[LTP] [PATCH v3] move_mount03: check allow to mount beneath top mount
Martin Doucha
mdoucha@suse.cz
Wed Mar 6 18:24:10 CET 2024
Hi,
some comments below.
On 28. 12. 23 3:55, Wei Gao via ltp wrote:
> Signed-off-by: Wei Gao <wegao@suse.com>
> ---
> include/lapi/fsmount.h | 4 +
> runtest/syscalls | 1 +
> .../kernel/syscalls/move_mount/.gitignore | 1 +
> .../kernel/syscalls/move_mount/move_mount03.c | 128 ++++++++++++++++++
> 4 files changed, 134 insertions(+)
> create mode 100644 testcases/kernel/syscalls/move_mount/move_mount03.c
>
> diff --git a/include/lapi/fsmount.h b/include/lapi/fsmount.h
> index 07eb42ffa..216e966c7 100644
> --- a/include/lapi/fsmount.h
> +++ b/include/lapi/fsmount.h
> @@ -115,6 +115,10 @@ static inline int mount_setattr(int dirfd, const char *from_pathname, unsigned i
> }
> #endif /* HAVE_MOUNT_SETATTR */
>
> +#ifndef MOVE_MOUNT_BENEATH
> +#define MOVE_MOUNT_BENEATH 0x00000200
> +#endif /* MOVE_MOUNT_BENEATH */
> +
> /*
> * New headers added in kernel after 5.2 release, create them for old userspace.
> */
> diff --git a/runtest/syscalls b/runtest/syscalls
> index b1125dd75..04b758fd9 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -824,6 +824,7 @@ mount_setattr01 mount_setattr01
>
> move_mount01 move_mount01
> move_mount02 move_mount02
> +move_mount03 move_mount03
>
> move_pages01 move_pages01
> move_pages02 move_pages02
> diff --git a/testcases/kernel/syscalls/move_mount/.gitignore b/testcases/kernel/syscalls/move_mount/.gitignore
> index 83ae40145..ddfe10128 100644
> --- a/testcases/kernel/syscalls/move_mount/.gitignore
> +++ b/testcases/kernel/syscalls/move_mount/.gitignore
> @@ -1,2 +1,3 @@
> /move_mount01
> /move_mount02
> +/move_mount03
> diff --git a/testcases/kernel/syscalls/move_mount/move_mount03.c b/testcases/kernel/syscalls/move_mount/move_mount03.c
> new file mode 100644
> index 000000000..fff95c50b
> --- /dev/null
> +++ b/testcases/kernel/syscalls/move_mount/move_mount03.c
> @@ -0,0 +1,128 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2023 Christian Brauner <brauner@kernel.org>
> + * Copyright (c) 2023 Wei Gao <wegao@suse.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * Test allow to mount beneath top mount feature
> + */
> +
> +/*
> + * Test create for following commit:
> + * commit 6ac392815628f317fcfdca1a39df00b9cc4ebc8b
> + * Author: Christian Brauner <brauner@kernel.org>
> + * Date: Wed May 3 13:18:42 2023 +0200
> + * fs: allow to mount beneath top mount
> + *
> + * Above commit has heavily commented but i found following commit
> + * contain simple summary of this feature for easy understanding:
> + *
> + * commit c0a572d9d32fe1e95672f24e860776dba0750a38
> + * Author: Linus Torvalds <torvalds@linux-foundation.org>
> + * TL;DR:
> + *
> + * > mount -t ext4 /dev/sda /mnt
> + * |
> + * --/mnt /dev/sda ext4
> + *
> + * > mount --beneath -t xfs /dev/sdb /mnt
> + * |
> + * --/mnt /dev/sdb xfs
> + * --/mnt /dev/sda ext4
> + *
> + * > umount /mnt
> + * |
> + * --/mnt /dev/sdb xfs
> + *
> + * So base above scenario design following scenario for LTP check:
> + *
> + * > mount -t tmpfs /DIRA
> + * |
> + * --/DIRA(create A file within DIRA)
> + *
> + * > mount -t tmpfs /DIRB
> + * |
> + * --/DIRA(create B file within DIRB)
> + *
> + * > move_mount --beneath /DIRA /DIRB
> + * |
> + * --/mnt /DIRA /DIRB
> + * --/mnt /DIRB
> + *
> + * If you check content of /DIRB, you can see file B
> + *
> + * > umount /DIRB
> + * |
> + * --/mnt /DIRA /DIRB
> + * Check content of /DIRB, you can see file A exist since
> + * current /DIRB mount source is already become /DIRA
> + *
> + * See also:
> + * https://lwn.net/Articles/930591/
> + * https://github.com/brauner/move-mount-beneath
> + */
> +
> +#include <stdio.h>
> +
> +#include "tst_test.h"
> +#include "lapi/fsmount.h"
> +#include "lapi/sched.h"
> +
> +#define DIRA "LTP_DIR_A"
> +#define DIRB "LTP_DIR_B"
> +
> +static void run(void)
> +{
> + int fda, fdb;
> +
> + SAFE_MOUNT("none", DIRA, "tmpfs", 0, 0);
> + SAFE_MOUNT("none", DIRB, "tmpfs", 0, 0);
> + SAFE_TOUCH(DIRA "/A", 0, NULL);
> + SAFE_TOUCH(DIRB "/B", 0, NULL);
> +
> + /* TEST(fda = open_tree(AT_FDCWD, DIRA, OPEN_TREE_CLOEXEC | OPEN_TREE_CLONE)); */
Is the comment needed?
> + fda = open_tree(AT_FDCWD, DIRA, OPEN_TREE_CLOEXEC | OPEN_TREE_CLONE);
> + if (fda == -1)
> + tst_brk(TBROK | TERRNO, "open_tree() failed");
> +
> + fdb = SAFE_OPEN(DIRB, O_PATH | O_NOFOLLOW, 0666);
> + TST_EXP_PASS(move_mount(fda, "", fdb, "",
> + MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH |
> + MOVE_MOUNT_T_EMPTY_PATH));
> + SAFE_CLOSE(fda);
> + SAFE_CLOSE(fdb);
> +
> + TST_EXP_PASS(access(DIRB "/B", F_OK));
It'd also make sense the check here that file A still exists in DIRA but
not in DIRB.
> + SAFE_UMOUNT(DIRB);
> + TST_EXP_PASS(access(DIRB "/A", F_OK));
> +
> + SAFE_UMOUNT(DIRB);
> + SAFE_UMOUNT(DIRA);
> +}
> +
> +static void setup(void)
> +{
> + SAFE_MKDIR(DIRA, 0777);
> + SAFE_MKDIR(DIRB, 0777);
> +}
> +
> +static void cleanup(void)
> +{
> + if (tst_is_mounted_at_tmpdir(DIRA))
> + SAFE_UMOUNT(DIRA);
> +
> + if (tst_is_mounted_at_tmpdir(DIRB))
> + SAFE_UMOUNT(DIRB);
I believe that DIRB may need to be unmounted twice here. Also please
close fda and fdb here if they're still open.
> +}
> +
> +static struct tst_test test = {
> + .test_all = run,
> + .needs_root = 1,
> + .min_kver = "6.5.0",
> + .needs_tmpdir = 1,
> + .setup = setup,
> + .cleanup = cleanup,
> +};
--
Martin Doucha mdoucha@suse.cz
SW Quality Engineer
SUSE LINUX, s.r.o.
CORSO IIa
Krizikova 148/34
186 00 Prague 8
Czech Republic
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