[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/ntfs/attrib.c b/fs/ntfs/attrib.c
index 1663f5c..6708e1d 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -2529,8 +2529,7 @@
 	end >>= PAGE_CACHE_SHIFT;
 	/* If there is a first partial page, need to do it the slow way. */
 	if (start_ofs) {
-		page = read_cache_page(mapping, idx,
-				(filler_t*)mapping->a_ops->readpage, NULL);
+		page = read_mapping_page(mapping, idx, NULL);
 		if (IS_ERR(page)) {
 			ntfs_error(vol->sb, "Failed to read first partial "
 					"page (sync error, index 0x%lx).", idx);
@@ -2600,8 +2599,7 @@
 	}
 	/* If there is a last partial page, need to do it the slow way. */
 	if (end_ofs) {
-		page = read_cache_page(mapping, idx,
-				(filler_t*)mapping->a_ops->readpage, NULL);
+		page = read_mapping_page(mapping, idx, NULL);
 		if (IS_ERR(page)) {
 			ntfs_error(vol->sb, "Failed to read last partial page "
 					"(sync error, index 0x%lx).", idx);