[PATCH] zoned vm counters: conversion of nr_pagecache to per zone counter

Currently a single atomic variable is used to establish the size of the page
cache in the whole machine.  The zoned VM counters have the same method of
implementation as the nr_pagecache code but also allow the determination of
the pagecache size per zone.

Remove the special implementation for nr_pagecache and make it a zoned counter
named NR_FILE_PAGES.

Updates of the page cache counters are always performed with interrupts off.
We can therefore use the __ variant here.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/sparc64/kernel/sys_sunos32.c

@@ -155,7 +155,7 @@ asmlinkage int sunos_brk(u32 baddr)
 	 * simple, it hopefully works in most obvious cases.. Easy to
 	 * fool it, but this should catch most mistakes.
 	 */
-	freepages = get_page_cache_size();
+	freepages = global_page_state(NR_FILE_PAGES);
 	freepages >>= 1;
 	freepages += nr_free_pages();
 	freepages += nr_swap_pages;