Improve update volume validation with user storage disks

[dlangenk]

There were two occasions where users could not trigger the reprocessing of images

• In one case the user was not owning the storage disk so the reprocessing was forbidden although the user had access to the volume (but a warning was shown)
• In the other case the reprocessing just didn't happen although the user should have been able to trigger it (without any warning or anything, this time)

[mzur]

The reprocessing is only triggered if the request comes from a global admin.

In the other case you say that the user wanted to update the name of the volume but wasn't allowed because they don't own the storage disk? I guess we could allow this as long as the volume URL is not updated.

[dlangenk]

I thought that project admins could also trigger this, at least by changing the url and adding a "/".

In the other case the user was admin of a project with cloned volumes. The storage disk did likely not belong to the user. I though the she could trigger the reprocessing by hitting save, but she got an error message instead.

[mzur]

No, adding a "/" should not trigger the reprocessing as a regular user. I'd rather stick to this as the reprocessing is expensive.

I'll change this issue to be about enabling project admins that are not owners of the storage disk to update the volume as long as they do not change the URL (unless they replace it with their own storage disk). So:

Change the update volume validation to allow updates of users that don't own the storage disk in the volume URL as long as the URL is not changed in the update request.