object-file: flush transaction packfile before migrating objects

A "files" ODB transaction creates a temporary directory to stage newly
written objects in when configured to batch fsync loose objects. Once
the temporary directory is created, it is configured as the primary ODB
and all object are written to it accordingly. This also includes
packfiles containing blobs that exceed `core.bigFileThreshold` written
via `odb_transaction_files_write_object_stream()`.

If a "large" blob packfile is written to the ODB transaction temporary
directory after other loose objects, the ODB transaction fails to commit
as a result of the temporary directory being migrated prior to the
packfile being flushed. Fix this bug by always flushing the packfile
transaction before objects are migrated to the main ODB.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object-file.c

diff --git a/object-file.c b/object-file.c
index 0f123b7..210984f 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1262,6 +1262,8 @@ static int odb_transaction_files_commit(struct odb_transaction *base)
 		container_of(base, struct odb_transaction_files, base);
 	int have_packfile = !!transaction->packfile.f;
 
+	flush_packfile_transaction(transaction);
+
 	if (transaction->objdir) {
 		struct strbuf temp_path = STRBUF_INIT;
 		struct tempfile *temp;
@@ -1292,8 +1294,6 @@ static int odb_transaction_files_commit(struct odb_transaction *base)
 		transaction->objdir = NULL;
 	}
 
-	flush_packfile_transaction(transaction);
-
 	if (have_packfile)
 		odb_reprepare(transaction->base.source->odb);
 

t/t1050-large.sh

diff --git a/t/t1050-large.sh b/t/t1050-large.sh
index d295c26..9523345 100755
--- a/t/t1050-large.sh
+++ b/t/t1050-large.sh
@@ -87,6 +87,23 @@
 	test $count = 1
 '
 
+test_expect_success 'add large file with loose object in batch fsync' '
+	test_when_finished "rm -rf batch" &&
+	git init batch &&
+	(
+		cd batch &&
+		git config core.bigFileThreshold 5 &&
+		echo foo >1-small &&
+		echo foobar >2-large &&
+
+		git -c core.fsync=loose-object -c core.fsyncMethod=batch \
+			add 1-small 2-large &&
+
+		git cat-file -e :1-small &&
+		git cat-file -e :2-large
+	)
+'
+
 test_expect_success 'checkout a large file' '
 	large1=$(git rev-parse :large1) &&
 	git update-index --add --cacheinfo 100644 $large1 another &&