feature-3060: enable disk discard option for qemu-kvm

[atodorov-storpool]

This is proposed solution for feature in Backlog #3060 (http://dev.opennebula.org/issues/3060)

By default this feature is not touching the xml configuration for backward compatibility.

There is global VM config in vmm/remotes/kvm/kvmrc named DEFAULT_ATTACH_DISCARD that if set will enforce the discard option to all VMs if there is no configuranito per template.

It is possible to enable the discard feature per VM in their template by adding
DISCARD=unmap
to enable and
DISCARD=ignore
to disable the discard

[rsmontero]

Now in master thanks

[atodorov-storpool]

a patch slipped out bug in the discard= construction - there is an extra single comma (') slipped out that I fixed on the buld host but obviously forgot to update the git source tree.
in the patch for src/vmm/LibVirtDriverKVM.cc:
file << "' discard='";
should be:
file << " discard='";

What is the proper way? add the patch and generate the pull request again?

[rsmontero]

I'll fix it

[rsmontero]

Here, can you check it?

commit 997eaa0
Author: Ruben S. Montero rsmontero@opennebula.org
Date: Wed Jul 8 11:24:58 2015 +0200

feature #3060: Fix wrong format of discard. Thanks to Anton Todorov

[atodorov-storpool]

Yes, this way the cache option is OK without second quotation (') at the end of the parameter.