diff -Nurp linux-2.6.17.7-vs2.1.1-rc28/fs/namei.c linux-2.6.17.7-vs2.1.1-rc28.cow/fs/namei.c
--- linux-2.6.17.7-vs2.1.1-rc28/fs/namei.c	2006-08-14 20:50:48.000000000 +0200
+++ linux-2.6.17.7-vs2.1.1-rc28.cow/fs/namei.c	2006-08-16 20:48:40.000000000 +0200
@@ -264,7 +264,7 @@ int permission(struct inode *inode, int 
 		/*
 		 * Nobody gets write access to an immutable file.
 		 */
-		if (IS_IMMUTABLE(inode))
+		if (IS_IMMUTABLE(inode) && !IS_COW(inode))
 			return -EACCES;
 	}