hi.
it might help:
https://forum.qubes-os.org/t/simple-config-for-faster-storage-for-disk-write-intensive-building-environment-via-btrfs-volumes/13616
edit: hum, maybe not, indeed, we just got dom0:dm-NN as well.
didn’t tried, but without the ENV{UDEV_DISABLE_PERSISTENT_STORAGE_RULES_FLAG}="1",
you could try with qvm-block attach --persistent