Re: [Qemu-devel] [PATCH COLO-Frame v16 33/35] COLO/filter: add each netdev a buffer filter

[Jason Wang <jasowang@redhat.com>]

On 04/08/2016 02:26 PM, zhanghailiang wrote:
> For COLO periodic mode, it need to buffer packets that
> sent by VM, and we will not release these packets until
> finish a checkpoint.
>
> Here, we add each netdev a buffer-filter that will be controlled
> by COLO. It is disabled by default, and the packets will not pass
> through these filters. If users don't enable COLO while configure
> qemu, these buffer-filters will not be added.
>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Yang Hongyang <hongyang.yang@easystack.cn>
> ---
> v16:
> - Remove the useless check in colo_add_buffer_filter()
> v15:
> - call object_new_with_props() directly to add filter in
>   colo_add_buffer_filter. (Jason's suggestion)
> v14:
> - New patch
> ---
>  include/migration/colo.h |  2 ++
>  include/net/filter.h     |  2 ++
>  migration/colo-comm.c    |  7 +++++++
>  migration/colo.c         | 39 +++++++++++++++++++++++++++++++++++++++
>  net/filter-buffer.c      |  2 --
>  stubs/migration-colo.c   |  4 ++++
>  6 files changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/include/migration/colo.h b/include/migration/colo.h
> index 919b135..87ea6d2 100644
> --- a/include/migration/colo.h
> +++ b/include/migration/colo.h
> @@ -37,4 +37,6 @@ COLOMode get_colo_mode(void);
>  void colo_do_failover(MigrationState *s);
>  
>  bool colo_shutdown(void);
> +void colo_add_buffer_filter(Notifier *notifier, void *data);
> +
>  #endif
> diff --git a/include/net/filter.h b/include/net/filter.h
> index 0c4a2ea..817eaf4 100644
> --- a/include/net/filter.h
> +++ b/include/net/filter.h
> @@ -21,6 +21,8 @@
>  #define NETFILTER_CLASS(klass) \
>      OBJECT_CLASS_CHECK(NetFilterClass, (klass), TYPE_NETFILTER)
>  
> +#define TYPE_FILTER_BUFFER "filter-buffer"
> +
>  typedef void (FilterSetup) (NetFilterState *nf, Error **errp);
>  typedef void (FilterCleanup) (NetFilterState *nf);
>  /*
> diff --git a/migration/colo-comm.c b/migration/colo-comm.c
> index 716a4f7..a90f1cb 100644
> --- a/migration/colo-comm.c
> +++ b/migration/colo-comm.c
> @@ -14,12 +14,14 @@
>  #include "qemu/osdep.h"
>  #include <migration/colo.h>
>  #include "trace.h"
> +#include <net/net.h>
>  
>  typedef struct {
>       bool colo_requested;
>  } COLOInfo;
>  
>  static COLOInfo colo_info;
> +static Notifier netdev_init_notifier;
>  
>  COLOMode get_colo_mode(void)
>  {
> @@ -59,6 +61,11 @@ static const VMStateDescription colo_state = {
>  void colo_info_init(void)
>  {
>      vmstate_register(NULL, 0, &colo_state, &colo_info);
> +    /* FIXME: Remove this after COLO switch to using colo-proxy */
> +    if (colo_supported()) {
> +        netdev_init_notifier.notify = colo_add_buffer_filter;
> +        netdev_init_add_notifier(&netdev_init_notifier);
> +    }
>  }
>  
>  bool migration_incoming_enable_colo(void)
> diff --git a/migration/colo.c b/migration/colo.c
> index c16a7d7..7a60bc1 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -19,12 +19,23 @@
>  #include "qapi/error.h"
>  #include "migration/failover.h"
>  #include "qapi-event.h"
> +#include "net/net.h"
> +#include "net/filter.h"
> +#include "net/vhost_net.h"
>  
>  static bool vmstate_loading;
>  
>  /* colo buffer */
>  #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
>  
> +typedef struct COLOListNode {
> +    void *opaque;
> +    QLIST_ENTRY(COLOListNode) node;
> +} COLOListNode;
> +
> +static QLIST_HEAD(, COLOListNode) COLOBufferFilters =
> +    QLIST_HEAD_INITIALIZER(COLOBufferFilters);
> +
>  bool colo_supported(void)
>  {
>      return true;
> @@ -384,6 +395,34 @@ static int colo_prepare_before_save(MigrationState *s)
>      return ret;
>  }
>  
> +void colo_add_buffer_filter(Notifier *notifier, void *data)
> +{
> +    char *netdev_id = data;
> +    NetFilterState *nf;
> +    char filter_name[128];
> +    Object *filter;
> +    COLOListNode *filternode;
> +
> +    snprintf(filter_name, sizeof(filter_name),
> +            "%scolo", netdev_id);
> +
> +    filter = object_new_with_props(TYPE_FILTER_BUFFER,
> +                        object_get_objects_root(),
> +                        filter_name, NULL,
> +                        "netdev", netdev_id,
> +                        "status", "off",
> +                        NULL);
> +    if (!filter) {
> +        return;

Looks like at least we need a warn here?

> +    }
> +    nf =  NETFILTER(filter);
> +    /* Only buffer the packets that sent out by VM */
> +    nf->direction = NET_FILTER_DIRECTION_RX;
> +    filternode = g_new0(COLOListNode, 1);
> +    filternode->opaque = nf;
> +    QLIST_INSERT_HEAD(&COLOBufferFilters, filternode, node);
> +}
> +
>  static void colo_process_checkpoint(MigrationState *s)
>  {
>      QEMUSizedBuffer *buffer = NULL;
> diff --git a/net/filter-buffer.c b/net/filter-buffer.c
> index 346306a..d1cf595 100644
> --- a/net/filter-buffer.c
> +++ b/net/filter-buffer.c
> @@ -17,8 +17,6 @@
>  #include "qapi-visit.h"
>  #include "qom/object.h"
>  
> -#define TYPE_FILTER_BUFFER "filter-buffer"
> -
>  #define FILTER_BUFFER(obj) \
>      OBJECT_CHECK(FilterBufferState, (obj), TYPE_FILTER_BUFFER)
>  
> diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
> index e507e17..65b1f49 100644
> --- a/stubs/migration-colo.c
> +++ b/stubs/migration-colo.c
> @@ -49,3 +49,7 @@ bool colo_shutdown(void)
>  {
>      return false;
>  }
> +
> +void colo_add_buffer_filter(Notifier *notifier, void *data)
> +{
> +}