[PATCH] invalidate_inodes2(): mark pages not uptodate

Andrea Arcangeli <andrea@suse.de> points out that invalidate_inode_pages2() is
supposed to mark mapped-into-pagetable pages as not uptodate so that next time
someone faults the page in we will go get a new version from backing store.

The callers are the direct-io code and the NFS "something changed on the
server" code.  In both these cases we do need to go and re-read the page.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/truncate.c

@@ -243,6 +243,10 @@ EXPORT_SYMBOL(invalidate_inode_pages);
  * where the page is seen to be mapped into process pagetables.  In that case,
  * the page is marked clean but is left attached to its address_space.
  *
+ * The page is also marked not uptodate so that a subsequent pagefault will
+ * perform I/O to bringthe page's contents back into sync with its backing
+ * store.
+ *
  * FIXME: invalidate_inode_pages2() is probably trivially livelockable.
  */
 void invalidate_inode_pages2(struct address_space *mapping)
@@ -260,10 +264,12 @@ void invalidate_inode_pages2(struct address_space *mapping)
 			if (page->mapping == mapping) {	/* truncate race? */
 				wait_on_page_writeback(page);
 				next = page->index + 1;
-				if (page_mapped(page))
+				if (page_mapped(page)) {
 					clear_page_dirty(page);
-				else
+					ClearPageUptodate(page);
+				} else {
 					invalidate_complete_page(mapping, page);
+				}
 			}
 			unlock_page(page);
 		}