+ nd->flags &= ~LOOKUP_RCU;
+ if (unlikely(!legitimize_links(nd)))
+ goto out2;
+ if (unlikely(!legitimize_path(nd, &nd->path, nd->seq)))
+ goto out1;
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq)))
+ goto out;
+ }
+ rcu_read_unlock();
+ BUG_ON(nd->inode != parent->d_inode);
+ return 0;
+
+out2:
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+out1:
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+out:
+ rcu_read_unlock();
+ return -ECHILD;
+}
+
+/**
+ * unlazy_child - try to switch to ref-walk mode.
+ * @nd: nameidata pathwalk data
+ * @dentry: child of nd->path.dentry
+ * @seq: seq number to check dentry against
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
+ * for ref-walk mode. @dentry must be a path found by a do_lookup call on
+ * @nd. Must be called from rcu-walk context.
+ * Nothing should touch nameidata between unlazy_child() failure and
+ * terminate_walk().
+ */
+static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
+{
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+