From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:35685) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ghUZH-0002FA-Ks for qemu-devel@nongnu.org; Thu, 10 Jan 2019 02:15:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ghUZC-0002U4-0p for qemu-devel@nongnu.org; Thu, 10 Jan 2019 02:15:52 -0500 References: <20180609151758.17343-1-vsementsov@virtuozzo.com> <20180609151758.17343-5-vsementsov@virtuozzo.com> <91a97b47-abab-4508-09d5-a12ddd1a4101@redhat.com> From: Eric Blake Message-ID: <4a689a27-645c-da07-4512-ba4ed7e212cb@redhat.com> Date: Thu, 10 Jan 2019 01:15:42 -0600 MIME-Version: 1.0 In-Reply-To: <91a97b47-abab-4508-09d5-a12ddd1a4101@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vOkk1BeywDlAKrvxVNOMiZSqoqkGK7QeS" Subject: Re: [Qemu-devel] [PATCH v5 4/6] nbd/server: implement dirty bitmap export List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: kwolf@redhat.com, pbonzini@redhat.com, den@openvz.org, armbru@redhat.com, mreitz@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --vOkk1BeywDlAKrvxVNOMiZSqoqkGK7QeS From: Eric Blake To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: kwolf@redhat.com, pbonzini@redhat.com, den@openvz.org, armbru@redhat.com, mreitz@redhat.com Message-ID: <4a689a27-645c-da07-4512-ba4ed7e212cb@redhat.com> Subject: Re: [PATCH v5 4/6] nbd/server: implement dirty bitmap export References: <20180609151758.17343-1-vsementsov@virtuozzo.com> <20180609151758.17343-5-vsementsov@virtuozzo.com> <91a97b47-abab-4508-09d5-a12ddd1a4101@redhat.com> In-Reply-To: <91a97b47-abab-4508-09d5-a12ddd1a4101@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 1/9/19 1:21 PM, Eric Blake wrote: > Revisiting an older thread: >=20 > On 6/9/18 10:17 AM, Vladimir Sementsov-Ogievskiy wrote: >> Handle new NBD meta namespace: "qemu", and corresponding queries: >> "qemu:dirty-bitmap:". >> >> With new metadata context negotiated, BLOCK_STATUS query will reply >> with dirty-bitmap data, converted to extents. New public function >> nbd_export_bitmap selects bitmap to export. For now, only one bitmap >> may be exported. >> >> + if (bdrv_dirty_bitmap_enabled(bm)) { >> + error_setg(errp, "Bitmap '%s' is enabled", bitmap); >> + return; >> + } >=20 > Why are we restricting things to only export disabled bitmaps? >=20 > I can understand the argument that if the image being exported is > read-only, then an enabled bitmap _that can be changed_ is probably a > bad idea (it goes against the notion of the export being read only). > But if we were to allow a writable access to an image, wouldn't we > expect that writes be reflected into the bitmap, which means permitting= > an enabled bitmap? I've now addressed this in my v2 Promote x-nbd-server-add-bitmap to stable series. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --vOkk1BeywDlAKrvxVNOMiZSqoqkGK7QeS Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEY3OaSlgimHGqKqRv3g5py3orov0FAlw28R4ACgkQ3g5py3or ov278wf/QGYgFveU6Jxd0NDP+iYYqcCP3KOeMqU2JGiY7nrrmPvT2wfyMW38P0or hWZ+3Qo4g10IQvFo2QOer77B3OF+HJEXL+2s+JZuOMLf+hQPcVYg6DI5M+wMGPwp upcMSBVcFEElqtXL2p1DXPFYy3NfpgIRP/3Kd4V1g+sMkURCc7x3tkMBG87Shyao ql8EGrXhT3PORJiErR6Jqf4i/D6TyyU4wvhA+mkZ3naPU5leqd/Xu2AKuKO4cauU YyTJ26CErLj1oVXEqkfV4UqAsyj/QOi4QcSonCblDbFl3vUlxZls8VAXLucAkAoA JV6XzVsmRIV5km+Vnhwk4IBDJbIHXg== =OBvK -----END PGP SIGNATURE----- --vOkk1BeywDlAKrvxVNOMiZSqoqkGK7QeS--