On Thu, Jul 14, 2016 at 02:27:41PM +0200, Martin Kletzander wrote:
Until now we allowed that to happen, however the only thing we supported was either rewiting the file or truncating it. That however doesn't keep the format of that file, so QCOWs, VDIs and all others just became RAW with arbitrary size.
Yes, wiping wipes the format as well. Nothing wrong with that.
Not to mention any domain using such volume could not start anymore. Instead of dealing with the recreation of every single possible file that we have (and possibly failing due to create_tool capabilities) just forbid it for now.
We even state in our documentation that it has no value for file-backed volumes.
Where? Also note, that depending on the actual volume representation, this call may not really overwrite the physical location of the volume. For instance, files stored journaled, log structured, copy-on-write, versioned, and network file systems are known to be problematic. http://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolWipe This only says that it might not work, not that it's completely useless. I think we have a precedent for supporting marginally useful features by still supporting qcow encryption.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=868771
NACK to breaking functionality in order to resolve a 4-year-old synthetic QE-filed bug. I suggest WONTFIX or NOTABUG. Jan