Re: [Qemu-devel] [PATCH v2] sheepdog: implement direct write semantics

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Jan 10, 2013 at 04:03:47PM +0800, Liu Yuan wrote:
> From: Liu Yuan <tailai.ly@taobao.com>
> 
> Sheepdog supports both writeback/writethrough write but has not yet supported
> DIRECTIO semantics which bypass the cache completely even if Sheepdog daemon is
> set up with cache enabled.
> 
> Suppose cache is enabled on Sheepdog daemon size, the new cache control is
> 
> cache=writeback # enable the writeback semantics for write
> cache=writethrough # enable the emulated writethrough semantics for write
> cache=directsync # disable cache competely
> 
> Guest WCE toggling on the run time to toggle writeback/writethrough is also
> supported.
> 
> Cc: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Stefan Hajnoczi <stefanha@gmail.com>
> Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
> ---
>  v2: adopt to current emulated writethrough cache setting
> 
>  block/sheepdog.c |   70 +++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 40 insertions(+), 30 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>