Pidns: make full use of xxx_vnr() calls

Some time ago the xxx_vnr() calls (e.g.  pid_vnr or find_task_by_vpid) were
_all_ converted to operate on the current pid namespace.  After this each call
like xxx_nr_ns(foo, current->nsproxy->pid_ns) is nothing but a xxx_vnr(foo)
one.

Switch all the xxx_nr_ns() callers to use the xxx_vnr() calls where
appropriate.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Reviewed-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9dadc9d..89d963f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2488,7 +2488,7 @@
 	pid_t tmp;
 	int r;
 
-	tmp = pid_nr_ns(cad_pid, current->nsproxy->pid_ns);
+	tmp = pid_vnr(cad_pid);
 
 	r = __do_proc_dointvec(&tmp, table, write, filp, buffer,
 			       lenp, ppos, NULL, NULL);