Takes an operation, an optional requested bandwidth
limit override, and a list of storages involved in the
operation and lowers the requested bandwidth against global
and storage-specific limits unless the user has permissions
to change those.
This means:
* Global limits apply to all users without Sys.Modify on /
(as they can change datacenter.cfg options via the API).
* Storage specific limits apply to users without
Datastore.Allocate access on /storage/X for any involved
storage X.
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
