Re: [PATCH v4 3/3] xfs: stress test for shrinking free space in the last AG

From: Gao Xiang <hsiangkao@redhat.com>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-xfs@vger.kernel.org, fstests@vger.kernel.org,
	Zorro Lang <zlang@redhat.com>, Eryu Guan <guan@eryu.me>
Subject: Re: [PATCH v4 3/3] xfs: stress test for shrinking free space in the last AG
Date: Tue, 11 May 2021 10:19:27 +0800	[thread overview]
Message-ID: <20210511021927.GE741809@xiangao.remote.csb> (raw)
In-Reply-To: <20210510180836.GC8558@magnolia>

On Mon, May 10, 2021 at 11:08:36AM -0700, Darrick J. Wong wrote:
> On Fri, Apr 02, 2021 at 05:49:37PM +0800, Gao Xiang wrote:
> > This adds a stress testcase to shrink free space as much as
> > possible in the last AG with background fsstress workload.
> > 
> > The expectation is that no crash happens with expected output.
> > 
> > Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
> > ---
> >  tests/xfs/991     | 118 ++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/xfs/991.out |   8 ++++
> >  tests/xfs/group   |   1 +
> >  3 files changed, 127 insertions(+)
> >  create mode 100755 tests/xfs/991
> >  create mode 100644 tests/xfs/991.out
> > 
> > diff --git a/tests/xfs/991 b/tests/xfs/991
> > new file mode 100755
> > index 00000000..8ad0b8c7
> > --- /dev/null
> > +++ b/tests/xfs/991
> > @@ -0,0 +1,118 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2020-2021 Red Hat, Inc.  All Rights Reserved.
> > +#
> > +# FS QA Test 991
> > +#
> > +# XFS online shrinkfs stress test
> > +#
> > +# This test attempts to shrink unused space as much as possible with
> > +# background fsstress workload. It will decrease the shrink size if
> > +# larger size fails. And totally repeat 2 * TIME_FACTOR times.
> > +#
> > +seq=`basename $0`
> > +seqres=$RESULT_DIR/$seq
> > +echo "QA output created by $seq"
> > +
> > +here=`pwd`
> > +tmp=/tmp/$$
> > +status=1	# failure is the default!
> > +trap "rm -f $tmp.*; exit \$status" 0 1 2 3 15
> > +
> > +# get standard environment, filters and checks
> > +. ./common/rc
> > +. ./common/filter
> > +
> > +create_scratch()
> > +{
> > +	_scratch_mkfs_xfs $@ | tee -a $seqres.full | \
> > +		_filter_mkfs 2>$tmp.mkfs >/dev/null
> > +	. $tmp.mkfs
> > +
> > +	_scratch_mount
> > +	# fix the reserve block pool to a known size so that the enospc
> > +	# calculations work out correctly.
> > +	_scratch_resvblks 1024 > /dev/null 2>&1
> > +}
> > +
> > +fill_scratch()
> > +{
> > +	$XFS_IO_PROG -f -c "falloc 0 $1" $SCRATCH_MNT/resvfile
> > +}
> > +
> > +stress_scratch()
> > +{
> > +	local procs=3
> > +	local nops=$((1000 * LOAD_FACTOR))
> 
> Um... _scale_fsstress_args already scales the -p and -n arguments, why
> is it necessary to scale nops by time /and/ load?

Yeah, I forgot to check what _scale_fsstress_args's implemented.
Yes, it's unnecessary. will fix.

> 
> > +	# -w ensures that the only ops are ones which cause write I/O
> > +	local FSSTRESS_ARGS=`_scale_fsstress_args -d $SCRATCH_MNT -w \
> > +		-p $procs -n $nops $FSSTRESS_AVOID`
> > +	$FSSTRESS_PROG $FSSTRESS_ARGS >> $seqres.full 2>&1
> > +}
> > +
> > +# real QA test starts here
> > +_supported_fs xfs
> > +_require_xfs_scratch_shrink
> > +_require_xfs_io_command "falloc"
> > +
> > +rm -f $seqres.full
> > +_scratch_mkfs_xfs | tee -a $seqres.full | _filter_mkfs 2>$tmp.mkfs
> > +. $tmp.mkfs	# extract blocksize and data size for scratch device
> > +
> > +decsize=`expr  42 \* 1048576`	# shrink in chunks of this size at most
> 
> Might it be nice to inject a little bit of randomness here?

okay, will update.

> 
> > +endsize=`expr 125 \* 1048576`	# stop after shrinking this big
> > +[ `expr $endsize / $dbsize` -lt $dblocks ] || _notrun "Scratch device too small"
> > +
> > +nags=2
> > +totalcount=$((2 * TIME_FACTOR))
> > +
> > +while [ $totalcount -gt 0 ]; do
> > +	size=`expr 1010 \* 1048576`	# 1010 megabytes initially
> > +	logblks=$(_scratch_find_xfs_min_logblocks -dsize=${size} -dagcount=${nags})
> 
> (Does all this logic still work if an external log device is present?)

I didn't check the external log device case, but it seems
_scratch_find_xfs_min_logblocks was used in many cases before?
(e.g. xfs/104, how such cases work with an external log device?)

> 
> > +
> > +	create_scratch -lsize=${logblks}b -dsize=${size} -dagcount=${nags}
> > +
> > +	for i in `seq 125 -1 90`; do
> > +		fillsize=`expr $i \* 1048576`
> > +		out="$(fill_scratch $fillsize 2>&1)"
> > +		echo "$out" | grep -q 'No space left on device' && continue
> > +		test -n "${out}" && echo "$out"
> > +		break
> > +	done
> > +
> > +	while [ $size -gt $endsize ]; do
> > +		stress_scratch &
> > +		sleep 1
> > +
> > +		decb=`expr $decsize / $dbsize`    # in data blocks
> > +		while [ $decb -gt 0 ]; do
> > +			sizeb=`expr $size / $dbsize - $decb`
> > +
> > +			$XFS_GROWFS_PROG -D ${sizeb} $SCRATCH_MNT \
> > +				>> $seqres.full 2>&1 && break
> > +
> > +			[ $decb -gt 100 ] && decb=`expr $decb + $RANDOM % 10`
> > +			decb=`expr $decb / 2`
> > +		done
> > +
> > +		wait
> > +		[ $decb -eq 0 ] && break
> > +
> > +		# get latest dblocks
> > +		$XFS_INFO_PROG $SCRATCH_MNT 2>&1 | _filter_mkfs 2>$tmp.growfs >/dev/null
> > +		. $tmp.growfs
> > +
> > +		size=`expr $dblocks \* $dbsize`
> > +		_scratch_unmount
> > +		_repair_scratch_fs >> $seqres.full
> 
> Why isn't "_scratch_xfs_repair -n" here sufficient?

That sounds better if '-n' can detect all cases without '-n' (since I've
heard previously some buggy fsckxxx doesn't produce the same result with
or without '-n'...)

Will update.

> 
> > +		_scratch_mount
> > +	done
> > +
> > +	_scratch_unmount
> > +	_repair_scratch_fs >> $seqres.full
> 
> ...and here?

Will update too.

Thanks,
Gao Xiang

> 
> > +	totalcount=`expr $totalcount - 1`
> > +done
> > +
> > +echo "*** done"
> > +status=0
> > +exit
> > diff --git a/tests/xfs/991.out b/tests/xfs/991.out
> > new file mode 100644
> > index 00000000..e8209672
> > --- /dev/null
> > +++ b/tests/xfs/991.out
> > @@ -0,0 +1,8 @@
> > +QA output created by 991
> > +meta-data=DDEV isize=XXX agcount=N, agsize=XXX blks
> > +data     = bsize=XXX blocks=XXX, imaxpct=PCT
> > +         = sunit=XXX swidth=XXX, unwritten=X
> > +naming   =VERN bsize=XXX
> > +log      =LDEV bsize=XXX blocks=XXX
> > +realtime =RDEV extsz=XXX blocks=XXX, rtextents=XXX
> > +*** done
> > diff --git a/tests/xfs/group b/tests/xfs/group
> > index 472c8f9a..53e68bea 100644
> > --- a/tests/xfs/group
> > +++ b/tests/xfs/group
> > @@ -521,3 +521,4 @@
> >  538 auto stress
> >  539 auto quick mount
> >  990 auto quick growfs shrinkfs
> > +991 auto growfs shrinkfs ioctl prealloc stress
> > -- 
> > 2.27.0
> > 
> 