From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36738) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhJat-0001Po-0M for qemu-devel@nongnu.org; Tue, 06 Sep 2016 12:51:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bhJao-0007lY-LT for qemu-devel@nongnu.org; Tue, 06 Sep 2016 12:51:30 -0400 Date: Tue, 6 Sep 2016 17:51:15 +0100 From: "Daniel P. Berrange" Message-ID: <20160906165115.GO10095@redhat.com> Reply-To: "Daniel P. Berrange" References: <1464943756-14143-1-git-send-email-famz@redhat.com> <1464943756-14143-4-git-send-email-famz@redhat.com> <20160617092308.GC5431@noname.redhat.com> <20160705133726.GC5882@noname.redhat.com> <20160708025642.GB13961@ad.usersys.redhat.com> <20160708095019.GF14684@noname.redhat.com> <20160906164555.GI4667@noname.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160906164555.GI4667@noname.redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v6 03/22] blockdev: Add and parse "lock-mode" option for image locking List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: Max Reitz , Fam Zheng , qemu-block@nongnu.org, rjones@redhat.com, Markus Armbruster , qemu-devel@nongnu.org, stefanha@redhat.com, den@openvz.org, pbonzini@redhat.com, jcody@redhat.com On Tue, Sep 06, 2016 at 06:45:55PM +0200, Kevin Wolf wrote: > Am 08.07.2016 um 15:05 hat Max Reitz geschrieben: > > I think whether to lock a BDS chain is a host-side property and has not > > a lot to do with the guest, thus it should be a BDS property. I can > > imagine that a guest may say that sharing should be disallowed under all > > circumstances, but a guest is never able to decide to allow sharing. > > Well, yes and no. The decision which lock mode to use is at the node > level, no doubt. But it's not something that a user can configure. > Non-raw images simply can't be shared and the user can't do anything > about it. Why should they have an option to specify a lock mode when > there is only one correct setting? I'm not sure that's true for all non-raw images. I understand things like qcow2 won't work, because of cached metadata which can be updated by QEMU during writes, but I think the luks format ought to be safe as the cached metadata is never changed. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|