Re: [PATCH] xfstests: add test for ext4 fallocate collapse range check

["Lukáš Czerner" <lczerner@redhat.com>]

On Thu, 19 Jun 2014, Xing Gu wrote:

> Date: Thu, 19 Jun 2014 13:50:04 +0800
> From: Xing Gu <gux.fnst@cn.fujitsu.com>
> To: fstests@vger.kernel.org
> Cc: Xing Gu <gux.fnst@cn.fujitsu.com>
> Subject: [PATCH] xfstests: add test for ext4 fallocate collapse range check
> 
> This is a test to verify the procedure which checks whether
> offset + len is bigger than i_size is removed from do_fallocate
> in collapse range to the file system, and ensure that i_size is
> not going to change.
> 
> Signed-off-by: Xing Gu <gux.fnst@cn.fujitsu.com>
> ---
>  tests/ext4/307     | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/ext4/307.out |  1 +
>  tests/ext4/group   |  1 +
>  3 files changed, 82 insertions(+)
>  create mode 100755 tests/ext4/307
>  create mode 100644 tests/ext4/307.out
> 
> diff --git a/tests/ext4/307 b/tests/ext4/307
> new file mode 100755
> index 0000000..595c7c1
> --- /dev/null
> +++ b/tests/ext4/307
> @@ -0,0 +1,80 @@
> +#! /bin/bash
> +# FS QA Test No. 307
> +#
> +# Regression test for commit:
> +# 23fffa9 fs: move falloc collapse range check into the filesystem methods

The check is the same but it's in a different place. Also why is this
ext4 specific ? Also you're testing a race, not this commit .. see
below.

> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2014 Fujitsu.  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"
> +
> +PIDS=""
> +status=1	# failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> +	kill $PIDS >/dev/null 2>&1
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# real QA test starts here
> +_supported_fs ext4
> +_supported_os Linux
> +_require_scratch
> +_require_xfs_io_command "fcollapse"
> +
> +_scratch_mkfs > $seqres.full 2>&1
> +_scratch_mount
> +
> +old_bug=`dmesg | grep -c "kernel BUG"`
> +
> +testfile=$SCRATCH_MNT/file.$seq
> +# fcollapse/truncate continuously and simultaneously
> +# a same file
> +for ((i=1; i <= 100; i++))
> +do
> +	while true;do
> +		$XFS_IO_PROG -f -c 'truncate 100k' $testfile 2>> $seqres.full
> +		$XFS_IO_PROG -f -c 'fcollapse 0 16k' $testfile 2>> $seqres.full
> +	done &
> +	PIDS="$PIDS $!"
> +	while true;do
> +		$XFS_IO_PROG -f -c 'truncate 0' $testfile 2>> $seqres.full
> +	done &
> +	PIDS="$PIDS $!"

It does not look like it's just checking whether we correctly bail
out if collapse range ends past i_size, but rather it's checking for
the truncate/collapse range race.

Also in description you're saying that we need to make sure that
i_size is not going to change, which is not tested here at all.

So I think that you need to split it in two tests:

 - test truncate/collapse range race (what is the failure
   condition?)
 - test whether we correctly bail out when collapse range is past
   i_size and make sure that i_size did not change at all.

Thanks!
-Lukas

> +done
> +# sleep for 180s, BUG_ON is triggered within 3 minutes
> +# in most case
> +sleep 180
> +
> +new_bug=`dmesg | grep -c "kernel BUG"`
> +if [ $new_bug -ne $old_bug ]; then
> +	echo "kernel bug detected, check dmesg for more infomation."
> +fi
> +
> +kill $PIDS >/dev/null 2>&1
> +wait
> +status=0
> +exit
> diff --git a/tests/ext4/307.out b/tests/ext4/307.out
> new file mode 100644
> index 0000000..260c17c
> --- /dev/null
> +++ b/tests/ext4/307.out
> @@ -0,0 +1 @@
> +QA output created by 307
> diff --git a/tests/ext4/group b/tests/ext4/group
> index 7e66035..0f1852f 100644
> --- a/tests/ext4/group
> +++ b/tests/ext4/group
> @@ -12,3 +12,4 @@
>  304 aio dangerous ioctl rw stress
>  305 auto
>  306 auto rw resize quick
> +307 auto
>