Re: Tree-checker Issue / Corrupt FS after upgrade ?

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

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On 2020/8/13 上午12:58, benjamin.haendel@gmx.net wrote:
> Hi,
> 
> i have been running my little Storage (32TB) on a Ubuntu 18.04 LTS Machine
> with btrfs-progs 4.17. I then did my monthly upgrade (apt dist-upgrade) and
> after a reboot my Partition could not mount with the error message: 
> "root@Userv:/home/benjamin# mount -r ro btrfs /dev/mapper/Crypto
> /media/Storage
> mount: bad usage"
> 
> I then proceeded to run a btrfs check which gave thousands of errors and
> then also a super-recover:
> root@Userv:/home/benjamin# btrfs rescue super-recover -v /dev/mapper/Crypto
> All Devices:
> Device: id = 1, name = /dev/mapper/Crypto
> 
> Before Recovering:
> [All good supers]:
> device name = /dev/mapper/Crypto
> superblock bytenr = 65536
> 
> device name = /dev/mapper/Crypto
> superblock bytenr = 67108864
> 
> device name = /dev/mapper/Crypto
> superblock bytenr = 274877906944
> 
> [All bad supers]:
> 
> All supers are valid, no need to recover
> 
> I now checked my dmesg log:
> [45907.451840] BTRFS critical (device dm-0): corrupt leaf:
> block=22751711027200 slot=1 extent bytenr=6754755866624 len=4096 invalid
> generation, have 22795412619264 expect (0, 207589]

This is caused by older kernel, which writes some uninitialized value
onto disk.

You can try to fix it with this branch:
https://github.com/adam900710/btrfs-progs/tree/extent_gen_repair

Or you can use older kernel to delete the offending extents.

Thanks,
Qu

> [45907.451848] BTRFS error (device dm-0): block=22751711027200 read time
> tree block corruption detected
> [45907.451892] BTRFS error (device dm-0): failed to read block groups: -5
> [45907.510712] BTRFS error (device dm-0): open_ctree failed
> 
> Google inquiries to this topic led me to this link:
> https://btrfs.wiki.kernel.org/index.php/Tree-checker
> It tells me to mail here first so thats what i am doing. I kind of suspect
> since everything worked perfect (Memtest also no errors) before the update,
> it has to do something with that update. I am wondering if it would help if
> i deleted my OS Disk and reinstalled an older Version of Ubuntu, like
> 16.04.6 LTS ?
> 
> Since then i upgraded to 20.04 LTS with BTRFS-PROGS 5.7 as a lot of forum
> entries said it would be wise to use the newer versions as older were buggy.
> That brought no help as well.
> 
> Since i am no Linux/Unix Expert i thought it might be better to ask now
> first as advised in the link above before proceeding with any other plans.
> 
> I find it hard to believe that all data is gone, i feel its buggy behavior
> as the partition and everything is still there:
> root@Userv:/home/benjamin# btrfs fi show
> Label: 'Storage'  uuid: 46c7d04a-d6ac-45be-94cc-724919faca2b
> Total devices 1 FS bytes used 28.23TiB
> devid    1 size 29.10TiB used 29.04TiB path /dev/mapper/Crypto
> 
> Best Regards,
> Benjamin Händel
> 


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