On 3/10/20 5:57 AM, Kashyap Chamarthy wrote:
On Mon, Mar 09, 2020 at 10:42:25AM -0500, Eric Blake wrote:
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+qemu-img backing file without format (since 5.0.0) +'''''''''''''''''''''''''''''''''''''''''''''''''' + +The use of ``qemu-img create``, ``qemu-img rebase``, ``qemu-img +convert``, or ``qemu-img amend`` to create or modify an image that +depends on a backing file now recommends that an explicit backing +format be provided.
Also for the `qemu-img amend` case, I'm not clear if the following scenario ought to throw the warning:
$> ~/build/qemu/qemu-img info --backing-chain overlay1.qcow2 image: overlay1.qcow2 file format: qcow2 virtual size: 4 GiB (4294967296 bytes) disk size: 196 KiB cluster_size: 65536 backing file: base.raw Format specific information: compat: 1.1 lazy refcounts: false refcount bits: 16 corrupt: false
image: base.raw file format: raw virtual size: 4 GiB (4294967296 bytes) disk size: 778 MiB
$> ~/build/qemu/qemu-img amend -o compat=v3 overlay1.qcow2
This particular amend is not changing the backing file, and since I did not add warnings on the opening of an existing unsafe image, it is silent. Instead, you need to test a case where amend provokes a path that would change the backing file (perhaps as simple as '-o backing_file=./base.raw'), while omitting a format for the new backing file string.
$> echo $? 0
I'm just trying to work out the scenarios where the warnings ought to show up (for all the four cases: create, rebase, convert, amend).
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-- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org