[PATCH] read_mapping_page for address space

Add read_mapping_page() which is used for callers that pass
mapping->a_ops->readpage as the filler for read_cache_page.  This removes
some duplication from filesystem code.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/hfsplus/bnode.c b/fs/hfsplus/bnode.c
index 746abc9..77bf434 100644
--- a/fs/hfsplus/bnode.c
+++ b/fs/hfsplus/bnode.c
@@ -440,7 +440,7 @@
 	block = off >> PAGE_CACHE_SHIFT;
 	node->page_offset = off & ~PAGE_CACHE_MASK;
 	for (i = 0; i < tree->pages_per_bnode; block++, i++) {
-		page = read_cache_page(mapping, block, (filler_t *)mapping->a_ops->readpage, NULL);
+		page = read_mapping_page(mapping, block, NULL);
 		if (IS_ERR(page))
 			goto fail;
 		if (PageError(page)) {