namei: we never need more than MAXSYMLINKS entries in nd->stack

The only reason why we needed one more was that purely nested
MAXSYMLINKS symlinks could lead to path_init() using that many
entries in addition to nd->stack[0] which it left unused.

That can't happen now - path_init() starts with entry 0 (and
trailing_symlink() is called only when we'd already encountered
one symlink, so no more than MAXSYMLINKS-1 are left).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -528,7 +528,7 @@ static void restore_nameidata(struct nameidata *nd)
 
 static int __nd_alloc_stack(struct nameidata *nd)
 {
-	struct saved *p = kmalloc((MAXSYMLINKS + 1) * sizeof(struct saved),
+	struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
 				  GFP_KERNEL);
 	if (unlikely(!p))
 		return -ENOMEM;