Hello. I'm currently working on improving disko's support for bcachefs. So far, I have made a PR to add encryption support. Currently, I am working on adding subvolume support. However, I am having trouble getting this to work. This is the output when I run nix build --no-link .#checks.x86_64-linux.bcachefs-subvolumes --show-trace -L -v.

I suspect that a reason that this could happening might be due the order in which mountpoints are mounted. My theory is that descendant mountpoints (e.g., /ancestor/descendant) could be being mounted before ancestor mountpoints (e.g., /ancestor) have been created/mounted.

Does disko mount filesystems such that ancestor mountpoints are mounted before descendants, or is this behaviour dependent on how the _mount option (made with diskoLib.mkMountOption) for the relevant filesystem type is implemented?

I have tried to debug my implementation using nix build .#checks.x86_64-linux.bcachefs-subvolumes.driverInteractive; result/bin/nixos-test-driver --keep-vm-state, but this doesn't seem to be working properly, as it doesn't show the bcachefs filesystem that should have been created:

$ lsblk -f
NAME FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
fd0                                                                         
sr0                                                                         
vda  ext4   1.0   nixos a7ac900e-9d30-45da-b745-56d7d190aedd  888.3M     2% /
vdb  

In fact, it shows that same lsblk output for various other examples I tried it with (I also tried it with btrfs-subvolumes and simple-efi).

Is there another way I can go about debugging this?