Re: [PATCH 3/5] block/nbd.c: Add yank feature

[Dr. David Alan Gilbert]

* Lukas Straub (address@hidden) wrote:
> Add yank option, pass it to the socket-channel and register a yank
> function which sets s->state = NBD_CLIENT_QUIT. This is the same
> behaviour as if an error occured.
> 
> Signed-off-by: Lukas Straub <address@hidden>

> +static void nbd_yank(void *opaque)
> +{
> +    BlockDriverState *bs = opaque;
> +    BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
> +
> +    atomic_set(&s->state, NBD_CLIENT_QUIT);

I think I was expecting a shutdown on the socket here - why doesn't it
have one?

Dave

> +}
> +
>  static void nbd_client_close(BlockDriverState *bs)
>  {
>      BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
> @@ -1407,14 +1421,17 @@ static void nbd_client_close(BlockDriverState *bs)
>      nbd_teardown_connection(bs);
>  }
>  
> -static QIOChannelSocket *nbd_establish_connection(SocketAddress *saddr,
> +static QIOChannelSocket *nbd_establish_connection(BlockDriverState *bs,
> +                                                  SocketAddress *saddr,
>                                                    Error **errp)
>  {
> +    BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
>      QIOChannelSocket *sioc;
>      Error *local_err = NULL;
>  
>      sioc = qio_channel_socket_new();
>      qio_channel_set_name(QIO_CHANNEL(sioc), "nbd-client");
> +    qio_channel_set_yank(QIO_CHANNEL(sioc), s->yank);
>  
>      qio_channel_socket_connect_sync(sioc, saddr, &local_err);
>      if (local_err) {
> @@ -1438,7 +1455,7 @@ static int nbd_client_connect(BlockDriverState *bs, 
> Error **errp)
>       * establish TCP connection, return error if it fails
>       * TODO: Configurable retry-until-timeout behaviour.
>       */
> -    QIOChannelSocket *sioc = nbd_establish_connection(s->saddr, errp);
> +    QIOChannelSocket *sioc = nbd_establish_connection(bs, s->saddr, errp);
>  
>      if (!sioc) {
>          return -ECONNREFUSED;
> @@ -1829,6 +1846,12 @@ static QemuOptsList nbd_runtime_opts = {
>                      "future requests before a successful reconnect will "
>                      "immediately fail. Default 0",
>          },
> +        {
> +            .name = "yank",
> +            .type = QEMU_OPT_BOOL,
> +            .help = "Forcibly close the connection and don't attempt to "
> +                    "reconnect when the 'yank' qmp command is executed.",
> +        },
>          { /* end of list */ }
>      },
>  };
> @@ -1888,6 +1911,8 @@ static int nbd_process_options(BlockDriverState *bs, 
> QDict *options,
>  
>      s->reconnect_delay = qemu_opt_get_number(opts, "reconnect-delay", 0);
>  
> +    s->yank = qemu_opt_get_bool(opts, "yank", false);
> +
>      ret = 0;
>  
>   error:
> @@ -1921,6 +1946,10 @@ static int nbd_open(BlockDriverState *bs, QDict 
> *options, int flags,
>      /* successfully connected */
>      s->state = NBD_CLIENT_CONNECTED;
>  
> +    if (s->yank) {
> +        yank_register_function(nbd_yank, bs);
> +    }
> +
>      s->connection_co = qemu_coroutine_create(nbd_connection_entry, s);
>      bdrv_inc_in_flight(bs);
>      aio_co_schedule(bdrv_get_aio_context(bs), s->connection_co);
> @@ -1972,6 +2001,11 @@ static void nbd_close(BlockDriverState *bs)
>      BDRVNBDState *s = bs->opaque;
>  
>      nbd_client_close(bs);
> +
> +    if (s->yank) {
> +        yank_unregister_function(nbd_yank, bs);
> +    }
> +
>      nbd_clear_bdrvstate(s);
>  }
>  
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 943df1926a..1c1578160e 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -3862,6 +3862,8 @@
>  #                   reconnect. After that time, any delayed requests and all
>  #                   future requests before a successful reconnect will
>  #                   immediately fail. Default 0 (Since 4.2)
> +# @yank: Forcibly close the connection and don't attempt to reconnect when
> +#        the 'yank' qmp command is executed. (Since: 5.1)
>  #
>  # Since: 2.9
>  ##
> @@ -3870,7 +3872,8 @@
>              '*export': 'str',
>              '*tls-creds': 'str',
>              '*x-dirty-bitmap': 'str',
> -            '*reconnect-delay': 'uint32' } }
> +            '*reconnect-delay': 'uint32',
> +         'yank': 'bool' } }
>  
>  ##
>  # @BlockdevOptionsRaw:
> -- 
> 2.20.1
> 


--
Dr. David Alan Gilbert / address@hidden / Manchester, UK