Outreachy project task: Adding QEMU block layer APIs resembling Linux ZBD ioctls.

[Sam Li]

Hi everyone,
I'm Sam Li, working on the Outreachy project which is to add zoned
device support to QEMU's virtio-blk emulation.

For the first goal, adding QEMU block layer APIs resembling Linux ZBD
ioctls, I think the naive approach would be to introduce a new stable
struct zbd_zone descriptor for the library function interface. More
specifically, what I'd like to add to the BlockDriver struct are:
1. zbd_info as zone block device information: includes numbers of
zones, size of logical blocks, and physical blocks.
2. zbd_zone_type and zbd_zone_state
3. zbd_dev_model: host-managed zbd, host-aware zbd
With those basic structs, we can start to implement new functions as
bdrv*() APIs for BLOCK*ZONE ioctls.

I'll start to finish this task based on the above description. If
there is any problem or something I may miss in the design, please let
me know.

Best regards,
Sam