Re: [PATCH] fstest: btrfs/083: Test for incorrect exclusive refernce number after file clone.

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

-------- Original Message  --------
Subject: Re: [PATCH] fstest: btrfs/083: Test for incorrect exclusive 
refernce number after file clone.
From: Filipe David Manana <fdmanana@gmail.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2015年03月12日 20:38

> On Tue, Mar 10, 2015 at 7:46 AM, Qu Wenruo <quwenruo@cn.fujitsu.com> wrote:
>> [Problem]
>> Since commit fcebe4562dec83b3f8d308 ("Btrfs: rework qgroup accounting"),
>> quota data update is delayed after delayed_ref calculation, and lacks
>> correct protection to detect root reference which shouldn't be counted
>> in current sequence number but already written into extent backref.
>>
>> This makes exclusive reference not decreased correctly and give incorrect
>> result.
>>
>> [Test procedure]
>> 1. Create a btrfs with 3 subvolumes, quota enabled and rescanned.
>> 2. Create a file in 1st subvolume
>> 3. Clone the file to 2nd and 3rd subvolume
>> 4. Sync the fs to reflect the changes in qgroup.
>> 5. Check the qgroup data
>>
>> [Expected result]
>> None of the subvolume has exclusive reference to the file.
>>
>> [Actual result]
>> The first subvolume still have exclusive reference to the file.
>>
>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>> ---
>>   tests/btrfs/083     | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   tests/btrfs/083.out |  5 ++++
>>   tests/btrfs/group   |  1 +
>>   3 files changed, 82 insertions(+)
>>   create mode 100755 tests/btrfs/083
>>   create mode 100644 tests/btrfs/083.out
>>
>> diff --git a/tests/btrfs/083 b/tests/btrfs/083
>> new file mode 100755
>> index 0000000..17fd30b
>> --- /dev/null
>> +++ b/tests/btrfs/083
>> @@ -0,0 +1,76 @@
>> +#! /bin/bash
>> +# FS QA Test No. 083
>> +#
>> +# Test for incorrect exclusive reference count after cloning file
>> +# between subvolumes.
>> +#
>> +#-----------------------------------------------------------------------
>> +# Copyright (c) 2015 Fujitsu. All Rights Reserved.
>> +#
>> +# 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()
>> +{
>> +    rm -f $tmp.*
>> +}
>> +
>> +# get standard environment, filters and checks
>> +. ./common/rc
>> +. ./common/filter
>> +
>> +# real QA test starts here
>> +
>> +# Modify as appropriate.
>> +_need_to_be_root
>> +_supported_fs btrfs
>> +_supported_os Linux
>> +_require_scratch
>> +_require_cp_reflink
>> +
>> +run_check _scratch_mkfs "--nodesize 4096"
>
> --nodesize 65536
> Otherwise the test fails (unnecessarily) on platforms with a page size > 4Kb.
>
>> +
>> +# inode cache will also take space in fs tree, disable them to get consistent
>> +# result.
>> +run_check _scratch_mount "-o noinode_cache"
>
> -o noinode_cache, unlike -o inode_cache, is still a relatively new
> mount option (early 2014). Won't the test fail on older kernels that
> don't recognize this mount option?
>
>> +
>> +_run_btrfs_util_prog subvolume create $SCRATCH_MNT/subv1
>> +_run_btrfs_util_prog subvolume create $SCRATCH_MNT/subv2
>> +_run_btrfs_util_prog subvolume create $SCRATCH_MNT/subv3
>> +
>> +_run_btrfs_util_prog quota enable $SCRATCH_MNT
>> +_run_btrfs_util_prog quota rescan -w $SCRATCH_MNT
>> +
>> +dd if=/dev/zero of=$SCRATCH_MNT/subv1/file1 bs=4K count=64 &> /dev/null
>
> Why ignore dd failures? Normally we want the output (specially errors)
> to be matched against the golden output.
Indeed, will redirect error output into $seq.full in next version.
>
>> +cp --reflink $SCRATCH_MNT/subv1/file1 $SCRATCH_MNT/subv2/file1
>> +cp --reflink $SCRATCH_MNT/subv1/file1 $SCRATCH_MNT/subv3/file1
>> +_run_btrfs_util_prog filesystem sync $SCRATCH_MNT
>
> Plain old 'sync' should work here as well.

Yes, old sync will do it, but I prefer not to touch other unrelated fs, 
so I chose 'btrfs fi sync' which only involve the scratch mount.

Other comment is inlined in reply to Josef.

Thanks,
Qu
>
> thanks Qu
>
>> +
>> +units=`_btrfs_qgroup_units`
>> +$BTRFS_UTIL_PROG qgroup show $units $SCRATCH_MNT | $SED_PROG -n '/[0-9]/p' \
>> +       | $AWK_PROG '{print $2" "$3}'
>> +
>> +# success, all done
>> +status=0
>> +exit
>> diff --git a/tests/btrfs/083.out b/tests/btrfs/083.out
>> new file mode 100644
>> index 0000000..359b4a0
>> --- /dev/null
>> +++ b/tests/btrfs/083.out
>> @@ -0,0 +1,5 @@
>> +QA output created by 083
>> +4096 4096
>> +266240 4096
>> +266240 4096
>> +266240 4096
>> diff --git a/tests/btrfs/group b/tests/btrfs/group
>> index fd2fa76..04d5d67 100644
>> --- a/tests/btrfs/group
>> +++ b/tests/btrfs/group
>> @@ -85,3 +85,4 @@
>>   080 auto snapshot
>>   081 auto quick clone
>>   082 auto quick remount
>> +083 auto quick qgroup
>> --
>> 2.3.1
>>
>> --
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>
>