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From: "Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] [PATCH -V3 7/8] hw/9pfs: Add new virtfs option
	cache=none to skip host page cache
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Date: Mon, 14 Mar 2011 00:34:24 +0530
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org

On Sun, 13 Mar 2011 17:23:50 +0000, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> On Sat, Mar 5, 2011 at 5:52 PM, Aneesh Kumar K.V
> <aneesh.kumar@linux.vnet.ibm.com> wrote:
> > cache=none implies the file are opened in the host with O_SYNC open flag
> 
> O_SYNC does not bypass the host page cache.  It ensures that writes
> only complete once data has been written to the disk.
> 
> O_DIRECT is a hint to bypass the host page cache when possible.
> 
> A boolean on|off option would be nicer than an option that takes the
> special string "none".  For example, direct=on|off.  It also makes the
> code nicer by using bools instead of strdup strings that get leaked.
> 

What i wanted is the O_SYNC behavior. Well the comment should be updated. I
want to make sure that we don't have dirty data in host page cache after
a write. It is always good to make read hit the page cache

-aneesh