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Date: Wed, 14 Jan 2009 09:34:55 -0500
From: Theodore Tso <tytso@MIT.EDU>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Jan Kara <jack@suse.cz>,
       Fernando Luis =?iso-8859-1?Q?V=E1zquez?= Cao 
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       Alan Cox <alan@lxorguk.ukuu.org.uk>, Pavel Machek <pavel@suse.cz>,
       kernel list <linux-kernel@vger.kernel.org>, sandeen@redhat.com
Subject: Re: ext2 + -osync: not as easy as it seems
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On Wed, Jan 14, 2009 at 03:08:04PM +0100, Jens Axboe wrote:
> 
> It also guarentees that when you get a completion for that barrier
> write, it's on safe storage. Think of it as a flush-write-flush
> operation, in the presence of write back caching.
> 

Is that true even if the barrier isn't attached to a write operation,
i.e., when using

      blkdev_issue_flush(sb, NULL);

?

					- Ted