patch, 49 partsrepack: prepare for incremental MIDX-based repacking

diff --git a/builtin/repack.c b/builtin/repack.c
index e8730808c5..305782b2c9 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -1247,7 +1247,7 @@ static const char *find_pack_prefix(const char *packdir, const char *packtmp)
 int cmd_repack(int argc,
 	       const char **argv,
 	       const char *prefix,
-	       struct repository *repo UNUSED)
+	       struct repository *repo)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
@@ -1344,7 +1344,7 @@ int cmd_repack(int argc,
 
 	list_objects_filter_init(&po_args.filter_options);
 
-	repo_config(the_repository, repack_config, &cruft_po_args);
+	repo_config(repo, repack_config, &cruft_po_args);
 
 	argc = parse_options(argc, argv, prefix, builtin_repack_options,
 				git_repack_usage, 0);
@@ -1354,7 +1354,7 @@ int cmd_repack(int argc,
 	po_args.depth = xstrdup_or_null(opt_depth);
 	po_args.threads = xstrdup_or_null(opt_threads);
 
-	if (delete_redundant && the_repository->repository_format_precious_objects)
+	if (delete_redundant && repo->repository_format_precious_objects)
 		die(_("cannot delete packs in a precious-objects repo"));
 
 	die_for_incompatible_opt3(unpack_unreachable || (pack_everything & LOOSEN_UNREACHABLE), "-A",
@@ -1376,7 +1376,7 @@ int cmd_repack(int argc,
 		die(_(incremental_bitmap_conflict_error));
 
 	if (write_bitmaps && po_args.local &&
-	    odb_has_alternates(the_repository->objects)) {
+	    odb_has_alternates(repo->objects)) {
 		/*
 		 * When asked to do a local repack, but we have
 		 * packfiles that are inherited from an alternate, then
@@ -1391,7 +1391,8 @@ int cmd_repack(int argc,
 	if (write_midx && write_bitmaps) {
 		struct strbuf path = STRBUF_INIT;
 
-		strbuf_addf(&path, "%s/%s_XXXXXX", repo_get_object_directory(the_repository),
+		strbuf_addf(&path, "%s/%s_XXXXXX",
+			    repo_get_object_directory(repo),
 			    "bitmap-ref-tips");
 
 		refs_snapshot = xmks_tempfile(path.buf);
@@ -1400,7 +1401,7 @@ int cmd_repack(int argc,
 		strbuf_release(&path);
 	}
 
-	packdir = mkpathdup("%s/pack", repo_get_object_directory(the_repository));
+	packdir = mkpathdup("%s/pack", repo_get_object_directory(repo));
 	packtmp_name = xstrfmt(".tmp-%d-pack", (int)getpid());
 	packtmp = mkpathdup("%s/%s", packdir, packtmp_name);
 
@@ -1439,7 +1440,7 @@ int cmd_repack(int argc,
 		strvec_push(&cmd.args, "--reflog");
 		strvec_push(&cmd.args, "--indexed-objects");
 	}
-	if (repo_has_promisor_remote(the_repository))
+	if (repo_has_promisor_remote(repo))
 		strvec_push(&cmd.args, "--exclude-promisor-objects");
 	if (!write_midx) {
 		if (write_bitmaps > 0)
@@ -1535,7 +1536,7 @@ int cmd_repack(int argc,
 		 * midx_has_unknown_packs() will make the decision for
 		 * us.
 		 */
-		if (!get_multi_pack_index(the_repository->objects->sources))
+		if (!get_multi_pack_index(repo->objects->sources))
 			midx_must_contain_cruft = 1;
 	}
 
@@ -1618,9 +1619,9 @@ int cmd_repack(int argc,
 
 	string_list_sort(&names);
 
-	if (get_multi_pack_index(the_repository->objects->sources)) {
+	if (get_multi_pack_index(repo->objects->sources)) {
 		struct multi_pack_index *m =
-			get_multi_pack_index(the_repository->objects->sources);
+			get_multi_pack_index(repo->objects->sources);
 
 		ALLOC_ARRAY(midx_pack_names,
 			    m->num_packs + m->num_packs_in_base);
@@ -1631,7 +1632,7 @@ int cmd_repack(int argc,
 					xstrdup(m->pack_names[i]);
 	}
 
-	close_object_store(the_repository->objects);
+	close_object_store(repo->objects);
 
 	/*
 	 * Ok we have prepared all new packfiles.
@@ -1688,7 +1689,7 @@ int cmd_repack(int argc,
 			goto cleanup;
 	}
 
-	odb_reprepare(the_repository->objects);
+	odb_reprepare(repo->objects);
 
 	if (delete_redundant) {
 		int opts = 0;
@@ -1704,18 +1705,18 @@ int cmd_repack(int argc,
 		if (!keep_unreachable &&
 		    (!(pack_everything & LOOSEN_UNREACHABLE) ||
 		     unpack_unreachable) &&
-		    is_repository_shallow(the_repository))
+		    is_repository_shallow(repo))
 			prune_shallow(PRUNE_QUICK);
 	}
 
 	if (run_update_server_info)
-		update_server_info(the_repository, 0);
+		update_server_info(repo, 0);
 
 	if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0)) {
 		unsigned flags = 0;
 		if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX_WRITE_INCREMENTAL, 0))
 			flags |= MIDX_WRITE_INCREMENTAL;
-		write_midx_file(the_repository->objects->sources,
+		write_midx_file(repo->objects->sources,
 				NULL, NULL, flags);
 	}
 

diff --git a/builtin/repack.c b/builtin/repack.c
index 305782b2c9..7223553bed 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -126,6 +126,7 @@ static void pack_objects_args_release(struct pack_objects_args *args)
 }
 
 struct existing_packs {
+	struct repository *repo;
 	struct string_list kept_packs;
 	struct string_list non_kept_packs;
 	struct string_list cruft_packs;
@@ -265,7 +266,7 @@ static void existing_packs_release(struct existing_packs *existing)
 static void collect_pack_filenames(struct existing_packs *existing,
 				   const struct string_list *extra_keep)
 {
-	struct packfile_store *packs = the_repository->objects->packfiles;
+	struct packfile_store *packs = existing->repo->objects->packfiles;
 	struct packed_git *p;
 	struct strbuf buf = STRBUF_INIT;
 
@@ -498,7 +499,7 @@ static void init_pack_geometry(struct pack_geometry *geometry,
 			       struct existing_packs *existing,
 			       const struct pack_objects_args *args)
 {
-	struct packfile_store *packs = the_repository->objects->packfiles;
+	struct packfile_store *packs = existing->repo->objects->packfiles;
 	struct packed_git *p;
 	struct strbuf buf = STRBUF_INIT;
 
@@ -1139,7 +1140,7 @@ static int write_filtered_pack(const struct pack_objects_args *args,
 static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
 				      struct existing_packs *existing)
 {
-	struct packfile_store *packs = the_repository->objects->packfiles;
+	struct packfile_store *packs = existing->repo->objects->packfiles;
 	struct packed_git *p;
 	struct strbuf buf = STRBUF_INIT;
 	size_t i;
@@ -1405,6 +1406,7 @@ int cmd_repack(int argc,
 	packtmp_name = xstrfmt(".tmp-%d-pack", (int)getpid());
 	packtmp = mkpathdup("%s/%s", packdir, packtmp_name);
 
+	existing.repo = repo;
 	collect_pack_filenames(&existing, &keep_pack_list);
 
 	if (geometry.split_factor) {

diff --git a/builtin/repack.c b/builtin/repack.c
index 7223553bed..113f5fc67f 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -771,6 +771,7 @@ static int midx_has_unknown_packs(char **midx_pack_names,
 }
 
 struct midx_snapshot_ref_data {
+	struct repository *repo;
 	struct tempfile *f;
 	struct oidset seen;
 	int preferred;
@@ -784,13 +785,13 @@ static int midx_snapshot_ref_one(const char *refname UNUSED,
 	struct midx_snapshot_ref_data *data = _data;
 	struct object_id peeled;
 
-	if (!peel_iterated_oid(the_repository, oid, &peeled))
+	if (!peel_iterated_oid(data->repo, oid, &peeled))
 		oid = &peeled;
 
 	if (oidset_insert(&data->seen, oid))
 		return 0; /* already seen */
 
-	if (odb_read_object_info(the_repository->objects, oid, NULL) != OBJ_COMMIT)
+	if (odb_read_object_info(data->repo->objects, oid, NULL) != OBJ_COMMIT)
 		return 0;
 
 	fprintf(data->f->fp, "%s%s\n", data->preferred ? "+" : "",
@@ -799,11 +800,12 @@ static int midx_snapshot_ref_one(const char *refname UNUSED,
 	return 0;
 }
 
-static void midx_snapshot_refs(struct tempfile *f)
+static void midx_snapshot_refs(struct repository *repo, struct tempfile *f)
 {
 	struct midx_snapshot_ref_data data;
-	const struct string_list *preferred = bitmap_preferred_tips(the_repository);
+	const struct string_list *preferred = bitmap_preferred_tips(repo);
 
+	data.repo = repo;
 	data.f = f;
 	data.preferred = 0;
 	oidset_init(&data.seen, 0);
@@ -817,13 +819,13 @@ static void midx_snapshot_refs(struct tempfile *f)
 
 		data.preferred = 1;
 		for_each_string_list_item(item, preferred)
-			refs_for_each_ref_in(get_main_ref_store(the_repository),
+			refs_for_each_ref_in(get_main_ref_store(repo),
 					     item->string,
 					     midx_snapshot_ref_one, &data);
 		data.preferred = 0;
 	}
 
-	refs_for_each_ref(get_main_ref_store(the_repository),
+	refs_for_each_ref(get_main_ref_store(repo),
 			  midx_snapshot_ref_one, &data);
 
 	if (close_tempfile_gently(f)) {
@@ -1397,7 +1399,7 @@ int cmd_repack(int argc,
 			    "bitmap-ref-tips");
 
 		refs_snapshot = xmks_tempfile(path.buf);
-		midx_snapshot_refs(refs_snapshot);
+		midx_snapshot_refs(repo, refs_snapshot);
 
 		strbuf_release(&path);
 	}

diff --git a/builtin/repack.c b/builtin/repack.c
index 113f5fc67f..93802531e1 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -221,33 +221,35 @@ static void mark_packs_for_deletion(struct existing_packs *existing,
 	mark_packs_for_deletion_1(names, &existing->cruft_packs);
 }
 
-static void remove_redundant_pack(const char *dir_name, const char *base_name)
+static void remove_redundant_pack(struct repository *repo,
+				  const char *dir_name, const char *base_name)
 {
 	struct strbuf buf = STRBUF_INIT;
-	struct odb_source *source = the_repository->objects->sources;
+	struct odb_source *source = repo->objects->sources;
 	struct multi_pack_index *m = get_multi_pack_index(source);
 	strbuf_addf(&buf, "%s.pack", base_name);
 	if (m && source->local && midx_contains_pack(m, buf.buf))
-		clear_midx_file(the_repository);
+		clear_midx_file(repo);
 	strbuf_insertf(&buf, 0, "%s/", dir_name);
 	unlink_pack_path(buf.buf, 1);
 	strbuf_release(&buf);
 }
 
-static void remove_redundant_packs_1(struct string_list *packs)
+static void remove_redundant_packs_1(struct repository *repo,
+				     struct string_list *packs)
 {
 	struct string_list_item *item;
 	for_each_string_list_item(item, packs) {
 		if (!pack_is_marked_for_deletion(item))
 			continue;
-		remove_redundant_pack(packdir, item->string);
+		remove_redundant_pack(repo, packdir, item->string);
 	}
 }
 
 static void remove_redundant_existing_packs(struct existing_packs *existing)
 {
-	remove_redundant_packs_1(&existing->non_kept_packs);
-	remove_redundant_packs_1(&existing->cruft_packs);
+	remove_redundant_packs_1(existing->repo, &existing->non_kept_packs);
+	remove_redundant_packs_1(existing->repo, &existing->cruft_packs);
 }
 
 static void existing_packs_release(struct existing_packs *existing)
@@ -685,7 +687,7 @@ static void geometry_remove_redundant_packs(struct pack_geometry *geometry,
 		    (string_list_has_string(&existing->kept_packs, buf.buf)))
 			continue;
 
-		remove_redundant_pack(packdir, buf.buf);
+		remove_redundant_pack(existing->repo, packdir, buf.buf);
 	}
 
 	strbuf_release(&buf);

diff --git a/builtin/repack.c b/builtin/repack.c
index 93802531e1..4f08b57ddb 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -407,7 +407,8 @@ static int has_pack_ext(const struct generated_pack_data *data,
 	BUG("unknown pack extension: '%s'", ext);
 }
 
-static void repack_promisor_objects(const struct pack_objects_args *args,
+static void repack_promisor_objects(struct repository *repo,
+				    const struct pack_objects_args *args,
 				    struct string_list *names)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
@@ -424,7 +425,7 @@ static void repack_promisor_objects(const struct pack_objects_args *args,
 	 * {type -> existing pack order} ordering when computing deltas instead
 	 * of a {type -> size} ordering, which may produce better deltas.
 	 */
-	for_each_packed_object(the_repository, write_oid, &cmd,
+	for_each_packed_object(repo, write_oid, &cmd,
 			       FOR_EACH_OBJECT_PROMISOR_ONLY);
 
 	if (cmd.in == -1) {
@@ -1458,7 +1459,7 @@ int cmd_repack(int argc,
 		strvec_push(&cmd.args, "--delta-islands");
 
 	if (pack_everything & ALL_INTO_ONE) {
-		repack_promisor_objects(&po_args, &names);
+		repack_promisor_objects(repo, &po_args, &names);
 
 		if (has_existing_non_kept_packs(&existing) &&
 		    delete_redundant &&

diff --git a/builtin/repack.c b/builtin/repack.c
index 4f08b57ddb..094f5a0cc2 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -168,11 +168,12 @@ static int pack_is_retained(struct string_list_item *item)
 	return (uintptr_t)item->util & RETAIN_PACK;
 }
 
-static void mark_packs_for_deletion_1(struct string_list *names,
+static void mark_packs_for_deletion_1(const struct git_hash_algo *algop,
+				      struct string_list *names,
 				      struct string_list *list)
 {
 	struct string_list_item *item;
-	const int hexsz = the_hash_algo->hexsz;
+	const int hexsz = algop->hexsz;
 
 	for_each_string_list_item(item, list) {
 		char *sha1;
@@ -217,8 +218,9 @@ static void mark_packs_for_deletion(struct existing_packs *existing,
 				    struct string_list *names)
 
 {
-	mark_packs_for_deletion_1(names, &existing->non_kept_packs);
-	mark_packs_for_deletion_1(names, &existing->cruft_packs);
+	const struct git_hash_algo *algop = existing->repo->hash_algo;
+	mark_packs_for_deletion_1(algop, names, &existing->non_kept_packs);
+	mark_packs_for_deletion_1(algop, names, &existing->cruft_packs);
 }
 
 static void remove_redundant_pack(struct repository *repo,

diff --git a/builtin/repack.c b/builtin/repack.c
index 094f5a0cc2..7d62959dc2 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -339,6 +339,11 @@ static void prepare_pack_objects(struct child_process *cmd,
 	cmd->out = -1;
 }
 
+struct write_oid_context {
+	struct child_process *cmd;
+	const struct git_hash_algo *algop;
+};
+
 /*
  * Write oid to the given struct child_process's stdin, starting it first if
  * necessary.
@@ -347,14 +352,15 @@ static int write_oid(const struct object_id *oid,
 		     struct packed_git *pack UNUSED,
 		     uint32_t pos UNUSED, void *data)
 {
-	struct child_process *cmd = data;
+	struct write_oid_context *ctx = data;
+	struct child_process *cmd = ctx->cmd;
 
 	if (cmd->in == -1) {
 		if (start_command(cmd))
 			die(_("could not start pack-objects to repack promisor objects"));
 	}
 
-	if (write_in_full(cmd->in, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
+	if (write_in_full(cmd->in, oid_to_hex(oid), ctx->algop->hexsz) < 0 ||
 	    write_in_full(cmd->in, "\n", 1) < 0)
 		die(_("failed to feed promisor objects to pack-objects"));
 	return 0;
@@ -413,6 +419,7 @@ static void repack_promisor_objects(struct repository *repo,
 				    const struct pack_objects_args *args,
 				    struct string_list *names)
 {
+	struct write_oid_context ctx;
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	FILE *out;
 	struct strbuf line = STRBUF_INIT;
@@ -427,7 +434,9 @@ static void repack_promisor_objects(struct repository *repo,
 	 * {type -> existing pack order} ordering when computing deltas instead
 	 * of a {type -> size} ordering, which may produce better deltas.
 	 */
-	for_each_packed_object(repo, write_oid, &cmd,
+	ctx.cmd = &cmd;
+	ctx.algop = repo->hash_algo;
+	for_each_packed_object(repo, write_oid, &ctx,
 			       FOR_EACH_OBJECT_PROMISOR_ONLY);
 
 	if (cmd.in == -1) {

diff --git a/builtin/repack.c b/builtin/repack.c
index 7d62959dc2..a7e94ed03c 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -452,7 +452,7 @@ static void repack_promisor_objects(struct repository *repo,
 		struct string_list_item *item;
 		char *promisor_name;
 
-		if (line.len != the_hash_algo->hexsz)
+		if (line.len != repo->hash_algo->hexsz)
 			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
 		item = string_list_append(names, line.buf);
 

diff --git a/builtin/repack.c b/builtin/repack.c
index a7e94ed03c..a043704aa8 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -1073,7 +1073,8 @@ static void remove_redundant_bitmaps(struct string_list *include,
 	strbuf_release(&path);
 }
 
-static int finish_pack_objects_cmd(struct child_process *cmd,
+static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
+				   struct child_process *cmd,
 				   struct string_list *names,
 				   int local)
 {
@@ -1084,7 +1085,7 @@ static int finish_pack_objects_cmd(struct child_process *cmd,
 	while (strbuf_getline_lf(&line, out) != EOF) {
 		struct string_list_item *item;
 
-		if (line.len != the_hash_algo->hexsz)
+		if (line.len != algop->hexsz)
 			die(_("repack: Expecting full hex object ID lines only "
 			      "from pack-objects."));
 		/*
@@ -1150,7 +1151,8 @@ static int write_filtered_pack(const struct pack_objects_args *args,
 		fprintf(in, "%s%s.pack\n", caret, item->string);
 	fclose(in);
 
-	return finish_pack_objects_cmd(&cmd, names, local);
+	return finish_pack_objects_cmd(existing->repo->hash_algo, &cmd, names,
+				       local);
 }
 
 static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
@@ -1247,7 +1249,8 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 		fprintf(in, "%s.pack\n", item->string);
 	fclose(in);
 
-	return finish_pack_objects_cmd(&cmd, names, local);
+	return finish_pack_objects_cmd(existing->repo->hash_algo, &cmd, names,
+				       local);
 }
 
 static const char *find_pack_prefix(const char *packdir, const char *packtmp)
@@ -1534,7 +1537,7 @@ int cmd_repack(int argc,
 		fclose(in);
 	}
 
-	ret = finish_pack_objects_cmd(&cmd, &names, 1);
+	ret = finish_pack_objects_cmd(repo->hash_algo, &cmd, &names, 1);
 	if (ret)
 		goto cleanup;
 

diff --git a/builtin/repack.c b/builtin/repack.c
index a043704aa8..0d35f15b4b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -683,12 +683,14 @@ static void geometry_remove_redundant_packs(struct pack_geometry *geometry,
 					    struct string_list *names,
 					    struct existing_packs *existing)
 {
+	const struct git_hash_algo *algop = existing->repo->hash_algo;
 	struct strbuf buf = STRBUF_INIT;
 	uint32_t i;
 
 	for (i = 0; i < geometry->split; i++) {
 		struct packed_git *p = geometry->pack[i];
-		if (string_list_has_string(names, hash_to_hex(p->hash)))
+		if (string_list_has_string(names, hash_to_hex_algop(p->hash,
+								    algop)))
 			continue;
 
 		strbuf_reset(&buf);

Makefile, builtin/repack.c, meson.build, repack.c, repack.h

diff --git a/Makefile b/Makefile
index 555b7f4dc3..b220f0f7d8 100644
--- a/Makefile
+++ b/Makefile
@@ -1136,6 +1136,7 @@ LIB_OBJS += refs/packed-backend.o
 LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
+LIB_OBJS += repack.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o
 LIB_OBJS += repository.o
diff --git a/builtin/repack.c b/builtin/repack.c
index 0d35f15b4b..6dfcb3327e 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -19,6 +19,7 @@
 #include "prune-packed.h"
 #include "odb.h"
 #include "promisor-remote.h"
+#include "repack.h"
 #include "shallow.h"
 #include "pack.h"
 #include "pack-bitmap.h"
@@ -53,21 +54,6 @@ static const char incremental_bitmap_conflict_error[] = N_(
 "--no-write-bitmap-index or disable the pack.writeBitmaps configuration."
 );
 
-struct pack_objects_args {
-	char *window;
-	char *window_memory;
-	char *depth;
-	char *threads;
-	unsigned long max_pack_size;
-	int no_reuse_delta;
-	int no_reuse_object;
-	int quiet;
-	int local;
-	int name_hash_version;
-	int path_walk;
-	struct list_objects_filter_options filter_options;
-};
-
 static int repack_config(const char *var, const char *value,
 			 const struct config_context *ctx, void *cb)
 {
@@ -116,15 +102,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-static void pack_objects_args_release(struct pack_objects_args *args)
-{
-	free(args->window);
-	free(args->window_memory);
-	free(args->depth);
-	free(args->threads);
-	list_objects_filter_release(&args->filter_options);
-}
-
 struct existing_packs {
 	struct repository *repo;
 	struct string_list kept_packs;
diff --git a/meson.build b/meson.build
index e8ec0eca16..8ab287a2ed 100644
--- a/meson.build
+++ b/meson.build
@@ -462,6 +462,7 @@ libgit_sources = [
   'reftable/tree.c',
   'reftable/writer.c',
   'remote.c',
+  'repack.c',
   'replace-object.c',
   'repo-settings.c',
   'repository.c',
diff --git a/repack.c b/repack.c
new file mode 100644
index 0000000000..a1f5b796fb
--- /dev/null
+++ b/repack.c
@@ -0,0 +1,11 @@
+#include "git-compat-util.h"
+#include "repack.h"
+
+void pack_objects_args_release(struct pack_objects_args *args)
+{
+	free(args->window);
+	free(args->window_memory);
+	free(args->depth);
+	free(args->threads);
+	list_objects_filter_release(&args->filter_options);
+}
diff --git a/repack.h b/repack.h
new file mode 100644
index 0000000000..421d439d5a
--- /dev/null
+++ b/repack.h
@@ -0,0 +1,23 @@
+#ifndef REPACK_H
+#define REPACK_H
+
+#include "list-objects-filter-options.h"
+
+struct pack_objects_args {
+	char *window;
+	char *window_memory;
+	char *depth;
+	char *threads;
+	unsigned long max_pack_size;
+	int no_reuse_delta;
+	int no_reuse_object;
+	int quiet;
+	int local;
+	int name_hash_version;
+	int path_walk;
+	struct list_objects_filter_options filter_options;
+};
+
+void pack_objects_args_release(struct pack_objects_args *args);
+
+#endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index 6dfcb3327e..af6de8d77a 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -54,10 +54,16 @@ static const char incremental_bitmap_conflict_error[] = N_(
 "--no-write-bitmap-index or disable the pack.writeBitmaps configuration."
 );
 
+struct repack_config_ctx {
+	struct pack_objects_args *po_args;
+	struct pack_objects_args *cruft_po_args;
+};
+
 static int repack_config(const char *var, const char *value,
 			 const struct config_context *ctx, void *cb)
 {
-	struct pack_objects_args *cruft_po_args = cb;
+	struct repack_config_ctx *repack_ctx = cb;
+	struct pack_objects_args *cruft_po_args = repack_ctx->cruft_po_args;
 	if (!strcmp(var, "repack.usedeltabaseoffset")) {
 		delta_base_offset = git_config_bool(var, value);
 		return 0;
@@ -1260,6 +1266,7 @@ int cmd_repack(int argc,
 	size_t midx_pack_names_nr = 0;
 
 	/* variables to be filled by option parsing */
+	struct repack_config_ctx config_ctx;
 	int delete_redundant = 0;
 	const char *unpack_unreachable = NULL;
 	int keep_unreachable = 0;
@@ -1343,7 +1350,11 @@ int cmd_repack(int argc,
 
 	list_objects_filter_init(&po_args.filter_options);
 
-	repo_config(repo, repack_config, &cruft_po_args);
+	memset(&config_ctx, 0, sizeof(config_ctx));
+	config_ctx.po_args = &po_args;
+	config_ctx.cruft_po_args = &cruft_po_args;
+
+	repo_config(repo, repack_config, &config_ctx);
 
 	argc = parse_options(argc, argv, prefix, builtin_repack_options,
 				git_repack_usage, 0);

builtin/repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index af6de8d77a..f4af830353 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -34,7 +34,6 @@
 #define RETAIN_PACK 2
 
 static int pack_everything;
-static int delta_base_offset = 1;
 static int pack_kept_objects = -1;
 static int write_bitmaps = -1;
 static int use_delta_islands;
@@ -63,9 +62,10 @@ static int repack_config(const char *var, const char *value,
 			 const struct config_context *ctx, void *cb)
 {
 	struct repack_config_ctx *repack_ctx = cb;
+	struct pack_objects_args *po_args = repack_ctx->po_args;
 	struct pack_objects_args *cruft_po_args = repack_ctx->cruft_po_args;
 	if (!strcmp(var, "repack.usedeltabaseoffset")) {
-		delta_base_offset = git_config_bool(var, value);
+		po_args->delta_base_offset = git_config_bool(var, value);
 		return 0;
 	}
 	if (!strcmp(var, "repack.packkeptobjects")) {
@@ -315,7 +315,7 @@ static void prepare_pack_objects(struct child_process *cmd,
 		strvec_push(&cmd->args,  "--local");
 	if (args->quiet)
 		strvec_push(&cmd->args,  "--quiet");
-	if (delta_base_offset)
+	if (args->delta_base_offset)
 		strvec_push(&cmd->args,  "--delta-base-offset");
 	strvec_push(&cmd->args, out);
 	cmd->git_cmd = 1;
@@ -1271,8 +1271,8 @@ int cmd_repack(int argc,
 	const char *unpack_unreachable = NULL;
 	int keep_unreachable = 0;
 	struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
-	struct pack_objects_args po_args = { 0 };
-	struct pack_objects_args cruft_po_args = { 0 };
+	struct pack_objects_args po_args = PACK_OBJECTS_ARGS_INIT;
+	struct pack_objects_args cruft_po_args = PACK_OBJECTS_ARGS_INIT;
 	int write_midx = 0;
 	const char *cruft_expiration = NULL;
 	const char *expire_to = NULL;
@@ -1567,6 +1567,7 @@ int cmd_repack(int argc,
 
 		cruft_po_args.local = po_args.local;
 		cruft_po_args.quiet = po_args.quiet;
+		cruft_po_args.delta_base_offset = po_args.delta_base_offset;
 
 		ret = write_cruft_pack(&cruft_po_args, packtmp, pack_prefix,
 				       cruft_expiration,
diff --git a/repack.h b/repack.h
index 421d439d5a..12632d7fec 100644
--- a/repack.h
+++ b/repack.h
@@ -15,9 +15,12 @@ struct pack_objects_args {
 	int local;
 	int name_hash_version;
 	int path_walk;
+	int delta_base_offset;
 	struct list_objects_filter_options filter_options;
 };
 
+#define PACK_OBJECTS_ARGS_INIT { .delta_base_offset = 1 }
+
 void pack_objects_args_release(struct pack_objects_args *args);
 
 #endif /* REPACK_H */

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index f4af830353..ff93654cfe 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -288,40 +288,6 @@ static void collect_pack_filenames(struct existing_packs *existing,
 	strbuf_release(&buf);
 }
 
-static void prepare_pack_objects(struct child_process *cmd,
-				 const struct pack_objects_args *args,
-				 const char *out)
-{
-	strvec_push(&cmd->args, "pack-objects");
-	if (args->window)
-		strvec_pushf(&cmd->args, "--window=%s", args->window);
-	if (args->window_memory)
-		strvec_pushf(&cmd->args, "--window-memory=%s", args->window_memory);
-	if (args->depth)
-		strvec_pushf(&cmd->args, "--depth=%s", args->depth);
-	if (args->threads)
-		strvec_pushf(&cmd->args, "--threads=%s", args->threads);
-	if (args->max_pack_size)
-		strvec_pushf(&cmd->args, "--max-pack-size=%lu", args->max_pack_size);
-	if (args->no_reuse_delta)
-		strvec_pushf(&cmd->args, "--no-reuse-delta");
-	if (args->no_reuse_object)
-		strvec_pushf(&cmd->args, "--no-reuse-object");
-	if (args->name_hash_version)
-		strvec_pushf(&cmd->args, "--name-hash-version=%d", args->name_hash_version);
-	if (args->path_walk)
-		strvec_pushf(&cmd->args, "--path-walk");
-	if (args->local)
-		strvec_push(&cmd->args,  "--local");
-	if (args->quiet)
-		strvec_push(&cmd->args,  "--quiet");
-	if (args->delta_base_offset)
-		strvec_push(&cmd->args,  "--delta-base-offset");
-	strvec_push(&cmd->args, out);
-	cmd->git_cmd = 1;
-	cmd->out = -1;
-}
-
 struct write_oid_context {
 	struct child_process *cmd;
 	const struct git_hash_algo *algop;
diff --git a/repack.c b/repack.c
index a1f5b796fb..91b6e1cc09 100644
--- a/repack.c
+++ b/repack.c
@@ -1,5 +1,40 @@
 #include "git-compat-util.h"
 #include "repack.h"
+#include "run-command.h"
+
+void prepare_pack_objects(struct child_process *cmd,
+			  const struct pack_objects_args *args,
+			  const char *out)
+{
+	strvec_push(&cmd->args, "pack-objects");
+	if (args->window)
+		strvec_pushf(&cmd->args, "--window=%s", args->window);
+	if (args->window_memory)
+		strvec_pushf(&cmd->args, "--window-memory=%s", args->window_memory);
+	if (args->depth)
+		strvec_pushf(&cmd->args, "--depth=%s", args->depth);
+	if (args->threads)
+		strvec_pushf(&cmd->args, "--threads=%s", args->threads);
+	if (args->max_pack_size)
+		strvec_pushf(&cmd->args, "--max-pack-size=%lu", args->max_pack_size);
+	if (args->no_reuse_delta)
+		strvec_pushf(&cmd->args, "--no-reuse-delta");
+	if (args->no_reuse_object)
+		strvec_pushf(&cmd->args, "--no-reuse-object");
+	if (args->name_hash_version)
+		strvec_pushf(&cmd->args, "--name-hash-version=%d", args->name_hash_version);
+	if (args->path_walk)
+		strvec_pushf(&cmd->args, "--path-walk");
+	if (args->local)
+		strvec_push(&cmd->args,  "--local");
+	if (args->quiet)
+		strvec_push(&cmd->args,  "--quiet");
+	if (args->delta_base_offset)
+		strvec_push(&cmd->args,  "--delta-base-offset");
+	strvec_push(&cmd->args, out);
+	cmd->git_cmd = 1;
+	cmd->out = -1;
+}
 
 void pack_objects_args_release(struct pack_objects_args *args)
 {
diff --git a/repack.h b/repack.h
index 12632d7fec..3f7ec20735 100644
--- a/repack.h
+++ b/repack.h
@@ -21,6 +21,11 @@ struct pack_objects_args {
 
 #define PACK_OBJECTS_ARGS_INIT { .delta_base_offset = 1 }
 
+struct child_process;
+
+void prepare_pack_objects(struct child_process *cmd,
+			  const struct pack_objects_args *args,
+			  const char *out);
 void pack_objects_args_release(struct pack_objects_args *args);
 
 #endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index ff93654cfe..f82e6c3930 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -121,39 +121,39 @@ struct existing_packs {
 	.cruft_packs = STRING_LIST_INIT_DUP, \
 }
 
-static int has_existing_non_kept_packs(const struct existing_packs *existing)
+static int existing_packs_has_non_kept(const struct existing_packs *existing)
 {
 	return existing->non_kept_packs.nr || existing->cruft_packs.nr;
 }
 
-static void pack_mark_for_deletion(struct string_list_item *item)
+static void existing_pack_mark_for_deletion(struct string_list_item *item)
 {
 	item->util = (void*)((uintptr_t)item->util | DELETE_PACK);
 }
 
-static void pack_unmark_for_deletion(struct string_list_item *item)
+static void existing_pack_unmark_for_deletion(struct string_list_item *item)
 {
 	item->util = (void*)((uintptr_t)item->util & ~DELETE_PACK);
 }
 
-static int pack_is_marked_for_deletion(struct string_list_item *item)
+static int existing_pack_is_marked_for_deletion(struct string_list_item *item)
 {
 	return (uintptr_t)item->util & DELETE_PACK;
 }
 
-static void pack_mark_retained(struct string_list_item *item)
+static void existing_packs_mark_retained(struct string_list_item *item)
 {
 	item->util = (void*)((uintptr_t)item->util | RETAIN_PACK);
 }
 
-static int pack_is_retained(struct string_list_item *item)
+static int existing_pack_is_retained(struct string_list_item *item)
 {
 	return (uintptr_t)item->util & RETAIN_PACK;
 }
 
-static void mark_packs_for_deletion_1(const struct git_hash_algo *algop,
-				      struct string_list *names,
-				      struct string_list *list)
+static void existing_packs_mark_for_deletion_1(const struct git_hash_algo *algop,
+					       struct string_list *names,
+					       struct string_list *list)
 {
 	struct string_list_item *item;
 	const int hexsz = algop->hexsz;
@@ -165,8 +165,8 @@ static void mark_packs_for_deletion_1(const struct git_hash_algo *algop,
 			continue;
 		sha1 = item->string + len - hexsz;
 
-		if (pack_is_retained(item)) {
-			pack_unmark_for_deletion(item);
+		if (existing_pack_is_retained(item)) {
+			existing_pack_unmark_for_deletion(item);
 		} else if (!string_list_has_string(names, sha1)) {
 			/*
 			 * Mark this pack for deletion, which ensures
@@ -175,13 +175,13 @@ static void mark_packs_for_deletion_1(const struct git_hash_algo *algop,
 			 * will actually delete this pack (if `-d` was
 			 * given).
 			 */
-			pack_mark_for_deletion(item);
+			existing_pack_mark_for_deletion(item);
 		}
 	}
 }
 
-static void retain_cruft_pack(struct existing_packs *existing,
-			      struct packed_git *cruft)
+static void existing_packs_retain_cruft(struct existing_packs *existing,
+					struct packed_git *cruft)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct string_list_item *item;
@@ -193,17 +193,19 @@ static void retain_cruft_pack(struct existing_packs *existing,
 	if (!item)
 		BUG("could not find cruft pack '%s'", pack_basename(cruft));
 
-	pack_mark_retained(item);
+	existing_packs_mark_retained(item);
 	strbuf_release(&buf);
 }
 
-static void mark_packs_for_deletion(struct existing_packs *existing,
-				    struct string_list *names)
+static void existing_packs_mark_for_deletion(struct existing_packs *existing,
+					     struct string_list *names)
 
 {
 	const struct git_hash_algo *algop = existing->repo->hash_algo;
-	mark_packs_for_deletion_1(algop, names, &existing->non_kept_packs);
-	mark_packs_for_deletion_1(algop, names, &existing->cruft_packs);
+	existing_packs_mark_for_deletion_1(algop, names,
+					   &existing->non_kept_packs);
+	existing_packs_mark_for_deletion_1(algop, names,
+					   &existing->cruft_packs);
 }
 
 static void remove_redundant_pack(struct repository *repo,
@@ -225,13 +227,13 @@ static void remove_redundant_packs_1(struct repository *repo,
 {
 	struct string_list_item *item;
 	for_each_string_list_item(item, packs) {
-		if (!pack_is_marked_for_deletion(item))
+		if (!existing_pack_is_marked_for_deletion(item))
 			continue;
 		remove_redundant_pack(repo, packdir, item->string);
 	}
 }
 
-static void remove_redundant_existing_packs(struct existing_packs *existing)
+static void existing_packs_remove_redundant(struct existing_packs *existing)
 {
 	remove_redundant_packs_1(existing->repo, &existing->non_kept_packs);
 	remove_redundant_packs_1(existing->repo, &existing->cruft_packs);
@@ -250,7 +252,7 @@ static void existing_packs_release(struct existing_packs *existing)
  * .keep file or not.  Packs without a .keep file are not to be kept
  * if we are going to pack everything into one file.
  */
-static void collect_pack_filenames(struct existing_packs *existing,
+static void existing_packs_collect(struct existing_packs *existing,
 				   const struct string_list *extra_keep)
 {
 	struct packfile_store *packs = existing->repo->objects->packfiles;
@@ -721,7 +723,7 @@ static int midx_has_unknown_packs(char **midx_pack_names,
 
 			item = string_list_lookup(&existing->non_kept_packs,
 						  pack_name);
-			if (item && !pack_is_marked_for_deletion(item))
+			if (item && !existing_pack_is_marked_for_deletion(item))
 				continue;
 		}
 
@@ -851,7 +853,7 @@ static void midx_included_packs(struct string_list *include,
 		}
 	} else {
 		for_each_string_list_item(item, &existing->non_kept_packs) {
-			if (pack_is_marked_for_deletion(item))
+			if (existing_pack_is_marked_for_deletion(item))
 				continue;
 
 			strbuf_reset(&buf);
@@ -888,10 +890,10 @@ static void midx_included_packs(struct string_list *include,
 			 * --geometric case, but doing so is unnecessary
 			 *  since no packs are marked as pending
 			 *  deletion (since we only call
-			 *  `mark_packs_for_deletion()` when doing an
-			 *  all-into-one repack).
+			 *  `existing_packs_mark_for_deletion()` when
+			 *  doing an all-into-one repack).
 			 */
-			if (pack_is_marked_for_deletion(item))
+			if (existing_pack_is_marked_for_deletion(item))
 				continue;
 
 			strbuf_reset(&buf);
@@ -1128,7 +1130,7 @@ static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
 		if (p->pack_size < combine_cruft_below_size) {
 			fprintf(in, "-%s\n", pack_basename(p));
 		} else {
-			retain_cruft_pack(existing, p);
+			existing_packs_retain_cruft(existing, p);
 			fprintf(in, "%s\n", pack_basename(p));
 		}
 	}
@@ -1382,7 +1384,7 @@ int cmd_repack(int argc,
 	packtmp = mkpathdup("%s/%s", packdir, packtmp_name);
 
 	existing.repo = repo;
-	collect_pack_filenames(&existing, &keep_pack_list);
+	existing_packs_collect(&existing, &keep_pack_list);
 
 	if (geometry.split_factor) {
 		if (pack_everything)
@@ -1431,7 +1433,7 @@ int cmd_repack(int argc,
 	if (pack_everything & ALL_INTO_ONE) {
 		repack_promisor_objects(repo, &po_args, &names);
 
-		if (has_existing_non_kept_packs(&existing) &&
+		if (existing_packs_has_non_kept(&existing) &&
 		    delete_redundant &&
 		    !(pack_everything & PACK_CRUFT)) {
 			for_each_string_list_item(item, &names) {
@@ -1647,7 +1649,7 @@ int cmd_repack(int argc,
 	/* End of pack replacement. */
 
 	if (delete_redundant && pack_everything & ALL_INTO_ONE)
-		mark_packs_for_deletion(&existing, &names);
+		existing_packs_mark_for_deletion(&existing, &names);
 
 	if (write_midx) {
 		struct string_list include = STRING_LIST_INIT_DUP;
@@ -1671,7 +1673,7 @@ int cmd_repack(int argc,
 
 	if (delete_redundant) {
 		int opts = 0;
-		remove_redundant_existing_packs(&existing);
+		existing_packs_remove_redundant(&existing);
 
 		if (geometry.split_factor)
 			geometry_remove_redundant_packs(&geometry, &names,

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index f82e6c3930..31137cf711 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -208,20 +208,6 @@ static void existing_packs_mark_for_deletion(struct existing_packs *existing,
 					   &existing->cruft_packs);
 }
 
-static void remove_redundant_pack(struct repository *repo,
-				  const char *dir_name, const char *base_name)
-{
-	struct strbuf buf = STRBUF_INIT;
-	struct odb_source *source = repo->objects->sources;
-	struct multi_pack_index *m = get_multi_pack_index(source);
-	strbuf_addf(&buf, "%s.pack", base_name);
-	if (m && source->local && midx_contains_pack(m, buf.buf))
-		clear_midx_file(repo);
-	strbuf_insertf(&buf, 0, "%s/", dir_name);
-	unlink_pack_path(buf.buf, 1);
-	strbuf_release(&buf);
-}
-
 static void remove_redundant_packs_1(struct repository *repo,
 				     struct string_list *packs)
 {
@@ -229,7 +215,7 @@ static void remove_redundant_packs_1(struct repository *repo,
 	for_each_string_list_item(item, packs) {
 		if (!existing_pack_is_marked_for_deletion(item))
 			continue;
-		remove_redundant_pack(repo, packdir, item->string);
+		repack_remove_redundant_pack(repo, packdir, item->string);
 	}
 }
 
@@ -652,7 +638,7 @@ static void geometry_remove_redundant_packs(struct pack_geometry *geometry,
 		    (string_list_has_string(&existing->kept_packs, buf.buf)))
 			continue;
 
-		remove_redundant_pack(existing->repo, packdir, buf.buf);
+		repack_remove_redundant_pack(existing->repo, packdir, buf.buf);
 	}
 
 	strbuf_release(&buf);
diff --git a/repack.c b/repack.c
index 91b6e1cc09..3aaa351b5b 100644
--- a/repack.c
+++ b/repack.c
@@ -1,5 +1,9 @@
 #include "git-compat-util.h"
+#include "midx.h"
+#include "odb.h"
+#include "packfile.h"
 #include "repack.h"
+#include "repository.h"
 #include "run-command.h"
 
 void prepare_pack_objects(struct child_process *cmd,
@@ -44,3 +48,17 @@ void pack_objects_args_release(struct pack_objects_args *args)
 	free(args->threads);
 	list_objects_filter_release(&args->filter_options);
 }
+
+void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
+				  const char *base_name)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct odb_source *source = repo->objects->sources;
+	struct multi_pack_index *m = get_multi_pack_index(source);
+	strbuf_addf(&buf, "%s.pack", base_name);
+	if (m && source->local && midx_contains_pack(m, buf.buf))
+		clear_midx_file(repo);
+	strbuf_insertf(&buf, 0, "%s/", dir_name);
+	unlink_pack_path(buf.buf, 1);
+	strbuf_release(&buf);
+}
diff --git a/repack.h b/repack.h
index 3f7ec20735..a62bfa2ff9 100644
--- a/repack.h
+++ b/repack.h
@@ -28,4 +28,7 @@ void prepare_pack_objects(struct child_process *cmd,
 			  const char *out);
 void pack_objects_args_release(struct pack_objects_args *args);
 
+void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
+				  const char *base_name);
+
 #endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index 31137cf711..c5a88eda12 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -209,7 +209,8 @@ static void existing_packs_mark_for_deletion(struct existing_packs *existing,
 }
 
 static void remove_redundant_packs_1(struct repository *repo,
-				     struct string_list *packs)
+				     struct string_list *packs,
+				     const char *packdir)
 {
 	struct string_list_item *item;
 	for_each_string_list_item(item, packs) {
@@ -219,10 +220,13 @@ static void remove_redundant_packs_1(struct repository *repo,
 	}
 }
 
-static void existing_packs_remove_redundant(struct existing_packs *existing)
+static void existing_packs_remove_redundant(struct existing_packs *existing,
+					    const char *packdir)
 {
-	remove_redundant_packs_1(existing->repo, &existing->non_kept_packs);
-	remove_redundant_packs_1(existing->repo, &existing->cruft_packs);
+	remove_redundant_packs_1(existing->repo, &existing->non_kept_packs,
+				 packdir);
+	remove_redundant_packs_1(existing->repo, &existing->cruft_packs,
+				 packdir);
 }
 
 static void existing_packs_release(struct existing_packs *existing)
@@ -1659,7 +1663,7 @@ int cmd_repack(int argc,
 
 	if (delete_redundant) {
 		int opts = 0;
-		existing_packs_remove_redundant(&existing);
+		existing_packs_remove_redundant(&existing, packdir);
 
 		if (geometry.split_factor)
 			geometry_remove_redundant_packs(&geometry, &names,

diff --git a/builtin/repack.c b/builtin/repack.c
index ad60c4290d..565538bb24 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -27,7 +27,6 @@ static int pack_everything;
 static int write_bitmaps = -1;
 static int use_delta_islands;
 static int run_update_server_info = 1;
-static char *packdir, *packtmp_name, *packtmp;
 static int midx_must_contain_cruft = 1;

 static const char *const git_repack_usage[] = {
@@ -111,6 +110,7 @@ int cmd_repack(int argc,
 	struct write_pack_opts opts = { 0 };
 	int i, ret;
 	int show_progress;
+	char *packdir, *packtmp_name, *packtmp;

 	/* variables to be filled by option parsing */
 	struct repack_config_ctx config_ctx;
--- >8 ---

But I'd like to err on the side of post-merge followups here to avoid
dumping 49+ more patches on the list. Of course, if there are
showstoppers or other objections, I can easily reroll the series, but
I'd rather avoid doing so on a series this long.

Thanks,
Taylor

diff --git a/builtin/repack.c b/builtin/repack.c
index c5a88eda12..e13943b637 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -156,7 +156,7 @@ static void existing_packs_mark_for_deletion_1(const struct git_hash_algo *algop
 					       struct string_list *list)
 {
 	struct string_list_item *item;
-	const int hexsz = algop->hexsz;
+	const size_t hexsz = algop->hexsz;
 
 	for_each_string_list_item(item, list) {
 		char *sha1;
@@ -250,7 +250,7 @@ static void existing_packs_collect(struct existing_packs *existing,
 	struct strbuf buf = STRBUF_INIT;
 
 	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
-		int i;
+		size_t i;
 		const char *base;
 
 		if (!p->pack_local)

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index e13943b637..a168c88791 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -3,7 +3,6 @@
 
 #include "builtin.h"
 #include "config.h"
-#include "dir.h"
 #include "environment.h"
 #include "gettext.h"
 #include "hex.h"
@@ -108,178 +107,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-struct existing_packs {
-	struct repository *repo;
-	struct string_list kept_packs;
-	struct string_list non_kept_packs;
-	struct string_list cruft_packs;
-};
-
-#define EXISTING_PACKS_INIT { \
-	.kept_packs = STRING_LIST_INIT_DUP, \
-	.non_kept_packs = STRING_LIST_INIT_DUP, \
-	.cruft_packs = STRING_LIST_INIT_DUP, \
-}
-
-static int existing_packs_has_non_kept(const struct existing_packs *existing)
-{
-	return existing->non_kept_packs.nr || existing->cruft_packs.nr;
-}
-
-static void existing_pack_mark_for_deletion(struct string_list_item *item)
-{
-	item->util = (void*)((uintptr_t)item->util | DELETE_PACK);
-}
-
-static void existing_pack_unmark_for_deletion(struct string_list_item *item)
-{
-	item->util = (void*)((uintptr_t)item->util & ~DELETE_PACK);
-}
-
-static int existing_pack_is_marked_for_deletion(struct string_list_item *item)
-{
-	return (uintptr_t)item->util & DELETE_PACK;
-}
-
-static void existing_packs_mark_retained(struct string_list_item *item)
-{
-	item->util = (void*)((uintptr_t)item->util | RETAIN_PACK);
-}
-
-static int existing_pack_is_retained(struct string_list_item *item)
-{
-	return (uintptr_t)item->util & RETAIN_PACK;
-}
-
-static void existing_packs_mark_for_deletion_1(const struct git_hash_algo *algop,
-					       struct string_list *names,
-					       struct string_list *list)
-{
-	struct string_list_item *item;
-	const size_t hexsz = algop->hexsz;
-
-	for_each_string_list_item(item, list) {
-		char *sha1;
-		size_t len = strlen(item->string);
-		if (len < hexsz)
-			continue;
-		sha1 = item->string + len - hexsz;
-
-		if (existing_pack_is_retained(item)) {
-			existing_pack_unmark_for_deletion(item);
-		} else if (!string_list_has_string(names, sha1)) {
-			/*
-			 * Mark this pack for deletion, which ensures
-			 * that this pack won't be included in a MIDX
-			 * (if `--write-midx` was given) and that we
-			 * will actually delete this pack (if `-d` was
-			 * given).
-			 */
-			existing_pack_mark_for_deletion(item);
-		}
-	}
-}
-
-static void existing_packs_retain_cruft(struct existing_packs *existing,
-					struct packed_git *cruft)
-{
-	struct strbuf buf = STRBUF_INIT;
-	struct string_list_item *item;
-
-	strbuf_addstr(&buf, pack_basename(cruft));
-	strbuf_strip_suffix(&buf, ".pack");
-
-	item = string_list_lookup(&existing->cruft_packs, buf.buf);
-	if (!item)
-		BUG("could not find cruft pack '%s'", pack_basename(cruft));
-
-	existing_packs_mark_retained(item);
-	strbuf_release(&buf);
-}
-
-static void existing_packs_mark_for_deletion(struct existing_packs *existing,
-					     struct string_list *names)
-
-{
-	const struct git_hash_algo *algop = existing->repo->hash_algo;
-	existing_packs_mark_for_deletion_1(algop, names,
-					   &existing->non_kept_packs);
-	existing_packs_mark_for_deletion_1(algop, names,
-					   &existing->cruft_packs);
-}
-
-static void remove_redundant_packs_1(struct repository *repo,
-				     struct string_list *packs,
-				     const char *packdir)
-{
-	struct string_list_item *item;
-	for_each_string_list_item(item, packs) {
-		if (!existing_pack_is_marked_for_deletion(item))
-			continue;
-		repack_remove_redundant_pack(repo, packdir, item->string);
-	}
-}
-
-static void existing_packs_remove_redundant(struct existing_packs *existing,
-					    const char *packdir)
-{
-	remove_redundant_packs_1(existing->repo, &existing->non_kept_packs,
-				 packdir);
-	remove_redundant_packs_1(existing->repo, &existing->cruft_packs,
-				 packdir);
-}
-
-static void existing_packs_release(struct existing_packs *existing)
-{
-	string_list_clear(&existing->kept_packs, 0);
-	string_list_clear(&existing->non_kept_packs, 0);
-	string_list_clear(&existing->cruft_packs, 0);
-}
-
-/*
- * Adds all packs hex strings (pack-$HASH) to either packs->non_kept
- * or packs->kept based on whether each pack has a corresponding
- * .keep file or not.  Packs without a .keep file are not to be kept
- * if we are going to pack everything into one file.
- */
-static void existing_packs_collect(struct existing_packs *existing,
-				   const struct string_list *extra_keep)
-{
-	struct packfile_store *packs = existing->repo->objects->packfiles;
-	struct packed_git *p;
-	struct strbuf buf = STRBUF_INIT;
-
-	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
-		size_t i;
-		const char *base;
-
-		if (!p->pack_local)
-			continue;
-
-		base = pack_basename(p);
-
-		for (i = 0; i < extra_keep->nr; i++)
-			if (!fspathcmp(base, extra_keep->items[i].string))
-				break;
-
-		strbuf_reset(&buf);
-		strbuf_addstr(&buf, base);
-		strbuf_strip_suffix(&buf, ".pack");
-
-		if ((extra_keep->nr > 0 && i < extra_keep->nr) || p->pack_keep)
-			string_list_append(&existing->kept_packs, buf.buf);
-		else if (p->is_cruft)
-			string_list_append(&existing->cruft_packs, buf.buf);
-		else
-			string_list_append(&existing->non_kept_packs, buf.buf);
-	}
-
-	string_list_sort(&existing->kept_packs);
-	string_list_sort(&existing->non_kept_packs);
-	string_list_sort(&existing->cruft_packs);
-	strbuf_release(&buf);
-}
-
 struct write_oid_context {
 	struct child_process *cmd;
 	const struct git_hash_algo *algop;
diff --git a/repack.c b/repack.c
index 3aaa351b5b..9182e1c50b 100644
--- a/repack.c
+++ b/repack.c
@@ -1,4 +1,5 @@
 #include "git-compat-util.h"
+#include "dir.h"
 #include "midx.h"
 #include "odb.h"
 #include "packfile.h"
@@ -62,3 +63,159 @@ void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
 	unlink_pack_path(buf.buf, 1);
 	strbuf_release(&buf);
 }
+
+#define DELETE_PACK 1
+#define RETAIN_PACK 2
+
+void existing_packs_collect(struct existing_packs *existing,
+			    const struct string_list *extra_keep)
+{
+	struct packfile_store *packs = existing->repo->objects->packfiles;
+	struct packed_git *p;
+	struct strbuf buf = STRBUF_INIT;
+
+	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
+		size_t i;
+		const char *base;
+
+		if (!p->pack_local)
+			continue;
+
+		base = pack_basename(p);
+
+		for (i = 0; i < extra_keep->nr; i++)
+			if (!fspathcmp(base, extra_keep->items[i].string))
+				break;
+
+		strbuf_reset(&buf);
+		strbuf_addstr(&buf, base);
+		strbuf_strip_suffix(&buf, ".pack");
+
+		if ((extra_keep->nr > 0 && i < extra_keep->nr) || p->pack_keep)
+			string_list_append(&existing->kept_packs, buf.buf);
+		else if (p->is_cruft)
+			string_list_append(&existing->cruft_packs, buf.buf);
+		else
+			string_list_append(&existing->non_kept_packs, buf.buf);
+	}
+
+	string_list_sort(&existing->kept_packs);
+	string_list_sort(&existing->non_kept_packs);
+	string_list_sort(&existing->cruft_packs);
+	strbuf_release(&buf);
+}
+
+int existing_packs_has_non_kept(const struct existing_packs *existing)
+{
+	return existing->non_kept_packs.nr || existing->cruft_packs.nr;
+}
+
+static void existing_pack_mark_for_deletion(struct string_list_item *item)
+{
+	item->util = (void*)((uintptr_t)item->util | DELETE_PACK);
+}
+
+static void existing_pack_unmark_for_deletion(struct string_list_item *item)
+{
+	item->util = (void*)((uintptr_t)item->util & ~DELETE_PACK);
+}
+
+int existing_pack_is_marked_for_deletion(struct string_list_item *item)
+{
+	return (uintptr_t)item->util & DELETE_PACK;
+}
+
+static void existing_packs_mark_retained(struct string_list_item *item)
+{
+	item->util = (void*)((uintptr_t)item->util | RETAIN_PACK);
+}
+
+static int existing_pack_is_retained(struct string_list_item *item)
+{
+	return (uintptr_t)item->util & RETAIN_PACK;
+}
+
+static void existing_packs_mark_for_deletion_1(const struct git_hash_algo *algop,
+					       struct string_list *names,
+					       struct string_list *list)
+{
+	struct string_list_item *item;
+	const size_t hexsz = algop->hexsz;
+
+	for_each_string_list_item(item, list) {
+		char *sha1;
+		size_t len = strlen(item->string);
+		if (len < hexsz)
+			continue;
+		sha1 = item->string + len - hexsz;
+
+		if (existing_pack_is_retained(item)) {
+			existing_pack_unmark_for_deletion(item);
+		} else if (!string_list_has_string(names, sha1)) {
+			/*
+			 * Mark this pack for deletion, which ensures
+			 * that this pack won't be included in a MIDX
+			 * (if `--write-midx` was given) and that we
+			 * will actually delete this pack (if `-d` was
+			 * given).
+			 */
+			existing_pack_mark_for_deletion(item);
+		}
+	}
+}
+
+void existing_packs_retain_cruft(struct existing_packs *existing,
+				 struct packed_git *cruft)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct string_list_item *item;
+
+	strbuf_addstr(&buf, pack_basename(cruft));
+	strbuf_strip_suffix(&buf, ".pack");
+
+	item = string_list_lookup(&existing->cruft_packs, buf.buf);
+	if (!item)
+		BUG("could not find cruft pack '%s'", pack_basename(cruft));
+
+	existing_packs_mark_retained(item);
+	strbuf_release(&buf);
+}
+
+void existing_packs_mark_for_deletion(struct existing_packs *existing,
+				      struct string_list *names)
+
+{
+	const struct git_hash_algo *algop = existing->repo->hash_algo;
+	existing_packs_mark_for_deletion_1(algop, names,
+					   &existing->non_kept_packs);
+	existing_packs_mark_for_deletion_1(algop, names,
+					   &existing->cruft_packs);
+}
+
+static void remove_redundant_packs_1(struct repository *repo,
+				     struct string_list *packs,
+				     const char *packdir)
+{
+	struct string_list_item *item;
+	for_each_string_list_item(item, packs) {
+		if (!existing_pack_is_marked_for_deletion(item))
+			continue;
+		repack_remove_redundant_pack(repo, packdir, item->string);
+	}
+}
+
+void existing_packs_remove_redundant(struct existing_packs *existing,
+				     const char *packdir)
+{
+	remove_redundant_packs_1(existing->repo, &existing->non_kept_packs,
+				 packdir);
+	remove_redundant_packs_1(existing->repo, &existing->cruft_packs,
+				 packdir);
+}
+
+void existing_packs_release(struct existing_packs *existing)
+{
+	string_list_clear(&existing->kept_packs, 0);
+	string_list_clear(&existing->non_kept_packs, 0);
+	string_list_clear(&existing->cruft_packs, 0);
+}
diff --git a/repack.h b/repack.h
index a62bfa2ff9..19796e2243 100644
--- a/repack.h
+++ b/repack.h
@@ -2,6 +2,7 @@
 #define REPACK_H
 
 #include "list-objects-filter-options.h"
+#include "string-list.h"
 
 struct pack_objects_args {
 	char *window;
@@ -31,4 +32,38 @@ void pack_objects_args_release(struct pack_objects_args *args);
 void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
 				  const char *base_name);
 
+struct repository;
+struct packed_git;
+
+struct existing_packs {
+	struct repository *repo;
+	struct string_list kept_packs;
+	struct string_list non_kept_packs;
+	struct string_list cruft_packs;
+};
+
+#define EXISTING_PACKS_INIT { \
+	.kept_packs = STRING_LIST_INIT_DUP, \
+	.non_kept_packs = STRING_LIST_INIT_DUP, \
+	.cruft_packs = STRING_LIST_INIT_DUP, \
+}
+
+/*
+ * Adds all packs hex strings (pack-$HASH) to either packs->non_kept
+ * or packs->kept based on whether each pack has a corresponding
+ * .keep file or not.  Packs without a .keep file are not to be kept
+ * if we are going to pack everything into one file.
+ */
+void existing_packs_collect(struct existing_packs *existing,
+			    const struct string_list *extra_keep);
+int existing_packs_has_non_kept(const struct existing_packs *existing);
+int existing_pack_is_marked_for_deletion(struct string_list_item *item);
+void existing_packs_retain_cruft(struct existing_packs *existing,
+				 struct packed_git *cruft);
+void existing_packs_mark_for_deletion(struct existing_packs *existing,
+				      struct string_list *names);
+void existing_packs_remove_redundant(struct existing_packs *existing,
+				     const char *packdir);
+void existing_packs_release(struct existing_packs *existing);
+
 #endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index a168c88791..a4d80b6b04 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -146,15 +146,15 @@ static struct {
 	{".idx"},
 };
 
-struct generated_pack_data {
+struct generated_pack {
 	struct tempfile *tempfiles[ARRAY_SIZE(exts)];
 };
 
-static struct generated_pack_data *populate_pack_exts(const char *name)
+static struct generated_pack *generated_pack_populate(const char *name)
 {
 	struct stat statbuf;
 	struct strbuf path = STRBUF_INIT;
-	struct generated_pack_data *data = xcalloc(1, sizeof(*data));
+	struct generated_pack *pack = xcalloc(1, sizeof(*pack));
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(exts); i++) {
@@ -164,21 +164,21 @@ static struct generated_pack_data *populate_pack_exts(const char *name)
 		if (stat(path.buf, &statbuf))
 			continue;
 
-		data->tempfiles[i] = register_tempfile(path.buf);
+		pack->tempfiles[i] = register_tempfile(path.buf);
 	}
 
 	strbuf_release(&path);
-	return data;
+	return pack;
 }
 
-static int has_pack_ext(const struct generated_pack_data *data,
-			const char *ext)
+static int generated_pack_has_ext(const struct generated_pack *pack,
+				  const char *ext)
 {
 	int i;
 	for (i = 0; i < ARRAY_SIZE(exts); i++) {
 		if (strcmp(exts[i].name, ext))
 			continue;
-		return !!data->tempfiles[i];
+		return !!pack->tempfiles[i];
 	}
 	BUG("unknown pack extension: '%s'", ext);
 }
@@ -239,7 +239,7 @@ static void repack_promisor_objects(struct repository *repo,
 					  line.buf);
 		write_promisor_file(promisor_name, NULL, 0);
 
-		item->util = populate_pack_exts(item->string);
+		item->util = generated_pack_populate(item->string);
 
 		free(promisor_name);
 	}
@@ -780,8 +780,8 @@ static int write_midx_included_packs(struct string_list *include,
 		 * will suffice, so pick the first one.)
 		 */
 		for_each_string_list_item(item, names) {
-			struct generated_pack_data *data = item->util;
-			if (has_pack_ext(data, ".mtimes"))
+			struct generated_pack *pack = item->util;
+			if (generated_pack_has_ext(pack, ".mtimes"))
 				continue;
 
 			strvec_pushf(&cmd.args, "--preferred-pack=pack-%s.pack",
@@ -864,7 +864,7 @@ static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
 		 */
 		if (local) {
 			item = string_list_append(names, line.buf);
-			item->util = populate_pack_exts(line.buf);
+			item->util = generated_pack_populate(line.buf);
 		}
 	}
 	fclose(out);
@@ -1435,7 +1435,7 @@ int cmd_repack(int argc,
 	 * Ok we have prepared all new packfiles.
 	 */
 	for_each_string_list_item(item, &names) {
-		struct generated_pack_data *data = item->util;
+		struct generated_pack *pack = item->util;
 
 		for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
 			char *fname;
@@ -1443,8 +1443,8 @@ int cmd_repack(int argc,
 			fname = mkpathdup("%s/pack-%s%s",
 					packdir, item->string, exts[ext].name);
 
-			if (data->tempfiles[ext]) {
-				const char *fname_old = get_tempfile_path(data->tempfiles[ext]);
+			if (pack->tempfiles[ext]) {
+				const char *fname_old = get_tempfile_path(pack->tempfiles[ext]);
 				struct stat statbuffer;
 
 				if (!stat(fname_old, &statbuffer)) {
@@ -1452,7 +1452,7 @@ int cmd_repack(int argc,
 					chmod(fname_old, statbuffer.st_mode);
 				}
 
-				if (rename_tempfile(&data->tempfiles[ext], fname))
+				if (rename_tempfile(&pack->tempfiles[ext], fname))
 					die_errno(_("renaming pack to '%s' failed"), fname);
 			} else if (!exts[ext].optional)
 				die(_("pack-objects did not write a '%s' file for pack %s-%s"),

diff --git a/builtin/repack.c b/builtin/repack.c
index a4d80b6b04..8c3a5f4f80 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -183,6 +183,38 @@ static int generated_pack_has_ext(const struct generated_pack *pack,
 	BUG("unknown pack extension: '%s'", ext);
 }
 
+static void generated_pack_install(struct generated_pack *pack,
+				   const char *name)
+{
+	int ext;
+	for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
+		char *fname;
+
+		fname = mkpathdup("%s/pack-%s%s", packdir, name,
+				  exts[ext].name);
+
+		if (pack->tempfiles[ext]) {
+			const char *fname_old = get_tempfile_path(pack->tempfiles[ext]);
+			struct stat statbuffer;
+
+			if (!stat(fname_old, &statbuffer)) {
+				statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
+				chmod(fname_old, statbuffer.st_mode);
+			}
+
+			if (rename_tempfile(&pack->tempfiles[ext], fname))
+				die_errno(_("renaming pack to '%s' failed"),
+					  fname);
+		} else if (!exts[ext].optional)
+			die(_("pack-objects did not write a '%s' file for pack %s-%s"),
+			    exts[ext].name, packtmp, name);
+		else if (unlink(fname) < 0 && errno != ENOENT)
+			die_errno(_("could not unlink: %s"), fname);
+
+		free(fname);
+	}
+}
+
 static void repack_promisor_objects(struct repository *repo,
 				    const struct pack_objects_args *args,
 				    struct string_list *names)
@@ -1045,7 +1077,7 @@ int cmd_repack(int argc,
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
 	struct tempfile *refs_snapshot = NULL;
-	int i, ext, ret;
+	int i, ret;
 	int show_progress;
 	char **midx_pack_names = NULL;
 	size_t midx_pack_names_nr = 0;
@@ -1434,35 +1466,9 @@ int cmd_repack(int argc,
 	/*
 	 * Ok we have prepared all new packfiles.
 	 */
-	for_each_string_list_item(item, &names) {
-		struct generated_pack *pack = item->util;
-
-		for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
-			char *fname;
-
-			fname = mkpathdup("%s/pack-%s%s",
-					packdir, item->string, exts[ext].name);
-
-			if (pack->tempfiles[ext]) {
-				const char *fname_old = get_tempfile_path(pack->tempfiles[ext]);
-				struct stat statbuffer;
-
-				if (!stat(fname_old, &statbuffer)) {
-					statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
-					chmod(fname_old, statbuffer.st_mode);
-				}
-
-				if (rename_tempfile(&pack->tempfiles[ext], fname))
-					die_errno(_("renaming pack to '%s' failed"), fname);
-			} else if (!exts[ext].optional)
-				die(_("pack-objects did not write a '%s' file for pack %s-%s"),
-				    exts[ext].name, packtmp, item->string);
-			else if (unlink(fname) < 0 && errno != ENOENT)
-				die_errno(_("could not unlink: %s"), fname);
-
-			free(fname);
-		}
-	}
+	for_each_string_list_item(item, &names)
+		generated_pack_install((struct generated_pack *)item->util,
+				       item->string);
 	/* End of pack replacement. */
 
 	if (delete_redundant && pack_everything & ALL_INTO_ONE)

diff --git a/builtin/repack.c b/builtin/repack.c
index 8c3a5f4f80..2141c43bd2 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -150,7 +150,8 @@ struct generated_pack {
 	struct tempfile *tempfiles[ARRAY_SIZE(exts)];
 };
 
-static struct generated_pack *generated_pack_populate(const char *name)
+static struct generated_pack *generated_pack_populate(const char *name,
+						      const char *packtmp)
 {
 	struct stat statbuf;
 	struct strbuf path = STRBUF_INIT;
@@ -271,7 +272,7 @@ static void repack_promisor_objects(struct repository *repo,
 					  line.buf);
 		write_promisor_file(promisor_name, NULL, 0);
 
-		item->util = generated_pack_populate(item->string);
+		item->util = generated_pack_populate(item->string, packtmp);
 
 		free(promisor_name);
 	}
@@ -896,7 +897,7 @@ static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
 		 */
 		if (local) {
 			item = string_list_append(names, line.buf);
-			item->util = generated_pack_populate(line.buf);
+			item->util = generated_pack_populate(line.buf, packtmp);
 		}
 	}
 	fclose(out);

diff --git a/builtin/repack.c b/builtin/repack.c
index 2141c43bd2..a4f0a19453 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -185,7 +185,8 @@ static int generated_pack_has_ext(const struct generated_pack *pack,
 }
 
 static void generated_pack_install(struct generated_pack *pack,
-				   const char *name)
+				   const char *name,
+				   const char *packdir, const char *packtmp)
 {
 	int ext;
 	for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
@@ -1469,7 +1470,7 @@ int cmd_repack(int argc,
 	 */
 	for_each_string_list_item(item, &names)
 		generated_pack_install((struct generated_pack *)item->util,
-				       item->string);
+				       item->string, packdir, packtmp);
 	/* End of pack replacement. */
 
 	if (delete_redundant && pack_everything & ALL_INTO_ONE)

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index a4f0a19453..b7826e676b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -134,89 +134,6 @@ static int write_oid(const struct object_id *oid,
 	return 0;
 }
 
-static struct {
-	const char *name;
-	unsigned optional:1;
-} exts[] = {
-	{".pack"},
-	{".rev", 1},
-	{".mtimes", 1},
-	{".bitmap", 1},
-	{".promisor", 1},
-	{".idx"},
-};
-
-struct generated_pack {
-	struct tempfile *tempfiles[ARRAY_SIZE(exts)];
-};
-
-static struct generated_pack *generated_pack_populate(const char *name,
-						      const char *packtmp)
-{
-	struct stat statbuf;
-	struct strbuf path = STRBUF_INIT;
-	struct generated_pack *pack = xcalloc(1, sizeof(*pack));
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(exts); i++) {
-		strbuf_reset(&path);
-		strbuf_addf(&path, "%s-%s%s", packtmp, name, exts[i].name);
-
-		if (stat(path.buf, &statbuf))
-			continue;
-
-		pack->tempfiles[i] = register_tempfile(path.buf);
-	}
-
-	strbuf_release(&path);
-	return pack;
-}
-
-static int generated_pack_has_ext(const struct generated_pack *pack,
-				  const char *ext)
-{
-	int i;
-	for (i = 0; i < ARRAY_SIZE(exts); i++) {
-		if (strcmp(exts[i].name, ext))
-			continue;
-		return !!pack->tempfiles[i];
-	}
-	BUG("unknown pack extension: '%s'", ext);
-}
-
-static void generated_pack_install(struct generated_pack *pack,
-				   const char *name,
-				   const char *packdir, const char *packtmp)
-{
-	int ext;
-	for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
-		char *fname;
-
-		fname = mkpathdup("%s/pack-%s%s", packdir, name,
-				  exts[ext].name);
-
-		if (pack->tempfiles[ext]) {
-			const char *fname_old = get_tempfile_path(pack->tempfiles[ext]);
-			struct stat statbuffer;
-
-			if (!stat(fname_old, &statbuffer)) {
-				statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
-				chmod(fname_old, statbuffer.st_mode);
-			}
-
-			if (rename_tempfile(&pack->tempfiles[ext], fname))
-				die_errno(_("renaming pack to '%s' failed"),
-					  fname);
-		} else if (!exts[ext].optional)
-			die(_("pack-objects did not write a '%s' file for pack %s-%s"),
-			    exts[ext].name, packtmp, name);
-		else if (unlink(fname) < 0 && errno != ENOENT)
-			die_errno(_("could not unlink: %s"), fname);
-
-		free(fname);
-	}
-}
-
 static void repack_promisor_objects(struct repository *repo,
 				    const struct pack_objects_args *args,
 				    struct string_list *names)
diff --git a/repack.c b/repack.c
index 9182e1c50b..d8afdd352d 100644
--- a/repack.c
+++ b/repack.c
@@ -3,9 +3,11 @@
 #include "midx.h"
 #include "odb.h"
 #include "packfile.h"
+#include "path.h"
 #include "repack.h"
 #include "repository.h"
 #include "run-command.h"
+#include "tempfile.h"
 
 void prepare_pack_objects(struct child_process *cmd,
 			  const struct pack_objects_args *args,
@@ -219,3 +221,84 @@ void existing_packs_release(struct existing_packs *existing)
 	string_list_clear(&existing->non_kept_packs, 0);
 	string_list_clear(&existing->cruft_packs, 0);
 }
+
+static struct {
+	const char *name;
+	unsigned optional:1;
+} exts[] = {
+	{".pack"},
+	{".rev", 1},
+	{".mtimes", 1},
+	{".bitmap", 1},
+	{".promisor", 1},
+	{".idx"},
+};
+
+struct generated_pack {
+	struct tempfile *tempfiles[ARRAY_SIZE(exts)];
+};
+
+struct generated_pack *generated_pack_populate(const char *name,
+					       const char *packtmp)
+{
+	struct stat statbuf;
+	struct strbuf path = STRBUF_INIT;
+	struct generated_pack *pack = xcalloc(1, sizeof(*pack));
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(exts); i++) {
+		strbuf_reset(&path);
+		strbuf_addf(&path, "%s-%s%s", packtmp, name, exts[i].name);
+
+		if (stat(path.buf, &statbuf))
+			continue;
+
+		pack->tempfiles[i] = register_tempfile(path.buf);
+	}
+
+	strbuf_release(&path);
+	return pack;
+}
+
+int generated_pack_has_ext(const struct generated_pack *pack, const char *ext)
+{
+	size_t i;
+	for (i = 0; i < ARRAY_SIZE(exts); i++) {
+		if (strcmp(exts[i].name, ext))
+			continue;
+		return !!pack->tempfiles[i];
+	}
+	BUG("unknown pack extension: '%s'", ext);
+}
+
+void generated_pack_install(struct generated_pack *pack, const char *name,
+			    const char *packdir, const char *packtmp)
+{
+	size_t ext;
+	for (ext = 0; ext < ARRAY_SIZE(exts); ext++) {
+		char *fname;
+
+		fname = mkpathdup("%s/pack-%s%s", packdir, name,
+				  exts[ext].name);
+
+		if (pack->tempfiles[ext]) {
+			const char *fname_old = get_tempfile_path(pack->tempfiles[ext]);
+			struct stat statbuffer;
+
+			if (!stat(fname_old, &statbuffer)) {
+				statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
+				chmod(fname_old, statbuffer.st_mode);
+			}
+
+			if (rename_tempfile(&pack->tempfiles[ext], fname))
+				die_errno(_("renaming pack to '%s' failed"),
+					  fname);
+		} else if (!exts[ext].optional)
+			die(_("pack-objects did not write a '%s' file for pack %s-%s"),
+			    exts[ext].name, packtmp, name);
+		else if (unlink(fname) < 0 && errno != ENOENT)
+			die_errno(_("could not unlink: %s"), fname);
+
+		free(fname);
+	}
+}
diff --git a/repack.h b/repack.h
index 19796e2243..f37eb49524 100644
--- a/repack.h
+++ b/repack.h
@@ -66,4 +66,12 @@ void existing_packs_remove_redundant(struct existing_packs *existing,
 				     const char *packdir);
 void existing_packs_release(struct existing_packs *existing);
 
+struct generated_pack;
+
+struct generated_pack *generated_pack_populate(const char *name,
+					       const char *packtmp);
+int generated_pack_has_ext(const struct generated_pack *pack, const char *ext);
+void generated_pack_install(struct generated_pack *pack, const char *name,
+			    const char *packdir, const char *packtmp);
+
 #endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index b7826e676b..ca7658e38f 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -136,7 +136,8 @@ static int write_oid(const struct object_id *oid,
 
 static void repack_promisor_objects(struct repository *repo,
 				    const struct pack_objects_args *args,
-				    struct string_list *names)
+				    struct string_list *names,
+				    const char *packtmp)
 {
 	struct write_oid_context ctx;
 	struct child_process cmd = CHILD_PROCESS_INIT;
@@ -1199,7 +1200,7 @@ int cmd_repack(int argc,
 		strvec_push(&cmd.args, "--delta-islands");
 
 	if (pack_everything & ALL_INTO_ONE) {
-		repack_promisor_objects(repo, &po_args, &names);
+		repack_promisor_objects(repo, &po_args, &names, packtmp);
 
 		if (existing_packs_has_non_kept(&existing) &&
 		    delete_redundant &&

Makefile, builtin/repack.c, meson.build, repack-promisor.c, repack.h

diff --git a/Makefile b/Makefile
index b220f0f7d8..0a73f8adaf 100644
--- a/Makefile
+++ b/Makefile
@@ -1137,6 +1137,7 @@ LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
+LIB_OBJS += repack-promisor.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o
 LIB_OBJS += repository.o
diff --git a/builtin/repack.c b/builtin/repack.c
index ca7658e38f..18c3df7200 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -107,101 +107,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-struct write_oid_context {
-	struct child_process *cmd;
-	const struct git_hash_algo *algop;
-};
-
-/*
- * Write oid to the given struct child_process's stdin, starting it first if
- * necessary.
- */
-static int write_oid(const struct object_id *oid,
-		     struct packed_git *pack UNUSED,
-		     uint32_t pos UNUSED, void *data)
-{
-	struct write_oid_context *ctx = data;
-	struct child_process *cmd = ctx->cmd;
-
-	if (cmd->in == -1) {
-		if (start_command(cmd))
-			die(_("could not start pack-objects to repack promisor objects"));
-	}
-
-	if (write_in_full(cmd->in, oid_to_hex(oid), ctx->algop->hexsz) < 0 ||
-	    write_in_full(cmd->in, "\n", 1) < 0)
-		die(_("failed to feed promisor objects to pack-objects"));
-	return 0;
-}
-
-static void repack_promisor_objects(struct repository *repo,
-				    const struct pack_objects_args *args,
-				    struct string_list *names,
-				    const char *packtmp)
-{
-	struct write_oid_context ctx;
-	struct child_process cmd = CHILD_PROCESS_INIT;
-	FILE *out;
-	struct strbuf line = STRBUF_INIT;
-
-	prepare_pack_objects(&cmd, args, packtmp);
-	cmd.in = -1;
-
-	/*
-	 * NEEDSWORK: Giving pack-objects only the OIDs without any ordering
-	 * hints may result in suboptimal deltas in the resulting pack. See if
-	 * the OIDs can be sent with fake paths such that pack-objects can use a
-	 * {type -> existing pack order} ordering when computing deltas instead
-	 * of a {type -> size} ordering, which may produce better deltas.
-	 */
-	ctx.cmd = &cmd;
-	ctx.algop = repo->hash_algo;
-	for_each_packed_object(repo, write_oid, &ctx,
-			       FOR_EACH_OBJECT_PROMISOR_ONLY);
-
-	if (cmd.in == -1) {
-		/* No packed objects; cmd was never started */
-		child_process_clear(&cmd);
-		return;
-	}
-
-	close(cmd.in);
-
-	out = xfdopen(cmd.out, "r");
-	while (strbuf_getline_lf(&line, out) != EOF) {
-		struct string_list_item *item;
-		char *promisor_name;
-
-		if (line.len != repo->hash_algo->hexsz)
-			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
-		item = string_list_append(names, line.buf);
-
-		/*
-		 * pack-objects creates the .pack and .idx files, but not the
-		 * .promisor file. Create the .promisor file, which is empty.
-		 *
-		 * NEEDSWORK: fetch-pack sometimes generates non-empty
-		 * .promisor files containing the ref names and associated
-		 * hashes at the point of generation of the corresponding
-		 * packfile, but this would not preserve their contents. Maybe
-		 * concatenate the contents of all .promisor files instead of
-		 * just creating a new empty file.
-		 */
-		promisor_name = mkpathdup("%s-%s.promisor", packtmp,
-					  line.buf);
-		write_promisor_file(promisor_name, NULL, 0);
-
-		item->util = generated_pack_populate(item->string, packtmp);
-
-		free(promisor_name);
-	}
-
-	fclose(out);
-	if (finish_command(&cmd))
-		die(_("could not finish pack-objects to repack promisor objects"));
-	strbuf_release(&line);
-}
-
 struct pack_geometry {
 	struct packed_git **pack;
 	uint32_t pack_nr, pack_alloc;
diff --git a/meson.build b/meson.build
index 8ab287a2ed..ca5603b456 100644
--- a/meson.build
+++ b/meson.build
@@ -463,6 +463,7 @@ libgit_sources = [
   'reftable/writer.c',
   'remote.c',
   'repack.c',
+  'repack-promisor.c',
   'replace-object.c',
   'repo-settings.c',
   'repository.c',
diff --git a/repack-promisor.c b/repack-promisor.c
new file mode 100644
index 0000000000..8bf42fc715
--- /dev/null
+++ b/repack-promisor.c
@@ -0,0 +1,102 @@
+#include "git-compat-util.h"
+#include "repack.h"
+#include "run-command.h"
+#include "hex.h"
+#include "repository.h"
+#include "packfile.h"
+#include "path.h"
+#include "pack.h"
+
+struct write_oid_context {
+	struct child_process *cmd;
+	const struct git_hash_algo *algop;
+};
+
+/*
+ * Write oid to the given struct child_process's stdin, starting it first if
+ * necessary.
+ */
+static int write_oid(const struct object_id *oid,
+		     struct packed_git *pack UNUSED,
+		     uint32_t pos UNUSED, void *data)
+{
+	struct write_oid_context *ctx = data;
+	struct child_process *cmd = ctx->cmd;
+
+	if (cmd->in == -1) {
+		if (start_command(cmd))
+			die(_("could not start pack-objects to repack promisor objects"));
+	}
+
+	if (write_in_full(cmd->in, oid_to_hex(oid), ctx->algop->hexsz) < 0 ||
+	    write_in_full(cmd->in, "\n", 1) < 0)
+		die(_("failed to feed promisor objects to pack-objects"));
+	return 0;
+}
+
+void repack_promisor_objects(struct repository *repo,
+			     const struct pack_objects_args *args,
+			     struct string_list *names, const char *packtmp)
+{
+	struct write_oid_context ctx;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	FILE *out;
+	struct strbuf line = STRBUF_INIT;
+
+	prepare_pack_objects(&cmd, args, packtmp);
+	cmd.in = -1;
+
+	/*
+	 * NEEDSWORK: Giving pack-objects only the OIDs without any ordering
+	 * hints may result in suboptimal deltas in the resulting pack. See if
+	 * the OIDs can be sent with fake paths such that pack-objects can use a
+	 * {type -> existing pack order} ordering when computing deltas instead
+	 * of a {type -> size} ordering, which may produce better deltas.
+	 */
+	ctx.cmd = &cmd;
+	ctx.algop = repo->hash_algo;
+	for_each_packed_object(repo, write_oid, &ctx,
+			       FOR_EACH_OBJECT_PROMISOR_ONLY);
+
+	if (cmd.in == -1) {
+		/* No packed objects; cmd was never started */
+		child_process_clear(&cmd);
+		return;
+	}
+
+	close(cmd.in);
+
+	out = xfdopen(cmd.out, "r");
+	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+		char *promisor_name;
+
+		if (line.len != repo->hash_algo->hexsz)
+			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
+		item = string_list_append(names, line.buf);
+
+		/*
+		 * pack-objects creates the .pack and .idx files, but not the
+		 * .promisor file. Create the .promisor file, which is empty.
+		 *
+		 * NEEDSWORK: fetch-pack sometimes generates non-empty
+		 * .promisor files containing the ref names and associated
+		 * hashes at the point of generation of the corresponding
+		 * packfile, but this would not preserve their contents. Maybe
+		 * concatenate the contents of all .promisor files instead of
+		 * just creating a new empty file.
+		 */
+		promisor_name = mkpathdup("%s-%s.promisor", packtmp,
+					  line.buf);
+		write_promisor_file(promisor_name, NULL, 0);
+
+		item->util = generated_pack_populate(item->string, packtmp);
+
+		free(promisor_name);
+	}
+
+	fclose(out);
+	if (finish_command(&cmd))
+		die(_("could not finish pack-objects to repack promisor objects"));
+	strbuf_release(&line);
+}
diff --git a/repack.h b/repack.h
index f37eb49524..19dc4fd738 100644
--- a/repack.h
+++ b/repack.h
@@ -74,4 +74,8 @@ int generated_pack_has_ext(const struct generated_pack *pack, const char *ext);
 void generated_pack_install(struct generated_pack *pack, const char *name,
 			    const char *packdir, const char *packtmp);
 
+void repack_promisor_objects(struct repository *repo,
+			     const struct pack_objects_args *args,
+			     struct string_list *names, const char *packtmp);
+
 #endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index 18c3df7200..2ce1ae3364 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -115,17 +115,17 @@ struct pack_geometry {
 	int split_factor;
 };
 
-static uint32_t geometry_pack_weight(struct packed_git *p)
+static uint32_t pack_geometry_weight(struct packed_git *p)
 {
 	if (open_pack_index(p))
 		die(_("cannot open index for %s"), p->pack_name);
 	return p->num_objects;
 }
 
-static int geometry_cmp(const void *va, const void *vb)
+static int pack_geometry_cmp(const void *va, const void *vb)
 {
-	uint32_t aw = geometry_pack_weight(*(struct packed_git **)va),
-		 bw = geometry_pack_weight(*(struct packed_git **)vb);
+	uint32_t aw = pack_geometry_weight(*(struct packed_git **)va),
+		 bw = pack_geometry_weight(*(struct packed_git **)vb);
 
 	if (aw < bw)
 		return -1;
@@ -134,7 +134,7 @@ static int geometry_cmp(const void *va, const void *vb)
 	return 0;
 }
 
-static void init_pack_geometry(struct pack_geometry *geometry,
+static void pack_geometry_init(struct pack_geometry *geometry,
 			       struct existing_packs *existing,
 			       const struct pack_objects_args *args)
 {
@@ -184,11 +184,11 @@ static void init_pack_geometry(struct pack_geometry *geometry,
 		geometry->pack_nr++;
 	}
 
-	QSORT(geometry->pack, geometry->pack_nr, geometry_cmp);
+	QSORT(geometry->pack, geometry->pack_nr, pack_geometry_cmp);
 	strbuf_release(&buf);
 }
 
-static void split_pack_geometry(struct pack_geometry *geometry)
+static void pack_geometry_split(struct pack_geometry *geometry)
 {
 	uint32_t i;
 	uint32_t split;
@@ -208,13 +208,13 @@ static void split_pack_geometry(struct pack_geometry *geometry)
 		struct packed_git *prev = geometry->pack[i - 1];
 
 		if (unsigned_mult_overflows(geometry->split_factor,
-					    geometry_pack_weight(prev)))
+					    pack_geometry_weight(prev)))
 			die(_("pack %s too large to consider in geometric "
 			      "progression"),
 			    prev->pack_name);
 
-		if (geometry_pack_weight(ours) <
-		    geometry->split_factor * geometry_pack_weight(prev))
+		if (pack_geometry_weight(ours) <
+		    geometry->split_factor * pack_geometry_weight(prev))
 			break;
 	}
 
@@ -242,9 +242,9 @@ static void split_pack_geometry(struct pack_geometry *geometry)
 	for (i = 0; i < split; i++) {
 		struct packed_git *p = geometry->pack[i];
 
-		if (unsigned_add_overflows(total_size, geometry_pack_weight(p)))
+		if (unsigned_add_overflows(total_size, pack_geometry_weight(p)))
 			die(_("pack %s too large to roll up"), p->pack_name);
-		total_size += geometry_pack_weight(p);
+		total_size += pack_geometry_weight(p);
 	}
 	for (i = split; i < geometry->pack_nr; i++) {
 		struct packed_git *ours = geometry->pack[i];
@@ -253,15 +253,15 @@ static void split_pack_geometry(struct pack_geometry *geometry)
 					    total_size))
 			die(_("pack %s too large to roll up"), ours->pack_name);
 
-		if (geometry_pack_weight(ours) <
+		if (pack_geometry_weight(ours) <
 		    geometry->split_factor * total_size) {
 			if (unsigned_add_overflows(total_size,
-						   geometry_pack_weight(ours)))
+						   pack_geometry_weight(ours)))
 				die(_("pack %s too large to roll up"),
 				    ours->pack_name);
 
 			split++;
-			total_size += geometry_pack_weight(ours);
+			total_size += pack_geometry_weight(ours);
 		} else
 			break;
 	}
@@ -269,7 +269,7 @@ static void split_pack_geometry(struct pack_geometry *geometry)
 	geometry->split = split;
 }
 
-static struct packed_git *get_preferred_pack(struct pack_geometry *geometry)
+static struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geometry)
 {
 	uint32_t i;
 
@@ -304,9 +304,9 @@ static struct packed_git *get_preferred_pack(struct pack_geometry *geometry)
 	return NULL;
 }
 
-static void geometry_remove_redundant_packs(struct pack_geometry *geometry,
-					    struct string_list *names,
-					    struct existing_packs *existing)
+static void pack_geometry_remove_redundant(struct pack_geometry *geometry,
+					   struct string_list *names,
+					   struct existing_packs *existing)
 {
 	const struct git_hash_algo *algop = existing->repo->hash_algo;
 	struct strbuf buf = STRBUF_INIT;
@@ -332,7 +332,7 @@ static void geometry_remove_redundant_packs(struct pack_geometry *geometry,
 	strbuf_release(&buf);
 }
 
-static void free_pack_geometry(struct pack_geometry *geometry)
+static void pack_geometry_release(struct pack_geometry *geometry)
 {
 	if (!geometry)
 		return;
@@ -599,7 +599,7 @@ static int write_midx_included_packs(struct string_list *include,
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
-	struct packed_git *preferred = get_preferred_pack(geometry);
+	struct packed_git *preferred = pack_geometry_preferred_pack(geometry);
 	FILE *in;
 	int ret;
 
@@ -1063,8 +1063,8 @@ int cmd_repack(int argc,
 	if (geometry.split_factor) {
 		if (pack_everything)
 			die(_("options '%s' and '%s' cannot be used together"), "--geometric", "-A/-a");
-		init_pack_geometry(&geometry, &existing, &po_args);
-		split_pack_geometry(&geometry);
+		pack_geometry_init(&geometry, &existing, &po_args);
+		pack_geometry_split(&geometry);
 	}
 
 	prepare_pack_objects(&cmd, &po_args, packtmp);
@@ -1324,8 +1324,8 @@ int cmd_repack(int argc,
 		existing_packs_remove_redundant(&existing, packdir);
 
 		if (geometry.split_factor)
-			geometry_remove_redundant_packs(&geometry, &names,
-							&existing);
+			pack_geometry_remove_redundant(&geometry, &names,
+						       &existing);
 		if (show_progress)
 			opts |= PRUNE_PACKED_VERBOSE;
 		prune_packed_objects(opts);
@@ -1352,7 +1352,7 @@ int cmd_repack(int argc,
 	string_list_clear(&keep_pack_list, 0);
 	string_list_clear(&names, 1);
 	existing_packs_release(&existing);
-	free_pack_geometry(&geometry);
+	pack_geometry_release(&geometry);
 	for (size_t i = 0; i < midx_pack_names_nr; i++)
 		free(midx_pack_names[i]);
 	free(midx_pack_names);

diff --git a/builtin/repack.c b/builtin/repack.c
index 2ce1ae3364..60dce45556 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -136,7 +136,8 @@ static int pack_geometry_cmp(const void *va, const void *vb)
 
 static void pack_geometry_init(struct pack_geometry *geometry,
 			       struct existing_packs *existing,
-			       const struct pack_objects_args *args)
+			       const struct pack_objects_args *args,
+			       int pack_kept_objects)
 {
 	struct packfile_store *packs = existing->repo->objects->packfiles;
 	struct packed_git *p;
@@ -1063,7 +1064,8 @@ int cmd_repack(int argc,
 	if (geometry.split_factor) {
 		if (pack_everything)
 			die(_("options '%s' and '%s' cannot be used together"), "--geometric", "-A/-a");
-		pack_geometry_init(&geometry, &existing, &po_args);
+		pack_geometry_init(&geometry, &existing, &po_args,
+				   pack_kept_objects);
 		pack_geometry_split(&geometry);
 	}
 

diff --git a/builtin/repack.c b/builtin/repack.c
index 60dce45556..9e2523d948 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -307,7 +307,8 @@ static struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geo
 
 static void pack_geometry_remove_redundant(struct pack_geometry *geometry,
 					   struct string_list *names,
-					   struct existing_packs *existing)
+					   struct existing_packs *existing,
+					   const char *packdir)
 {
 	const struct git_hash_algo *algop = existing->repo->hash_algo;
 	struct strbuf buf = STRBUF_INIT;
@@ -1327,7 +1328,7 @@ int cmd_repack(int argc,
 
 		if (geometry.split_factor)
 			pack_geometry_remove_redundant(&geometry, &names,
-						       &existing);
+						       &existing, packdir);
 		if (show_progress)
 			opts |= PRUNE_PACKED_VERBOSE;
 		prune_packed_objects(opts);

Makefile, builtin/repack.c, meson.build, repack-geometry.c, repack.h

diff --git a/Makefile b/Makefile
index 0a73f8adaf..a6da12a326 100644
--- a/Makefile
+++ b/Makefile
@@ -1137,6 +1137,7 @@ LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
+LIB_OBJS += repack-geometry.o
 LIB_OBJS += repack-promisor.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o
diff --git a/builtin/repack.c b/builtin/repack.c
index 9e2523d948..b49e2dab9a 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -107,241 +107,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-struct pack_geometry {
-	struct packed_git **pack;
-	uint32_t pack_nr, pack_alloc;
-	uint32_t split;
-
-	int split_factor;
-};
-
-static uint32_t pack_geometry_weight(struct packed_git *p)
-{
-	if (open_pack_index(p))
-		die(_("cannot open index for %s"), p->pack_name);
-	return p->num_objects;
-}
-
-static int pack_geometry_cmp(const void *va, const void *vb)
-{
-	uint32_t aw = pack_geometry_weight(*(struct packed_git **)va),
-		 bw = pack_geometry_weight(*(struct packed_git **)vb);
-
-	if (aw < bw)
-		return -1;
-	if (aw > bw)
-		return 1;
-	return 0;
-}
-
-static void pack_geometry_init(struct pack_geometry *geometry,
-			       struct existing_packs *existing,
-			       const struct pack_objects_args *args,
-			       int pack_kept_objects)
-{
-	struct packfile_store *packs = existing->repo->objects->packfiles;
-	struct packed_git *p;
-	struct strbuf buf = STRBUF_INIT;
-
-	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
-		if (args->local && !p->pack_local)
-			/*
-			 * When asked to only repack local packfiles we skip
-			 * over any packfiles that are borrowed from alternate
-			 * object directories.
-			 */
-			continue;
-
-		if (!pack_kept_objects) {
-			/*
-			 * Any pack that has its pack_keep bit set will
-			 * appear in existing->kept_packs below, but
-			 * this saves us from doing a more expensive
-			 * check.
-			 */
-			if (p->pack_keep)
-				continue;
-
-			/*
-			 * The pack may be kept via the --keep-pack
-			 * option; check 'existing->kept_packs' to
-			 * determine whether to ignore it.
-			 */
-			strbuf_reset(&buf);
-			strbuf_addstr(&buf, pack_basename(p));
-			strbuf_strip_suffix(&buf, ".pack");
-
-			if (string_list_has_string(&existing->kept_packs, buf.buf))
-				continue;
-		}
-		if (p->is_cruft)
-			continue;
-
-		ALLOC_GROW(geometry->pack,
-			   geometry->pack_nr + 1,
-			   geometry->pack_alloc);
-
-		geometry->pack[geometry->pack_nr] = p;
-		geometry->pack_nr++;
-	}
-
-	QSORT(geometry->pack, geometry->pack_nr, pack_geometry_cmp);
-	strbuf_release(&buf);
-}
-
-static void pack_geometry_split(struct pack_geometry *geometry)
-{
-	uint32_t i;
-	uint32_t split;
-	off_t total_size = 0;
-
-	if (!geometry->pack_nr) {
-		geometry->split = geometry->pack_nr;
-		return;
-	}
-
-	/*
-	 * First, count the number of packs (in descending order of size) which
-	 * already form a geometric progression.
-	 */
-	for (i = geometry->pack_nr - 1; i > 0; i--) {
-		struct packed_git *ours = geometry->pack[i];
-		struct packed_git *prev = geometry->pack[i - 1];
-
-		if (unsigned_mult_overflows(geometry->split_factor,
-					    pack_geometry_weight(prev)))
-			die(_("pack %s too large to consider in geometric "
-			      "progression"),
-			    prev->pack_name);
-
-		if (pack_geometry_weight(ours) <
-		    geometry->split_factor * pack_geometry_weight(prev))
-			break;
-	}
-
-	split = i;
-
-	if (split) {
-		/*
-		 * Move the split one to the right, since the top element in the
-		 * last-compared pair can't be in the progression. Only do this
-		 * when we split in the middle of the array (otherwise if we got
-		 * to the end, then the split is in the right place).
-		 */
-		split++;
-	}
-
-	/*
-	 * Then, anything to the left of 'split' must be in a new pack. But,
-	 * creating that new pack may cause packs in the heavy half to no longer
-	 * form a geometric progression.
-	 *
-	 * Compute an expected size of the new pack, and then determine how many
-	 * packs in the heavy half need to be joined into it (if any) to restore
-	 * the geometric progression.
-	 */
-	for (i = 0; i < split; i++) {
-		struct packed_git *p = geometry->pack[i];
-
-		if (unsigned_add_overflows(total_size, pack_geometry_weight(p)))
-			die(_("pack %s too large to roll up"), p->pack_name);
-		total_size += pack_geometry_weight(p);
-	}
-	for (i = split; i < geometry->pack_nr; i++) {
-		struct packed_git *ours = geometry->pack[i];
-
-		if (unsigned_mult_overflows(geometry->split_factor,
-					    total_size))
-			die(_("pack %s too large to roll up"), ours->pack_name);
-
-		if (pack_geometry_weight(ours) <
-		    geometry->split_factor * total_size) {
-			if (unsigned_add_overflows(total_size,
-						   pack_geometry_weight(ours)))
-				die(_("pack %s too large to roll up"),
-				    ours->pack_name);
-
-			split++;
-			total_size += pack_geometry_weight(ours);
-		} else
-			break;
-	}
-
-	geometry->split = split;
-}
-
-static struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geometry)
-{
-	uint32_t i;
-
-	if (!geometry) {
-		/*
-		 * No geometry means either an all-into-one repack (in which
-		 * case there is only one pack left and it is the largest) or an
-		 * incremental one.
-		 *
-		 * If repacking incrementally, then we could check the size of
-		 * all packs to determine which should be preferred, but leave
-		 * this for later.
-		 */
-		return NULL;
-	}
-	if (geometry->split == geometry->pack_nr)
-		return NULL;
-
-	/*
-	 * The preferred pack is the largest pack above the split line. In
-	 * other words, it is the largest pack that does not get rolled up in
-	 * the geometric repack.
-	 */
-	for (i = geometry->pack_nr; i > geometry->split; i--)
-		/*
-		 * A pack that is not local would never be included in a
-		 * multi-pack index. We thus skip over any non-local packs.
-		 */
-		if (geometry->pack[i - 1]->pack_local)
-			return geometry->pack[i - 1];
-
-	return NULL;
-}
-
-static void pack_geometry_remove_redundant(struct pack_geometry *geometry,
-					   struct string_list *names,
-					   struct existing_packs *existing,
-					   const char *packdir)
-{
-	const struct git_hash_algo *algop = existing->repo->hash_algo;
-	struct strbuf buf = STRBUF_INIT;
-	uint32_t i;
-
-	for (i = 0; i < geometry->split; i++) {
-		struct packed_git *p = geometry->pack[i];
-		if (string_list_has_string(names, hash_to_hex_algop(p->hash,
-								    algop)))
-			continue;
-
-		strbuf_reset(&buf);
-		strbuf_addstr(&buf, pack_basename(p));
-		strbuf_strip_suffix(&buf, ".pack");
-
-		if ((p->pack_keep) ||
-		    (string_list_has_string(&existing->kept_packs, buf.buf)))
-			continue;
-
-		repack_remove_redundant_pack(existing->repo, packdir, buf.buf);
-	}
-
-	strbuf_release(&buf);
-}
-
-static void pack_geometry_release(struct pack_geometry *geometry)
-{
-	if (!geometry)
-		return;
-
-	free(geometry->pack);
-}
-
 static int midx_has_unknown_packs(char **midx_pack_names,
 				  size_t midx_pack_names_nr,
 				  struct string_list *include,
diff --git a/meson.build b/meson.build
index ca5603b456..c929ad6f7e 100644
--- a/meson.build
+++ b/meson.build
@@ -463,6 +463,7 @@ libgit_sources = [
   'reftable/writer.c',
   'remote.c',
   'repack.c',
+  'repack-geometry.c',
   'repack-promisor.c',
   'replace-object.c',
   'repo-settings.c',
diff --git a/repack-geometry.c b/repack-geometry.c
new file mode 100644
index 0000000000..a879f2fe49
--- /dev/null
+++ b/repack-geometry.c
@@ -0,0 +1,233 @@
+#define DISABLE_SIGN_COMPARE_WARNINGS
+
+#include "git-compat-util.h"
+#include "repack.h"
+#include "hex.h"
+#include "packfile.h"
+
+static uint32_t pack_geometry_weight(struct packed_git *p)
+{
+	if (open_pack_index(p))
+		die(_("cannot open index for %s"), p->pack_name);
+	return p->num_objects;
+}
+
+static int pack_geometry_cmp(const void *va, const void *vb)
+{
+	uint32_t aw = pack_geometry_weight(*(struct packed_git **)va),
+		 bw = pack_geometry_weight(*(struct packed_git **)vb);
+
+	if (aw < bw)
+		return -1;
+	if (aw > bw)
+		return 1;
+	return 0;
+}
+
+void pack_geometry_init(struct pack_geometry *geometry,
+			struct existing_packs *existing,
+			const struct pack_objects_args *args,
+			int pack_kept_objects)
+{
+	struct packfile_store *packs = existing->repo->objects->packfiles;
+	struct packed_git *p;
+	struct strbuf buf = STRBUF_INIT;
+
+	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
+		if (args->local && !p->pack_local)
+			/*
+			 * When asked to only repack local packfiles we skip
+			 * over any packfiles that are borrowed from alternate
+			 * object directories.
+			 */
+			continue;
+
+		if (!pack_kept_objects) {
+			/*
+			 * Any pack that has its pack_keep bit set will
+			 * appear in existing->kept_packs below, but
+			 * this saves us from doing a more expensive
+			 * check.
+			 */
+			if (p->pack_keep)
+				continue;
+
+			/*
+			 * The pack may be kept via the --keep-pack
+			 * option; check 'existing->kept_packs' to
+			 * determine whether to ignore it.
+			 */
+			strbuf_reset(&buf);
+			strbuf_addstr(&buf, pack_basename(p));
+			strbuf_strip_suffix(&buf, ".pack");
+
+			if (string_list_has_string(&existing->kept_packs, buf.buf))
+				continue;
+		}
+		if (p->is_cruft)
+			continue;
+
+		ALLOC_GROW(geometry->pack,
+			   geometry->pack_nr + 1,
+			   geometry->pack_alloc);
+
+		geometry->pack[geometry->pack_nr] = p;
+		geometry->pack_nr++;
+	}
+
+	QSORT(geometry->pack, geometry->pack_nr, pack_geometry_cmp);
+	strbuf_release(&buf);
+}
+
+void pack_geometry_split(struct pack_geometry *geometry)
+{
+	uint32_t i;
+	uint32_t split;
+	off_t total_size = 0;
+
+	if (!geometry->pack_nr) {
+		geometry->split = geometry->pack_nr;
+		return;
+	}
+
+	/*
+	 * First, count the number of packs (in descending order of size) which
+	 * already form a geometric progression.
+	 */
+	for (i = geometry->pack_nr - 1; i > 0; i--) {
+		struct packed_git *ours = geometry->pack[i];
+		struct packed_git *prev = geometry->pack[i - 1];
+
+		if (unsigned_mult_overflows(geometry->split_factor,
+					    pack_geometry_weight(prev)))
+			die(_("pack %s too large to consider in geometric "
+			      "progression"),
+			    prev->pack_name);
+
+		if (pack_geometry_weight(ours) <
+		    geometry->split_factor * pack_geometry_weight(prev))
+			break;
+	}
+
+	split = i;
+
+	if (split) {
+		/*
+		 * Move the split one to the right, since the top element in the
+		 * last-compared pair can't be in the progression. Only do this
+		 * when we split in the middle of the array (otherwise if we got
+		 * to the end, then the split is in the right place).
+		 */
+		split++;
+	}
+
+	/*
+	 * Then, anything to the left of 'split' must be in a new pack. But,
+	 * creating that new pack may cause packs in the heavy half to no longer
+	 * form a geometric progression.
+	 *
+	 * Compute an expected size of the new pack, and then determine how many
+	 * packs in the heavy half need to be joined into it (if any) to restore
+	 * the geometric progression.
+	 */
+	for (i = 0; i < split; i++) {
+		struct packed_git *p = geometry->pack[i];
+
+		if (unsigned_add_overflows(total_size, pack_geometry_weight(p)))
+			die(_("pack %s too large to roll up"), p->pack_name);
+		total_size += pack_geometry_weight(p);
+	}
+	for (i = split; i < geometry->pack_nr; i++) {
+		struct packed_git *ours = geometry->pack[i];
+
+		if (unsigned_mult_overflows(geometry->split_factor,
+					    total_size))
+			die(_("pack %s too large to roll up"), ours->pack_name);
+
+		if (pack_geometry_weight(ours) <
+		    geometry->split_factor * total_size) {
+			if (unsigned_add_overflows(total_size,
+						   pack_geometry_weight(ours)))
+				die(_("pack %s too large to roll up"),
+				    ours->pack_name);
+
+			split++;
+			total_size += pack_geometry_weight(ours);
+		} else
+			break;
+	}
+
+	geometry->split = split;
+}
+
+struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geometry)
+{
+	uint32_t i;
+
+	if (!geometry) {
+		/*
+		 * No geometry means either an all-into-one repack (in which
+		 * case there is only one pack left and it is the largest) or an
+		 * incremental one.
+		 *
+		 * If repacking incrementally, then we could check the size of
+		 * all packs to determine which should be preferred, but leave
+		 * this for later.
+		 */
+		return NULL;
+	}
+	if (geometry->split == geometry->pack_nr)
+		return NULL;
+
+	/*
+	 * The preferred pack is the largest pack above the split line. In
+	 * other words, it is the largest pack that does not get rolled up in
+	 * the geometric repack.
+	 */
+	for (i = geometry->pack_nr; i > geometry->split; i--)
+		/*
+		 * A pack that is not local would never be included in a
+		 * multi-pack index. We thus skip over any non-local packs.
+		 */
+		if (geometry->pack[i - 1]->pack_local)
+			return geometry->pack[i - 1];
+
+	return NULL;
+}
+
+void pack_geometry_remove_redundant(struct pack_geometry *geometry,
+				    struct string_list *names,
+				    struct existing_packs *existing,
+				    const char *packdir)
+{
+	const struct git_hash_algo *algop = existing->repo->hash_algo;
+	struct strbuf buf = STRBUF_INIT;
+	uint32_t i;
+
+	for (i = 0; i < geometry->split; i++) {
+		struct packed_git *p = geometry->pack[i];
+		if (string_list_has_string(names, hash_to_hex_algop(p->hash,
+								    algop)))
+			continue;
+
+		strbuf_reset(&buf);
+		strbuf_addstr(&buf, pack_basename(p));
+		strbuf_strip_suffix(&buf, ".pack");
+
+		if ((p->pack_keep) ||
+		    (string_list_has_string(&existing->kept_packs, buf.buf)))
+			continue;
+
+		repack_remove_redundant_pack(existing->repo, packdir, buf.buf);
+	}
+
+	strbuf_release(&buf);
+}
+
+void pack_geometry_release(struct pack_geometry *geometry)
+{
+	if (!geometry)
+		return;
+
+	free(geometry->pack);
+}
diff --git a/repack.h b/repack.h
index 19dc4fd738..cea7969ae4 100644
--- a/repack.h
+++ b/repack.h
@@ -78,4 +78,24 @@ void repack_promisor_objects(struct repository *repo,
 			     const struct pack_objects_args *args,
 			     struct string_list *names, const char *packtmp);
 
+struct pack_geometry {
+	struct packed_git **pack;
+	uint32_t pack_nr, pack_alloc;
+	uint32_t split;
+
+	int split_factor;
+};
+
+void pack_geometry_init(struct pack_geometry *geometry,
+			struct existing_packs *existing,
+			const struct pack_objects_args *args,
+			int pack_kept_objects);
+void pack_geometry_split(struct pack_geometry *geometry);
+struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geometry);
+void pack_geometry_remove_redundant(struct pack_geometry *geometry,
+				    struct string_list *names,
+				    struct existing_packs *existing,
+				    const char *packdir);
+void pack_geometry_release(struct pack_geometry *geometry);
+
 #endif /* REPACK_H */

Makefile, builtin/repack.c, meson.build, repack-midx.c, repack.h

diff --git a/Makefile b/Makefile
index a6da12a326..3360743afb 100644
--- a/Makefile
+++ b/Makefile
@@ -1138,6 +1138,7 @@ LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
 LIB_OBJS += repack-geometry.o
+LIB_OBJS += repack-midx.o
 LIB_OBJS += repack-promisor.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o
diff --git a/builtin/repack.c b/builtin/repack.c
index b49e2dab9a..5a1f1cb562 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -178,74 +178,6 @@ static int midx_has_unknown_packs(char **midx_pack_names,
 	return 0;
 }
 
-struct midx_snapshot_ref_data {
-	struct repository *repo;
-	struct tempfile *f;
-	struct oidset seen;
-	int preferred;
-};
-
-static int midx_snapshot_ref_one(const char *refname UNUSED,
-				 const char *referent UNUSED,
-				 const struct object_id *oid,
-				 int flag UNUSED, void *_data)
-{
-	struct midx_snapshot_ref_data *data = _data;
-	struct object_id peeled;
-
-	if (!peel_iterated_oid(data->repo, oid, &peeled))
-		oid = &peeled;
-
-	if (oidset_insert(&data->seen, oid))
-		return 0; /* already seen */
-
-	if (odb_read_object_info(data->repo->objects, oid, NULL) != OBJ_COMMIT)
-		return 0;
-
-	fprintf(data->f->fp, "%s%s\n", data->preferred ? "+" : "",
-		oid_to_hex(oid));
-
-	return 0;
-}
-
-static void midx_snapshot_refs(struct repository *repo, struct tempfile *f)
-{
-	struct midx_snapshot_ref_data data;
-	const struct string_list *preferred = bitmap_preferred_tips(repo);
-
-	data.repo = repo;
-	data.f = f;
-	data.preferred = 0;
-	oidset_init(&data.seen, 0);
-
-	if (!fdopen_tempfile(f, "w"))
-		 die(_("could not open tempfile %s for writing"),
-		     get_tempfile_path(f));
-
-	if (preferred) {
-		struct string_list_item *item;
-
-		data.preferred = 1;
-		for_each_string_list_item(item, preferred)
-			refs_for_each_ref_in(get_main_ref_store(repo),
-					     item->string,
-					     midx_snapshot_ref_one, &data);
-		data.preferred = 0;
-	}
-
-	refs_for_each_ref(get_main_ref_store(repo),
-			  midx_snapshot_ref_one, &data);
-
-	if (close_tempfile_gently(f)) {
-		int save_errno = errno;
-		delete_tempfile(&f);
-		errno = save_errno;
-		die_errno(_("could not close refs snapshot tempfile"));
-	}
-
-	oidset_clear(&data.seen);
-}
-
 static void midx_included_packs(struct string_list *include,
 				struct existing_packs *existing,
 				char **midx_pack_names,
diff --git a/meson.build b/meson.build
index c929ad6f7e..42171d1851 100644
--- a/meson.build
+++ b/meson.build
@@ -464,6 +464,7 @@ libgit_sources = [
   'remote.c',
   'repack.c',
   'repack-geometry.c',
+  'repack-midx.c',
   'repack-promisor.c',
   'replace-object.c',
   'repo-settings.c',
diff --git a/repack-midx.c b/repack-midx.c
new file mode 100644
index 0000000000..354df729a5
--- /dev/null
+++ b/repack-midx.c
@@ -0,0 +1,77 @@
+#include "git-compat-util.h"
+#include "repack.h"
+#include "hash.h"
+#include "hex.h"
+#include "odb.h"
+#include "oidset.h"
+#include "pack-bitmap.h"
+#include "refs.h"
+#include "tempfile.h"
+
+struct midx_snapshot_ref_data {
+	struct repository *repo;
+	struct tempfile *f;
+	struct oidset seen;
+	int preferred;
+};
+
+static int midx_snapshot_ref_one(const char *refname UNUSED,
+				 const char *referent UNUSED,
+				 const struct object_id *oid,
+				 int flag UNUSED, void *_data)
+{
+	struct midx_snapshot_ref_data *data = _data;
+	struct object_id peeled;
+
+	if (!peel_iterated_oid(data->repo, oid, &peeled))
+		oid = &peeled;
+
+	if (oidset_insert(&data->seen, oid))
+		return 0; /* already seen */
+
+	if (odb_read_object_info(data->repo->objects, oid, NULL) != OBJ_COMMIT)
+		return 0;
+
+	fprintf(data->f->fp, "%s%s\n", data->preferred ? "+" : "",
+		oid_to_hex(oid));
+
+	return 0;
+}
+
+void midx_snapshot_refs(struct repository *repo, struct tempfile *f)
+{
+	struct midx_snapshot_ref_data data;
+	const struct string_list *preferred = bitmap_preferred_tips(repo);
+
+	data.repo = repo;
+	data.f = f;
+	data.preferred = 0;
+	oidset_init(&data.seen, 0);
+
+	if (!fdopen_tempfile(f, "w"))
+		 die(_("could not open tempfile %s for writing"),
+		     get_tempfile_path(f));
+
+	if (preferred) {
+		struct string_list_item *item;
+
+		data.preferred = 1;
+		for_each_string_list_item(item, preferred)
+			refs_for_each_ref_in(get_main_ref_store(repo),
+					     item->string,
+					     midx_snapshot_ref_one, &data);
+		data.preferred = 0;
+	}
+
+	refs_for_each_ref(get_main_ref_store(repo),
+			  midx_snapshot_ref_one, &data);
+
+	if (close_tempfile_gently(f)) {
+		int save_errno = errno;
+		delete_tempfile(&f);
+		errno = save_errno;
+		die_errno(_("could not close refs snapshot tempfile"));
+	}
+
+	oidset_clear(&data.seen);
+}
diff --git a/repack.h b/repack.h
index cea7969ae4..803e129224 100644
--- a/repack.h
+++ b/repack.h
@@ -98,4 +98,8 @@ void pack_geometry_remove_redundant(struct pack_geometry *geometry,
 				    const char *packdir);
 void pack_geometry_release(struct pack_geometry *geometry);
 
+struct tempfile;
+
+void midx_snapshot_refs(struct repository *repo, struct tempfile *f);
+
 #endif /* REPACK_H */

diff --git a/builtin/repack.c b/builtin/repack.c
index 5a1f1cb562..e4b8aa2c6f 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -107,6 +107,17 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
+struct repack_write_midx_opts {
+	struct string_list *include;
+	struct pack_geometry *geometry;
+	struct string_list *names;
+	const char *refs_snapshot;
+	const char *packdir;
+	int show_progress;
+	int write_bitmaps;
+	int midx_must_contain_cruft;
+};
+
 static int midx_has_unknown_packs(char **midx_pack_names,
 				  size_t midx_pack_names_nr,
 				  struct string_list *include,
@@ -290,19 +301,15 @@ static void midx_included_packs(struct string_list *include,
 	strbuf_release(&buf);
 }
 
-static int write_midx_included_packs(struct string_list *include,
-				     struct pack_geometry *geometry,
-				     struct string_list *names,
-				     const char *refs_snapshot,
-				     int show_progress, int write_bitmaps)
+static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
-	struct packed_git *preferred = pack_geometry_preferred_pack(geometry);
+	struct packed_git *preferred = pack_geometry_preferred_pack(opts->geometry);
 	FILE *in;
 	int ret;
 
-	if (!include->nr)
+	if (!opts->include->nr)
 		return 0;
 
 	cmd.in = -1;
@@ -311,18 +318,18 @@ static int write_midx_included_packs(struct string_list *include,
 	strvec_push(&cmd.args, "multi-pack-index");
 	strvec_pushl(&cmd.args, "write", "--stdin-packs", NULL);
 
-	if (show_progress)
+	if (opts->show_progress)
 		strvec_push(&cmd.args, "--progress");
 	else
 		strvec_push(&cmd.args, "--no-progress");
 
-	if (write_bitmaps)
+	if (opts->write_bitmaps)
 		strvec_push(&cmd.args, "--bitmap");
 
 	if (preferred)
 		strvec_pushf(&cmd.args, "--preferred-pack=%s",
 			     pack_basename(preferred));
-	else if (names->nr) {
+	else if (opts->names->nr) {
 		/* The largest pack was repacked, meaning that either
 		 * one or two packs exist depending on whether the
 		 * repository has a cruft pack or not.
@@ -335,7 +342,7 @@ static int write_midx_included_packs(struct string_list *include,
 		 * `--max-pack-size` was given, but any one of them
 		 * will suffice, so pick the first one.)
 		 */
-		for_each_string_list_item(item, names) {
+		for_each_string_list_item(item, opts->names) {
 			struct generated_pack *pack = item->util;
 			if (generated_pack_has_ext(pack, ".mtimes"))
 				continue;
@@ -355,15 +362,16 @@ static int write_midx_included_packs(struct string_list *include,
 		;
 	}
 
-	if (refs_snapshot)
-		strvec_pushf(&cmd.args, "--refs-snapshot=%s", refs_snapshot);
+	if (opts->refs_snapshot)
+		strvec_pushf(&cmd.args, "--refs-snapshot=%s",
+			     opts->refs_snapshot);
 
 	ret = start_command(&cmd);
 	if (ret)
 		return ret;
 
 	in = xfdopen(cmd.in, "w");
-	for_each_string_list_item(item, include)
+	for_each_string_list_item(item, opts->include)
 		fprintf(in, "%s\n", item->string);
 	fclose(in);
 
@@ -1001,15 +1009,23 @@ int cmd_repack(int argc,
 
 	if (write_midx) {
 		struct string_list include = STRING_LIST_INIT_DUP;
+		struct repack_write_midx_opts opts = {
+			.include = &include,
+			.geometry = &geometry,
+			.names = &names,
+			.refs_snapshot = refs_snapshot ? get_tempfile_path(refs_snapshot) : NULL,
+			.packdir = packdir,
+			.show_progress = show_progress,
+			.write_bitmaps = write_bitmaps > 0,
+			.midx_must_contain_cruft = midx_must_contain_cruft
+		};
 		midx_included_packs(&include, &existing, midx_pack_names,
 				    midx_pack_names_nr, &names, &geometry);
 
-		ret = write_midx_included_packs(&include, &geometry, &names,
-						refs_snapshot ? get_tempfile_path(refs_snapshot) : NULL,
-						show_progress, write_bitmaps > 0);
+		ret = write_midx_included_packs(&opts);
 
 		if (!ret && write_bitmaps)
-			remove_redundant_bitmaps(&include, packdir);
+			remove_redundant_bitmaps(&include, opts.packdir);
 
 		string_list_clear(&include, 0);
 

diff --git a/builtin/repack.c b/builtin/repack.c
index e4b8aa2c6f..8ae56b05e9 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -118,18 +118,17 @@ struct repack_write_midx_opts {
 	int midx_must_contain_cruft;
 };
 
-static int midx_has_unknown_packs(char **midx_pack_names,
-				  size_t midx_pack_names_nr,
+static int midx_has_unknown_packs(struct string_list *midx_pack_names,
 				  struct string_list *include,
 				  struct pack_geometry *geometry,
 				  struct existing_packs *existing)
 {
-	size_t i;
+	struct string_list_item *item;
 
 	string_list_sort(include);
 
-	for (i = 0; i < midx_pack_names_nr; i++) {
-		const char *pack_name = midx_pack_names[i];
+	for_each_string_list_item(item, midx_pack_names) {
+		const char *pack_name = item->string;
 
 		/*
 		 * Determine whether or not each MIDX'd pack from the existing
@@ -191,8 +190,7 @@ static int midx_has_unknown_packs(char **midx_pack_names,
 
 static void midx_included_packs(struct string_list *include,
 				struct existing_packs *existing,
-				char **midx_pack_names,
-				size_t midx_pack_names_nr,
+				struct string_list *midx_pack_names,
 				struct string_list *names,
 				struct pack_geometry *geometry)
 {
@@ -247,8 +245,8 @@ static void midx_included_packs(struct string_list *include,
 	}
 
 	if (midx_must_contain_cruft ||
-	    midx_has_unknown_packs(midx_pack_names, midx_pack_names_nr,
-				   include, geometry, existing)) {
+	    midx_has_unknown_packs(midx_pack_names, include, geometry,
+				   existing)) {
 		/*
 		 * If there are one or more unknown pack(s) present (see
 		 * midx_has_unknown_packs() for what makes a pack
@@ -606,13 +604,12 @@ int cmd_repack(int argc,
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
 	struct string_list names = STRING_LIST_INIT_DUP;
+	struct string_list midx_pack_names = STRING_LIST_INIT_DUP;
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
 	struct tempfile *refs_snapshot = NULL;
 	int i, ret;
 	int show_progress;
-	char **midx_pack_names = NULL;
-	size_t midx_pack_names_nr = 0;
 
 	/* variables to be filled by option parsing */
 	struct repack_config_ctx config_ctx;
@@ -985,13 +982,12 @@ int cmd_repack(int argc,
 		struct multi_pack_index *m =
 			get_multi_pack_index(repo->objects->sources);
 
-		ALLOC_ARRAY(midx_pack_names,
-			    m->num_packs + m->num_packs_in_base);
-
-		for (; m; m = m->base_midx)
-			for (uint32_t i = 0; i < m->num_packs; i++)
-				midx_pack_names[midx_pack_names_nr++] =
-					xstrdup(m->pack_names[i]);
+		for (; m; m = m->base_midx) {
+			for (uint32_t i = 0; i < m->num_packs; i++) {
+				string_list_append(&midx_pack_names,
+						   m->pack_names[i]);
+			}
+		}
 	}
 
 	close_object_store(repo->objects);
@@ -1019,8 +1015,8 @@ int cmd_repack(int argc,
 			.write_bitmaps = write_bitmaps > 0,
 			.midx_must_contain_cruft = midx_must_contain_cruft
 		};
-		midx_included_packs(&include, &existing, midx_pack_names,
-				    midx_pack_names_nr, &names, &geometry);
+		midx_included_packs(&include, &existing, &midx_pack_names,
+				    &names, &geometry);
 
 		ret = write_midx_included_packs(&opts);
 
@@ -1067,11 +1063,9 @@ int cmd_repack(int argc,
 cleanup:
 	string_list_clear(&keep_pack_list, 0);
 	string_list_clear(&names, 1);
+	string_list_clear(&midx_pack_names, 0);
 	existing_packs_release(&existing);
 	pack_geometry_release(&geometry);
-	for (size_t i = 0; i < midx_pack_names_nr; i++)
-		free(midx_pack_names[i]);
-	free(midx_pack_names);
 	pack_objects_args_release(&po_args);
 	pack_objects_args_release(&cruft_po_args);
 

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index 8ae56b05e9..251dd08b0a 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -118,8 +118,7 @@ struct repack_write_midx_opts {
 	int midx_must_contain_cruft;
 };
 
-static int midx_has_unknown_packs(struct string_list *midx_pack_names,
-				  struct string_list *include,
+static int midx_has_unknown_packs(struct string_list *include,
 				  struct pack_geometry *geometry,
 				  struct existing_packs *existing)
 {
@@ -127,7 +126,7 @@ static int midx_has_unknown_packs(struct string_list *midx_pack_names,
 
 	string_list_sort(include);
 
-	for_each_string_list_item(item, midx_pack_names) {
+	for_each_string_list_item(item, &existing->midx_packs) {
 		const char *pack_name = item->string;
 
 		/*
@@ -190,7 +189,6 @@ static int midx_has_unknown_packs(struct string_list *midx_pack_names,
 
 static void midx_included_packs(struct string_list *include,
 				struct existing_packs *existing,
-				struct string_list *midx_pack_names,
 				struct string_list *names,
 				struct pack_geometry *geometry)
 {
@@ -245,8 +243,7 @@ static void midx_included_packs(struct string_list *include,
 	}
 
 	if (midx_must_contain_cruft ||
-	    midx_has_unknown_packs(midx_pack_names, include, geometry,
-				   existing)) {
+	    midx_has_unknown_packs(include, geometry, existing)) {
 		/*
 		 * If there are one or more unknown pack(s) present (see
 		 * midx_has_unknown_packs() for what makes a pack
@@ -604,7 +601,6 @@ int cmd_repack(int argc,
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	struct string_list_item *item;
 	struct string_list names = STRING_LIST_INIT_DUP;
-	struct string_list midx_pack_names = STRING_LIST_INIT_DUP;
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
 	struct tempfile *refs_snapshot = NULL;
@@ -978,18 +974,6 @@ int cmd_repack(int argc,
 
 	string_list_sort(&names);
 
-	if (get_multi_pack_index(repo->objects->sources)) {
-		struct multi_pack_index *m =
-			get_multi_pack_index(repo->objects->sources);
-
-		for (; m; m = m->base_midx) {
-			for (uint32_t i = 0; i < m->num_packs; i++) {
-				string_list_append(&midx_pack_names,
-						   m->pack_names[i]);
-			}
-		}
-	}
-
 	close_object_store(repo->objects);
 
 	/*
@@ -1015,8 +999,7 @@ int cmd_repack(int argc,
 			.write_bitmaps = write_bitmaps > 0,
 			.midx_must_contain_cruft = midx_must_contain_cruft
 		};
-		midx_included_packs(&include, &existing, &midx_pack_names,
-				    &names, &geometry);
+		midx_included_packs(&include, &existing, &names, &geometry);
 
 		ret = write_midx_included_packs(&opts);
 
@@ -1063,7 +1046,6 @@ int cmd_repack(int argc,
 cleanup:
 	string_list_clear(&keep_pack_list, 0);
 	string_list_clear(&names, 1);
-	string_list_clear(&midx_pack_names, 0);
 	existing_packs_release(&existing);
 	pack_geometry_release(&geometry);
 	pack_objects_args_release(&po_args);
diff --git a/repack.c b/repack.c
index d8afdd352d..1d485e0112 100644
--- a/repack.c
+++ b/repack.c
@@ -80,6 +80,9 @@ void existing_packs_collect(struct existing_packs *existing,
 		size_t i;
 		const char *base;
 
+		if (p->multi_pack_index)
+			string_list_append(&existing->midx_packs,
+					    pack_basename(p));
 		if (!p->pack_local)
 			continue;
 
@@ -104,6 +107,7 @@ void existing_packs_collect(struct existing_packs *existing,
 	string_list_sort(&existing->kept_packs);
 	string_list_sort(&existing->non_kept_packs);
 	string_list_sort(&existing->cruft_packs);
+	string_list_sort(&existing->midx_packs);
 	strbuf_release(&buf);
 }
 
@@ -220,6 +224,7 @@ void existing_packs_release(struct existing_packs *existing)
 	string_list_clear(&existing->kept_packs, 0);
 	string_list_clear(&existing->non_kept_packs, 0);
 	string_list_clear(&existing->cruft_packs, 0);
+	string_list_clear(&existing->midx_packs, 0);
 }
 
 static struct {
diff --git a/repack.h b/repack.h
index 803e129224..6aa5b4e0f0 100644
--- a/repack.h
+++ b/repack.h
@@ -40,6 +40,7 @@ struct existing_packs {
 	struct string_list kept_packs;
 	struct string_list non_kept_packs;
 	struct string_list cruft_packs;
+	struct string_list midx_packs;
 };
 
 #define EXISTING_PACKS_INIT { \

diff --git a/builtin/repack.c b/builtin/repack.c
index 251dd08b0a..957a9b5f9e 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -296,6 +296,35 @@ static void midx_included_packs(struct string_list *include,
 	strbuf_release(&buf);
 }
 
+static void remove_redundant_bitmaps(struct string_list *include,
+				     const char *packdir)
+{
+	struct strbuf path = STRBUF_INIT;
+	struct string_list_item *item;
+	size_t packdir_len;
+
+	strbuf_addstr(&path, packdir);
+	strbuf_addch(&path, '/');
+	packdir_len = path.len;
+
+	/*
+	 * Remove any pack bitmaps corresponding to packs which are now
+	 * included in the MIDX.
+	 */
+	for_each_string_list_item(item, include) {
+		strbuf_addstr(&path, item->string);
+		strbuf_strip_suffix(&path, ".idx");
+		strbuf_addstr(&path, ".bitmap");
+
+		if (unlink(path.buf) && errno != ENOENT)
+			warning_errno(_("could not remove stale bitmap: %s"),
+				      path.buf);
+
+		strbuf_setlen(&path, packdir_len);
+	}
+	strbuf_release(&path);
+}
+
 static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
@@ -373,35 +402,6 @@ static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 	return finish_command(&cmd);
 }
 
-static void remove_redundant_bitmaps(struct string_list *include,
-				     const char *packdir)
-{
-	struct strbuf path = STRBUF_INIT;
-	struct string_list_item *item;
-	size_t packdir_len;
-
-	strbuf_addstr(&path, packdir);
-	strbuf_addch(&path, '/');
-	packdir_len = path.len;
-
-	/*
-	 * Remove any pack bitmaps corresponding to packs which are now
-	 * included in the MIDX.
-	 */
-	for_each_string_list_item(item, include) {
-		strbuf_addstr(&path, item->string);
-		strbuf_strip_suffix(&path, ".idx");
-		strbuf_addstr(&path, ".bitmap");
-
-		if (unlink(path.buf) && errno != ENOENT)
-			warning_errno(_("could not remove stale bitmap: %s"),
-				      path.buf);
-
-		strbuf_setlen(&path, packdir_len);
-	}
-	strbuf_release(&path);
-}
-
 static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
 				   struct child_process *cmd,
 				   struct string_list *names,

diff --git a/builtin/repack.c b/builtin/repack.c
index 957a9b5f9e..b55c8934e8 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -331,10 +331,10 @@ static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 	struct string_list_item *item;
 	struct packed_git *preferred = pack_geometry_preferred_pack(opts->geometry);
 	FILE *in;
-	int ret;
+	int ret = 0;
 
 	if (!opts->include->nr)
-		return 0;
+		goto done;
 
 	cmd.in = -1;
 	cmd.git_cmd = 1;
@@ -392,14 +392,18 @@ static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 
 	ret = start_command(&cmd);
 	if (ret)
-		return ret;
+		goto done;
 
 	in = xfdopen(cmd.in, "w");
 	for_each_string_list_item(item, opts->include)
 		fprintf(in, "%s\n", item->string);
 	fclose(in);
 
-	return finish_command(&cmd);
+	ret = finish_command(&cmd);
+done:
+	if (!ret && opts->write_bitmaps)
+		remove_redundant_bitmaps(opts->include, opts->packdir);
+	return ret;
 }
 
 static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
@@ -1003,9 +1007,6 @@ int cmd_repack(int argc,
 
 		ret = write_midx_included_packs(&opts);
 
-		if (!ret && write_bitmaps)
-			remove_redundant_bitmaps(&include, opts.packdir);
-
 		string_list_clear(&include, 0);
 
 		if (ret)

diff --git a/builtin/repack.c b/builtin/repack.c
index b55c8934e8..bd3034a4f0 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -108,6 +108,7 @@ static int repack_config(const char *var, const char *value,
 }
 
 struct repack_write_midx_opts {
+	struct existing_packs *existing;
 	struct string_list *include;
 	struct pack_geometry *geometry;
 	struct string_list *names;
@@ -188,10 +189,11 @@ static int midx_has_unknown_packs(struct string_list *include,
 }
 
 static void midx_included_packs(struct string_list *include,
-				struct existing_packs *existing,
-				struct string_list *names,
-				struct pack_geometry *geometry)
+				struct repack_write_midx_opts *opts)
 {
+	struct existing_packs *existing = opts->existing;
+	struct pack_geometry *geometry = opts->geometry;
+	struct string_list *names = opts->names;
 	struct string_list_item *item;
 	struct strbuf buf = STRBUF_INIT;
 
@@ -242,7 +244,7 @@ static void midx_included_packs(struct string_list *include,
 		}
 	}
 
-	if (midx_must_contain_cruft ||
+	if (opts->midx_must_contain_cruft ||
 	    midx_has_unknown_packs(include, geometry, existing)) {
 		/*
 		 * If there are one or more unknown pack(s) present (see
@@ -994,6 +996,7 @@ int cmd_repack(int argc,
 	if (write_midx) {
 		struct string_list include = STRING_LIST_INIT_DUP;
 		struct repack_write_midx_opts opts = {
+			.existing = &existing,
 			.include = &include,
 			.geometry = &geometry,
 			.names = &names,
@@ -1003,7 +1006,7 @@ int cmd_repack(int argc,
 			.write_bitmaps = write_bitmaps > 0,
 			.midx_must_contain_cruft = midx_must_contain_cruft
 		};
-		midx_included_packs(&include, &existing, &names, &geometry);
+		midx_included_packs(&include, &opts);
 
 		ret = write_midx_included_packs(&opts);
 

diff --git a/builtin/repack.c b/builtin/repack.c
index bd3034a4f0..e2acba6312 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -109,7 +109,6 @@ static int repack_config(const char *var, const char *value,
 
 struct repack_write_midx_opts {
 	struct existing_packs *existing;
-	struct string_list *include;
 	struct pack_geometry *geometry;
 	struct string_list *names;
 	const char *refs_snapshot;
@@ -330,12 +329,14 @@ static void remove_redundant_bitmaps(struct string_list *include,
 static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct string_list include = STRING_LIST_INIT_DUP;
 	struct string_list_item *item;
 	struct packed_git *preferred = pack_geometry_preferred_pack(opts->geometry);
 	FILE *in;
 	int ret = 0;
 
-	if (!opts->include->nr)
+	midx_included_packs(&include, opts);
+	if (!include.nr)
 		goto done;
 
 	cmd.in = -1;
@@ -397,14 +398,17 @@ static int write_midx_included_packs(struct repack_write_midx_opts *opts)
 		goto done;
 
 	in = xfdopen(cmd.in, "w");
-	for_each_string_list_item(item, opts->include)
+	for_each_string_list_item(item, &include)
 		fprintf(in, "%s\n", item->string);
 	fclose(in);
 
 	ret = finish_command(&cmd);
 done:
 	if (!ret && opts->write_bitmaps)
-		remove_redundant_bitmaps(opts->include, opts->packdir);
+		remove_redundant_bitmaps(&include, opts->packdir);
+
+	string_list_clear(&include, 0);
+
 	return ret;
 }
 
@@ -994,10 +998,8 @@ int cmd_repack(int argc,
 		existing_packs_mark_for_deletion(&existing, &names);
 
 	if (write_midx) {
-		struct string_list include = STRING_LIST_INIT_DUP;
 		struct repack_write_midx_opts opts = {
 			.existing = &existing,
-			.include = &include,
 			.geometry = &geometry,
 			.names = &names,
 			.refs_snapshot = refs_snapshot ? get_tempfile_path(refs_snapshot) : NULL,
@@ -1006,12 +1008,9 @@ int cmd_repack(int argc,
 			.write_bitmaps = write_bitmaps > 0,
 			.midx_must_contain_cruft = midx_must_contain_cruft
 		};
-		midx_included_packs(&include, &opts);
 
 		ret = write_midx_included_packs(&opts);
 
-		string_list_clear(&include, 0);
-
 		if (ret)
 			goto cleanup;
 	}

builtin/repack.c, repack-midx.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index e2acba6312..5fed79e826 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -107,311 +107,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-struct repack_write_midx_opts {
-	struct existing_packs *existing;
-	struct pack_geometry *geometry;
-	struct string_list *names;
-	const char *refs_snapshot;
-	const char *packdir;
-	int show_progress;
-	int write_bitmaps;
-	int midx_must_contain_cruft;
-};
-
-static int midx_has_unknown_packs(struct string_list *include,
-				  struct pack_geometry *geometry,
-				  struct existing_packs *existing)
-{
-	struct string_list_item *item;
-
-	string_list_sort(include);
-
-	for_each_string_list_item(item, &existing->midx_packs) {
-		const char *pack_name = item->string;
-
-		/*
-		 * Determine whether or not each MIDX'd pack from the existing
-		 * MIDX (if any) is represented in the new MIDX. For each pack
-		 * in the MIDX, it must either be:
-		 *
-		 *  - In the "include" list of packs to be included in the new
-		 *    MIDX. Note this function is called before the include
-		 *    list is populated with any cruft pack(s).
-		 *
-		 *  - Below the geometric split line (if using pack geometry),
-		 *    indicating that the pack won't be included in the new
-		 *    MIDX, but its contents were rolled up as part of the
-		 *    geometric repack.
-		 *
-		 *  - In the existing non-kept packs list (if not using pack
-		 *    geometry), and marked as non-deleted.
-		 */
-		if (string_list_has_string(include, pack_name)) {
-			continue;
-		} else if (geometry) {
-			struct strbuf buf = STRBUF_INIT;
-			uint32_t j;
-
-			for (j = 0; j < geometry->split; j++) {
-				strbuf_reset(&buf);
-				strbuf_addstr(&buf, pack_basename(geometry->pack[j]));
-				strbuf_strip_suffix(&buf, ".pack");
-				strbuf_addstr(&buf, ".idx");
-
-				if (!strcmp(pack_name, buf.buf)) {
-					strbuf_release(&buf);
-					break;
-				}
-			}
-
-			strbuf_release(&buf);
-
-			if (j < geometry->split)
-				continue;
-		} else {
-			struct string_list_item *item;
-
-			item = string_list_lookup(&existing->non_kept_packs,
-						  pack_name);
-			if (item && !existing_pack_is_marked_for_deletion(item))
-				continue;
-		}
-
-		/*
-		 * If we got to this point, the MIDX includes some pack that we
-		 * don't know about.
-		 */
-		return 1;
-	}
-
-	return 0;
-}
-
-static void midx_included_packs(struct string_list *include,
-				struct repack_write_midx_opts *opts)
-{
-	struct existing_packs *existing = opts->existing;
-	struct pack_geometry *geometry = opts->geometry;
-	struct string_list *names = opts->names;
-	struct string_list_item *item;
-	struct strbuf buf = STRBUF_INIT;
-
-	for_each_string_list_item(item, &existing->kept_packs) {
-		strbuf_reset(&buf);
-		strbuf_addf(&buf, "%s.idx", item->string);
-		string_list_insert(include, buf.buf);
-	}
-
-	for_each_string_list_item(item, names) {
-		strbuf_reset(&buf);
-		strbuf_addf(&buf, "pack-%s.idx", item->string);
-		string_list_insert(include, buf.buf);
-	}
-
-	if (geometry->split_factor) {
-		uint32_t i;
-
-		for (i = geometry->split; i < geometry->pack_nr; i++) {
-			struct packed_git *p = geometry->pack[i];
-
-			/*
-			 * The multi-pack index never refers to packfiles part
-			 * of an alternate object database, so we skip these.
-			 * While git-multi-pack-index(1) would silently ignore
-			 * them anyway, this allows us to skip executing the
-			 * command completely when we have only non-local
-			 * packfiles.
-			 */
-			if (!p->pack_local)
-				continue;
-
-			strbuf_reset(&buf);
-			strbuf_addstr(&buf, pack_basename(p));
-			strbuf_strip_suffix(&buf, ".pack");
-			strbuf_addstr(&buf, ".idx");
-
-			string_list_insert(include, buf.buf);
-		}
-	} else {
-		for_each_string_list_item(item, &existing->non_kept_packs) {
-			if (existing_pack_is_marked_for_deletion(item))
-				continue;
-
-			strbuf_reset(&buf);
-			strbuf_addf(&buf, "%s.idx", item->string);
-			string_list_insert(include, buf.buf);
-		}
-	}
-
-	if (opts->midx_must_contain_cruft ||
-	    midx_has_unknown_packs(include, geometry, existing)) {
-		/*
-		 * If there are one or more unknown pack(s) present (see
-		 * midx_has_unknown_packs() for what makes a pack
-		 * "unknown") in the MIDX before the repack, keep them
-		 * as they may be required to form a reachability
-		 * closure if the MIDX is bitmapped.
-		 *
-		 * For example, a cruft pack can be required to form a
-		 * reachability closure if the MIDX is bitmapped and one
-		 * or more of the bitmap's selected commits reaches a
-		 * once-cruft object that was later made reachable.
-		 */
-		for_each_string_list_item(item, &existing->cruft_packs) {
-			/*
-			 * When doing a --geometric repack, there is no
-			 * need to check for deleted packs, since we're
-			 * by definition not doing an ALL_INTO_ONE
-			 * repack (hence no packs will be deleted).
-			 * Otherwise we must check for and exclude any
-			 * packs which are enqueued for deletion.
-			 *
-			 * So we could omit the conditional below in the
-			 * --geometric case, but doing so is unnecessary
-			 *  since no packs are marked as pending
-			 *  deletion (since we only call
-			 *  `existing_packs_mark_for_deletion()` when
-			 *  doing an all-into-one repack).
-			 */
-			if (existing_pack_is_marked_for_deletion(item))
-				continue;
-
-			strbuf_reset(&buf);
-			strbuf_addf(&buf, "%s.idx", item->string);
-			string_list_insert(include, buf.buf);
-		}
-	} else {
-		/*
-		 * Modern versions of Git (with the appropriate
-		 * configuration setting) will write new copies of
-		 * once-cruft objects when doing a --geometric repack.
-		 *
-		 * If the MIDX has no cruft pack, new packs written
-		 * during a --geometric repack will not rely on the
-		 * cruft pack to form a reachability closure, so we can
-		 * avoid including them in the MIDX in that case.
-		 */
-		;
-	}
-
-	strbuf_release(&buf);
-}
-
-static void remove_redundant_bitmaps(struct string_list *include,
-				     const char *packdir)
-{
-	struct strbuf path = STRBUF_INIT;
-	struct string_list_item *item;
-	size_t packdir_len;
-
-	strbuf_addstr(&path, packdir);
-	strbuf_addch(&path, '/');
-	packdir_len = path.len;
-
-	/*
-	 * Remove any pack bitmaps corresponding to packs which are now
-	 * included in the MIDX.
-	 */
-	for_each_string_list_item(item, include) {
-		strbuf_addstr(&path, item->string);
-		strbuf_strip_suffix(&path, ".idx");
-		strbuf_addstr(&path, ".bitmap");
-
-		if (unlink(path.buf) && errno != ENOENT)
-			warning_errno(_("could not remove stale bitmap: %s"),
-				      path.buf);
-
-		strbuf_setlen(&path, packdir_len);
-	}
-	strbuf_release(&path);
-}
-
-static int write_midx_included_packs(struct repack_write_midx_opts *opts)
-{
-	struct child_process cmd = CHILD_PROCESS_INIT;
-	struct string_list include = STRING_LIST_INIT_DUP;
-	struct string_list_item *item;
-	struct packed_git *preferred = pack_geometry_preferred_pack(opts->geometry);
-	FILE *in;
-	int ret = 0;
-
-	midx_included_packs(&include, opts);
-	if (!include.nr)
-		goto done;
-
-	cmd.in = -1;
-	cmd.git_cmd = 1;
-
-	strvec_push(&cmd.args, "multi-pack-index");
-	strvec_pushl(&cmd.args, "write", "--stdin-packs", NULL);
-
-	if (opts->show_progress)
-		strvec_push(&cmd.args, "--progress");
-	else
-		strvec_push(&cmd.args, "--no-progress");
-
-	if (opts->write_bitmaps)
-		strvec_push(&cmd.args, "--bitmap");
-
-	if (preferred)
-		strvec_pushf(&cmd.args, "--preferred-pack=%s",
-			     pack_basename(preferred));
-	else if (opts->names->nr) {
-		/* The largest pack was repacked, meaning that either
-		 * one or two packs exist depending on whether the
-		 * repository has a cruft pack or not.
-		 *
-		 * Select the non-cruft one as preferred to encourage
-		 * pack-reuse among packs containing reachable objects
-		 * over unreachable ones.
-		 *
-		 * (Note we could write multiple packs here if
-		 * `--max-pack-size` was given, but any one of them
-		 * will suffice, so pick the first one.)
-		 */
-		for_each_string_list_item(item, opts->names) {
-			struct generated_pack *pack = item->util;
-			if (generated_pack_has_ext(pack, ".mtimes"))
-				continue;
-
-			strvec_pushf(&cmd.args, "--preferred-pack=pack-%s.pack",
-				     item->string);
-			break;
-		}
-	} else {
-		/*
-		 * No packs were kept, and no packs were written. The
-		 * only thing remaining are .keep packs (unless
-		 * --pack-kept-objects was given).
-		 *
-		 * Set the `--preferred-pack` arbitrarily here.
-		 */
-		;
-	}
-
-	if (opts->refs_snapshot)
-		strvec_pushf(&cmd.args, "--refs-snapshot=%s",
-			     opts->refs_snapshot);
-
-	ret = start_command(&cmd);
-	if (ret)
-		goto done;
-
-	in = xfdopen(cmd.in, "w");
-	for_each_string_list_item(item, &include)
-		fprintf(in, "%s\n", item->string);
-	fclose(in);
-
-	ret = finish_command(&cmd);
-done:
-	if (!ret && opts->write_bitmaps)
-		remove_redundant_bitmaps(&include, opts->packdir);
-
-	string_list_clear(&include, 0);
-
-	return ret;
-}
-
 static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
 				   struct child_process *cmd,
 				   struct string_list *names,
diff --git a/repack-midx.c b/repack-midx.c
index 354df729a5..6f6202c5bc 100644
--- a/repack-midx.c
+++ b/repack-midx.c
@@ -6,6 +6,7 @@
 #include "oidset.h"
 #include "pack-bitmap.h"
 #include "refs.h"
+#include "run-command.h"
 #include "tempfile.h"
 
 struct midx_snapshot_ref_data {
@@ -75,3 +76,297 @@ void midx_snapshot_refs(struct repository *repo, struct tempfile *f)
 
 	oidset_clear(&data.seen);
 }
+
+static int midx_has_unknown_packs(struct string_list *include,
+				  struct pack_geometry *geometry,
+				  struct existing_packs *existing)
+{
+	struct string_list_item *item;
+
+	string_list_sort(include);
+
+	for_each_string_list_item(item, &existing->midx_packs) {
+		const char *pack_name = item->string;
+
+		/*
+		 * Determine whether or not each MIDX'd pack from the existing
+		 * MIDX (if any) is represented in the new MIDX. For each pack
+		 * in the MIDX, it must either be:
+		 *
+		 *  - In the "include" list of packs to be included in the new
+		 *    MIDX. Note this function is called before the include
+		 *    list is populated with any cruft pack(s).
+		 *
+		 *  - Below the geometric split line (if using pack geometry),
+		 *    indicating that the pack won't be included in the new
+		 *    MIDX, but its contents were rolled up as part of the
+		 *    geometric repack.
+		 *
+		 *  - In the existing non-kept packs list (if not using pack
+		 *    geometry), and marked as non-deleted.
+		 */
+		if (string_list_has_string(include, pack_name)) {
+			continue;
+		} else if (geometry) {
+			struct strbuf buf = STRBUF_INIT;
+			uint32_t j;
+
+			for (j = 0; j < geometry->split; j++) {
+				strbuf_reset(&buf);
+				strbuf_addstr(&buf, pack_basename(geometry->pack[j]));
+				strbuf_strip_suffix(&buf, ".pack");
+				strbuf_addstr(&buf, ".idx");
+
+				if (!strcmp(pack_name, buf.buf)) {
+					strbuf_release(&buf);
+					break;
+				}
+			}
+
+			strbuf_release(&buf);
+
+			if (j < geometry->split)
+				continue;
+		} else {
+			struct string_list_item *item;
+
+			item = string_list_lookup(&existing->non_kept_packs,
+						  pack_name);
+			if (item && !existing_pack_is_marked_for_deletion(item))
+				continue;
+		}
+
+		/*
+		 * If we got to this point, the MIDX includes some pack that we
+		 * don't know about.
+		 */
+		return 1;
+	}
+
+	return 0;
+}
+
+static void midx_included_packs(struct string_list *include,
+				struct repack_write_midx_opts *opts)
+{
+	struct existing_packs *existing = opts->existing;
+	struct pack_geometry *geometry = opts->geometry;
+	struct string_list *names = opts->names;
+	struct string_list_item *item;
+	struct strbuf buf = STRBUF_INIT;
+
+	for_each_string_list_item(item, &existing->kept_packs) {
+		strbuf_reset(&buf);
+		strbuf_addf(&buf, "%s.idx", item->string);
+		string_list_insert(include, buf.buf);
+	}
+
+	for_each_string_list_item(item, names) {
+		strbuf_reset(&buf);
+		strbuf_addf(&buf, "pack-%s.idx", item->string);
+		string_list_insert(include, buf.buf);
+	}
+
+	if (geometry->split_factor) {
+		uint32_t i;
+
+		for (i = geometry->split; i < geometry->pack_nr; i++) {
+			struct packed_git *p = geometry->pack[i];
+
+			/*
+			 * The multi-pack index never refers to packfiles part
+			 * of an alternate object database, so we skip these.
+			 * While git-multi-pack-index(1) would silently ignore
+			 * them anyway, this allows us to skip executing the
+			 * command completely when we have only non-local
+			 * packfiles.
+			 */
+			if (!p->pack_local)
+				continue;
+
+			strbuf_reset(&buf);
+			strbuf_addstr(&buf, pack_basename(p));
+			strbuf_strip_suffix(&buf, ".pack");
+			strbuf_addstr(&buf, ".idx");
+
+			string_list_insert(include, buf.buf);
+		}
+	} else {
+		for_each_string_list_item(item, &existing->non_kept_packs) {
+			if (existing_pack_is_marked_for_deletion(item))
+				continue;
+
+			strbuf_reset(&buf);
+			strbuf_addf(&buf, "%s.idx", item->string);
+			string_list_insert(include, buf.buf);
+		}
+	}
+
+	if (opts->midx_must_contain_cruft ||
+	    midx_has_unknown_packs(include, geometry, existing)) {
+		/*
+		 * If there are one or more unknown pack(s) present (see
+		 * midx_has_unknown_packs() for what makes a pack
+		 * "unknown") in the MIDX before the repack, keep them
+		 * as they may be required to form a reachability
+		 * closure if the MIDX is bitmapped.
+		 *
+		 * For example, a cruft pack can be required to form a
+		 * reachability closure if the MIDX is bitmapped and one
+		 * or more of the bitmap's selected commits reaches a
+		 * once-cruft object that was later made reachable.
+		 */
+		for_each_string_list_item(item, &existing->cruft_packs) {
+			/*
+			 * When doing a --geometric repack, there is no
+			 * need to check for deleted packs, since we're
+			 * by definition not doing an ALL_INTO_ONE
+			 * repack (hence no packs will be deleted).
+			 * Otherwise we must check for and exclude any
+			 * packs which are enqueued for deletion.
+			 *
+			 * So we could omit the conditional below in the
+			 * --geometric case, but doing so is unnecessary
+			 *  since no packs are marked as pending
+			 *  deletion (since we only call
+			 *  `existing_packs_mark_for_deletion()` when
+			 *  doing an all-into-one repack).
+			 */
+			if (existing_pack_is_marked_for_deletion(item))
+				continue;
+
+			strbuf_reset(&buf);
+			strbuf_addf(&buf, "%s.idx", item->string);
+			string_list_insert(include, buf.buf);
+		}
+	} else {
+		/*
+		 * Modern versions of Git (with the appropriate
+		 * configuration setting) will write new copies of
+		 * once-cruft objects when doing a --geometric repack.
+		 *
+		 * If the MIDX has no cruft pack, new packs written
+		 * during a --geometric repack will not rely on the
+		 * cruft pack to form a reachability closure, so we can
+		 * avoid including them in the MIDX in that case.
+		 */
+		;
+	}
+
+	strbuf_release(&buf);
+}
+
+static void remove_redundant_bitmaps(struct string_list *include,
+				     const char *packdir)
+{
+	struct strbuf path = STRBUF_INIT;
+	struct string_list_item *item;
+	size_t packdir_len;
+
+	strbuf_addstr(&path, packdir);
+	strbuf_addch(&path, '/');
+	packdir_len = path.len;
+
+	/*
+	 * Remove any pack bitmaps corresponding to packs which are now
+	 * included in the MIDX.
+	 */
+	for_each_string_list_item(item, include) {
+		strbuf_addstr(&path, item->string);
+		strbuf_strip_suffix(&path, ".idx");
+		strbuf_addstr(&path, ".bitmap");
+
+		if (unlink(path.buf) && errno != ENOENT)
+			warning_errno(_("could not remove stale bitmap: %s"),
+				      path.buf);
+
+		strbuf_setlen(&path, packdir_len);
+	}
+	strbuf_release(&path);
+}
+
+int write_midx_included_packs(struct repack_write_midx_opts *opts)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct string_list include = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	struct packed_git *preferred = pack_geometry_preferred_pack(opts->geometry);
+	FILE *in;
+	int ret = 0;
+
+	midx_included_packs(&include, opts);
+	if (!include.nr)
+		goto done;
+
+	cmd.in = -1;
+	cmd.git_cmd = 1;
+
+	strvec_push(&cmd.args, "multi-pack-index");
+	strvec_pushl(&cmd.args, "write", "--stdin-packs", NULL);
+
+	if (opts->show_progress)
+		strvec_push(&cmd.args, "--progress");
+	else
+		strvec_push(&cmd.args, "--no-progress");
+
+	if (opts->write_bitmaps)
+		strvec_push(&cmd.args, "--bitmap");
+
+	if (preferred)
+		strvec_pushf(&cmd.args, "--preferred-pack=%s",
+			     pack_basename(preferred));
+	else if (opts->names->nr) {
+		/* The largest pack was repacked, meaning that either
+		 * one or two packs exist depending on whether the
+		 * repository has a cruft pack or not.
+		 *
+		 * Select the non-cruft one as preferred to encourage
+		 * pack-reuse among packs containing reachable objects
+		 * over unreachable ones.
+		 *
+		 * (Note we could write multiple packs here if
+		 * `--max-pack-size` was given, but any one of them
+		 * will suffice, so pick the first one.)
+		 */
+		for_each_string_list_item(item, opts->names) {
+			struct generated_pack *pack = item->util;
+			if (generated_pack_has_ext(pack, ".mtimes"))
+				continue;
+
+			strvec_pushf(&cmd.args, "--preferred-pack=pack-%s.pack",
+				     item->string);
+			break;
+		}
+	} else {
+		/*
+		 * No packs were kept, and no packs were written. The
+		 * only thing remaining are .keep packs (unless
+		 * --pack-kept-objects was given).
+		 *
+		 * Set the `--preferred-pack` arbitrarily here.
+		 */
+		;
+	}
+
+	if (opts->refs_snapshot)
+		strvec_pushf(&cmd.args, "--refs-snapshot=%s",
+			     opts->refs_snapshot);
+
+	ret = start_command(&cmd);
+	if (ret)
+		goto done;
+
+	in = xfdopen(cmd.in, "w");
+	for_each_string_list_item(item, &include)
+		fprintf(in, "%s\n", item->string);
+	fclose(in);
+
+	ret = finish_command(&cmd);
+done:
+	if (!ret && opts->write_bitmaps)
+		remove_redundant_bitmaps(&include, opts->packdir);
+
+	string_list_clear(&include, 0);
+
+	return ret;
+}
diff --git a/repack.h b/repack.h
index 6aa5b4e0f0..25a31ac0a0 100644
--- a/repack.h
+++ b/repack.h
@@ -101,6 +101,18 @@ void pack_geometry_release(struct pack_geometry *geometry);
 
 struct tempfile;
 
+struct repack_write_midx_opts {
+	struct existing_packs *existing;
+	struct pack_geometry *geometry;
+	struct string_list *names;
+	const char *refs_snapshot;
+	const char *packdir;
+	int show_progress;
+	int write_bitmaps;
+	int midx_must_contain_cruft;
+};
+
 void midx_snapshot_refs(struct repository *repo, struct tempfile *f);
+int write_midx_included_packs(struct repack_write_midx_opts *opts);
 
 #endif /* REPACK_H */

builtin/repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index 5fed79e826..6df7c88085 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -138,9 +138,7 @@ static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
 	return finish_command(cmd);
 }
 
-static int write_filtered_pack(const struct pack_objects_args *args,
-			       const char *destination,
-			       const char *pack_prefix,
+static int write_filtered_pack(struct write_pack_opts *opts,
 			       struct existing_packs *existing,
 			       struct string_list *names)
 {
@@ -150,9 +148,9 @@ static int write_filtered_pack(const struct pack_objects_args *args,
 	int ret;
 	const char *caret;
 	const char *scratch;
-	int local = skip_prefix(destination, packdir, &scratch);
+	int local = skip_prefix(opts->destination, opts->packdir, &scratch);
 
-	prepare_pack_objects(&cmd, args, destination);
+	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
 
 	strvec_push(&cmd.args, "--stdin-packs");
 
@@ -175,7 +173,7 @@ static int write_filtered_pack(const struct pack_objects_args *args,
 	 */
 	in = xfdopen(cmd.in, "w");
 	for_each_string_list_item(item, names)
-		fprintf(in, "^%s-%s.pack\n", pack_prefix, item->string);
+		fprintf(in, "^%s-%s.pack\n", opts->pack_prefix, item->string);
 	for_each_string_list_item(item, &existing->non_kept_packs)
 		fprintf(in, "%s.pack\n", item->string);
 	for_each_string_list_item(item, &existing->cruft_packs)
@@ -665,14 +663,18 @@ int cmd_repack(int argc,
 	}
 
 	if (po_args.filter_options.choice) {
-		if (!filter_to)
-			filter_to = packtmp;
+		struct write_pack_opts opts = {
+			.po_args = &po_args,
+			.destination = filter_to,
+			.pack_prefix = find_pack_prefix(packdir, packtmp),
+			.packdir = packdir,
+			.packtmp = packtmp,
+		};
 
-		ret = write_filtered_pack(&po_args,
-					  filter_to,
-					  find_pack_prefix(packdir, packtmp),
-					  &existing,
-					  &names);
+		if (!opts.destination)
+			opts.destination = packtmp;
+
+		ret = write_filtered_pack(&opts, &existing, &names);
 		if (ret)
 			goto cleanup;
 	}
diff --git a/repack.h b/repack.h
index 25a31ac0a0..6ef503f623 100644
--- a/repack.h
+++ b/repack.h
@@ -32,6 +32,14 @@ void pack_objects_args_release(struct pack_objects_args *args);
 void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
 				  const char *base_name);
 
+struct write_pack_opts {
+	struct pack_objects_args *po_args;
+	const char *destination;
+	const char *pack_prefix;
+	const char *packdir;
+	const char *packtmp;
+};
+
 struct repository;
 struct packed_git;
 

diff --git a/builtin/repack.c b/builtin/repack.c
index 6df7c88085..501359c580 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -221,9 +221,7 @@ static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
 	strbuf_release(&buf);
 }
 
-static int write_cruft_pack(const struct pack_objects_args *args,
-			    const char *destination,
-			    const char *pack_prefix,
+static int write_cruft_pack(struct write_pack_opts *opts,
 			    const char *cruft_expiration,
 			    unsigned long combine_cruft_below_size,
 			    struct string_list *names,
@@ -234,9 +232,9 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 	FILE *in;
 	int ret;
 	const char *scratch;
-	int local = skip_prefix(destination, packdir, &scratch);
+	int local = skip_prefix(opts->destination, opts->packdir, &scratch);
 
-	prepare_pack_objects(&cmd, args, destination);
+	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
 
 	strvec_push(&cmd.args, "--cruft");
 	if (cruft_expiration)
@@ -267,7 +265,7 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 	 */
 	in = xfdopen(cmd.in, "w");
 	for_each_string_list_item(item, names)
-		fprintf(in, "%s-%s.pack\n", pack_prefix, item->string);
+		fprintf(in, "%s-%s.pack\n", opts->pack_prefix, item->string);
 	if (combine_cruft_below_size && !cruft_expiration) {
 		combine_small_cruft_packs(in, combine_cruft_below_size,
 					  existing);
@@ -599,6 +597,13 @@ int cmd_repack(int argc,
 
 	if (pack_everything & PACK_CRUFT) {
 		const char *pack_prefix = find_pack_prefix(packdir, packtmp);
+		struct write_pack_opts opts = {
+			.po_args = &cruft_po_args,
+			.destination = packtmp,
+			.pack_prefix = pack_prefix,
+			.packtmp = packtmp,
+			.packdir = packdir,
+		};
 
 		if (!cruft_po_args.window)
 			cruft_po_args.window = xstrdup_or_null(po_args.window);
@@ -615,8 +620,7 @@ int cmd_repack(int argc,
 		cruft_po_args.quiet = po_args.quiet;
 		cruft_po_args.delta_base_offset = po_args.delta_base_offset;
 
-		ret = write_cruft_pack(&cruft_po_args, packtmp, pack_prefix,
-				       cruft_expiration,
+		ret = write_cruft_pack(&opts, cruft_expiration,
 				       combine_cruft_below_size, &names,
 				       &existing);
 		if (ret)
@@ -651,11 +655,8 @@ int cmd_repack(int argc,
 			 * pack, but rather removing all cruft packs from the
 			 * main repository regardless of size.
 			 */
-			ret = write_cruft_pack(&cruft_po_args, expire_to,
-					       pack_prefix,
-					       NULL,
-					       0ul,
-					       &names,
+			opts.destination = expire_to;
+			ret = write_cruft_pack(&opts, NULL, 0ul, &names,
 					       &existing);
 			if (ret)
 				goto cleanup;

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index 501359c580..4d86920618 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -149,6 +149,7 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 	const char *caret;
 	const char *scratch;
 	int local = skip_prefix(opts->destination, opts->packdir, &scratch);
+	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
 
 	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
 
@@ -173,7 +174,7 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 	 */
 	in = xfdopen(cmd.in, "w");
 	for_each_string_list_item(item, names)
-		fprintf(in, "^%s-%s.pack\n", opts->pack_prefix, item->string);
+		fprintf(in, "^%s-%s.pack\n", pack_prefix, item->string);
 	for_each_string_list_item(item, &existing->non_kept_packs)
 		fprintf(in, "%s.pack\n", item->string);
 	for_each_string_list_item(item, &existing->cruft_packs)
@@ -233,6 +234,7 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 	int ret;
 	const char *scratch;
 	int local = skip_prefix(opts->destination, opts->packdir, &scratch);
+	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
 
 	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
 
@@ -265,7 +267,7 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 	 */
 	in = xfdopen(cmd.in, "w");
 	for_each_string_list_item(item, names)
-		fprintf(in, "%s-%s.pack\n", opts->pack_prefix, item->string);
+		fprintf(in, "%s-%s.pack\n", pack_prefix, item->string);
 	if (combine_cruft_below_size && !cruft_expiration) {
 		combine_small_cruft_packs(in, combine_cruft_below_size,
 					  existing);
@@ -283,17 +285,6 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 				       local);
 }
 
-static const char *find_pack_prefix(const char *packdir, const char *packtmp)
-{
-	const char *pack_prefix;
-	if (!skip_prefix(packtmp, packdir, &pack_prefix))
-		die(_("pack prefix %s does not begin with objdir %s"),
-		    packtmp, packdir);
-	if (*pack_prefix == '/')
-		pack_prefix++;
-	return pack_prefix;
-}
-
 int cmd_repack(int argc,
 	       const char **argv,
 	       const char *prefix,
@@ -596,11 +587,9 @@ int cmd_repack(int argc,
 	}
 
 	if (pack_everything & PACK_CRUFT) {
-		const char *pack_prefix = find_pack_prefix(packdir, packtmp);
 		struct write_pack_opts opts = {
 			.po_args = &cruft_po_args,
 			.destination = packtmp,
-			.pack_prefix = pack_prefix,
 			.packtmp = packtmp,
 			.packdir = packdir,
 		};
@@ -667,7 +656,6 @@ int cmd_repack(int argc,
 		struct write_pack_opts opts = {
 			.po_args = &po_args,
 			.destination = filter_to,
-			.pack_prefix = find_pack_prefix(packdir, packtmp),
 			.packdir = packdir,
 			.packtmp = packtmp,
 		};
diff --git a/repack.c b/repack.c
index 1d485e0112..c4326a532d 100644
--- a/repack.c
+++ b/repack.c
@@ -66,6 +66,17 @@ void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
 	strbuf_release(&buf);
 }
 
+const char *write_pack_opts_pack_prefix(struct write_pack_opts *opts)
+{
+	const char *pack_prefix;
+	if (!skip_prefix(opts->packtmp, opts->packdir, &pack_prefix))
+		die(_("pack prefix %s does not begin with objdir %s"),
+		    opts->packtmp, opts->packdir);
+	if (*pack_prefix == '/')
+		pack_prefix++;
+	return pack_prefix;
+}
+
 #define DELETE_PACK 1
 #define RETAIN_PACK 2
 
diff --git a/repack.h b/repack.h
index 6ef503f623..46d2312fa9 100644
--- a/repack.h
+++ b/repack.h
@@ -35,11 +35,12 @@ void repack_remove_redundant_pack(struct repository *repo, const char *dir_name,
 struct write_pack_opts {
 	struct pack_objects_args *po_args;
 	const char *destination;
-	const char *pack_prefix;
 	const char *packdir;
 	const char *packtmp;
 };
 
+const char *write_pack_opts_pack_prefix(struct write_pack_opts *opts);
+
 struct repository;
 struct packed_git;
 

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index 4d86920618..be8e6689fc 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -147,8 +147,7 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 	FILE *in;
 	int ret;
 	const char *caret;
-	const char *scratch;
-	int local = skip_prefix(opts->destination, opts->packdir, &scratch);
+	int local = write_pack_opts_is_local(opts);
 	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
 
 	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
@@ -232,8 +231,7 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 	struct string_list_item *item;
 	FILE *in;
 	int ret;
-	const char *scratch;
-	int local = skip_prefix(opts->destination, opts->packdir, &scratch);
+	int local = write_pack_opts_is_local(opts);
 	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
 
 	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
diff --git a/repack.c b/repack.c
index c4326a532d..7af297ae48 100644
--- a/repack.c
+++ b/repack.c
@@ -77,6 +77,12 @@ const char *write_pack_opts_pack_prefix(struct write_pack_opts *opts)
 	return pack_prefix;
 }
 
+int write_pack_opts_is_local(struct write_pack_opts *opts)
+{
+	const char *scratch;
+	return skip_prefix(opts->destination, opts->packdir, &scratch);
+}
+
 #define DELETE_PACK 1
 #define RETAIN_PACK 2
 
diff --git a/repack.h b/repack.h
index 46d2312fa9..16f2de2ea9 100644
--- a/repack.h
+++ b/repack.h
@@ -40,6 +40,7 @@ struct write_pack_opts {
 };
 
 const char *write_pack_opts_pack_prefix(struct write_pack_opts *opts);
+int write_pack_opts_is_local(struct write_pack_opts *opts);
 
 struct repository;
 struct packed_git;

diff --git a/builtin/repack.c b/builtin/repack.c
index be8e6689fc..8db95305c8 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -108,11 +108,12 @@ static int repack_config(const char *var, const char *value,
 }
 
 static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
+				   struct write_pack_opts *opts,
 				   struct child_process *cmd,
-				   struct string_list *names,
-				   int local)
+				   struct string_list *names)
 {
 	FILE *out;
+	int local = write_pack_opts_is_local(opts);
 	struct strbuf line = STRBUF_INIT;
 
 	out = xfdopen(cmd->out, "r");
@@ -128,7 +129,8 @@ static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
 		 */
 		if (local) {
 			item = string_list_append(names, line.buf);
-			item->util = generated_pack_populate(line.buf, packtmp);
+			item->util = generated_pack_populate(line.buf,
+							     opts->packtmp);
 		}
 	}
 	fclose(out);
@@ -147,7 +149,6 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 	FILE *in;
 	int ret;
 	const char *caret;
-	int local = write_pack_opts_is_local(opts);
 	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
 
 	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
@@ -183,8 +184,8 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 		fprintf(in, "%s%s.pack\n", caret, item->string);
 	fclose(in);
 
-	return finish_pack_objects_cmd(existing->repo->hash_algo, &cmd, names,
-				       local);
+	return finish_pack_objects_cmd(existing->repo->hash_algo, opts, &cmd,
+				       names);
 }
 
 static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
@@ -231,7 +232,6 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 	struct string_list_item *item;
 	FILE *in;
 	int ret;
-	int local = write_pack_opts_is_local(opts);
 	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
 
 	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
@@ -279,8 +279,8 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 		fprintf(in, "%s.pack\n", item->string);
 	fclose(in);
 
-	return finish_pack_objects_cmd(existing->repo->hash_algo, &cmd, names,
-				       local);
+	return finish_pack_objects_cmd(existing->repo->hash_algo, opts, &cmd,
+				       names);
 }
 
 int cmd_repack(int argc,
@@ -294,6 +294,7 @@ int cmd_repack(int argc,
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
 	struct tempfile *refs_snapshot = NULL;
+	struct write_pack_opts opts = { 0 };
 	int i, ret;
 	int show_progress;
 
@@ -560,7 +561,10 @@ int cmd_repack(int argc,
 		fclose(in);
 	}
 
-	ret = finish_pack_objects_cmd(repo->hash_algo, &cmd, &names, 1);
+	opts.packdir = packdir;
+	opts.destination = packdir;
+	opts.packtmp = packtmp;
+	ret = finish_pack_objects_cmd(repo->hash_algo, &opts, &cmd, &names);
 	if (ret)
 		goto cleanup;
 

diff --git a/builtin/repack.c b/builtin/repack.c
index ad60c4290d..4e4519b180 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -108,7 +108,6 @@ int cmd_repack(int argc,
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
 	struct tempfile *refs_snapshot = NULL;
-	struct write_pack_opts opts = { 0 };
 	int i, ret;
 	int show_progress;
 
@@ -372,12 +371,15 @@ int cmd_repack(int argc,
 		fclose(in);
 	}
 
-	opts.packdir = packdir;
-	opts.destination = packdir;
-	opts.packtmp = packtmp;
-	ret = finish_pack_objects_cmd(repo->hash_algo, &opts, &cmd, &names);
-	if (ret)
-		goto cleanup;
+	{
+		struct write_pack_opts opts = { 0 };
+		opts.packdir = packdir;
+		opts.destination = packdir;
+		opts.packtmp = packtmp;
+		ret = finish_pack_objects_cmd(repo->hash_algo, &opts, &cmd, &names);
+		if (ret)
+			goto cleanup;
+	}
 
 	if (!names.nr) {
 		if (!po_args.quiet)

That might be nice, but introducing the extra block is kind of ugly. Of
course you can get really fancy with a compound literal, like:

@@ -372,10 +371,13 @@ int cmd_repack(int argc,
 		fclose(in);
 	}
 
-	opts.packdir = packdir;
-	opts.destination = packdir;
-	opts.packtmp = packtmp;
-	ret = finish_pack_objects_cmd(repo->hash_algo, &opts, &cmd, &names);
+	ret = finish_pack_objects_cmd(repo->hash_algo,
+				      &(struct write_pack_opts) {
+					.packdir = packdir,
+					.destination = packdir,
+					.packtmp = packtmp,
+				      },
+				      &cmd, &names);
 	if (ret)
 		goto cleanup;
 

But that may be a bridge too far.

-Peff

builtin/repack.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index 8db95305c8..836a006607 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -107,39 +107,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-static int finish_pack_objects_cmd(const struct git_hash_algo *algop,
-				   struct write_pack_opts *opts,
-				   struct child_process *cmd,
-				   struct string_list *names)
-{
-	FILE *out;
-	int local = write_pack_opts_is_local(opts);
-	struct strbuf line = STRBUF_INIT;
-
-	out = xfdopen(cmd->out, "r");
-	while (strbuf_getline_lf(&line, out) != EOF) {
-		struct string_list_item *item;
-
-		if (line.len != algop->hexsz)
-			die(_("repack: Expecting full hex object ID lines only "
-			      "from pack-objects."));
-		/*
-		 * Avoid putting packs written outside of the repository in the
-		 * list of names.
-		 */
-		if (local) {
-			item = string_list_append(names, line.buf);
-			item->util = generated_pack_populate(line.buf,
-							     opts->packtmp);
-		}
-	}
-	fclose(out);
-
-	strbuf_release(&line);
-
-	return finish_command(cmd);
-}
-
 static int write_filtered_pack(struct write_pack_opts *opts,
 			       struct existing_packs *existing,
 			       struct string_list *names)
diff --git a/repack.c b/repack.c
index 7af297ae48..8a0e4789fa 100644
--- a/repack.c
+++ b/repack.c
@@ -83,6 +83,39 @@ int write_pack_opts_is_local(struct write_pack_opts *opts)
 	return skip_prefix(opts->destination, opts->packdir, &scratch);
 }
 
+int finish_pack_objects_cmd(const struct git_hash_algo *algop,
+			    struct write_pack_opts *opts,
+			    struct child_process *cmd,
+			    struct string_list *names)
+{
+	FILE *out;
+	int local = write_pack_opts_is_local(opts);
+	struct strbuf line = STRBUF_INIT;
+
+	out = xfdopen(cmd->out, "r");
+	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+
+		if (line.len != algop->hexsz)
+			die(_("repack: Expecting full hex object ID lines only "
+			      "from pack-objects."));
+		/*
+		 * Avoid putting packs written outside of the repository in the
+		 * list of names.
+		 */
+		if (local) {
+			item = string_list_append(names, line.buf);
+			item->util = generated_pack_populate(line.buf,
+							     opts->packtmp);
+		}
+	}
+	fclose(out);
+
+	strbuf_release(&line);
+
+	return finish_command(cmd);
+}
+
 #define DELETE_PACK 1
 #define RETAIN_PACK 2
 
diff --git a/repack.h b/repack.h
index 16f2de2ea9..9351293233 100644
--- a/repack.h
+++ b/repack.h
@@ -42,6 +42,11 @@ struct write_pack_opts {
 const char *write_pack_opts_pack_prefix(struct write_pack_opts *opts);
 int write_pack_opts_is_local(struct write_pack_opts *opts);
 
+int finish_pack_objects_cmd(const struct git_hash_algo *algop,
+			    struct write_pack_opts *opts,
+			    struct child_process *cmd,
+			    struct string_list *names);
+
 struct repository;
 struct packed_git;
 

builtin/repack.c, repack-geometry.c, repack.c, repack.h

diff --git a/builtin/repack.c b/builtin/repack.c
index 836a006607..9d89217b77 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -33,7 +33,6 @@
 #define RETAIN_PACK 2
 
 static int pack_everything;
-static int pack_kept_objects = -1;
 static int write_bitmaps = -1;
 static int use_delta_islands;
 static int run_update_server_info = 1;
@@ -68,7 +67,7 @@ static int repack_config(const char *var, const char *value,
 		return 0;
 	}
 	if (!strcmp(var, "repack.packkeptobjects")) {
-		pack_kept_objects = git_config_bool(var, value);
+		po_args->pack_kept_objects = git_config_bool(var, value);
 		return 0;
 	}
 	if (!strcmp(var, "repack.writebitmaps") ||
@@ -122,8 +121,6 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 
 	strvec_push(&cmd.args, "--stdin-packs");
 
-	if (!pack_kept_objects)
-		strvec_push(&cmd.args, "--honor-pack-keep");
 	for_each_string_list_item(item, &existing->kept_packs)
 		strvec_pushf(&cmd.args, "--keep-pack=%s", item->string);
 
@@ -146,7 +143,7 @@ static int write_filtered_pack(struct write_pack_opts *opts,
 		fprintf(in, "%s.pack\n", item->string);
 	for_each_string_list_item(item, &existing->cruft_packs)
 		fprintf(in, "%s.pack\n", item->string);
-	caret = pack_kept_objects ? "" : "^";
+	caret = opts->po_args->pack_kept_objects ? "" : "^";
 	for_each_string_list_item(item, &existing->kept_packs)
 		fprintf(in, "%s%s.pack\n", caret, item->string);
 	fclose(in);
@@ -208,7 +205,6 @@ static int write_cruft_pack(struct write_pack_opts *opts,
 		strvec_pushf(&cmd.args, "--cruft-expiration=%s",
 			     cruft_expiration);
 
-	strvec_push(&cmd.args, "--honor-pack-keep");
 	strvec_push(&cmd.args, "--non-empty");
 
 	cmd.in = -1;
@@ -333,7 +329,7 @@ int cmd_repack(int argc,
 		OPT_UNSIGNED(0, "max-pack-size", &po_args.max_pack_size,
 			     N_("maximum size of each packfile")),
 		OPT_PARSE_LIST_OBJECTS_FILTER(&po_args.filter_options),
-		OPT_BOOL(0, "pack-kept-objects", &pack_kept_objects,
+		OPT_BOOL(0, "pack-kept-objects", &po_args.pack_kept_objects,
 				N_("repack objects in packs marked with .keep")),
 		OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
 				N_("do not repack this pack")),
@@ -379,8 +375,8 @@ int cmd_repack(int argc,
 		    (!(pack_everything & ALL_INTO_ONE) || !is_bare_repository()))
 			write_bitmaps = 0;
 	}
-	if (pack_kept_objects < 0)
-		pack_kept_objects = write_bitmaps > 0 && !write_midx;
+	if (po_args.pack_kept_objects < 0)
+		po_args.pack_kept_objects = write_bitmaps > 0 && !write_midx;
 
 	if (write_bitmaps && !(pack_everything & ALL_INTO_ONE) && !write_midx)
 		die(_(incremental_bitmap_conflict_error));
@@ -421,8 +417,7 @@ int cmd_repack(int argc,
 	if (geometry.split_factor) {
 		if (pack_everything)
 			die(_("options '%s' and '%s' cannot be used together"), "--geometric", "-A/-a");
-		pack_geometry_init(&geometry, &existing, &po_args,
-				   pack_kept_objects);
+		pack_geometry_init(&geometry, &existing, &po_args);
 		pack_geometry_split(&geometry);
 	}
 
@@ -431,8 +426,6 @@ int cmd_repack(int argc,
 	show_progress = !po_args.quiet && isatty(2);
 
 	strvec_push(&cmd.args, "--keep-true-parents");
-	if (!pack_kept_objects)
-		strvec_push(&cmd.args, "--honor-pack-keep");
 	for (i = 0; i < keep_pack_list.nr; i++)
 		strvec_pushf(&cmd.args, "--keep-pack=%s",
 			     keep_pack_list.items[i].string);
@@ -577,6 +570,7 @@ int cmd_repack(int argc,
 		cruft_po_args.local = po_args.local;
 		cruft_po_args.quiet = po_args.quiet;
 		cruft_po_args.delta_base_offset = po_args.delta_base_offset;
+		cruft_po_args.pack_kept_objects = 0;
 
 		ret = write_cruft_pack(&opts, cruft_expiration,
 				       combine_cruft_below_size, &names,
diff --git a/repack-geometry.c b/repack-geometry.c
index a879f2fe49..fd4a89a115 100644
--- a/repack-geometry.c
+++ b/repack-geometry.c
@@ -26,8 +26,7 @@ static int pack_geometry_cmp(const void *va, const void *vb)
 
 void pack_geometry_init(struct pack_geometry *geometry,
 			struct existing_packs *existing,
-			const struct pack_objects_args *args,
-			int pack_kept_objects)
+			const struct pack_objects_args *args)
 {
 	struct packfile_store *packs = existing->repo->objects->packfiles;
 	struct packed_git *p;
@@ -42,7 +41,7 @@ void pack_geometry_init(struct pack_geometry *geometry,
 			 */
 			continue;
 
-		if (!pack_kept_objects) {
+		if (!args->pack_kept_objects) {
 			/*
 			 * Any pack that has its pack_keep bit set will
 			 * appear in existing->kept_packs below, but
diff --git a/repack.c b/repack.c
index 8a0e4789fa..1982a48165 100644
--- a/repack.c
+++ b/repack.c
@@ -38,6 +38,8 @@ void prepare_pack_objects(struct child_process *cmd,
 		strvec_push(&cmd->args,  "--quiet");
 	if (args->delta_base_offset)
 		strvec_push(&cmd->args,  "--delta-base-offset");
+	if (!args->pack_kept_objects)
+		strvec_push(&cmd->args,  "--honor-pack-keep");
 	strvec_push(&cmd->args, out);
 	cmd->git_cmd = 1;
 	cmd->out = -1;
diff --git a/repack.h b/repack.h
index 9351293233..4a1c4eb606 100644
--- a/repack.h
+++ b/repack.h
@@ -17,10 +17,14 @@ struct pack_objects_args {
 	int name_hash_version;
 	int path_walk;
 	int delta_base_offset;
+	int pack_kept_objects;
 	struct list_objects_filter_options filter_options;
 };
 
-#define PACK_OBJECTS_ARGS_INIT { .delta_base_offset = 1 }
+#define PACK_OBJECTS_ARGS_INIT { \
+	.delta_base_offset = 1, \
+	.pack_kept_objects = -1, \
+}
 
 struct child_process;
 
@@ -104,8 +108,7 @@ struct pack_geometry {
 
 void pack_geometry_init(struct pack_geometry *geometry,
 			struct existing_packs *existing,
-			const struct pack_objects_args *args,
-			int pack_kept_objects);
+			const struct pack_objects_args *args);
 void pack_geometry_split(struct pack_geometry *geometry);
 struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geometry);
 void pack_geometry_remove_redundant(struct pack_geometry *geometry,

Makefile, builtin/repack.c, meson.build, repack-filtered.c, repack.h

diff --git a/Makefile b/Makefile
index 3360743afb..1e2c09da07 100644
--- a/Makefile
+++ b/Makefile
@@ -1137,6 +1137,7 @@ LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
+LIB_OBJS += repack-filtered.o
 LIB_OBJS += repack-geometry.o
 LIB_OBJS += repack-midx.o
 LIB_OBJS += repack-promisor.o
diff --git a/builtin/repack.c b/builtin/repack.c
index 9d89217b77..a9fc09a24d 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -106,52 +106,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-static int write_filtered_pack(struct write_pack_opts *opts,
-			       struct existing_packs *existing,
-			       struct string_list *names)
-{
-	struct child_process cmd = CHILD_PROCESS_INIT;
-	struct string_list_item *item;
-	FILE *in;
-	int ret;
-	const char *caret;
-	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
-
-	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
-
-	strvec_push(&cmd.args, "--stdin-packs");
-
-	for_each_string_list_item(item, &existing->kept_packs)
-		strvec_pushf(&cmd.args, "--keep-pack=%s", item->string);
-
-	cmd.in = -1;
-
-	ret = start_command(&cmd);
-	if (ret)
-		return ret;
-
-	/*
-	 * Here 'names' contains only the pack(s) that were just
-	 * written, which is exactly the packs we want to keep. Also
-	 * 'existing_kept_packs' already contains the packs in
-	 * 'keep_pack_list'.
-	 */
-	in = xfdopen(cmd.in, "w");
-	for_each_string_list_item(item, names)
-		fprintf(in, "^%s-%s.pack\n", pack_prefix, item->string);
-	for_each_string_list_item(item, &existing->non_kept_packs)
-		fprintf(in, "%s.pack\n", item->string);
-	for_each_string_list_item(item, &existing->cruft_packs)
-		fprintf(in, "%s.pack\n", item->string);
-	caret = opts->po_args->pack_kept_objects ? "" : "^";
-	for_each_string_list_item(item, &existing->kept_packs)
-		fprintf(in, "%s%s.pack\n", caret, item->string);
-	fclose(in);
-
-	return finish_pack_objects_cmd(existing->repo->hash_algo, opts, &cmd,
-				       names);
-}
-
 static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
 				      struct existing_packs *existing)
 {
diff --git a/meson.build b/meson.build
index 42171d1851..4c60e016c3 100644
--- a/meson.build
+++ b/meson.build
@@ -463,6 +463,7 @@ libgit_sources = [
   'reftable/writer.c',
   'remote.c',
   'repack.c',
+  'repack-filtered.c',
   'repack-geometry.c',
   'repack-midx.c',
   'repack-promisor.c',
diff --git a/repack-filtered.c b/repack-filtered.c
new file mode 100644
index 0000000000..96c7b02bb6
--- /dev/null
+++ b/repack-filtered.c
@@ -0,0 +1,51 @@
+#include "git-compat-util.h"
+#include "repack.h"
+#include "repository.h"
+#include "run-command.h"
+#include "string-list.h"
+
+int write_filtered_pack(struct write_pack_opts *opts,
+			struct existing_packs *existing,
+			struct string_list *names)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct string_list_item *item;
+	FILE *in;
+	int ret;
+	const char *caret;
+	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
+
+	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
+
+	strvec_push(&cmd.args, "--stdin-packs");
+
+	for_each_string_list_item(item, &existing->kept_packs)
+		strvec_pushf(&cmd.args, "--keep-pack=%s", item->string);
+
+	cmd.in = -1;
+
+	ret = start_command(&cmd);
+	if (ret)
+		return ret;
+
+	/*
+	 * Here 'names' contains only the pack(s) that were just
+	 * written, which is exactly the packs we want to keep. Also
+	 * 'existing_kept_packs' already contains the packs in
+	 * 'keep_pack_list'.
+	 */
+	in = xfdopen(cmd.in, "w");
+	for_each_string_list_item(item, names)
+		fprintf(in, "^%s-%s.pack\n", pack_prefix, item->string);
+	for_each_string_list_item(item, &existing->non_kept_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	for_each_string_list_item(item, &existing->cruft_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	caret = opts->po_args->pack_kept_objects ? "" : "^";
+	for_each_string_list_item(item, &existing->kept_packs)
+		fprintf(in, "%s%s.pack\n", caret, item->string);
+	fclose(in);
+
+	return finish_pack_objects_cmd(existing->repo->hash_algo, opts, &cmd,
+				       names);
+}
diff --git a/repack.h b/repack.h
index 4a1c4eb606..a7ddbe784b 100644
--- a/repack.h
+++ b/repack.h
@@ -133,4 +133,8 @@ struct repack_write_midx_opts {
 void midx_snapshot_refs(struct repository *repo, struct tempfile *f);
 int write_midx_included_packs(struct repack_write_midx_opts *opts);
 
+int write_filtered_pack(struct write_pack_opts *opts,
+			struct existing_packs *existing,
+			struct string_list *names);
+
 #endif /* REPACK_H */

Makefile, builtin/repack.c, meson.build, repack-cruft.c, repack.h

diff --git a/Makefile b/Makefile
index 1e2c09da07..72d7a4686f 100644
--- a/Makefile
+++ b/Makefile
@@ -1137,6 +1137,7 @@ LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
+LIB_OBJS += repack-cruft.o
 LIB_OBJS += repack-filtered.o
 LIB_OBJS += repack-geometry.o
 LIB_OBJS += repack-midx.o
diff --git a/builtin/repack.c b/builtin/repack.c
index a9fc09a24d..9171ca66a7 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -106,100 +106,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-static void combine_small_cruft_packs(FILE *in, size_t combine_cruft_below_size,
-				      struct existing_packs *existing)
-{
-	struct packfile_store *packs = existing->repo->objects->packfiles;
-	struct packed_git *p;
-	struct strbuf buf = STRBUF_INIT;
-	size_t i;
-
-	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
-		if (!(p->is_cruft && p->pack_local))
-			continue;
-
-		strbuf_reset(&buf);
-		strbuf_addstr(&buf, pack_basename(p));
-		strbuf_strip_suffix(&buf, ".pack");
-
-		if (!string_list_has_string(&existing->cruft_packs, buf.buf))
-			continue;
-
-		if (p->pack_size < combine_cruft_below_size) {
-			fprintf(in, "-%s\n", pack_basename(p));
-		} else {
-			existing_packs_retain_cruft(existing, p);
-			fprintf(in, "%s\n", pack_basename(p));
-		}
-	}
-
-	for (i = 0; i < existing->non_kept_packs.nr; i++)
-		fprintf(in, "-%s.pack\n",
-			existing->non_kept_packs.items[i].string);
-
-	strbuf_release(&buf);
-}
-
-static int write_cruft_pack(struct write_pack_opts *opts,
-			    const char *cruft_expiration,
-			    unsigned long combine_cruft_below_size,
-			    struct string_list *names,
-			    struct existing_packs *existing)
-{
-	struct child_process cmd = CHILD_PROCESS_INIT;
-	struct string_list_item *item;
-	FILE *in;
-	int ret;
-	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
-
-	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
-
-	strvec_push(&cmd.args, "--cruft");
-	if (cruft_expiration)
-		strvec_pushf(&cmd.args, "--cruft-expiration=%s",
-			     cruft_expiration);
-
-	strvec_push(&cmd.args, "--non-empty");
-
-	cmd.in = -1;
-
-	ret = start_command(&cmd);
-	if (ret)
-		return ret;
-
-	/*
-	 * names has a confusing double use: it both provides the list
-	 * of just-written new packs, and accepts the name of the cruft
-	 * pack we are writing.
-	 *
-	 * By the time it is read here, it contains only the pack(s)
-	 * that were just written, which is exactly the set of packs we
-	 * want to consider kept.
-	 *
-	 * If `--expire-to` is given, the double-use served by `names`
-	 * ensures that the pack written to `--expire-to` excludes any
-	 * objects contained in the cruft pack.
-	 */
-	in = xfdopen(cmd.in, "w");
-	for_each_string_list_item(item, names)
-		fprintf(in, "%s-%s.pack\n", pack_prefix, item->string);
-	if (combine_cruft_below_size && !cruft_expiration) {
-		combine_small_cruft_packs(in, combine_cruft_below_size,
-					  existing);
-	} else {
-		for_each_string_list_item(item, &existing->non_kept_packs)
-			fprintf(in, "-%s.pack\n", item->string);
-		for_each_string_list_item(item, &existing->cruft_packs)
-			fprintf(in, "-%s.pack\n", item->string);
-	}
-	for_each_string_list_item(item, &existing->kept_packs)
-		fprintf(in, "%s.pack\n", item->string);
-	fclose(in);
-
-	return finish_pack_objects_cmd(existing->repo->hash_algo, opts, &cmd,
-				       names);
-}
-
 int cmd_repack(int argc,
 	       const char **argv,
 	       const char *prefix,
diff --git a/meson.build b/meson.build
index 4c60e016c3..2993b767dc 100644
--- a/meson.build
+++ b/meson.build
@@ -463,6 +463,7 @@ libgit_sources = [
   'reftable/writer.c',
   'remote.c',
   'repack.c',
+  'repack-cruft.c',
   'repack-filtered.c',
   'repack-geometry.c',
   'repack-midx.c',
diff --git a/repack-cruft.c b/repack-cruft.c
new file mode 100644
index 0000000000..accb98bcdb
--- /dev/null
+++ b/repack-cruft.c
@@ -0,0 +1,99 @@
+#include "git-compat-util.h"
+#include "repack.h"
+#include "packfile.h"
+#include "repository.h"
+#include "run-command.h"
+
+static void combine_small_cruft_packs(FILE *in, off_t combine_cruft_below_size,
+				      struct existing_packs *existing)
+{
+	struct packfile_store *packs = existing->repo->objects->packfiles;
+	struct packed_git *p;
+	struct strbuf buf = STRBUF_INIT;
+	size_t i;
+
+	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
+		if (!(p->is_cruft && p->pack_local))
+			continue;
+
+		strbuf_reset(&buf);
+		strbuf_addstr(&buf, pack_basename(p));
+		strbuf_strip_suffix(&buf, ".pack");
+
+		if (!string_list_has_string(&existing->cruft_packs, buf.buf))
+			continue;
+
+		if (p->pack_size < combine_cruft_below_size) {
+			fprintf(in, "-%s\n", pack_basename(p));
+		} else {
+			existing_packs_retain_cruft(existing, p);
+			fprintf(in, "%s\n", pack_basename(p));
+		}
+	}
+
+	for (i = 0; i < existing->non_kept_packs.nr; i++)
+		fprintf(in, "-%s.pack\n",
+			existing->non_kept_packs.items[i].string);
+
+	strbuf_release(&buf);
+}
+
+int write_cruft_pack(struct write_pack_opts *opts,
+		     const char *cruft_expiration,
+		     unsigned long combine_cruft_below_size,
+		     struct string_list *names,
+		     struct existing_packs *existing)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct string_list_item *item;
+	FILE *in;
+	int ret;
+	const char *pack_prefix = write_pack_opts_pack_prefix(opts);
+
+	prepare_pack_objects(&cmd, opts->po_args, opts->destination);
+
+	strvec_push(&cmd.args, "--cruft");
+	if (cruft_expiration)
+		strvec_pushf(&cmd.args, "--cruft-expiration=%s",
+			     cruft_expiration);
+
+	strvec_push(&cmd.args, "--non-empty");
+
+	cmd.in = -1;
+
+	ret = start_command(&cmd);
+	if (ret)
+		return ret;
+
+	/*
+	 * names has a confusing double use: it both provides the list
+	 * of just-written new packs, and accepts the name of the cruft
+	 * pack we are writing.
+	 *
+	 * By the time it is read here, it contains only the pack(s)
+	 * that were just written, which is exactly the set of packs we
+	 * want to consider kept.
+	 *
+	 * If `--expire-to` is given, the double-use served by `names`
+	 * ensures that the pack written to `--expire-to` excludes any
+	 * objects contained in the cruft pack.
+	 */
+	in = xfdopen(cmd.in, "w");
+	for_each_string_list_item(item, names)
+		fprintf(in, "%s-%s.pack\n", pack_prefix, item->string);
+	if (combine_cruft_below_size && !cruft_expiration) {
+		combine_small_cruft_packs(in, combine_cruft_below_size,
+					  existing);
+	} else {
+		for_each_string_list_item(item, &existing->non_kept_packs)
+			fprintf(in, "-%s.pack\n", item->string);
+		for_each_string_list_item(item, &existing->cruft_packs)
+			fprintf(in, "-%s.pack\n", item->string);
+	}
+	for_each_string_list_item(item, &existing->kept_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	fclose(in);
+
+	return finish_pack_objects_cmd(existing->repo->hash_algo, opts, &cmd,
+				       names);
+}
diff --git a/repack.h b/repack.h
index a7ddbe784b..15886c3488 100644
--- a/repack.h
+++ b/repack.h
@@ -137,4 +137,10 @@ int write_filtered_pack(struct write_pack_opts *opts,
 			struct existing_packs *existing,
 			struct string_list *names);
 
+int write_cruft_pack(struct write_pack_opts *opts,
+		     const char *cruft_expiration,
+		     unsigned long combine_cruft_below_size,
+		     struct string_list *names,
+		     struct existing_packs *existing);
+
 #endif /* REPACK_H */