diff --git a/builtin/add.c b/builtin/add.c
index c859f66519..60ffbede2b 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -581,7 +581,7 @@ int cmd_add(int argc,
 		string_list_clear(&only_match_skip_worktree, 0);
 	}
 
-	transaction = odb_transaction_begin(repo->objects);
+	odb_transaction_begin_or_die(repo->objects, &transaction, 0);
 
 	ps_matched = xcalloc(pathspec.nr, 1);
 	if (add_renormalize)
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index faf0f120ac..7190d7f430 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -37,7 +37,6 @@
 #include "sigchain.h"
 #include "string-list.h"
 #include "strvec.h"
-#include "tmp-objdir.h"
 #include "trace.h"
 #include "trace2.h"
 #include "version.h"
@@ -112,8 +111,6 @@ static enum {
 } use_keepalive;
 static int keepalive_in_sec = 5;
 
-static struct tmp_objdir *tmp_objdir;
-
 static struct proc_receive_ref {
 	unsigned int want_add:1,
 		     want_delete:1,
@@ -926,6 +923,7 @@ static void receive_hook_feed_state_free(void *data)
 static int run_receive_hook(struct command *commands,
 			    const char *hook_name,
 			    int skip_broken,
+			    struct odb_transaction *transaction,
 			    const struct string_list *push_options)
 {
 	struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
@@ -959,8 +957,8 @@ static int run_receive_hook(struct command *commands,
 		strvec_push(&opt.env, "GIT_PUSH_OPTION_COUNT");
 	}
 
-	if (tmp_objdir)
-		strvec_pushv(&opt.env, tmp_objdir_env(tmp_objdir));
+	if (transaction)
+		odb_transaction_env(transaction, &opt.env);
 
 	prepare_push_cert_sha1(&opt);
 
@@ -1363,7 +1361,6 @@ static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
 		    !delayed_reachability_test(si, i))
 			oid_array_append(&extra, &si->shallow->oid[i]);
 
-	opt.env = tmp_objdir_env(tmp_objdir);
 	setup_alternate_shallow(&shallow_lock, &opt.shallow_file, &extra);
 	if (check_connected(command_singleton_iterator, cmd, &opt)) {
 		rollback_shallow_file(the_repository, &shallow_lock);
@@ -1790,24 +1787,30 @@ static const struct object_id *command_singleton_iterator(void *cb_data)
 }
 
 static void set_connectivity_errors(struct command *commands,
-				    struct shallow_info *si)
+				    struct shallow_info *si,
+				    struct odb_transaction *transaction)
 {
 	struct command *cmd;
 
 	for (cmd = commands; cmd; cmd = cmd->next) {
 		struct command *singleton = cmd;
 		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+		struct strvec env = STRVEC_INIT;
 
 		if (shallow_update && si->shallow_ref[cmd->index])
 			/* to be checked in update_shallow_ref() */
 			continue;
 
-		opt.env = tmp_objdir_env(tmp_objdir);
+		odb_transaction_env(transaction, &env);
+		opt.env = env.v;
+
 		if (!check_connected(command_singleton_iterator, &singleton,
 				     &opt))
 			continue;
 
 		cmd->error_string = "missing necessary objects";
+
+		strvec_clear(&env);
 	}
 }
 
@@ -2028,6 +2031,7 @@ cleanup:
 static void execute_commands(struct command *commands,
 			     const char *unpacker_error,
 			     struct shallow_info *si,
+			     struct odb_transaction *transaction,
 			     const struct string_list *push_options)
 {
 	struct check_connected_options opt = CHECK_CONNECTED_INIT;
@@ -2044,6 +2048,8 @@ static void execute_commands(struct command *commands,
 	}
 
 	if (!skip_connectivity_check) {
+		struct strvec env = STRVEC_INIT;
+
 		if (use_sideband) {
 			memset(&muxer, 0, sizeof(muxer));
 			muxer.proc = copy_to_sideband;
@@ -2057,14 +2063,17 @@ static void execute_commands(struct command *commands,
 		data.si = si;
 		opt.err_fd = err_fd;
 		opt.progress = err_fd && !quiet;
-		opt.env = tmp_objdir_env(tmp_objdir);
+		odb_transaction_env(transaction, &env);
+		opt.env = env.v;
 		opt.exclude_hidden_refs_section = "receive";
 
 		if (check_connected(iterate_receive_command_list, &data, &opt))
-			set_connectivity_errors(commands, si);
+			set_connectivity_errors(commands, si, transaction);
 
 		if (use_sideband)
 			finish_async(&muxer);
+
+		strvec_clear(&env);
 	}
 
 	reject_updates_to_hidden(commands);
@@ -2085,7 +2094,7 @@ static void execute_commands(struct command *commands,
 		}
 	}
 
-	if (run_receive_hook(commands, "pre-receive", 0, push_options)) {
+	if (run_receive_hook(commands, "pre-receive", 0, transaction, push_options)) {
 		for (cmd = commands; cmd; cmd = cmd->next) {
 			if (!cmd->error_string)
 				cmd->error_string = "pre-receive hook declined";
@@ -2106,14 +2115,13 @@ static void execute_commands(struct command *commands,
 	 * Now we'll start writing out refs, which means the objects need
 	 * to be in their final positions so that other processes can see them.
 	 */
-	if (tmp_objdir_migrate(tmp_objdir) < 0) {
+	if (odb_transaction_commit(transaction)) {
 		for (cmd = commands; cmd; cmd = cmd->next) {
 			if (!cmd->error_string)
 				cmd->error_string = "unable to migrate objects to permanent storage";
 		}
 		return;
 	}
-	tmp_objdir = NULL;
 
 	check_aliased_updates(commands);
 
@@ -2326,7 +2334,8 @@ static void push_header_arg(struct strvec *args, struct pack_header *hdr)
 		     ntohl(hdr->hdr_version), ntohl(hdr->hdr_entries));
 }
 
-static const char *unpack(int err_fd, struct shallow_info *si)
+static const char *unpack(int err_fd, struct shallow_info *si,
+			  struct odb_transaction *transaction)
 {
 	struct pack_header hdr;
 	const char *hdr_err;
@@ -2351,20 +2360,7 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 		strvec_push(&child.args, alt_shallow_file);
 	}
 
-	tmp_objdir = tmp_objdir_create(the_repository, "incoming");
-	if (!tmp_objdir) {
-		if (err_fd > 0)
-			close(err_fd);
-		return "unable to create temporary object directory";
-	}
-	strvec_pushv(&child.env, tmp_objdir_env(tmp_objdir));
-
-	/*
-	 * Normally we just pass the tmp_objdir environment to the child
-	 * processes that do the heavy lifting, but we may need to see these
-	 * objects ourselves to set up shallow information.
-	 */
-	tmp_objdir_add_as_alternate(tmp_objdir);
+	odb_transaction_env(transaction, &child.env);
 
 	if (ntohl(hdr.hdr_entries) < unpack_limit) {
 		strvec_push(&child.args, "unpack-objects");
@@ -2431,13 +2427,14 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 	return NULL;
 }
 
-static const char *unpack_with_sideband(struct shallow_info *si)
+static const char *unpack_with_sideband(struct shallow_info *si,
+					struct odb_transaction *transaction)
 {
 	struct async muxer;
 	const char *ret;
 
 	if (!use_sideband)
-		return unpack(0, si);
+		return unpack(0, si, transaction);
 
 	use_keepalive = KEEPALIVE_AFTER_NUL;
 	memset(&muxer, 0, sizeof(muxer));
@@ -2446,7 +2443,7 @@ static const char *unpack_with_sideband(struct shallow_info *si)
 	if (start_async(&muxer))
 		return NULL;
 
-	ret = unpack(muxer.in, si);
+	ret = unpack(muxer.in, si, transaction);
 
 	finish_async(&muxer);
 	return ret;
@@ -2623,6 +2620,7 @@ int cmd_receive_pack(int argc,
 	struct oid_array ref = OID_ARRAY_INIT;
 	struct shallow_info si;
 	struct packet_reader reader;
+	struct odb_transaction *transaction = NULL;
 
 	struct option options[] = {
 		OPT__QUIET(&quiet, N_("quiet")),
@@ -2707,11 +2705,14 @@ int cmd_receive_pack(int argc,
 		if (!si.nr_ours && !si.nr_theirs)
 			shallow_update = 0;
 		if (!delete_only(commands)) {
-			unpack_status = unpack_with_sideband(&si);
+			if (odb_transaction_begin(the_repository->objects, &transaction, ODB_TRANSACTION_RECEIVE))
+				unpack_status = "unable to start object transaction";
+			else
+				unpack_status = unpack_with_sideband(&si, transaction);
 			update_shallow_info(commands, &si, &ref);
 		}
 		use_keepalive = KEEPALIVE_ALWAYS;
-		execute_commands(commands, unpack_status, &si,
+		execute_commands(commands, unpack_status, &si, transaction,
 				 &push_options);
 		delete_tempfile(&pack_lockfile);
 		sigchain_push(SIGPIPE, SIG_IGN);
@@ -2720,7 +2721,7 @@ int cmd_receive_pack(int argc,
 		else if (report_status)
 			report(commands, unpack_status);
 		sigchain_pop(SIGPIPE);
-		run_receive_hook(commands, "post-receive", 1,
+		run_receive_hook(commands, "post-receive", 1, NULL,
 				 &push_options);
 		run_update_post_hook(commands);
 		free_commands(commands);
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 93a9caa582..4263edfbec 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -598,7 +598,7 @@ static void unpack_all(void)
 		progress = start_progress(the_repository,
 					  _("Unpacking objects"), nr_objects);
 	CALLOC_ARRAY(obj_list, nr_objects);
-	transaction = odb_transaction_begin(the_repository->objects);
+	odb_transaction_begin_or_die(the_repository->objects, &transaction, 0);
 	for (i = 0; i < nr_objects; i++) {
 		unpack_one(i);
 		display_progress(progress, i + 1);
diff --git a/builtin/update-index.c b/builtin/update-index.c
index 5d80d4827d..4c4b39a157 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -1124,7 +1124,7 @@ int cmd_update_index(int argc,
 	 * Allow the object layer to optimize adding multiple objects in
 	 * a batch.
 	 */
-	transaction = odb_transaction_begin(the_repository->objects);
+	odb_transaction_begin_or_die(the_repository->objects, &transaction, 0);
 	while (ctx.argc) {
 		if (parseopt_state != PARSE_OPT_DONE)
 			parseopt_state = parse_options_step(&ctx, options,
diff --git a/cache-tree.c b/cache-tree.c
index 9204eb3ac7..d92f513286 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -516,6 +516,7 @@ static int update_one(struct cache_tree *it,
 
 int cache_tree_update(struct index_state *istate, int flags)
 {
+	int inflight = !!the_repository->objects->transaction;
 	struct odb_transaction *transaction;
 	int skip, i;
 
@@ -532,10 +533,12 @@ int cache_tree_update(struct index_state *istate, int flags)
 
 	trace_performance_enter();
 	trace2_region_enter("cache_tree", "update", istate->repo);
-	transaction = odb_transaction_begin(the_repository->objects);
+	if (!inflight)
+		odb_transaction_begin_or_die(the_repository->objects, &transaction, 0);
 	i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,
 		       "", 0, &skip, flags);
-	odb_transaction_commit(transaction);
+	if (!inflight)
+		odb_transaction_commit(transaction);
 	trace2_region_leave("cache_tree", "update", istate->repo);
 	trace_performance_leave("cache_tree_update");
 	if (i < 0)
diff --git a/object-file.c b/object-file.c
index 2d84f08713..7ff2b730ac 100644
--- a/object-file.c
+++ b/object-file.c
@@ -27,6 +27,7 @@
 #include "path.h"
 #include "read-cache-ll.h"
 #include "setup.h"
+#include "strvec.h"
 #include "tempfile.h"
 #include "tmp-objdir.h"
 
@@ -494,9 +495,10 @@ struct odb_transaction_files {
 
 	struct tmp_objdir *objdir;
 	struct transaction_packfile packfile;
+	const char *prefix;
 };
 
-static void prepare_loose_object_transaction(struct odb_transaction *base)
+static int odb_transaction_files_prepare(struct odb_transaction *base)
 {
 	struct odb_transaction_files *transaction =
 		container_of_or_null(base, struct odb_transaction_files, base);
@@ -508,19 +510,28 @@ static void prepare_loose_object_transaction(struct odb_transaction *base)
 	 * added at the time they call odb_transaction_files_begin.
 	 */
 	if (!transaction || transaction->objdir)
-		return;
+		return 0;
 
-	transaction->objdir = tmp_objdir_create(base->source->odb->repo, "bulk-fsync");
-	if (transaction->objdir)
-		tmp_objdir_replace_primary_odb(transaction->objdir, 0);
+	transaction->objdir = tmp_objdir_create(base->source->odb->repo, transaction->prefix);
+	if (!transaction->objdir)
+		return error(_("unable to create temporary object directory"));
+
+	tmp_objdir_replace_primary_odb(transaction->objdir, 0);
+
+	return 0;
 }
 
-static void fsync_loose_object_transaction(struct odb_transaction *base,
-					   int fd, const char *filename)
+static void odb_transaction_files_fsync(struct odb_transaction *base,
+					int fd, const char *filename)
 {
 	struct odb_transaction_files *transaction =
 		container_of_or_null(base, struct odb_transaction_files, base);
 
+	if (!transaction || !transaction->objdir) {
+		fsync_or_die(fd, filename);
+		return;
+	}
+
 	/*
 	 * If we have an active ODB transaction, we issue a call that
 	 * cleans the filesystem page cache but avoids a hardware flush
@@ -528,49 +539,13 @@ static void fsync_loose_object_transaction(struct odb_transaction *base,
 	 * before renaming the objects to their final names as part of
 	 * flush_batch_fsync.
 	 */
-	if (!transaction || !transaction->objdir ||
-	    git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
+	if (git_fsync(fd, FSYNC_WRITEOUT_ONLY) < 0) {
 		if (errno == ENOSYS)
 			warning(_("core.fsyncMethod = batch is unsupported on this platform"));
 		fsync_or_die(fd, filename);
 	}
 }
 
-/*
- * Cleanup after batch-mode fsync_object_files.
- */
-static void flush_loose_object_transaction(struct odb_transaction_files *transaction)
-{
-	struct strbuf temp_path = STRBUF_INIT;
-	struct tempfile *temp;
-
-	if (!transaction->objdir)
-		return;
-
-	/*
-	 * Issue a full hardware flush against a temporary file to ensure
-	 * that all objects are durable before any renames occur. The code in
-	 * fsync_loose_object_transaction has already issued a writeout
-	 * request, but it has not flushed any writeback cache in the storage
-	 * hardware or any filesystem logs. This fsync call acts as a barrier
-	 * to ensure that the data in each new object file is durable before
-	 * the final name is visible.
-	 */
-	strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX",
-		    repo_get_object_directory(transaction->base.source->odb->repo));
-	temp = xmks_tempfile(temp_path.buf);
-	fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
-	delete_tempfile(&temp);
-	strbuf_release(&temp_path);
-
-	/*
-	 * Make the object files visible in the primary ODB after their data is
-	 * fully durable.
-	 */
-	tmp_objdir_migrate(transaction->objdir);
-	transaction->objdir = NULL;
-}
-
 /* Finalize a file on disk, and close it. */
 static void close_loose_object(struct odb_source_loose *loose,
 			       int fd, const char *filename)
@@ -579,7 +554,7 @@ static void close_loose_object(struct odb_source_loose *loose,
 		goto out;
 
 	if (batch_fsync_enabled(FSYNC_COMPONENT_LOOSE_OBJECT))
-		fsync_loose_object_transaction(loose->base.odb->transaction, fd, filename);
+		odb_transaction_files_fsync(loose->base.odb->transaction, fd, filename);
 	else if (fsync_object_files > 0)
 		fsync_or_die(fd, filename);
 	else
@@ -758,7 +733,7 @@ int write_loose_object(struct odb_source_loose *loose,
 	static struct strbuf filename = STRBUF_INIT;
 
 	if (batch_fsync_enabled(FSYNC_COMPONENT_LOOSE_OBJECT))
-		prepare_loose_object_transaction(loose->base.odb->transaction);
+		odb_transaction_files_prepare(loose->base.odb->transaction);
 
 	odb_loose_path(loose, &filename, oid);
 
@@ -822,7 +797,7 @@ int odb_source_loose_write_stream(struct odb_source_loose *loose,
 	int hdrlen;
 
 	if (batch_fsync_enabled(FSYNC_COMPONENT_LOOSE_OBJECT))
-		prepare_loose_object_transaction(loose->base.odb->transaction);
+		odb_transaction_files_prepare(loose->base.odb->transaction);
 
 	/* Since oid is not determined, save tmp file to odb path. */
 	strbuf_addf(&filename, "%s/", loose->base.path);
@@ -1380,13 +1355,17 @@ int index_fd(struct index_state *istate, struct object_id *oid,
 
 		if (flags & INDEX_WRITE_OBJECT) {
 			struct object_database *odb = the_repository->objects;
-			struct odb_transaction *transaction = odb_transaction_begin(odb);
+			struct odb_transaction *transaction = odb->transaction;
+			int inflight = !!transaction;
 
-			ret = odb_transaction_write_object_stream(odb->transaction,
+			if (!inflight)
+				odb_transaction_begin_or_die(odb, &transaction, 0);
+			ret = odb_transaction_write_object_stream(transaction,
 								  &stream,
 								  xsize_t(st->st_size),
 								  oid);
-			odb_transaction_commit(transaction);
+			if (!inflight)
+				odb_transaction_commit(transaction);
 		} else {
 			ret = hash_blob_stream(&stream,
 					       the_repository->hash_algo, oid,
@@ -1671,27 +1650,93 @@ out:
 	return ret;
 }
 
-static void odb_transaction_files_commit(struct odb_transaction *base)
+static int odb_transaction_files_commit(struct odb_transaction *base)
 {
 	struct odb_transaction_files *transaction =
 		container_of(base, struct odb_transaction_files, base);
 
-	flush_loose_object_transaction(transaction);
+	if (transaction->objdir) {
+		struct strbuf temp_path = STRBUF_INIT;
+		struct tempfile *temp;
+
+		/*
+		 * Issue a full hardware flush against a temporary file to ensure
+		 * that all objects are durable before any renames occur. The code in
+		 * odb_transaction_files_fsync has already issued a writeout
+		 * request, but it has not flushed any writeback cache in the storage
+		 * hardware or any filesystem logs. This fsync call acts as a barrier
+		 * to ensure that the data in each new object file is durable before
+		 * the final name is visible.
+		 */
+		strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX",
+			    repo_get_object_directory(transaction->base.source->odb->repo));
+		temp = xmks_tempfile(temp_path.buf);
+		fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
+		delete_tempfile(&temp);
+		strbuf_release(&temp_path);
+
+		/*
+		 * Make the object files visible in the primary ODB after their data is
+		 * fully durable.
+		 */
+		if (tmp_objdir_migrate(transaction->objdir))
+			return error(_("unable to migrate temporary objects"));
+
+		transaction->objdir = NULL;
+	}
+
 	flush_packfile_transaction(transaction);
+
+	return 0;
 }
 
-struct odb_transaction *odb_transaction_files_begin(struct odb_source *source)
+static int odb_transaction_files_env(struct odb_transaction *base,
+				     struct strvec *env)
+{
+	struct odb_transaction_files *transaction =
+		container_of(base, struct odb_transaction_files, base);
+	int ret;
+
+	ret = odb_transaction_files_prepare(&transaction->base);
+	if (!ret)
+		strvec_pushv(env, tmp_objdir_env(transaction->objdir));
+
+	return ret;
+}
+
+int odb_transaction_files_begin(struct odb_source *source,
+				struct odb_transaction **out,
+				enum odb_transaction_flags flags)
 {
 	struct odb_transaction_files *transaction;
-	struct object_database *odb = source->odb;
-
-	if (odb->transaction)
-		return NULL;
 
 	transaction = xcalloc(1, sizeof(*transaction));
 	transaction->base.source = source;
 	transaction->base.commit = odb_transaction_files_commit;
 	transaction->base.write_object_stream = odb_transaction_files_write_object_stream;
+	transaction->base.env = odb_transaction_files_env;
 
-	return &transaction->base;
+	transaction->prefix = "bulk-fsync";
+	if (flags & ODB_TRANSACTION_RECEIVE) {
+		/*
+		 * ODB transactions for git-receive-pack(1) eagerly create a
+		 * temporary directory and use a different temporary directory
+		 * prefix.
+		 *
+		 * NEEDSWORK: This transaction flag is only used by the "files"
+		 * backend to special case temporary directory set up and
+		 * handling. Ideally transaction users should not have to care
+		 * though. To avoid this, we could eagerly create the temporary
+		 * directory and use the same prefix name for all transactions.
+		 */
+		transaction->prefix = "incoming";
+		if (odb_transaction_files_prepare(&transaction->base)) {
+			free(transaction);
+			return -1;
+		}
+	}
+
+	*out = &transaction->base;
+
+	return 0;
 }
diff --git a/object-file.h b/object-file.h
index 4c87cd160b..d04ffa6493 100644
--- a/object-file.h
+++ b/object-file.h
@@ -5,6 +5,7 @@
 #include "object.h"
 #include "odb.h"
 #include "odb/source-loose.h"
+#include "odb/transaction.h"
 
 /* The maximum size for an object header. */
 #define MAX_HEADER_LEN 32
@@ -194,9 +195,10 @@ struct odb_transaction;
 /*
  * Tell the object database to optimize for adding
  * multiple objects. odb_transaction_files_commit must be called
- * to make new objects visible. If a transaction is already
- * pending, NULL is returned.
+ * to make new objects visible.
  */
-struct odb_transaction *odb_transaction_files_begin(struct odb_source *source);
+int odb_transaction_files_begin(struct odb_source *source,
+				struct odb_transaction **out,
+				enum odb_transaction_flags flags);
 
 #endif /* OBJECT_FILE_H */
diff --git a/odb/source-files.c b/odb/source-files.c
index 6c8e935c75..4138758511 100644
--- a/odb/source-files.c
+++ b/odb/source-files.c
@@ -181,13 +181,10 @@ static int odb_source_files_write_object_stream(struct odb_source *source,
 }
 
 static int odb_source_files_begin_transaction(struct odb_source *source,
-					      struct odb_transaction **out)
+					      struct odb_transaction **out,
+					      enum odb_transaction_flags flags)
 {
-	struct odb_transaction *tx = odb_transaction_files_begin(source);
-	if (!tx)
-		return -1;
-	*out = tx;
-	return 0;
+	return odb_transaction_files_begin(source, out, flags);
 }
 
 static int odb_source_files_read_alternates(struct odb_source *source,
diff --git a/odb/source-inmemory.c b/odb/source-inmemory.c
index f41a602e64..e47bfd8fcc 100644
--- a/odb/source-inmemory.c
+++ b/odb/source-inmemory.c
@@ -305,7 +305,8 @@ static int odb_source_inmemory_freshen_object(struct odb_source *source,
 }
 
 static int odb_source_inmemory_begin_transaction(struct odb_source *source UNUSED,
-						 struct odb_transaction **out UNUSED)
+						 struct odb_transaction **out UNUSED,
+						 enum odb_transaction_flags flags UNUSED)
 {
 	return error("in-memory source does not support transactions");
 }
diff --git a/odb/source-loose.c b/odb/source-loose.c
index 091e8e00a7..3f7d04a56e 100644
--- a/odb/source-loose.c
+++ b/odb/source-loose.c
@@ -638,7 +638,8 @@ static int odb_source_loose_write_object_stream(struct odb_source *source,
 }
 
 static int odb_source_loose_begin_transaction(struct odb_source *source UNUSED,
-					      struct odb_transaction **out UNUSED)
+					      struct odb_transaction **out UNUSED,
+					      enum odb_transaction_flags flags UNUSED)
 {
 	/* TODO: this is a known omission that we'll want to address eventually. */
 	return error("loose source does not support transactions");
diff --git a/odb/source-packed.c b/odb/source-packed.c
index 647f23cdb9..8d9ce197cc 100644
--- a/odb/source-packed.c
+++ b/odb/source-packed.c
@@ -545,7 +545,8 @@ static int odb_source_packed_write_object_stream(struct odb_source *source UNUSE
 }
 
 static int odb_source_packed_begin_transaction(struct odb_source *source UNUSED,
-					       struct odb_transaction **out UNUSED)
+					       struct odb_transaction **out UNUSED,
+					       enum odb_transaction_flags flags UNUSED)
 {
 	return error("packed backend cannot begin transactions");
 }
diff --git a/odb/source.h b/odb/source.h
index efeff7ed12..cd63dba91f 100644
--- a/odb/source.h
+++ b/odb/source.h
@@ -3,6 +3,7 @@
 
 #include "object.h"
 #include "odb.h"
+#include "odb/transaction.h"
 
 enum odb_source_type {
 	/*
@@ -232,7 +233,8 @@ struct odb_source {
 	 * negative error code otherwise.
 	 */
 	int (*begin_transaction)(struct odb_source *source,
-				 struct odb_transaction **out);
+				 struct odb_transaction **out,
+				 enum odb_transaction_flags flags);
 
 	/*
 	 * This callback is expected to read the list of alternate object
@@ -472,9 +474,10 @@ static inline int odb_source_write_alternate(struct odb_source *source,
  * Returns 0 on success, a negative error code otherwise.
  */
 static inline int odb_source_begin_transaction(struct odb_source *source,
-					       struct odb_transaction **out)
+					       struct odb_transaction **out,
+					       enum odb_transaction_flags flags)
 {
-	return source->begin_transaction(source, out);
+	return source->begin_transaction(source, out, flags);
 }
 
 #endif
diff --git a/odb/transaction.c b/odb/transaction.c
index b16e07aebf..dab7da6a9a 100644
--- a/odb/transaction.c
+++ b/odb/transaction.c
@@ -1,30 +1,41 @@
 #include "git-compat-util.h"
+#include "gettext.h"
 #include "odb/source.h"
 #include "odb/transaction.h"
 
-struct odb_transaction *odb_transaction_begin(struct object_database *odb)
+int odb_transaction_begin(struct object_database *odb,
+			  struct odb_transaction **out,
+			  enum odb_transaction_flags flags)
 {
+	int ret;
+
 	if (odb->transaction)
-		return NULL;
+		return error(_("object database transaction already pending"));
 
-	odb_source_begin_transaction(odb->sources, &odb->transaction);
+	ret = odb_source_begin_transaction(odb->sources, out, flags);
+	if (!ret)
+		odb->transaction = *out;
 
-	return odb->transaction;
+	return ret;
 }
 
-void odb_transaction_commit(struct odb_transaction *transaction)
+int odb_transaction_commit(struct odb_transaction *transaction)
 {
+	int ret;
+
 	if (!transaction)
-		return;
+		return 0;
 
 	/*
 	 * Ensure the transaction ending matches the pending transaction.
 	 */
 	ASSERT(transaction == transaction->source->odb->transaction);
 
-	transaction->commit(transaction);
+	ret = transaction->commit(transaction);
 	transaction->source->odb->transaction = NULL;
 	free(transaction);
+
+	return ret;
 }
 
 int odb_transaction_write_object_stream(struct odb_transaction *transaction,
@@ -33,3 +44,11 @@ int odb_transaction_write_object_stream(struct odb_transaction *transaction,
 {
 	return transaction->write_object_stream(transaction, stream, len, oid);
 }
+
+int odb_transaction_env(struct odb_transaction *transaction, struct strvec *env)
+{
+	if (!transaction)
+		return 0;
+
+	return transaction->env(transaction, env);
+}
diff --git a/odb/transaction.h b/odb/transaction.h
index 854fda06f5..4cb2eafcbf 100644
--- a/odb/transaction.h
+++ b/odb/transaction.h
@@ -1,8 +1,8 @@
 #ifndef ODB_TRANSACTION_H
 #define ODB_TRANSACTION_H
 
+#include "gettext.h"
 #include "odb.h"
-#include "odb/source.h"
 
 /*
  * A transaction may be started for an object database prior to writing new
@@ -16,8 +16,11 @@ struct odb_transaction {
 	/* The ODB source the transaction is opened against. */
 	struct odb_source *source;
 
-	/* The ODB source specific callback invoked to commit a transaction. */
-	void (*commit)(struct odb_transaction *transaction);
+	/*
+	 * The ODB source specific callback invoked to commit a transaction.
+	 * Returns 0 on success, a negative error code otherwise.
+	 */
+	int (*commit)(struct odb_transaction *transaction);
 
 	/*
 	 * This callback is expected to write the given object stream into
@@ -30,20 +33,47 @@ struct odb_transaction {
 	int (*write_object_stream)(struct odb_transaction *transaction,
 				   struct odb_write_stream *stream, size_t len,
 				   struct object_id *oid);
+
+	/*
+	 * This callback is expected to populate the provided strvec with the
+	 * environment variables that a child process should inherit so that its
+	 * object writes participate in the transaction. Returns 0 on success, a
+	 * negative error code otherwise.
+	 */
+	int (*env)(struct odb_transaction *transaction, struct strvec *env);
+};
+
+/* Flags used to configure an ODB transaction. */
+enum odb_transaction_flags {
+	/* Configures the transaction for use with git-receive-pack(1). */
+	ODB_TRANSACTION_RECEIVE = (1 << 0),
 };
 
 /*
- * Starts an ODB transaction. Subsequent objects are written to the transaction
- * and not committed until odb_transaction_commit() is invoked on the
- * transaction. If the ODB already has a pending transaction, NULL is returned.
+ * Starts an ODB transaction and returns it via `out`. Subsequent objects are
+ * written to the transaction and not committed until odb_transaction_commit()
+ * is invoked on the transaction. Returns 0 on success and a negative value on
+ * error. Note that it is considered an error to start a new transaction if the
+ * ODB already has an inflight transaction pending.
  */
-struct odb_transaction *odb_transaction_begin(struct object_database *odb);
+int odb_transaction_begin(struct object_database *odb,
+			  struct odb_transaction **out,
+			  enum odb_transaction_flags flags);
+
+static inline void odb_transaction_begin_or_die(struct object_database *odb,
+						struct odb_transaction **out,
+						enum odb_transaction_flags flags)
+{
+	if (odb_transaction_begin(odb, out, flags))
+		die(_("failed to start ODB transaction"));
+}
 
 /*
- * Commits an ODB transaction making the written objects visible. If the
- * specified transaction is NULL, the function is a no-op.
+ * Commits an ODB transaction making the written objects visible. Returns 0 on
+ * success, a negative error code otherwise. Note that, if the specified
+ * transaction is NULL, the function is a no-op and no error is returned.
  */
-void odb_transaction_commit(struct odb_transaction *transaction);
+int odb_transaction_commit(struct odb_transaction *transaction);
 
 /*
  * Writes the object in the provided stream into the transaction. The resulting
@@ -54,4 +84,13 @@ int odb_transaction_write_object_stream(struct odb_transaction *transaction,
 					struct odb_write_stream *stream,
 					size_t len, struct object_id *oid);
 
+/*
+ * Populates the provided strvec with the environment variables that a child
+ * process should inherit so that its object writes participate in the
+ * transaction, suitable for using via child_process.env. Returns 0 on success,
+ * a negative error code otherwise. Note that, if the specified transaction is
+ * NULL, the function is a no-op and no error is returned.
+ */
+int odb_transaction_env(struct odb_transaction *transaction, struct strvec *env);
+
 #endif
diff --git a/read-cache.c b/read-cache.c
index 797fdfc07d..38b55323dd 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -4015,6 +4015,7 @@ int add_files_to_cache(struct repository *repo, const char *prefix,
 		       const struct pathspec *pathspec, char *ps_matched,
 		       int include_sparse, int flags, int ignored_too )
 {
+	int inflight = !!repo->objects->transaction;
 	struct odb_transaction *transaction;
 	struct update_callback_data data;
 	struct rev_info rev;
@@ -4045,9 +4046,11 @@ int add_files_to_cache(struct repository *repo, const char *prefix,
 	 * This function is invoked from commands other than 'add', which
 	 * may not have their own transaction active.
 	 */
-	transaction = odb_transaction_begin(repo->objects);
+	if (!inflight)
+		odb_transaction_begin_or_die(repo->objects, &transaction, 0);
 	run_diff_files(&rev, DIFF_RACY_IS_MODIFIED);
-	odb_transaction_commit(transaction);
+	if (!inflight)
+		odb_transaction_commit(transaction);
 
 	release_revisions(&rev);
 	return !!data.add_errors;