Bug 1428404

Description of problem:

This bug is a follow up to bz:
https://bugzilla.redhat.com/show_bug.cgi?id=1415759

hen trying to sparsify a direct lun via the REST API the detail of the failure is incorrect, I get:

<action>
<async>false</async>
<fault>
<detail>[User is not authorized to perform this action.]</detail>
<reason>Operation Failed</reason>
</fault>
<grace_period>
<expiry>10</expiry>
</grace_period>
<status>failed</status>
</action>

This is although I'm running the cmd as admin with superUser permissions on the vm, just the same as other vms with which the sparsify action works or fails with specific msg, e.g.

[Cannot sparsify Virtual Disk. Sparsifying is not supported for preallocated disk bla_Disk1.]

Please check it out.

Version-Release number of selected component (if applicable):
4.1.1.2-0.1.el7

How reproducible:
always

Steps to Reproduce:
1. Have a direct lun.
2. Try to sparsify it via the REST API:
POST http://<host_name>:8080/ovirt-engine/api/disks/<direct_lun_id>/sparsify

Actual results:
<action>
<async>false</async>
<fault>
<detail>[User is not authorized to perform this action.]</detail>
<reason>Operation Failed</reason>
</fault>
<grace_period>
<expiry>10</expiry>
</grace_period>
<status>failed</status>
</action>

Expected results:
Should be passed to the backend and let it return an error message that direct luns can't be sparsified.