Add a dirty map to address spaces

In a NUMA system it is helpful to know where the dirty pages of a mapping
are located. That way we will be able to implement writeout for applications
that are constrained to a portion of the memory of the system (like f.e. done
through cpusets).

Signed-off-by; Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.20-rc3/fs/fs-writeback.c
===================================================================
--- linux-2.6.20-rc3.orig/fs/fs-writeback.c	2007-01-03 10:32:32.000000000 -0800
+++ linux-2.6.20-rc3/fs/fs-writeback.c	2007-01-03 11:23:20.000000000 -0800
@@ -223,11 +223,17 @@
 			/*
 			 * The inode is clean, inuse
 			 */
+#ifdef CONFIG_NUMA
+			inode->i_mapping->dirty_map = NODE_MASK_NONE;
+#endif
 			list_move(&inode->i_list, &inode_in_use);
 		} else {
 			/*
 			 * The inode is clean, unused
 			 */
+#ifdef CONFIG_NUMA
+			inode->i_mapping->dirty_map = NODE_MASK_NONE;
+#endif
 			list_move(&inode->i_list, &inode_unused);
 		}
 	}
Index: linux-2.6.20-rc3/fs/inode.c
===================================================================
--- linux-2.6.20-rc3.orig/fs/inode.c	2007-01-03 10:32:32.000000000 -0800
+++ linux-2.6.20-rc3/fs/inode.c	2007-01-03 10:41:42.000000000 -0800
@@ -147,6 +147,9 @@
 		mapping->flags = 0;
 		mapping_set_gfp_mask(mapping, GFP_HIGHUSER);
 		mapping->assoc_mapping = NULL;
+#ifdef CONFIG_NUMA
+		mapping->dirty_map = NODE_MASK_NONE;
+#endif
 		mapping->backing_dev_info = &default_backing_dev_info;
 
 		/*
Index: linux-2.6.20-rc3/include/linux/fs.h
===================================================================
--- linux-2.6.20-rc3.orig/include/linux/fs.h	2007-01-03 10:32:32.000000000 -0800
+++ linux-2.6.20-rc3/include/linux/fs.h	2007-01-03 10:41:42.000000000 -0800
@@ -446,6 +446,9 @@
 	spinlock_t		private_lock;	/* for use by the address_space */
 	struct list_head	private_list;	/* ditto */
 	struct address_space	*assoc_mapping;	/* ditto */
+#ifdef CONFIG_NUMA
+	nodemask_t		dirty_map;	/* Map of nodes with dirty pages */
+#endif
 } __attribute__((aligned(sizeof(long))));
 	/*
 	 * On most architectures that alignment is already the case; but
Index: linux-2.6.20-rc3/mm/page-writeback.c
===================================================================
--- linux-2.6.20-rc3.orig/mm/page-writeback.c	2007-01-03 10:32:32.000000000 -0800
+++ linux-2.6.20-rc3/mm/page-writeback.c	2007-01-03 11:21:40.000000000 -0800
@@ -813,6 +813,9 @@
 		if (!spd)
 			spd = __set_page_dirty_buffers;
 #endif
+#ifdef CONFIG_NUMA
+		node_set(page_to_nid(page), mapping->dirty_map);
+#endif
 		return (*spd)(page);
 	}
 	if (!PageDirty(page)) {