On 24/02/2020 21:23, Jens Axboe wrote:
> On 2/24/20 10:55 AM, Pavel Begunkov wrote:
>> +static int copy_single(struct io_uring *ring,
>> +			int fd_in, loff_t off_in,
>> +			int fd_out, loff_t off_out,
>> +			int pipe_fds[2],
>> +			unsigned int len,
>> +			unsigned flags1, unsigned flags2)
>> +{
>> +	struct io_uring_cqe *cqe;
>> +	struct io_uring_sqe *sqe;
>> +	int i, ret = -1;
>> +
>> +	sqe = io_uring_get_sqe(ring);
>> +	if (!sqe) {
>> +		fprintf(stderr, "get sqe failed\n");
>> +		return -1;
>> +	}
>> +	io_uring_prep_splice(sqe, fd_in, off_in, pipe_fds[1], -1,
>> +			     len, flags1);
>> +	sqe->flags = IOSQE_IO_LINK;
>> +
>> +	sqe = io_uring_get_sqe(ring);
>> +	if (!sqe) {
>> +		fprintf(stderr, "get sqe failed\n");
>> +		return -1;
>> +	}
>> +	io_uring_prep_splice(sqe, pipe_fds[0], -1, fd_out, off_out,
>> +			     len, flags2);
>> +
>> +	ret = io_uring_submit(ring);
>> +	if (ret <= 1) {
>> +		fprintf(stderr, "sqe submit failed: %d\n", ret);
>> +		return -1;
>> +	}
> 
> This seems wrong, you prep one and submit, the right return value would
> be 1. This check should be < 1, not <= 1. I'll make the change, rest
> looks good to me. Thanks!
> 

There are 2 sqes, "fd_in -> pipe" and "pipe -> fd_out".

-- 
Pavel Begunkov