Re: [PATCH] xfstests: Add message indicating btrfs-progs support FST in read-only mode

From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Eryu Guan <eguan@redhat.com>, Gu Jinxiang <gujx@cn.fujitsu.com>
Cc: fstests@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] xfstests: Add message indicating btrfs-progs support FST in read-only mode
Date: Thu, 26 Oct 2017 15:13:25 +0800	[thread overview]
Message-ID: <53ac8baa-1a31-a428-b02f-ecd32fb5222f@gmx.com> (raw)
In-Reply-To: <20171026065218.GK3235@eguan.usersys.redhat.com>

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On 2017年10月26日 14:52, Eryu Guan wrote:
> On Thu, Oct 26, 2017 at 01:57:46PM +0800, Gu Jinxiang wrote:
>> From: Gu JinXiang <gujx@cn.fujitsu.com>
>>
>> btrfs-progs now support FST in read-only mode, so when space_cache=v2
>> enabled, this test case will fail.
>> Add message to help user to understand this status.
> 
> Sorry, I don't quite understand the new 'FST' feature.

FST is Free Space (cache) Tree, which is one of the internal methods to
manage the free space cache for btrfs.

> But is it a bug
> that we want to fix when mounting with space_cache=v2 option, or we just
> couldn't do btrfs-convert in this case? If it's a real bug, I'd say let
> the test fail as it is, and track bug in tools like bugzilla not
> comments/messages in the test; if it's the latter case, then just
> _notrun the test if space_cache=v2 option is specified, e.g.

The problem is not about the kernel, it's btrfs-convert to blame, which
can't handle free space cache tree.

However, since btrfs-convert is just rollbacking the btrfs to ext*, it
doesn't really need to do any write to *btrfs*, so the correct method
here is to fix btrfs-convert rollback, to do a *readonly* open other
than RW open, other than skipping special mount option.

I'll fix it soon.

Thanks,
Qu

> 
> _exclude_scratch_mount_option "space_cache=v2"
> 
> Thanks,
> Eryu
> 
>>
>> Signed-off-by: Gu JinXiang <gujx@cn.fujitsu.com>
>> ---
>>  tests/btrfs/012 | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/tests/btrfs/012 b/tests/btrfs/012
>> index 85c82f07..529e6eca 100755
>> --- a/tests/btrfs/012
>> +++ b/tests/btrfs/012
>> @@ -96,6 +96,12 @@ cp -aR /lib/modules/`uname -r`/ $SCRATCH_MNT/new
>>  
>>  _scratch_unmount
>>  
>> +space_cache_version=$(echo "$MOUNT_OPTIONS" | grep "space_cache=v2")
>> +if [ -n "$space_cache_version" ]; then
>> +	_fail "since used space_cache=v2 when mount," \
>> +	       "and for FST btrfs-progs support is read-only."\
>> +	      "so btrfs-convert rollback will fail"
>> +fi
>>  # Now restore the ext4 device
>>  $BTRFS_CONVERT_PROG -r $SCRATCH_DEV >> $seqres.full 2>&1 || \
>>  	_fail "btrfs-convert rollback failed"
>> -- 
>> 2.13.5
>>
>>
>>
>> --
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