From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:54929) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S22YS-00005m-Oo for qemu-devel@nongnu.org; Mon, 27 Feb 2012 10:32:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S22YM-0000bV-TL for qemu-devel@nongnu.org; Mon, 27 Feb 2012 10:32:00 -0500 Received: from mail-lpp01m010-f45.google.com ([209.85.215.45]:35127) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S22YM-0000aN-Ls for qemu-devel@nongnu.org; Mon, 27 Feb 2012 10:31:54 -0500 Received: by lahe6 with SMTP id e6so413420lah.4 for ; Mon, 27 Feb 2012 07:31:53 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <4F4B9FE5.4000807@redhat.com> References: <4F4B9280.20807@redhat.com> <4F4B9FE5.4000807@redhat.com> Date: Mon, 27 Feb 2012 15:31:53 +0000 Message-ID: From: Stefan Hajnoczi Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2 1/2] qapi: Introduce blockdev-group-snapshot-sync command List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: jcody@redhat.com Cc: kwolf@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, lcapitulino@redhat.com, pbonzini@redhat.com, eblake@redhat.com On Mon, Feb 27, 2012 at 3:23 PM, Jeff Cody wrote: > On 02/27/2012 09:40 AM, Stefan Hajnoczi wrote: >> On Mon, Feb 27, 2012 at 2:26 PM, Jeff Cody wrote: >>> On 02/27/2012 06:13 AM, Stefan Hajnoczi wrote: >>>> On Sun, Feb 26, 2012 at 7:31 PM, Jeff Cody wrote: >>>>> + * It is assumed that bs_new already points to an existing image, >>>>> + * with the correct backing filename of top->backing_file >>>> >>>> Not sure what this means. =A0Isn't bs_new going to use bs_top as its >>>> backing file? =A0Why "top->backing_file"? >>> >>> Sorry, that should have been 'bs_top->backing_file'. The image file is >>> not created by this function. =A0I added some more explanation, and >>> corrected that typo, in the above comment block. =A0Let me know if you >>> think it still needs more clarification. >> >> I still don't follow. =A0Old bs_top's image file itself becomes the >> backing file, not bs_top->backing_file. =A0Perhaps I'm misinterpreting >> because of how swap changes bs_top and bs_new, but I'm reading it from >> the perspective of the caller when they pass in bs_top. >> > > Maybe it would be better to just replace that part of the comment with > something that says "This function does not create the image file". > > The function bdrv_append() will neither create the image file, or set > (in the case of qcow2) the extended headers of the file to have the > backing filename. =A0It is only concerned with the bs contents. Makes sense. Stefan