Josh Triplett 6e76ac5958 io_uring: Add io_uring_setup flag to pre-register ring fd and never install it
With IORING_REGISTER_USE_REGISTERED_RING, an application can register
the ring fd and use it via registered index rather than installed fd.
This allows using a registered ring for everything *except* the initial
mmap.

With IORING_SETUP_NO_MMAP, io_uring_setup uses buffers allocated by the
user, rather than requiring a subsequent mmap.

The combination of the two allows a user to operate *entirely* via a
registered ring fd, making it unnecessary to ever install the fd in the
first place. So, add a flag IORING_SETUP_REGISTERED_FD_ONLY to make
io_uring_setup register the fd and return a registered index, without
installing the fd.

This allows an application to avoid touching the fd table at all, and
allows a library to never even momentarily install a file descriptor.

This splits out an io_ring_add_registered_file helper from
io_ring_add_registered_fd, for use by io_uring_setup.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Link: https://lore.kernel.org/r/bc8f431bada371c183b95a83399628b605e978a3.1682699803.git.josh@joshtriplett.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-05-16 08:06:00 -06:00
..
2023-04-25 18:44:10 -07:00
2023-05-05 12:56:55 -07:00
2023-05-01 12:06:20 -07:00
2023-05-10 09:27:20 +01:00
2023-04-16 11:08:07 +03:00
2023-04-27 11:53:57 -07:00
2023-04-24 15:15:31 +02:00
2023-04-29 11:04:14 -07:00
2023-04-26 15:39:25 -07:00