Re: [PATCH v1 10/11] io_uring/kbuf: return buffer id in buffer selection

[Jens Axboe <axboe@kernel.dk>]

On 2/9/26 5:28 PM, Joanne Koong wrote:
> Return the id of the selected buffer in io_buffer_select(). This is
> needed for kernel-managed buffer rings to later recycle the selected
> buffer.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> ---
>  include/linux/io_uring/cmd.h   | 2 +-
>  include/linux/io_uring_types.h | 2 ++
>  io_uring/kbuf.c                | 7 +++++--
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
> index d4b5943bdeb1..94df2bdebe77 100644
> --- a/include/linux/io_uring/cmd.h
> +++ b/include/linux/io_uring/cmd.h
> @@ -71,7 +71,7 @@ void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd);
>  
>  /*
>   * Select a buffer from the provided buffer group for multishot uring_cmd.
> - * Returns the selected buffer address and size.
> + * Returns the selected buffer address, size, and id.
>   */
>  struct io_br_sel io_uring_cmd_buffer_select(struct io_uring_cmd *ioucmd,
>  					    unsigned buf_group, size_t *len,
> diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
> index 36cc2e0346d9..5a56bb341337 100644
> --- a/include/linux/io_uring_types.h
> +++ b/include/linux/io_uring_types.h
> @@ -100,6 +100,8 @@ struct io_br_sel {
>  		void *kaddr;
>  	};
>  	ssize_t val;
> +	/* id of the selected buffer */
> +	unsigned buf_id;
>  };

I'm probably missing something here, but why can't the caller just use
req->buf_index for this?

-- 
Jens Axboe