Re: 3.18.0: kernel BUG at fs/btrfs/relocation.c:242!

[Robert White <rwhite@pobox.com>]

On 12/12/2014 02:46 PM, Tomasz Chmielewski wrote:
> On 2014-12-12 23:34, Robert White wrote:
>> On 12/12/2014 01:46 PM, Tomasz Chmielewski wrote:
>>> On 2014-12-12 22:36, Robert White wrote:
>>>
>>>> In another thread [that was discussing SMART] you talked about
>>>> replacing a drive and then needing to do some patching-up of the
>>>> result because of drive failures. Is this the same filesystem where
>>>> that happened?
>>>
>>> Nope, it was on a different server.
>>>
>>
>> okay, so how did the btrfsck turn out?
>
> # time btrfsck /dev/sdc1 &>/root/btrfsck.log
>
> real    22m0.140s
> user    0m3.090s
> sys     0m6.120s
>
> root@bkp010 /usr/src/btrfs-progs # echo $?
> 1
>
> # cat /root/btrfsck.log
> root item for root 8681, current bytenr 5568935395328, current gen
> 70315, current level 2, new bytenr 5569014104064, new gen 70316, new
> level 2
> Found 1 roots with an outdated root item.
> Please run a filesystem check with the option --repair to fix them.
>
>
> Now, I'm a bit afraid to run --repair - as far as I remember, some time
> ago, it used to do all weird things except the actual repair.
> Is it better nowadays? I'm using latest clone from
> git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git
>
>

I don't have the history to answer this definitively, but I don't think 
you have a choice. Nothing else is going to touch that error.

I have not seen any "oh my god, btrfsck just ate my filesystem errors" 
since I joined the list -- but I am a relative newcomer.

I know that you, of course, as a contentious and well-traveled system 
administrator, already have a current backup since you are doing storage 
maintenance... right? 8-)