From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NHel2-00053m-38 for qemu-devel@nongnu.org; Mon, 07 Dec 2009 09:40:12 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NHekw-0004uz-D4 for qemu-devel@nongnu.org; Mon, 07 Dec 2009 09:40:10 -0500 Received: from [199.232.76.173] (port=52745 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NHekw-0004uX-6B for qemu-devel@nongnu.org; Mon, 07 Dec 2009 09:40:06 -0500 Received: from lo.gmane.org ([80.91.229.12]:42861) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NHekw-00046x-3T for qemu-devel@nongnu.org; Mon, 07 Dec 2009 09:40:06 -0500 Received: from list by lo.gmane.org with local (Exim 4.50) id 1NHekt-0002ka-Qe for qemu-devel@nongnu.org; Mon, 07 Dec 2009 15:40:03 +0100 Received: from nat-pool-brq-t.redhat.com ([209.132.186.34]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 07 Dec 2009 15:40:03 +0100 Received: from pbonzini by nat-pool-brq-t.redhat.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 07 Dec 2009 15:40:03 +0100 From: Paolo Bonzini Date: Mon, 07 Dec 2009 15:38:50 +0100 Message-ID: References: <20091204165301.GA4167@amd.home.annexia.org> <4B1943A0.7030509@codemonkey.ws> <20091204215517.GA5938@amd.home.annexia.org> <4B198D5B.5080803@codemonkey.ws> <4B1A98D9.7010408@redhat.com> <4B1A9C9F.5040705@codemonkey.ws> <20091207105855.GK23109@amd.home.annexia.org> <4B1D057F.9000708@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: <4B1D057F.9000708@codemonkey.ws> Sender: news Subject: [Qemu-devel] Re: [PATCH] Disk image shared and exclusive locks. List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On 12/07/2009 02:39 PM, Anthony Liguori wrote: > > That's a use-case that needs to be thought through. Maybe commit should > attempt to force the lower level to acquire a write lock first? Yes. This is an argument in favor of a "DWIM" lock option instead of giving shared/exclusive choice to the user: do not say what kind of operation you want to do, and let commit upgrade the lock in the future. If the management tools wants to force shared/exclusive, they can do the locking themselves and tell QEMU to not lock. Paolo