Merge branch 'net-nsid-interpretation'

Nicolas Dichtel says:

====================
Ease to interpret net-nsid

The goal of this series is to ease the interpretation of nsid received in
netlink messages from other netns (when the user uses
NETLINK_F_LISTEN_ALL_NSID).

After this series, with a patched iproute2:

$ ip netns add foo
$ ip netns add bar
$ touch /var/run/netns/init_net
$ mount --bind /proc/1/ns/net /var/run/netns/init_net
$ ip netns set init_net 11
$ ip netns set foo 12
$ ip netns set bar 13
$ ip netns
init_net (id: 11)
bar (id: 13)
foo (id: 12)
$ ip -n foo netns set init_net 21
$ ip -n foo netns set foo 22
$ ip -n foo netns set bar 23
$ ip -n foo netns
init_net (id: 21)
bar (id: 23)
foo (id: 22)
$ ip -n bar netns set init_net 31
$ ip -n bar netns set foo 32
$ ip -n bar netns set bar 33
$ ip -n bar netns
init_net (id: 31)
bar (id: 33)
foo (id: 32)
$ ip netns list-id target-nsid 12
nsid 21 current-nsid 11 (iproute2 netns name: init_net)
nsid 22 current-nsid 12 (iproute2 netns name: foo)
nsid 23 current-nsid 13 (iproute2 netns name: bar)
$ ip -n bar netns list-id target-nsid 32 nsid 31
nsid 21 current-nsid 31 (iproute2 netns name: init_net)

v3 -> v4:
  - patch 5/5: fix imbalance lock in error path

v2 -> v3:
  - patch 5/5: account NETNSA_CURRENT_NSID in rtnl_net_get_size()

v1 -> v2:
  - patch 1/5: remove net from struct rtnl_net_dump_cb
  - patch 2/5: new in this version
  - patch 3/5: use a bool to know if rtnl_get_net_ns_capable() was called
  - patch 5/5: use struct net_fill_args
====================

Signed-off-by: David S. Miller <davem@davemloft.net>