apt-btrfs-snapshot doesn't support my system, even though my root partition is Btrfs

[YamiYukiSenpai]

> sudo apt-btrfs-snapshot --debug
The system does not support apt-btrfs-snapshot

## Root partition
> blkid | grep -i Tuxedo
/dev/nvme0n1p2: LABEL="Tuxedo" UUID="4777728a-1d39-4af3-aeca-4fdf5a3d6cf0" UUID_SUB="34bee598-a820-4335-b372-f99862461189" BLOCK_SIZE="4096" TYPE="btrfs" PARTUUID="5403ca92-4062-934c-8e52-5a225b593790"

 

My root partition is on Btrfs, and the root itself is in the `@` subvolume.

 

Here's the list of subvolumes on my primary SSD:

> ls -l /mnt/tmp/
total 32
drwxr-xr-x 1 root   1001  256 Oct 15 01:37 @
drwxr-xr-x 1 root root     24 Sep 21 11:09 @home
drwxrwxr-x 1 root syslog  916 Nov  4 00:00 @logs
drwxr-xr-x 1 root root   1184 Oct 31 03:15 @snap
drwxr-xr-x 1 root root      0 Oct  7 23:21 @snapshots
drwxr-xr-x 1 root root     16 Oct  7 23:34 @swap
drwxr-xr-x 1 root root    210 Oct  8 00:18 timeshift-btrfs
drwxrwxrwt 1 root root   1398 Nov  4 01:02 @tmp
drwxr-xr-x 1 root root    386 Nov  3 20:14 @var-lib-snapd
drwxr-xr-x 1 root root   1166 Oct 31 03:15 @var-snap

 

I can't figure out what that missing piece is.

 

Operating System: TUXEDO OS 3
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.6.0
Qt Version: 6.7.2
Kernel Version: 6.11.0-103009-tuxedo (64-bit)
Graphics Platform: Wayland
Processors: 24 × AMD Ryzen 9 5900X 12-Core Processor
Memory: 62.7 GiB of RAM
Graphics Processor: AMD Radeon RX 6900 XT
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: X570S AORUS MASTER
System Version: -CF

[YamiYukiSenpai]

SOLVED

 

I found the reason:

UUID=5478d0cc-e982-4347-a7e1-040d1c432850 /                     btrfs   subvol=@,space_cache=v2,compress=zstd:3,defaults        0 1

By default (and originally), the option is subvol=/@. Changing it to subvol=@ solved it!

This pointed me to the cause in /usr/lib/python3/dist-packages/apt_btrfs_snapshot.py:

    def _get_supported_btrfs_root_fstab_entry(self):
        """ return the supported btrfs root FstabEntry or None """
        for entry in self.fstab:
            if (
                    entry.mountpoint == "/" and
                    entry.fstype == "btrfs" and
                    "subvol=@" in entry.options):
                return entry
        return None