[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>

13 files changed, 16 insertions, 67 deletions

diff --git a/arch/s390/appldata/appldata_mem.c b/arch/s390/appldata/appldata_mem.c
index 7915a197d96d..180ba79a6267 100644
--- a/arch/s390/appldata/appldata_mem.c
+++ b/arch/s390/appldata/appldata_mem.c
@@ -130,7 +130,8 @@ static void appldata_get_mem_data(void *data)
         mem_data->totalhigh = P2K(val.totalhigh);
         mem_data->freehigh  = P2K(val.freehigh);
         mem_data->bufferram = P2K(val.bufferram);
-        mem_data->cached    = P2K(atomic_read(&nr_pagecache) - val.bufferram);
+        mem_data->cached    = P2K(global_page_state(NR_FILE_PAGES)
+                                - val.bufferram);
 
         si_swapinfo(&val);
         mem_data->totalswap = P2K(val.totalswap);
diff --git a/arch/sparc/kernel/sys_sunos.c b/arch/sparc/kernel/sys_sunos.c
index 288de276d9ff..aa0fb2efb615 100644
--- a/arch/sparc/kernel/sys_sunos.c
+++ b/arch/sparc/kernel/sys_sunos.c
@@ -196,7 +196,7 @@ asmlinkage int sunos_brk(unsigned long brk)
          * 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;
diff --git a/arch/sparc64/kernel/sys_sunos32.c b/arch/sparc64/kernel/sys_sunos32.c
index ae5b32f817f0..87ebdf858a3a 100644
--- a/arch/sparc64/kernel/sys_sunos32.c
+++ b/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;
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 8b1232320a99..ae9e3fea4b31 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -69,6 +69,7 @@ static ssize_t node_read_meminfo(struct sys_device * dev, char * buf)
                        "Node %d LowFree:      %8lu kB\n"
                        "Node %d Dirty:        %8lu kB\n"
                        "Node %d Writeback:    %8lu kB\n"
+                       "Node %d FilePages:    %8lu kB\n"
                        "Node %d Mapped:       %8lu kB\n"
                        "Node %d Slab:         %8lu kB\n",
                        nid, K(i.totalram),
@@ -82,6 +83,7 @@ static ssize_t node_read_meminfo(struct sys_device * dev, char * buf)
                        nid, K(i.freeram - i.freehigh),
                        nid, K(ps.nr_dirty),
                        nid, K(ps.nr_writeback),
+                       nid, K(node_page_state(nid, NR_FILE_PAGES)),
                        nid, K(node_page_state(nid, NR_FILE_MAPPED)),
                        nid, K(ps.nr_slab));
         n += hugetlb_report_node_meminfo(nid, buf + n);
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index bc7d9abca743..1af12fd77fe6 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -142,7 +142,8 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
         allowed = ((totalram_pages - hugetlb_total_pages())
                 * sysctl_overcommit_ratio / 100) + total_swap_pages;
 
-        cached = get_page_cache_size() - total_swapcache_pages - i.bufferram;
+        cached = global_page_state(NR_FILE_PAGES) -
+                        total_swapcache_pages - i.bufferram;
         if (cached < 0)
                 cached = 0;
 
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index eb42c1277023..08be91e6cecf 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -49,7 +49,7 @@ struct zone_padding {
 enum zone_stat_item {
         NR_FILE_MAPPED, /* mapped into pagetables.
                            only modified from process context */
-
+        NR_FILE_PAGES,
         NR_VM_ZONE_STAT_ITEMS };
 
 struct per_cpu_pages {
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 1245df7141aa..0a2f5d27f60e 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -113,51 +113,6 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 extern void remove_from_page_cache(struct page *page);
 extern void __remove_from_page_cache(struct page *page);
 
-extern atomic_t nr_pagecache;
-
-#ifdef CONFIG_SMP
-
-#define PAGECACHE_ACCT_THRESHOLD        max(16, NR_CPUS * 2)
-DECLARE_PER_CPU(long, nr_pagecache_local);
-
-/*
- * pagecache_acct implements approximate accounting for pagecache.
- * vm_enough_memory() do not need high accuracy. Writers will keep
- * an offset in their per-cpu arena and will spill that into the
- * global count whenever the absolute value of the local count
- * exceeds the counter's threshold.
- *
- * MUST be protected from preemption.
- * current protection is mapping->page_lock.
- */
-static inline void pagecache_acct(int count)
-{
-        long *local;
-
-        local = &__get_cpu_var(nr_pagecache_local);
-        *local += count;
-        if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) {
-                atomic_add(*local, &nr_pagecache);
-                *local = 0;
-        }
-}
-
-#else
-
-static inline void pagecache_acct(int count)
-{
-        atomic_add(count, &nr_pagecache);
-}
-#endif
-
-static inline unsigned long get_page_cache_size(void)
-{
-        int ret = atomic_read(&nr_pagecache);
-        if (unlikely(ret < 0))
-                ret = 0;
-        return ret;
-}
-
 /*
  * Return byte-offset into filesystem object for page.
  */
diff --git a/mm/filemap.c b/mm/filemap.c
index 648f2c0c8e18..87d62c44c3f0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -120,7 +120,7 @@ void __remove_from_page_cache(struct page *page)
         radix_tree_delete(&mapping->page_tree, page->index);
         page->mapping = NULL;
         mapping->nrpages--;
-        pagecache_acct(-1);
+        __dec_zone_page_state(page, NR_FILE_PAGES);
 }
 
 void remove_from_page_cache(struct page *page)
@@ -449,7 +449,7 @@ int add_to_page_cache(struct page *page, struct address_space *mapping,
                         page->mapping = mapping;
                         page->index = offset;
                         mapping->nrpages++;
-                        pagecache_acct(1);
+                        __inc_zone_page_state(page, NR_FILE_PAGES);
                 }
                 write_unlock_irq(&mapping->tree_lock);
                 radix_tree_preload_end();
diff --git a/mm/mmap.c b/mm/mmap.c
index 6446c6134b04..c1868ecdbc5f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -96,7 +96,7 @@ int __vm_enough_memory(long pages, int cap_sys_admin)
         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
                 unsigned long n;
 
-                free = get_page_cache_size();
+                free = global_page_state(NR_FILE_PAGES);
                 free += nr_swap_pages;
 
                 /*
diff --git a/mm/nommu.c b/mm/nommu.c
index 029fadac0fb5..5151c44a8257 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1122,7 +1122,7 @@ int __vm_enough_memory(long pages, int cap_sys_admin)
         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
                 unsigned long n;
 
-                free = get_page_cache_size();
+                free = global_page_state(NR_FILE_PAGES);
                 free += nr_swap_pages;
 
                 /*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 04dd2b01b2b7..8350720f98a8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2124,16 +2124,11 @@ static int page_alloc_cpu_notify(struct notifier_block *self,
                                  unsigned long action, void *hcpu)
 {
         int cpu = (unsigned long)hcpu;
-        long *count;
         unsigned long *src, *dest;
 
         if (action == CPU_DEAD) {
                 int i;
 
-                /* Drain local pagecache count. */
-                count = &per_cpu(nr_pagecache_local, cpu);
-                atomic_add(*count, &nr_pagecache);
-                *count = 0;
                 local_irq_disable();
                 __drain_pages(cpu);
 
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 7535211bb495..fccbd9bba77b 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -87,7 +87,7 @@ static int __add_to_swap_cache(struct page *page, swp_entry_t entry,
                         SetPageSwapCache(page);
                         set_page_private(page, entry.val);
                         total_swapcache_pages++;
-                        pagecache_acct(1);
+                        __inc_zone_page_state(page, NR_FILE_PAGES);
                 }
                 write_unlock_irq(&swapper_space.tree_lock);
                 radix_tree_preload_end();
@@ -132,7 +132,7 @@ void __delete_from_swap_cache(struct page *page)
         set_page_private(page, 0);
         ClearPageSwapCache(page);
         total_swapcache_pages--;
-        pagecache_acct(-1);
+        __dec_zone_page_state(page, NR_FILE_PAGES);
         INC_CACHE_INFO(del_total);
 }
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 4800091c129a..f16b33eb6d5c 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -20,12 +20,6 @@
  */
 DEFINE_PER_CPU(struct page_state, page_states) = {0};
 
-atomic_t nr_pagecache = ATOMIC_INIT(0);
-EXPORT_SYMBOL(nr_pagecache);
-#ifdef CONFIG_SMP
-DEFINE_PER_CPU(long, nr_pagecache_local) = 0;
-#endif
-
 static void __get_page_state(struct page_state *ret, int nr, cpumask_t *cpumask)
 {
         unsigned cpu;
@@ -402,6 +396,7 @@ struct seq_operations fragmentation_op = {
 static char *vmstat_text[] = {
         /* Zoned VM counters */
         "nr_mapped",
+        "nr_file_pages",
 
         /* Page state */
         "nr_dirty",