Merge tag 'for-6.15/io_uring-epoll-wait-20250325' of git://git.kernel.dk/linux

Pull io_uring epoll support from Jens Axboe:
 "This adds support for reading epoll events via io_uring.

  While this may seem counter-intuitive (and/or productive), the
  reasoning here is that quite a few existing epoll event loops can
  easily do a partial conversion to a completion based model, but are
  still stuck with one (or few) event types that remain readiness based.

  For that case, they then need to add the io_uring fd to the epoll
  context, and continue to rely on epoll_wait(2) for waiting on events.
  This misses out on the finer grained waiting that io_uring can do, to
  reduce context switches and wait for multiple events in one batch
  reliably.

  With adding support for reaping epoll events via io_uring, the whole
  legacy readiness based event types can still be reaped via epoll, with
  the overall waiting in the loop be driven by io_uring"

* tag 'for-6.15/io_uring-epoll-wait-20250325' of git://git.kernel.dk/linux:
  io_uring/epoll: add support for IORING_OP_EPOLL_WAIT
  io_uring/epoll: remove CONFIG_EPOLL guards

include/uapi/linux/io_uring.h

@@ -280,6 +280,7 @@ enum io_uring_op {
 	IORING_OP_BIND,
 	IORING_OP_LISTEN,
 	IORING_OP_RECV_ZC,
+	IORING_OP_EPOLL_WAIT,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,