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Date: Fri, 22 Aug 2014 13:25:56 +0100
From: "Richard W.M. Jones" <rjones@redhat.com>
Message-ID: <20140822122556.GJ14001@redhat.com>
References: <cover.1405058453.git.hutao@cn.fujitsu.com>
	<20140728084846.GH31917@G08FNSTD100614.fnst.cn.fujitsu.com>
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In-Reply-To: <20140728084846.GH31917@G08FNSTD100614.fnst.cn.fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH v12 0/6] qcow2,
 raw: add preallocation=full and preallocation=falloc
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To: Hu Tao <hutao@cn.fujitsu.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Yasunori Goto <y-goto@jp.fujitsu.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Max Reitz <mreitz@redhat.com>


On Mon, Jul 28, 2014 at 04:48:46PM +0800, Hu Tao wrote:
> ping...
> 
> All the 6 patches have reviewed-by now.
> 
> On Fri, Jul 11, 2014 at 02:09:57PM +0800, Hu Tao wrote:
> > This series adds two preallocation mode to qcow2 and raw:
> > 
> > Option preallocation=full preallocates disk space for image by writing
> > zeros to disk, this ensures disk space in any cases.
> > 
> > Option preallocation=falloc preallocates disk space by calling
> > posix_fallocate(). This is faster than preallocation=full.

Sorry if this was discussed before, but why would anyone use
preallocation=full if preallocation=falloc was possible?

Shouldn't preallocation=full simply use posix_fallocate if it's
available, and fall back to writing zeroes if not?

Rich.

-- 
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