d_exchange
d_exchange(old_dentry, new_dentry);
d_exchange(old_dentry, new_dentry);
EXPORT_SYMBOL(d_exchange);
d_exchange(old_dentry, new_dentry);
extern void d_exchange(struct dentry *, struct dentry *);
d_exchange(tmp_bool_dir, fsi->bool_dir);
d_exchange(tmp_class_dir, fsi->class_dir);