From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Novotny Subject: Re: [PATCH] Device duplicate check fix Date: Wed, 03 Jun 2009 10:45:08 +0200 Message-ID: <4A263814.2030401@redhat.com> References: <4A0D30F7.6010506@redhat.com> <4A255EC5.3050400@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A255EC5.3050400@eu.citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi, you don't see the need to add this check to xend since the same check is already present in the hotplug scripts? So, is this useless and should I do nothing about that and let it be reverted like Keir wrote he did and do nothing about that? Michal Stefano Stabellini 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 >> * >> >> > > >