Re: BTRFS error in __btrfs_inc_extent_ref:1935: Object already exists

[Roman Mamedov <rm@romanrm.ru>]

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On Mon, 1 Apr 2013 04:36:05 +0600
Roman Mamedov <rm@romanrm.ru> wrote:

> Hello,
> 
> After a reboot the filesystem now does not mount at all, with similar messages.

So thinking this was an isolated incident, I foolishly continued setting up
scheduled balance on other systems with btrfs that I have.

And got into exactly the same situation on another machine!!

Trying to balance this with -dusage=5, on kernel 3.8.5:

Data: total=215.01GB, used=141.76GB
System, DUP: total=32.00MB, used=32.00KB
System: total=4.00MB, used=0.00
Metadata, DUP: total=9.38GB, used=1.09GB

Same messages, "Object already exists".

While I currently left the previously mentioned 2TB FS in an unmounted broken
state, still waiting for any response from you on how to properly recover from
this problem, in this new case I needed to restore the machine as soon as
possible.

I tried btrfsck --repair, it corrected a lot of errors, but in the end gave up
with a message saying that it can't repair the filesystem; then I did
btrfs-zero-log. After this the FS started mounting successfully again.

Not sure if I got any data corruption as a result, but this is the root FS
and /home, and the machine successfully booted up with no data lost in any of
the apps that were active just before the crash (e.g browser, IM and IRC
clients), so probably not.

-- 
With respect,
Roman

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