From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JIVuO-0001wN-6L for qemu-devel@nongnu.org; Fri, 25 Jan 2008 16:16:20 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JIVuM-0001vu-Rn for qemu-devel@nongnu.org; Fri, 25 Jan 2008 16:16:19 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JIVuM-0001vo-I0 for qemu-devel@nongnu.org; Fri, 25 Jan 2008 16:16:18 -0500 Received: from ecfrec.frec.bull.fr ([129.183.4.8]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1JIVuM-0000CV-2P for qemu-devel@nongnu.org; Fri, 25 Jan 2008 16:16:18 -0500 Subject: Re: [Qemu-devel] [PATCH][RFC] To mount qemu disk image on the host From: Laurent Vivier In-Reply-To: <479A3E1B.2020500@amd.com> References: <1201264245.4114.42.camel@frecb07144> <4799FDBE.6030502@codemonkey.ws> <1201276153.4114.57.camel@frecb07144> <479A3E1B.2020500@amd.com> Date: Fri, 25 Jan 2008 22:17:10 +0100 Message-Id: <1201295830.4288.5.camel@frecb07144> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andre Przywara Cc: qemu-devel@nongnu.org Le vendredi 25 janvier 2008 =C3=A0 20:52 +0100, Andre Przywara a =C3=A9crit= : > Laurent Vivier wrote: > > Le vendredi 25 janvier 2008 =C3=A0 09:18 -0600, Anthony Liguori a =C3= =A9crit : > >> Laurent Vivier wrote: > >>> Hi, > >>> > >>> this patch allows to mount qemu disk images on the host. > >>> =20 > >=20 > > Sorry, I didn't see you did a similar work 19 months ago. > >> Note, the general problem with this approach is that mounting a NBD=20 > >> device locally with write access can lead to dead locks. If you look=20 > >> through the mailing list archives, you'll find a number of conversatio= ns=20 > >> on the topic. > I sometimes ago was also working on a nbd implementation for=20 > qcow-images, but I came to the same deadlock conclusion. (At least=20 > theoretically, I didn't finish this as I ran first into debugging=20 > problems and secondly out of time). But IMHO this only applies to=20 > localhost mounts, real network mounting should work (this is actually=20 As it seems a problem related to the page cache, perhaps we could open the QCOW file with O_DIRECT to avoid the problem ? Laurent --=20 ----------------- Laurent.Vivier@bull.net ------------------ "La perfection est atteinte non quand il ne reste rien =C3=A0 ajouter mais quand il ne reste rien =C3=A0 enlever." Saint Exup=C3=A9ry