[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH v3 4/4] qemu-img: Deprecate use of -b without -F

From: Eric Blake
Subject: Re: [PATCH v3 4/4] qemu-img: Deprecate use of -b without -F
Date: Tue, 10 Mar 2020 07:17:15 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0

On 3/10/20 5:57 AM, Kashyap Chamarthy wrote:
On Mon, Mar 09, 2020 at 10:42:25AM -0500, Eric Blake wrote:


+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 $?

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).


Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

reply via email to

[Prev in Thread] Current Thread [Next in Thread]