From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Stabellini Subject: Re: [PATCH] Device duplicate check fix Date: Tue, 2 Jun 2009 18:17:57 +0100 Message-ID: <4A255EC5.3050400@eu.citrix.com> References: <4A0D30F7.6010506@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A0D30F7.6010506@redhat.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: Michal Novotny Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org 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 > * >