6 files changed, 50 insertions, 43 deletions
diff --git a/builtin/grep.c b/builtin/grep.c
index 336cfcab6f..cfcf916bce 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -505,7 +505,8 @@ static int grep_submodule(struct grep_opt *opt,
 	 * lazily registered as alternates when needed (and except in an
 	 * unexpected code interaction, it won't be needed).
 	 */
-	add_submodule_odb_by_path(subrepo->objects->sources->path);
+	odb_add_submodule_source_by_path(the_repository->objects,
+					 subrepo->objects->sources->path);
 	obj_read_unlock();
 
 	memcpy(&subopt, opt, sizeof(subopt));
diff --git a/odb.c b/odb.c
index 4f03be7f77..f0b27bd936 100644
--- a/odb.c
+++ b/odb.c
@@ -24,6 +24,7 @@
 #include "strbuf.h"
 #include "strvec.h"
 #include "submodule.h"
+#include "trace2.h"
 #include "write-or-die.h"
 
 KHASH_INIT(odb_path_map, const char * /* key: odb_path */,
@@ -469,6 +470,12 @@ struct odb_source *odb_find_source(struct object_database *odb, const char *obj_
 	return source;
 }
 
+void odb_add_submodule_source_by_path(struct object_database *odb,
+				      const char *path)
+{
+	string_list_insert(&odb->submodule_source_paths, path);
+}
+
 static void fill_alternate_refs_command(struct child_process *cmd,
 					const char *repo_path)
 {
@@ -623,6 +630,23 @@ void disable_obj_read_lock(void)
 
 int fetch_if_missing = 1;
 
+static int register_all_submodule_sources(struct object_database *odb)
+{
+	int ret = odb->submodule_source_paths.nr;
+
+	for (size_t i = 0; i < odb->submodule_source_paths.nr; i++)
+		odb_add_to_alternates_memory(odb,
+					     odb->submodule_source_paths.items[i].string);
+	if (ret) {
+		string_list_clear(&odb->submodule_source_paths, 0);
+		trace2_data_intmax("submodule", odb->repo,
+				   "register_all_submodule_sources/registered", ret);
+		if (git_env_bool("GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB", 0))
+			BUG("register_all_submodule_sources() called");
+	}
+	return ret;
+}
+
 static int do_oid_object_info_extended(struct repository *r,
 				       const struct object_id *oid,
 				       struct object_info *oi, unsigned flags)
@@ -676,13 +700,12 @@ static int do_oid_object_info_extended(struct repository *r,
 		}
 
 		/*
-		 * If r is the_repository, this might be an attempt at
-		 * accessing a submodule object as if it were in the_repository
-		 * (having called add_submodule_odb() on that submodule's ODB).
-		 * If any such ODBs exist, register them and try again.
+		 * This might be an attempt at accessing a submodule object as
+		 * if it were in main object store (having called
+		 * `odb_add_submodule_source_by_path()` on that submodule's
+		 * ODB). If any such ODBs exist, register them and try again.
 		 */
-		if (r == the_repository &&
-		    register_all_submodule_odb_as_alternates())
+		if (register_all_submodule_sources(r->objects))
 			/* We added some alternates; retry */
 			continue;
 
@@ -968,6 +991,7 @@ struct object_database *odb_new(struct repository *repo)
 	INIT_LIST_HEAD(&o->packed_git_mru);
 	hashmap_init(&o->pack_map, pack_map_entry_cmp, NULL, 0);
 	pthread_mutex_init(&o->replace_mutex, NULL);
+	string_list_init_dup(&o->submodule_source_paths);
 	return o;
 }
 
@@ -1017,4 +1041,5 @@ void odb_clear(struct object_database *o)
 	o->packed_git = NULL;
 
 	hashmap_clear(&o->pack_map);
+	string_list_clear(&o->submodule_source_paths, 0);
 }
diff --git a/odb.h b/odb.h
index 4e2d1004f8..0ea9d4faa7 100644
--- a/odb.h
+++ b/odb.h
@@ -6,6 +6,7 @@
 #include "list.h"
 #include "oidset.h"
 #include "oidmap.h"
+#include "string-list.h"
 #include "thread-utils.h"
 
 struct oidmap;
@@ -165,6 +166,12 @@ struct object_database {
 	 * packs.
 	 */
 	unsigned packed_git_initialized : 1;
+
+	/*
+	 * Submodule source paths that will be added as additional sources to
+	 * allow lookup of submodule objects via the main object database.
+	 */
+	struct string_list submodule_source_paths;
 };
 
 struct object_database *odb_new(struct repository *repo);
@@ -192,6 +199,14 @@ void odb_restore_primary_source(struct object_database *odb,
 				const char *old_path);
 
 /*
+ * Call odb_add_submodule_source_by_path() to add the submodule at the given
+ * path to a list. The object stores of all submodules in that list will be
+ * added as additional sources in the object store when looking up objects.
+ */
+void odb_add_submodule_source_by_path(struct object_database *odb,
+				      const char *path);
+
+/*
  * Iterate through all alternates of the database and execute the provided
  * callback function for each of them. Stop iterating once the callback
  * function returns a non-zero value, in which case the value is bubbled up
diff --git a/submodule-config.c b/submodule-config.c
index 9c80f9f7b6..a9f7210788 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -810,7 +810,8 @@ static void config_from_gitmodules(config_fn_t fn, struct repository *repo, void
 			   repo_get_oid(repo, GITMODULES_HEAD, &oid) >= 0) {
 			config_source.blob = oidstr = xstrdup(oid_to_hex(&oid));
 			if (repo != the_repository)
-				add_submodule_odb_by_path(repo->objects->sources->path);
+				odb_add_submodule_source_by_path(the_repository->objects,
+								 repo->objects->sources->path);
 		} else {
 			goto out;
 		}
diff --git a/submodule.c b/submodule.c
index 386be23423..788c9e55ed 100644
--- a/submodule.c
+++ b/submodule.c
@@ -31,7 +31,6 @@
 #include "commit-reach.h"
 #include "read-cache-ll.h"
 #include "setup.h"
-#include "trace2.h"
 
 static int config_update_recurse_submodules = RECURSE_SUBMODULES_OFF;
 static int initialized_fetch_ref_tips;
@@ -176,31 +175,6 @@ void stage_updated_gitmodules(struct index_state *istate)
 		die(_("staging updated .gitmodules failed"));
 }
 
-static struct string_list added_submodule_odb_paths = STRING_LIST_INIT_DUP;
-
-void add_submodule_odb_by_path(const char *path)
-{
-	string_list_insert(&added_submodule_odb_paths, path);
-}
-
-int register_all_submodule_odb_as_alternates(void)
-{
-	int i;
-	int ret = added_submodule_odb_paths.nr;
-
-	for (i = 0; i < added_submodule_odb_paths.nr; i++)
-		odb_add_to_alternates_memory(the_repository->objects,
-					     added_submodule_odb_paths.items[i].string);
-	if (ret) {
-		string_list_clear(&added_submodule_odb_paths, 0);
-		trace2_data_intmax("submodule", the_repository,
-				   "register_all_submodule_odb_as_alternates/registered", ret);
-		if (git_env_bool("GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB", 0))
-			BUG("register_all_submodule_odb_as_alternates() called");
-	}
-	return ret;
-}
-
 void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
 					     const char *path)
 {
diff --git a/submodule.h b/submodule.h
index db980c1d08..b10e16e6c0 100644
--- a/submodule.h
+++ b/submodule.h
@@ -105,15 +105,6 @@ int submodule_uses_gitfile(const char *path);
 int bad_to_remove_submodule(const char *path, unsigned flags);
 
 /*
- * Call add_submodule_odb_by_path() to add the submodule at the given
- * path to a list. When register_all_submodule_odb_as_alternates() is
- * called, the object stores of all submodules in that list will be
- * added as alternates in the_repository.
- */
-void add_submodule_odb_by_path(const char *path);
-int register_all_submodule_odb_as_alternates(void);
-
-/*
  * Checks if there are submodule changes in a..b. If a is the null OID,
  * checks b and all its ancestors instead.
  */