docker iotop :OSError: Netlink error: No such file or directory

在容器内使用iotop ，错误信息：

raceback (most recent call last):
File "/usr/sbin/iotop", line 16, in <module>
main()
File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 559, in main
main_loop()
File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 549, in <lambda>
main_loop = lambda: run_iotop(options)
File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 447, in run_iotop
return curses.wrapper(run_iotop_window, options)
File "/usr/lib64/python2.6/curses/wrapper.py", line 43, in wrapper
return func(stdscr, *args, **kwds)
File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 437, in run_iotop_window
taskstats_connection = TaskStatsNetlink(options)
File "/usr/lib/python2.6/site-packages/iotop/data.py", line 113, in __init__
self.family_id = controller.get_family_id('TASKSTATS')
File "/usr/lib/python2.6/site-packages/iotop/genetlink.py", line 54, in get_family_id
m = self.conn.recv()
File "/usr/lib/python2.6/site-packages/iotop/netlink.py", line 190, in recv
raise err
OSError: Netlink error: No such file or directory (2)

iotop是通过内核的taskstats接口获取统计信息的。taskstats是基于generic netlink实现的，而且taskstats不支持net namespace。

static struct genl_family family = {
.id		= GENL_ID_GENERATE,
.name		= TASKSTATS_GENL_NAME,
.version	= TASKSTATS_GENL_VERSION,
.maxattr	= TASKSTATS_CMD_ATTR_MAX,
};

static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
{
int i, n = 0;
struct genl_family *rt;
struct net *net = sock_net(skb->sk);
int chains_to_skip = cb->args[0];
int fams_to_skip = cb->args[1];
for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
n = 0;
list_for_each_entry(rt, genl_family_chain(i), family_list) {
if (!rt->netnsok && !net_eq(net, &init_net))///don't support netnamespace
continue;