Re: Upgraded from Buster to Bullseye, unmountable Btrfs filesystem

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2021/11/10 22:01, S. wrote:
>
> On 11/10/21 02:01, Qu Wenruo wrote:
>> If you can revert to older kernel/distro, then you can mount the fs with
>> "-o rescan_uuid" to regenerate the UUID tree using the old kernel.
>>
>> Then it would rebuild the UUID tree, no need for a tool in user space.
>
> Thanks very much for the explanation and for the suggestions.
> Fortunately the system saved a copy of the old 4.19 kernel and initrd
> image. You are correct that the old kernel can still boot the filesystem
> without errors. Then I unmounted it and remounted it with `-o
> rescan_uuid_tree`. This also appeared to work, as it was able to mount.
> However, after rebooting into the new Bullseye kernel the filesystem is
> still unmountable:
>
> ------------------------
> [  115.250774] BTRFS info (device sda3): flagging fs with big metadata
> feature
> [  115.257773] BTRFS info (device sda3): disk space caching is enabled
> [  115.264089] BTRFS info (device sda3): has skinny extents
> [  115.414229] BTRFS critical (device sda3): corrupt leaf: root=9
> block=170459136 slot=0, invalid key objectid, have 1101835439474057344
> expect to be aligned to 4096r
> [  115.428780] BTRFS error (device sda3): block=170459136 read time tree
> block corruption detected
> [  115.459643] BTRFS critical (device sda3): corrupt leaf: root=9
> block=170459136 slot=0, invalid key objectid, have 1101835439474057344
> expect to be aligned to 4096
> [  115.474296] BTRFS error (device sda3): block=170459136 read time tree
> block corruption detected
> [  115.483109] BTRFS warning (device sda3): failed to read root
> (objectid=9): -5
> [  115.534748] BTRFS error (device sda3): open_ctree failed
> ------------------------

After a deeper look into the uuid rescan code, it doesn't delete those
corrupted keys, but only add back correct items.

So it means, we still need btrfs-progs to repair it.

Thus I believe you still need to prepare a build environment for it.

For the worst case, I could try to build a static btrfs-progs for you if
you could provide the "uname -a" output.

Thanks,
Qu
>
> Any more ideas? Thanks again.