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Date: Fri, 1 Jul 2016 06:25:10 +0200
From: Christoph Hellwig <hch@lst.de>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Ming Lei <ming.lei@canonical.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-block <linux-block@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@fb.com>
Subject: Re: Question about loop device DIO/AIO and FLUSH
Message-ID: <20160701042510.GA381@lst.de>
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On Thu, Jun 30, 2016 at 11:54:48PM +0300, Amir Goldstein wrote:
> Hi Ming,
> 
> I was reading through the code of loop DIO/AIO
> and I was wondering whether lo_req_flush() really
> honors REQ_FLUSH by calling  vfs_fsync() on a backing file
> that is open with O_DIRECT?
> 
> Shouldn't lo_req_flush() actually wait for completion of
> all the in-flight loop AIO requests to complete?
> Am I missing something?

Both fsync and flush semanrics only apply to I/O requests that have already
completed.