Re: [PATCH v8 3/4] vhost-user block device backend server

[Coiby Xu <coiby.xu@gmail.com>]

On Thu, Jun 11, 2020 at 04:24:52PM +0100, Stefan Hajnoczi wrote:
>On Fri, Jun 05, 2020 at 07:35:37AM +0800, Coiby Xu wrote:
>> +static void coroutine_fn vu_block_virtio_process_req(void *opaque)
>> +{
>> +    struct req_data *data = opaque;
>> +    VuServer *server = data->server;
>> +    VuVirtq *vq = data->vq;
>> +    VuVirtqElement *elem = data->elem;
>> +    uint32_t type;
>> +    VuBlockReq *req;
>> +
>> +    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
>> +    BlockBackend *backend = vdev_blk->backend;
>> +
>> +    struct iovec *in_iov = elem->in_sg;
>> +    struct iovec *out_iov = elem->out_sg;
>> +    unsigned in_num = elem->in_num;
>> +    unsigned out_num = elem->out_num;
>> +    /* refer to hw/block/virtio_blk.c */
>> +    if (elem->out_num < 1 || elem->in_num < 1) {
>> +        error_report("virtio-blk request missing headers");
>> +        free(elem);
>> +        return;
>> +    }
>> +
>> +    req = g_new0(VuBlockReq, 1);
>
>elem was allocated with enough space for VuBlockReq. Can this allocation
>be eliminated?
>
>  typedef struct VuBlockReq {
>-     VuVirtqElement *elem;
>+     VuVirtqElement elem;
>      int64_t sector_num;
>      size_t size;
>      struct virtio_blk_inhdr *in;
>      struct virtio_blk_outhdr out;
>      VuServer *server;
>      struct VuVirtq *vq;
>  } VuBlockReq;

Thank you for review this patch. Other issues for this patch have been
addressed in v9 except for this one. I'm not sure what you mean. I can't
find a way that doesn't require to allocate a VuBlockReq struct.


--
Best regards,
Coiby