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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com,
	JBeulich@novell.com, jeremy.fitzhardinge@citrix.com,
	axboe@kernel.dk
Subject: Re: [PATCH 1/3] xen/blk[front|back]: Use the full FLUSH | FUA instead of just FLUSH.
Date: Sat, 10 Sep 2011 20:33:06 -0400	[thread overview]
Message-ID: <20110911003306.GB9989@oracle.com> (raw)
In-Reply-To: <20110910180849.GA6621@infradead.org>

On Sat, Sep 10, 2011 at 02:08:49PM -0400, Christoph Hellwig wrote:
> On Fri, Sep 09, 2011 at 02:30:59PM -0400, Konrad Rzeszutek Wilk wrote:
> > During a FLUSH we can pass sector number that we want to
> > have flushed - which is what FUA requests are.
> 
> No, that is not the case.
> 
> REQ_FLUSH without data		-> pure flush
> REQ_FLUSH with data		-> preflush plus write

Excellent. So we have been doing it right all along.

> REQ_FUA				-> write and ranged postflush

Ah, somehow I was thinking that you can't write data with a
REQ_FLUSH, but that is nonsense as the block/blk-flush.c
explains in great details.

Will drop this patch - and thanks for clarifying it!

WARNING: multiple messages have this Message-ID (diff)
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: axboe@kernel.dk, xen-devel@lists.xensource.com,
	linux-kernel@vger.kernel.org, JBeulich@novell.com,
	jeremy.fitzhardinge@citrix.com
Subject: Re: [PATCH 1/3] xen/blk[front|back]: Use the full FLUSH | FUA instead of just FLUSH.
Date: Sat, 10 Sep 2011 20:33:06 -0400	[thread overview]
Message-ID: <20110911003306.GB9989@oracle.com> (raw)
In-Reply-To: <20110910180849.GA6621@infradead.org>

On Sat, Sep 10, 2011 at 02:08:49PM -0400, Christoph Hellwig wrote:
> On Fri, Sep 09, 2011 at 02:30:59PM -0400, Konrad Rzeszutek Wilk wrote:
> > During a FLUSH we can pass sector number that we want to
> > have flushed - which is what FUA requests are.
> 
> No, that is not the case.
> 
> REQ_FLUSH without data		-> pure flush
> REQ_FLUSH with data		-> preflush plus write

Excellent. So we have been doing it right all along.

> REQ_FUA				-> write and ranged postflush

Ah, somehow I was thinking that you can't write data with a
REQ_FLUSH, but that is nonsense as the block/blk-flush.c
explains in great details.

Will drop this patch - and thanks for clarifying it!

  reply	other threads:[~2011-09-11  0:34 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-09 18:30 [PATCH] xen-blk[front|back] FUA additions Konrad Rzeszutek Wilk
2011-09-09 18:30 ` Konrad Rzeszutek Wilk
2011-09-09 18:30 ` [PATCH 1/3] xen/blk[front|back]: Use the full FLUSH | FUA instead of just FLUSH Konrad Rzeszutek Wilk
2011-09-10 18:08   ` Christoph Hellwig
2011-09-11  0:33     ` Konrad Rzeszutek Wilk [this message]
2011-09-11  0:33       ` Konrad Rzeszutek Wilk
2011-09-09 18:31 ` [PATCH 3/3] xen-blkfront: If no barrier or flush is supported, use invalid operation Konrad Rzeszutek Wilk
2011-09-12  8:01   ` Jan Beulich
2011-09-12  8:01     ` Jan Beulich
2011-09-16 19:15     ` [Xen-devel] " Konrad Rzeszutek Wilk
2011-09-19  9:35       ` Jan Beulich
2011-09-19  9:35         ` Jan Beulich

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