Re: [PATCH v2] generic/391: check inode metadata on f{data}sync after power-cut

[Jaegeuk Kim <jaegeuk@kernel.org>]

On Fri, Nov 18, 2016 at 02:39:43PM +0800, Eryu Guan wrote:
> On Thu, Nov 17, 2016 at 11:20:51AM -0800, Jaegeuk Kim wrote:
> > This patch adds tests/generic/391 to test fsync and fdatasync with power-cuts.
> > 
> > The rule to check is:
> > 1) fsync should guarantee all the inode metadata after power-cut,
> > 2) fdatasync should guarantee i_size and i_blocks at least after power-cut.
> > 
> > Suggested-by: Chao Yu <yuchao0@huawei.com>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> >  tests/generic/391     | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/391.out |  11 ++++
> >  tests/generic/group   |   1 +
> >  3 files changed, 148 insertions(+)
> >  create mode 100644 tests/generic/391
> >  create mode 100644 tests/generic/391.out
> > 
> > diff --git a/tests/generic/391 b/tests/generic/391
> > new file mode 100644
> > index 0000000..2b95151
> > --- /dev/null
> > +++ b/tests/generic/391
> > @@ -0,0 +1,136 @@
> > +#! /bin/bash
> > +# FS QA Test 391
> > +#
> > +# Test inode's metadata after fsync or fdatasync calls.
> > +# In the case of fsync, filesystem should recover all the inode metadata, while
> > +# recovering i_blocks and i_size at least for fdatasync.
> > +#
> > +#-----------------------------------------------------------------------
> > +# Copyright (c) 2016 Jaegeuk Kim.  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
> > +. ./common/punch
> > +
> > +# real QA test starts here
> > +_supported_fs generic
> > +_supported_os Linux
> > +
> > +rm -f $seqres.full
> > +_require_scratch
> > +_require_scratch_shutdown
> > +_require_xfs_io_command "fpunch"
> > +
> > +_scratch_mkfs >/dev/null 2>&1
> > +_scratch_mount
> > +
> > +testfile=$SCRATCH_MNT/testfile
> > +
> > +# check inode metadata after shutdown
> > +check_inode_metadata()
> > +{
> > +	$XFS_IO_PROG -r -c "stat -v" $1 >$tmp.before
> > +	src/godown $SCRATCH_MNT >> $seqres.full
> > +	_scratch_cycle_mount
> > +	$XFS_IO_PROG -r -c "stat -v" $1 >$tmp.after
> > +
> > +	if [ $FSTYP = xfs ]; then
> > +		sed -i '/stat.blocks/d' $tmp.before
> > +		sed -i '/stat.blocks/d' $tmp.after
> > +	fi
> 
> Blacklist some fs "randomly" seems not easy to maintain, at least we
> need some comments to explain why we do this.
> 
> I prefer the other way Brian suggested, i.e. truncate the file to
> correct size before the real fsync/fdatasync to remove any preallocated
> blocks past eof. I made the following update and test passed on XFS
> without problems, what do you think?

I don't think that is a right way, since it breaks the existing IO behavior.
I tested a little bit, and it seems the key is to call fclose to truncate
out-of-eof blocks. Indeed, I could get the expected i_blocks by adding open and
close after shutdown->remount; please check v3.

BTW, does it make sense user needs to do fclose after power-cut to reclaim such
the preallocated blocks? I feel that XFS must reclaim them during recovery on
mount.

Thanks,

> 
> --- a/tests/generic/391
> +++ b/tests/generic/391
> @@ -65,10 +65,6 @@ check_inode_metadata()
>         _scratch_cycle_mount
>         $XFS_IO_PROG -r -c "stat -v" $1 >$tmp.after
>  
> -       if [ $FSTYP = xfs ]; then
> -               sed -i '/stat.blocks/d' $tmp.before
> -               sed -i '/stat.blocks/d' $tmp.after
> -       fi
>         diff $tmp.before $tmp.after >$tmp.diff
>  
>         if [ "$2" = "fdatasync" ]; then
> @@ -82,13 +78,19 @@ check_inode_metadata()
>  }
>  
>  # append XX KB with f{data}sync, followed by power-cut
> +# truncate file to the current size to avoid post-eof preallocated
> +# blocks on XFS
>  test_i_size()
>  {
> +       local len=$2
> +       local base_len=$((4 * 1024 * 1024))
> +       local new_len=$((base_len + len))
>         echo "==== i_size $2 test with $1 ====" | tee -a $seqres.full
> -       $XFS_IO_PROG -f -c "pwrite 0 4M"        \
> -                       -c "fsync"              \
> -                       -c "pwrite 4M $2"       \
> -                       -c "$1"                 \
> +       $XFS_IO_PROG -f -c "pwrite 0 $base_len"         \
> +                       -c "fsync"                      \
> +                       -c "pwrite $base_len $len"      \
> +                       -c "truncate $new_len"          \
> +                       -c "$1"                         \
>                         $testfile >/dev/null
>         check_inode_metadata $testfile $1
>  }
> @@ -108,12 +110,15 @@ test_i_time()
>  }
>  
>  # punch XX KB with f{data}sync, followed by power-cut
> +# truncate file to the current size to avoid post-eof preallocated
> +# blocks on XFS
>  test_punch()
>  {
>         echo "==== fpunch $2 test with $1 ====" | tee -a $seqres.full
>         $XFS_IO_PROG -f -c "pwrite 0 4202496"   \
>                         -c "fsync"              \
> -                       -c "fpunch 4194304 $2"\
> +                       -c "fpunch 4194304 $2"  \
> +                       -c "truncate 4202496"   \
>                         -c "$1"                 \
>                         $testfile >/dev/null
>  
> Thanks,
> Eryu