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Mon, 12 Aug 2019 19:07:18 +0000 (UTC) To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" References: <20190725155512.9827-1-mreitz@redhat.com> <20190725155512.9827-4-mreitz@redhat.com> <627fbb64-5ffe-aca7-6198-9d991d4219e3@virtuozzo.com> 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: Mon, 12 Aug 2019 21:07:17 +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: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="N4UvEtEy1niSNF0yWAKVEC2p65o8ZsnA9" 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 [10.5.110.25]); Mon, 12 Aug 2019 19:07:20 +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 3/3] vpc: Do not return RAW from block_status 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 , "qemu-devel@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) --N4UvEtEy1niSNF0yWAKVEC2p65o8ZsnA9 Content-Type: multipart/mixed; boundary="liNzYjQmliiZ6oztyIQnPlZ0W1Ex1B02S"; protected-headers="v1" From: Max Reitz To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" Cc: "qemu-devel@nongnu.org" , Kevin Wolf Message-ID: Subject: Re: [PATCH 3/3] vpc: Do not return RAW from block_status References: <20190725155512.9827-1-mreitz@redhat.com> <20190725155512.9827-4-mreitz@redhat.com> <627fbb64-5ffe-aca7-6198-9d991d4219e3@virtuozzo.com> In-Reply-To: --liNzYjQmliiZ6oztyIQnPlZ0W1Ex1B02S Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 12.08.19 18:50, Vladimir Sementsov-Ogievskiy wrote: > 12.08.2019 18:56, Max Reitz wrote: >> On 12.08.19 17:33, Vladimir Sementsov-Ogievskiy wrote: >>> 25.07.2019 18:55, Max Reitz wrote: >>>> vpc is not really a passthrough driver, even when using the fixed >>>> subformat (where host and guest offsets are equal). It should handl= e >>>> preallocation like all other drivers do, namely by returning >>>> DATA | RECURSE instead of RAW. >>>> >>>> There is no tangible difference but the fact that bdrv_is_allocated(= ) no >>>> longer falls through to the protocol layer. >>> >>> Hmm. Isn't a real bug (fixed by this patch) ? >>> >>> Assume vpc->file is qcow2 with backing, which have "unallocated" regi= on, which is >>> backed by actual data in backing file. >> >> Come on now. >> >>> So, this region will be reported as not allocated and will be skipped= by any copying >>> loop using block-status? Is it a bug of BDRV_BLOCK_RAW itself? Or I d= on't understand >>> something.. >> >> I think what you don=E2=80=99t understand is that if you have a vpc fi= le inside >> of a qcow2 file, you=E2=80=99re doing basically everything wrong. ;-) >> >> But maybe we should drop BDRV_BLOCK_RAW... Does it do anything good f= or >> us in the raw driver? Shouldn=E2=80=99t it too just return DATA | REC= URSE? >> >=20 > And if I have raw driver above qcow2, it will not work, like I've descr= ibed above.. Yep. That=E2=80=99s why I was wondering. (This is a more likely case, b= ecause maybe you really want to use raw=E2=80=99s offset capability on top of qc= ow2.) Max --liNzYjQmliiZ6oztyIQnPlZ0W1Ex1B02S-- --N4UvEtEy1niSNF0yWAKVEC2p65o8ZsnA9 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1RuOUACgkQ9AfbAGHV z0ANHAgAkmkPKd0A8vhtEJ1Xeit7caluFajsIb25oaZ2NMWW03S0KZ/XW2sReSUw ue1Rwv9Zk2Q/zqjekckO4Qb8d32VD2kWCNs3+9vb6mtp/kVLhcl3zv/3fUKCgbZe ixgFYujgcMFx/Pm7Yt91+GG8fiH/aZX+Q5EsSk+CPnSiVi72fbIsaNfYIgn2R2Pk Cn4zeXLUW25zGMKBXniZWn7LRmlzSHEoCT1MxzJAcCmH8wnIdPjqd/xoaJmiyrVn y7l2J1CLMOs579VeuXAIRpCrl0Fr2IxOo7nfdEaqVllv8rlG2wnpyZvgYMm9bmib 8l97i1O0iuN0bD2SPr82VMd2GyX1OQ== =5RCB -----END PGP SIGNATURE----- --N4UvEtEy1niSNF0yWAKVEC2p65o8ZsnA9--