tcmur/unmap: fix the NOTE comment
@@ -1882,8 +1882,11 @@ static int handle_unmap_internal(struct tcmu_device *dev, struct tcmulib_cmd *or
* large num blocks into OPTIMAL UNMAP GRANULARITY size.
*
* NOTE: here we always asumme the OPTIMAL UNMAP GRANULARITY
- * equals to UNMAP GRANULARITY ALIGNMENT, if not in feature
- * and following align and split algorithm should be changed.
+ * equals to UNMAP GRANULARITY ALIGNMENT to simplify the
+ * calculate algorithm, but in future for some new devices
+ * who could support and they must have different values
+ * to make the unmap to be more efficient, the following
+ * align and split calculate algorithm should be changed.
*/
lbas = opt_unmap_gran - (lba & mask);
lbas = min(lbas, nlbas);
