Re: BTRFS error (device sda4): failed to read chunk tree: -5

[Zirconium Hacker <jared.e.vb@gmail.com>]

I already ran that earlier, here's the pastebin: https://pastebin.com/KGB8nVRA

Running debug-tree on all 1084 of them (I guess that was unnecessary)
gave the same errors every time:
bytenr mismatch, want=61809344512, have=0
Couldn't read tree root
ERROR: unable to open /dev/sda4

On Fri, Aug 18, 2017 at 5:03 AM, Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>
>
> On 2017年08月18日 16:47, Zirconium Hacker wrote:
>>
>> $ sudo btrfs-debug-tree -b 131072 /dev/sda4
>> btrfs-progs v4.12
>> bytenr mismatch, want=61809344512, have=0
>> Couldn't read tree root
>> ERROR: unable to open /dev/sda4
>
>
> I think this can be improved for case like this.
> I'll try to submit a patch to enhance btrfs-debug-tree.
>
> Would you please try "btrfs-find-root /dev/sda4"?
> This will try to locate on-disk old tree root, and if we're lucky, old tree
> root can allow us to mount the fs.
>
>>
>> Mounting with degraded,ro does not fix the multi-device issue.  The
>> system was never really intended to have a second device, though:
>
>
> Wait for a minute, did you mean this btrfs doesn't ever have a second
> device?
> This seems quite weird now.
>
>>
>> $ sudo btrfs fi show /dev/sda4
>> bytenr mismatch, want=61809344512, have=0
>> Couldn't read tree root
>> Label: none  uuid: 29889b3a-1c10-48e4-ad6d-21d03d06e90b
>> Total devices 2 FS bytes used 49.52GiB
>> devid    1 size 54.07GiB used 54.07GiB path /dev/sda4
>> *** Some devices missing
>>
>> I vaguely remember following this guide at some point:
>>
>> http://marc.merlins.org/perso/btrfs/post_2014-05-04_Fixing-Btrfs-Filesystem-Full-Problems.html
>> -- specifically the "Balance cannot run because the filesystem is
>> full" part.  This may have broken some things?
>
>
> Not sure, at least from your superblock, too many things are in doubt.
> From the number of devices, to strange system chunk.
>
>
> Thanks,
> Qu
>>
>>
>> On Fri, Aug 18, 2017 at 4:15 AM, Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>>
>>>
>>>
>>> On 2017年08月18日 15:17, Zirconium Hacker wrote:
>>>>
>>>>
>>>> I checked my fstab, and my mount options for that partition are:
>>>> nodev,nosuid (so no discard).
>>>> As far as I remember, I had some issues converting from ext4 with
>>>> existing tools (I think that was on Debian so the tools were likely
>>>> older) so I did a manual conversion backup, wipe, copy files back).
>>>>
>>>> $ sudo btrfs-find-root -o 3 /dev/sda4
>>>> Couldn't read tree root
>>>> Superblock thinks the generation is 311252
>>>> Superblock thinks the level is 0
>>>> ERROR: tree block bytenr 0 is not aligned to sectorsize 4096
>>>> Found tree root at 131072 gen 311252 level 0
>>>
>>>
>>>
>>> So chunk root (and since it's level 0, the whole chunk tree) seems good.
>>>
>>> Could you please try the following command?
>>> # btrfs-debug-tree -b 131072 /dev/sda4
>>>
>>> I assume it may fail due to the fact that root tree is corrupted.
>>> But maybe we are lucky?
>>>
>>>
>>> And further investigating your super dump and the code, it's shows some
>>> clue, mostly related to your multi-device setup.
>>>
>>> Your find-root output shows that, the only chunk leaf in /dev/sda4 seems
>>> good.
>>> And in btrfs_read_chunk_tree(), which returned -EIO and caused the error
>>> message, will first search chunk root.
>>>
>>> Since your chunk leaf is good, such search itself should not cause too
>>> much
>>> problem.
>>>
>>> Then btrfs_read_chunk_tree() will try to read out each device, by calling
>>> read_one_dev().
>>> Which can return -EIO if any device is missing and you're not using
>>> degraded
>>> mount option.
>>>
>>> Is your 2nd device missing? If so, would you please try to mount with
>>> "degraded,ro" mount option?
>>>
>>> BTW, if you didn't manually convert chunk profiles, did you first create
>>> btrfs on single device, and then added a new device to the btrfs?
>>>
>>> Thanks,
>>> Qu
>>>
>>>>
>>>> On Fri, Aug 18, 2017 at 12:10 AM, Chris Murphy <lists@colorremedies.com>
>>>> wrote:
>>>>>
>>>>>
>>>>> On Thu, Aug 17, 2017 at 4:42 PM, Qu Wenruo <quwenruo.btrfs@gmx.com>
>>>>> wrote:
>>>>>
>>>>>> BTW are you using discard mount option? Sometimes it can cause
>>>>>> problem.
>>>>>
>>>>>
>>>>>
>>>>> OP did not say if it was using discard mount option; but did say some
>>>>> time before this (I'm not sure how recent) he had used fstrim. The
>>>>> firmware for this SSD model is current.
>>>>>
>>>>>
>>>>> --
>>>>> Chris Murphy
>>>>
>>>>
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>>>>
>>>
>