From: Jens Axboe <axboe@kernel.dk>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jann Horn <jannh@google.com>,
linux-aio@kvack.org, linux-block@vger.kernel.org,
Linux API <linux-api@vger.kernel.org>,
hch@lst.de, jmoyer@redhat.com, avi@scylladb.com,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 13/18] io_uring: add file set registration
Date: Wed, 6 Feb 2019 06:41:00 -0700 [thread overview]
Message-ID: <8f124de2-d6da-d656-25e4-b4d9e58f880e@kernel.dk> (raw)
In-Reply-To: <20190206005638.GU2217@ZenIV.linux.org.uk>
On 2/5/19 5:56 PM, Al Viro wrote:
> On Tue, Feb 05, 2019 at 12:08:25PM -0700, Jens Axboe wrote:
>> Proof is in the pudding, here's the main commit introducing io_uring
>> and now wiring it up to the AF_UNIX garbage collection:
>>
>> http://git.kernel.dk/cgit/linux-block/commit/?h=io_uring&id=158e6f42b67d0abe9ee84886b96ca8c4b3d3dfd5
>>
>> How does that look?
>
> In a word - wrong. Some theory: garbage collector assumes that there is
> a subset of file references such that
> * for all files with such references there's an associated unix_sock.
> * all such references are stored in SCM_RIGHTS datagrams that can be
> found by the garbage collector (currently: for data-bearing AF_UNIX sockets -
> queued SCM_RIGHTS datagrams, for listeners - SCM_RIGHTS datagrams sent via
> yet-to-be-accepted connections).
> * there is an efficient way to count those references for given file
> (->inflight of the corresponding unix_sock).
> * removal of those references would render the graph acyclic.
> * file can _NOT_ be subject to syscalls unless there are references
> to it outside of that subset.
IOW, we cannot use fget() for registering files, and we still need fget/fput
in the fast path to retain safe use of the file. If I'm understanding you
correctly?
Just trying to ensure that I understand what you're saying here, as it seems
to refer to the file registration part, not the main patch (which did get
reworked, though).
--
Jens Axboe
next prev parent reply other threads:[~2019-02-06 13:41 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190129192702.3605-1-axboe@kernel.dk>
[not found] ` <20190129192702.3605-14-axboe@kernel.dk>
2019-01-30 1:29 ` [PATCH 13/18] io_uring: add file set registration Jann Horn
2019-01-30 15:35 ` Jens Axboe
2019-02-04 2:56 ` Al Viro
2019-02-05 2:19 ` Jens Axboe
2019-02-05 17:57 ` Jens Axboe
2019-02-05 19:08 ` Jens Axboe
2019-02-06 0:27 ` Jens Axboe
2019-02-06 1:01 ` Al Viro
2019-02-06 17:56 ` Jens Axboe
2019-02-07 4:05 ` Al Viro
2019-02-07 16:14 ` Jens Axboe
2019-02-07 16:30 ` Al Viro
2019-02-07 16:35 ` Jens Axboe
2019-02-07 16:51 ` Al Viro
2019-02-06 0:56 ` Al Viro
2019-02-06 13:41 ` Jens Axboe [this message]
2019-02-07 4:00 ` Al Viro
2019-02-07 9:22 ` Miklos Szeredi
2019-02-07 13:31 ` Al Viro
2019-02-07 14:20 ` Miklos Szeredi
2019-02-07 15:20 ` Al Viro
2019-02-07 15:27 ` Miklos Szeredi
2019-02-07 16:26 ` Al Viro
2019-02-07 19:08 ` Miklos Szeredi
2019-02-07 18:45 ` Jens Axboe
2019-02-07 18:58 ` Jens Axboe
2019-02-11 15:55 ` Jonathan Corbet
2019-02-11 17:35 ` Al Viro
2019-02-11 20:33 ` Jonathan Corbet
2019-01-23 15:35 [PATCHSET v7] io_uring IO interface Jens Axboe
2019-01-23 15:35 ` [PATCH 13/18] io_uring: add file set registration Jens Axboe
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