Re: [Qemu-devel] [PATCH] qcow2: fix image corruption after committing qcow2 image into base

[Eric Blake <eblake@redhat.com>]

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On 11/14/2017 07:52 AM, Max Reitz wrote:

>>> Hmm - I wonder if persistent bitmaps are also corrupted in the fast path.
>>
>> I also wonder if there's anything better we can do to make us safer by
>> default, so we default to the slow & safe path, unless we can provide
>> we *only* have the subset of features that are safe for the fast path ?
> 
> I have wondered the same but I can't think of any.  The only thing that
> comes close would be to check for which header extensions there are; but
> at the same time, we could just add a comment to qcow2_read_extensions()
> ("If you add a new feature to qcow2, note that you may want to adjust
> the qcow2_make_empty() fastpath conditions").

Indeed, such a comment may be helpful.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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