From: Christoph Hellwig <hch@lst.de>
To: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Cc: Christoph Hellwig <hch@lst.de>, Jan Kara <jack@suse.cz>,
jaxboe@fusionio.com, tj@kernel.org, James.Bottomley@suse.de,
linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org,
tytso@mit.edu, chris.mason@oracle.com, swhiteho@redhat.com,
konishi.ryusuke@lab.ntt.co.jp, dm-devel@redhat.com,
linux-raid@vger.kernel.org
Subject: Re: [PATCH, RFC 2/2] dm: support REQ_FLUSH directly
Date: Wed, 4 Aug 2010 10:54:23 +0200 [thread overview]
Message-ID: <20100804085423.GA15687@lst.de> (raw)
In-Reply-To: <4C58F341.9060605@ct.jp.nec.com>
On Wed, Aug 04, 2010 at 01:57:37PM +0900, Kiyoshi Ueda wrote:
> > - if (unlikely(dm_rq_is_flush_request(rq))) {
> > + if (rq->cmd_flags & REQ_FLUSH) {
> > BUG_ON(md->flush_request);
> > md->flush_request = rq;
> > blk_start_request(rq);
>
> Current request-based device-mapper's flush code depends on
> the block-layer's barrier behavior which dispatches only one request
> at a time when flush is needed.
> In other words, current request-based device-mapper can't handle
> other requests while a flush request is in progress.
>
> I'll take a look how I can fix the request-based device-mapper to
> cope with it. I think it'll take time for carefull investigation.
Given that request based device mapper doesn't even look at the
block numbers from what I can see just removing any special casing
for REQ_FLUSH should probably do it.
next prev parent reply other threads:[~2010-08-04 8:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20100727165627.GA474@lst.de>
[not found] ` <20100727175418.GF6820@quack.suse.cz>
[not found] ` <20100803184939.GA12198@lst.de>
[not found] ` <20100803185148.GA12258@lst.de>
2010-08-04 4:57 ` [PATCH, RFC 2/2] dm: support REQ_FLUSH directly Kiyoshi Ueda
2010-08-04 8:54 ` Christoph Hellwig [this message]
2010-08-05 2:16 ` Jun'ichi Nomura
2010-08-26 22:50 ` Mike Snitzer
2010-08-27 0:40 ` Mike Snitzer
2010-08-27 1:20 ` Jamie Lokier
2010-08-27 1:43 ` Jun'ichi Nomura
2010-08-27 4:08 ` Mike Snitzer
2010-08-27 5:52 ` Jun'ichi Nomura
2010-08-27 14:13 ` Mike Snitzer
2010-08-30 4:45 ` Jun'ichi Nomura
2010-08-30 8:33 ` Tejun Heo
2010-08-30 12:43 ` Mike Snitzer
2010-08-30 12:45 ` Tejun Heo
2010-08-06 16:04 ` [PATCH, RFC] relaxed barriers Tejun Heo
2010-08-06 23:34 ` Christoph Hellwig
2010-08-07 10:13 ` [PATCH REPOST " Tejun Heo
2010-08-08 14:31 ` Christoph Hellwig
2010-08-09 14:50 ` Tejun Heo
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