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

This makes nr_dirty a per zone counter.  Looping over all processors is
avoided during writeback state determination.

The counter aggregation for nr_dirty had to be undone in the NFS layer since
we summed up the page counts from multiple zones.  Someone more familiar with
NFS should probably review what I have done.

[akpm@osdl.org: bugfix]
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>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 8fccb9c..a6d1ca5 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -497,7 +497,7 @@
 	nfs_list_add_request(req, &nfsi->dirty);
 	nfsi->ndirty++;
 	spin_unlock(&nfsi->req_lock);
-	inc_page_state(nr_dirty);
+	inc_zone_page_state(req->wb_page, NR_FILE_DIRTY);
 	mark_inode_dirty(inode);
 }
 
@@ -609,7 +609,6 @@
 	if (nfsi->ndirty != 0) {
 		res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
 		nfsi->ndirty -= res;
-		sub_page_state(nr_dirty,res);
 		if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
 			printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
 	}