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Thu, 19 Dec 2019 12:46:15 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-205-138.brq.redhat.com [10.40.205.138]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 27C5A63B94; Thu, 19 Dec 2019 12:46:14 +0000 (UTC) Subject: Re: [PATCH 1/3] block: Activate recursively even for already active nodes To: Kevin Wolf , qemu-block@nongnu.org References: <20191217145939.5537-1-kwolf@redhat.com> <20191217145939.5537-2-kwolf@redhat.com> From: Max Reitz 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: Thu, 19 Dec 2019 13:46:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191217145939.5537-2-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ZRddNMxetXLDbIZPXf1VoQazoGMxB3nD1" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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 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) --ZRddNMxetXLDbIZPXf1VoQazoGMxB3nD1 Content-Type: multipart/mixed; boundary="E1OA5HAnYu1gTQxy5DwghMO9fUfEgrMmf" --E1OA5HAnYu1gTQxy5DwghMO9fUfEgrMmf Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 17.12.19 15:59, Kevin Wolf wrote: > bdrv_invalidate_cache_all() assumes that all nodes in a given subtree > are either active or inactive when it starts. Therefore, as soon as it > arrives at an already active node, it stops. >=20 > However, this assumption is wrong. For example, it's possible to take a > snapshot of an inactive node, which results in an active overlay over an > inactive backing file. The active overlay is probably also the root node > of an inactive BlockBackend (blk->disable_perm =3D=3D true). >=20 > In this case, bdrv_invalidate_cache_all() does not need to do anything > to activate the overlay node, but it still needs to recurse into the > children and the parents to make sure that after returning success, > really everything is activated. >=20 > Signed-off-by: Kevin Wolf > --- > block.c | 50 ++++++++++++++++++++++++-------------------------- > 1 file changed, 24 insertions(+), 26 deletions(-) Basically the only change is to not skip the whole function when the node is already active but only the part that actually activates the node. blk_root_activate() is a no-op for already-active BBs, so this looks good to me. Reviewed-by: Max Reitz --E1OA5HAnYu1gTQxy5DwghMO9fUfEgrMmf-- --ZRddNMxetXLDbIZPXf1VoQazoGMxB3nD1 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl37cRUACgkQ9AfbAGHV z0DcLQgAvJW0tqYwYz22hMT/QG24rlqq6objMA2l3Fkjrcxy3aXmjMR4ovOXP9R1 BoT2qTG/abV5QiFHPhA7vdp01VDf4vtOR7LxzSDDo++OE/NE589XXh/2K7BsF4YD eA0XORhRdrE7dQaXb2m+e1YTUbgCl9ol921j1xIVMdqbA37Lg5E7u2gUqhgAp0kC uY2kfH5p+hbOxpwEiF4F9wPkt2aza0wCZDwGZ7gUUY3gZ+VZ3LUl3VpRacqiCozg 1cABAfcaVXhhxwXZjrvvrOFK7g7tUOAGaOBDZbxDeaoyw+LopwhYFRTOl7/jVokn TWXRsaNwiszbvLyS773QVrLPlWZx2g== =4x0n -----END PGP SIGNATURE----- --ZRddNMxetXLDbIZPXf1VoQazoGMxB3nD1--