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Wed, 11 Sep 2019 07:37:22 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-116-94.ams2.redhat.com [10.36.116.94]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A203160BF7; Wed, 11 Sep 2019 07:37:20 +0000 (UTC) To: Kevin Wolf References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-23-mreitz@redhat.com> <20190910145229.GI4446@localhost.localdomain> <20190911065517.GA4907@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: Wed, 11 Sep 2019 09:37:18 +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: <20190911065517.GA4907@localhost.localdomain> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="1SwZw7Fa3nnB6EgvdN1OsVjUe1tSr6fK0" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Wed, 11 Sep 2019 07:37:22 +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 v6 22/42] block: Fix bdrv_get_allocated_file_size's fallback 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: Vladimir Sementsov-Ogievskiy , 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) --1SwZw7Fa3nnB6EgvdN1OsVjUe1tSr6fK0 Content-Type: multipart/mixed; boundary="olfXk1fQ18ht43IMWrf9iZgHQeKFOWSuh"; protected-headers="v1" From: Max Reitz To: Kevin Wolf Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, Vladimir Sementsov-Ogievskiy Message-ID: Subject: Re: [PATCH v6 22/42] block: Fix bdrv_get_allocated_file_size's fallback References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-23-mreitz@redhat.com> <20190910145229.GI4446@localhost.localdomain> <20190911065517.GA4907@localhost.localdomain> In-Reply-To: <20190911065517.GA4907@localhost.localdomain> --olfXk1fQ18ht43IMWrf9iZgHQeKFOWSuh Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 11.09.19 08:55, Kevin Wolf wrote: > Am 11.09.2019 um 08:20 hat Max Reitz geschrieben: >> On 10.09.19 16:52, Kevin Wolf wrote: >>> Am 09.08.2019 um 18:13 hat Max Reitz geschrieben: >>>> If the driver does not implement bdrv_get_allocated_file_size(), we >>>> should fall back to cumulating the allocated size of all non-COW >>>> children instead of just bs->file. >>>> >>>> Suggested-by: Vladimir Sementsov-Ogievskiy >>>> Signed-off-by: Max Reitz >>> >>> This smells like an overgeneralisation, but if we want to count all v= mdk >>> extents, the qcow2 external data file, etc. it's an improvement anywa= y. >>> A driver that has a child that should not be counted must just rememb= er >>> to implement the callback. >>> >>> Let me think of an example... How about quorum, for a change? :-) >>> Or the second blkverify child. >>> >>> Or eventually the block job filter nodes. >> >> I actually think it makes sense for all of these nodes to report the s= um >> of all of their children=E2=80=99s allocated sizes. >=20 > Hm... Yes, in a way. But not much more than it would make sense to > report the sum of the sizes of all images in the whole backing chain > (this is a useful thing to ask for, just maybe not the right thing to > return for a low-level interface). But I can accept that it's maybe a > bit more expected for quorum and blkverify than for COW images. >=20 > If you include the block job filter nodes, I have to disagree, though. > If mirror_top_bs (or any other job filter) sits in the middle of the > source chain, then I certainly don't want to see the target size added > to it. Hm, I don=E2=80=99t care much either way. I think it makes complete sens= e to add the target size there, but OTOH it=E2=80=99s only temporary while the= job runs, so it may be a bit confusing if it suddenly goes up and then down again. But I think this is the special case, so this is what should be handled in a driver callback. >> If a quorum node has three children with allocated sizes of 3 MB, 1 MB= , >> and 2 MB, respectively (totally possible if some have explicit zeroes >> and others don=E2=80=99t; it may also depend on the protocol, the file= system, >> etc.), then I think it makes most sense to report indeed 6 MB for the >> quorum subtree as a whole. What would you report? 3 MB? >=20 > Do it's the quorum way: Just vote! Add an option for it? Average, maximum, median, majority, sum? :-) > No, you're right, of course. -ENOTSUP is probably the only other thing > you could do then. >=20 >>> Ehm... Maybe I should just take back what I said first. It almost fee= ls >>> like it would be better if qcow2 and vmdk explicitly used a handler t= hat >>> counts all children (could still be a generic one in block.c) rather >>> than having to remember to disable the functionality everywhere where= we >>> don't want to have it. >> >> I don=E2=80=99t, because everywhere we don=E2=80=99t want this functio= nality, we still >> need to choose a child. This has to be done by the driver anyway. >=20 > Well, by default the primary child, which should cover like 90% of the > drivers? Hm, yes. But I still think that the drivers that do not want to count every single non-COW child are the exception. Max --olfXk1fQ18ht43IMWrf9iZgHQeKFOWSuh-- --1SwZw7Fa3nnB6EgvdN1OsVjUe1tSr6fK0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl14pC4ACgkQ9AfbAGHV z0C19gf/SnD0/QfeSzVhtr2oJFTrwe1ku7ScBFMO5RSYs7P+mjLxNm8qBS/6d4rM pKdXu21YsIdBE/Jw/aqVeXHwUn6OPaYQpHtRicttToXu0FBnRzcu30YTdbm6lhcV 8BWjLhMAZ7hHGUE0QFJGz1oNEFd1gIIn9C5Sush+mrMogTCVZ9Z8jPb0diyb5/gn XDEgAzwVqH/Qvixa8wyu6AG6tcjEI34bgAJapy2wHEHPiZbIu2eGSdnEb9zKtaZF S4Id1+ilIT1VSARq48XoYZRgHPm/yzZ9FYCB6KwBlWP6nxMS9EPIgIX43N+Fmkyh fSMqDP1G95goAjcnM8U3flPdbmbLMQ== =shrY -----END PGP SIGNATURE----- --1SwZw7Fa3nnB6EgvdN1OsVjUe1tSr6fK0--