vxflex driver not handle round_volume_capacity correctly

[zhimou.peng]

when create a volume from image, the volume size is not handle by round_volume_capacity correctly.

root@scaleioubuntu:/openstack# openstack volume create --image cirros-0.3.5-x86_64-disk --size 1 zhpeng4
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| consistencygroup_id | None |
| created_at | 2020-05-07T08:08:19.000000 |
| description | None |
| encrypted | False |
| id | 7679faf3-096a-40a5-a7f2-1c5b8bcab8a9 |
| migration_status | None |
| multiattach | False |
| name | zhpeng4 |
| properties | |
| replication_status | None |
| size | 1 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| type | scaleio1 |
| updated_at | None |
| user_id | 2dbfd0934e3b4d70a275c86a0e58c811 |
+---------------------+--------------------------------------+
root@scaleioubuntu:/opt/stack/new/devstack# openstack volume create --size 1 zhpeng5
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| consistencygroup_id | None |
| created_at | 2020-05-07T08:26:47.000000 |
| description | None |
| encrypted | False |
| id | 9a14b837-1c17-4b4b-a92d-bd6d4ce1f923 |
| migration_status | None |
| multiattach | False |
| name | zhpeng5 |
| properties | |
| replication_status | None |
| size | 1 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| type | scaleio1 |
| updated_at | None |
| user_id | 2dbfd0934e3b4d70a275c86a0e58c811 |
+---------------------+--------------------------------------+

root@scaleioubuntu:/openstack# openstack volume list
+--------------------------------------+---------+-----------+------+-------------+
| ID | Name | Status | Size | Attached to |
+--------------------------------------+---------+-----------+------+-------------+
| 9a14b837-1c17-4b4b-a92d-bd6d4ce1f923 | zhpeng5 | available | 8 | |
| 7679faf3-096a-40a5-a7f2-1c5b8bcab8a9 | zhpeng4 | available | 1 | |
+--------------------------------------+---------+-----------+------+-------------+

[Ivan Pchelintsev (pcheli)]

It is a known issue.
Volumes on VxFlex OS side are created with the correct size but in OpenStack the size is the one that the user selected.
As I can see we have 3 options:
1) don't make any changes but describe this behaviour in docs
2) prohibit to create volumes from a snapshot/volume if its size is not granular of 8
3) extend the newly created volume size in OpenStack

For options 2 and 3 we will get at least two tempest tests failed.