Re: bad tree block start, want 705757184 have 82362368

[Stephan Olbrich <stephanolbrich@gmx.de>]

Am Freitag, 16. November 2018, 17:44:35 CET schrieb Nikolay Borisov:
> On 16.11.18 г. 18:17 ч., Stephan Olbrich wrote:
> > Hi,
> > 
> > a few days ago my root file system (simple btrfs on a SSD, no RAID or
> > anything) suddenly became read only. Looking at dmsg, I found this:
> > 
> > [   19.285020] BTRFS error (device sda2): bad tree block start, want
> > 705757184 have 82362368 [   19.285042] BTRFS: error (device sda2) in
> > __btrfs_free_extent:6804: errno=-5 IO failure [   19.285048] BTRFS info
> > (device sda2): forced readonly
> > [   19.285051] BTRFS: error (device sda2) in btrfs_run_delayed_refs:2934:
> > errno=-5 IO failure [   19.287213] BTRFS error (device sda2): pending
> > csums is 41889792
> > 
> > Late on I got the same errors for my /home partition (on the same drive)
> > as well. I have snapshots of all partitions on another drive made by
> > btrbk. To get a working system, I made new (rw) snapshots of the most
> > recent backup and setup grub and fstab, so my system would boot from the
> > other drive. Unfortunately now I got the "bad tree block start" error
> > again at least once in dmesg but I didn't save it and it's not in syslog
> > :-( What I remember is, that it was followed by other btrfs error
> > messages saying something about correcting something. And the filesystem
> > was still read/write this time.
> > At the moment I can't reproduce it.
> > 
> > Is there any way to find out, which files are affected by the errors
> > above? I don't really trust the data on the drive I'm using at the
> > moment, as it has shown errors as well, but I have a less current backup
> > on yet another drive but at it is a few weeks old, I don't want to use it
> > to setup the system on the SSD again, but just copy the relevant files if
> > possible. Or is it possible to repair the original file system?
> > 
> > Some information about my system:
> > Kubuntu 18.04
> > Kernel 4.19.1 when the problem occured, now 4.19.2
> > btrfs-tools 4.15.1
> 
> What is the SMART status of your SSD, how old is the ssd. This really
> sounds like the drive going to lalal land.

The SSD is 3.5 years old and was never really full, so I wouldn't expect it to 
die. SMART shows no errors. All values are way above the threshold and 
selftests show no errors.
I checked RAM as well. No errors there, so I have no clue, where these errors 
come from.

Regards,
Stephan