Re: [PATCH] fstests: btrfs: check qgroup doesn't crash when beyond limit

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

[-- Attachment #1.1: Type: text/plain, Size: 4358 bytes --]



On 2020/11/11 下午10:38, Filipe Manana wrote:
> On Wed, Nov 11, 2020 at 11:32 AM Qu Wenruo <wqu@suse.com> wrote:
>>
>> There is a bug that, when btrfs is beyond qgroup limit, touching a file
>> could crash btrfs.
>>
>> Such beyond limit situation needs to be intentionally created, e.g.
>> writing 1GiB file, then limit the subvolume to 512 MiB.
>> As current qgroup works pretty well at preventing us from reaching the
>> limit.
>>
>> This makes existing qgroup test cases unable to detect it.
>>
>> The regression is introduced by commit c53e9653605d ("btrfs: qgroup: try
>> to flush qgroup space when we get -EDQUOT"), and the fix is titled
>> "btrfs: qgroup: don't commit transaction when we have already
>>  hold a transaction handler"
>>
>> Link: https://bugzilla.suse.com/show_bug.cgi?id=1178634
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
> 
> Reviewed-by: Filipe Manana <fdmanana@suse.com>
> 
> Looks good, just one comment below.
> 
>> ---
>>  tests/btrfs/154     | 62 +++++++++++++++++++++++++++++++++++++++++++++
>>  tests/btrfs/154.out |  2 ++
>>  tests/btrfs/group   |  1 +
>>  3 files changed, 65 insertions(+)
>>  create mode 100755 tests/btrfs/154
>>  create mode 100644 tests/btrfs/154.out
>>
>> diff --git a/tests/btrfs/154 b/tests/btrfs/154
>> new file mode 100755
>> index 00000000..2a65d182
>> --- /dev/null
>> +++ b/tests/btrfs/154
>> @@ -0,0 +1,62 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (c) 2020 SUSE Linux Products GmbH. All Rights Reserved.
>> +#
>> +# FS QA Test 154
>> +#
>> +# Test if btrfs qgroup would crash if we're modifying the fs
>> +# after exceeding the limit
>> +#
>> +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
>> +
>> +# remove previous $seqres.full before test
>> +rm -f $seqres.full
>> +
>> +# real QA test starts here
>> +
>> +# Modify as appropriate.
>> +_supported_fs btrfs
>> +
>> +# Need at least 2GiB
>> +_require_scratch_size $((2 * 1024 * 1024))
>> +_scratch_mkfs > /dev/null 2>&1
>> +
>> +_scratch_mount
>> +
>> +_pwrite_byte 0xcd 0 1G $SCRATCH_MNT/file >> $seqres.full
>> +
>> +# Make sure the data reach disk so later qgroup scan can see it
>> +sync
>> +
>> +$BTRFS_UTIL_PROG quota enable $SCRATCH_MNT
>> +$BTRFS_UTIL_PROG quota rescan -w $SCRATCH_MNT >> $seqres.full
>> +
>> +# Set the limit to just 512MiB, which is way below the existing usage
>> +$BTRFS_UTIL_PROG qgroup limit  512M $SCRATCH_MNT $SCRATCH_MNT
> 
> $SCRATCH_MNT twice by mistake, though the command still works and the
> test still reproduces the issue.


Nope, that's the expected behavior.

Btrfs qgroup limit <size> <path>|<qgroupid> <path>

The first path is to determine qgroupid, while the last path is to
determine the fs.

In this particular case, since we're limit the 0/5 qgroup, it's also the
as the mount point, thus we specific it twice.

Thanks,
Qu
> 
> Eryu can probably remove one occurrence when picking this patch.
> 
> Thanks.
> 
>> +
>> +# Touch above file, if kernel not patched, it will trigger an ASSERT()
>> +#
>> +# Even for patched kernel, we will still get EDQUOT error, but that
>> +# is expected behavior.
>> +touch $SCRATCH_MNT/file 2>&1 | _filter_scratch
>> +
>> +# success, all done
>> +status=0
>> +exit
>> diff --git a/tests/btrfs/154.out b/tests/btrfs/154.out
>> new file mode 100644
>> index 00000000..b526c3f3
>> --- /dev/null
>> +++ b/tests/btrfs/154.out
>> @@ -0,0 +1,2 @@
>> +QA output created by 154
>> +touch: setting times of 'SCRATCH_MNT/file': Disk quota exceeded
>> diff --git a/tests/btrfs/group b/tests/btrfs/group
>> index d18450c7..c491e339 100644
>> --- a/tests/btrfs/group
>> +++ b/tests/btrfs/group
>> @@ -156,6 +156,7 @@
>>  151 auto quick volume
>>  152 auto quick metadata qgroup send
>>  153 auto quick qgroup limit
>> +154 auto quick qgroup limit
>>  155 auto quick send
>>  156 auto quick trim balance
>>  157 auto quick raid
>> --
>> 2.28.0
>>
> 
> 


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]