Lockd: make it network namespace aware

With this patch set Lockd will be able to handle lock requests from different
network namespaces separately.

Main ideas of the patch set are:

1) per-net Lockd users counter and resources.

2) nlmsvc_users counter become global one (equal to sum of all per-net
counters).

3) On lockd_up() call:
a) if nlmsvc_users if equal to 0, then lockd thread is started.
b) if current per-net counter equal to 0, then per-net resources are allocated
(lockd_up_net() function).
c) global and current net users counters are increased by one.

4) On lockd_down() call:
a) global and current net users counters are decreased by one.
b) if current per-net counter become equal to 0, then per-net resources are
allocated (lockd_down_net() function).
c) if nlmsvc_users become equal to 0, then lockd thread is stopped.

The following series consists of:

---

Stanislav Kinsbursky (6):
      Lockd: create permanent lockd sockets in current network namespace
      Lockd: pernet usage counter introduced
      Lockd: per-net up and down routines introduced
      LockD: make nlm hosts network namespace aware
      LockD: make NSM network namespace aware
      Lockd: shutdown NLM hosts in network namespace context


 fs/lockd/clntlock.c         |    3 +
 fs/lockd/host.c             |   42 ++++++++++++---
 fs/lockd/mon.c              |   13 +++--
 fs/lockd/netns.h            |   12 ++++
 fs/lockd/svc.c              |  117 +++++++++++++++++++++++++++++++++++++------
 fs/nfs/client.c             |    1 
 include/linux/lockd/bind.h  |    1 
 include/linux/lockd/lockd.h |    5 +-
 include/linux/sunrpc/svc.h  |    2 +
 net/sunrpc/svc.c            |    3 +
 10 files changed, 166 insertions(+), 33 deletions(-)
 create mode 100644 fs/lockd/netns.h