Re: kernel 3.8.8: btrfs still crashes on boot when it can't replay a log

[Josef Bacik <jbacik@fusionio.com>]

On Thu, May 16, 2013 at 09:09:18AM -0600, Marc MERLIN wrote:
> I've reported this bug a few times over different kernel versions over the
> last year now, and unfortunately it's still not fixed as of 3.8 (yes, I know
> 3.9 is out, I'm just about to switch).
> 
> What happens as far as I know:
> I have btrfs on top of dmcrypt on an SDD.
> 
> The SSD on occasion seems to just hang, so I have to power cycle my laptop.
> I can't say how much the SSD did and did not write before stopping to work.
> 
> Then, maybe one time out of 2 or 3, btrfs crashes when I reboot and it tries 
> to replay the log.
> 
> I'm then forced to do this from emergency boot media:
> 
> gandalfthegreat:~# btrfs-zero-log /dev/mapper/root                                                        
> Check tree block failed, want=64855564288, have=14954667565421255623                                      
> Check tree block failed, want=64855564288, have=14954667565421255623                                      
> Check tree block failed, want=64855564288, have=7474503720151340134                                       
> Check tree block failed, want=64855564288, have=14954667565421255623                                      
> Check tree block failed, want=64855564288, have=14954667565421255623                                      
> read block failed check_tree_block   
> 
> The last bits of the crash before I zero the log:
> http://marc.merlins.org/tmp/btrfs-3.8.8.jpg
> 
> Still issues with btrfs_numb_copies.
> 
> This has been going on for over a year now, not very pleasant :)
> 
> Is there no way you can corrupt logs in a test lab and reproduce this?
> 
> Or is it still known to happen due to missing code that decides whether a log is corrupt 
> and whether to discard it before the code reads it and crashes?
> 
> If so, could you add this to the list of things to fix to make btrfs a bit
> less scary to others? :)
> (and of course more production ready, this repeated problem would kill any
> server it happens on)
> 

This has been all fixed in 3.10.  Thanks,

Josef