From: Jens Axboe <axboe@kernel.dk>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Theodore Ts'o <tytso@mit.edu>, Christoph Hellwig <hch@lst.de>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHSET 0/2] Fix splice from random/urandom
Date: Thu, 19 May 2022 18:56:12 -0600 [thread overview]
Message-ID: <84d073aa-9937-1a58-dd7a-b1828874c21a@kernel.dk> (raw)
In-Reply-To: <YobldmDn6pU9mr4f@zx2c4.com>
On 5/19/22 6:48 PM, Jason A. Donenfeld wrote:
> Hi Jens,
>
> On Thu, May 19, 2022 at 06:02:55PM -0600, Jens Axboe wrote:
>> On 5/19/22 6:00 PM, Jason A. Donenfeld wrote:
>>> Hi Jens,
>>>
>>> On Fri, May 20, 2022 at 1:57 AM Jens Axboe <axboe@kernel.dk> wrote:
>>>>
>>>> On 5/19/22 5:27 PM, Jason A. Donenfeld wrote:
>>>>> Hi Jens,
>>>>>
>>>>> On Fri, May 20, 2022 at 1:25 AM Jens Axboe <axboe@kernel.dk> wrote:
>>>>>> I'll leave that to you :-)
>>>>>
>>>>> Alright, I'll have a look. Which one do I want here? This series adds
>>>>> splice_read/splice_write. The new thing would be sendpage? Or
>>>>> copy_file_range? Or something else?
>>>>
>>>> For copying kernel memory? It's really the same thing, you just
>>>> initialize the iter as an ITER_KVEC instead. The nice thing about the
>>>> iov_iter iterator that it then hides that for you, call the same copy
>>>> in/out helpers for it.
>>>
>>> Err, maybe we're talking about different things? I was thinking about
>>> the plumbing to make splice/sendfile work on non-pipes.
>>
>> Ah I see. sendfile() just uses splice() internally, so that'll work
>> (again) with my changes. splice(), by definition, either moves to and
>> from a pipe. Hence one of the fds must be a pipe. Does that answer the
>> question?
>
> sendfile() returns -EINVAL even with your patches. Only splicing to pipes
> seems to work.
Huh, that really should work. Are you trying to sendfile() to random? If
so, you need that last write_iter patch too, and add the splice_write as
I mentioned.
--
Jens Axboe
next prev parent reply other threads:[~2022-05-20 0:56 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 19:31 [PATCHSET 0/2] Fix splice from random/urandom Jens Axboe
2022-05-19 19:31 ` [PATCH 1/2] random: convert to using fops->read_iter() Jens Axboe
2022-05-19 23:12 ` Jason A. Donenfeld
2022-05-19 23:20 ` Jason A. Donenfeld
2022-05-19 23:21 ` Jens Axboe
2022-05-19 23:21 ` Jason A. Donenfeld
2022-05-19 23:21 ` Jens Axboe
2022-05-19 19:31 ` [PATCH 2/2] random: wire up fops->splice_read_iter() Jens Axboe
2022-05-19 19:48 ` [PATCHSET 0/2] Fix splice from random/urandom Christoph Hellwig
2022-05-19 19:55 ` Jens Axboe
2022-05-20 6:02 ` Christoph Hellwig
2022-05-20 12:51 ` Jens Axboe
2022-05-19 20:05 ` Jason A. Donenfeld
2022-05-19 20:49 ` Jens Axboe
2022-05-19 21:02 ` Jens Axboe
2022-05-19 23:15 ` Jason A. Donenfeld
2022-05-19 23:22 ` Jens Axboe
2022-05-19 23:25 ` Jason A. Donenfeld
2022-05-19 23:33 ` Jens Axboe
2022-05-19 23:39 ` Jason A. Donenfeld
2022-05-19 23:44 ` Jens Axboe
2022-05-19 23:13 ` Jason A. Donenfeld
2022-05-19 23:19 ` Jens Axboe
2022-05-19 23:23 ` Jason A. Donenfeld
2022-05-19 23:25 ` Jens Axboe
2022-05-19 23:27 ` Jason A. Donenfeld
2022-05-19 23:57 ` Jens Axboe
2022-05-20 0:00 ` Jason A. Donenfeld
2022-05-20 0:02 ` Jens Axboe
2022-05-20 0:48 ` Jason A. Donenfeld
2022-05-20 0:56 ` Jens Axboe [this message]
2022-05-20 1:00 ` Jason A. Donenfeld
2022-05-20 1:05 ` Jens Axboe
2022-05-20 1:10 ` Jens Axboe
2022-05-20 12:43 ` Jason A. Donenfeld
2022-05-20 12:49 ` Jens Axboe
2022-05-20 13:04 ` Jason A. Donenfeld
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