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/fork.c b/kernel/fork.c
index ca54d97..31a2bad 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1488,13 +1488,7 @@
 	if (!IS_ERR(p)) {
 		struct completion vfork;
 
-		/*
-		 * this is enough to call pid_nr_ns here, but this if
-		 * improves optimisation of regular fork()
-		 */
-		nr = (clone_flags & CLONE_NEWPID) ?
-			task_pid_nr_ns(p, current->nsproxy->pid_ns) :
-				task_pid_vnr(p);
+		nr = task_pid_vnr(p);
 
 		if (clone_flags & CLONE_PARENT_SETTID)
 			put_user(nr, parent_tidptr);