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From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>, [email protected]
Subject: Re: [PATCH liburing v5 2/2] test/splice: add basic splice tests
Date: Mon, 24 Feb 2020 11:33:46 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 2/24/20 11:26 AM, Pavel Begunkov wrote:
> 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".

I must be blind... I guess the failure case is that it doesn't work so well
on the kernels not supporting splice, as we'll return 1 there as the first
submit fails. I'll clean up that bit.

-- 
Jens Axboe


  reply	other threads:[~2020-02-24 18:33 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-24 17:54 [PATCH v5 0/2] splice helpers + tests Pavel Begunkov
2020-02-24 17:55 ` [PATCH liburing v5 1/2] splice: add splice(2) helpers Pavel Begunkov
2020-02-24 17:55 ` [PATCH liburing v5 2/2] test/splice: add basic splice tests Pavel Begunkov
2020-02-24 18:23   ` Jens Axboe
2020-02-24 18:26     ` Pavel Begunkov
2020-02-24 18:33       ` Jens Axboe [this message]
2020-02-24 18:39         ` Pavel Begunkov
2020-02-24 18:41           ` Jens Axboe
2020-02-24 18:47             ` Pavel Begunkov
2020-02-24 19:30               ` Jens Axboe

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