linux-kernel - Re: [PATCH v2 3/3] io_uring: add splice(2) support

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Date:   Mon, 17 Feb 2020 18:40:44 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Stefan Metzmacher <metze@...ba.org>, Jens Axboe <axboe@...nel.dk>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        io-uring@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] io_uring: add splice(2) support

On 2/17/2020 6:18 PM, Stefan Metzmacher wrote:
> Hi Pavel,
> 
>> +static int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>> +{
>> +	struct io_splice* sp = &req->splice;
>> +	unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL;
>> +	int ret;
>> +
>> +	if (req->flags & REQ_F_NEED_CLEANUP)
>> +		return 0;
>> +
>> +	sp->file_in = NULL;
>> +	sp->off_in = READ_ONCE(sqe->off_in);
>> +	sp->off_out = READ_ONCE(sqe->off);
>> +	sp->len = READ_ONCE(sqe->len);
>> +	sp->flags = READ_ONCE(sqe->splice_flags);
>> +
>> +	if (unlikely(READ_ONCE(sqe->ioprio) || (sp->flags & ~valid_flags)))
>> +		return -EINVAL;
> 
> Why is ioprio not supported?

Because there is no way to set it without changing much of splice code.
It may be added later

BTW, it seems, only opcodes cares about ioprio are read*/write*.
recv*() and send*() don't reject it, but never use.

-- 
Pavel Begunkov