Re: [PATCH 22/33] generic/631: don't run test if we can't mount overlayfs

Amir Goldstein
2025-11-06T09:23:19Z

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On Thu, Nov 6, 2025 at 12:12 AM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Thu, Oct 30, 2025 at 12:35:03PM +0100, Amir Goldstein wrote:
> > On Tue, Oct 28, 2025 at 06:26:09PM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <djwong@kernel.org>
> > >
> > > This test fails on fuse2fs with the following:
> > >
> > > +mount: /opt/merged0: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error.
> > > + dmesg(1) may have more information after failed mount system call.
> > >
> > > dmesg logs the following:
> > >
> > > [ 764.775172] overlayfs: upper fs does not support tmpfile.
> > > [ 764.777707] overlayfs: upper fs does not support RENAME_WHITEOUT.
> > >
> > > From this, it's pretty clear why the test fails -- overlayfs checks that
> > > the upper filesystem (fuse2fs) supports RENAME_WHITEOUT and O_TMPFILE.
> > > fuse2fs doesn't support either of these, so the mount fails and then the
> > > test goes wild.
> > >
> > > Instead of doing that, let's do an initial test mount with the same
> > > options as the workers, and _notrun if that first mount doesn't succeed.
> > >
> > > Fixes: 210089cfa00315 ("generic: test a deadlock in xfs_rename when whiteing out files")
> > > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > > ---
> > > tests/generic/631 | 22 ++++++++++++++++++++++
> > > 1 file changed, 22 insertions(+)
> > >
> > >
> > > diff --git a/tests/generic/631 b/tests/generic/631
> > > index 72bf85e30bdd4b..64e2f911fdd10e 100755
> > > --- a/tests/generic/631
> > > +++ b/tests/generic/631
> > > @@ -64,6 +64,26 @@ stop_workers() {
> > > done
> > > }
> > >
> > > +require_overlayfs() {
> > > + local tag="check"
> > > + local mergedir="$SCRATCH_MNT/merged$tag"
> > > + local l="lowerdir=$SCRATCH_MNT/lowerdir:$SCRATCH_MNT/lowerdir1"
> > > + local u="upperdir=$SCRATCH_MNT/upperdir$tag"
> > > + local w="workdir=$SCRATCH_MNT/workdir$tag"
> > > + local i="index=off"
> > > +
> > > + rm -rf $SCRATCH_MNT/merged$tag
> > > + rm -rf $SCRATCH_MNT/upperdir$tag
> > > + rm -rf $SCRATCH_MNT/workdir$tag
> > > + mkdir $SCRATCH_MNT/merged$tag
> > > + mkdir $SCRATCH_MNT/workdir$tag
> > > + mkdir $SCRATCH_MNT/upperdir$tag
> > > +
> > > + _mount -t overlay overlay -o "$l,$u,$w,$i" $mergedir || \
> > > + _notrun "cannot mount overlayfs"
> > > + umount $mergedir
> > > +}
> > > +
> > > worker() {
> > > local tag="$1"
> > > local mergedir="$SCRATCH_MNT/merged$tag"
> > > @@ -91,6 +111,8 @@ worker() {
> > > rm -f $SCRATCH_MNT/workers/$tag
> > > }
> > >
> > > +require_overlayfs
> > > +
> > > for i in $(seq 0 $((4 + LOAD_FACTOR)) ); do
> > > worker $i &
> > > done
> > >
> >
> > I agree in general, but please consider this (untested) cleaner patch
>
> Yes, this works too. Since this is your code, could you send it to the
> list with a proper commit message (or even just copy mine) and then I
> can ack it?
>

Attached.
Now it's even tested.

I put you down as Suggested-by.
Feel free to choose your own roles...

Thanks,
Amir.

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From dc31352d6c926e0f6da6238eccbcaa96b1fb89c2 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 30 Oct 2025 12:24:21 +0100
Subject: [PATCH] generic/631: don't run test if we can't mount overlayfs

This test fails on fuse2fs with the following:

mount: /opt/merged0: wrong fs type, bad option, bad superblock on overlay,
missing codepage or helper program, or other error.
dmesg(1) may have more information after failed mount system call.

dmesg logs the following:

[ 764.775172] overlayfs: upper fs does not support tmpfile.
[ 764.777707] overlayfs: upper fs does not support RENAME_WHITEOUT.

From this, it's pretty clear why the test fails -- overlayfs checks that
the upper filesystem (fuse2fs) supports RENAME_WHITEOUT and O_TMPFILE.
fuse2fs doesn't support either of these, so the mount fails and then the
test goes wild.

Instead of doing that, let's do an initial test mount with the same
options as the workers, and _notrun if that first mount doesn't succeed.

Fixes: 210089cfa00315 ("generic: test a deadlock in xfs_rename when whiteing out files")
Suggested-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
tests/generic/631 | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/tests/generic/631 b/tests/generic/631
index c38ab771..7dc335aa 100755
--- a/tests/generic/631
+++ b/tests/generic/631
@@ -46,7 +46,6 @@ _require_extra_fs overlay

_scratch_mkfs >> $seqres.full
_scratch_mount
-_supports_filetype $SCRATCH_MNT || _notrun "overlayfs test requires d_type"

mkdir $SCRATCH_MNT/lowerdir
mkdir $SCRATCH_MNT/lowerdir1
@@ -64,7 +63,7 @@ stop_workers() {
done
}

-worker() {
+mount_overlay() {
local tag="$1"
local mergedir="$SCRATCH_MNT/merged$tag"
local l="lowerdir=$SCRATCH_MNT/lowerdir:$SCRATCH_MNT/lowerdir1"
@@ -72,25 +71,43 @@ worker() {
local w="workdir=$SCRATCH_MNT/workdir$tag"
local i="index=off"

+ rm -rf $SCRATCH_MNT/merged$tag
+ rm -rf $SCRATCH_MNT/upperdir$tag
+ rm -rf $SCRATCH_MNT/workdir$tag
+ mkdir $SCRATCH_MNT/merged$tag
+ mkdir $SCRATCH_MNT/workdir$tag
+ mkdir $SCRATCH_MNT/upperdir$tag
+
+ mount -t overlay overlay -o "$l,$u,$w,$i" "$mergedir"
+}
+
+unmount_overlay() {
+ local tag="$1"
+ local mergedir="$SCRATCH_MNT/merged$tag"
+
+ _unmount $mergedir
+}
+
+worker() {
+ local tag="$1"
+ local mergedir="$SCRATCH_MNT/merged$tag"
+
touch $SCRATCH_MNT/workers/$tag
while test -e $SCRATCH_MNT/running; do
- rm -rf $SCRATCH_MNT/merged$tag
- rm -rf $SCRATCH_MNT/upperdir$tag
- rm -rf $SCRATCH_MNT/workdir$tag
- mkdir $SCRATCH_MNT/merged$tag
- mkdir $SCRATCH_MNT/workdir$tag
- mkdir $SCRATCH_MNT/upperdir$tag
-
- mount -t overlay overlay -o "$l,$u,$w,$i" $mergedir
+ mount_overlay $tag
mv $mergedir/etc/access.conf $mergedir/etc/access.conf.bak
touch $mergedir/etc/access.conf
mv $mergedir/etc/access.conf $mergedir/etc/access.conf.bak
touch $mergedir/etc/access.conf
- _unmount $mergedir
+ unmount_overlay $tag
done
rm -f $SCRATCH_MNT/workers/$tag
}

+mount_overlay check || \
+ _notrun "cannot mount overlayfs with underlying filesystem $FSTYP"
+unmount_overlay check
+
for i in $(seq 0 $((4 + LOAD_FACTOR)) ); do
worker $i &
done
--
2.51.1