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Thu, 20 Feb 2020 17:22:19 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.36.118.38]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EA21160BE2; Thu, 20 Feb 2020 17:21:43 +0000 (UTC) Subject: Re: [RFC PATCH v3 11/27] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type() To: Alberto Garcia , qemu-devel@nongnu.org References: <124dca3e5be368048346209754fec38dff404990.1577014346.git.berto@igalia.com> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <80213b27-539f-0ab1-9983-16b5bb16d666@redhat.com> Date: Thu, 20 Feb 2020 18:21:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <124dca3e5be368048346209754fec38dff404990.1577014346.git.berto@igalia.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0wlkcUsGiWYusKYA4hNv9jk7lR0r8FKbF" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Anton Nefedov , qemu-block@nongnu.org, Vladimir Sementsov-Ogievskiy , "Denis V . Lunev" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --0wlkcUsGiWYusKYA4hNv9jk7lR0r8FKbF Content-Type: multipart/mixed; boundary="vHYRoq7rADxc9SQdLmel59xFgeGT55DzV" --vHYRoq7rADxc9SQdLmel59xFgeGT55DzV Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 22.12.19 12:36, Alberto Garcia wrote: > This patch adds QCow2SubclusterType, which is the subcluster-level > version of QCow2ClusterType. All QCOW2_SUBCLUSTER_* values have the > the same meaning as their QCOW2_CLUSTER_* equivalents (when they > exist). See below for details and caveats. >=20 > In images without extended L2 entries clusters are treated as having > exactly one subcluster so it is possible to replace one data type with > the other while keeping the exact same semantics. >=20 > With extended L2 entries there are new possible values, and every > subcluster in the same cluster can obviously have a different > QCow2SubclusterType so functions need to be adapted to work on the > subcluster level. >=20 > There are several things that have to be taken into account: >=20 > a) QCOW2_SUBCLUSTER_COMPRESSED means that the whole cluster is > compressed. We do not support compression at the subcluster > level. >=20 > b) There are two different values for unallocated subclusters: > QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN which means that the whole > cluster is unallocated, and QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC > which means that the cluster is allocated but the subcluster is > not. The latter can only happen in images with extended L2 > entries. >=20 > c) QCOW2_SUBCLUSTER_INVALID is used to detect the cases where an L2 > entry has a value that violates the specification. The caller is > responsible for handling these situations. >=20 > To prevent compatibility problems with images that have invalid > values but are currently being read by QEMU without causing side > effects, QCOW2_SUBCLUSTER_INVALID is only returned for images > with extended L2 entries. >=20 > qcow2_cluster_to_subcluster_type() is added as a separate function > from qcow2_get_subcluster_type(), but this is only temporary and both > will be merged in a subsequent patch. >=20 > Signed-off-by: Alberto Garcia > --- > block/qcow2.h | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 92 insertions(+) With the comment style fixed as now required by the coding style (/* and */ on separate lines), and regardless of the bit ordering: Reviewed-by: Max Reitz --vHYRoq7rADxc9SQdLmel59xFgeGT55DzV-- --0wlkcUsGiWYusKYA4hNv9jk7lR0r8FKbF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl5OwCIACgkQ9AfbAGHV z0DKFwgAo7jqyvORkt42xU20+EL7iC3NFFN6ZisakGpSEi1n0sbLRbXblmkcZbYJ kJPWV92Kx7Nmhsyp5oF9lH+5OkOxW1cCQCOr6B6GIG8E9p077TfTdwvdIt7IgjVW xHuXkCyNF6fKbU4nOa3rJBFeS5cq0d59ltS/ZsQvmP4I3uAJ/IugAcXfqV0Rh81r Cx5kBgQU2sCmpPNjoA1iRWHyPy1jt8jEXZ2p7eEi+YCS6UKssDou1M8+5M93j9I2 GUAwtrBzwzv+5zs/JVtEtgWkEj6HaRLPMrTco9XMsTX14AsRHn4OIwxPgDS7Dztj e17ah/Fc2Ev0+cd5apupcvmm2vjRyA== =jbWO -----END PGP SIGNATURE----- --0wlkcUsGiWYusKYA4hNv9jk7lR0r8FKbF--