Re: [libvirt] [PATCH 0/2] Alter refresh algorithm for volWipe

On Fri, Aug 25, 2017 at 07:52:25AM -0400, John Ferlan wrote: > > > On 08/25/2017 05:44 AM, Martin Kletzander wrote: >> On Thu, Aug 24, 2017 at 06:28:27PM -0400, John Ferlan wrote: >>> Alter wipeVol to do same refresh operation as pool refresh would do. >>> >> >> I think we should rather keep the format as it is. Did I miss something >> here or isn't the source of the problem just the fact that we wipe the >> volume without keeping the format? >> > > Once you "wipe" the file/image the format that was there (such as qcow2 > as noted in the bz from patch2) is no longer there. > > Consider the following sequence: > > virsh vol-create-as default bz 10M --format qcow2 > > virsh vol-dumpxml bz default | grep format > <format type='qcow2'/> > > qemu-img info /home/vm-images/bz > image: /home/vm-images/bz > file format: qcow2 > virtual size: 10M (10485760 bytes) > disk size: 196K > cluster_size: 65536 > Format specific information: > compat: 0.10 > refcount bits: 16 > > virsh vol-wipe bz default > > qemu-img info /home/vm-images/bz > image: /home/vm-images/bz > file format: raw > virtual size: 196K (200704 bytes) > disk size: 196K > > virsh vol-dumpxml bz default | grep format > <format type='qcow2'/> > > (without the patch in 2/2 of course) > > BTW: I did consider just changing the format to RAW regardless, but > figured that was just too simple and may not be the right answer for > every case. > Sure, but that's not my point. My point is that instead of rewriting the data with zeros, we could re-initialize it. Anyway, from what I see in the docs, we "fixed" it by documenting this behaviour already, so my point is moo: https://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolWipe

(I guess I should know that when I pushed that documentation into the tree) So ACK series.