ovl_want_write
err = ovl_want_write(old);
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);
int ovl_want_write(struct dentry *dentry);
if (!ovl_want_write(dentry)) {
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);
err = ovl_want_write(dentry);