From 6be2d6cd258eef6a8cb4818e73015c499037c5ed Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Thu, 19 May 2022 08:54:10 +0200 Subject: [PATCH] selftests/filesystems: add a vfat RENAME_EXCHANGE test Add a test for the renameat2 RENAME_EXCHANGE support in vfat, but split it in a tool that just does the rename exchange and a script that is run by the kselftests framework on `make TARGETS="filesystems/fat" kselftest`. That way the script can be easily extended to test other file operations. The script creates a 1 MiB disk image, that is then formated with a vfat filesystem and mounted using a loop device. That way all file operations are done on an ephemeral filesystem. Signed-off-by: Javier Martinez Canillas Series-changes: 2 - Call fsync to flush the page cache before checking the file contents (Alex Larsson). Series-cc: Alexander Larsson Series-cc: Peter Jones Series-cc: Lennart Poettering Series-cc: Colin Walters Series-cc: Alberto Ruiz Series-cc: Christian Kellner Series-cc: Chung-Chiang Cheng Series-version: 2 Cover-letter: fat: add support for the renameat2 RENAME_EXCHANGE flag Hello, This series add support for the renameat2 system call RENAME_EXCHANGE flag (which allows to atomically replace two paths) to the vfat filesystem code. There are many use cases for this, but we are particularly interested in making possible for vfat filesystems to be part of OSTree [0] deployments. Currently OSTree relies on symbolic links to make the deployment updates an atomic transactional operation. But RENAME_EXCHANGE could be used [1] to achieve a similar level of robustness when using a vfat filesystem. Patch #1 is just a preparatory patch to introduce the RENAME_EXCHANGE support in patch #2 and finally patch #3 adds some kselftests to test it. This is my first contribution to the fs/* subsystem, so I'm marking this set as RFC, in case I got anything wrong with the patches. But they work correctly on my local testing. [0]: https://github.com/ostreedev/ostree [1]: https://github.com/ostreedev/ostree/issues/1649 END --- MAINTAINERS | 1 + tools/testing/selftests/Makefile | 1 + .../selftests/filesystems/fat/Makefile | 7 ++ .../testing/selftests/filesystems/fat/config | 2 + .../filesystems/fat/rename_exchange.c | 37 +++++++++ .../filesystems/fat/run_fat_tests.sh | 82 +++++++++++++++++++ 6 files changed, 130 insertions(+) create mode 100644 tools/testing/selftests/filesystems/fat/Makefile create mode 100644 tools/testing/selftests/filesystems/fat/config create mode 100644 tools/testing/selftests/filesystems/fat/rename_exchange.c create mode 100755 tools/testing/selftests/filesystems/fat/run_fat_tests.sh diff --git a/MAINTAINERS b/MAINTAINERS index 4fdbbd6c19840b..158771bb775568 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20841,6 +20841,7 @@ M: OGAWA Hirofumi S: Maintained F: Documentation/filesystems/vfat.rst F: fs/fat/ +F: tools/testing/selftests/filesystems/fat/ VFIO DRIVER M: Alex Williamson diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 0aedcd76cf0f72..fc59ad849a90ba 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -16,6 +16,7 @@ TARGETS += exec TARGETS += filesystems TARGETS += filesystems/binderfs TARGETS += filesystems/epoll +TARGETS += filesystems/fat TARGETS += firmware TARGETS += fpu TARGETS += ftrace diff --git a/tools/testing/selftests/filesystems/fat/Makefile b/tools/testing/selftests/filesystems/fat/Makefile new file mode 100644 index 00000000000000..93ee73c16828b4 --- /dev/null +++ b/tools/testing/selftests/filesystems/fat/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0 + +TEST_PROGS := run_fat_tests.sh +TEST_GEN_PROGS_EXTENDED := rename_exchange +CFLAGS += -O2 -g -Wall -I../../../../usr/include/ + +include ../../lib.mk diff --git a/tools/testing/selftests/filesystems/fat/config b/tools/testing/selftests/filesystems/fat/config new file mode 100644 index 00000000000000..6cf95e787a17b5 --- /dev/null +++ b/tools/testing/selftests/filesystems/fat/config @@ -0,0 +1,2 @@ +CONFIG_BLK_DEV_LOOP=y +CONFIG_VFAT_FS=y diff --git a/tools/testing/selftests/filesystems/fat/rename_exchange.c b/tools/testing/selftests/filesystems/fat/rename_exchange.c new file mode 100644 index 00000000000000..e488ad354fce4f --- /dev/null +++ b/tools/testing/selftests/filesystems/fat/rename_exchange.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Program that atomically exchanges two paths using + * the renameat2() system call RENAME_EXCHANGE flag. + * + * Copyright 2022 Red Hat Inc. + * Author: Javier Martinez Canillas + */ + +#define _GNU_SOURCE +#include +#include +#include + +void print_usage(const char *program) +{ + printf("Usage: %s [oldpath] [newpath]\n", program); + printf("Atomically exchange oldpath and newpath\n"); +} + +int main(int argc, char *argv[]) +{ + int ret; + + if (argc != 3) { + print_usage(argv[0]); + exit(EXIT_FAILURE); + } + + ret = renameat2(AT_FDCWD, argv[1], AT_FDCWD, argv[2], RENAME_EXCHANGE); + if (ret) { + perror("rename exchange failed"); + exit(EXIT_FAILURE); + } + + exit(EXIT_SUCCESS); +} diff --git a/tools/testing/selftests/filesystems/fat/run_fat_tests.sh b/tools/testing/selftests/filesystems/fat/run_fat_tests.sh new file mode 100755 index 00000000000000..ce82de4f9cd6b1 --- /dev/null +++ b/tools/testing/selftests/filesystems/fat/run_fat_tests.sh @@ -0,0 +1,82 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Run filesystem operations tests on an 1 MiB disk image that is formatted with +# a vfat filesystem and mounted in a temporary directory using a loop device. +# +# Copyright 2022 Red Hat Inc. +# Author: Javier Martinez Canillas + +set -e +set -u +set -o pipefail + +BASE_DIR="$(dirname $0)" +TMP_DIR="$(mktemp -d /tmp/fat_tests_tmp.XXXX)" +IMG_PATH="${TMP_DIR}/fat.img" +MNT_PATH="${TMP_DIR}/mnt" + +cleanup() +{ + mountpoint -q "${MNT_PATH}" && unmount_image + rm -rf "${TMP_DIR}" +} +trap cleanup SIGINT SIGTERM EXIT + +create_loopback() +{ + touch "${IMG_PATH}" + chattr +C "${IMG_PATH}" >/dev/null 2>&1 || true + + truncate -s 1M "${IMG_PATH}" + mkfs.vfat "${IMG_PATH}" >/dev/null 2>&1 +} + +mount_image() +{ + mkdir -p "${MNT_PATH}" + sudo mount -o loop "${IMG_PATH}" "${MNT_PATH}" +} + +rename_exchange_test() +{ + local rename_exchange="${BASE_DIR}/rename_exchange" + local old_path="${MNT_PATH}/old_file" + local new_path="${MNT_PATH}/new_file" + + echo old | sudo tee "${old_path}" >/dev/null 2>&1 + echo new | sudo tee "${new_path}" >/dev/null 2>&1 + sudo "${rename_exchange}" "${old_path}" "${new_path}" >/dev/null 2>&1 + sudo fsync -f "${MNT_PATH}" + grep new "${old_path}" >/dev/null 2>&1 + grep old "${new_path}" >/dev/null 2>&1 +} + +rename_exchange_subdir_test() +{ + local rename_exchange="${BASE_DIR}/rename_exchange" + local dir_path="${MNT_PATH}/subdir" + local old_path="${MNT_PATH}/old_file" + local new_path="${dir_path}/new_file" + + sudo mkdir -p "${dir_path}" + echo old | sudo tee "${old_path}" >/dev/null 2>&1 + echo new | sudo tee "${new_path}" >/dev/null 2>&1 + sudo "${rename_exchange}" "${old_path}" "${new_path}" >/dev/null 2>&1 + sudo fsync -f "${MNT_PATH}" + grep new "${old_path}" >/dev/null 2>&1 + grep old "${new_path}" >/dev/null 2>&1 +} + +unmount_image() +{ + sudo umount "${MNT_PATH}" &> /dev/null +} + +create_loopback +mount_image +rename_exchange_test +rename_exchange_subdir_test +unmount_image + +exit 0