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From: Avi Kivity <avi@scylladb.com>
To: Goldwyn Rodrigues <rgoldwyn@suse.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-xfs@vger.kernel.org
Subject: Detecting RWF_NOWAIT support
Date: Thu, 14 Dec 2017 19:38:34 +0200	[thread overview]
Message-ID: <b45afd09-5fa8-74ac-4ba4-9dc9074e30cf@scylladb.com> (raw)

I'm looking to add support for RWF_NOWAIT within a linux-aio iocb. 
Naturally, I need to detect at runtime whether the kernel support 
RWF_NOWAIT or not.


The only method I could find was to issue an I/O with RWF_NOWAIT set, 
and look for errors. This is somewhat less than perfect:

  - from the error, I can't tell whether RWF_NOWAIT was the problem, or 
something else. If I enable a number of new features, I have to run 
through all combinations to figure out which ones are supported and 
which are not.

  - RWF_NOWAIT support is per-filesystem, so I can't just remember not 
to enable RWF_NOWAIT globally, I have to track it per file.


Did I miss another method of detecting RWF_NOWAIT?

             reply	other threads:[~2017-12-14 17:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-14 17:38 Avi Kivity [this message]
2017-12-14 19:15 ` Goldwyn Rodrigues
2017-12-16 14:49   ` Avi Kivity
2017-12-16 18:03     ` vcaputo
2017-12-16 18:12       ` vcaputo
2017-12-17  7:09         ` Avi Kivity
2017-12-18  3:28     ` Goldwyn Rodrigues
2017-12-18  7:38       ` Avi Kivity

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