Re: [PATCH] generic: add gc stress test

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Apr 16, 2024 at 09:07:43AM +0000, Hans Holmberg wrote:
> +Zorro (doh!)
> 
> On 2024-04-15 13:23, Hans Holmberg wrote:
> > This test stresses garbage collection for file systems by first filling
> > up a scratch mount to a specific usage point with files of random size,
> > then doing overwrites in parallel with deletes to fragment the backing
> > storage, forcing reclaim.
> > 
> > Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
> > ---
> > 
> > Test results in my setup (kernel 6.8.0-rc4+)
> > 	f2fs on zoned nullblk: pass (77s)
> > 	f2fs on conventional nvme ssd: pass (13s)
> > 	btrfs on zoned nublk: fails (-ENOSPC)
> > 	btrfs on conventional nvme ssd: fails (-ENOSPC)
> > 	xfs on conventional nvme ssd: pass (8s)
> > 
> > Johannes(cc) is working on the btrfs ENOSPC issue.
> > 	
> >   tests/generic/744     | 124 ++++++++++++++++++++++++++++++++++++++++++
> >   tests/generic/744.out |   6 ++
> >   2 files changed, 130 insertions(+)
> >   create mode 100755 tests/generic/744
> >   create mode 100644 tests/generic/744.out
> > 
> > diff --git a/tests/generic/744 b/tests/generic/744
> > new file mode 100755
> > index 000000000000..2c7ab76bf8b1
> > --- /dev/null
> > +++ b/tests/generic/744
> > @@ -0,0 +1,124 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2024 Western Digital Corporation.  All Rights Reserved.
> > +#
> > +# FS QA Test No. 744
> > +#
> > +# Inspired by btrfs/273 and generic/015
> > +#
> > +# This test stresses garbage collection in file systems
> > +# by first filling up a scratch mount to a specific usage point with
> > +# files of random size, then doing overwrites in parallel with
> > +# deletes to fragment the backing zones, forcing reclaim.
> > +
> > +. ./common/preamble
> > +_begin_fstest auto
> > +
> > +# real QA test starts here
> > +
> > +_require_scratch
> > +
> > +# This test requires specific data space usage, skip if we have compression
> > +# enabled.
> > +_require_no_compress
> > +
> > +M=$((1024 * 1024))
> > +min_fsz=$((1 * ${M}))
> > +max_fsz=$((256 * ${M}))
> > +bs=${M}
> > +fill_percent=95
> > +overwrite_percentage=20
> > +seq=0
> > +
> > +_create_file() {
> > +	local file_name=${SCRATCH_MNT}/data_$1
> > +	local file_sz=$2
> > +	local dd_extra=$3
> > +
> > +	POSIXLY_CORRECT=yes dd if=/dev/zero of=${file_name} \
> > +		bs=${bs} count=$(( $file_sz / ${bs} )) \
> > +		status=none $dd_extra  2>&1
> > +
> > +	status=$?
> > +	if [ $status -ne 0 ]; then
> > +		echo "Failed writing $file_name" >>$seqres.full
> > +		exit
> > +	fi
> > +}

I wonder, is there a particular reason for doing all these file
operations with shell code instead of using fsstress to create and
delete files to fill the fs and stress all the zone-gc code?  This test
reminds me a lot of generic/476 but with more fork()ing.

--D

> > +
> > +_total_M() {
> > +	local total=$(stat -f -c '%b' ${SCRATCH_MNT})
> > +	local bs=$(stat -f -c '%S' ${SCRATCH_MNT})
> > +	echo $(( ${total} * ${bs} / ${M}))
> > +}
> > +
> > +_used_percent() {
> > +	local available=$(stat -f -c '%a' ${SCRATCH_MNT})
> > +	local total=$(stat -f -c '%b' ${SCRATCH_MNT})
> > +	echo $((100 - (100 * ${available}) / ${total} ))
> > +}
> > +
> > +
> > +_delete_random_file() {
> > +	local to_delete=$(find ${SCRATCH_MNT} -type f | shuf | head -1)
> > +	rm $to_delete
> > +	sync ${SCRATCH_MNT}
> > +}
> > +
> > +_get_random_fsz() {
> > +	local r=$RANDOM
> > +	echo $(( ${min_fsz} + (${max_fsz} - ${min_fsz}) * (${r} % 100) / 100 ))
> > +}
> > +
> > +_direct_fillup () {
> > +	while [ $(_used_percent) -lt $fill_percent ]; do
> > +		local fsz=$(_get_random_fsz)
> > +
> > +		_create_file $seq $fsz "oflag=direct conv=fsync"
> > +		seq=$((${seq} + 1))
> > +	done
> > +}
> > +
> > +_mixed_write_delete() {
> > +	local dd_extra=$1
> > +	local total_M=$(_total_M)
> > +	local to_write_M=$(( ${overwrite_percentage} * ${total_M} / 100 ))
> > +	local written_M=0
> > +
> > +	while [ $written_M -lt $to_write_M ]; do
> > +		if [ $(_used_percent) -lt $fill_percent ]; then
> > +			local fsz=$(_get_random_fsz)
> > +
> > +			_create_file $seq $fsz "$dd_extra"
> > +			written_M=$((${written_M} + ${fsz}/${M}))
> > +			seq=$((${seq} + 1))
> > +		else
> > +			_delete_random_file
> > +		fi
> > +	done
> > +}
> > +
> > +seed=$RANDOM
> > +RANDOM=$seed
> > +echo "Running test with seed=$seed" >>$seqres.full
> > +
> > +_scratch_mkfs_sized $((8 * 1024 * 1024 * 1024)) >>$seqres.full
> > +_scratch_mount
> > +
> > +echo "Starting fillup using direct IO"
> > +_direct_fillup
> > +
> > +echo "Starting mixed write/delete test using direct IO"
> > +_mixed_write_delete "oflag=direct"
> > +
> > +echo "Starting mixed write/delete test using buffered IO"
> > +_mixed_write_delete ""
> > +
> > +echo "Syncing"
> > +sync ${SCRATCH_MNT}/*
> > +
> > +echo "Done, all good"
> > +
> > +# success, all done
> > +status=0
> > +exit
> > diff --git a/tests/generic/744.out b/tests/generic/744.out
> > new file mode 100644
> > index 000000000000..b40c2f43108e
> > --- /dev/null
> > +++ b/tests/generic/744.out
> > @@ -0,0 +1,6 @@
> > +QA output created by 744
> > +Starting fillup using direct IO
> > +Starting mixed write/delete test using direct IO
> > +Starting mixed write/delete test using buffered IO
> > +Syncing
> > +Done, all good
>