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Date: Fri, 1 Jul 2016 07:04:55 +0200
From: Christoph Hellwig <hch@lst.de>
To: Damien Le Moal <Damien.LeMoal@hgst.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Amir Goldstein <amir73il@gmail.com>,
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Subject: Re: Question about loop device DIO/AIO and FLUSH
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On Fri, Jul 01, 2016 at 05:00:18AM +0000, Damien Le Moal wrote:
> Did you mean "...I/O requests that have already been fully submitted" ?

No.

> Flushing I/Os that have already completed does not seem
> to make much sense. Or I am also missing something...

With a volatile write cache this makes a lot of sense.  And fsync
flushes the volatile fs metadata to disk, while flush flushes the
volatile disk write cache.