Re: [PATCH 2/2] overlay: remove dir which contains whiteout from lower dir

[Eryu Guan <eguan@redhat.com>]

On Thu, Jun 30, 2016 at 03:41:01PM +0800, Xiong Zhou wrote:
> On Wed, Jun 29, 2016 at 09:39:34PM +0800, Eryu Guan wrote:
> > Test the removal of a dir which contains whiteout from lower dir,
> > which could crash the kernel.
> > 
> > The following kernel commit fixed this issue
> > 84889d4 ovl: check dentry positiveness in ovl_cleanup_whiteouts()
> 
> Tested and ack these 2 cases.
> 
> One minor thought down there.

Thanks!

> 
> 
> > 
> > Signed-off-by: Eryu Guan <eguan@redhat.com>
> > ---
> >  tests/overlay/010     | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/overlay/010.out |  2 ++
> >  tests/overlay/group   |  1 +
> >  3 files changed, 81 insertions(+)
> >  create mode 100755 tests/overlay/010
> >  create mode 100644 tests/overlay/010.out
> > 
> > diff --git a/tests/overlay/010 b/tests/overlay/010
> > new file mode 100755
> > index 0000000..5d1c2bd
> > --- /dev/null
> > +++ b/tests/overlay/010
> > @@ -0,0 +1,78 @@
> > +#! /bin/bash
> > +# FS QA Test 010
> > +#
> > +# Remove dir which contains whiteout from lower dir.
> > +#
> > +# The following kernel commit fixed the kernel crash on the removal
> > +# 84889d4 ovl: check dentry positiveness in ovl_cleanup_whiteouts()
> > +#
> > +#-----------------------------------------------------------------------
> > +# Copyright (c) 2016 Red Hat Inc.  All Rights Reserved.
> > +#
> > +# This program is free software; you can redistribute it and/or
> > +# modify it under the terms of the GNU General Public License as
> > +# published by the Free Software Foundation.
> > +#
> > +# This program is distributed in the hope that it would be useful,
> > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > +# GNU General Public License for more details.
> > +#
> > +# You should have received a copy of the GNU General Public License
> > +# along with this program; if not, write the Free Software Foundation,
> > +# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> > +#-----------------------------------------------------------------------
> > +#
> > +
> > +seq=`basename $0`
> > +seqres=$RESULT_DIR/$seq
> > +echo "QA output created by $seq"
> > +
> > +here=`pwd`
> > +tmp=/tmp/$$
> > +status=1	# failure is the default!
> > +trap "_cleanup; exit \$status" 0 1 2 3 15
> > +
> > +_cleanup()
> > +{
> > +	cd /
> > +	rm -f $tmp.*
> > +}
> > +
> > +# get standard environment, filters and checks
> > +. ./common/rc
> > +. ./common/filter
> > +
> > +rm -f $seqres.full
> > +
> > +# real QA test starts here
> > +_supported_fs overlay
> > +_supported_os Linux
> > +_require_scratch
> > +
> > +# Remove all files from previous tests
> > +_scratch_mkfs
> > +
> > +# Need two lower dirs in this test, and we mount overlay ourselves,
> > +# create upper and workdir as well
> > +lowerdir1=$SCRATCH_DEV/$OVERLAY_LOWER_DIR.1
> > +lowerdir2=$SCRATCH_DEV/$OVERLAY_LOWER_DIR.2
> > +upperdir=$SCRATCH_DEV/$OVERLAY_UPPER_DIR
> > +workdir=$SCRATCH_DEV/$OVERLAY_WORK_DIR
> > +mkdir -p $lowerdir1 $lowerdir2 $upperdir $workdir
> > +
> > +# One lowerdir contains test dir and test files, the other contains whiteout
> > +mkdir -p $lowerdir1/testdir $lowerdir2/testdir
> > +touch $lowerdir1/testdir/a $lowerdir1/testdir/b
> > +mknod $lowerdir2/testdir/a c 0 0
> > +
> > +# Mount overlayfs and remove testdir, which led to kernel crash
> > +$MOUNT_PROG -t overlay -o lowerdir=$lowerdir2:$lowerdir1 \
> > +	    -o upperdir=$upperdir,workdir=$workdir \
> > +	    $SCRATCH_DEV $SCRATCH_MNT
> > +rm -rf $SCRATCH_MNT/testdir
> 
> sleep 1 second here ?  Or we could panic after "Pass all 1 tests"
> printed. [untested..]

I think this is fine. Latest upstream kernel has this bug fixed, we
don't want to waste extra second waiting for it to "fail". And if it
crashed the kernel, we have to looked at it anyway and would find it is
this test triggered the crash easily.

Thanks,
Eryu