[PATCH] remove swapper_inode

By moving the special-casing for swapper_space out of __mark_inode_dirty()
and into __set_page_dirty_nobuffers() we can remove swapper_inode.

fs/fs-writeback.c

@@ -49,9 +49,6 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 {
 	struct super_block *sb = inode->i_sb;
 
-	if (!sb)
-		return;		/* swapper_space */
-
 	/*
 	 * Don't do this for I_DIRTY_PAGES - that doesn't actually
 	 * dirty the inode itself
@@ -90,9 +87,12 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 		 * Only add valid (hashed) inodes to the superblock's
 		 * dirty list.  Add blockdev inodes as well.
 		 */
-		if ((hlist_unhashed(&inode->i_hash) || (inode->i_state & (I_FREEING|I_CLEAR)))
-		    && !S_ISBLK(inode->i_mode))
-			goto out;
+		if (!S_ISBLK(inode->i_mode)) {
+			if (hlist_unhashed(&inode->i_hash))
+				goto out;
+			if (inode->i_state & (I_FREEING|I_CLEAR))
+				goto out;
+		}
 
 		/*
 		 * If the inode was already on s_dirty or s_io, don't

mm/page-writeback.c

@@ -516,7 +516,9 @@ int __set_page_dirty_nobuffers(struct page *page)
 				list_add(&page->list, &mapping->dirty_pages);
 			}
 			spin_unlock(&mapping->page_lock);
-			__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+			if (!PageSwapCache(page))
+				__mark_inode_dirty(mapping->host,
+							I_DIRTY_PAGES);
 		}
 	}
 	return ret;

mm/swap_state.c

@@ -16,14 +16,6 @@
 
 #include <asm/pgtable.h>
 
-/*
- * swapper_inode doesn't do anything much.  It is really only here to
- * avoid some special-casing in other parts of the kernel.
- */
-static struct inode swapper_inode = {
-	.i_mapping	= &swapper_space,
-};
-
 static struct backing_dev_info swap_backing_dev_info = {
 	.ra_pages	= 0,	/* No readahead */
 	.memory_backed	= 1,	/* Does not contribute to dirty memory */
@@ -38,7 +30,6 @@ struct address_space swapper_space = {
 	.dirty_pages	= LIST_HEAD_INIT(swapper_space.dirty_pages),
 	.io_pages	= LIST_HEAD_INIT(swapper_space.io_pages),
 	.locked_pages	= LIST_HEAD_INIT(swapper_space.locked_pages),
-	.host		= &swapper_inode,
 	.a_ops		= &swap_aops,
 	.backing_dev_info = &swap_backing_dev_info,
 	.i_mmap		= LIST_HEAD_INIT(swapper_space.i_mmap),