+ * directories on the FAT filesystem.
+ *
+ * Since we don't follow mount points on Windows, we don't need to query
+ * the volume ID per-file. Just once, for the root, is enough. But we
+ * can't simply pass 0, because then there could be inode collisions
+ * among multiple calls to win32_build_dentry_tree() that are scanning
+ * files on different volumes. */