io_uring/rsrc: extend buffer update

We need to pass more information to buffer registration than we can fit
into a single struct iovec. This patch allows users to optionally pass
struct io_uring_regbuf_desc. Apart from having more space for future use
cases, it also introduces registration types.

Currently, the type can be either of IO_REGBUF_TYPE_UADDR, which mirrors
the iovec path, or IO_REGBUF_TYPE_EMPTY for leaving a buffer table slot
empty. The next patch introduces a dmabuf backed type, and can be useful
for other extensions like splicing a list of user addresses (i.e.
iovec[]), interoperability with zcrx, kernel allocated memory like was
brough up by Cristoph. Note, the type only represents a registration
option, which is distinct from how io_uring internally stores it.

The flags field is not used yet but always useful to have, e.g. we can
encode read-only / write-only restrictions using it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/0d60f1ebab80ef594a78ea27c2edd5ad33faa640.1791975048.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions