Re: [PATCH v2 10/24] io_uring: add a helper for batch free

[Hao Xu <haoxu@linux.alibaba.com>]

在 2021/9/25 上午4:59, Pavel Begunkov 写道:
> Add a helper io_free_batch_list(), which takes a single linked list and
> puts/frees all requests from it in an efficient manner. Will be reused
> later.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>   fs/io_uring.c | 34 +++++++++++++++++++++-------------
>   1 file changed, 21 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 205127394649..ad8af05af4bc 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2308,12 +2308,31 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req,
>   	wq_stack_add_head(&req->comp_list, &state->free_list);
>   }
>   
> +static void io_free_batch_list(struct io_ring_ctx *ctx,
> +			       struct io_wq_work_list *list)
> +	__must_hold(&ctx->uring_lock)
> +{
> +	struct io_wq_work_node *node;
> +	struct req_batch rb;
> +
> +	io_init_req_batch(&rb);
> +	node = list->first;
> +	do {
> +		struct io_kiocb *req = container_of(node, struct io_kiocb,
> +						    comp_list);
> +
> +		node = req->comp_list.next;
> +		if (req_ref_put_and_test(req))
> +			io_req_free_batch(&rb, req, &ctx->submit_state);
> +	} while (node);
> +	io_req_free_batch_finish(ctx, &rb);
> +}
Hi Pavel, Why not we use the wq_list_for_each here as well?
> +
>   static void __io_submit_flush_completions(struct io_ring_ctx *ctx)
>   	__must_hold(&ctx->uring_lock)
>   {
>   	struct io_wq_work_node *node, *prev;
>   	struct io_submit_state *state = &ctx->submit_state;
> -	struct req_batch rb;
>   
>   	spin_lock(&ctx->completion_lock);
>   	wq_list_for_each(node, prev, &state->compl_reqs) {
> @@ -2327,18 +2346,7 @@ static void __io_submit_flush_completions(struct io_ring_ctx *ctx)
>   	spin_unlock(&ctx->completion_lock);
>   	io_cqring_ev_posted(ctx);
>   
> -	io_init_req_batch(&rb);
> -	node = state->compl_reqs.first;
> -	do {
> -		struct io_kiocb *req = container_of(node, struct io_kiocb,
> -						    comp_list);
> -
> -		node = req->comp_list.next;
> -		if (req_ref_put_and_test(req))
> -			io_req_free_batch(&rb, req, &ctx->submit_state);
> -	} while (node);
> -
> -	io_req_free_batch_finish(ctx, &rb);
> +	io_free_batch_list(ctx, &state->compl_reqs);
>   	INIT_WQ_LIST(&state->compl_reqs);
>   }
>   
>