Re: [PATCH 0/3] btrfs-progs: Add check and repair for invalid inode generation

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

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On 2019/10/20 上午12:24, Ferry Toth wrote:
> Hi,
> 
> Op 19-10-2019 om 01:50 schreef Qu WenRuo:
>>
>>
>> On 2019/10/19 上午4:32, Ferry Toth wrote:
>>> Op 24-09-2019 om 10:11 schreef Qu Wenruo:
>>>> We have at least two user reports about bad inode generation makes
>>>> kernel reject the fs.
>>>
>>> May I add my report? I just upgraded Ubuntu from 19.04 -> 19.10 so
>>> kernel went from 5.0 -> 5.3 (but I was using 4.15 too).
>>>
>>> Booting 5.3 leaves me in initramfs as I have /boot on @boot and / on /@
>>>
>>> In initramfs I can try to mount but get something like
>>> btrfs critical corrupt leaf invalid inode generation open_ctree failed
>>>
>>> Booting old kernel works just as before, no errors.
>>>
>>>> According to the creation time, the inode is created by some 2014
>>>> kernel.
>>>
>>> How do I get the creation time?
>>
>> # btrfs ins dump-tree -b <the bytenr reported by kernel> <your device>
> 
> I just went back to the office to reboot to 5.3 and check the creation
> times and found they were 2013 - 2014.
> 
>>>
>>>> And the generation member of INODE_ITEM is not updated (unlike the
>>>> transid member) so the error persists until latest tree-checker
>>>> detects.
>>>>
>>>> Even the situation can be fixed by reverting back to older kernel and
>>>> copying the offending dir/file to another inode and delete the
>>>> offending
>>>> one, it still should be done by btrfs-progs.
>>>>
>>> How to find the offending dir/file from the command line manually?
>>
>> # find <mount point> -inum <inode number>
> 
> This works, thanks.
> 
> But appears unpractical. After fix 2 files and reboot, I found 4 more,
> then 16, then I gave up.
> 
>> Thanks,
>> Qu
>>
>>>
>>>> This patchset adds such check and repair ability to btrfs-check, with a
>>>> simple test image.
>>>>
>>>> Qu Wenruo (3):
>>>>     btrfs-progs: check/lowmem: Add check and repair for invalid inode
>>>>       generation
>>>>     btrfs-progs: check/original: Add check and repair for invalid inode
>>>>       generation
>>>>     btrfs-progs: fsck-tests: Add test image for invalid inode
>>>> generation
>>>>       repair
>>>>
>>>>    check/main.c                                  |  50 +++++++++++-
>>>>    check/mode-lowmem.c                           |  76
>>>> ++++++++++++++++++
>>>>    check/mode-original.h                         |   1 +
>>>>    .../.lowmem_repairable                        |   0
>>>>    .../bad_inode_geneartion.img.xz               | Bin 0 -> 2012 bytes
>>>>    5 files changed, 126 insertions(+), 1 deletion(-)
>>>>    create mode 100644
>>>> tests/fsck-tests/043-bad-inode-generation/.lowmem_repairable
>>>>    create mode 100644
>>>> tests/fsck-tests/043-bad-inode-generation/bad_inode_geneartion.img.xz
>>>>
>>>
> 
> I checked out and built v5.3-rc1 of btrfs-progs. Then ran it on my
> mounted rootfs with linux 5.0 and captured the log (~1800 lines 209
> errors).

It's really not recommended to run btrfs check, especially repair on the
mounted fs, unless it's RO.

A new transaction from kernel can easily screw up the repaired fs.
> 
> I'm not sure if using the v5.0 kernel and/or checking mounted distorts
> the results? Else I'm going to need a live usb with a v5.3 kernel and
> v5.3 btrfs-progs.
> 
> If you like I can share the log. Let me know.
> 
> This issue can potentially cause a lot of grief. Our company server runs
> Ubuntu LTS (18.04.02) with a 4.15 kernel on a btrfs boot/rootfs with
> ~100 snapshots. I guess the problematic inodes need to be fixed on each
> snapshot prior to upgrading to 20.04 LTS (which might be on kernel ~5.6)?

Yes.

> 
> Do I understand correctly that this FTB is caused by more strict
> checking of the fs by the kernel, while the tools to fix the detected
> corruptions are not yet released?

Yes.

Thanks,
Qu


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