fix for ERROR: cannot read chunk root

fix for ERROR: cannot read chunk root

[Sergiu Cozma]

hi, i need some help to recover a btrfs partition
i use btrfs-progs v5.3.1

btrfs rescue super-recover https://pastebin.com/mGEp6vjV
btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa

can't mount the partition with
BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
[ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
[ 2295.301067] BTRFS error (device sdb4): open_ctree failed

Re: fix for ERROR: cannot read chunk root

[Sergiu Cozma]

also btrfs check --readonly /dev/sdb4
Opening filesystem to check...
checksum verify failed on 856119312384 found 000000B6 wanted 00000000
checksum verify failed on 856119312384 found 000000B6 wanted 00000000
bad tree block 856119312384, bytenr mismatch, want=856119312384, have=0
ERROR: cannot read chunk root
ERROR: cannot open file system

On Tue, Nov 5, 2019 at 5:04 PM Sergiu Cozma <lssjbrolli@gmail.com> wrote:
>
> hi, i need some help to recover a btrfs partition
> i use btrfs-progs v5.3.1
>
> btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
>
> can't mount the partition with
> BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
> [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> [ 2295.301067] BTRFS error (device sdb4): open_ctree failed

Re: fix for ERROR: cannot read chunk root

[Qu Wenruo]

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On 2019/11/5 下午11:04, Sergiu Cozma wrote:
> hi, i need some help to recover a btrfs partition
> i use btrfs-progs v5.3.1
> 
> btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
> 
> can't mount the partition with
> BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0

Something wiped your fs on-disk data.
And the wiped one belongs to one of the most essential tree, chunk tree.

What's the history of the fs?
It doesn't look like a bug in btrfs, but some external thing wiped it.

Thanks,
Qu

> [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
> 


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Re: fix for ERROR: cannot read chunk root

[Sergiu Cozma]

Hi, thanks for taking the time to help me out with this.

The history is kinda bad, I tried to resize the partition but gparted
failed saying that the the fs has errors and after throwing some
commands found on the internet at it now I'm here :(

Any chance to recover or rebuild the chunk tree?


On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>
>
>
> On 2019/11/5 下午11:04, Sergiu Cozma wrote:
> > hi, i need some help to recover a btrfs partition
> > i use btrfs-progs v5.3.1
> >
> > btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> > btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> > btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
> >
> > can't mount the partition with
> > BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
>
> Something wiped your fs on-disk data.
> And the wiped one belongs to one of the most essential tree, chunk tree.
>
> What's the history of the fs?
> It doesn't look like a bug in btrfs, but some external thing wiped it.
>
> Thanks,
> Qu
>
> > [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> > [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
> >
>

Re: fix for ERROR: cannot read chunk root

[Sergiu Cozma]

btrfs inspect-internal dump-super -af /dev/sdb4 | grep chunk_root
chunk_root_generation   687369
chunk_root              856119312384
chunk_root_level        1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
chunk_root_generation   687369
chunk_root              856119312384
chunk_root_level        1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
chunk_root_generation   687369
chunk_root              856119312384
chunk_root_level        1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1
               backup_chunk_root:      856119312384    gen: 687369     level: 1

if i understand this correctly there is only one copy of the chunk
root in the whole fs and mine is corrupted?

On Wed, Nov 6, 2019 at 5:52 PM Sergiu Cozma <lssjbrolli@gmail.com> wrote:
>
> Hi, thanks for taking the time to help me out with this.
>
> The history is kinda bad, I tried to resize the partition but gparted
> failed saying that the the fs has errors and after throwing some
> commands found on the internet at it now I'm here :(
>
> Any chance to recover or rebuild the chunk tree?
>
>
> On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
> >
> >
> >
> > On 2019/11/5 下午11:04, Sergiu Cozma wrote:
> > > hi, i need some help to recover a btrfs partition
> > > i use btrfs-progs v5.3.1
> > >
> > > btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> > > btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> > > btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
> > >
> > > can't mount the partition with
> > > BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
> >
> > Something wiped your fs on-disk data.
> > And the wiped one belongs to one of the most essential tree, chunk tree.
> >
> > What's the history of the fs?
> > It doesn't look like a bug in btrfs, but some external thing wiped it.
> >
> > Thanks,
> > Qu
> >
> > > [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> > > [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
> > >
> >

Re: fix for ERROR: cannot read chunk root

[Sergiu Cozma]

additional info: it's a simple partition on a samsung 840evo ssd, no
encryption, no md, no raid
 mount flags rw,relatime,ssd,space_cache,subvolid=5,subvol=/ mounted as /home
and it's pretty old(couple of years) and i'm like 70% sure it was
converted from ext4

On Wed, Nov 6, 2019 at 6:21 PM Sergiu Cozma <lssjbrolli@gmail.com> wrote:
>
> btrfs inspect-internal dump-super -af /dev/sdb4 | grep chunk_root
> chunk_root_generation   687369
> chunk_root              856119312384
> chunk_root_level        1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
> chunk_root_generation   687369
> chunk_root              856119312384
> chunk_root_level        1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
> chunk_root_generation   687369
> chunk_root              856119312384
> chunk_root_level        1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>                backup_chunk_root:      856119312384    gen: 687369     level: 1
>
> if i understand this correctly there is only one copy of the chunk
> root in the whole fs and mine is corrupted?
>
> On Wed, Nov 6, 2019 at 5:52 PM Sergiu Cozma <lssjbrolli@gmail.com> wrote:
> >
> > Hi, thanks for taking the time to help me out with this.
> >
> > The history is kinda bad, I tried to resize the partition but gparted
> > failed saying that the the fs has errors and after throwing some
> > commands found on the internet at it now I'm here :(
> >
> > Any chance to recover or rebuild the chunk tree?
> >
> >
> > On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
> > >
> > >
> > >
> > > On 2019/11/5 下午11:04, Sergiu Cozma wrote:
> > > > hi, i need some help to recover a btrfs partition
> > > > i use btrfs-progs v5.3.1
> > > >
> > > > btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> > > > btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> > > > btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
> > > >
> > > > can't mount the partition with
> > > > BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
> > >
> > > Something wiped your fs on-disk data.
> > > And the wiped one belongs to one of the most essential tree, chunk tree.
> > >
> > > What's the history of the fs?
> > > It doesn't look like a bug in btrfs, but some external thing wiped it.
> > >
> > > Thanks,
> > > Qu
> > >
> > > > [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> > > > [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
> > > >
> > >

Re: fix for ERROR: cannot read chunk root

[Qu Wenruo]

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On 2019/11/6 下午11:52, Sergiu Cozma wrote:
> Hi, thanks for taking the time to help me out with this.
> 
> The history is kinda bad, I tried to resize the partition but gparted
> failed saying that the the fs has errors and after throwing some
> commands found on the internet at it now I'm here :(

Not sure how gparted handle resize, but I guess it should use
btrfs-progs to do the resize?

> 
> Any chance to recover or rebuild the chunk tree?

I don't think so. Since it's wiped, there is no guarantee that only
chunk tree is wiped.

THanks,
Qu


> 
> 
> On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>
>>
>>
>> On 2019/11/5 下午11:04, Sergiu Cozma wrote:
>>> hi, i need some help to recover a btrfs partition
>>> i use btrfs-progs v5.3.1
>>>
>>> btrfs rescue super-recover https://pastebin.com/mGEp6vjV
>>> btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
>>> btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
>>>
>>> can't mount the partition with
>>> BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
>>
>> Something wiped your fs on-disk data.
>> And the wiped one belongs to one of the most essential tree, chunk tree.
>>
>> What's the history of the fs?
>> It doesn't look like a bug in btrfs, but some external thing wiped it.
>>
>> Thanks,
>> Qu
>>
>>> [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
>>> [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
>>>
>>


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Re: fix for ERROR: cannot read chunk root

[Sergiu Cozma]

Well nothing to lose now so if you come up with any exotic ideas you
wanna try please let me know, I will keep the partition for the next
couple of days.

Thank you for your time.

On Thu, Nov 7, 2019 at 2:44 AM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>
>
>
> On 2019/11/6 下午11:52, Sergiu Cozma wrote:
> > Hi, thanks for taking the time to help me out with this.
> >
> > The history is kinda bad, I tried to resize the partition but gparted
> > failed saying that the the fs has errors and after throwing some
> > commands found on the internet at it now I'm here :(
>
> Not sure how gparted handle resize, but I guess it should use
> btrfs-progs to do the resize?
>
> >
> > Any chance to recover or rebuild the chunk tree?
>
> I don't think so. Since it's wiped, there is no guarantee that only
> chunk tree is wiped.
>
> THanks,
> Qu
>
>
> >
> >
> > On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
> >>
> >>
> >>
> >> On 2019/11/5 下午11:04, Sergiu Cozma wrote:
> >>> hi, i need some help to recover a btrfs partition
> >>> i use btrfs-progs v5.3.1
> >>>
> >>> btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> >>> btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> >>> btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
> >>>
> >>> can't mount the partition with
> >>> BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
> >>
> >> Something wiped your fs on-disk data.
> >> And the wiped one belongs to one of the most essential tree, chunk tree.
> >>
> >> What's the history of the fs?
> >> It doesn't look like a bug in btrfs, but some external thing wiped it.
> >>
> >> Thanks,
> >> Qu
> >>
> >>> [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> >>> [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
> >>>
> >>
>

Re: fix for ERROR: cannot read chunk root

[Sergiu Cozma]

root   856153161728
chunk_root     856119312384

Aren't those nr too high for a 416GB partition?

On Thu, Nov 7, 2019 at 9:16 AM Sergiu Cozma <lssjbrolli@gmail.com> wrote:
>
> Well nothing to lose now so if you come up with any exotic ideas you
> wanna try please let me know, I will keep the partition for the next
> couple of days.
>
> Thank you for your time.
>
> On Thu, Nov 7, 2019 at 2:44 AM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
> >
> >
> >
> > On 2019/11/6 下午11:52, Sergiu Cozma wrote:
> > > Hi, thanks for taking the time to help me out with this.
> > >
> > > The history is kinda bad, I tried to resize the partition but gparted
> > > failed saying that the the fs has errors and after throwing some
> > > commands found on the internet at it now I'm here :(
> >
> > Not sure how gparted handle resize, but I guess it should use
> > btrfs-progs to do the resize?
> >
> > >
> > > Any chance to recover or rebuild the chunk tree?
> >
> > I don't think so. Since it's wiped, there is no guarantee that only
> > chunk tree is wiped.
> >
> > THanks,
> > Qu
> >
> >
> > >
> > >
> > > On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
> > >>
> > >>
> > >>
> > >> On 2019/11/5 下午11:04, Sergiu Cozma wrote:
> > >>> hi, i need some help to recover a btrfs partition
> > >>> i use btrfs-progs v5.3.1
> > >>>
> > >>> btrfs rescue super-recover https://pastebin.com/mGEp6vjV
> > >>> btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
> > >>> btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
> > >>>
> > >>> can't mount the partition with
> > >>> BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
> > >>
> > >> Something wiped your fs on-disk data.
> > >> And the wiped one belongs to one of the most essential tree, chunk tree.
> > >>
> > >> What's the history of the fs?
> > >> It doesn't look like a bug in btrfs, but some external thing wiped it.
> > >>
> > >> Thanks,
> > >> Qu
> > >>
> > >>> [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
> > >>> [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
> > >>>
> > >>
> >

Re: fix for ERROR: cannot read chunk root

[Qu Wenruo]

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On 2019/11/10 下午11:40, Sergiu Cozma wrote:
> root   856153161728
> chunk_root     856119312384
> 
> Aren't those nr too high for a 416GB partition?

It's btrfs logical address, they can be any aligned numbers in the range
of (0, U64-1).

So no problem at all.

Just check this:
# mkfs.btrfs -f -b 1G $dev
# mount $dev $mnt
# for i in $(seq 5); do
    btrfs balance --full $mnt
$ btrfs ins dump-super /dev/nvme/btrfs | grep chunk_root
chunk_root_generation   132
chunk_root              2018525184  << Way beyond 1G.
chunk_root_level        0


According to "have 0" errors, they are wiped somehow, and it's not
caused by btrfs kernel module.

Thanks,
Qu

> 
> On Thu, Nov 7, 2019 at 9:16 AM Sergiu Cozma <lssjbrolli@gmail.com> wrote:
>>
>> Well nothing to lose now so if you come up with any exotic ideas you
>> wanna try please let me know, I will keep the partition for the next
>> couple of days.
>>
>> Thank you for your time.
>>
>> On Thu, Nov 7, 2019 at 2:44 AM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>>
>>>
>>>
>>> On 2019/11/6 下午11:52, Sergiu Cozma wrote:
>>>> Hi, thanks for taking the time to help me out with this.
>>>>
>>>> The history is kinda bad, I tried to resize the partition but gparted
>>>> failed saying that the the fs has errors and after throwing some
>>>> commands found on the internet at it now I'm here :(
>>>
>>> Not sure how gparted handle resize, but I guess it should use
>>> btrfs-progs to do the resize?
>>>
>>>>
>>>> Any chance to recover or rebuild the chunk tree?
>>>
>>> I don't think so. Since it's wiped, there is no guarantee that only
>>> chunk tree is wiped.
>>>
>>> THanks,
>>> Qu
>>>
>>>
>>>>
>>>>
>>>> On Wed, Nov 6, 2019, 13:34 Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 2019/11/5 下午11:04, Sergiu Cozma wrote:
>>>>>> hi, i need some help to recover a btrfs partition
>>>>>> i use btrfs-progs v5.3.1
>>>>>>
>>>>>> btrfs rescue super-recover https://pastebin.com/mGEp6vjV
>>>>>> btrfs inspect-internal dump-super -a https://pastebin.com/S4WrPQm1
>>>>>> btrfs inspect-internal dump-tree https://pastebin.com/yX1zUDxa
>>>>>>
>>>>>> can't mount the partition with
>>>>>> BTRFS error (device sdb4): bad tree block start, want 856119312384 have 0
>>>>>
>>>>> Something wiped your fs on-disk data.
>>>>> And the wiped one belongs to one of the most essential tree, chunk tree.
>>>>>
>>>>> What's the history of the fs?
>>>>> It doesn't look like a bug in btrfs, but some external thing wiped it.
>>>>>
>>>>> Thanks,
>>>>> Qu
>>>>>
>>>>>> [ 2295.237145] BTRFS error (device sdb4): failed to read chunk root
>>>>>> [ 2295.301067] BTRFS error (device sdb4): open_ctree failed
>>>>>>
>>>>>
>>>


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