Re: [Xen-devel] [PATCH] Device duplicate check fix

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

It's already reverted, since it broke automated localhost migration tests.

 -- Keir

On 02/06/2009 18:17, "Stefano Stabellini" <stefano.stabellini@xxxxxxxxxxxxx>
wrote:

> Sorry for the late reply, but I only now I realized that this patch
> breaks stubdoms: an exception is needed to allow a disk to be shared
> between the guest and its own stubdom.
> 
> Beside I do not see the need to add this check to xend since the same
> check is already present in the hotplug scripts.
> 
> Michal Novotny wrote:
> 
>> *Hello,
>> I've checked the duplicate-check code here and I found that's checked
>> only in the context of one domain but not cross-domain. The thing is
>> that we should check tap/vbd device cross-domain not to allow another
>> guest to use the same disk image in some circumstances to prevent VM's
>> disk corruption.
>> 
>> The patch included denies disk image addition under those circumstances:
>>  1. **We're adding read-only disk that's already used as write-exclusive
>>  2. **We're adding write-shared disk that's already used as write-exclusive
>>  3. **We're adding write-exclusive disk that's already used
>>  4. **We're adding read-only disk that's already used as write-shared*
>> (because of I/O caching issues etc.)
>> *
>> The vif device duplicate check remains the same it was and it's checked
>> in the context of current domain only so that behaviour has been preserved.
>> 
>> Michal
>> 
>> Signed-off-by: Michal Novotny <minovotn@xxxxxxxxxx>
>> *
>> 
> 
> 
> 
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