Date:   Wed, 14 Jun 2017 07:55:17 -0400
From:   Jeff Layton <jlayton@...hat.com>
To:     Eryu Guan <eguan@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>,
        tytso@....edu, axboe@...nel.dk, mawilcox@...rosoft.com,
        ross.zwisler@...ux.intel.com, corbet@....net,
        Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
        David Sterba <dsterba@...e.com>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        David Howells <dhowells@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [xfstests PATCH v4 5/5] btrfs: make a btrfs version of
 writeback error reporting test

On Tue, 2017-06-13 at 16:40 +0800, Eryu Guan wrote:
> On Mon, Jun 12, 2017 at 08:42:13AM -0400, Jeff Layton wrote:
> > Make a new btrfs/999 test that works the way Chris Mason suggested:
> > 
> > Build a filesystem with 2 devices that stripes the data across
> > both devices, but mirrors metadata across both. Then, make one
> > of the devices fail and see how fsync is handled.
> > 
> > Signed-off-by: Jeff Layton <jlayton@...hat.com>
> > ---
> >  tests/btrfs/999   | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 
> Missing btrfs/999.out file
> 
> >  tests/btrfs/group |  1 +
> >  2 files changed, 94 insertions(+)
> >  create mode 100755 tests/btrfs/999
> > 
> > diff --git a/tests/btrfs/999 b/tests/btrfs/999
> > new file mode 100755
> > index 000000000000..84031cc0d913
> > --- /dev/null
> > +++ b/tests/btrfs/999
> > @@ -0,0 +1,93 @@
> > +#! /bin/bash
> > +# FS QA Test No. 999
> > +#
> > +# Open a file several times, write to it, fsync on all fds and make sure that
> > +# they all return 0. Change the device to start throwing errors. Write again
> > +# on all fds and fsync on all fds. Ensure that we get errors on all of them.
> > +# Then fsync on all one last time and verify that all return 0.
> > +#
> > +#-----------------------------------------------------------------------
> > +# Copyright (c) 2017, Jeff Layton <jlayton@...hat.com>
> > +#
> > +# 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 -rf $tmp.* $testdir
> > +    _dmerror_cleanup
> > +}
> > +
> > +# get standard environment, filters and checks
> > +. ./common/rc
> > +. ./common/filter
> > +. ./common/dmerror
> > +
> > +# real QA test starts here
> > +_supported_os Linux
> > +_require_dm_target error
> > +_require_test_program fsync-err
> > +_require_test_program dmerror
> > +
> > +# bring up dmerror device
> > +_scratch_unmount
> > +_dmerror_init
> > +
> > +# Replace first device with error-test device
> > +old_SCRATCH_DEV=$SCRATCH_DEV
> > +SCRATCH_DEV_POOL=`echo $SCRATCH_DEV_POOL | perl -pe "s#$SCRATCH_DEV#$DMERROR_DEV#"`
> > +SCRATCH_DEV=$DMERROR_DEV
> > +
> > +_require_scratch
> > +_require_scratch_dev_pool
> 
> Need "_require_scratch_dev_pool_equal_size" too, since test creates
> raid1 profile for metadata.
> 
> Thanks,
> Eryu
> 

Is this really needed?

I've been running this test on btrfs with devices that are not of equal
size, and it seems to work just fine. The test doesn't write a lot of
data (just a few megs at most), so I don't think we'll run out of space
unless you have some really small devices in there.

> > +
> > +rm -f $seqres.full
> > +
> > +echo "Format and mount"
> > +
> > +_scratch_pool_mkfs "-d raid0 -m raid1" > $seqres.full 2>&1
> > +_scratch_mount
> > +
> > +# How much do we need to write? We need to hit all of the stripes. btrfs uses
> > +# a fixed 64k stripesize, so write enough to hit each one
> > +number_of_devices=`echo $SCRATCH_DEV_POOL | wc -w`
> > +write_kb=$(($number_of_devices * 64))
> > +_require_fs_space $SCRATCH_MNT $write_kb
> > +
> > +testfile=$SCRATCH_MNT/fsync-err-test
> > +
> > +SCRATCH_DEV=$old_SCRATCH_DEV
> > +$here/src/fsync-err -b $(($write_kb * 1024)) -d $here/src/dmerror $testfile
> > +
> > +# success, all done
> > +_dmerror_load_working_table
> > +
> > +# fs may be corrupt after this -- attempt to repair it
> > +_repair_scratch_fs >> $seqres.full
> > +
> > +# remove dmerror device
> > +_dmerror_cleanup
> > +
> > +status=0
> > +exit
> > diff --git a/tests/btrfs/group b/tests/btrfs/group
> > index 6f19619e877c..8dbdfbfe29fd 100644
> > --- a/tests/btrfs/group
> > +++ b/tests/btrfs/group
> > @@ -145,3 +145,4 @@
> >  141 auto quick
> >  142 auto quick
> >  143 auto quick
> > +999 auto quick
> > -- 
> > 2.13.0
> > 

-- 
Jeff Layton <jlayton@...hat.com>

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