The io_uring subsystem has, in the last
year, redefined how asynchronous I/O is done on Linux systems. As this
subsystem grows in both capability and users, though, it starts to run into
limitations in the types of operations that can be expressed. That is
driving a number of changes in how operations are programmed for io_uring.
One example is the mechanisms considered for carrying a file descriptor
between operations that was covered here in early March. Another has to
do with how I/O buffers are chosen for operations.

Source: LWN.net – [$] Automatic buffer selection for io_uring