On Fri, Nov 14, 2025 at 02:33:20AM -0500, zrm wrote:
> Here's the other one:
>
> # virsh qemu-monitor-command trogdor --pretty
> '{"execute":"query-block"}'|grep detect_zeroes
> "detect_zeroes": "unmap",
>
> # virsh snapshot-create-as --domain trogdor snap42 --diskspec
> vda,file=/var/lib/libvirt/images/trogdor-snap42.qcow2 --disk-only
>
> Domain snapshot snap42 created
>
> # virsh qemu-monitor-command trogdor --pretty
> '{"execute":"query-block"}'|grep detect_zeroes
> "detect_zeroes": "off",
>
> This one isn't an issue for snapshot deletion or blockcommit. But if you
> actually wanted detect_zeroes='unmap' in the active top image, creating a
> snapshot turns it off until you shut down the VM because
> qemuDomainPrepareDiskSourceData() isn't properly copying the detect_zeroes
> property to the new top image during snapshot creation. In theory qemu could
> also deduce that one without being told if it gets a new top image when
> detect_zeroes was enabled for the previous one, but it isn't doing that even
> in sid and even if it was that would still leave the "detect_zeroes" field
> in "struct _virStorageSource" set to the wrong value for the new top image
> in libvirt.
>
> I suppose that one wants to be a separate bug at this point, doesn't it?This is currently being looked at. I'll keep you posted. -- Andrea Bolognani <[email protected]> Resistance is futile, you will be garbage collected.
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