| Message ID | 20231228025537.28807-1-wegao@suse.com |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v3] move_mount03: check allow to mount beneath top mount | expand |
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, > +};
> 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? +1 > > + 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. What would do the second mount? move_mount() ? There are SAFE_UMOUNT() in the end of the testing function, that's why usually even these 2 SAFE_UMOUNT() aren't needed (but obviously we need to add them if SAFE_TOUCH() or something quits testing early): move_mount03.c:92: TPASS: move_mount(fda, "", fdb, "", MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH) passed move_mount03.c:98: TPASS: access(DIRB "/B", F_OK) passed move_mount03.c:99: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B move_mount03.c:100: TPASS: access(DIRB "/A", F_OK) passed move_mount03.c:102: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B move_mount03.c:103: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_A tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_A tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_B Kind regards, Petr > > +} > > + > > +static struct tst_test test = { > > + .test_all = run, > > + .needs_root = 1, > > + .min_kver = "6.5.0", > > + .needs_tmpdir = 1, > > + .setup = setup, > > + .cleanup = cleanup, > > +};
On 20. 03. 24 8:43, Petr Vorel wrote: >> On 28. 12. 23 3:55, Wei Gao via ltp wrote: >>> +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. > > What would do the second mount? move_mount() ? > > There are SAFE_UMOUNT() in the end of the testing function, that's why usually > even these 2 SAFE_UMOUNT() aren't needed (but obviously we need to add them if > SAFE_TOUCH() or something quits testing early): > > move_mount03.c:92: TPASS: move_mount(fda, "", fdb, "", MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH) passed > move_mount03.c:98: TPASS: access(DIRB "/B", F_OK) passed > move_mount03.c:99: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B > move_mount03.c:100: TPASS: access(DIRB "/A", F_OK) passed > move_mount03.c:102: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B > move_mount03.c:103: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_A > tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_A > tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_B Yes, open_tree() was called with OPEN_TREE_CLONE so after move_mount(), the mounts look like this: - tmpfs[1] at DIRA - tmpfs[1] at DIRB - tmpfs[2] at DIRB If either SAFE_CLOSE() immediately after move_mount() fails, cleanup() will unmount tmpfs[1] from DIRA and tmpfs[2] from DIRB but leave tmpfs[1] mounted at DIRB.
> On 20. 03. 24 8:43, Petr Vorel wrote: > > > On 28. 12. 23 3:55, Wei Gao via ltp wrote: > > > > +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. > > What would do the second mount? move_mount() ? > > There are SAFE_UMOUNT() in the end of the testing function, that's why usually > > even these 2 SAFE_UMOUNT() aren't needed (but obviously we need to add them if > > SAFE_TOUCH() or something quits testing early): > > move_mount03.c:92: TPASS: move_mount(fda, "", fdb, "", MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH) passed > > move_mount03.c:98: TPASS: access(DIRB "/B", F_OK) passed > > move_mount03.c:99: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B > > move_mount03.c:100: TPASS: access(DIRB "/A", F_OK) passed > > move_mount03.c:102: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B > > move_mount03.c:103: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_A > > tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_A > > tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_B > Yes, open_tree() was called with OPEN_TREE_CLONE so after move_mount(), the > mounts look like this: > - tmpfs[1] at DIRA > - tmpfs[1] at DIRB > - tmpfs[2] at DIRB > If either SAFE_CLOSE() immediately after move_mount() fails, cleanup() will > unmount tmpfs[1] from DIRA and tmpfs[2] from DIRB but leave tmpfs[1] mounted > at DIRB. @Martin Thanks! @Wai Please send another version. Kind regards, Petr
> On 20. 03. 24 8:43, Petr Vorel wrote: > > > On 28. 12. 23 3:55, Wei Gao via ltp wrote: > > > > +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. > > What would do the second mount? move_mount() ? > > There are SAFE_UMOUNT() in the end of the testing function, that's why usually > > even these 2 SAFE_UMOUNT() aren't needed (but obviously we need to add them if > > SAFE_TOUCH() or something quits testing early): > > move_mount03.c:92: TPASS: move_mount(fda, "", fdb, "", MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH) passed > > move_mount03.c:98: TPASS: access(DIRB "/B", F_OK) passed > > move_mount03.c:99: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B > > move_mount03.c:100: TPASS: access(DIRB "/A", F_OK) passed > > move_mount03.c:102: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_B > > move_mount03.c:103: TINFO: Umounting /tmp/LTP_movqeTZGu/LTP_DIR_A > > tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_A > > tst_device.c:442: TINFO: No device is mounted at /tmp/LTP_movqeTZGu/LTP_DIR_B > Yes, open_tree() was called with OPEN_TREE_CLONE so after move_mount(), the > mounts look like this: > - tmpfs[1] at DIRA > - tmpfs[1] at DIRB > - tmpfs[2] at DIRB > If either SAFE_CLOSE() immediately after move_mount() fails, cleanup() will > unmount tmpfs[1] from DIRA and tmpfs[2] from DIRB but leave tmpfs[1] mounted > at DIRB. Correct. Thanks! Kind regards, Petr
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)); */ + 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)); + 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); +} + +static struct tst_test test = { + .test_all = run, + .needs_root = 1, + .min_kver = "6.5.0", + .needs_tmpdir = 1, + .setup = setup, + .cleanup = cleanup, +};
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