io_uring/rsrc: add dmabuf backed registered buffers

Implement dmabuf backed registered buffers. To register them, the user
should specify IO_REGBUF_TYPE_DMABUF for the regitration and pass the
desired dmabuf fd and a file for which it should be registered.

>From there, it can be used with io_uring read/write requests
IORING_OP_{READ,WRITE}_FIXED) as normal. The requests should be issued
against the file specified during registration, and otherwise they'll be
failed. The user should also be prepared to handle spurious -EAGAIN by
reissuing the request.

Internally, dmabuf registered buffers is an optin feature for io_uring
request opcodes and they should pass a special flag on import to use it.

Suggested-by: David Wei <dw@davidwei.uk>
Suggested-by: Vishal Verma <vishal1.verma@intel.com>
Suggested-by: Tushar Gohad <tushar.gohad@intel.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/4aa230df871ee275536f367087b44ebfebb88cc1.1791975048.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions