[LTP] [PATCH] fanotify: Fix broken tests due to fanotify_events_supported_by_kernel()

[Petr Vorel]

Hi Jan, Amir,

> On Mon 27-11-23 19:40:14, Amir Goldstein wrote:
> > On Mon, Nov 27, 2023 at 5:40 PM Jan Kara <jack@suse.cz> wrote:

> > > When LTP test is run with CWD in btrfs subvolume, tests like fanotify16
> > > fail with:

> > > fanotify.h:169: TBROK: fanotify_mark (3, FAN_MARK_ADD, ..., AT_FDCWD, ".") failed: EXDEV (18)

> > > This is because fanotify_events_supported_by_kernel() try to place a
> > > mark onto CWD and that is forbidden for btrfs subvolumes. Change
> > > fanotify_events_supported_by_kernel() to use "/" instead of "." which
> > > has higher chances of working for btrfs.


> > FWIW, "." in setup() is usually a tempdir (under LTP temp root)
> > So I'm not sure that "/" is a better choice than ".".
> > At least the LTP temp dir is configurable.
> > and no reason that "/" is not a btrfs subvol inside a container...

> Yeah, that's a good point. I was thinking it need not be so simple but
> wanted something to start a discussion :)

The variable is TMPDIR (all variables are printed with -h, e.g. ./fanotify01 -h).
I was expecting this would be a problem, but instead the test was broken on
Tumbleweed with the default TMPDIR value /tmp.

> > FYI, in this branch:
> > https://github.com/amir73il/ltp/commits/fanotify_fsid

FYI the first commit breaks at least vfat on fanotify13
# LTP_SINGLE_FS_TYPE=vfat ./fanotify13
...
tst_test.c:1650: TINFO: === Testing on vfat ===
tst_test.c:1105: TINFO: Formatting /dev/loop1 with vfat opts='' extra opts=''
tst_test.c:1119: TINFO: Mounting /dev/loop1 to /tmp/LTP_fanM9wLom/mntpoint fstyp=vfat flags=0
fanotify13.c:152: TINFO: Test #0.1: FAN_REPORT_FID with mark flag: FAN_MARK_INODE
fanotify13.c:157: TCONF: overlayfs not supported on vfat
fanotify13.c:152: TINFO: Test #1.1: FAN_REPORT_FID with mark flag: FAN_MARK_INODE
fanotify13.c:157: TCONF: overlayfs not supported on vfat
fanotify13.c:152: TINFO: Test #2.1: FAN_REPORT_FID with mark flag: FAN_MARK_MOUNT
fanotify13.c:157: TCONF: overlayfs not supported on vfat
fanotify13.c:152: TINFO: Test #3.1: FAN_REPORT_FID with mark flag: FAN_MARK_MOUNT
fanotify13.c:157: TCONF: overlayfs not supported on vfat
fanotify13.c:152: TINFO: Test #4.1: FAN_REPORT_FID with mark flag: FAN_MARK_FILESYSTEM
fanotify13.c:157: TCONF: overlayfs not supported on vfat
fanotify13.c:152: TINFO: Test #5.1: FAN_REPORT_FID with mark flag: FAN_MARK_FILESYSTEM
fanotify13.c:157: TCONF: overlayfs not supported on vfat
tst_device.c:408: TINFO: umount('mntpoint') failed with EBUSY, try  1...
tst_device.c:412: TINFO: Likely gvfsd-trash is probing newly mounted fs, kill it to speed up tests.
tst_device.c:408: TINFO: umount('mntpoint') failed with EBUSY, try  2...
tst_device.c:408: TINFO: umount('mntpoint') failed with EBUSY, try  3...
...
tst_device.c:408: TINFO: umount('mntpoint') failed with EBUSY, try 50...
tst_device.c:419: TWARN: Failed to umount('mntpoint') after 50 retries
tst_test.c:1650: TINFO: === Testing on exfat ===
tst_test.c:1105: TINFO: Formatting /dev/loop1 with exfat opts='' extra opts=''
tst_test.c:1119: TINFO: Mounting /dev/loop1 to /tmp/LTP_fanM9wLom/mntpoint fstyp=exfat flags=0
tst_test.c:1119: TINFO: Trying FUSE...
FUSE exfat 1.4.0 (libfuse2)
fuse: mount failed: Device or resource busy
tst_test.c:1119: TBROK: mount.exfat failed with 256

HINT: You _MAY_ be missing kernel fixes:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c285a2f01d69
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bc2473c90fca


> > I have already implemented fanotify_flags_supported_on_fs()
> > which can be used to test support for an event/mark on a specific path.

> > I did not make the change in fanotify16.c to use
> > fanotify_flags_supported_on_fs() instead of
> > fanotify_{mark,events}_supported_by_kernel() but it would be trivial to do.

> OK, this is probably a more robust idea so that we test all the features
> against a path we are then actually going to use for testing. I'll pick the
> commit "fanotify: Generalize helper fanotify_flags_supported_on_fs()" from
> your branch and rework the fix based on that tomorrow. Thanks!

Great!

Thanks a lot to you both!

Kind regards,
Petr

> 								Honza