From: Pavel Begunkov <[email protected]>
To: Stefan Metzmacher <[email protected]>, Jens Axboe <[email protected]>,
[email protected]
Cc: [email protected], [email protected]
Subject: Re: [PATCHSET v2 0/6] io_uring: add support for open/close
Date: Mon, 20 Jan 2020 16:04:44 +0300 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 1/20/2020 3:15 PM, Stefan Metzmacher wrote:
> Hi Jens,
>
>>> Thanks!
>>>
>>> Another great feature would the possibility to make use of the
>>> generated fd in the following request.
>>>
>>> This is a feature that's also available in the SMB3 protocol
>>> called compound related requests.
>>>
>>> The client can compound a chain with open, getinfo, read, close
>>> getinfo, read and close get an file handle of -1 and implicitly
>>> get the fd generated/used in the previous request.
>>
>> Right, the "plan" there is to utilize BPF to make this programmable.
>> We really need something more expressive to be able to pass information
>> between SQEs that are linked, or even to decide which link to run
>> depending on the outcome of the parent.
>>
>> There's a lot of potential there!
>
> I guess so, but I don't yet understand how BPF works in real life.
>
> Is it possible to do that as normal user without special privileges?
>
> My naive way would be using some flags and get res and pass fd by reference.
>
Just have been discussing related stuff. See the link if curious
https://github.com/axboe/liburing/issues/58
To summarise, there won't be enough flags to cover all use-cases and it
will slow down the common path. There should be something with
zero-overhead if the feature is not used, and that's not the case with
flags. That's why it'd be great to have a custom eBPF program
(in-kernel) controlling what and how to do next.
I don't much about eBPF internals, but probably we will be able to
attach an eBPF program to io_uring instance. Though, not sure whether it
could be done without privileges.
--
Pavel Begunkov
next prev parent reply other threads:[~2020-01-20 13:04 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 17:00 [PATCHSET v2 0/6] io_uring: add support for open/close Jens Axboe
2020-01-07 17:00 ` [PATCH 1/6] fs: add namei support for doing a non-blocking path lookup Jens Axboe
2020-01-25 13:15 ` Jeff Layton
2020-01-07 17:00 ` [PATCH 2/6] fs: make build_open_flags() available internally Jens Axboe
2020-01-07 17:00 ` [PATCH 3/6] io_uring: add support for IORING_OP_OPENAT Jens Axboe
2020-01-08 13:05 ` Stefan Metzmacher
2020-01-08 16:20 ` Jens Axboe
2020-01-08 16:32 ` Stefan Metzmacher
2020-01-08 16:40 ` Jens Axboe
2020-01-08 17:04 ` Stefan Metzmacher
2020-01-08 22:53 ` Jens Axboe
2020-01-08 23:03 ` Stefan Metzmacher
2020-01-08 23:05 ` Jens Axboe
2020-01-08 23:11 ` Stefan Metzmacher
2020-01-08 23:22 ` Jens Axboe
2020-01-09 10:40 ` Stefan Metzmacher
2020-01-09 21:31 ` Jens Axboe
2020-01-16 22:42 ` Stefan Metzmacher
2020-01-17 0:16 ` Jens Axboe
2020-01-07 17:00 ` [PATCH 4/6] fs: move filp_close() outside of __close_fd_get_file() Jens Axboe
2020-01-07 17:00 ` [PATCH 5/6] io-wq: add support for uncancellable work Jens Axboe
2020-01-07 17:00 ` [PATCH 6/6] io_uring: add support for IORING_OP_CLOSE Jens Axboe
2020-01-08 21:17 ` [PATCHSET v2 0/6] io_uring: add support for open/close Stefan Metzmacher
2020-01-08 22:57 ` Jens Axboe
2020-01-08 23:05 ` Stefan Metzmacher
2020-01-09 1:02 ` Jens Axboe
2020-01-09 2:03 ` Jens Axboe
2020-01-16 22:50 ` Stefan Metzmacher
2020-01-17 0:18 ` Jens Axboe
2020-01-20 12:15 ` Stefan Metzmacher
2020-01-20 13:04 ` Pavel Begunkov [this message]
2020-01-17 0:44 ` Colin Walters
2020-01-17 0:51 ` Jens Axboe
2020-01-17 9:32 ` Pavel Begunkov
2020-01-17 15:21 ` Jens Axboe
2020-01-17 22:27 ` Pavel Begunkov
2020-01-17 22:36 ` Jens Axboe
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