This is an example of using io_uring to copy a file using O_DIRECT and registered buffers like one might do if you were writing a database of some kind.
Creating the initial file. dd if=/dev/zero of=/tmp/stuff bs=4096 count=1024
Tested on
lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.10
Release: 20.10
Codename: groovy