[$] BPF meets io_uring

Over the last couple of years, a lot of development effort has gone intotwo kernel subsystems:BPF andio_uring. The BPF virtual machine allowsprograms from user space to be safely run within the context of the kernel,while io_uring addresses the longstanding problem of running system callsasynchronously. As the two subsystems expand, it was inevitable that thetwo would eventually meet; the first encounter happened in mid-Februarywith this patchset from Pavel Begunkov adding the ability to run BPF programs fromwithin io_uring.