Re: [PATCH] io_uring: fixup a few spots where link failure isn't flagged

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

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On 06/11/2019 06:32, Jens Axboe wrote:
> If a request fails, we need to ensure we set REQ_F_FAIL_LINK on it if
> REQ_F_LINK is set. Any failure in the chain should break the chain.
> 
> We were missing a few spots where this should be done. It might be nice
> to generalize this somewhat at some point, as long as we factor in the
> fact that failure looks different for each request type.
> 

The completion path also starts to get complicated, especially
non-uniform handling of links there.

i.e. io_put_req() -> io_put_req_find_next() ->
	io_free_req() -> __io_free_req()
Plus, io_free_req_many(), which can be used only in some cases.

My compiler didn't even inlined it, so there are 4 CALLs.
Though, still in TODO list.


> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> --
> 
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index bda27b52fd5b..4edc94aab17e 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1672,6 +1672,8 @@ static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>  	}
>  
>  	io_cqring_add_event(req->ctx, sqe->user_data, ret);
> +	if (ret < 0 && (req->flags & REQ_F_LINK))
> +		req->flags |= REQ_F_FAIL_LINK;
>  	io_put_req(req, nxt);
>  	return 0;
>  }
> @@ -1787,6 +1789,8 @@ static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	spin_unlock_irq(&ctx->completion_lock);
>  
>  	io_cqring_add_event(req->ctx, sqe->user_data, ret);
> +	if (ret < 0 && (req->flags & REQ_F_LINK))
> +		req->flags |= REQ_F_FAIL_LINK;
>  	io_put_req(req, NULL);
>  	return 0;
>  }
> @@ -1994,6 +1998,8 @@ static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
>  	spin_unlock_irqrestore(&ctx->completion_lock, flags);
>  
>  	io_cqring_ev_posted(ctx);
> +	if (req->flags & REQ_F_LINK)
> +		req->flags |= REQ_F_FAIL_LINK;
>  	io_put_req(req, NULL);
>  	return HRTIMER_NORESTART;
>  }
> @@ -2035,6 +2041,8 @@ static int io_timeout_remove(struct io_kiocb *req,
>  		io_commit_cqring(ctx);
>  		spin_unlock_irq(&ctx->completion_lock);
>  		io_cqring_ev_posted(ctx);
> +		if (req->flags & REQ_F_LINK)
> +			req->flags |= REQ_F_FAIL_LINK;
>  		io_put_req(req, NULL);
>  		return 0;
>  	}
> @@ -2328,6 +2336,8 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
>  	io_put_req(req, NULL);
>  
>  	if (ret) {
> +		if (req->flags & REQ_F_LINK)
> +			req->flags |= REQ_F_FAIL_LINK;
>  		io_cqring_add_event(ctx, sqe->user_data, ret);
>  		io_put_req(req, NULL);
>  	}
> 

-- 
Pavel Begunkov


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