Re: Backup failing with "failed to clone extents" error

[Filipe Manana <fdmanana@gmail.com>]

On Thu, Apr 16, 2020 at 2:16 AM Matt Huszagh <huszaghmatt@gmail.com> wrote:
>
> I'm attempting to perform a backup to an external hard drive. Both the
> native drive and external drive use a BTRFS filesystem. I do this by
> first creating a read-only snapshot of my home directory:
>
> # btrfs subvolume snapshot -r /home /.snapshots/home/BACKUP
>
> Followed by a send/receive to the backup drive:
>
> # btrfs send /.snapshots/home/BACKUP | btrfs receive /.backup/home
>
> I get this output:
>
> At subvol /.snapshots/home/BACKUP
> At subvol BACKUP
> ERROR: failed to clone extents to matt/.local/share/Anki2/Matt/collection.anki2: Invalid argument
>
> There several files that trigger this error (most of them .sqlite
> files). I can delete the offending files, which causes the backup to
> work. However, new offending files are created that recreate the error
> (e.g. Firefox generates lots of offending .sqlite files).
>
> I performed
>
> # btrfs scrub start -B /
>
> which exited without errors and failed to resolve the issue and I even
> ran check --repair on my filesystem unmounted:
>
> # btrfs check --repair /dev/mapper/...
>
> which didn't make a difference.
>
> uname -a:
> Linux ryzen3950 5.5.0 #1-NixOS SMP Mon Jan 27 00:23:03 UTC 2020 x86_64 GNU/Linux

The issue you are hitting is very likely what was fixed by:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9722b10148504c4153a74a9c89725af271e490fc

Upgrade your kernel from 5.5.0 to at least 5.5.3 (latest 5.5 stable
release is 5.5.17).

And rest assured that kind of problem is not because of any
corruption, so need to do a scrub or 'check --repair'.


>
> btrfs --version
> btrfs-progs v5.4.1
>
> btrfs fi show
> Label: 'btrfs'  uuid: d31878d6-3a77-4f0f-9fdd-bb9a2c4e578b
>         Total devices 2 FS bytes used 737.53GiB
>         devid    1 size 931.01GiB used 853.03GiB path /dev/mapper/cryptnvme
>         devid    2 size 931.50GiB used 853.03GiB path /dev/mapper/cryptnvme1
>
> Label: 'backup'  uuid: 0bd10808-0330-4736-9425-059d4a0a300e
>         Total devices 2 FS bytes used 473.34GiB
>         devid    1 size 1.82TiB used 475.01GiB path /dev/mapper/cryptsda1
>         devid    2 size 1.82TiB used 475.01GiB path /dev/mapper/cryptsdb1
>
> btrfs fi df /
> Data, RAID0: total=1.44TiB, used=730.13GiB
> System, RAID1: total=32.00MiB, used=144.00KiB
> Metadata, RAID1: total=20.00GiB, used=7.40GiB
> GlobalReserve, single: total=512.00MiB, used=0.00B
>
> Here's the output of dmesg. I've only taken the lines containing
> dmesg. Please let me know if this is insufficient and I'll provide the
> full log.
>
> [    1.168132] stage-1-init: loading module btrfs...
> [    1.442869] Btrfs loaded, crc32c=crc32c-intel
> [   14.552850] BTRFS: device label backup devid 2 transid 303 /dev/mapper/cryptsdb1 scanned by btrfs (857)
> [   14.553396] BTRFS: device label backup devid 1 transid 303 /dev/mapper/cryptsda1 scanned by btrfs (857)
> [   14.553487] BTRFS: device label btrfs devid 2 transid 409463 /dev/mapper/cryptnvme1 scanned by btrfs (857)
> [   14.553573] BTRFS: device label btrfs devid 1 transid 409463 /dev/mapper/cryptnvme scanned by btrfs (857)
> [   14.553634] stage-1-init: Scanning for Btrfs filesystems
> [   14.561445] BTRFS info (device dm-0): use lzo compression, level 0
> [   14.561447] BTRFS info (device dm-0): enabling ssd optimizations
> [   14.561447] BTRFS info (device dm-0): disk space caching is enabled
> [   14.561448] BTRFS info (device dm-0): has skinny extents
> [   14.637769] BTRFS info (device dm-0): checking UUID tree
> [   14.786327] BTRFS info (device dm-0): disk space caching is enabled
> [   15.926714] BTRFS info (device dm-0): device fsid d31878d6-3a77-4f0f-9fdd-bb9a2c4e578b devid 1 moved old:/dev/mapper/cryptnvme new:/dev/dm-0
> [   15.926763] BTRFS info (device dm-0): device fsid d31878d6-3a77-4f0f-9fdd-bb9a2c4e578b devid 2 moved old:/dev/disk/by-uuid/d31878d6-3a77-4f0f-9fdd-bb9a2c4e578b new:/dev/dm-1
> [   16.043567] BTRFS info (device dm-0): disk space caching is enabled
> [   16.074722] BTRFS info (device dm-2): use lzo compression, level 0
> [   16.074723] BTRFS info (device dm-2): disk space caching is enabled
> [   16.074724] BTRFS info (device dm-2): has skinny extents
> [27057.785935] BTRFS info (device dm-0): scrub: started on devid 1
> [27057.800078] BTRFS info (device dm-0): scrub: started on devid 2
> [27107.287558] BTRFS info (device dm-0): scrub: not finished on devid 1 with status: -125
> [27107.316437] BTRFS info (device dm-0): scrub: not finished on devid 2 with status: -125
> [27109.542589] BTRFS info (device dm-0): scrub: started on devid 1
> [27109.556751] BTRFS info (device dm-0): scrub: started on devid 2
> [27243.975463] BTRFS info (device dm-0): scrub: finished on devid 1 with status: 0
> [27247.857511] BTRFS info (device dm-0): scrub: finished on devid 2 with status: 0
> [250470.993201] [  23284]     0 23284     3204       25    45056        0             0 btrfs
> [250470.993203] [  23286]     0 23286     1155       53    40960        0             0 btrfs
>
> Thanks!
> Matt



-- 
Filipe David Manana,

“Whether you think you can, or you think you can't — you're right.”