From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [PATCHSET block#for-2.6.36-post] block: replace barrier with
 sequenced flush
Date: Thu, 19 Aug 2010 11:57:53 +0200
Message-ID: <4C6D0021.4040601@kernel.org>
References: <1281616891-5691-1-git-send-email-tj@kernel.org> <20100818094620.GA14707@lst.de>
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Cc: jaxboe@fusionio.com, linux-fsdevel@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
	James.Bottomley@suse.de, tytso@mit.edu, chris.mason@oracle.com,
	swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp,
	dm-devel@redhat.com, vst@vlnb.net, jack@suse.cz,
	rwheeler@redhat.com, hare@suse.de
To: Christoph Hellwig <hch@lst.de>
Return-path: <linux-scsi-owner@vger.kernel.org>
In-Reply-To: <20100818094620.GA14707@lst.de>
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Hello,

On 08/18/2010 11:46 AM, Christoph Hellwig wrote:
> FYI: One issue with this series is that make_request based drivers
> not have to access all REQ_FLUSH and REQ_FUA requests.  We'll either
> need to add handling to empty REQ_FLUSH requests to all of them or
> figure out a way to prevent them getting sent.  That is assuming they'll
> simply ignore REQ_FLUSH/REQ_FUA on normal writes.

Can you be a bit more specific?  In most cases, request based drivers
should be fine.  They sit behind the front most request_queue which
would discompose REQ_FLUSH/FUAs into appropriate command sequence.
For the request based drivers, it's not different from the original
REQ_HARDBARRIER mechanism, it'll just see flushes and optionally FUA
writes.

Thanks.

-- 
tejun