Re: [PATCH v5 0/5] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL

[Caleb Sander Mateos <csander@purestorage.com>]

On Mon, Mar 16, 2026 at 6:01 PM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 3/16/26 4:14 PM, Jens Axboe wrote:
> >
> > On Mon, 02 Mar 2026 10:29:09 -0700, Caleb Sander Mateos wrote:
> >> Currently, creating an io_uring with IORING_SETUP_IOPOLL requires all
> >> requests issued to it to support iopoll. This prevents, for example,
> >> using ublk zero-copy together with IORING_SETUP_IOPOLL, as ublk
> >> zero-copy buffer registrations are performed using a uring_cmd. There's
> >> no technical reason why these non-iopoll uring_cmds can't be supported.
> >> They will either complete synchronously or via an external mechanism
> >> that calls io_uring_cmd_done(), io_uring_cmd_post_mshot_cqe32(), or
> >> io_uring_mshot_cmd_post_cqe(), so they don't need to be polled.
> >>
> >> [...]
> >
> > Applied, thanks!
> >
> > [1/5] io_uring: add REQ_F_IOPOLL
> >       commit: 9165dc4fa969b64c2d4396ee4e1546a719978dd1
> > [2/5] io_uring: remove iopoll_queue from struct io_issue_def
> >       commit: 7995be40deb3ab8b5df7bdf0621f33aa546aefa7
> > [3/5] io_uring: count CQEs in io_iopoll_check()
> >       commit: 3a5e96d47f7ea37fb6adf37882eec1521f8ca75e
> > [4/5] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL
> >       commit: 23475637b0c47e5028817c9fd4dabe8f7409ca6c
> > [5/5] nvme: remove nvme_dev_uring_cmd() IO_URING_F_IOPOLL check
> >       commit: f144dbac4b177cfd026e417ab98da518ff3372cb
>
> Caleb, want to send the liburing tests and documentation updates too?

Sure. What type of file do you recommend using for non-iopoll
uring_cmds? Most of them seem to have relatively specific hardware
(e.g. blkdev_uring_cmd, nvme_dev_uring_cmd) or kernel configuration
(e.g. ublk_ch_uring_cmd, io_mock_cmd) requirements, as well as
requiring elevated permissions. Maybe io_uring_cmd_sock would be the
most general?

Best,
Caleb