Re: [Qemu-devel] [PATCH v2 4/4] 9pfs: introduce init_out/in_iov_from_pdu

[Greg Kurz <groug@kaod.org>]

On Mon, 28 Nov 2016 13:27:24 -0800
Stefano Stabellini <sstabellini@kernel.org> wrote:

> Not all 9pfs transports share memory between request and response. For
> those who don't, it is necessary to know how much memory is required in
> the response.
> 
> Split the existing init_iov_from_pdu function in two:
> init_out_iov_from_pdu (for writes) and init_in_iov_from_pdu (for reads).
> init_in_iov_from_pdu takes an additional size parameter to specify the
> memory required for the response message.
> 
> Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
> ---

Reviewed-by: Greg Kurz <groug@kaod.org>

>  hw/9pfs/9p.c               |  6 +++++-
>  hw/9pfs/9p.h               |  6 ++++--
>  hw/9pfs/virtio-9p-device.c | 28 ++++++++++++++++++----------
>  3 files changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 79d7201..ce1f9d9 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1652,7 +1652,11 @@ static void v9fs_init_qiov_from_pdu(QEMUIOVector *qiov, V9fsPDU *pdu,
>      struct iovec *iov;
>      unsigned int niov;
>  
> -    pdu->s->transport->init_iov_from_pdu(pdu, &iov, &niov, is_write);
> +    if (is_write) {
> +        pdu->s->transport->init_out_iov_from_pdu(pdu, &iov, &niov);
> +    } else {
> +        pdu->s->transport->init_in_iov_from_pdu(pdu, &iov, &niov, size);
> +    }
>  
>      qemu_iovec_init_external(&elem, iov, niov);
>      qemu_iovec_init(qiov, niov);
> diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
> index c8c9aa8..4c4feaf 100644
> --- a/hw/9pfs/9p.h
> +++ b/hw/9pfs/9p.h
> @@ -349,8 +349,10 @@ struct V9fsTransport {
>                                  va_list ap);
>      ssize_t     (*pdu_vunmarshal)(V9fsPDU *pdu, size_t offset, const char *fmt,
>                                    va_list ap);
> -    void        (*init_iov_from_pdu)(V9fsPDU *pdu, struct iovec **piov,
> -                                     unsigned int *pniov, bool is_write);
> +    void        (*init_in_iov_from_pdu)(V9fsPDU *pdu, struct iovec **piov,
> +                                        unsigned int *pniov, size_t size);
> +    void        (*init_out_iov_from_pdu)(V9fsPDU *pdu, struct iovec **piov,
> +                                         unsigned int *pniov);
>      void        (*push_and_notify)(V9fsPDU *pdu);
>  };
>  
> diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
> index 273425b..27a4a32 100644
> --- a/hw/9pfs/virtio-9p-device.c
> +++ b/hw/9pfs/virtio-9p-device.c
> @@ -171,26 +171,34 @@ static ssize_t virtio_pdu_vunmarshal(V9fsPDU *pdu, size_t offset,
>      return v9fs_iov_vunmarshal(elem->out_sg, elem->out_num, offset, 1, fmt, ap);
>  }
>  
> -static void virtio_init_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
> -                                     unsigned int *pniov, bool is_write)
> +/* The size parameter is used by other transports. Do not drop it. */
> +static void virtio_init_in_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
> +                                        unsigned int *pniov, size_t size)
>  {
>      V9fsState *s = pdu->s;
>      V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
>      VirtQueueElement *elem = v->elems[pdu->idx];
>  
> -    if (is_write) {
> -        *piov = elem->out_sg;
> -        *pniov = elem->out_num;
> -    } else {
> -        *piov = elem->in_sg;
> -        *pniov = elem->in_num;
> -    }
> +    *piov = elem->in_sg;
> +    *pniov = elem->in_num;
> +}
> +
> +static void virtio_init_out_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
> +                                         unsigned int *pniov)
> +{
> +    V9fsState *s = pdu->s;
> +    V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
> +    VirtQueueElement *elem = v->elems[pdu->idx];
> +
> +    *piov = elem->out_sg;
> +    *pniov = elem->out_num;
>  }
>  
>  static const struct V9fsTransport virtio_9p_transport = {
>      .pdu_vmarshal = virtio_pdu_vmarshal,
>      .pdu_vunmarshal = virtio_pdu_vunmarshal,
> -    .init_iov_from_pdu = virtio_init_iov_from_pdu,
> +    .init_in_iov_from_pdu = virtio_init_in_iov_from_pdu,
> +    .init_out_iov_from_pdu = virtio_init_out_iov_from_pdu,
>      .push_and_notify = virtio_9p_push_and_notify,
>  };
>