Re: kernel BUG at fs/btrfs/inode.c:4676!

[Josef Bacik <josef@redhat.com>]

On 06/10/2011 02:43 PM, Marek Otahal wrote:
> On Friday 10 of June 2011 15:33:20 Josef Bacik wrote:
>> On 06/09/2011 10:06 PM, Daniel J Blueman wrote:
>>> On 10 June 2011 09:57, Andy Lutomirski <luto@mit.edu> wrote:
>>>> On 06/06/2011 06:19 AM, Marek Otahal wrote:
>>>>>
>>>>> Hello,
>>>>> the issue happens every time when i have to hard power-off my notebook
>>>>> (suspend problems).
>>>>> With kernel 2.6.39 the partition is unmountable, solution is to boot
>>>>> 2.6.38 kernel which
>>>>> 1/ is able to mount the partition,
>>>>> 2/ by doing that fixes the problem so later .39 (after clean shutdown) can
>>>>> mount it also.
>>>>
>>>> Same problem here.  Mounting with 2.6.38 says:
>>>>
>>>> [   41.906259] Btrfs loaded
>>>> [   41.906747] device fsid e040a9d60da49596-66c0275e348878bf devid 1 transid
>>>> 69217 /dev/mapper/vg_midnight_ssd-home
>>>> [   41.908767] btrfs: disk space caching is enabled
>>>> [   42.232185] btrfs: unlinked 17 orphans
>>>> [   42.232189] btrfs: truncated 2 orphans
>>>>
>>>> dmesg in 2.6.39.1 says:
>>> []
>>>> [   15.004255] kernel BUG at fs/btrfs/inode.c:4676!
>>> []
>>>
>>> I've been experiencing the same issue also.
>>>
>>> Josef/Chris, would an metadata snapshot or full block snapshot help
>>> debug this regression? I can probably setup a small testcase to
>>> trigger this.
>>>
>>
>> If you can come up with a testcase to reproduce I would love you forever
>> ;).  If I get done what I wanted to do today I will try and reproduce.
>> Thanks,
>>
>> Josef
>>
> ...I was getting ready for you eternal love, Josef :P...but I can't reproduce it 100%, like 70% success-rate. 
> 
> The test-case is quite easy, 
> 1. mount the FS, just with compress-force=lzo option // I didn't try without, but on my other btrfs partition that doesn't use compression the err never happened ...so, can the others who experience the bug confirm compress=lzo used?   
> 2. cd to it & create a file (not sure if needed)
> 3. hard power-off
> 
> To reproduce my tests: 
> dd /dev/zero /btrfstest bs=1M count=256 (min required for default mksf.btrfs)
> losetup /dev/loop0 /btrfstest
> mkfs.btrfs /dev/loop0
> mount -o compress-force=lzo /dev/loop0 /mnt/tmp
> vim /mnt/tmp/hello.txt
> ---power off!

How long do you wait between these two steps?  I've not been able to
reproduce this and I've done it maybe 5 times.  Either I've fixed it in
my tree (yay!) or I'm doing something wrong (boo!).  Thanks,

Josef