[PATCH] symlink: fix missing 'depth' initialization

Now we always care about one part of nameidata --- ->depth.  And we need
to make sure it's always initialized.

generic_readlink() was missing that part.

fs/namei.c

@@ -2197,7 +2197,9 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const c
 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 {
 	struct nameidata nd;
-	int res = dentry->d_inode->i_op->follow_link(dentry, &nd);
+	int res;
+	nd.depth = 0;
+	res = dentry->d_inode->i_op->follow_link(dentry, &nd);
 	if (!res) {
 		res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
 		if (dentry->d_inode->i_op->put_link)