Remove stale qgroup entires when incrementally backing up a btrfs partition to an external hdd

Question

This is the procedure that I am currently using to incrementally backup my btrfs partition to an external drive. The issue im having is that the qgroup is still showing the deleted subvolume even after I run rescan (btrfs quota rescan /media/BTRFS).

Move the backup to backup-old on both the BTRFS and the ext hdd

mv /media/BTRFS/BTRFS-RO /media/BTRFS/BTRFS-RO-OLD
mv /media/EXT_BACKUP_DRIVE/BTRFS-RO /media/EXT_BACKUP_DRIVE/BTRFS-RO-OLD

Create a new read-only snapshot

btrfs su sn -r /media/BTRFS /media/BTRFS/BTRFS-RO

Sync the changes

sync

Send the changes to the external drive

btrfs send -p /media/BTRFS/BTRFS-RO-OLD /media/BTRFS/BTRFS-RO | btrfs receive /media/EXT_BACKUP_DRIVE

Delete the old (no longer needed subvolume)

btrfs subvolume delete /media/BTRFS/BTRFS-RO-OLD
btrfs subvolume delete /media/EXT_BACKUP_DRIVE/BTRFS-RO-OLD

This is the subvoume list before delete

btrfs subvolume list /media/BTRFS ID 257 gen 61392 top level 5 path BigDrive ID 7146 gen 38871 top level 257 path BTRFS-RO-OLD ID 7231 gen 60344 top level 257 path BTRFS-RO

qgroupid         rfer         excl
--------         ----         ----
0/5          16.00KiB     16.00KiB
0/257         4.81TiB      1.49GiB
0/7146        4.73TiB      9.63GiB
0/7230       64.00KiB     16.00EiB
0/7231        4.81TiB     22.46MiB

and after delete

btrfs subvolume list /media/BTRFS
ID 257 gen 61418 top level 5 path BigDrive
ID 7231 gen 60344 top level 257 BTRFS-RO

qgroupid         rfer         excl
--------         ----         ----
0/5          16.00KiB     16.00KiB
0/257         4.81TiB      1.49GiB
0/7146       16.00KiB     16.00EiB
0/7230       64.00KiB     16.00EiB
0/7231        4.81TiB     22.48MiB

Answer 1

Looks like I found the answer by:

btrfs qgroup destroy 0/7146 /media/BTRFS

Would this have any negative consequences for the data?