Re: [PATCH] generic: check whether we can truncate heavily reflinked file

[Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>]

Hi,

On 09/12/2016 05:18 PM, Eryu Guan wrote:
> On Mon, Sep 12, 2016 at 02:36:59PM +0800, Wang Xiaoguang wrote:
>> Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
> It's better to describe the test a bit in the commit log, e.g. why this
> test is needed etc., which at least could give us some historical
> information when we look at this case again some time later. I guess
> there's a btrfs bug that truncate would fail due to ENOSPC.
OK.

>
>> ---
>>   tests/generic/377     | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>   tests/generic/377.out |  2 ++
>>   tests/generic/group   |  1 +
>>   3 files changed, 77 insertions(+)
>>   create mode 100755 tests/generic/377
>>   create mode 100644 tests/generic/377.out
>>
>> diff --git a/tests/generic/377 b/tests/generic/377
>> new file mode 100755
>> index 0000000..3a0c27e
>> --- /dev/null
>> +++ b/tests/generic/377
>> @@ -0,0 +1,74 @@
>> +#! /bin/bash
>> +# FS QA Test 377
>> +#
>> +# Create a heavily reflinked file, then check whether we can truncate
>> +# it correctly.
>> +#
>> +#-----------------------------------------------------------------------
>> +# Copyright (c) 2016 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()
>> +{
>> +	cd /
>> +	rm -f $tmp.*
>> +}
>> +
>> +# get standard environment, filters and checks
>> +. ./common/rc
>> +. ./common/filter
>> +. ./common/reflink
>> +
>> +# remove previous $seqres.full before test
>> +rm -f $seqres.full
>> +
>> +# Modify as appropriate.
>> +_supported_fs generic
>> +_supported_os Linux
>> +_require_scratch
>> +_require_scratch_reflink
>> +_require_cp_reflink
> cp is not used, so this "require" is not needed.
>
>> +
>> +_scratch_mkfs_sized $((128 * 1024 * 1024)) >> $seqres.full 2>&1
>> +_scratch_mount
>> +
>> +file=$SCRATCH_MNT/testfile
>> +blocksize=$((128 * 1024))
>> +
>> +# create the initial file.
>> +_pwrite_byte 0xcdcdcdcd 0 $blocksize  $file > /dev/null
>> +
>> +echo "Silence is golden"
>> +# filesize is 20GB, and here 20GB is choosen deliberately, so it
>> +# can consume enough fs free space.
>> +for ((i=1; i<163840; i++)); do
>> +	_reflink_range $file 0 $file $(($i * $blocksize)) $blocksize \
>> +		>> $seqres.full 2>&1
>> +done
>> +$XFS_IO_PROG -f -c 'truncate 0' $file
> This took me more than 10 minutes to finish on my test vm (4vcpu and 8G
> memory), 980s for XFS and 700s for btrfs(truncate failed due to ENOSPC).
> That's too long for an 'auto' test.
>
> Can the runtime be reduced? I'm not sure how long time it took for you,
> but it would be good to have it finish around 5 minutes.
OK, I'll try to reduce the test time.
It took me about 2 minutes. For you, I think it's "btrfsck device" which
run so long time, for heavily reflinked file, btrfsck does not perform well.

Regards,
Xiaoguang Wang
>
> Thanks,
> Eryu
>
>> +
>> +status=0
>> +exit
>> diff --git a/tests/generic/377.out b/tests/generic/377.out
>> new file mode 100644
>> index 0000000..d14a512
>> --- /dev/null
>> +++ b/tests/generic/377.out
>> @@ -0,0 +1,2 @@
>> +QA output created by 377
>> +Silence is golden
>> diff --git a/tests/generic/group b/tests/generic/group
>> index bad71bc..ea98752 100644
>> --- a/tests/generic/group
>> +++ b/tests/generic/group
>> @@ -379,3 +379,4 @@
>>   374 auto quick clone dedupe
>>   375 auto quick acl
>>   376 auto quick metadata
>> +377 auto clone
>> -- 
>> 2.9.0
>>
>>
>>
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