2883 changing "canmount" property to "on" should not always remount dataset

*** 1446,1460 ****
                  goto error;
          }
  
          /*
           * If the dataset's canmount property is being set to noauto,
           * then we want to prevent unmounting & remounting it.
           */
          do_prefix = !((prop == ZFS_PROP_CANMOUNT) &&
              (zprop_string_to_index(prop, propval, &idx,
!             ZFS_TYPE_DATASET) == 0) && (idx == ZFS_CANMOUNT_NOAUTO));
  
          if (do_prefix && (ret = changelist_prefix(cl)) != 0)
                  goto error;
  
          /*
--- 1446,1462 ----
                  goto error;
          }
  
          /*
           * If the dataset's canmount property is being set to noauto,
+          * or being set to on and the dataset is already mounted,
           * then we want to prevent unmounting & remounting it.
           */
          do_prefix = !((prop == ZFS_PROP_CANMOUNT) &&
              (zprop_string_to_index(prop, propval, &idx,
!             ZFS_TYPE_DATASET) == 0) && (idx == ZFS_CANMOUNT_NOAUTO ||
!             (idx == ZFS_CANMOUNT_ON && zfs_is_mounted(zhp, NULL))));
  
          if (do_prefix && (ret = changelist_prefix(cl)) != 0)
                  goto error;
  
          /*