Re: Help Dealing with BTRFS errors on a root partition in NVMe M2 PCIe

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

On 2021/7/24 下午5:25, Fernando Peral wrote:
> Hi.
>
> I'm having an error on the root partition of a opensuse leap 15.3 system.
>
> I have been asking for help in the opensuse forums
>
> The problem seems to have been caused by a faulty ram module wich has
> been already replaced, but the error of the fs is still there.
>
> It has been suggested that it has been a bitflip and to ask here if a
> btrfs check and repair should be done. >
>
>
> #btrfs
> check --readonly --force /dev/nvme0n1p1
> [1/7] checking root items
> [2/7] checking extents
> data backref 227831808 root 263 owner 7983 offset 0 num_refs 0 not found
> in extent tree
> incorrect local backref count on 227831808 root 263 owner 7983 offset 0
> found 1 wanted 0 back 0x5559e0ab7020
> incorrect local backref count on 227831808 root 263 owner
> 140737488363311offset 0 found 0 wanted 1 back 0x5559dde718d0

The owner number 140737488363311 (0x800000001f2f) really looks like a
bitflip in the high bit.

Thus the faulty memory theory looks pretty solid.

So far just two bad EXTENT_ITEM, I think btrfs check --repair is able to
fix it.

But before calling "btrfs check --repair", please backup all your
important data, as there is still a low chance that "btrfs check
--repair" may make things worse.

Thanks,
Qu

> backref disk bytenr does not match extent record, bytenr=227831808, ref
> bytenr=0
> backpointer mismatch on [227831808 4096]
> ERROR: errors found in extent allocation tree or chunk allocation
> [3/7]checking free space cache
> [4/7]checking fs roots
> [5/7]checking only csums items (without verifying data)
> [6/7]checking root refs
> [7/7]checking quota groups
> Qgroup are marked as inconsistent.
> Opening filesystem to check...
> Checking filesystem on /dev/nvme0n1p1
> UUID: 5b000355-3a1a-49f5-8005-f10668008aa7
> Rescan hasn't been initialized, a difference in qgroup accounting is
> expected
> found 51878920192 bytes used, error(s) found
> total csum bytes: 48135312
> total tree bytes: 991313920
> total fs tree bytes: 885358592
> total extent tree bytes: 48414720
> btree space waste bytes: 151592274
> file data blocks allocated: 239972728832
> referenced 85539778560
>
>
> pruebas:~# uname -a
> Linux pruebas 5.3.18-59.13-default #1 SMP Tue Jul 6
> 07:33:56 UTC 2021 (23ab94f) x86_64 x86_64 x86_64 GNU/Linux
>
>
> pruebas:~#btrfs --version
> btrfs-progs v4.19.1  ç
>
> pruebas:~# btrfs fi show
> Label: none  uuid: 5b000355-3a1a-49f5-8005-f10668008aa7
> Totaldevices 1 FS bytes used 48.42GiB
> devid  1 size 931.51GiB used 51.05GiB path /dev/nvme0n1p1
>
>
> pruebas:~#btrfs fi df /
> Data, single: total=49.01GiB, used=47.48GiB
> System, single: total=32.00MiB, used=16.00KiB
> Metadata, single: total=2.01GiB, used=962.69MiB
> GlobalReserve, single: total=101.06MiB, used=0.00B
>
>