Re: [PATCH v3 4/4] generic: test fs freeze/unfreeze and mount/umount race

[Brian Foster <bfoster@redhat.com>]

On Fri, Apr 03, 2015 at 03:18:34PM +0800, Eryu Guan wrote:
> Exercise fs freeze/unfreeze and mount/umount race, which could lead to
> use-after-free oops.
> 
> This commit fixed the issue:
> 1494583 fix get_active_super()/umount() race
> 
> This test case is based on a script from Monakhov Dmitriy.
> 
> Signed-off-by: Eryu Guan <eguan@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> v3:
> - rebase and re-numbered to generic/085
> - add more comments to explain why results of suspend/resume, mount/umount are ignored
> 
> v2:
> - add comments to explain dmsetup is used not xfs_freeze to freeze filesystem
> - detect failures in setup phase, so test exits not continus with errors
> 
>  tests/generic/085     | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/085.out |   2 +
>  tests/generic/group   |   1 +
>  3 files changed, 109 insertions(+)
>  create mode 100755 tests/generic/085
>  create mode 100644 tests/generic/085.out
> 
> diff --git a/tests/generic/085 b/tests/generic/085
> new file mode 100755
> index 0000000..8398752
> --- /dev/null
> +++ b/tests/generic/085
> @@ -0,0 +1,106 @@
> +#! /bin/bash
> +# FS QA Test No. 085
> +#
> +# Exercise fs freeze/unfreeze and mount/umount race, which could lead to
> +# use-after-free oops.
> +#
> +# This commit fixed the issue:
> +# 1494583 fix get_active_super()/umount() race
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2015 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.*
> +	cleanup_dmdev
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# real QA test starts here
> +_supported_fs generic
> +_supported_os Linux
> +_require_scratch
> +_require_block_device $SCRATCH_DEV
> +_require_command $DMSETUP_PROG
> +_require_freeze
> +
> +setup_dmdev()
> +{
> +	table="0 $size_in_sector linear $SCRATCH_DEV 0"
> +	$DMSETUP_PROG create $node --table "$table" >>$seqres.full 2>&1 && \
> +	$DMSETUP_PROG mknodes >/dev/null 2>&1
> +	return $?
> +}
> +
> +cleanup_dmdev()
> +{
> +	# in case it's still suspended and/or mounted
> +	$DMSETUP_PROG resume $lvdev >/dev/null 2>&1
> +	$UMOUNT_PROG $lvdev >/dev/null 2>&1
> +
> +	$DMSETUP_PROG remove $node >>$seqres.full 2>&1
> +	$DMSETUP_PROG mknodes >/dev/null 2>&1
> +}
> +
> +rm -f $seqres.full
> +echo "Silence is golden"
> +
> +size=$((256 * 1024 * 1024))
> +size_in_sector=$((size / 512))
> +_scratch_mkfs_sized $size >>$seqres.full 2>&1
> +
> +node=$seq-test
> +lvdev=/dev/mapper/$node
> +setup_dmdev || _fail "setup dm device failed"
> +
> +# take use of dmsetup suspend to freeze the fs.
> +# xfs_freeze/fsfreeze cannot be used in this test, because it can possibly
> +# freeze the root fs of the host when SCRATCH_MNT is not mounted
> +#
> +# And the results of the racing commands (suspend/resume, mount/umount) are not
> +# important, as long as they're racing with each other. So just throw away the
> +# outputs and ignore the results.
> +for ((i=0; i<100; i++)); do
> +	$DMSETUP_PROG suspend $lvdev >/dev/null 2>&1
> +	$DMSETUP_PROG resume $lvdev >/dev/null 2>&1
> +done &
> +pid=$!
> +for ((i=0; i<100; i++)); do
> +	$MOUNT_PROG $lvdev $SCRATCH_MNT >/dev/null 2>&1
> +	$UMOUNT_PROG $lvdev >/dev/null 2>&1
> +done &
> +pid="$pid $!"
> +
> +wait $pid
> +
> +status=0
> +exit
> diff --git a/tests/generic/085.out b/tests/generic/085.out
> new file mode 100644
> index 0000000..76aef1a
> --- /dev/null
> +++ b/tests/generic/085.out
> @@ -0,0 +1,2 @@
> +QA output created by 085
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index 5cbc1fe..a96b901 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -87,6 +87,7 @@
>  082 auto quick
>  083 rw auto enospc stress
>  084 auto metadata quick
> +085 auto freeze mount
>  088 perms auto quick
>  089 metadata auto
>  091 rw auto quick
> -- 
> 1.8.3.1
> 
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