* Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption [not found] <tip-4839bcd6b04a1b628f0f00d535ddca2ee872e9fa@git.kernel.org> @ 2011-07-21 8:09 ` Kevin Wolf 2011-07-22 8:21 ` Pekka Enberg 0 siblings, 1 reply; 3+ messages in thread From: Kevin Wolf @ 2011-07-21 8:09 UTC (permalink / raw) To: linux-kernel, mingo, hpa, levinsasha928, penberg, kwolf, tglx Cc: linux-tip-commits, kvm-devel 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 ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption 2011-07-21 8:09 ` [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption Kevin Wolf @ 2011-07-22 8:21 ` Pekka Enberg 2011-07-22 8:33 ` Kevin Wolf 0 siblings, 1 reply; 3+ messages in thread From: Pekka Enberg @ 2011-07-22 8:21 UTC (permalink / raw) To: Kevin Wolf Cc: linux-kernel, mingo, hpa, levinsasha928, tglx, linux-tip-commits, kvm-devel On Thu, 21 Jul 2011, Kevin Wolf wrote: > Hm, I must have missed this patch on the KVM mailing list... It wasn't on the list, sorry. > 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. Oh, right, I broken QCOW1. > 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. Yup, I'm aware that you can't grow images anymore. The patch was meant as a stop-gap measure while I'm hacking on refcount table support. Pekka ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption 2011-07-22 8:21 ` Pekka Enberg @ 2011-07-22 8:33 ` Kevin Wolf 0 siblings, 0 replies; 3+ messages in thread From: Kevin Wolf @ 2011-07-22 8:33 UTC (permalink / raw) To: Pekka Enberg Cc: linux-kernel, mingo, hpa, levinsasha928, tglx, linux-tip-commits, kvm-devel Am 22.07.2011 10:21, schrieb Pekka Enberg: > On Thu, 21 Jul 2011, Kevin Wolf wrote: >> Hm, I must have missed this patch on the KVM mailing list... > > It wasn't on the list, sorry. > >> 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. > > Oh, right, I broken QCOW1. > >> 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. > > Yup, I'm aware that you can't grow images anymore. The patch was meant as > a stop-gap measure while I'm hacking on refcount table support. Yeah, I was pretty sure you were aware of _that_, but maybe not everyone knows that metadata preallocation exists. Kevin ^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-07-21 8:09 ` [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption Kevin Wolf
2011-07-22 8:21 ` Pekka Enberg
2011-07-22 8:33 ` Kevin Wolf
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