Re: [PATCH 1/1] io_uring/msg_ring: let target know allocated index

[Pavel Begunkov <asml.silence@gmail.com>]

On 3/16/23 12:11, Pavel Begunkov wrote:
> msg_ring requests transferring files support auto index selection via
> IORING_FILE_INDEX_ALLOC, however they don't return the selected index
> to the target ring and there is no other good way for the userspace to
> know where is the receieved file.

Weird, there are two identical mails with the patch, please
ignore either of them.

  
> Return the index for allocated slots and 0 otherwise, which is
> consistent with other fixed file installing requests.
> 
> Cc: stable@vger.kernel.org # v6.0+
> Fixes: e6130eba8a848 ("io_uring: add support for passing fixed file descriptors")
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>   io_uring/msg_ring.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
> index 8803c0979e2a..85fd7ce5f05b 100644
> --- a/io_uring/msg_ring.c
> +++ b/io_uring/msg_ring.c
> @@ -202,7 +202,7 @@ static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flag
>   	 * completes with -EOVERFLOW, then the sender must ensure that a
>   	 * later IORING_OP_MSG_RING delivers the message.
>   	 */
> -	if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
> +	if (!io_post_aux_cqe(target_ctx, msg->user_data, ret, 0))
>   		ret = -EOVERFLOW;
>   out_unlock:
>   	io_double_unlock_ctx(target_ctx);
> @@ -229,6 +229,8 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
>   	struct io_ring_ctx *ctx = req->ctx;
>   	struct file *src_file = msg->src_file;
>   
> +	if (msg->len)
> +		return -EINVAL;
>   	if (target_ctx == ctx)
>   		return -EINVAL;
>   	if (target_ctx->flags & IORING_SETUP_R_DISABLED)

-- 
Pavel Begunkov