--- fs/unionfs/union_vnops.c.sav	2011-10-01 18:28:02.000000000 -0400
+++ fs/unionfs/union_vnops.c	2011-10-01 18:28:54.000000000 -0400
@@ -748,7 +748,7 @@ unionfs_access(struct vop_access_args *a
 						return (error);
 				}
 			}
-			accmode &= ~VWRITE;
+			accmode &= ~(VWRITE | VAPPEND);
 			accmode |= VREAD; /* will copy to upper */
 		}
 		error = VOP_ACCESS(lvp, accmode, ap->a_cred, td);