btrfs-progs: fsck-tests: corrupt and detect dir_item name (with fix)

new file mode 100755
index 0000000..6e76513
@@ -0,0 +1,41 @@
+#!/bin/bash
+
+source $TOP/tests/common
+
+check_prereq btrfs-corrupt-block
+check_prereq mkfs.btrfs
+check_prereq btrfs
+
+setup_root_helper
+prepare_test_dev 512M
+
+ROOT_NODE=256
+BTRFS_DIR_ITEM_KEY=84
+
+# test whether fsck can detect a corrupted dir item name
+test_dir_item_name_field()
+{
+	run_check $SUDO_HELPER $TOP/mkfs.btrfs -f $TEST_DEV
+
+	run_check_mount_test_dev
+	run_check $SUDO_HELPER touch $TEST_MNT/testfile.txt
+
+	run_check_umount_test_dev
+
+	# find key offset
+	key_offset=`$SUDO_HELPER $TOP/btrfs-debug-tree -t FS_TREE $TEST_DEV | \
+	grep -B3 'testfile.txt'  | grep "$ROOT_NODE DIR_ITEM" | \
+	cut -f1 -d')' | awk '{print $6}'`
+
+	key=$ROOT_NODE","$BTRFS_DIR_ITEM_KEY","$key_offset
+
+	# corrupt dir item name
+        run_check $SUDO_HELPER $TOP/btrfs-corrupt-block -D -f name \
+		-K $key $TEST_DEV
+
+	$SUDO_HELPER $TOP/btrfs check $TEST_DEV >& /dev/null && \
+			_fail "btrfs check failed to detect corruption"
+	run_check $SUDO_HELPER $TOP/btrfs check --repair $TEST_DEV
+}
+
+test_dir_item_name_field