Re: [Qemu-devel] [PATCH 1/2] hw/9pfs: Add new virtfs option cache=writethrough to skip host page cache

[Stefan Hajnoczi]

On Fri, Oct 7, 2011 at 7:46 AM, Aneesh Kumar K.V
<address@hidden> wrote:
> cache=writethrough implies the file are opened in the host with O_SYNC open 
> flag
>
> Signed-off-by: Aneesh Kumar K.V <address@hidden>
> ---
>  fsdev/file-op-9p.h         |    1 +
>  fsdev/qemu-fsdev.c         |   10 ++++++++--
>  fsdev/qemu-fsdev.h         |    2 ++
>  hw/9pfs/virtio-9p-device.c |    5 +++++
>  hw/9pfs/virtio-9p.c        |   24 ++++++++++++++++++------
>  qemu-config.c              |    6 ++++++
>  qemu-options.hx            |   17 ++++++++++++-----
>  vl.c                       |    6 ++++++
>  8 files changed, 58 insertions(+), 13 deletions(-)

When would this be used?  For serving up vanilla 9P?

I think 9P.u and 9P.l have support for fsync(2) while vanilla 9P does not.

Stefan