From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58414) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uz8Xy-0005M0-NL for qemu-devel@nongnu.org; Tue, 16 Jul 2013 12:56:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uz8Xx-0005wv-9A for qemu-devel@nongnu.org; Tue, 16 Jul 2013 12:56:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33716) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uz8Xx-0005wT-08 for qemu-devel@nongnu.org; Tue, 16 Jul 2013 12:56:17 -0400 Message-ID: <51E57B2A.7050100@redhat.com> Date: Tue, 16 Jul 2013 10:56:10 -0600 From: Eric Blake MIME-Version: 1.0 References: <1373992168-26043-1-git-send-email-pbonzini@redhat.com> In-Reply-To: <1373992168-26043-1-git-send-email-pbonzini@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="----enig2DQXBIRTIISHGEGIFHNNI" Subject: Re: [Qemu-devel] [PATCH v2 00/17] Add qemu-img subcommand to dump file metadata List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: famz@redhat.com, pl@kamp.de, qemu-devel@nongnu.org, stefanha@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2DQXBIRTIISHGEGIFHNNI Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 07/16/2013 10:29 AM, Paolo Bonzini wrote: > This series adds a subcommand to "map" that can dump file metadata. > Metadata that is dumped includes: >=20 > - whether blocks are allocated in bs->file and, if so, where >=20 > - whether blocks are zero >=20 > - whether data is read from bs or bs->backing_hd Is this command only usable from qemu-img, or is there a QMP counterpart for getting at the same information on a live image while qemu is running= ? >=20 > Metadata is dumped for an entire chain of images. One example usage is= > (for non-compressed, non-encrypted images) to transform the metadata > into a Linux device-mapper setup, and make a qcow2 image available (for= > read only) as a block device. Another possible usage is to determine > the used areas of a file, and convert it in place to another format. > Alternatively, the richer data can be used by block jobs to quickly > determine if a block is zero without reading it. Definitely useful information! I haven't looked at the implementation yet, but there had better be a JSON representation of the output :) --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org ------enig2DQXBIRTIISHGEGIFHNNI Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJR5XsqAAoJEKeha0olJ0Nqi8gIAJulWtiXYEPcAqbVQUMAvQqC zu6eblPTM7XJdCNCt5003ScgNvV8CfG0jHjYN3Y7TtQGsVpKaGTNXAYIgcUP4Sp4 /MfFzBs2beE+EKt3elWbG0V+LDDonFcqbqc/f9j9luNqsoJtu/JbRST8xFeHI+c0 lUprzOQ5qWewFw+DJ8y08IqlJk00rnUYoAlNZBn8BfNT3jRBapiJY9QCJVtotWwu NlsXz1e+UwBOMIi4KN2crDk7GvmWHFKO9VbKK3UkMH6Ohd5hSh+u45VONDJcIKzf c2ltociU8IyJjFyheawwDkxcoGdzAJSsEEQj9pnjmq+PhDmT4JY7Aphio0JpS1A= =Xbxt -----END PGP SIGNATURE----- ------enig2DQXBIRTIISHGEGIFHNNI--