[GIT PULL] io_uring epoll reaping support

[Jens Axboe <axboe@kernel.dk>]

Hi Linus,

This sits on top of the recently sent out zero-copy rx pull request.

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.

Relies on a prep patch that went in via the VFS tree already. Please
pull!


The following changes since commit 0511f4e6a16988e485a5e60727c89e2ca9f83f44:

  Merge patch series "epoll changes for io_uring wait support" (2025-02-20 10:18:47 +0100)

are available in the Git repository at:

  git://git.kernel.dk/linux.git for-6.15/io_uring-rx-zc-20250325

for you to fetch changes up to 19f7e942732766aec8a51d217ab5fb4a7fe3bb0d:

  io_uring/epoll: add support for IORING_OP_EPOLL_WAIT (2025-02-20 07:59:56 -0700)

----------------------------------------------------------------
Jens Axboe (5):
      Merge branch 'for-6.15/io_uring' into for-6.15/io_uring-epoll-wait
      Merge branch 'for-6.15/io_uring-rx-zc' into for-6.15/io_uring-epoll-wait
      Merge branch 'vfs-6.15.eventpoll' of https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs into for-6.15/io_uring-epoll-wait
      io_uring/epoll: remove CONFIG_EPOLL guards
      io_uring/epoll: add support for IORING_OP_EPOLL_WAIT

 include/uapi/linux/io_uring.h |  1 +
 io_uring/Makefile             |  9 +++++----
 io_uring/epoll.c              | 35 +++++++++++++++++++++++++++++++++--
 io_uring/epoll.h              |  2 ++
 io_uring/opdef.c              | 14 ++++++++++++++
 5 files changed, 55 insertions(+), 6 deletions(-)

-- 
Jens Axboe