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Date: Tue, 9 Jan 2018 14:24:25 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 0/2] qemu-img: Let "info" warn
 and go ahead without -U
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Nir Soffer <nirsof@gmail.com>, qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>, Ala Hino <ahino@redhat.com>

On Mon, 01/08 18:57, Kevin Wolf wrote:
> I'm not sure if going back to the old behaviour for a while now would be
> helpful, you'd just end up with an even more confusing set of qemu
> versions, for example:
> 
>     <= 2.9          - works without a warning
>     2.10 and 2.11   - errors out
>     2.12            - prints a warning, but works
>     >= 2.13         - errors out again

What I had in mind is settle on warning for good. QEMU (including qemu-img) is a
low level tool that can be used in many ways that it isn't supposed to, this one
is not more harmful than others (e.g. "qemu-img snapshot ..." on iscsi:// qcow2
image) we allow siliently.

I know this is debatable but I think the #1 purpose of image locking is to
prevent data corruption; #2 IMO is to reduce confusion and misinformation.
While inconsistent output of "qemu-img info" is misinformation, it not working
as before is actually confusion. Though the current behavior is indeed ideal,
the proposed patch is a bit more pragmatical.

Fam