From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34579) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f3iO4-00046h-MJ for qemu-devel@nongnu.org; Wed, 04 Apr 2018 09:23:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f3iO0-0003Pi-KU for qemu-devel@nongnu.org; Wed, 04 Apr 2018 09:23:40 -0400 Date: Wed, 4 Apr 2018 14:23:32 +0100 From: Stefan Hajnoczi Message-ID: <20180404132332.GR4467@stefanha-x1.localdomain> References: <20180329110914.20888-1-famz@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9uazBBczf8QSjDPd" Content-Disposition: inline In-Reply-To: <20180329110914.20888-1-famz@redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [RFC PATCH 0/8] qemu-img convert with copy offloading List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org, Kevin Wolf , qemu-block@nongnu.org, Max Reitz , Stefan Hajnoczi , pbonzini@redhat.com --9uazBBczf8QSjDPd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Mar 29, 2018 at 07:09:06PM +0800, Fam Zheng wrote: > [Posting a preview RFC for the general idea discussion and internal API r= eview. > Libiscsi support is being worked on in the meantime.] >=20 > This series introduces block layer API for copy offloading and makes use = of it > in qemu-img convert. >=20 > For now we implemented the operation in local file protocol with > copy_file_range(2). Besides that it's possible to add similar to iscsi, = nfs > and potentially more. >=20 > As far as its usage goes, in addition to qemu-img convert, we can emulate > offloading in scsi-disk (EXTENDED COPY), and do similar to drive-mirror. >=20 > The new bdrv_co_map_range can also be an alternative way to implement for= mat > drivers in the future, once we make block/io.c use it in preadv/pwritev p= aths. I posted concerns about the bdrv_co_map_range() interface. It would be safer to only have a copy_range() interface without exposing how data is mapped outside the driver where race conditions can occur and the format driver no longer has full control over file layout. Stefan --9uazBBczf8QSjDPd Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJaxNHUAAoJEJykq7OBq3PI35AH/0tPZRmp2X/8pbHc+/wsW7VN Djxli4Xofdgcdiu2yrR+Ik45JNU6Q0irrlHabxdwZ8ByltpTrY0XpAJXhoVv38UF hEmv3YE1zaenUGXkvxe851lCI4FqWkJ7O89+vNRV0JvW2Q7ql+mwR3jHtsnbdHGR v96x8b0yaICt/nyahvDl6HHudnZfORc+ym8vPelXt0GEVJTZFNwCI+qGTBET8mZE FooU7LDD+9n64saQHvhWaGxjJl3moyA//R5wXJsIcjHalQnz76wieMyALdzrjOD5 WNdQsNYdV170HMINYA/9gAk5VieFS4umvEg6462J05V4P/8c+43+ognJAVtABbI= =OeZS -----END PGP SIGNATURE----- --9uazBBczf8QSjDPd--