From: Kevin Wolf <kwolf@redhat.com>
To: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com,
levinsasha928@gmail.com, penberg@kernel.org, kwolf@redhat.com,
tglx@linutronix.de
Cc: linux-tip-commits@vger.kernel.org, kvm-devel <kvm@vger.kernel.org>
Subject: Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption
Date: Thu, 21 Jul 2011 10:09:13 +0200 [thread overview]
Message-ID: <4E27DEA9.20404@redhat.com> (raw)
In-Reply-To: <tip-4839bcd6b04a1b628f0f00d535ddca2ee872e9fa@git.kernel.org>
Am 20.07.2011 21:49, schrieb tip-bot for Pekka Enberg:
> Commit-ID: 4839bcd6b04a1b628f0f00d535ddca2ee872e9fa
> Gitweb: http://git.kernel.org/tip/4839bcd6b04a1b628f0f00d535ddca2ee872e9fa
> Author: Pekka Enberg <penberg@kernel.org>
> AuthorDate: Wed, 20 Jul 2011 16:28:31 +0300
> Committer: Pekka Enberg <penberg@kernel.org>
> CommitDate: Wed, 20 Jul 2011 16:28:31 +0300
>
> kvm tools, qcow: Fix copy-on-write image corruption
>
> We don't handle refcount table properly so make sure we only write to clusters
> that have the "copied" flag set.
>
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Sasha Levin <levinsasha928@gmail.com>
> Signed-off-by: Pekka Enberg <penberg@kernel.org>
Hm, I must have missed this patch on the KVM mailing list...
You should also error out before creating a new L2 table as its refcount
would have to be updated, too. On the other hand, the patch is a bit too
restrictive, because it applies the check to qcow1 which doesn't even
have a refcount table.
I'm not sure if everyone is aware of it, so another hint: Now that you
can't grow qcow2 any more, you might find it useful to use qemu-img
create -f qcow2 -o preallocation=metadata, so that all clusters are
already present and you don't get random failures.
Kevin
next parent reply other threads:[~2011-07-21 8:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-4839bcd6b04a1b628f0f00d535ddca2ee872e9fa@git.kernel.org>
2011-07-21 8:09 ` Kevin Wolf [this message]
2011-07-22 8:21 ` [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption Pekka Enberg
2011-07-22 8:33 ` Kevin Wolf
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