Re: [PATCH v3] generic: test small swapfile without page-aligned contiguous blocks

[Zorro Lang <zlang@redhat.com>]

On Sat, Jun 19, 2021 at 06:40:59AM +0530, riteshh wrote:
> On 21/06/17 01:05PM, Zorro Lang wrote:
> > If a swapfile doesn't contain even a single page-aligned contiguous
> > range of blocks, it's an invalid swapfile, and might cause kernel
> > issue. This case covered commit 5808fecc5723 ("iomap: Fix negative
> > assignment to unsigned sis->pages in iomap_swapfile_activate").
> 
> Hi Zorro,
> 
> Sorry for getting late on this. So can you reproduce the issue described in the
> patch on latest upstream kernel too w/o the above kernel fix with this fstest?
> 
> So how I remember it, this fix on older kernel prevented a kernel panic.
> But on latest kernel it prevented from adding a fake hugesize swapfile.
> In your test, I don't see a test for checking whether the swapfile which was
> getting added is of the appropriate size or not. Note that this was only
> happening with a tiny swapfile of 1 blocksize(totalsize) only.
> 
> If you take a look at [1], we are also checking for
> +	# error case
> +	if [ $swapsize -gt $filesize ]; then
> +		status=1
> +		echo "Allocated swap size($swapsize) cannot be greater than swapfile size($filesize)"
> +	fi
> 
> [1]: https://patchwork.kernel.org/project/fstests/patch/e1f9798462ef60648db24b6291e1b149b114f2f2.1622105066.git.riteshh@linux.ibm.com/

Hi Ritesh,

Thanks for your reviewing, you're right, I didn't test on upstream kernel. I just
tried to reproduce that panic on old kernel (of RHEL-8).

I'll give upstream kernel a test, then change this case according to your
suggestion.

Thanks,
Zorro

> 
> -ritesh
> 
> 
> >
> > Signed-off-by: Zorro Lang <zlang@redhat.com>
> > ---
> >
> > Thanks the review from Darrick, V3 did below changes:
> > 1) Add _require_xfs_io_command fcollapse
> > 2) Change the notrun output if block size isn't 1024.
> >
> > Thanks,
> > Zorro
> >
> >  tests/generic/639     | 83 +++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/639.out |  2 ++
> >  tests/generic/group   |  1 +
> >  3 files changed, 86 insertions(+)
> >  create mode 100755 tests/generic/639
> >  create mode 100644 tests/generic/639.out
> >
> > diff --git a/tests/generic/639 b/tests/generic/639
> > new file mode 100755
> > index 00000000..c8d0c6c5
> > --- /dev/null
> > +++ b/tests/generic/639
> > @@ -0,0 +1,83 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2021 Red Hat Inc.  All Rights Reserved.
> > +#
> > +# FS QA Test No. 639
> > +#
> > +# Test small swapfile which doesn't contain even a single page-aligned contiguous
> > +# range of blocks. This case covered commit 5808fecc5723 ("iomap: Fix negative
> > +# assignment to unsigned sis->pages in iomap_swapfile_activate").
> > +#
> > +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
> > +
> > +# remove previous $seqres.full before test
> > +rm -f $seqres.full
> > +
> > +# real QA test starts here
> > +_supported_fs generic
> > +_require_scratch
> > +_require_scratch_swapfile
> > +_require_test_program mkswap
> > +_require_test_program swapon
> > +_require_xfs_io_command fcollapse
> > +
> > +make_unaligned_swapfile()
> > +{
> > +	local fname=$1
> > +	local n=$((psize / bsize - 1))
> > +
> > +	# Make sure the swapfile doesn't contain even a single page-aligned
> > +	# contiguous range of blocks. This's necessary to cover the bug
> > +	$XFS_IO_PROG -f -t -c "pwrite 0 $(((psize + bsize) * n))" $fname >> $seqres.full 2>&1
> > +	for((i=1; i<=n; i++));do
> > +		$XFS_IO_PROG -c "fcollapse $(((psize - bsize) * i)) $bsize" $fname
> > +	done
> > +	chmod 0600 $fname
> > +	$CHATTR_PROG +C $fname > /dev/null 2>&1
> > +	$here/src/mkswap $fname
> > +}
> > +
> > +_scratch_mkfs >> $seqres.full 2>&1
> > +_scratch_mount
> > +psize=`get_page_size`
> > +bsize=`_get_file_block_size $SCRATCH_MNT`
> > +# Due to we need page-unaligned blocks, so blocksize < pagesize is necessary.
> > +# If not, try to make a smaller enough block size
> > +if [ $bsize -ge $psize ];then
> > +	_scratch_unmount
> > +	_scratch_mkfs_blocksized 1024 >> $seqres.full 2>&1
> > +	if [ $? -ne 0 ];then
> > +		_notrun "Can't make filesystem block size < page size."
> > +	fi
> > +	_scratch_mount
> > +	bsize=`_get_file_block_size $SCRATCH_MNT`
> > +	if [ $bsize -ne 1024 ];then
> > +		_notrun "Can't force 1024-byte file block size."
> > +	fi
> > +fi
> > +swapfile=$SCRATCH_MNT/$seq.swapfile
> > +make_unaligned_swapfile $swapfile
> > +$here/src/swapon $swapfile
> > +swapoff $swapfile
> > +
> > +echo "Silence is golden"
> > +# success, all done
> > +status=0
> > +exit
> > diff --git a/tests/generic/639.out b/tests/generic/639.out
> > new file mode 100644
> > index 00000000..62c66537
> > --- /dev/null
> > +++ b/tests/generic/639.out
> > @@ -0,0 +1,2 @@
> > +QA output created by 639
> > +Silence is golden
> > diff --git a/tests/generic/group b/tests/generic/group
> > index 9a636b23..48ffa3c7 100644
> > --- a/tests/generic/group
> > +++ b/tests/generic/group
> > @@ -641,3 +641,4 @@
> >  636 auto quick swap
> >  637 auto quick dir
> >  638 auto quick rw
> > +639 auto quick swap
> > --
> > 2.31.1
> >
>