[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/partitions/check.c b/fs/partitions/check.c
index 8851b81..cd885b2 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -499,8 +499,8 @@
 	struct address_space *mapping = bdev->bd_inode->i_mapping;
 	struct page *page;
 
-	page = read_cache_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
-			(filler_t *)mapping->a_ops->readpage, NULL);
+	page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
+				 NULL);
 	if (!IS_ERR(page)) {
 		wait_on_page_locked(page);
 		if (!PageUptodate(page))