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

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Nov 06, 2025 at 10:23:04AM +0100, Amir Goldstein wrote:
> 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.

> 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>

Works for me,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  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
>