Re: [PATCH 2/2] fstests: btrfs: dm-logwrites test for fstrim and fsstress workload

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2019/10/22 下午5:09, Amir Goldstein wrote:
> On Tue, Oct 22, 2019 at 11:00 AM Qu Wenruo <wqu@suse.com> wrote:
>>
>> There is a fs corruption report of a tree block in use get trimmed, and
>> cause fs corruption.
>>
>> Although I haven't found the cause from the source code, it won't hurt
>> to add such test case.
>>
>> The test case is limited to btrfs due to the replay-log --check|--fsck
>> hack to reduce runtime.
> 
> I am not sure why this is referred to as a hack?
> 
>> Other fs can't go with the replay-log --check|--fsck hack as their fsck
>> will report dirty journal as error.
> 
> This doesn't make the test btrfs specific.
> The helper you use log_writes_fast_replay_check() is already dupliacte
> code from btrfs/192 and it should be in common/dmlogwrites.
> The helper itself would be quite generic if it didn't hardcode btrfs check
> tool.

> 
> I think a better solution would be to _require_fast_check_fs and it is
> possible that other fs will have a future flag for fsck to not fail if
> journal needs to be replayed, but the check whatever is possible to check
> in that state (e.g. the super block and the consistency of the journal).

That's the best case, but we're not yet at the stage, so I'll keep the
test in btrfs group for now.

> 
> However, regarding requiring no_holes, I am not sure how you would
> encode that in a generic test???

That can be kinda worked around, as btrfs is soon to default to no-holes
feature.

But for now, the explicit no-holes mkfs option is still needed.

Thanks,
Qu

> 
> Thanks,
> Amir.
> 
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>> ---
>> Due to recent change in btrfs side, already trimmed tree blocks won't
>> get trimmed again until new data is written.
>>
>> This makes things safer, and I'm not sure if it's the reason why the
>> test never fails on latest kernel.
>> ---
>>  tests/btrfs/197     | 131 ++++++++++++++++++++++++++++++++++++++++++++
>>  tests/btrfs/197.out |   2 +
>>  tests/btrfs/group   |   1 +
>>  3 files changed, 134 insertions(+)
>>  create mode 100755 tests/btrfs/197
>>  create mode 100644 tests/btrfs/197.out
>>
>> diff --git a/tests/btrfs/197 b/tests/btrfs/197
>> new file mode 100755
>> index 00000000..c86af7b6
>> --- /dev/null
>> +++ b/tests/btrfs/197
>> @@ -0,0 +1,131 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (C) 2019 SUSE Linux Products GmbH. All Rights Reserved.
>> +
>> +# FS QA Test 197
>> +#
>> +# Test btrfs consistency after each DISCARD for a workload with fstrim and
>> +# fsstress.
>> +#
>> +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 /
>> +       kill -q $fstrim_pid &> /dev/null
>> +       "$KILLALL_PROG" -q $FSSTRESS_PROG &> /dev/null
>> +       wait
>> +       _log_writes_cleanup &> /dev/null
>> +       rm -f $tmp.*
>> +}
>> +
>> +# get standard environment, filters and checks
>> +. ./common/rc
>> +. ./common/filter
>> +. ./common/dmlogwrites
>> +
>> +# remove previous $seqres.full before test
>> +rm -f $seqres.full
>> +
>> +# real QA test starts here
>> +
>> +# Modify as appropriate.
>> +_supported_fs btrfs
>> +_supported_os Linux
>> +_require_command "$KILLALL_PROG" killall
>> +_require_command "$BLKDISCARD_PROG" blkdiscard
>> +_require_btrfs_fs_feature "no_holes"
>> +_require_btrfs_mkfs_feature "no-holes"
>> +_require_fstrim
>> +_require_log_writes
>> +_require_scratch
>> +
>> +runtime=30
>> +nr_cpus=$("$here/src/feature" -o)
>> +# cap nr_cpus to 8 to avoid spending too much time on hosts with many cpus
>> +if [ $nr_cpus -gt 8 ]; then
>> +       nr_cpus=8
>> +fi
>> +fsstress_args=$(_scale_fsstress_args -w -d $SCRATCH_MNT -n 99999 -p $nr_cpus \
>> +               $FSSTRESS_AVOID)
>> +
>> +fstrim_workload()
>> +{
>> +       trap "wait; exit" SIGTERM
>> +
>> +       while  true; do
>> +               $FSTRIM_PROG -v $SCRATCH_MNT >> $seqres.full
>> +       done
>> +}
>> +
>> +# Replay and check each fua/flush (specified by $2) point.
>> +#
>> +# Since dm-log-writes records bio sequentially, even just replaying a range
>> +# still needs to iterate all records before the end point.
>> +# When number of records grows, it will be unacceptably slow, thus we need
>> +# to use relay-log itself to trigger fsck, avoid unnecessary seek.
>> +log_writes_fast_replay_check()
>> +{
>> +       local check_point=$1
>> +       local blkdev=$2
>> +       local fsck_command="$BTRFS_UTIL_PROG check $blkdev"
>> +       local ret
>> +
>> +       [ -z "$check_point" -o -z "$blkdev" ] && _fail \
>> +       "check_point and blkdev must be specified for log_writes_fast_replay_check"
>> +
>> +       # Replay to first mark
>> +       $here/src/log-writes/replay-log --log $LOGWRITES_DEV \
>> +               --replay $blkdev --end-mark prepare
>> +       $here/src/log-writes/replay-log --log $LOGWRITES_DEV \
>> +               --replay $blkdev --start-mark prepare \
>> +               --check $check_point --fsck "$fsck_command" \
>> +               &> $tmp.full_fsck
>> +       ret=$?
>> +       tail -n 150 $tmp.full_fsck > $seqres.full
>> +       [ $ret -ne 0 ] && _fail "fsck failed during replay"
>> +}
>> +
>> +_log_writes_init $SCRATCH_DEV
>> +
>> +# Discard the whole devices so when some tree pointer is wrong, it won't point
>> +# to some older valid tree blocks, so we can detect it.
>> +$BLKDISCARD_PROG $LOGWRITES_DMDEV > /dev/null 2>&1
>> +
>> +# The regular workaround to avoid false alert on unexpected holes
>> +_log_writes_mkfs -O no-holes >> $seqres.full
>> +_log_writes_mount
>> +
>> +$FSTRIM_PROG -v $SCRATCH_MNT >> $seqres.full || _notrun "FSTRIM not supported"
>> +
>> +_log_writes_mark prepare
>> +
>> +fstrim_workload &
>> +fstrim_pid=$!
>> +
>> +"$FSSTRESS_PROG" $fsstress_args > /dev/null &
>> +sleep $runtime
>> +
>> +"$KILLALL_PROG" -q "$FSSTRESS_PROG" &> /dev/null
>> +kill $fstrim_pid
>> +wait
>> +
>> +_log_writes_unmount
>> +_log_writes_remove
>> +
>> +# The best checkpoint is discard, however since there are a lot of
>> +# discard, using discard check point is too time consuming.
>> +# Here trade coverage for a much shorter runtime
>> +log_writes_fast_replay_check flush "$SCRATCH_DEV"
>> +
>> +echo "Silence is golden"
>> +# success, all done
>> +status=0
>> +exit
>> diff --git a/tests/btrfs/197.out b/tests/btrfs/197.out
>> new file mode 100644
>> index 00000000..3bbd3143
>> --- /dev/null
>> +++ b/tests/btrfs/197.out
>> @@ -0,0 +1,2 @@
>> +QA output created by 197
>> +Silence is golden
>> diff --git a/tests/btrfs/group b/tests/btrfs/group
>> index c2ab3e7d..ee35fa59 100644
>> --- a/tests/btrfs/group
>> +++ b/tests/btrfs/group
>> @@ -199,3 +199,4 @@
>>  194 auto volume
>>  195 auto volume
>>  196 auto metadata log volume
>> +197 auto replay trim
>> --
>> 2.23.0
>>


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