Re: [PATCHv7 1/6] io_uring/rw: move fixed buffer import to issue path

[Keith Busch <kbusch@kernel.org>]

On Wed, Feb 26, 2025 at 01:20:24PM -0700, Jens Axboe wrote:
> +static int io_rw_do_import(struct io_kiocb *req, int ddir)
> +{
> +	if (!io_do_buffer_select(req)) {
> +		struct io_async_rw *io = req->async_data;
> +		int ret;
> +
> +		ret = io_import_rw_buffer(ddir, req, io, 0);
> +		if (unlikely(ret))
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
> +		      int ddir)
> +{
> +	int ret;
> +
> +	ret = __io_prep_rw(req, sqe, ddir);
> +	if (unlikely(ret))
> +		return ret;
> +
> +	return io_rw_do_import(req, ddir);
> +}

...

>  static int io_prep_rwv(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>  		       int ddir)
>  {
> -	const bool do_import = !(req->flags & REQ_F_BUFFER_SELECT);
>  	int ret;
>  
> -	ret = io_prep_rw(req, sqe, ddir, do_import);
> +	ret = io_prep_rw(req, sqe, ddir);
>  	if (unlikely(ret))
>  		return ret;
> -	if (do_import)
> -		return 0;
> +	if (!(req->flags & REQ_F_BUFFER_SELECT))
> +		return io_rw_do_import(req, ddir);

Not sure if I'm missing something subtle here, but wanted to point out
I've changed the above in the version I'm about to send: io_prep_rw()
already calls io_rw_do_import(), so we can just return 0 here.