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From: Max Reitz <mreitz@redhat.com>
To: Eric Blake <eblake@redhat.com>,
	lampahome <pahome.chen@mirlab.org>,
	QEMU Developers <qemu-devel@nongnu.org>,
	Qemu-block <qemu-block@nongnu.org>,
	Markus Armbruster <armbru@redhat.com>
Subject: Re: [Qemu-devel] Can I only commit from active image to corresponding range of its backing file by qemu cmd?
Date: Thu, 13 Sep 2018 21:41:05 +0200	[thread overview]
Message-ID: <81bba910-3e33-376d-f490-151fcccd4322@redhat.com> (raw)
In-Reply-To: <56133002-7a79-bf6a-8835-fba043638224@redhat.com>

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On 13.09.18 20:37, Max Reitz wrote:

[...]

> Or, we would have to use backing=null, but for some reason that doesn't
> work.  I'll have to investigate.

Turns out this was fixed in e59a0cf17b1b9932b65e6fc25d6856976f5e4831.

(Why does Fedora still have only qemu 2.11?)

> So rebase will need to do:
> 
> $ qemu-img rebase -u -b '' img.003
> 
> $ qemu-img convert -O qcow2 \
>     "json:{'driver':'raw','offset':0,'size':1048576,\
>            'file':{'driver':'qcow2',\
>                    'file':{'driver':'file','filename':'img.003'}}}" \
>     "json:{'driver':'null-co','size':2097152}" \
>     img.003.commit.000
> 
> $ qemu-img convert -O qcow2 \
>     "json:{'driver':'null-co','size':1048576}" \
>     "json:{'driver':'raw','offset':1048576,'size':2097152,\
>            'file':{'driver':'qcow2',\
>                    'file':{'driver':'file','filename':'img.003'}}}" \
>     img.003.nocommit

So starting with 2.12, putting a "'backing':null" behind
"'driver':'qcow2," will work just as well as rebasing img.003.

Max


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  reply	other threads:[~2018-09-13 19:41 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-13  3:33 [Qemu-devel] Can I only commit from active image to corresponding range of its backing file by qemu cmd? lampahome
2018-09-13 13:22 ` Max Reitz
2018-09-13 17:05   ` Eric Blake
2018-09-13 18:37     ` Max Reitz
2018-09-13 19:41       ` Max Reitz [this message]
2018-09-13 20:06         ` Eric Blake
2018-09-13 20:01       ` Eric Blake
2018-09-13 20:44         ` Max Reitz
2018-09-14  2:19           ` lampahome
2018-09-14 14:48             ` Eric Blake

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