when users try to create a backup from a snapshot, the volume
related to the snapshot is set to backing-up during the action
and can't be used for other actions.
When create a backup from a large snapshot, such as larger
than 1 TB, it will cost few hours generally. It's really a
problem that the volume is not available for such a long time.
If the snapshot is provided, we change the status of the snapshot;
otherwise, we change the status of the volume as usual.
This patch added "backing-up" status for snapshot as well
DocImpact
Change-Id: I86d34c470fabbf4132b5e004d9f368e751c893a5
Closes-bug: #1670541
d304f621c2