Re: 'btrfs rescue' command (recommended by btrfs check) fails on old BTRFS RAID1 on (currently) openSUSE Leap 15.3

[Johannes Kastl <kastl@b1-systems.de>]

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Hi Qu,

On 24.04.22 at 01:07 Qu Wenruo wrote:

> No need to run btrfs check on each device.
> 
> Btrfs check will assemble the array automatically (just like kernel),
> and check the fs on all involved devices.
> Thus no need to run the same check on all devices.

OK, good to know. That saves half the time :-)

>> The output of the check is below. The TL;DR was that I should run 'btrfs
>> rescue fix-device-size' to fix a "minor" issue.
>>
>> Unfortunately, running this command fails:
>>
>>> root dumbo:/root # btrfs rescue fix-device-size /dev/sdc1
>>> Unable to find block group for 0
>>> Unable to find block group for 0
>>> Unable to find block group for 0
> 
> This is an unique error message, which can only be triggered when
> btrfs-progs failed to find a block group with enough free space.

So would resizing the filesystem (to 8GiB) workaround this "limitation", so 
afterwards it could properly fix the device size?

>>> btrfs unable to find ref byte nr 2959295381504 parent 0 root 3  owner
>>> 1 offset 0
>>> transaction.c:168: btrfs_commit_transaction: BUG_ON `ret` triggered,
>>> value -5
> 
> So at least no damage done to the good and innocent (but a little old) fs.

Puuuh, nice to hear that. :-)

>> So, my question is what I should do:
>>
>> Do I need to run another command to fix this issue?
> 
> Not really.
> 
> But if you want to really remove the warning, please update btrfs-progs
> first, to the latest stable version (v5.16.2), and try again.

I'll have a look if I can easily install a newer version of btrfsprogs on this 
machine.

> The involved progs, v4.19 is a little old, and IIRC we had some ENOSPC
> related fixed in progs, thus if above problem a bug caused false ENOSPC,
> it should be fixed now.

If I can install a newer version, I'll let you know if the bug disappears.

> You can ignore it for now.
> It's not a big deal and kernel can handle it without problem.

That's good.

>> Should I copy all of the data to another disk, and create a new BTRFS
>> RAID1 from scratch? (Which of course I would like to avoid, if possible...)
> 
> Definitely no.

Perfect.

Thanks for your reply! Have a nice day.

Kind Regards,
Johannes

-- 
Johannes Kastl
Linux Consultant & Trainer
Tel.: +49 (0) 151 2372 5802
Mail: kastl@b1-systems.de

B1 Systems GmbH
Osterfeldstraße 7 / 85088 Vohburg
http://www.b1-systems.de
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