Comment # 9 on bug 1174939 from William Brown

Actually, it looks like quota is removed every reboot. So this may be more
major than expected. 

pyrite# snapper ls
   # | Type   | Pre # | Date                             | User | Cleanup |
Description             | Userdata
-----+--------+-------+----------------------------------+------+---------+-------------------------+--------------
  0  | single |       |                                  | root |         |
current                 |
157  | single |       | Wed 12 Aug 2020 01:47:23 AM AEST | root | number  |
Snapshot Update of #156 | important=yes
158  | single |       | Fri 14 Aug 2020 01:45:56 AM AEST | root | number  |
Snapshot Update of #157 | important=yes
...

// change qgroup="" and rescan and wait ...

pyrite# snapper ls
   # | Type   | Pre # | Date                             | User | Used Space |
Cleanup | Description             | Userdata
-----+--------+-------+----------------------------------+------+------------+---------+-------------------------+--------------
  0  | single |       |                                  | root |            | 
       | current                 |
157  | single |       | Wed 12 Aug 2020 01:47:23 AM AEST | root |  48.63 MiB |
number  | Snapshot Update of #156 | important=yes
158  | single |       | Fri 14 Aug 2020 01:45:56 AM AEST | root |   2.37 MiB |
number  | Snapshot Update of #157 | important=yes
...

reboot

pyrite# snapper ls
   # | Type   | Pre # | Date                             | User | Cleanup |
Description             | Userdata
-----+--------+-------+----------------------------------+------+---------+-------------------------+--------------
  0  | single |       |                                  | root |         |
current                 |
157  | single |       | Wed 12 Aug 2020 01:47:23 AM AEST | root | number  |
Snapshot Update of #156 | important=yes
158  | single |       | Fri 14 Aug 2020 01:45:56 AM AEST | root | number  |
Snapshot Update of #157 | important=yes


pyrite# dmesg | grep -i btrf
[    3.640945] Btrfs loaded, crc32c=crc32c-intel, assert=on
[    3.642110] BTRFS: device fsid 1fdd971d-49e8-495f-8bbb-e2b50da2b4bb devid 1
transid 312023 /dev/vda2 scanned by systemd-udevd (292)
[    3.712496] BTRFS info (device vda2): disk space caching is enabled
[    3.712500] BTRFS info (device vda2): has skinny extents
[    4.192751] BTRFS info (device vda2): disk space caching is enabled
[    8.799324] BTRFS info (device vda2): disk space caching is enabled
[   12.765641] BTRFS info (device vda2): disk space caching is enabled
[   62.581588] BTRFS warning (device vda2): qgroup rescan init failed, qgroup
is not enabled