From: Stefan Metzmacher <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Cc: [email protected], [email protected]
Subject: Re: [PATCHSET v2 0/6] Support selectable file descriptors
Date: Mon, 9 Mar 2020 21:33:21 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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Hi Jens,
> One of the fabled features with chains has long been the desire to
> support things like:
>
> <open fileX><read from fileX><close fileX>
>
> in a single chain. This currently doesn't work, since the read/close
> depends on what file descriptor we get on open.
>
> The original attempt at solving this provided a means to pass
> descriptors between chains in a link, this version takes a different
> route. Based on Josh's support for O_SPECIFIC_FD, we can instead control
> what fd value we're going to get out of open (or accept). With that in
> place, we don't need to do any magic to make this work. The above chain
> then becomes:
>
> <open fileX with fd Y><read from fd Y><close fd Y>
>
> which is a lot more useful, and allows any sort of weird chains without
> needing to nest "last open" file descriptors.
I like that approach, however I'm wondering if this able to be used by
libraries as it requires coordination of fd values within the whole
process. I don't think this would be a reason to block that feature,
but it might be good to be added to the manpages.
As future addition I'd like to get support for something similar
but for io_uring fixed file slots. That could also be used by libraries
using a private ring fd.
metze
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prev parent reply other threads:[~2020-03-09 20:33 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-04 18:00 [PATCHSET v2 0/6] Support selectable file descriptors Jens Axboe
2020-03-04 18:00 ` [PATCH 1/6] fs: openat2: Extend open_how to allow userspace-selected fds Jens Axboe
2020-03-04 18:00 ` [PATCH 2/6] io_uring: move CLOSE req->file checking into handler Jens Axboe
2020-03-04 18:00 ` [PATCH 3/6] io_uring: move read/write side file based prep into op handler Jens Axboe
2020-03-04 18:00 ` [PATCH 4/6] io_uring: support deferred retrival of file from fd Jens Axboe
2020-03-04 18:00 ` [PATCH 5/6] net: allow specific fd selection for __sys_accept4_file() Jens Axboe
2020-03-04 18:00 ` [PATCH 6/6] io_uring: allow specific fd for IORING_OP_ACCEPT Jens Axboe
2020-03-04 19:02 ` Josh Triplett
2020-03-04 19:09 ` Jens Axboe
2020-03-04 19:51 ` Josh Triplett
2020-03-04 19:03 ` [PATCHSET v2 0/6] Support selectable file descriptors Josh Triplett
2020-03-04 19:10 ` Jens Axboe
2020-03-04 19:28 ` Jeff Layton
2020-03-04 19:50 ` Jens Axboe
2020-03-04 19:56 ` Josh Triplett
2020-03-04 20:00 ` Jens Axboe
2020-03-04 20:09 ` Josh Triplett
2020-03-04 20:14 ` Jens Axboe
2020-03-09 20:33 ` Stefan Metzmacher [this message]
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