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Tue, 13 Aug 2019 14:43:52 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.40.205.136]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BB4413484C; Tue, 13 Aug 2019 14:43:50 +0000 (UTC) To: Kevin Wolf , Vladimir Sementsov-Ogievskiy References: <20190812181146.26121-1-vsementsov@virtuozzo.com> <20190812181146.26121-2-vsementsov@virtuozzo.com> <20190813110428.GE4663@localhost.localdomain> From: Max Reitz Openpgp: preference=signencrypt 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: Date: Tue, 13 Aug 2019 16:43:48 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190813110428.GE4663@localhost.localdomain> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="QDI3kMsPK9qVnBP1gUBMVAIa6MJR9weSp" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 13 Aug 2019 14:43:52 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 1/2] block/raw-format: switch to BDRV_BLOCK_DATA with BDRV_BLOCK_RECURSE 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: den@openvz.org, qemu-devel@nongnu.org, qemu-block@nongnu.org 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) --QDI3kMsPK9qVnBP1gUBMVAIa6MJR9weSp Content-Type: multipart/mixed; boundary="vHkyHna57nROrp8wgFgWykhKHMdNOKQVC"; protected-headers="v1" From: Max Reitz To: Kevin Wolf , Vladimir Sementsov-Ogievskiy Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, den@openvz.org Message-ID: Subject: Re: [PATCH 1/2] block/raw-format: switch to BDRV_BLOCK_DATA with BDRV_BLOCK_RECURSE References: <20190812181146.26121-1-vsementsov@virtuozzo.com> <20190812181146.26121-2-vsementsov@virtuozzo.com> <20190813110428.GE4663@localhost.localdomain> In-Reply-To: <20190813110428.GE4663@localhost.localdomain> --vHkyHna57nROrp8wgFgWykhKHMdNOKQVC Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 13.08.19 13:04, Kevin Wolf wrote: > Am 12.08.2019 um 20:11 hat Vladimir Sementsov-Ogievskiy geschrieben: >> BDRV_BLOCK_RAW makes generic bdrv_co_block_status to fallthrough to >> returned file. But is it correct behavior at all? If returned file >> itself has a backing file, we may report as totally unallocated and >> area which actually has data in bottom backing file. >> >> So, mirroring of qcow2 under raw-format is broken. Which is illustrate= d >> by following commit with a test. Let's make raw-format behave more >> correctly returning BDRV_BLOCK_DATA. >> >> Suggested-by: Max Reitz >> Signed-off-by: Vladimir Sementsov-Ogievskiy = >=20 > After some reading, I think I came to the conclusion that RAW is the > correct thing to do. There is indeed a problem, but this patch is tryin= g > to fix it in the wrong place. >=20 > In the case where the backing file contains some data, and we have a > 'raw' node above the qcow2 overlay node, the content of the respective > block is not defined by the queried backing file layer, so it is > completely correct that bdrv_is_allocated() returns false,like it would= > if you queried the qcow2 layer directly. I disagree. The queried backing file layer is the raw node. As I said, in my opinion raw nodes are not filter nodes, neither in behavior (they have an offset option), nor in how they are generally used (as a format).= The raw format does not support backing files. Therefore, everything on a raw node is allocated. (That is, like, my opinion.) > If it returned true, we would > copy everything, which isn't right either (the test cases should may ad= d > the qemu-img map output of the target so this becomes visible). It is right. Max --vHkyHna57nROrp8wgFgWykhKHMdNOKQVC-- --QDI3kMsPK9qVnBP1gUBMVAIa6MJR9weSp Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1SzKQACgkQ9AfbAGHV z0D1oAf9F8CE6jsyHHnSTMbN5z+KV0eHnoXS600/TPy9IlsiHw+ytZhsln3RqAYL WnrrAeaOL8W92ea3wEpzU0KdInbUTA1PIlbhjPMLXgFNo7AJ0ZjIoZo0JDapGZDF UPDXDthJ3OB5JiSUQjYHbv4uCmU6Tvyp7wzrN3Ciiu0FFaKvbWKKe8GZOV1O4Mmx uT2T5AuIY7hv61d2HLz2I+ToiGkxTusGJjxQAelbzvwxIpyccSx1xj1Lf6d6PS3u fkyCR0nCqgc6vV7AhyyF+IFiGup8anSqn5QKmB7hB4dwUfr1fXgajFlTE5Vkursc Y+uFbulW+H5yT2Q5NCEQzw0iSjJ+Wg== =4jtA -----END PGP SIGNATURE----- --QDI3kMsPK9qVnBP1gUBMVAIa6MJR9weSp--