[PATCH v4 4/4] selftests/filesystems: add a vfat RENAME_EXCHANGE test

From: Javier Martinez Canillas
Date: Wed Jun 01 2022 - 13:32:41 EST

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 <javierm@xxxxxxxxxx>
Acked-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
---

Changes in v4:
- Add Muhammad Usama Anjum Acked-by tag.

Changes in v3:
- Add a .gitignore for the rename_exchange binary (Muhammad Usama Anjum).
- Include $(KHDR_INCLUDES) instead of hardcoding a relative path in Makefile
(Muhammad Usama Anjum).

Changes in v2:
- Call sync to flush the page cache before checking the file contents
(Alex Larsson).

MAINTAINERS | 1 +
tools/testing/selftests/Makefile | 1 +
.../selftests/filesystems/fat/.gitignore | 2 +
.../selftests/filesystems/fat/Makefile | 7 ++
.../testing/selftests/filesystems/fat/config | 2 +
.../filesystems/fat/rename_exchange.c | 37 +++++++++
.../filesystems/fat/run_fat_tests.sh | 82 +++++++++++++++++++
7 files changed, 132 insertions(+)
create mode 100644 tools/testing/selftests/filesystems/fat/.gitignore
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 4fdbbd6c1984..158771bb7755 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20841,6 +20841,7 @@ M: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
S: Maintained
F: Documentation/filesystems/vfat.rst
F: fs/fat/
+F: tools/testing/selftests/filesystems/fat/

VFIO DRIVER
M: Alex Williamson <alex.williamson@xxxxxxxxxx>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 0aedcd76cf0f..fc59ad849a90 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/.gitignore b/tools/testing/selftests/filesystems/fat/.gitignore
new file mode 100644
index 000000000000..b89920ed841c
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fat/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+rename_exchange
diff --git a/tools/testing/selftests/filesystems/fat/Makefile b/tools/testing/selftests/filesystems/fat/Makefile
new file mode 100644
index 000000000000..902033f6ef09
--- /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 $(KHDR_INCLUDES)
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/filesystems/fat/config b/tools/testing/selftests/filesystems/fat/config
new file mode 100644
index 000000000000..6cf95e787a17
--- /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 000000000000..e488ad354fce
--- /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 <javierm@xxxxxxxxxx>
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+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 000000000000..7f35dc3d15df
--- /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 <javierm@xxxxxxxxxx>
+
+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}" "${new_path}" >/dev/null 2>&1
+ sudo sync -f "${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 sync -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
--
2.36.1