From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=52298 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Pke6E-0002jV-6e for qemu-devel@nongnu.org; Wed, 02 Feb 2011 09:54:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PkXal-0005Ri-Dw for qemu-devel@nongnu.org; Wed, 02 Feb 2011 02:57:32 -0500 Received: from mail-yi0-f45.google.com ([209.85.218.45]:55819) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PkXal-0005Rd-BX for qemu-devel@nongnu.org; Wed, 02 Feb 2011 02:57:31 -0500 Received: by yie21 with SMTP id 21so3181571yie.4 for ; Tue, 01 Feb 2011 23:57:30 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1296557928-30019-2-git-send-email-Jes.Sorensen@redhat.com> References: <1296557928-30019-1-git-send-email-Jes.Sorensen@redhat.com> <1296557928-30019-2-git-send-email-Jes.Sorensen@redhat.com> Date: Wed, 2 Feb 2011 07:57:30 +0000 Message-ID: Subject: Re: [Qemu-devel] [PATCH 1/2] Add virtagent file system freeze/thaw 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: Jes.Sorensen@redhat.com Cc: agl@us.ibm.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com On Tue, Feb 1, 2011 at 10:58 AM, wrote: > From: Jes Sorensen > > Implement freeze/thaw support in the guest, allowing the host to > request the guest freezes all it's file systems before a live snapshot > is performed. > =A0- fsfreeze(): Walk the list of mounted local real file systems, > =A0 =A0 =A0 =A0 =A0 =A0 =A0 and freeze them. Does this add a requirement that guest agent code issues no disk I/O in its main loop (e.g. logging)? Otherwise we might deadlock ourselves waiting for I/O which is never issued. Stefan