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From: Jens Axboe <axboe@kernel.dk>
To: Stefan Metzmacher <metze@samba.org>, io-uring@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk
Subject: Re: [PATCH 3/6] io_uring: add support for IORING_OP_OPENAT
Date: Wed, 8 Jan 2020 09:20:05 -0700
Message-ID: <4ccb935c-7ff9-592f-8c27-0af3d38326d7@kernel.dk> (raw)
In-Reply-To: <82a015c4-f5b9-7c85-7d80-78964cb0d82e@samba.org>

On 1/8/20 6:05 AM, Stefan Metzmacher wrote:
> Hi Jens,
> 
>> This works just like openat(2), except it can be performed async. For
>> the normal case of a non-blocking path lookup this will complete
>> inline. If we have to do IO to perform the open, it'll be done from
>> async context.
> 
> Did you already thought about the credentials being used for the async
> open? The application could call setuid() and similar calls to change
> the credentials of the userspace process/threads. In order for
> applications like samba to use this async openat, it would be required
> to specify the credentials for each open, as we have to multiplex
> requests from multiple user sessions in one process.
> 
> This applies to non-fd based syscall. Also for an async connect
> to a unix domain socket.
> 
> Do you have comments on this?

The open works like any of the other commands, it inherits the
credentials that the ring was setup with. Same with the memory context,
file table, etc. There's currently no way to have multiple personalities
within a single ring.

Sounds like you'd like an option for having multiple personalities
within a single ring? I think it would be better to have a ring per
personality instead. One thing we could do to make this more lightweight
is to have rings that are associated, so that we can share a lot of the
backend processing between them.

-- 
Jens Axboe


  reply index

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 [this message]
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
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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