diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 01a53f3f29..0c68d61b91 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -882,7 +882,8 @@ static void batch_each_object(struct batch_options *opt,
 		struct object_info oi = { 0 };
 
 		for (source = the_repository->objects->sources; source; source = source->next) {
-			int ret = packfile_store_for_each_object(source->files->packed, &oi,
+			struct odb_source_files *files = odb_source_files_downcast(source);
+			int ret = packfile_store_for_each_object(files->packed, &oi,
 								 batch_one_object_oi, &payload, flags);
 			if (ret)
 				break;
diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index 627dcbf4f3..a41f95191e 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -875,6 +875,7 @@ static void end_packfile(void)
 	running = 1;
 	clear_delta_base_cache();
 	if (object_count) {
+		struct odb_source_files *files = odb_source_files_downcast(pack_data->repo->objects->sources);
 		struct packed_git *new_p;
 		struct object_id cur_pack_oid;
 		char *idx_name;
@@ -900,8 +901,7 @@ static void end_packfile(void)
 		idx_name = keep_pack(create_index());
 
 		/* Register the packfile with core git's machinery. */
-		new_p = packfile_store_load_pack(pack_data->repo->objects->sources->files->packed,
-						 idx_name, 1);
+		new_p = packfile_store_load_pack(files->packed, idx_name, 1);
 		if (!new_p)
 			die(_("core Git rejected index %s"), idx_name);
 		all_packs[pack_id] = new_p;
@@ -982,7 +982,9 @@ static int store_object(
 	}
 
 	for (source = the_repository->objects->sources; source; source = source->next) {
-		if (!packfile_list_find_oid(packfile_store_get_packs(source->files->packed), &oid))
+		struct odb_source_files *files = odb_source_files_downcast(source);
+
+		if (!packfile_list_find_oid(packfile_store_get_packs(files->packed), &oid))
 			continue;
 		e->type = type;
 		e->pack_id = MAX_PACK_ID;
@@ -1187,7 +1189,9 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
 	}
 
 	for (source = the_repository->objects->sources; source; source = source->next) {
-		if (!packfile_list_find_oid(packfile_store_get_packs(source->files->packed), &oid))
+		struct odb_source_files *files = odb_source_files_downcast(source);
+
+		if (!packfile_list_find_oid(packfile_store_get_packs(files->packed), &oid))
 			continue;
 		e->type = OBJ_BLOB;
 		e->pack_id = MAX_PACK_ID;
diff --git a/builtin/grep.c b/builtin/grep.c
index c8d0e51415..61379909b8 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -1218,8 +1218,10 @@ int cmd_grep(int argc,
 			struct odb_source *source;
 
 			odb_prepare_alternates(the_repository->objects);
-			for (source = the_repository->objects->sources; source; source = source->next)
-				packfile_store_prepare(source->files->packed);
+			for (source = the_repository->objects->sources; source; source = source->next) {
+				struct odb_source_files *files = odb_source_files_downcast(source);
+				packfile_store_prepare(files->packed);
+			}
 		}
 
 		start_threads(&opt);
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index f0cce534b2..d1e47279a8 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1637,9 +1637,11 @@ 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 && startup_info->have_repository)
-		packfile_store_load_pack(the_repository->objects->sources->files->packed,
-					 final_index_name, 0);
+	if (do_fsck_object && startup_info->have_repository) {
+		struct odb_source_files *files =
+			odb_source_files_downcast(the_repository->objects->sources);
+		packfile_store_load_pack(files->packed, final_index_name, 0);
+	}
 
 	if (!from_stdin) {
 		printf("%s\n", hash_to_hex(hash));
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 0c3c01cdc9..63fea80b08 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1531,7 +1531,8 @@ static int want_cruft_object_mtime(struct repository *r,
 	struct odb_source *source;
 
 	for (source = r->objects->sources; source; source = source->next) {
-		struct packed_git **cache = packfile_store_get_kept_pack_cache(source->files->packed, flags);
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct packed_git **cache = packfile_store_get_kept_pack_cache(files->packed, flags);
 
 		for (; *cache; cache++) {
 			struct packed_git *p = *cache;
@@ -1753,11 +1754,13 @@ static int want_object_in_pack_mtime(const struct object_id *oid,
 	}
 
 	for (source = the_repository->objects->sources; source; source = source->next) {
-		for (e = source->files->packed->packs.head; e; e = e->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+
+		for (e = files->packed->packs.head; e; e = e->next) {
 			struct packed_git *p = e->pack;
 			want = want_object_in_pack_one(p, oid, exclude, found_pack, found_offset, found_mtime);
 			if (!exclude && want > 0)
-				packfile_list_prepend(&source->files->packed->packs, p);
+				packfile_list_prepend(&files->packed->packs, p);
 			if (want != -1)
 				return want;
 		}
@@ -4337,10 +4340,12 @@ static void add_objects_in_unpacked_packs(void)
 
 	odb_prepare_alternates(to_pack.repo->objects);
 	for (source = to_pack.repo->objects->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+
 		if (!source->local)
 			continue;
 
-		if (packfile_store_for_each_object(source->files->packed, &oi,
+		if (packfile_store_for_each_object(files->packed, &oi,
 						   add_object_in_unpacked_pack, NULL,
 						   ODB_FOR_EACH_OBJECT_PACK_ORDER |
 						   ODB_FOR_EACH_OBJECT_LOCAL_ONLY |
diff --git a/commit-graph.c b/commit-graph.c
index 967eb77047..f8e24145a5 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1980,9 +1980,11 @@ static void fill_oids_from_all_packs(struct write_commit_graph_context *ctx)
 			ctx->approx_nr_objects);
 
 	odb_prepare_alternates(ctx->r->objects);
-	for (source = ctx->r->objects->sources; source; source = source->next)
-		packfile_store_for_each_object(source->files->packed, &oi, add_packed_commits_oi,
+	for (source = ctx->r->objects->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		packfile_store_for_each_object(files->packed, &oi, add_packed_commits_oi,
 					       ctx, ODB_FOR_EACH_OBJECT_PACK_ORDER);
+	}
 
 	if (ctx->progress_done < ctx->approx_nr_objects)
 		display_progress(ctx->progress, ctx->approx_nr_objects);
diff --git a/http.c b/http.c
index b44f493919..8ea1b9d1f6 100644
--- a/http.c
+++ b/http.c
@@ -2543,8 +2543,9 @@ cleanup:
 void http_install_packfile(struct packed_git *p,
 			   struct packfile_list *list_to_remove_from)
 {
+	struct odb_source_files *files = odb_source_files_downcast(the_repository->objects->sources);
 	packfile_list_remove(list_to_remove_from, p);
-	packfile_store_add_pack(the_repository->objects->sources->files->packed, p);
+	packfile_store_add_pack(files->packed, p);
 }
 
 struct http_pack_request *new_http_pack_request(
diff --git a/loose.c b/loose.c
index c921d46b94..07333be696 100644
--- a/loose.c
+++ b/loose.c
@@ -3,6 +3,7 @@
 #include "path.h"
 #include "object-file.h"
 #include "odb.h"
+#include "odb/source-files.h"
 #include "hex.h"
 #include "repository.h"
 #include "wrapper.h"
@@ -49,27 +50,29 @@ static int insert_loose_map(struct odb_source *source,
 			    const struct object_id *oid,
 			    const struct object_id *compat_oid)
 {
-	struct loose_object_map *map = source->files->loose->map;
+	struct odb_source_files *files = odb_source_files_downcast(source);
+	struct loose_object_map *map = files->loose->map;
 	int inserted = 0;
 
 	inserted |= insert_oid_pair(map->to_compat, oid, compat_oid);
 	inserted |= insert_oid_pair(map->to_storage, compat_oid, oid);
 	if (inserted)
-		oidtree_insert(source->files->loose->cache, compat_oid);
+		oidtree_insert(files->loose->cache, compat_oid);
 
 	return inserted;
 }
 
 static int load_one_loose_object_map(struct repository *repo, struct odb_source *source)
 {
+	struct odb_source_files *files = odb_source_files_downcast(source);
 	struct strbuf buf = STRBUF_INIT, path = STRBUF_INIT;
 	FILE *fp;
 
-	if (!source->files->loose->map)
-		loose_object_map_init(&source->files->loose->map);
-	if (!source->files->loose->cache) {
-		ALLOC_ARRAY(source->files->loose->cache, 1);
-		oidtree_init(source->files->loose->cache);
+	if (!files->loose->map)
+		loose_object_map_init(&files->loose->map);
+	if (!files->loose->cache) {
+		ALLOC_ARRAY(files->loose->cache, 1);
+		oidtree_init(files->loose->cache);
 	}
 
 	insert_loose_map(source, repo->hash_algo->empty_tree, repo->compat_hash_algo->empty_tree);
@@ -125,7 +128,8 @@ int repo_read_loose_object_map(struct repository *repo)
 
 int repo_write_loose_object_map(struct repository *repo)
 {
-	kh_oid_map_t *map = repo->objects->sources->files->loose->map->to_compat;
+	struct odb_source_files *files = odb_source_files_downcast(repo->objects->sources);
+	kh_oid_map_t *map = files->loose->map->to_compat;
 	struct lock_file lock;
 	int fd;
 	khiter_t iter;
@@ -231,7 +235,8 @@ int repo_loose_object_map_oid(struct repository *repo,
 	khiter_t pos;
 
 	for (source = repo->objects->sources; source; source = source->next) {
-		struct loose_object_map *loose_map = source->files->loose->map;
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct loose_object_map *loose_map = files->loose->map;
 		if (!loose_map)
 			continue;
 		map = (to == repo->compat_hash_algo) ?
diff --git a/midx.c b/midx.c
index 698d10a1c6..ab8e2611d1 100644
--- a/midx.c
+++ b/midx.c
@@ -95,8 +95,9 @@ static int midx_read_object_offsets(const unsigned char *chunk_start,
 
 struct multi_pack_index *get_multi_pack_index(struct odb_source *source)
 {
-	packfile_store_prepare(source->files->packed);
-	return source->files->packed->midx;
+	struct odb_source_files *files = odb_source_files_downcast(source);
+	packfile_store_prepare(files->packed);
+	return files->packed->midx;
 }
 
 static struct multi_pack_index *load_multi_pack_index_one(struct odb_source *source,
@@ -447,6 +448,7 @@ static uint32_t midx_for_pack(struct multi_pack_index **_m,
 int prepare_midx_pack(struct multi_pack_index *m,
 		      uint32_t pack_int_id)
 {
+	struct odb_source_files *files = odb_source_files_downcast(m->source);
 	struct strbuf pack_name = STRBUF_INIT;
 	struct packed_git *p;
 
@@ -457,10 +459,10 @@ int prepare_midx_pack(struct multi_pack_index *m,
 	if (m->packs[pack_int_id])
 		return 0;
 
-	strbuf_addf(&pack_name, "%s/pack/%s", m->source->path,
+	strbuf_addf(&pack_name, "%s/pack/%s", files->base.path,
 		    m->pack_names[pack_int_id]);
-	p = packfile_store_load_pack(m->source->files->packed,
-				     pack_name.buf, m->source->local);
+	p = packfile_store_load_pack(files->packed,
+				     pack_name.buf, files->base.local);
 	strbuf_release(&pack_name);
 
 	if (!p) {
@@ -703,18 +705,19 @@ int midx_preferred_pack(struct multi_pack_index *m, uint32_t *pack_int_id)
 
 int prepare_multi_pack_index_one(struct odb_source *source)
 {
+	struct odb_source_files *files = odb_source_files_downcast(source);
 	struct repository *r = source->odb->repo;
 
 	prepare_repo_settings(r);
 	if (!r->settings.core_multi_pack_index)
 		return 0;
 
-	if (source->files->packed->midx)
+	if (files->packed->midx)
 		return 1;
 
-	source->files->packed->midx = load_multi_pack_index(source);
+	files->packed->midx = load_multi_pack_index(source);
 
-	return !!source->files->packed->midx;
+	return !!files->packed->midx;
 }
 
 int midx_checksum_valid(struct multi_pack_index *m)
@@ -803,9 +806,10 @@ void clear_midx_file(struct repository *r)
 		struct odb_source *source;
 
 		for (source = r->objects->sources; source; source = source->next) {
-			if (source->files->packed->midx)
-				close_midx(source->files->packed->midx);
-			source->files->packed->midx = NULL;
+			struct odb_source_files *files = odb_source_files_downcast(source);
+			if (files->packed->midx)
+				close_midx(files->packed->midx);
+			files->packed->midx = NULL;
 		}
 	}
 
diff --git a/object-file.c b/object-file.c
index db66ae5ebe..7ef8291a48 100644
--- a/object-file.c
+++ b/object-file.c
@@ -219,8 +219,9 @@ static void *odb_source_loose_map_object(struct odb_source *source,
 					 const struct object_id *oid,
 					 unsigned long *size)
 {
+	struct odb_source_files *files = odb_source_files_downcast(source);
 	const char *p;
-	int fd = open_loose_object(source->files->loose, oid, &p);
+	int fd = open_loose_object(files->loose, oid, &p);
 
 	if (fd < 0)
 		return NULL;
@@ -401,6 +402,7 @@ static int read_object_info_from_path(struct odb_source *source,
 				      struct object_info *oi,
 				      enum object_info_flags flags)
 {
+	struct odb_source_files *files = odb_source_files_downcast(source);
 	int ret;
 	int fd;
 	unsigned long mapsize;
@@ -423,7 +425,7 @@ static int read_object_info_from_path(struct odb_source *source,
 		struct stat st;
 
 		if ((!oi || (!oi->disk_sizep && !oi->mtimep)) && (flags & OBJECT_INFO_QUICK)) {
-			ret = quick_has_loose(source->files->loose, oid) ? 0 : -1;
+			ret = quick_has_loose(files->loose, oid) ? 0 : -1;
 			goto out;
 		}
 
@@ -1866,33 +1868,34 @@ static int append_loose_object(const struct object_id *oid,
 struct oidtree *odb_source_loose_cache(struct odb_source *source,
 				       const struct object_id *oid)
 {
+	struct odb_source_files *files = odb_source_files_downcast(source);
 	int subdir_nr = oid->hash[0];
 	struct strbuf buf = STRBUF_INIT;
-	size_t word_bits = bitsizeof(source->files->loose->subdir_seen[0]);
+	size_t word_bits = bitsizeof(files->loose->subdir_seen[0]);
 	size_t word_index = subdir_nr / word_bits;
 	size_t mask = (size_t)1u << (subdir_nr % word_bits);
 	uint32_t *bitmap;
 
 	if (subdir_nr < 0 ||
-	    (size_t) subdir_nr >= bitsizeof(source->files->loose->subdir_seen))
+	    (size_t) subdir_nr >= bitsizeof(files->loose->subdir_seen))
 		BUG("subdir_nr out of range");
 
-	bitmap = &source->files->loose->subdir_seen[word_index];
+	bitmap = &files->loose->subdir_seen[word_index];
 	if (*bitmap & mask)
-		return source->files->loose->cache;
-	if (!source->files->loose->cache) {
-		ALLOC_ARRAY(source->files->loose->cache, 1);
-		oidtree_init(source->files->loose->cache);
+		return files->loose->cache;
+	if (!files->loose->cache) {
+		ALLOC_ARRAY(files->loose->cache, 1);
+		oidtree_init(files->loose->cache);
 	}
 	strbuf_addstr(&buf, source->path);
 	for_each_file_in_obj_subdir(subdir_nr, &buf,
 				    source->odb->repo->hash_algo,
 				    append_loose_object,
 				    NULL, NULL,
-				    source->files->loose->cache);
+				    files->loose->cache);
 	*bitmap |= mask;
 	strbuf_release(&buf);
-	return source->files->loose->cache;
+	return files->loose->cache;
 }
 
 static void odb_source_loose_clear_cache(struct odb_source_loose *loose)
@@ -1905,7 +1908,8 @@ static void odb_source_loose_clear_cache(struct odb_source_loose *loose)
 
 void odb_source_loose_reprepare(struct odb_source *source)
 {
-	odb_source_loose_clear_cache(source->files->loose);
+	struct odb_source_files *files = odb_source_files_downcast(source);
+	odb_source_loose_clear_cache(files->loose);
 }
 
 static int check_stream_oid(git_zstream *stream,
diff --git a/odb.c b/odb.c
index c9ebc7e741..e5aa8deb88 100644
--- a/odb.c
+++ b/odb.c
@@ -691,7 +691,8 @@ static int do_oid_object_info_extended(struct object_database *odb,
 
 		/* Most likely it's a loose object. */
 		for (source = odb->sources; source; source = source->next) {
-			if (!packfile_store_read_object_info(source->files->packed, real, oi, flags) ||
+			struct odb_source_files *files = odb_source_files_downcast(source);
+			if (!packfile_store_read_object_info(files->packed, real, oi, flags) ||
 			    !odb_source_loose_read_object_info(source, real, oi, flags))
 				return 0;
 		}
@@ -699,9 +700,11 @@ static int do_oid_object_info_extended(struct object_database *odb,
 		/* Not a loose object; someone else may have just packed it. */
 		if (!(flags & OBJECT_INFO_QUICK)) {
 			odb_reprepare(odb->repo->objects);
-			for (source = odb->sources; source; source = source->next)
-				if (!packfile_store_read_object_info(source->files->packed, real, oi, flags))
+			for (source = odb->sources; source; source = source->next) {
+				struct odb_source_files *files = odb_source_files_downcast(source);
+				if (!packfile_store_read_object_info(files->packed, real, oi, flags))
 					return 0;
+			}
 		}
 
 		/*
@@ -962,7 +965,9 @@ int odb_freshen_object(struct object_database *odb,
 
 	odb_prepare_alternates(odb);
 	for (source = odb->sources; source; source = source->next) {
-		if (packfile_store_freshen_object(source->files->packed, oid))
+		struct odb_source_files *files = odb_source_files_downcast(source);
+
+		if (packfile_store_freshen_object(files->packed, oid))
 			return 1;
 
 		if (odb_source_loose_freshen_object(source, oid))
@@ -982,6 +987,8 @@ int odb_for_each_object(struct object_database *odb,
 
 	odb_prepare_alternates(odb);
 	for (struct odb_source *source = odb->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+
 		if (flags & ODB_FOR_EACH_OBJECT_LOCAL_ONLY && !source->local)
 			continue;
 
@@ -992,7 +999,7 @@ int odb_for_each_object(struct object_database *odb,
 				return ret;
 		}
 
-		ret = packfile_store_for_each_object(source->files->packed, request,
+		ret = packfile_store_for_each_object(files->packed, request,
 						     cb, cb_data, flags);
 		if (ret)
 			return ret;
@@ -1090,8 +1097,10 @@ struct object_database *odb_new(struct repository *repo,
 void odb_close(struct object_database *o)
 {
 	struct odb_source *source;
-	for (source = o->sources; source; source = source->next)
-		packfile_store_close(source->files->packed);
+	for (source = o->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		packfile_store_close(files->packed);
+	}
 	close_commit_graph(o);
 }
 
@@ -1148,8 +1157,9 @@ void odb_reprepare(struct object_database *o)
 	odb_prepare_alternates(o);
 
 	for (source = o->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
 		odb_source_loose_reprepare(source);
-		packfile_store_reprepare(source->files->packed);
+		packfile_store_reprepare(files->packed);
 	}
 
 	o->approximate_object_count_valid = 0;
diff --git a/odb/source-files.c b/odb/source-files.c
index cbdaa6850f..a43a197157 100644
--- a/odb/source-files.c
+++ b/odb/source-files.c
@@ -1,5 +1,6 @@
 #include "git-compat-util.h"
 #include "object-file.h"
+#include "odb/source.h"
 #include "odb/source-files.h"
 #include "packfile.h"
 
@@ -9,15 +10,20 @@ void odb_source_files_free(struct odb_source_files *files)
 		return;
 	odb_source_loose_free(files->loose);
 	packfile_store_free(files->packed);
+	odb_source_release(&files->base);
 	free(files);
 }
 
-struct odb_source_files *odb_source_files_new(struct odb_source *source)
+struct odb_source_files *odb_source_files_new(struct object_database *odb,
+					      const char *path,
+					      bool local)
 {
 	struct odb_source_files *files;
+
 	CALLOC_ARRAY(files, 1);
-	files->source = source;
-	files->loose = odb_source_loose_new(source);
-	files->packed = packfile_store_new(source);
+	odb_source_init(&files->base, odb, path, local);
+	files->loose = odb_source_loose_new(&files->base);
+	files->packed = packfile_store_new(&files->base);
+
 	return files;
 }
diff --git a/odb/source-files.h b/odb/source-files.h
index 0b8bf773ca..58753d40de 100644
--- a/odb/source-files.h
+++ b/odb/source-files.h
@@ -1,8 +1,9 @@
 #ifndef ODB_SOURCE_FILES_H
 #define ODB_SOURCE_FILES_H
 
+#include "odb/source.h"
+
 struct odb_source_loose;
-struct odb_source;
 struct packfile_store;
 
 /*
@@ -10,15 +11,26 @@ struct packfile_store;
  * packfiles. It is the default backend used by Git to store objects.
  */
 struct odb_source_files {
-	struct odb_source *source;
+	struct odb_source base;
 	struct odb_source_loose *loose;
 	struct packfile_store *packed;
 };
 
 /* Allocate and initialize a new object source. */
-struct odb_source_files *odb_source_files_new(struct odb_source *source);
+struct odb_source_files *odb_source_files_new(struct object_database *odb,
+					      const char *path,
+					      bool local);
 
 /* Free the object source and release all associated resources. */
 void odb_source_files_free(struct odb_source_files *files);
 
+/*
+ * Cast the given object database source to the files backend. This will cause
+ * a BUG in case the source doesn't use this backend.
+ */
+static inline struct odb_source_files *odb_source_files_downcast(struct odb_source *source)
+{
+	return container_of(source, struct odb_source_files, base);
+}
+
 #endif
diff --git a/odb/source.c b/odb/source.c
index 9d7fd19f45..d8b2176a94 100644
--- a/odb/source.c
+++ b/odb/source.c
@@ -1,5 +1,6 @@
 #include "git-compat-util.h"
 #include "object-file.h"
+#include "odb/source-files.h"
 #include "odb/source.h"
 #include "packfile.h"
 
@@ -7,20 +8,31 @@ struct odb_source *odb_source_new(struct object_database *odb,
 				  const char *path,
 				  bool local)
 {
-	struct odb_source *source;
+	return &odb_source_files_new(odb, path, local)->base;
+}
 
-	CALLOC_ARRAY(source, 1);
+void odb_source_init(struct odb_source *source,
+		     struct object_database *odb,
+		     const char *path,
+		     bool local)
+{
 	source->odb = odb;
 	source->local = local;
 	source->path = xstrdup(path);
-	source->files = odb_source_files_new(source);
-
-	return source;
 }
 
 void odb_source_free(struct odb_source *source)
 {
-	free(source->path);
-	odb_source_files_free(source->files);
-	free(source);
+	struct odb_source_files *files;
+	if (!source)
+		return;
+	files = odb_source_files_downcast(source);
+	odb_source_files_free(files);
+}
+
+void odb_source_release(struct odb_source *source)
+{
+	if (!source)
+		return;
+	free(source->path);
 }
diff --git a/odb/source.h b/odb/source.h
index 1c34265189..e6698b73a3 100644
--- a/odb/source.h
+++ b/odb/source.h
@@ -1,8 +1,6 @@
 #ifndef ODB_SOURCE_H
 #define ODB_SOURCE_H
 
-#include "odb/source-files.h"
-
 /*
  * The source is the part of the object database that stores the actual
  * objects. It thus encapsulates the logic to read and write the specific
@@ -21,9 +19,6 @@ struct odb_source {
 	/* Object database that owns this object source. */
 	struct object_database *odb;
 
-	/* The backend used to store objects. */
-	struct odb_source_files *files;
-
 	/*
 	 * Figure out whether this is the local source of the owning
 	 * repository, which would typically be its ".git/objects" directory.
@@ -53,7 +48,31 @@ struct odb_source *odb_source_new(struct object_database *odb,
 				  const char *path,
 				  bool local);
 
-/* Free the object database source, releasing all associated resources. */
+/*
+ * Initialize the source for the given object database located at `path`.
+ * `local` indicates whether or not the source is the local and thus primary
+ * object source of the object database.
+ *
+ * This function is only supposed to be called by specific object source
+ * implementations.
+ */
+void odb_source_init(struct odb_source *source,
+		     struct object_database *odb,
+		     const char *path,
+		     bool local);
+
+/*
+ * Free the object database source, releasing all associated resources and
+ * freeing the structure itself.
+ */
 void odb_source_free(struct odb_source *source);
 
+/*
+ * Release the object database source, releasing all associated resources.
+ *
+ * This function is only supposed to be called by specific object source
+ * implementations.
+ */
+void odb_source_release(struct odb_source *source);
+
 #endif
diff --git a/odb/streaming.c b/odb/streaming.c
index 26b0a1a0f5..19cda9407d 100644
--- a/odb/streaming.c
+++ b/odb/streaming.c
@@ -187,7 +187,8 @@ static int istream_source(struct odb_read_stream **out,
 
 	odb_prepare_alternates(odb);
 	for (source = odb->sources; source; source = source->next) {
-		if (!packfile_store_read_object_stream(out, source->files->packed, oid) ||
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		if (!packfile_store_read_object_stream(out, files->packed, oid) ||
 		    !odb_source_loose_read_object_stream(out, source, oid))
 			return 0;
 	}
diff --git a/packfile.c b/packfile.c
index 4e1f6087ed..da1c0dfa39 100644
--- a/packfile.c
+++ b/packfile.c
@@ -362,9 +362,11 @@ static int unuse_one_window(struct object_database *odb)
 	struct packed_git *lru_p = NULL;
 	struct pack_window *lru_w = NULL, *lru_l = NULL;
 
-	for (source = odb->sources; source; source = source->next)
-		for (e = source->files->packed->packs.head; e; e = e->next)
+	for (source = odb->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		for (e = files->packed->packs.head; e; e = e->next)
 			scan_windows(e->pack, &lru_p, &lru_w, &lru_l);
+	}
 
 	if (lru_p) {
 		munmap(lru_w->base, lru_w->len);
@@ -537,7 +539,8 @@ static int close_one_pack(struct repository *r)
 	int accept_windows_inuse = 1;
 
 	for (source = r->objects->sources; source; source = source->next) {
-		for (e = source->files->packed->packs.head; e; e = e->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		for (e = files->packed->packs.head; e; e = e->next) {
 			if (e->pack->pack_fd == -1)
 				continue;
 			find_lru_pack(e->pack, &lru_p, &mru_w, &accept_windows_inuse);
@@ -987,13 +990,14 @@ static void prepare_pack(const char *full_name, size_t full_name_len,
 			 const char *file_name, void *_data)
 {
 	struct prepare_pack_data *data = (struct prepare_pack_data *)_data;
+	struct odb_source_files *files = odb_source_files_downcast(data->source);
 	size_t base_len = full_name_len;
 
 	if (strip_suffix_mem(full_name, &base_len, ".idx") &&
-	    !(data->source->files->packed->midx &&
-	      midx_contains_pack(data->source->files->packed->midx, file_name))) {
+	    !(files->packed->midx &&
+	      midx_contains_pack(files->packed->midx, file_name))) {
 		char *trimmed_path = xstrndup(full_name, full_name_len);
-		packfile_store_load_pack(data->source->files->packed,
+		packfile_store_load_pack(files->packed,
 					 trimmed_path, data->source->local);
 		free(trimmed_path);
 	}
@@ -1247,8 +1251,10 @@ const struct packed_git *has_packed_and_bad(struct repository *r,
 	struct odb_source *source;
 
 	for (source = r->objects->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
 		struct packfile_list_entry *e;
-		for (e = source->files->packed->packs.head; e; e = e->next)
+
+		for (e = files->packed->packs.head; e; e = e->next)
 			if (oidset_contains(&e->pack->bad_objects, oid))
 				return e->pack;
 	}
@@ -2254,7 +2260,8 @@ int has_object_pack(struct repository *r, const struct object_id *oid)
 
 	odb_prepare_alternates(r->objects);
 	for (source = r->objects->sources; source; source = source->next) {
-		int ret = find_pack_entry(source->files->packed, oid, &e);
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		int ret = find_pack_entry(files->packed, oid, &e);
 		if (ret)
 			return ret;
 	}
@@ -2269,9 +2276,10 @@ int has_object_kept_pack(struct repository *r, const struct object_id *oid,
 	struct pack_entry e;
 
 	for (source = r->objects->sources; source; source = source->next) {
+		struct odb_source_files *files = odb_source_files_downcast(source);
 		struct packed_git **cache;
 
-		cache = packfile_store_get_kept_pack_cache(source->files->packed, flags);
+		cache = packfile_store_get_kept_pack_cache(files->packed, flags);
 
 		for (; *cache; cache++) {
 			struct packed_git *p = *cache;
diff --git a/packfile.h b/packfile.h
index e8de06ee86..64a31738c0 100644
--- a/packfile.h
+++ b/packfile.h
@@ -4,6 +4,7 @@
 #include "list.h"
 #include "object.h"
 #include "odb.h"
+#include "odb/source-files.h"
 #include "oidset.h"
 #include "repository.h"
 #include "strmap.h"
@@ -192,7 +193,8 @@ static inline struct repo_for_each_pack_data repo_for_eack_pack_data_init(struct
 	odb_prepare_alternates(repo->objects);
 
 	for (struct odb_source *source = repo->objects->sources; source; source = source->next) {
-		struct packfile_list_entry *entry = packfile_store_get_packs(source->files->packed);
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct packfile_list_entry *entry = packfile_store_get_packs(files->packed);
 		if (!entry)
 			continue;
 		data.source = source;
@@ -212,7 +214,8 @@ static inline void repo_for_each_pack_data_next(struct repo_for_each_pack_data *
 		return;
 
 	for (source = data->source->next; source; source = source->next) {
-		struct packfile_list_entry *entry = packfile_store_get_packs(source->files->packed);
+		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct packfile_list_entry *entry = packfile_store_get_packs(files->packed);
 		if (!entry)
 			continue;
 		data->source = source;