Re: [PATCHv4 1/5] io_uring: move fixed buffer import to issue path

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

On Tue, Feb 18, 2025 at 02:42:25PM -0800, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Similar to the fixed file path, requests may depend on a previous one
> to set up an index, so we need to allow linking them. The prep callback
> happens too soon for linked commands, so the lookup needs to be deferred
> to the issue path. Change the prep callbacks to just set the buf_index
> and let generic io_uring code handle the fixed buffer node setup, just
> like it already does for fixed files.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---

...

> diff --git a/io_uring/net.c b/io_uring/net.c
> index 000dc70d08d0d..39838e8575b53 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -1373,6 +1373,10 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  #endif
>  	if (unlikely(!io_msg_alloc_async(req)))
>  		return -ENOMEM;
> +	if (zc->flags & IORING_RECVSEND_FIXED_BUF) {
> +		req->buf_index = zc->buf_index;
> +		req->flags |= REQ_F_FIXED_BUFFER;
> +	}
>  	if (req->opcode != IORING_OP_SENDMSG_ZC)
>  		return io_send_setup(req, sqe);
>  	return io_sendmsg_setup(req, sqe);
> @@ -1434,25 +1438,10 @@ static int io_send_zc_import(struct io_kiocb *req, unsigned int issue_flags)
>  	struct io_async_msghdr *kmsg = req->async_data;
>  	int ret;
>  
> -	if (sr->flags & IORING_RECVSEND_FIXED_BUF) {
> -		struct io_ring_ctx *ctx = req->ctx;
> -		struct io_rsrc_node *node;
> -
> -		ret = -EFAULT;
> -		io_ring_submit_lock(ctx, issue_flags);
> -		node = io_rsrc_node_lookup(&ctx->buf_table, sr->buf_index);
> -		if (node) {
> -			io_req_assign_buf_node(sr->notif, node);

Here the node buffer is assigned to ->notif req, instead of the current
request, and you may have to deal with this case here.

Otherwise, this patch looks fine:

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



Thanks,
Ming