Re: [PATCH] io_uring/uring_cmd: explicitly disallow cancelations for IOPOLL

[Ming Lei <ming.lei@redhat.com>]

On Wed, Jan 14, 2026 at 08:52:31AM -0700, Jens Axboe wrote:
> This currently isn't supported, and due to a recent commit, it also
> cannot easily be supported by io_uring due to hash_node and IOPOLL
> completion data overlapping.
> 
> This can be revisited if we ever do support cancelations of requests
> that have gone to the block stack.
> 
> Suggested-by: Ming Lei <ming.lei@redhat.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> ---
> 
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index 197474911f04..ee7b49f47cb5 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -104,6 +104,15 @@ void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
>  	struct io_kiocb *req = cmd_to_io_kiocb(cmd);
>  	struct io_ring_ctx *ctx = req->ctx;
>  
> +	/*
> +	 * Doing cancelations on IOPOLL requests are not supported. Both
> +	 * because they can't get canceled in the block stack, but also
> +	 * because iopoll completion data overlaps with the hash_node used
> +	 * for tracking.
> +	 */
> +	if (ctx->flags & IORING_SETUP_IOPOLL)
> +		return;

Maybe better to add warn_on_once(), but not a big deal, anyway:

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming