[Libguestfs] Fwd: [Bug 1277705] virt-sparsify --in-place should not sparsify a snapshot

[Richard W.M. Jones]

On Wed, Nov 04, 2015 at 10:49:43AM +0000, Richard W.M. Jones wrote:
> $ qemu-img commit overlay.qcow2 
> Image committed.
> $ du -sh fedora-22.img overlay.qcow2 
> 6.1G fedora-22.img
> 260K overlay.qcow2
> 
> So really there's no use for virt-sparsify on a snapshot (although you
> could also argue this is a bug or missing feature in qemu-img).

I had a bit of discussion with Kevin Wolf on IRC, and he thinks
'qemu-img commit' ought to discard clusters in the backing file when
committing zero clusters.  IOW the above command should have
sparsified the backing file, and if it doesn't, it may be a qemu bug.

In the light of that, I'll drop my patch for RHBZ#1277705, because
maybe we can make this work.

Rich.

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