Re: btrfs send and receive showing errors

["Randy Nürnberger" <ranuberger@posteo.de>]

On Thu, Jan 5, 2023 at 11:42, Filipe Manana wrote:
> On Thu, Jan 5, 2023 at 10:10 AM Randy Nürnberger <ranuberger@posteo.de> wrote:
>> On Wed, Jan 4, 2023 at 14:41, Filipe Manana wrote:
>>> On Wed, Jan 4, 2023 at 1:05 PM Randy Nürnberger <ranuberger@posteo.de> wrote:
>>>> Hello,
>>>>
>>>> I’m in the process of copying a btrfs filesystem (a couple years old)
>>>> from one disk to another by using btrfs send and receive on all
>>>> snapshots. The snapshots were created by a tool every hour on the hour
>>>> as one backup measure and automatically removed as they became older.
>>>>
>>>> I got errors like the following and when I compare the copied snapshots
>>>> with the originals, some files are missing:
>>>>
>>>> ERROR: unlink █████ failed: No such file or directory
>>>> ERROR: link █████ -> █████ failed: No such file or directory
>>>> ERROR: utimes █████ failed: No such file or directory
>>>> ERROR: rmdir █████ failed: No such file or directory
>>>>
>>>> Is this a known bug and how can I help diagnosing and fixing this?
>>> So this is a problem caused by the sender issuing commands with outdated paths.
>>>
>>> First, try doing the send operation again with a 6.1 kernel - there
>>> was at least one fix here that may be relevant.
>> I tried again with the following kernel version and still got the same
>> errors:
>> Linux arktos 6.1.0-0-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.2-1~exp1
>> (2023-01-01) x86_64 GNU/Linux
>>
>>> To actual debug things, in case it's not working with 6.1:
>>>
>>> 1) Show how you invoked send and receive. I.e. the full command lines
>>> for 'btrfs send ...' and 'btrfs receive ...'
>> Those are my full command lines:
>>
>> btrfs send -p /mnt/randy/randy-snapshots/2022-01-29--07-00
>> /mnt/randy/randy-snapshots/2022-02-27--10-00 | btrfs receive -vvv
>> /mnt/intern/randy-snapshots/ 2>receive-1.txt
>>
>> btrfs send -p /mnt/randy/randy-snapshots/2022-02-27--10-00
>> /mnt/randy/randy-snapshots/2022-03-26--07-00 | btrfs receive -vvv
>> /mnt/intern/randy-snapshots/ 2>receive-2.txt
>>
>>> 2) Provide the whole output of 'btrfs receive' with the -vvv command
>>> line option.
>>>       This will reveal all path names, but it's necessary to debug things.
>>>       You've hidden path names above, so I suppose that's not acceptable for you.
>> At least I’m not comfortable sharing the file names on this public
>> mailing list. I carefully tried to extract and redact what may be the
>> relevant parts.
>>
>> The second command line above is the first one that fails with the
>> following error: “ERROR: unlink Hase/Fuchs/2022-02-23 Reh.odt failed: No
>> such file or directory”.
>>
>> This is the directory listing for the snapshot before said file was
>> created (this snapshot can be copied without errors):
>>
>> root@arktos /m/r/randy-snapshots# ls -alh 2022-01-29--07-00/Hase/Fuchs/
>> insgesamt 2,6M
>> drwxrws--- 1 randy randy  136 19. Dez 2021   ./
>> drwxrws--- 1 randy randy  134 24. Nov 2021   ../
>> -rw-rw---- 1 randy randy  38K  5. Mai 2021  '2021-05-01 Igel.odt'
>> -rw-rw---- 1 randy randy  16K 30. Sep 2021  '2021-09-30 Wolf.odt'
>> -rw-rw---- 1 randy randy 2,6M 19. Dez 2021  '2021-12-19 Wildschwein.pdf'
>>
>> This is the directory listing for the snapshot after the file has been
>> created (this snapshot can be copied without errors):
>>
>> root@arktos /m/r/randy-snapshots# ls -alh 2022-02-27--10-00/Hase/Fuchs/
>> insgesamt 2,7M
>> drwxrws---  1 randy randy  178 27. Feb 2022   ./
>> drwxrws---  1 randy randy  134 24. Nov 2021   ../
>> -rw-rw----  1 randy randy  38K  5. Mai 2021  '2021-05-01 Igel.odt'
>> -rw-rw----  1 randy randy  16K 30. Sep 2021  '2021-09-30 Wolf.odt'
>> -rw-rw----  1 randy randy 2,6M 19. Dez 2021  '2021-12-19 Wildschwein.pdf'
>> -rw-rwx---+ 1 randy randy  42K 26. Feb 2022  '2022-02-23 Reh.odt'*
>>
>> This is the directory listing for the snapshot after the file has been
>> edited in LibreOffice and *renamed* (trying to copy this one fails):
>>
>> root@arktos /m/r/randy-snapshots# ls -alh 2022-03-26--07-00/Hase/Fuchs/
>> insgesamt 2,6M
>> drwxrws--- 1 randy randy  178  5. Mär 2022   ./
>> drwxrws--- 1 randy randy  134 24. Nov 2021   ../
>> -rw-rw---- 1 randy randy  38K  5. Mai 2021  '2021-05-01 Igel.odt'
>> -rw-rw---- 1 randy randy  16K 30. Sep 2021  '2021-09-30 Wolf.odt'
>> -rw-rw---- 1 randy randy 2,6M 19. Dez 2021  '2021-12-19 Wildschwein.pdf'
>> -rw-rw---- 1 randy randy  18K  4. Mär 2022  '2022-03-03 Reh.odt'
>>
>> I’ve attached the outputs of the commands above. Apparently ‘btrfs send’
>> instructs ‘btrfs receive’ to unlink the file ‘Hase/Fuchs/2022-02-23
>> Reh.odt’ which *does* exist in the copied snapshot ‘2022-02-27--10-00’
>> and this fails for whatever reason.
> The reason is very likely because the file was renamed, but the unlink
> operation is using the old name (pre-rename name), instead of the new
> name.
>
> For the second receive, there should be other operations affecting the
> file path Hase/Fuchs/2022-02-23 Reh.odt:

Unfortunately, there are not.

I’m not sure how LibreOffice saves files, but it may create a new file 
and then replace the old one, so the unlink of the old file name can 
make sense, I think.

When I compare the two copied snapshots, the file is indeed gone, so the 
unlink operation actually seems to have worked?

root@arktos /m/i/randy-snapshots# ls -alh 2022-02-27--10-00/Hase/Fuchs/
insgesamt 2,7M
drwxrws---  1 randy randy  178 27. Feb 2022   ./
drwxrws---  1 randy randy  134 24. Nov 2021   ../
-rw-rw----  1 randy randy  38K  5. Mai 2021  '2021-05-01 Igel.odt'
-rw-rw----  1 randy randy  16K 30. Sep 2021  '2021-09-30 Wolf.odt'
-rw-rw----  1 randy randy 2,6M 19. Dez 2021  '2021-12-19 Wildschwein.pdf'
-rw-rwx---+ 1 randy randy  42K 26. Feb 2022  '2022-02-23 Reh.odt'*

root@arktos /m/i/randy-snapshots# ls -alh 2022-03-26--07-00/Hase/Fuchs/
insgesamt 2,6M
drwxrws--- 1 randy randy  136  5. Mär 2022   ./
drwxrws--- 1 randy randy  134 24. Nov 2021   ../
-rw-rw---- 1 randy randy  38K  5. Mai 2021  '2021-05-01 Igel.odt'
-rw-rw---- 1 randy randy  16K 30. Sep 2021  '2021-09-30 Wolf.odt'
-rw-rw---- 1 randy randy 2,6M 19. Dez 2021  '2021-12-19 Wildschwein.pdf'

I also just compiled btrfs-progs v6.1.1 and tried those and still got 
the same error.

>
> utimes Hase/Fuchs
> […]
> unlink Hase/Fuchs/2022-02-23 Reh.odt
> ERROR: unlink Hase/Fuchs/2022-02-23 Reh.odt failed: No such file or directory
>
> Somewhere in the [...] there must be at least one rename of
> Hase/Fuchs/2022-02-23 Reh.odt into something else.
> It would be interesting to see more of the receive log to determine if
> and why that rename happened.
>
> If this is blocking you right now, you can do a full send of the
> snapshot at /mnt/randy/randy-snapshots/2022-03-26--07-00.
> That will, almost certainly, succeed. Though it will be slower.

Thanks, I’m just copying my filesystem onto bigger disks and that can 
wait some time.

>
> Thanks.
>
>
>> # sha256sum
>> /mnt/randy/randy-snapshots/2022-02-27--10-00/Hase/Fuchs/2022-02-23\ Reh.odt
>> 09ab560f8e2d79e61d253550eda5f388aceddb1b51792e01e589e86a53cdd226
>>
>> # sha256sum
>> /mnt/intern/randy-snapshots/2022-02-27--10-00/Hase/Fuchs/2022-02-23\
>> Reh.odt
>> 09ab560f8e2d79e61d253550eda5f388aceddb1b51792e01e589e86a53cdd226
>>
>>> Thanks.
>>>
>>>> # uname -a  # this is the kernel on which this originally happend
>>>> Linux arktos 5.10.0-20-amd64 #1 SMP Debian 5.10.158-2 (2022-12-13)
>>>> x86_64 GNU/Linux
>>>>
>>>>
>>>> # uname -a  # I already retried everything on the latest Debian
>>>> backports kernel with the same results
>>>> Linux arktos 6.0.0-0.deb11.6-amd64 #1 SMP PREEMPT_DYNAMIC Debian
>>>> 6.0.12-1~bpo11+1 (2022-12-19) x86_64 GNU/Linux
>>>>
>>>> # btrfs --version
>>>> btrfs-progs v5.10.1
>>>>
>>>> # btrfs fi sh /mnt/randy  # this is the source
>>>> Label: none  uuid: 84bba855-578d-48db-80eb-49f1029c7543
>>>>            Total devices 2 FS bytes used 2.04TiB
>>>>            devid    1 size 4.00TiB used 2.05TiB path /dev/mapper/randy_1_crypt
>>>>            devid    2 size 4.00TiB used 2.05TiB path /dev/mapper/randy_2_crypt
>>>>
>>>> # btrfs fi df /mnt/randy
>>>> Data, RAID1: total=2.02TiB, used=2.02TiB
>>>> System, RAID1: total=8.00MiB, used=320.00KiB
>>>> Metadata, RAID1: total=25.00GiB, used=22.99GiB
>>>> GlobalReserve, single: total=512.00MiB, used=0.00B
>>>>
>>>>
>>>> # btrfs fi sh /mnt/intern  # this is the target
>>>> Label: none  uuid: ebb94498-644c-42cd-892f-37886173523c
>>>>            Total devices 2 FS bytes used 1.91TiB
>>>>            devid    1 size 8.00TiB used 1.91TiB path
>>>> /dev/mapper/vg_arktos_hdd_b-lv_randy_1
>>>>            devid    2 size 8.00TiB used 1.91TiB path
>>>> /dev/mapper/vg_arktos_hdd_b-lv_randy_2
>>>>
>>>> # btrfs fi df /mnt/intern
>>>> Data, RAID1: total=1.89TiB, used=1.89TiB
>>>> System, RAID1: total=8.00MiB, used=288.00KiB
>>>> Metadata, RAID1: total=21.00GiB, used=20.76GiB
>>>> GlobalReserve, single: total=512.00MiB, used=0.00B