail = NULL;
-	o->loaded_alternates = 0;
 
 	for (size_t i = 0; i < o->cached_object_nr; i++)
 		free((char *) o->cached_objects[i].value.buf);
-	FREE_AND_NULL(o->cached_objects);
+	free(o->cached_objects);
 
-	close_object_store(o);
 	packfile_store_free(o->packfiles);
-	o->packfiles = NULL;
-
 	string_list_clear(&o->submodule_source_paths, 0);
+
+	chdir_notify_unregister(NULL, odb_update_commondir, o);
+
+	free(o);
 }
 
 void odb_reprepare(struct object_database *o)
diff --git a/odb.h b/odb.h
index 9bb28008b1d953774ee198828298cec364478201..014cd9585a2f6efe7367e300afd465906f4a1e3a 100644
--- a/odb.h
+++ b/odb.h
@@ -66,13 +66,6 @@ struct odb_source {
 	 */
 	bool local;
 
-	/*
-	 * This is a temporary object store created by the tmp_objdir
-	 * facility. Disable ref updates since the objects in the store
-	 * might be discarded on rollback.
-	 */
-	int disable_ref_updates;
-
 	/*
 	 * This object store is ephemeral, so there is no need to fsync.
 	 */
@@ -85,10 +78,6 @@ struct odb_source {
 	char *path;
 };
 
-struct odb_source *odb_source_new(struct object_database *odb,
-				  const char *path,
-				  bool local);
-
 struct packed_git;
 struct packfile_store;
 struct cached_object_entry;
@@ -166,8 +155,30 @@ struct object_database {
 	struct string_list submodule_source_paths;
 };
 
-struct object_database *odb_new(struct repository *repo);
-void odb_clear(struct object_database *o);
+/*
+ * Create a new object database for the given repository.
+ *
+ * If the primary source parameter is set it will override the usual primary
+ * object directory derived from the repository's common directory. The
+ * alternate sources are expected to be a PATH_SEP-separated list of secondary
+ * sources. Note that these alternate sources will be added in addition to, not
+ * instead of, the alternates identified by the primary source.
+ *
+ * Returns the newly created object database.
+ */
+struct object_database *odb_new(struct repository *repo,
+				const char *primary_source,
+				const char *alternate_sources);
+
+/* Free the object database and release all resources. */
+void odb_free(struct object_database *o);
+
+/*
+ * Close the object database and all of its sources so that any held resources
+ * will be released. The database can still be used after closing it, in which
+ * case these resources may be reallocated.
+ */
+void odb_close(struct object_database *o);
 
 /*
  * Clear caches, reload alternates and then reload object sources so that new
diff --git a/oidset.c b/oidset.c
index 8d36aef8dca4fca8aa979692a536687a21f2b90d..c8ff0b385c58acf73c6d1c8bb7f3d658abe16a22 100644
--- a/oidset.c
+++ b/oidset.c
@@ -16,6 +16,22 @@ int oidset_contains(const struct oidset *set, const struct object_id *oid)
 	return pos != kh_end(&set->set);
 }
 
+bool oidset_equal(const struct oidset *a, const struct oidset *b)
+{
+	struct oidset_iter iter;
+	struct object_id *a_oid;
+
+	if (oidset_size(a) != oidset_size(b))
+		return false;
+
+	oidset_iter_init(a, &iter);
+	while ((a_oid = oidset_iter_next(&iter)))
+		if (!oidset_contains(b, a_oid))
+			return false;
+
+	return true;
+}
+
 int oidset_insert(struct oidset *set, const struct object_id *oid)
 {
 	int added;
diff --git a/oidset.h b/oidset.h
index 0106b6f2787f0e4a5feff560554f5bd25748313b..e0f1a6ff4ff20328dff91fdfddafa44990a88f02 100644
--- a/oidset.h
+++ b/oidset.h
@@ -38,6 +38,11 @@ void oidset_init(struct oidset *set, size_t initial_size);
  */
 int oidset_contains(const struct oidset *set, const struct object_id *oid);
 
+/**
+ * Returns true iff `a` and `b` contain the exact same OIDs.
+ */
+bool oidset_equal(const struct oidset *a, const struct oidset *b);
+
 /**
  * Insert the oid into the set; a copy is made, so "oid" does not need
  * to persist after this function is called.
@@ -94,11 +99,11 @@ void oidset_parse_file_carefully(struct oidset *set, const char *path,
 				 oidset_parse_tweak_fn fn, void *cbdata);
 
 struct oidset_iter {
-	kh_oid_set_t *set;
+	const kh_oid_set_t *set;
 	khiter_t iter;
 };
 
-static inline void oidset_iter_init(struct oidset *set,
+static inline void oidset_iter_init(const struct oidset *set,
 				    struct oidset_iter *iter)
 {
 	iter->set = &set->set;
diff --git a/packfile.c b/packfile.c
index 9cc11b6dc56225175cb91268c65f2b034bcd0045..3d8b994a617e81e08b06d5b3b3aaa2999c1f73a0 100644
--- a/packfile.c
+++ b/packfile.c
@@ -443,21 +443,6 @@ void close_pack(struct packed_git *p)
 	oidset_clear(&p->bad_objects);
 }
 
-void close_object_store(struct object_database *o)
-{
-	struct odb_source *source;
-
-	packfile_store_close(o->packfiles);
-
-	for (source = o->sources; source; source = source->next) {
-		if (source->midx)
-			close_midx(source->midx);
-		source->midx = NULL;
-	}
-
-	close_commit_graph(o);
-}
-
 void unlink_pack_path(const char *pack_name, int force_delete)
 {
 	static const char *exts[] = {".idx", ".pack", ".rev", ".keep", ".bitmap", ".promisor", ".mtimes"};
diff --git a/packfile.h b/packfile.h
index 0e178fb279fe93783abb3311dda71027892e09de..20e1cf17b26083c3dd278f188c0ae4ddcd22b7ce 100644
--- a/packfile.h
+++ b/packfile.h
@@ -299,7 +299,6 @@ struct object_database;
 unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, unsigned long *);
 void close_pack_windows(struct packed_git *);
 void close_pack(struct packed_git *);
-void close_object_store(struct object_database *o);
 void unuse_pack(struct pack_window **);
 void clear_delta_base_cache(void);
 struct packed_git *add_packed_git(struct repository *r, const char *path,
diff --git a/path.c b/path.c
index 7f56eaf9930374274042b5af8cfb7219659d1272..d726537622cda67f222229358b8b7edd25c34f1b 100644
--- a/path.c
+++ b/path.c
@@ -738,106 +738,6 @@ char *interpolate_path(const char *path, int real_home)
 	return NULL;
 }
 
-/*
- * First, one directory to try is determined by the following algorithm.
- *
- * (0) If "strict" is given, the path is used as given and no DWIM is
- *     done. Otherwise:
- * (1) "~/path" to mean path under the running user's home directory;
- * (2) "~user/path" to mean path under named user's home directory;
- * (3) "relative/path" to mean cwd relative directory; or
- * (4) "/absolute/path" to mean absolute directory.
- *
- * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
- * in this order. We select the first one that is a valid git repository, and
- * chdir() to it. If none match, or we fail to chdir, we return NULL.
- *
- * If all goes well, we return the directory we used to chdir() (but
- * before ~user is expanded), avoiding getcwd() resolving symbolic
- * links.  User relative paths are also returned as they are given,
- * except DWIM suffixing.
- */
-const char *enter_repo(const char *path, unsigned flags)
-{
-	static struct strbuf validated_path = STRBUF_INIT;
-	static struct strbuf used_path = STRBUF_INIT;
-
-	if (!path)
-		return NULL;
-
-	if (!(flags & ENTER_REPO_STRICT)) {
-		static const char *suffix[] = {
-			"/.git", "", ".git/.git", ".git", NULL,
-		};
-		const char *gitfile;
-		int len = strlen(path);
-		int i;
-		while ((1 < len) && (path[len-1] == '/'))
-			len--;
-
-		/*
-		 * We can handle arbitrary-sized buffers, but this remains as a
-		 * sanity check on untrusted input.
-		 */
-		if (PATH_MAX <= len)
-			return NULL;
-
-		strbuf_reset(&used_path);
-		strbuf_reset(&validated_path);
-		strbuf_add(&used_path, path, len);
-		strbuf_add(&validated_path, path, len);
-
-		if (used_path.buf[0] == '~') {
-			char *newpath = interpolate_path(used_path.buf, 0);
-			if (!newpath)
-				return NULL;
-			strbuf_attach(&used_path, newpath, strlen(newpath),
-				      strlen(newpath));
-		}
-		for (i = 0; suffix[i]; i++) {
-			struct stat st;
-			size_t baselen = used_path.len;
-			strbuf_addstr(&used_path, suffix[i]);
-			if (!stat(used_path.buf, &st) &&
-			    (S_ISREG(st.st_mode) ||
-			    (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
-				strbuf_addstr(&validated_path, suffix[i]);
-				break;
-			}
-			strbuf_setlen(&used_path, baselen);
-		}
-		if (!suffix[i])
-			return NULL;
-		gitfile = read_gitfile(used_path.buf);
-		if (!(flags & ENTER_REPO_ANY_OWNER_OK))
-			die_upon_dubious_ownership(gitfile, NULL, used_path.buf);
-		if (gitfile) {
-			strbuf_reset(&used_path);
-			strbuf_addstr(&used_path, gitfile);
-		}
-		if (chdir(used_path.buf))
-			return NULL;
-		path = validated_path.buf;
-	}
-	else {
-		const char *gitfile = read_gitfile(path);
-		if (!(flags & ENTER_REPO_ANY_OWNER_OK))
-			die_upon_dubious_ownership(gitfile, NULL, path);
-		if (gitfile)
-			path = gitfile;
-		if (chdir(path))
-			return NULL;
-	}
-
-	if (is_git_directory(".")) {
-		set_git_dir(".", 0);
-		check_repository_format(NULL);
-		return path;
-	}
-
-	return NULL;
-}
-
 int calc_shared_perm(struct repository *repo,
 		     int mode)
 {
diff --git a/path.h b/path.h
index e67348f25397cc53bfa24c1908283e6f5420a2c3..0ec95a0b079c905ec82b0f5455b8663827b70db7 100644
--- a/path.h
+++ b/path.h
@@ -146,21 +146,6 @@ int adjust_shared_perm(struct repository *repo, const char *path);
 
 char *interpolate_path(const char *path, int real_home);
 
-/* The bits are as follows:
- *
- * - ENTER_REPO_STRICT: callers that require exact paths (as opposed
- *   to allowing known suffixes like ".git", ".git/.git" to be
- *   omitted) can set this bit.
- *
- * - ENTER_REPO_ANY_OWNER_OK: callers that are willing to run without
- *   ownership check can set this bit.
- */
-enum {
-	ENTER_REPO_STRICT = (1<<0),
-	ENTER_REPO_ANY_OWNER_OK = (1<<1),
-};
-
-const char *enter_repo(const char *path, unsigned flags);
 const char *remove_leading_path(const char *in, const char *prefix);
 const char *relative_path(const char *in, const char *prefix, struct strbuf *sb);
 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len);
diff --git a/refs.c b/refs.c
index 5583f6e09d7c76c132b91d3211d09d0838180c03..046b695bb20f5491e342f28da92a31219cc085c8 100644
--- a/refs.c
+++ b/refs.c
@@ -2508,7 +2508,7 @@ int ref_transaction_prepare(struct ref_transaction *transaction,
 		break;
 	}
 
-	if (refs->repo->objects->sources->disable_ref_updates) {
+	if (refs->repo->disable_ref_updates) {
 		strbuf_addstr(err,
 			      _("ref updates forbidden inside quarantine environment"));
 		return -1;
diff --git a/repository.c b/repository.c
index 6aaa7ba00869bf6aa0450f3fbdf27590f7439228..863f24411b7bf9ac31ee6b2fde1af1b7848d6099 100644
--- a/repository.c
+++ b/repository.c
@@ -52,7 +52,6 @@ static void set_default_hash_algo(struct repository *repo)
 
 void initialize_repository(struct repository *repo)
 {
-	repo->objects = odb_new(repo);
 	repo->remote_state = remote_state_new();
 	repo->parsed_objects = parsed_object_pool_new(repo);
 	ALLOC_ARRAY(repo->index, 1);
@@ -160,29 +159,19 @@ void repo_set_gitdir(struct repository *repo,
 	 * until after xstrdup(root). Then we can free it.
 	 */
 	char *old_gitdir = repo->gitdir;
-	char *objects_path = NULL;
 
 	repo->gitdir = xstrdup(gitfile ? gitfile : root);
 	free(old_gitdir);
 
 	repo_set_commondir(repo, o->commondir);
-	expand_base_dir(&objects_path, o->object_dir,
-			repo->commondir, "objects");
-
-	if (!repo->objects->sources) {
-		repo->objects->sources = odb_source_new(repo->objects,
-							objects_path, true);
-		repo->objects->sources_tail = &repo->objects->sources->next;
-		free(objects_path);
-	} else {
-		free(repo->objects->sources->path);
-		repo->objects->sources->path = objects_path;
-	}
 
-	repo->objects->sources->disable_ref_updates = o->disable_ref_updates;
+	if (!repo->objects)
+		repo->objects = odb_new(repo, o->object_dir, o->alternate_db);
+	else if (!o->skip_initializing_odb)
+		BUG("cannot reinitialize an already-initialized object directory");
+
+	repo->disable_ref_updates = o->disable_ref_updates;
 
-	free(repo->objects->alternate_db);
-	repo->objects->alternate_db = xstrdup_or_null(o->alternate_db);
 	expand_base_dir(&repo->graft_file, o->graft_file,
 			repo->commondir, "info/grafts");
 	expand_base_dir(&repo->index_file, o->index_file,
@@ -382,8 +371,8 @@ void repo_clear(struct repository *repo)
 	FREE_AND_NULL(repo->worktree);
 	FREE_AND_NULL(repo->submodule_prefix);
 
-	odb_clear(repo->objects);
-	FREE_AND_NULL(repo->objects);
+	odb_free(repo->objects);
+	repo->objects = NULL;
 
 	parsed_object_pool_clear(repo->parsed_objects);
 	FREE_AND_NULL(repo->parsed_objects);
diff --git a/repository.h b/repository.h
index 5808a5d610846a0e42233f66e56dcbcebbd3ecd0..6063c4b846d031d657827f8b16d65af8c09e5b29 100644
--- a/repository.h
+++ b/repository.h
@@ -71,6 +71,13 @@ struct repository {
 	 */
 	struct ref_store *refs_private;
 
+	/*
+	 * Disable ref updates. This is especially used in contexts where
+	 * transactions may still be rolled back so that we don't start to
+	 * reference objects that may vanish.
+	 */
+	bool disable_ref_updates;
+
 	/*
 	 * A strmap of ref_stores, stored by submodule name, accessible via
 	 * `repo_get_submodule_ref_store()`.
@@ -187,7 +194,8 @@ struct set_gitdir_args {
 	const char *graft_file;
 	const char *index_file;
 	const char *alternate_db;
-	int disable_ref_updates;
+	bool disable_ref_updates;
+	bool skip_initializing_odb;
 };
 
 void repo_set_gitdir(struct repository *repo, const char *root,
diff --git a/run-command.c b/run-command.c
index ed9575bd6a8cbbab0f25b92e09cf9c2752498523..438a290d30744d88dfc2548c8d74cf8fd7435a4f 100644
--- a/run-command.c
+++ b/run-command.c
@@ -743,7 +743,7 @@ int start_command(struct child_process *cmd)
 	fflush(NULL);
 
 	if (cmd->close_object_store)
-		close_object_store(the_repository->objects);
+		odb_close(the_repository->objects);
 
 #ifndef GIT_WINDOWS_NATIVE
 {
@@ -1828,7 +1828,7 @@ int prepare_auto_maintenance(int quiet, struct child_process *maint)
 	 */
 	if (repo_config_get_bool(the_repository, "maintenance.autodetach", &auto_detach) &&
 	    repo_config_get_bool(the_repository, "gc.autodetach", &auto_detach))
-		auto_detach = 1;
+		auto_detach = git_env_bool("GIT_TEST_MAINT_AUTO_DETACH", true);
 
 	maint->git_cmd = 1;
 	maint->close_object_store = 1;
diff --git a/scalar.c b/scalar.c
index f7543116272b773f7f54f4a4638dd78a5a6f9e3e..2aeb191cc89b729c55b7a748e1d67ae8b23b72a3 100644
--- a/scalar.c
+++ b/scalar.c
@@ -931,7 +931,7 @@ static int cmd_delete(int argc, const char **argv)
 	if (dir_inside_of(cwd, enlistment.buf) >= 0)
 		res = error(_("refusing to delete current working directory"));
 	else {
-		close_object_store(the_repository->objects);
+		odb_close(the_repository->objects);
 		res = delete_enlistment(&enlistment);
 	}
 	strbuf_release(&enlistment);
diff --git a/setup.c b/setup.c
index 7086741e6c2d1f5c73e484b76e1a1272f7d0697d..ae66188af3f6f4bc16c5736a298389e932afe5ac 100644
--- a/setup.c
+++ b/setup.c
@@ -22,7 +22,6 @@
 #include "chdir-notify.h"
 #include "path.h"
 #include "quote.h"
-#include "tmp-objdir.h"
 #include "trace.h"
 #include "trace2.h"
 #include "worktree.h"
@@ -1002,6 +1001,83 @@ const char *read_gitfile_gently(const char *path, int *return_error_code)
 	return error_code ? NULL : path;
 }
 
+static void setup_git_env_internal(const char *git_dir,
+				   bool skip_initializing_odb)
+{
+	char *git_replace_ref_base;
+	const char *shallow_file;
+	const char *replace_ref_base;
+	struct set_gitdir_args args = { NULL };
+	struct strvec to_free = STRVEC_INIT;
+
+	args.commondir = getenv_safe(&to_free, GIT_COMMON_DIR_ENVIRONMENT);
+	args.object_dir = getenv_safe(&to_free, DB_ENVIRONMENT);
+	args.graft_file = getenv_safe(&to_free, GRAFT_ENVIRONMENT);
+	args.index_file = getenv_safe(&to_free, INDEX_ENVIRONMENT);
+	args.alternate_db = getenv_safe(&to_free, ALTERNATE_DB_ENVIRONMENT);
+	if (getenv(GIT_QUARANTINE_ENVIRONMENT))
+		args.disable_ref_updates = true;
+	args.skip_initializing_odb = skip_initializing_odb;
+
+	repo_set_gitdir(the_repository, git_dir, &args);
+	strvec_clear(&to_free);
+
+	if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
+		disable_replace_refs();
+	replace_ref_base = getenv(GIT_REPLACE_REF_BASE_ENVIRONMENT);
+	git_replace_ref_base = xstrdup(replace_ref_base ? replace_ref_base
+							  : "refs/replace/");
+	update_ref_namespace(NAMESPACE_REPLACE, git_replace_ref_base);
+
+	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
+	if (shallow_file)
+		set_alternate_shallow_file(the_repository, shallow_file, 0);
+
+	if (git_env_bool(NO_LAZY_FETCH_ENVIRONMENT, 0))
+		fetch_if_missing = 0;
+}
+
+void setup_git_env(const char *git_dir)
+{
+	setup_git_env_internal(git_dir, false);
+}
+
+static void set_git_dir_1(const char *path, bool skip_initializing_odb)
+{
+	xsetenv(GIT_DIR_ENVIRONMENT, path, 1);
+	setup_git_env_internal(path, skip_initializing_odb);
+}
+
+static void update_relative_gitdir(const char *name UNUSED,
+				   const char *old_cwd,
+				   const char *new_cwd,
+				   void *data UNUSED)
+{
+	char *path = reparent_relative_path(old_cwd, new_cwd,
+					    repo_get_git_dir(the_repository));
+	trace_printf_key(&trace_setup_key,
+			 "setup: move $GIT_DIR to '%s'",
+			 path);
+	set_git_dir_1(path, true);
+	free(path);
+}
+
+static void set_git_dir(const char *path, int make_realpath)
+{
+	struct strbuf realpath = STRBUF_INIT;
+
+	if (make_realpath) {
+		strbuf_realpath(&realpath, path, 1);
+		path = realpath.buf;
+	}
+
+	set_git_dir_1(path, false);
+	if (!is_absolute_path(path))
+		chdir_notify_register(NULL, update_relative_gitdir, NULL);
+
+	strbuf_release(&realpath);
+}
+
 static const char *setup_explicit_git_dir(const char *gitdirenv,
 					  struct strbuf *cwd,
 					  struct repository_format *repo_fmt,
@@ -1628,79 +1704,85 @@ enum discovery_result discover_git_directory_reason(struct strbuf *commondir,
 	return result;
 }
 
-void setup_git_env(const char *git_dir)
-{
-	char *git_replace_ref_base;
-	const char *shallow_file;
-	const char *replace_ref_base;
-	struct set_gitdir_args args = { NULL };
-	struct strvec to_free = STRVEC_INIT;
-
-	args.commondir = getenv_safe(&to_free, GIT_COMMON_DIR_ENVIRONMENT);
-	args.object_dir = getenv_safe(&to_free, DB_ENVIRONMENT);
-	args.graft_file = getenv_safe(&to_free, GRAFT_ENVIRONMENT);
-	args.index_file = getenv_safe(&to_free, INDEX_ENVIRONMENT);
-	args.alternate_db = getenv_safe(&to_free, ALTERNATE_DB_ENVIRONMENT);
-	if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
-		args.disable_ref_updates = 1;
-	}
-
-	repo_set_gitdir(the_repository, git_dir, &args);
-	strvec_clear(&to_free);
-
-	if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
-		disable_replace_refs();
-	replace_ref_base = getenv(GIT_REPLACE_REF_BASE_ENVIRONMENT);
-	git_replace_ref_base = xstrdup(replace_ref_base ? replace_ref_base
-							  : "refs/replace/");
-	update_ref_namespace(NAMESPACE_REPLACE, git_replace_ref_base);
-
-	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
-	if (shallow_file)
-		set_alternate_shallow_file(the_repository, shallow_file, 0);
-
-	if (git_env_bool(NO_LAZY_FETCH_ENVIRONMENT, 0))
-		fetch_if_missing = 0;
-}
-
-static void set_git_dir_1(const char *path)
+const char *enter_repo(const char *path, unsigned flags)
 {
-	xsetenv(GIT_DIR_ENVIRONMENT, path, 1);
-	setup_git_env(path);
-}
+	static struct strbuf validated_path = STRBUF_INIT;
+	static struct strbuf used_path = STRBUF_INIT;
 
-static void update_relative_gitdir(const char *name UNUSED,
-				   const char *old_cwd,
-				   const char *new_cwd,
-				   void *data UNUSED)
-{
-	char *path = reparent_relative_path(old_cwd, new_cwd,
-					    repo_get_git_dir(the_repository));
-	struct tmp_objdir *tmp_objdir = tmp_objdir_unapply_primary_odb();
+	if (!path)
+		return NULL;
 
-	trace_printf_key(&trace_setup_key,
-			 "setup: move $GIT_DIR to '%s'",
-			 path);
-	set_git_dir_1(path);
-	if (tmp_objdir)
-		tmp_objdir_reapply_primary_odb(tmp_objdir, old_cwd, new_cwd);
-	free(path);
-}
+	if (!(flags & ENTER_REPO_STRICT)) {
+		static const char *suffix[] = {
+			"/.git", "", ".git/.git", ".git", NULL,
+		};
+		const char *gitfile;
+		int len = strlen(path);
+		int i;
+		while ((1 < len) && (path[len-1] == '/'))
+			len--;
 
-void set_git_dir(const char *path, int make_realpath)
-{
-	struct strbuf realpath = STRBUF_INIT;
+		/*
+		 * We can handle arbitrary-sized buffers, but this remains as a
+		 * sanity check on untrusted input.
+		 */
+		if (PATH_MAX <= len)
+			return NULL;
 
-	if (make_realpath) {
-		strbuf_realpath(&realpath, path, 1);
-		path = realpath.buf;
+		strbuf_reset(&used_path);
+		strbuf_reset(&validated_path);
+		strbuf_add(&used_path, path, len);
+		strbuf_add(&validated_path, path, len);
+
+		if (used_path.buf[0] == '~') {
+			char *newpath = interpolate_path(used_path.buf, 0);
+			if (!newpath)
+				return NULL;
+			strbuf_attach(&used_path, newpath, strlen(newpath),
+				      strlen(newpath));
+		}
+		for (i = 0; suffix[i]; i++) {
+			struct stat st;
+			size_t baselen = used_path.len;
+			strbuf_addstr(&used_path, suffix[i]);
+			if (!stat(used_path.buf, &st) &&
+			    (S_ISREG(st.st_mode) ||
+			    (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
+				strbuf_addstr(&validated_path, suffix[i]);
+				break;
+			}
+			strbuf_setlen(&used_path, baselen);
+		}
+		if (!suffix[i])
+			return NULL;
+		gitfile = read_gitfile(used_path.buf);
+		if (!(flags & ENTER_REPO_ANY_OWNER_OK))
+			die_upon_dubious_ownership(gitfile, NULL, used_path.buf);
+		if (gitfile) {
+			strbuf_reset(&used_path);
+			strbuf_addstr(&used_path, gitfile);
+		}
+		if (chdir(used_path.buf))
+			return NULL;
+		path = validated_path.buf;
+	}
+	else {
+		const char *gitfile = read_gitfile(path);
+		if (!(flags & ENTER_REPO_ANY_OWNER_OK))
+			die_upon_dubious_ownership(gitfile, NULL, path);
+		if (gitfile)
+			path = gitfile;
+		if (chdir(path))
+			return NULL;
 	}
 
-	set_git_dir_1(path);
-	if (!is_absolute_path(path))
-		chdir_notify_register(NULL, update_relative_gitdir, NULL);
+	if (is_git_directory(".")) {
+		set_git_dir(".", 0);
+		check_repository_format(NULL);
+		return path;
+	}
 
-	strbuf_release(&realpath);
+	return NULL;
 }
 
 static int git_work_tree_initialized;
diff --git a/setup.h b/setup.h
index 8522fa8575da7123d0a9dc57dbabf08677a58eaa..d55dcc66086308b31d86f28bcbb84f5d01e4453f 100644
--- a/setup.h
+++ b/setup.h
@@ -94,9 +94,46 @@ static inline int discover_git_directory(struct strbuf *commondir,
 	return 0;
 }
 
-void set_git_dir(const char *path, int make_realpath);
 void set_git_work_tree(const char *tree);
 
+/* Flags that can be passed to `enter_repo()`. */
+enum {
+	/*
+	 * Callers that require exact paths (as opposed to allowing known
+	 * suffixes like ".git", ".git/.git" to be omitted) can set this bit.
+	 */
+	ENTER_REPO_STRICT = (1<<0),
+
+	/*
+	 * Callers that are willing to run without ownership check can set this
+	 * bit.
+	 */
+	ENTER_REPO_ANY_OWNER_OK = (1<<1),
+};
+
+/*
+ * Discover and enter a repository.
+ *
+ * First, one directory to try is determined by the following algorithm.
+ *
+ * (0) If "strict" is given, the path is used as given and no DWIM is
+ *     done. Otherwise:
+ * (1) "~/path" to mean path under the running user's home directory;
+ * (2) "~user/path" to mean path under named user's home directory;
+ * (3) "relative/path" to mean cwd relative directory; or
+ * (4) "/absolute/path" to mean absolute directory.
+ *
+ * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
+ * in this order. We select the first one that is a valid git repository, and
+ * chdir() to it. If none match, or we fail to chdir, we return NULL.
+ *
+ * If all goes well, we return the directory we used to chdir() (but
+ * before ~user is expanded), avoiding getcwd() resolving symbolic
+ * links.  User relative paths are also returned as they are given,
+ * except DWIM suffixing.
+ */
+const char *enter_repo(const char *path, unsigned flags);
+
 const char *setup_git_directory_gently(int *);
 const char *setup_git_directory(void);
 char *prefix_path(const char *prefix, int len, const char *path);
diff --git a/t/helper/test-repository.c b/t/helper/test-repository.c
index 63c37de33d22f195bb15298527e013e98c778776..9ba94cdffa4c474ee9994198f8641df7975ece15 100644
--- a/t/helper/test-repository.c
+++ b/t/helper/test-repository.c
@@ -17,10 +17,6 @@ static void test_parse_commit_in_graph(const char *gitdir, const char *worktree,
 	struct commit *c;
 	struct commit_list *parent;
 
-	setup_git_env(gitdir);
-
-	repo_clear(the_repository);
-
 	if (repo_init(&r, gitdir, worktree))
 		die("Couldn't init repo");
 
@@ -47,10 +43,6 @@ static void test_get_commit_tree_in_graph(const char *gitdir,
 	struct commit *c;
 	struct tree *tree;
 
-	setup_git_env(gitdir);
-
-	repo_clear(the_repository);
-
 	if (repo_init(&r, gitdir, worktree))
 		die("Couldn't init repo");
 
@@ -75,24 +67,20 @@ static void test_get_commit_tree_in_graph(const char *gitdir,
 
 int cmd__repository(int argc, const char **argv)
 {
-	int nongit_ok = 0;
-
-	setup_git_directory_gently(&nongit_ok);
-
 	if (argc < 2)
 		die("must have at least 2 arguments");
 	if (!strcmp(argv[1], "parse_commit_in_graph")) {
 		struct object_id oid;
 		if (argc < 5)
 			die("not enough arguments");
-		if (parse_oid_hex(argv[4], &oid, &argv[4]))
+		if (parse_oid_hex_any(argv[4], &oid, &argv[4]) == GIT_HASH_UNKNOWN)
 			die("cannot parse oid '%s'", argv[4]);
 		test_parse_commit_in_graph(argv[2], argv[3], &oid);
 	} else if (!strcmp(argv[1], "get_commit_tree_in_graph")) {
 		struct object_id oid;
 		if (argc < 5)
 			die("not enough arguments");
-		if (parse_oid_hex(argv[4], &oid, &argv[4]))
+		if (parse_oid_hex_any(argv[4], &oid, &argv[4]) == GIT_HASH_UNKNOWN)
 			die("cannot parse oid '%s'", argv[4]);
 		test_get_commit_tree_in_graph(argv[2], argv[3], &oid);
 	} else {
diff --git a/t/t0081-find-pack.sh b/t/t0081-find-pack.sh
index 5a628bf7356445384ff97f5e55a8d233379bdecb..26f017422d7253c52e2148ed9eaf8f2f1d6b9717 100755
--- a/t/t0081-find-pack.sh
+++ b/t/t0081-find-pack.sh
@@ -68,6 +68,7 @@ test_expect_success 'add more packfiles' '
 '
 
 test_expect_success 'add more commits (as loose objects)' '
+	test_config maintenance.auto false &&
 	test_commit six &&
 	test_commit seven &&
 
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index e778dd8ae4a6dc5dd91c5f138fd3dd5020364e61..5e4623f7f17fe9a251ab0bf3d135ec1b8ff8a92d 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -31,6 +31,8 @@ Initial setup:
 . "$TEST_DIRECTORY"/lib-rebase.sh
 
 test_expect_success 'setup' '
+	git config set gc.reflogExpire never &&
+	git config set gc.reflogExpireUnreachable never &&
 	git switch -C primary &&
 	test_commit A file1 &&
 	test_commit B file1 &&
diff --git a/t/t3406-rebase-message.sh b/t/t3406-rebase-message.sh
index a1d7fa7f7c6965f49cc017303aca52a658211b10..f89209c8d947b4338d62e329371ce292701c5bd0 100755
--- a/t/t3406-rebase-message.sh
+++ b/t/t3406-rebase-message.sh
@@ -8,6 +8,9 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 . ./test-lib.sh
 
 test_expect_success 'setup' '
+	git config set gc.reflogExpire never &&
+	git config set gc.reflogExpireUnreachable never &&
+
 	test_commit O fileO &&
 	test_commit X fileX &&
 	git branch fast-forward &&
diff --git a/t/t3431-rebase-fork-point.sh b/t/t3431-rebase-fork-point.sh
index be09fc78c16aab1fe525daeaa1348a9db5cec9a6..3a3c3a70a5cf09dc9a723159893806a0f78c24e9 100755
--- a/t/t3431-rebase-fork-point.sh
+++ b/t/t3431-rebase-fork-point.sh
@@ -17,6 +17,8 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 # C was formerly part of main but main was rewound to remove C
 #
 test_expect_success setup '
+	git config set gc.reflogExpire never &&
+	git config set gc.reflogExpireUnreachable never &&
 	test_commit A &&
 	test_commit B &&
 	test_commit C &&
diff --git a/t/t3432-rebase-fast-forward.sh b/t/t3432-rebase-fast-forward.sh
index 5086e14c02207184bd7c048ee2bc2419ad4d1b34..6e8de6c7aa52d1fbf6ca0936d479956d529a09eb 100755
--- a/t/t3432-rebase-fast-forward.sh
+++ b/t/t3432-rebase-fast-forward.sh
@@ -11,6 +11,8 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 . ./test-lib.sh
 
 test_expect_success setup '
+	git config set gc.reflogExpire never &&
+	git config set gc.reflogExpireUnreachable never &&
 	test_commit A &&
 	test_commit B &&
 	test_commit C &&
diff --git a/t/t5302-pack-index.sh b/t/t5302-pack-index.sh
index 413c99274c8f3029cf259ca60c70c31348da12b8..9697448cb276341b11d3541334aae4b88c668997 100755
--- a/t/t5302-pack-index.sh
+++ b/t/t5302-pack-index.sh
@@ -293,4 +293,20 @@ test_expect_success 'too-large packs report the breach' '
 	grep "maximum allowed size (20 bytes)" err
 '
 
+# git-index-pack(1) uses the default hash algorithm outside of the repository,
+# and it has no way to tell it otherwise. So we can only run this test with the
+# default hash algorithm, as it would otherwise fail to parse the tree.
+test_expect_success DEFAULT_HASH_ALGORITHM 'index-pack --fsck-objects outside of a repo' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		printf "100644 blob $(test_oid 001)\t.gitattributes\n" >tree &&
+		git mktree --missing <tree >tree-oid &&
+		git pack-objects <tree-oid pack &&
+		test_must_fail nongit git index-pack --fsck-objects "$(pwd)"/pack-*.pack 2>err &&
+		test_grep "cannot perform queued object checks outside of a repository" err
+	)
+'
+
 test_done
diff --git a/t/t5316-pack-delta-depth.sh b/t/t5316-pack-delta-depth.sh
index 03dfb7a61ea978dc7358ba1a8c703b860a23fdf6..8a067a45cb4baebc4f70d197242878fe036202d3 100755
--- a/t/t5316-pack-delta-depth.sh
+++ b/t/t5316-pack-delta-depth.sh
@@ -48,6 +48,7 @@ test_description='pack-objects breaks long cross-pack delta chains'
 # repeatedly-modified file to generate the delta chain).
 
 test_expect_success 'create series of packs' '
+	test_config maintenance.auto false &&
 	test-tool genrandom foo 4096 >content &&
 	prev= &&
 	for i in $(test_seq 1 10)
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 93f319a4b29fbb3d3899a1d1f3914dd7766dd672..9505dd7defa39c9cbb8c33b4ba1db0f7f1d64b9a 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -1254,11 +1254,13 @@ test_expect_success 'bitmapped packs are stored via the BTMP chunk' '
 	(
 		cd repo &&
 
+		git config set maintenance.auto false &&
 		for i in 1 2 3 4 5
 		do
 			test_commit "$i" &&
 			git repack -d || return 1
 		done &&
+		git config unset maintenance.auto &&
 
 		find $objdir/pack -type f -name "*.idx" | xargs -n 1 basename |
 		sort >packs &&
diff --git a/t/t5326-multi-pack-bitmaps.sh b/t/t5326-multi-pack-bitmaps.sh
index 892aeb09e4b9d710acc625b27ab8eb277b0b690f..62bd973d92afc9393abbb3440caedf38468dfea8 100755
--- a/t/t5326-multi-pack-bitmaps.sh
+++ b/t/t5326-multi-pack-bitmaps.sh
@@ -93,7 +93,8 @@ test_midx_bitmap_cases () {
 	test_expect_success 'setup test_repository' '
 		rm -rf * .git &&
 		git init &&
-		git config pack.writeBitmapLookupTable '"$writeLookupTable"'
+		git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
+		git config maintenance.auto false
 	'
 
 	midx_bitmap_core
diff --git a/t/t5327-multi-pack-bitmaps-rev.sh b/t/t5327-multi-pack-bitmaps-rev.sh
index 9cac03a94bf4b4014d0ecd9fd7fc6320949b3e9f..cfa12de2a8a7baad7f4bf1623b2f948f23b53672 100755
--- a/t/t5327-multi-pack-bitmaps-rev.sh
+++ b/t/t5327-multi-pack-bitmaps-rev.sh
@@ -30,7 +30,8 @@ test_midx_bitmap_rev () {
 	test_expect_success 'setup bitmap config' '
 		rm -rf * .git &&
 		git init &&
-		git config pack.writeBitmapLookupTable '"$writeLookupTable"'
+		git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
+		git config maintenance.auto false
 	'
 
 	midx_bitmap_core rev
diff --git a/t/t5331-pack-objects-stdin.sh b/t/t5331-pack-objects-stdin.sh
index 4a8df5a389d29fb4dbff9ad30d6cd0f2204cf117..8a6bf3d98fbfa487489700bb526bc4a93b4e1273 100755
--- a/t/t5331-pack-objects-stdin.sh
+++ b/t/t5331-pack-objects-stdin.sh
@@ -14,6 +14,7 @@ packed_objects () {
 
 test_expect_success 'setup for --stdin-packs tests' '
 	git init stdin-packs &&
+	git -C stdin-packs config set maintenance.auto false &&
 	(
 		cd stdin-packs &&
 
@@ -255,6 +256,7 @@ test_expect_success '--stdin-packs=follow walks into unknown packs' '
 	git init repo &&
 	(
 		cd repo &&
+		git config set maintenance.auto false &&
 
 		for c in A B C D
 		do
diff --git a/t/t5332-multi-pack-reuse.sh b/t/t5332-multi-pack-reuse.sh
index 395d09444ced72d219ba5f19ae7e3b729aef5590..881ce668e1d14e17be043d208580fa35f1e1f1e0 100755
--- a/t/t5332-multi-pack-reuse.sh
+++ b/t/t5332-multi-pack-reuse.sh
@@ -59,6 +59,7 @@ test_pack_objects_reused () {
 
 test_expect_success 'preferred pack is reused for single-pack reuse' '
 	test_config pack.allowPackReuse single &&
+	git config set maintenance.auto false &&
 
 	for i in A B
 	do
diff --git a/t/t5334-incremental-multi-pack-index.sh b/t/t5334-incremental-multi-pack-index.sh
index d30d7253d6f6ccff503775c2961a4cc983197530..99c7d44d8e9d342c077fab13e5bee2f98a473190 100755
--- a/t/t5334-incremental-multi-pack-index.sh
+++ b/t/t5334-incremental-multi-pack-index.sh
@@ -15,6 +15,7 @@ midx_chain=$midxdir/multi-pack-index-chain
 
 test_expect_success 'convert non-incremental MIDX to incremental' '
 	test_commit base &&
+	git config set maintenance.auto false &&
 	git repack -ad &&
 	git multi-pack-index write &&
 
diff --git a/t/t5400-send-pack.sh b/t/t5400-send-pack.sh
index 83b42ff073397120257eb79096c7162e52990f78..b32a0a6aa77e12b51639a2f04fcdaf49bb8b1203 100755
--- a/t/t5400-send-pack.sh
+++ b/t/t5400-send-pack.sh
@@ -187,6 +187,7 @@ test_expect_success 'receive-pack runs auto-gc in remote repo' '
 		cd child &&
 		git config gc.autopacklimit 1 &&
 		git config gc.autodetach false &&
+		git config maintenance.strategy gc &&
 		git branch test_auto_gc &&
 		# And create a file that follows the temporary object naming
 		# convention for the auto-gc to remove
diff --git a/t/t5500-fetch-pack.sh b/t/t5500-fetch-pack.sh
index 2677cd5faa8253131a7b36cb08c20e6f223099e6..0ddbd7aa9651eccceb95a1c326228c24fa1a889c 100755
--- a/t/t5500-fetch-pack.sh
+++ b/t/t5500-fetch-pack.sh
@@ -154,7 +154,8 @@ test_expect_success 'clone shallow depth 1 with fsck' '
 '
 
 test_expect_success 'clone shallow' '
-	git clone --no-single-branch --depth 2 "file://$(pwd)/." shallow
+	git clone --no-single-branch --depth 2 "file://$(pwd)/." shallow &&
+	git -C shallow config set maintenance.auto false
 '
 
 test_expect_success 'clone shallow depth count' '
diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
index b7059cccaacce0d1f1a7abe8d3adc36499a92fb2..e59307449f1e5882b1ce8064881c212ef5392bb6 100755
--- a/t/t5510-fetch.sh
+++ b/t/t5510-fetch.sh
@@ -1321,6 +1321,7 @@ test_expect_success 'fetching with auto-gc does not lock up' '
 		git config fetch.unpackLimit 1 &&
 		git config gc.autoPackLimit 1 &&
 		git config gc.autoDetach false &&
+		git config maintenance.strategy gc &&
 		GIT_ASK_YESNO="$TRASH_DIRECTORY/askyesno" git fetch --verbose >fetch.out 2>&1 &&
 		test_grep "Auto packing the repository" fetch.out &&
 		! grep "Should I try again" fetch.out
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index 1e354e057fa12ce354c8146bd3920b380d97a08e..1c2805accac63691d0e18919e71cf29037b9cb0c 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -229,7 +229,7 @@ test_expect_success 'fetch --refetch triggers repacking' '
 
 	GIT_TRACE2_EVENT="$PWD/trace1.event" \
 	git -C pc1 fetch --refetch origin &&
-	test_subcommand git maintenance run --auto --no-quiet --detach <trace1.event &&
+	test_subcommand git maintenance run --auto --no-quiet --no-detach <trace1.event &&
 	grep \"param\":\"gc.autopacklimit\",\"value\":\"1\" trace1.event &&
 	grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"-1\" trace1.event &&
 
@@ -238,7 +238,7 @@ test_expect_success 'fetch --refetch triggers repacking' '
 		-c gc.autoPackLimit=0 \
 		-c maintenance.incremental-repack.auto=1234 \
 		-C pc1 fetch --refetch origin &&
-	test_subcommand git maintenance run --auto --no-quiet --detach <trace2.event &&
+	test_subcommand git maintenance run --auto --no-quiet --no-detach <trace2.event &&
 	grep \"param\":\"gc.autopacklimit\",\"value\":\"0\" trace2.event &&
 	grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"-1\" trace2.event &&
 
@@ -247,7 +247,7 @@ test_expect_success 'fetch --refetch triggers repacking' '
 		-c gc.autoPackLimit=1234 \
 		-c maintenance.incremental-repack.auto=0 \
 		-C pc1 fetch --refetch origin &&
-	test_subcommand git maintenance run --auto --no-quiet --detach <trace3.event &&
+	test_subcommand git maintenance run --auto --no-quiet --no-detach <trace3.event &&
 	grep \"param\":\"gc.autopacklimit\",\"value\":\"1\" trace3.event &&
 	grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"0\" trace3.event
 '
@@ -585,6 +585,7 @@ test_expect_success 'verify fetch downloads only one pack when updating refs' '
 	git clone --filter=blob:none "file://$(pwd)/srv.bare" pack-test &&
 	ls pack-test/.git/objects/pack/*pack >pack-list &&
 	test_line_count = 2 pack-list &&
+	test_config -C pack-test maintenance.auto false &&
 	for i in A B C
 	do
 		test_commit -C src $i &&
diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh
index bef472cb8dc37bca8b01874d037e15dfc097c826..ea9aaad47091a40b53e1e09f4e02910fda111529 100755
--- a/t/t6500-gc.sh
+++ b/t/t6500-gc.sh
@@ -11,6 +11,7 @@ test_expect_success 'setup' '
 	# behavior, make sure we always pack everything to one pack by
 	# default
 	git config gc.bigPackThreshold 2g &&
+	git config set --global maintenance.strategy gc &&
 	test_oid_init
 '
 
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 73b78bdd887d80706e2f65dc9c3c25cb81027c71..acc2589f2127275f3fa7993cbceff84419fb36c2 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -217,6 +217,7 @@ test_expect_success 'repack --keep-pack' '
 		cd keep-pack &&
 		# avoid producing different packs due to delta/base choices
 		git config pack.window 0 &&
+		git config maintenance.auto false &&
 		P1=$(commit_and_pack 1) &&
 		P2=$(commit_and_pack 2) &&
 		P3=$(commit_and_pack 3) &&
@@ -260,6 +261,7 @@ test_expect_success 'repacking fails when missing .pack actually means missing o
 
 		# Avoid producing different packs due to delta/base choices
 		git config pack.window 0 &&
+		git config maintenance.auto false &&
 		P1=$(commit_and_pack 1) &&
 		P2=$(commit_and_pack 2) &&
 		P3=$(commit_and_pack 3) &&
@@ -534,6 +536,7 @@ test_expect_success 'setup for --write-midx tests' '
 	(
 		cd midx &&
 		git config core.multiPackIndex true &&
+		git config maintenance.auto false &&
 
 		test_commit base
 	)
diff --git a/t/t7703-repack-geometric.sh b/t/t7703-repack-geometric.sh
index 9fc1626fbfde8989348537903a266eb6cae8600d..6d2c712bffc4b30469ccfe5be1859d1889b861ca 100755
--- a/t/t7703-repack-geometric.sh
+++ b/t/t7703-repack-geometric.sh
@@ -445,4 +445,30 @@ test_expect_success '--geometric -l disables writing bitmaps with non-local pack
 	test_path_is_file member/.git/objects/pack/multi-pack-index-*.bitmap
 '
 
+test_expect_success '--geometric works with promisor packs' '
+	test_when_finished "rm -fr remote local" &&
+
+	git init remote &&
+	test_commit -C remote first file first &&
+	test_commit -C remote second file second &&
+	git -C remote config set uploadpack.allowfilter 1 &&
+	git -C remote config set uploadpack.allowanysha1inwant 1 &&
+	git -C remote repack -Ad &&
+
+	git clone --filter=blob:none file://"$(pwd)"/remote local &&
+	git -C local rev-list --objects --missing=print HEAD >missing-objects &&
+	test_grep "^?" missing-objects &&
+
+	# Assert that promisor packs are left alone and that we still manage to
+	# create new geometric packs.
+	ls local/.git/objects/pack/*.promisor >promisors-before &&
+	ls local/.git/objects/pack/*.pack >packs-before &&
+	test_commit -C local change &&
+	git -C local repack --geometric=2 &&
+	ls local/.git/objects/pack/*.promisor >promisors-after &&
+	ls local/.git/objects/pack/*.pack >packs-after &&
+	! cmp packs-before packs-after &&
+	test_cmp promisors-before promisors-after
+'
+
 test_done
diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
index 6b36f52df7c95df666a9b5281e6281e2b8eb73ab..5726f6c8361c456f04b065d6688ec12ed3e493d4 100755
--- a/t/t7900-maintenance.sh
+++ b/t/t7900-maintenance.sh
@@ -6,6 +6,7 @@ test_description='git maintenance builtin'
 
 GIT_TEST_COMMIT_GRAPH=0
 GIT_TEST_MULTI_PACK_INDEX=0
+sane_unset GIT_TEST_MAINT_AUTO_DETACH
 
 test_lazy_prereq XMLLINT '
 	xmllint --version
@@ -42,7 +43,8 @@ test_expect_success 'help text' '
 	test_grep "usage: git maintenance" err
 '
 
-test_expect_success 'run [--auto|--quiet]' '
+test_expect_success 'run [--auto|--quiet] with gc strategy' '
+	test_config maintenance.strategy gc &&
 	GIT_TRACE2_EVENT="$(pwd)/run-no-auto.txt" \
 		git maintenance run 2>/dev/null &&
 	GIT_TRACE2_EVENT="$(pwd)/run-auto.txt" \
@@ -206,6 +208,32 @@ test_expect_success 'commit-graph auto condition' '
 	test_subcommand $COMMIT_GRAPH_WRITE <cg-two-satisfied.txt
 '
 
+test_expect_success 'commit-graph auto condition with merges' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git config set maintenance.auto false &&
+		git commit --allow-empty -m initial &&
+		git switch --create feature &&
+		git commit --allow-empty -m feature-1 &&
+		git commit --allow-empty -m feature-2 &&
+		git switch - &&
+		git commit --allow-empty -m main-1 &&
+		git commit --allow-empty -m main-2 &&
+		git merge feature &&
+		git branch -D feature &&
+
+		# We have 6 commit, none of which are covered by a commit
+		# graph. So this must be the boundary at which we start to
+		# perform maintenance.
+		test_must_fail git -c maintenance.commit-graph.auto=7 \
+			maintenance is-needed --auto --task=commit-graph &&
+		git -c maintenance.commit-graph.auto=6 \
+			maintenance is-needed --auto --task=commit-graph
+	)
+'
+
 test_expect_success 'run --task=bogus' '
 	test_must_fail git maintenance run --task=bogus 2>err &&
 	test_grep "is not a valid task" err
@@ -471,6 +499,7 @@ test_expect_success 'maintenance.incremental-repack.auto' '
 	(
 		cd incremental-repack-true &&
 		git config core.multiPackIndex true &&
+		git config maintenance.auto false &&
 		run_incremental_repack_and_verify
 	)
 '
@@ -481,6 +510,7 @@ test_expect_success 'maintenance.incremental-repack.auto (when config is unset)'
 	(
 		cd incremental-repack-unset &&
 		test_unconfig core.multiPackIndex &&
+		git config maintenance.auto false &&
 		run_incremental_repack_and_verify
 	)
 '
@@ -591,6 +621,7 @@ test_expect_success 'geometric repacking with --auto' '
 	git init repo &&
 	(
 		cd repo &&
+		git config set maintenance.auto false &&
 
 		# An empty repository does not need repacking, except when
 		# explicitly told to do it.
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 0fb76f7d11e840708d5db521d773b606f2b8bd79..aa805a01ce6035aa1c09894b57abeb86dd47184a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1947,6 +1947,10 @@ test_lazy_prereq COMPAT_HASH '
 GIT_TEST_MAINT_SCHEDULER="none:exit 1"
 export GIT_TEST_MAINT_SCHEDULER
 
+# Ensure that tests cannot race with background maintenance by default.
+GIT_TEST_MAINT_AUTO_DETACH="false"
+export GIT_TEST_MAINT_AUTO_DETACH
+
 # Does this platform support `git fsmonitor--daemon`
 #
 test_lazy_prereq FSMONITOR_DAEMON '