Re: Updated to new kernel, and btrfs suddenly refuses to mount home directory fs.

[Chris Murphy <lists@colorremedies.com>]

On Tue, Mar 8, 2022 at 12:05 PM bill gates <framingnoone@gmail.com> wrote:
>
> So, I recently attempted to upgrade from Linux kernel 4.19.82 to
> 5.15.23, and I'm getting a critical error in dmesg about a corrupt
> leaf (and no mounting of /home allowed with the options I'm aware of)
>
> [ 396.218964] BTRFS critical (device sda2): corrupt leaf: root=1
> block=10442806968320 sl
> ot=8 ino=6, invalid location key objectid: has 1 expect 6 or [256,
> 18446744073709551360]
> or 18446744073709551604
> [ 396.218967] BTRFS error (device sda2): block=10442806968320 read
> time tree block corru
> ption detected
>
>
> Interestingly. that 18446... number is a power of 2, looks like maybe
> a bit flip? dmesg, uname, etc included in pastebin below. "btrfs
> check" found no problems with fs on either kernel version. Would like
> to figure out how to fix this, if possible.

The read time tree checker was added in 4.18 but there were
enhancements in ~5.1 to 5.3. This could be a bug introduced into the
file system from an older kernel.

I'm not sure why btrfs check isn't seeing it. What version of btrfs-progs?

You can recover by copying the affected files out of this file system
to a new one while using a current 4.19 series kernel. It won't hit
the tree checker error. One strategy could be making read-only
snapshots and using btrfs send receive to replicate to a new btrfs
file system, using 4.19 kernel. If you can isolate the problem being
triggered to just a file or a directory - you could copy that
directory to another file system, delete it, and then copy it back.


-- 
Chris Murphy