return -EINVAL;
return -EIO;
fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count){	struct bin_attribute * attr = to_bin_attr(dentry);	struct kobject * kobj = to_kobj(dentry->d_parent);	if (!attr->read)		return -EINVAL;	return attr->read(kobj, buffer, off, count);}