4 files changed, 101 insertions, 4 deletions

diff --git a/fetch-object.c b/fetch-object.c
index 258fcfac75..853624f811 100644
--- a/fetch-object.c
+++ b/fetch-object.c
@@ -5,11 +5,10 @@
 #include "transport.h"
 #include "fetch-object.h"
 
-void fetch_object(const char *remote_name, const unsigned char *sha1)
+static void fetch_refs(const char *remote_name, struct ref *ref)
 {
 	struct remote *remote;
 	struct transport *transport;
-	struct ref *ref;
 	int original_fetch_if_missing = fetch_if_missing;
 
 	fetch_if_missing = 0;
@@ -18,10 +17,29 @@ void fetch_object(const char *remote_name, const unsigned char *sha1)
 		die(_("Remote with no URL"));
 	transport = transport_get(remote, remote->url[0]);
 
-	ref = alloc_ref(sha1_to_hex(sha1));
-	hashcpy(ref->old_oid.hash, sha1);
 	transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
 	transport_set_option(transport, TRANS_OPT_NO_DEPENDENTS, "1");
 	transport_fetch_refs(transport, ref);
 	fetch_if_missing = original_fetch_if_missing;
 }
+
+void fetch_object(const char *remote_name, const unsigned char *sha1)
+{
+	struct ref *ref = alloc_ref(sha1_to_hex(sha1));
+	hashcpy(ref->old_oid.hash, sha1);
+	fetch_refs(remote_name, ref);
+}
+
+void fetch_objects(const char *remote_name, const struct oid_array *to_fetch)
+{
+	struct ref *ref = NULL;
+	int i;
+
+	for (i = 0; i < to_fetch->nr; i++) {
+		struct ref *new_ref = alloc_ref(oid_to_hex(&to_fetch->oid[i]));
+		oidcpy(&new_ref->old_oid, &to_fetch->oid[i]);
+		new_ref->next = ref;
+		ref = new_ref;
+	}
+	fetch_refs(remote_name, ref);
+}
diff --git a/fetch-object.h b/fetch-object.h
index f371300c88..4b269d07ed 100644
--- a/fetch-object.h
+++ b/fetch-object.h
@@ -1,6 +1,11 @@
 #ifndef FETCH_OBJECT_H
 #define FETCH_OBJECT_H
 
+#include "sha1-array.h"
+
 extern void fetch_object(const char *remote_name, const unsigned char *sha1);
 
+extern void fetch_objects(const char *remote_name,
+			  const struct oid_array *to_fetch);
+
 #endif
diff --git a/t/t5601-clone.sh b/t/t5601-clone.sh
index 6d37c6d781..13610b70f5 100755
--- a/t/t5601-clone.sh
+++ b/t/t5601-clone.sh
@@ -611,6 +611,58 @@ test_expect_success 'partial clone: warn if server does not support object filte
 	test_i18ngrep "filtering not recognized by server" err
 '
 
+test_expect_success 'batch missing blob request during checkout' '
+	rm -rf server client &&
+
+	test_create_repo server &&
+	echo a >server/a &&
+	echo b >server/b &&
+	git -C server add a b &&
+
+	git -C server commit -m x &&
+	echo aa >server/a &&
+	echo bb >server/b &&
+	git -C server add a b &&
+	git -C server commit -m x &&
+
+	test_config -C server uploadpack.allowfilter 1 &&
+	test_config -C server uploadpack.allowanysha1inwant 1 &&
+
+	git clone --filter=blob:limit=0 "file://$(pwd)/server" client &&
+
+	# Ensure that there is only one negotiation by checking that there is
+	# only "done" line sent. ("done" marks the end of negotiation.)
+	GIT_TRACE_PACKET="$(pwd)/trace" git -C client checkout HEAD^ &&
+	grep "git> done" trace >done_lines &&
+	test_line_count = 1 done_lines
+'
+
+test_expect_success 'batch missing blob request does not inadvertently try to fetch gitlinks' '
+	rm -rf server client &&
+
+	test_create_repo repo_for_submodule &&
+	test_commit -C repo_for_submodule x &&
+
+	test_create_repo server &&
+	echo a >server/a &&
+	echo b >server/b &&
+	git -C server add a b &&
+	git -C server commit -m x &&
+
+	echo aa >server/a &&
+	echo bb >server/b &&
+	# Also add a gitlink pointing to an arbitrary repository
+	git -C server submodule add "$(pwd)/repo_for_submodule" c &&
+	git -C server add a b c &&
+	git -C server commit -m x &&
+
+	test_config -C server uploadpack.allowfilter 1 &&
+	test_config -C server uploadpack.allowanysha1inwant 1 &&
+
+	# Make sure that it succeeds
+	git clone --filter=blob:limit=0 "file://$(pwd)/server" client
+'
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd
 
diff --git a/unpack-trees.c b/unpack-trees.c
index 71b70ccb12..73a1cdb43e 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -14,6 +14,7 @@
 #include "dir.h"
 #include "submodule.h"
 #include "submodule-config.h"
+#include "fetch-object.h"
 
 /*
  * Error messages expected by scripts out of plumbing commands such as
@@ -369,6 +370,27 @@ static int check_updates(struct unpack_trees_options *o)
 		load_gitmodules_file(index, &state);
 
 	enable_delayed_checkout(&state);
+	if (repository_format_partial_clone && o->update && !o->dry_run) {
+		/*
+		 * Prefetch the objects that are to be checked out in the loop
+		 * below.
+		 */
+		struct oid_array to_fetch = OID_ARRAY_INIT;
+		int fetch_if_missing_store = fetch_if_missing;
+		fetch_if_missing = 0;
+		for (i = 0; i < index->cache_nr; i++) {
+			struct cache_entry *ce = index->cache[i];
+			if ((ce->ce_flags & CE_UPDATE) &&
+			    !S_ISGITLINK(ce->ce_mode)) {
+				if (!has_object_file(&ce->oid))
+					oid_array_append(&to_fetch, &ce->oid);
+			}
+		}
+		if (to_fetch.nr)
+			fetch_objects(repository_format_partial_clone,
+				      &to_fetch);
+		fetch_if_missing = fetch_if_missing_store;
+	}
 	for (i = 0; i < index->cache_nr; i++) {
 		struct cache_entry *ce = index->cache[i];