From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O51xi-0000Wd-IN for qemu-devel@nongnu.org; Thu, 22 Apr 2010 15:21:22 -0400 Received: from [140.186.70.92] (port=54661 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O51xf-0000Uq-Au for qemu-devel@nongnu.org; Thu, 22 Apr 2010 15:21:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O51xd-0004PE-EI for qemu-devel@nongnu.org; Thu, 22 Apr 2010 15:21:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47065) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O51xc-0004OI-QW for qemu-devel@nongnu.org; Thu, 22 Apr 2010 15:21:17 -0400 Date: Thu, 22 Apr 2010 20:21:09 +0100 From: "Richard W.M. Jones" Subject: Re: [Qemu-devel] Locking block devices for concurrent access? Message-ID: <20100422192109.GI5858@amd.home.annexia.org> References: <4BA1323F.6080501@msgid.tls.msk.ru> <4BD0972E.9080709@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4BD0972E.9080709@codemonkey.ws> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Michael Tokarev , qemu-devel On Thu, Apr 22, 2010 at 01:36:30PM -0500, Anthony Liguori wrote: > I think we got to the point where there was general agreement on the > usefulness of lock=read|write but where there was still some contention > was on this whole notion of lock=exclusive|shared. > > I believe Richard Jones was driving the original patch and his use case > was libguestfs which really wants lock=exclusive (sort of). But IMHO, > it's very confusing compared to lock=read|write. >>From the libguestfs point of view, any sort of locking would be preferable to the current situation. If someone wants to run with the patch, I posted several versions and there was a lot of discussion on qemu-devel in Nov/Dec 2009, starting with this message: Subject: [Qemu-devel] [PATCH] Disk image shared and exclusive locks. Message-ID: <20091204165301.GA4167@amd.home.annexia.org> Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw