linux-kernel - Re: [RFC] splice/tee: len=0 fast path after validity check

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Date:   Sat, 9 May 2020 19:03:03 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     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: [RFC] splice/tee: len=0 fast path after validity check

On 09/05/2020 17:42, Jens Axboe wrote:
> On 5/9/20 2:46 AM, Pavel Begunkov wrote:
>> When len=0, splice() and tee() return 0 even if specified fds are
>> invalid, hiding errors from users. Move len=0 optimisation later after
>> basic validity checks.
>>
>> before:
>> splice(len=0, fd_in=-1, ...) == 0;
>>
>> after:
>> splice(len=0, fd_in=-1, ...) == -EBADF;
> 
> I'm not sure what the purpose of this would be. It probably should have
> been done that way from the beginning, but it wasn't.  While there's
> very little risk of breaking any applications due to this change, it
> also seems like a pointless exercise at this point.
> 
> So my suggestion would be to just leave it alone.

Ok

-- 
Pavel Begunkov