From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alasdair G Kergon <agk@redhat.com>
Subject: Re: Re: [RFD] BIO_RW_BARRIER - what it means for devices,
	filesystems, and dm/md.
Date: Wed, 30 May 2007 11:41:15 +0100
Message-ID: <20070530104115.GO25091@agk.fab.redhat.com>
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Cc: Tejun Heo <htejun@gmail.com>, Stefan Bader <sbader3@googlemail.com>, David Chinner <dgc@sgi.com>, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Jens Axboe <jens.axboe@oracle.com>, linux-fsdevel@vger.kernel.org, Andreas Dilger <adilger@clusterfs.com>
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On Wed, May 30, 2007 at 11:12:37AM +0200, Stefan Bader wrote:
> it might be better to indicate -EOPNOTSUPP right from
> device-mapper.
 
Indeed we should.  For support, on receipt of a barrier, dm core should
send a zero-length barrier to all active underlying paths, and delay
mapping any further I/O.

Alasdair
-- 
agk@redhat.com