On Mon, Oct 29, 2012 at 8:20 PM, Liu Bo <bo.li....@oracle.com> wrote:
> On 10/30/2012 04:06 AM, Mitch Harder wrote:
>> On Sat, Oct 27, 2012 at 5:28 AM, Liu Bo <bo.li....@oracle.com> wrote:
>>> This comes from one of btrfs's project ideas,
>>> As we defragment files, we break any sharing from other snapshots.
>>> The balancing code will preserve the sharing, and defrag needs to grow this
>>> as well.
>>>
>>> Now we're able to fill the blank with this patch, in which we make full use 
>>> of
>>> backref walking stuff.
>>>
>>> Here is the basic idea,
>>> o  set the writeback ranges started by defragment with flag EXTENT_DEFRAG
>>> o  at endio, after we finish updating fs tree, we use backref walking to 
>>> find
>>>    all parents of the ranges and re-link them with the new COWed file 
>>> layout by
>>>    adding corresponding backrefs.
>>>
>>> Originally patch by Li Zefan <l...@cn.fujitsu.com>
>>> Signed-off-by: Liu Bo <bo.li....@oracle.com>
>>> ---
>>> v3->v4:
>>>       - fix duplicated refs bugs detected by mounting with autodefrag, 
>>> thanks
>>>         for the bug report from Mitch and Chris.
>>>
>>
>> I'm picking up many WARN_ON messages while testing this patch.
>>
>> I'm testing a snapshot script that uses kernel git sources along with
>> some git manipulations.
>>
>> The kernel is a 3.6.4 kernel merged with the latest for-linus branch.
>>
>> I mounted with -o compress-force=lzo,autodefrag.
>>
>> I also have the second patch in this set (Btrfs: make snapshot-aware
>> defrag as a mount option).  However, I did not mount with
>> 'snap_aware_defrag'.
>>
>> I did not find any corrupted data, and the partition passes a btrfsck
>> without error after these warnings were observed.
>>
>
> Hi Mitch,
>
> Well, good report, but I don't think it has anything to do with this 
> patch(since you
> didn't mount with 'snap_aware_defrag' :)
>

I've re-run my my testing script with a combination of no compression
and lzo compression, combined with no further options, only -o
autodefrag, and -o autodefrag,snap_aware_defrag.

I only get the WARN_ONs when I run with autodefrag only (no snap_aware_defrag).

My logs are clean when I avoid all defrag options, or use both
autodefrag and snap_aware_defrag.

> After going through the below messages, the bug comes from the space side 
> where we
> must have mis-used our reservation somehow.
>
> So can you show me your script so that I can give it a shot to reproduce 
> locally?
>
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