Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption

2011-07-22 Thread 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.


Pekka
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Re: [tip:tools/kvm] kvm tools, qcow: Fix copy-on-write image corruption

2011-07-22 Thread Kevin Wolf
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
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