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Wed, 17 Jul 2019 07:47:43 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.40.205.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F0D175C21A; Wed, 17 Jul 2019 07:47:41 +0000 (UTC) To: Kevin Wolf References: <20190703172813.6868-1-mreitz@redhat.com> <20190703172813.6868-7-mreitz@redhat.com> <20190716170156.GJ7297@linux.fritz.box> 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: <22745e99-6b6e-53d5-91b7-e1156782e55e@redhat.com> Date: Wed, 17 Jul 2019 09:47:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190716170156.GJ7297@linux.fritz.box> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Ca9n3kqhwZInyDlDFcIBH7ejIohUqwoA1" 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 [10.5.110.29]); Wed, 17 Jul 2019 07:47:43 +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 v2 06/12] block: Deep-clear inherits_from 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: 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) --Ca9n3kqhwZInyDlDFcIBH7ejIohUqwoA1 Content-Type: multipart/mixed; boundary="6mMh1hJ05O5ZEisht4c2n3Apmym1xaOtE"; protected-headers="v1" From: Max Reitz To: Kevin Wolf Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org Message-ID: <22745e99-6b6e-53d5-91b7-e1156782e55e@redhat.com> Subject: Re: [PATCH v2 06/12] block: Deep-clear inherits_from References: <20190703172813.6868-1-mreitz@redhat.com> <20190703172813.6868-7-mreitz@redhat.com> <20190716170156.GJ7297@linux.fritz.box> In-Reply-To: <20190716170156.GJ7297@linux.fritz.box> --6mMh1hJ05O5ZEisht4c2n3Apmym1xaOtE Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 16.07.19 19:01, Kevin Wolf wrote: > Am 03.07.2019 um 19:28 hat Max Reitz geschrieben: >> BDS.inherits_from does not always point to an immediate parent node. >> When launching a block job with a filter node, for example, the node >> directly below the filter will not point to the filter, but keep its o= ld >> pointee (above the filter). >> >> If that pointee goes away while the job is still running, the node's >> inherits_from will not be updated and thus point to garbage. To fix >> this, bdrv_unref_child() has to check not only the parent node's >> immediate children for nodes whose inherits_from needs to be cleared, >> but its whole subtree. >> >> Signed-off-by: Max Reitz >=20 > Isn't the real bug that we keep pointing to a node that isn't a parent > of the node any more? I think this will effectively disable option > inheritance in bdrv_reopen() as long as the filter node is present, > which is certainly not what we intended. Well, it breaks it while a block job is running. I don=E2=80=99t know wh= ether I would advise doing a reopen across a block job filter. It=E2=80=99s a ca= se of =E2=80=9CWhy wouldn=E2=80=99t it work?=E2=80=9D, but I=E2=80=99m sure the= re=E2=80=99s something that doesn=E2=80=99t. (Like this here, for example, but it at least has the decency of just letting the reopen fail.) > The intuitive thing would be that after inserting a filter, the image > now inherits from the filter node, and when the filter is removed, it > inherits from the filter's bs->inherit_from if that becomes a parent of= > the node. (Though I'm not necessarily saying that my intuition is to be= > trusted here.) I tried that first, but I couldn=E2=80=99t get it to work. I don=E2=80=99= t remember why, though. I suppose my problem was that removing the filter node make inherits_from NULL. I guess I stopped at that point and went this route instead. I suppose we could add a flag to the BDS that says whether an heir node=E2=80=99s inherits_from should be cleared or set to the bequeather=E2= =80=99s inherits_from, like so: if (parent->inherit_inherits_from) { child->bs->inherits_from =3D parent->inherits_from; } else { child->bs->inherits_from =3D NULL; } And then, if you insert a node between a child and its inherits_from parent, that node copies inherits_from from the child and gets its inherit_inherits_from set to true. The problem I see is that it doesn=E2=80=99t always appear clear to me th= at this intermediate node should actually copy its inherits_from from the child. So the same question applies here, too, I guess; should the filter node even inherit its options from the parent? Max --6mMh1hJ05O5ZEisht4c2n3Apmym1xaOtE-- --Ca9n3kqhwZInyDlDFcIBH7ejIohUqwoA1 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl0u0psACgkQ9AfbAGHV z0DKUgf/U9L1FCJx+Y0MhXKCm+vKNy/HBLSZ+vudMG1Wmcnlt/AeWyoQdklFezo0 +H3P+D/KKMg5rIIDRrrYcgqFuAWtep2f2bH/RI56RIVlENPXCOUNx3IW7nrVhaUy ivbHxt6omLk76XcuxDcJwjImomc5KZkGBs7gTNl3Y9ToR1VcOQQsgRBzOWr1n9u+ 1ktzp6IpUuaJHJhaCahqKu7UGnVIjGzv3dwaXVfUH1kw7B22GYaeo9Yj+PeCjWka gY1HpEQIoNLOryoJoitVaqzYxA10BkrSHOsxgN89sybjiWXJFKC4It/sw7iBVvGp oMv3Aj0+yn9MGdZaOJXzK0r6Sgfmqw== =QvWm -----END PGP SIGNATURE----- --Ca9n3kqhwZInyDlDFcIBH7ejIohUqwoA1--