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Mon, 12 Aug 2019 19:15:41 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-204-161.brq.redhat.com [10.40.204.161]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E93B65C548; Mon, 12 Aug 2019 19:15:39 +0000 (UTC) To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-23-mreitz@redhat.com> <4a2b0a48-5ee0-85b7-7519-a3633cefd803@redhat.com> <994ec2e4-23fe-58d2-bc4e-120ec1e89d25@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: <42ba1ef7-0073-42f6-76f1-b3537f56f96b@redhat.com> Date: Mon, 12 Aug 2019 21:15:38 +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: <994ec2e4-23fe-58d2-bc4e-120ec1e89d25@virtuozzo.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="CKHfB6n1nD2Gla4h4W2jXNyq70y7wtfZv" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 12 Aug 2019 19:15:41 +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: 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) --CKHfB6n1nD2Gla4h4W2jXNyq70y7wtfZv Content-Type: multipart/mixed; boundary="ZTODKkm6ryCmxaomHX9jH8rf8o48mB8HC"; protected-headers="v1" From: Max Reitz To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" Cc: "qemu-devel@nongnu.org" , Kevin Wolf Message-ID: <42ba1ef7-0073-42f6-76f1-b3537f56f96b@redhat.com> 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> <4a2b0a48-5ee0-85b7-7519-a3633cefd803@redhat.com> <994ec2e4-23fe-58d2-bc4e-120ec1e89d25@virtuozzo.com> In-Reply-To: <994ec2e4-23fe-58d2-bc4e-120ec1e89d25@virtuozzo.com> --ZTODKkm6ryCmxaomHX9jH8rf8o48mB8HC Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 12.08.19 19:14, Vladimir Sementsov-Ogievskiy wrote: > 12.08.2019 16:09, Max Reitz wrote: >> On 10.08.19 18:41, Vladimir Sementsov-Ogievskiy wrote: >>> 09.08.2019 19:13, Max Reitz wrote: >>>> 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 >>>> --- >>>> block.c | 22 ++++++++++++++++++++-- >>>> 1 file changed, 20 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/block.c b/block.c >>>> index 1070aa1ba9..6e1ddab056 100644 >>>> --- a/block.c >>>> +++ b/block.c >>>> @@ -4650,9 +4650,27 @@ int64_t bdrv_get_allocated_file_size(BlockDri= verState *bs) >>>> if (drv->bdrv_get_allocated_file_size) { >>>> return drv->bdrv_get_allocated_file_size(bs); >>>> } >>>> - if (bs->file) { >>>> - return bdrv_get_allocated_file_size(bs->file->bs); >>>> + >>>> + if (!QLIST_EMPTY(&bs->children)) { >>>> + BdrvChild *child; >>>> + int64_t child_size, total_size =3D 0; >>>> + >>>> + QLIST_FOREACH(child, &bs->children, next) { >>>> + if (child =3D=3D bdrv_filtered_cow_child(bs)) { >>>> + /* Ignore COW backing files */ >>>> + continue; >>>> + } >>>> + >>>> + child_size =3D bdrv_get_allocated_file_size(child->bs);= >>>> + if (child_size < 0) { >>>> + return child_size; >>>> + } >>>> + total_size +=3D child_size; >>>> + } >>>> + >>>> + return total_size; >>>> } >>>> + >>>> return -ENOTSUP; >>>> } >>>> =20 >>>> >>> >>> Hmm.. >>> >>> 1. No children -> -ENOTSUP >>> 2. Only cow child -> 0 >>> 3. Some non-cow children -> SUM >>> >>> It's all arguable (the strictest way is -ENOTSUP in either case), >>> but if we want to fallback to SUM of non-cow children, 1. and 2. shou= ld return >>> the same. >> >> I don=E2=80=99t think 2 is possible at all. If you have a COW child, = you need >> some other child to COW to. >> >> And in the weird (and probably impossible) case where a node really on= ly >> has a COW child, I=E2=80=99d say it=E2=80=99s correct that it has a di= sk size of 0 =E2=80=93 >> because it hasn=E2=80=99t COWed anything yet. (Just like a new qcow2 = image with >> a backing file only has its metadata as its disk size.) >> >=20 > Agreed. Then, why not return 0 on [1] ? (1) Because that=E2=80=99s the current behavior. :-) (2) Nodes that have no children are protocol nodes. Protocol nodes (apart from null) still have to store their data somewhere. Therefore, they must implement .bdrv_get_allocated_file_size() to report that. If they don=E2=80=99t, that doesn=E2=80=99t mean they don=E2=80=99t store an= y data, but only that we don=E2=80=99t know how much data they store. > Also, another idea: shouldn't we return 0 for filters, i.e. skip filter= ed_rw_child too? > [as filtered-child is more like backing child than file one, it's "less= owned" by its parent] Why would we do that? If I have a block device with a throttle node attached to it and request how much space it uses, of course I will want to know how much space the whole tree below it uses. (Otherwise, bdrv_get_allocated_file_size() should only report anything for protocol nodes, and 0 for everything else.) Max > with or without any of these suggestions: > Reviewed-by: Vladimir Sementsov-Ogievskiy --ZTODKkm6ryCmxaomHX9jH8rf8o48mB8HC-- --CKHfB6n1nD2Gla4h4W2jXNyq70y7wtfZv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1RutoACgkQ9AfbAGHV z0D6WwgAhPQXJJpuknuRDiAF6GI5pQksvvNy7AVbl+Dsi5L4Xi10bWYFf8p1Q4mW e529Ha0IjQiPrDwQW2gI6MRmpRV8p8JHqOlpHlY+tCfVxYDveYz7pbHjNOfG1g+J z6d4ryi4mEjRIvev1bRusqzg2sDkkrC+OSSLCCxa7/Rhpo64ncyUv2Q8pTOy6rgh PPAyiwdWx384W22Yexvk0IrFzQyepGzmHzE0LEYP6DNQwpfmivB5OuweGKT+PUxR pmG6279zcWs+9e0WdOkC2RYeGN4NpoY/16m3NSVxiw+7zBzgjBimWp0gNQY4EOpR elim0Zzy6nDMWPnREXHO8BrAjorTFw== =3IAy -----END PGP SIGNATURE----- --CKHfB6n1nD2Gla4h4W2jXNyq70y7wtfZv--