Re: [Qemu-devel] [PATCH -V2 4/6] hw/9pfs: Implement syncfs

[Stefan Hajnoczi]

On Tue, Mar 1, 2011 at 6:38 AM, Aneesh Kumar K.V
<address@hidden> wrote:
> Signed-off-by: Aneesh Kumar K.V <address@hidden>
> ---
>  hw/9pfs/virtio-9p.c |   31 +++++++++++++++++++++++++++++++
>  hw/9pfs/virtio-9p.h |    2 ++
>  2 files changed, 33 insertions(+), 0 deletions(-)
>
> diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
> index c4b0198..882f4f3 100644
> --- a/hw/9pfs/virtio-9p.c
> +++ b/hw/9pfs/virtio-9p.c
> @@ -1978,6 +1978,36 @@ static void v9fs_fsync(V9fsState *s, V9fsPDU *pdu)
>     v9fs_post_do_fsync(s, pdu, err);
>  }
>
> +static void v9fs_post_do_syncfs(V9fsState *s, V9fsPDU *pdu, int err)
> +{
> +    if (err == -1) {
> +        err = -errno;
> +    }
> +    complete_pdu(s, pdu, err);
> +}
> +
> +static void v9fs_syncfs(V9fsState *s, V9fsPDU *pdu)
> +{
> +    int err;
> +    int32_t fid;
> +    size_t offset = 7;
> +    V9fsFidState *fidp;
> +
> +    pdu_unmarshal(pdu, offset, "d", &fid);
> +    fidp = lookup_fid(s, fid);
> +    if (fidp == NULL) {
> +        err = -ENOENT;
> +        v9fs_post_do_syncfs(s, pdu, err);
> +        return;
> +    }
> +    /*
> +     * We don't have per file system syncfs
> +     * So just return success
> +     */
> +    err = 0;
> +    v9fs_post_do_syncfs(s, pdu, err);
> +}

Please explain the semantics of P9_TSYNCFS.  Won't returning success
without doing anything lead to data integrity issues?

It seems unnecessary to split v9fs_post_do_syncfs() into its own
function since there is no blocking point here and a callback will not
be needed.

Stefan