To help developers and applications gain visibility into writeback
behaviour adding two entries to vm_stat_items and /proc/vmstat.  This will
allow us to track the "written" and "dirtied" counts.
   # grep nr_dirtied /proc/vmstat
   nr_dirtied 3747
   # grep nr_written /proc/vmstat
   nr_written 3618
Signed-off-by: Michael Rubin <mrubin@google.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
        NR_ISOLATED_ANON,       /* Temporary isolated pages from anon lru */
        NR_ISOLATED_FILE,       /* Temporary isolated pages from file lru */
        NR_SHMEM,               /* shmem pages (included tmpfs/GEM pages) */
+       NR_DIRTIED,             /* page dirtyings since bootup */
+       NR_WRITTEN,             /* page writings since bootup */
 #ifdef CONFIG_NUMA
        NUMA_HIT,               /* allocated in intended node */
        NUMA_MISS,              /* allocated in non intended node */
 
 {
        if (mapping_cap_account_dirty(mapping)) {
                __inc_zone_page_state(page, NR_FILE_DIRTY);
+               __inc_zone_page_state(page, NR_DIRTIED);
                __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
                task_dirty_inc(current);
                task_io_account_write(PAGE_CACHE_SIZE);
 void account_page_writeback(struct page *page)
 {
        inc_zone_page_state(page, NR_WRITEBACK);
+       inc_zone_page_state(page, NR_WRITTEN);
 }
 EXPORT_SYMBOL(account_page_writeback);
 
 
        "nr_isolated_anon",
        "nr_isolated_file",
        "nr_shmem",
+       "nr_dirtied",
+       "nr_written",
+
 #ifdef CONFIG_NUMA
        "numa_hit",
        "numa_miss",