From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39623) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xhhdw-00017r-BQ for qemu-devel@nongnu.org; Fri, 24 Oct 2014 12:23:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xhhdr-0006Yi-DQ for qemu-devel@nongnu.org; Fri, 24 Oct 2014 12:23:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6325) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xhhdr-0006YX-5d for qemu-devel@nongnu.org; Fri, 24 Oct 2014 12:23:07 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s9OGN6rs003339 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Fri, 24 Oct 2014 12:23:06 -0400 Message-ID: <544A7CE9.4090905@redhat.com> Date: Fri, 24 Oct 2014 10:23:05 -0600 From: Eric Blake MIME-Version: 1.0 References: <1414159063-25977-1-git-send-email-mreitz@redhat.com> <1414159063-25977-12-git-send-email-mreitz@redhat.com> In-Reply-To: <1414159063-25977-12-git-send-email-mreitz@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FKmJ6Emd4GejmsmNnAmIJAUePpPnvqg91" Subject: Re: [Qemu-devel] [PATCH v14 11/14] qemu-img: Specify backing file for commit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz , qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --FKmJ6Emd4GejmsmNnAmIJAUePpPnvqg91 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 10/24/2014 07:57 AM, Max Reitz wrote: > Introduce a new parameter for qemu-img commit which may be used to > explicitly specify the backing file into which an image should be > committed if the backing chain has more than a single layer. >=20 > Signed-off-by: Max Reitz > --- > qemu-img-cmds.hx | 4 ++-- > qemu-img.c | 32 +++++++++++++++++++++++--------- > qemu-img.texi | 12 +++++++++++- > 3 files changed, 36 insertions(+), 12 deletions(-) >=20 > +If the backing chain of the given image file @var{filename} has more t= han one > +layer, the backing file into which the changes will be committed may b= e > +specified as @var{base} (which has to be part of @var{filename}'s back= ing > +chain). If @var{base} is not specified, the immediate backing file of = the top > +image (which is @var{filename}) will be used. For reasons of consisten= cy, > +explicitly specifying @var{base} will always imply @code{-d} (otherwis= e, an > +image could be committed in an indirect backing file and emptying it m= ight lead > +to different data being read from it because the intermediate backing = chain > +overrules the commit target). I wonder if there is any better wording to make it obvious that both instances of 'it' in the (comment) refer to the further reference of the top image, and not the closer reference to the indirect backing file. May= be: =2E..always imply -d (since emptying an image after committing to an indirect backing file would lead to different data being read from the image due to content in the intermediate backing chain overruling the commit target) But I can live with the wording as you proposed it, so: Reviewed-by: Eric Blake --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --FKmJ6Emd4GejmsmNnAmIJAUePpPnvqg91 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg iQEcBAEBCAAGBQJUSnzpAAoJEKeha0olJ0NqmCAH/3NtIQ27qKG+qRxjSfTN69PI VFXeebH9mA348b6uceFU4d3zLpTqZYv78vfVrhjOkEj/OW1ZHgacY6Zg6VpSvWHc 2jrRCy5p8JZG6weVYsqjQzUgMeOVQEYTih83k2UMu8sLFD6YNPdD6EbhBOgFXz06 65N6a3T/FaukvqCZTltRgdaauK7JhVZy7HgXdb/EgBpanc/3kfIU2pMd5IjR85z4 5AcrEhPnMCSGjP6tD2os2CP/5zX/j4VGVj5Ot17LeFAf6XA/65c95tmwixOZPRkk tvOduD1NJHhvJT8kd2Fg05pHnIbkvQee43/EtLRSZhHGtGgG9Rn5IpeHsTkW1Pk= =CI0+ -----END PGP SIGNATURE----- --FKmJ6Emd4GejmsmNnAmIJAUePpPnvqg91--