From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=42739 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OuTKI-0000m9-Td for qemu-devel@nongnu.org; Sat, 11 Sep 2010 12:53:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OuTKH-00005v-L6 for qemu-devel@nongnu.org; Sat, 11 Sep 2010 12:53:18 -0400 Received: from mail-vw0-f45.google.com ([209.85.212.45]:49264) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OuTKH-00005n-IK for qemu-devel@nongnu.org; Sat, 11 Sep 2010 12:53:17 -0400 Received: by vws19 with SMTP id 19so3746445vws.4 for ; Sat, 11 Sep 2010 09:53:16 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1284213896-12705-3-git-send-email-aliguori@us.ibm.com> References: <1284213896-12705-1-git-send-email-aliguori@us.ibm.com> <1284213896-12705-3-git-send-email-aliguori@us.ibm.com> Date: Sat, 11 Sep 2010 17:53:16 +0100 Message-ID: Subject: Re: [Qemu-devel] [PATCH 2/3] block-nbd: fix use of protocols in backing files and nbd probing From: Stefan Hajnoczi Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Kevin Wolf , Juan Quintela , qemu-devel@nongnu.org, Stefan Hajnoczi On Sat, Sep 11, 2010 at 3:04 PM, Anthony Liguori wrot= e: > Additionally, there's a spurious read when using an nbd protocol that can= be > quite destructive when using copy-on-read. =A0Potentially, this can lead = to > probing an image file over top of NBD but this is completely wrong as NBD > devices are not growable. Can you describe the copy-on-read scenario where the 2 KB probe read is a problem? Accessing a fixed size image file over NBD is probably uncommon, but I'm not sure if there's a reason to forbid it. Stefan