How to stop QEMU punching holes in backing store

[Justin]

Hi. I'm using QEMU emulator version 5.2.0 on Linux. I am using
thick-provisioned RAW files as the VM backing store. I've found that
QEMU is punching holes in my RAW files, which I don't want it to do.

I've run strace and I see calls to fallocate with these flags:
FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE

I've tried passing these options: discard=off,detect-zeroes=off but
this does not help. This is the full set of relevant options I'm
using:

-drive file=/vms/vm0/drive,format=raw,if=virtio,discard=off,detect-zeroes=off

How do I completely disable all hole punching?