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Thu, 26 Mar 2020 13:32:08 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-112-132.ams2.redhat.com [10.36.112.132]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6C4F45E001; Thu, 26 Mar 2020 13:32:07 +0000 (UTC) Subject: Re: [PATCH for-5.0 v2 0/4] bug fixes extracted from larger qcow2 zero bit work To: Eric Blake , qemu-devel@nongnu.org References: <20200324174233.1622067-1-eblake@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: <9017607c-7fa7-4f22-a424-e272edaba942@redhat.com> Date: Thu, 26 Mar 2020 14:32:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200324174233.1622067-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="IUqdR8ubwkaCIm8YXdl9bIytpshwqRrNG" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 216.205.24.74 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: kwolf@redhat.com, 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) --IUqdR8ubwkaCIm8YXdl9bIytpshwqRrNG Content-Type: multipart/mixed; boundary="Y9IXxbZJNH1GR3mykdq4mvxbmqJhwyvSe" --Y9IXxbZJNH1GR3mykdq4mvxbmqJhwyvSe Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 24.03.20 18:42, Eric Blake wrote: > My proposal [1] to add an autoclear all-zero-content bit to the qcow2 > format has now stalled into 5.1 territory, but several patches in my > initial proposal are uncontroversial and obvious bug fixes worth > having in 5.0. >=20 > [1] https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg08075.html >=20 > Eric Blake (4): > qcow2: Comment typo fixes > qcow2: List autoclear bit names in header > qcow2: Avoid feature name extension on small cluster size > sheepdog: Consistently set bdrv_has_zero_init_truncate OK, so my only real gripe was with the question whether we could make patch 3 decide dynamically when to include or not include the feature name table. There=E2=80=99s little difference in practice: Right now, we c= ould probably get away with including it in images with 4k clusters, then it would automatically switch to 8k clusters minimum (which is the limit chosen in patch 3 as-is), and at some theoretical point in the far, far future it would switch 16k clusters minimum. I don=E2=80=99t think anyone really cares about whether the feature name ta= ble is in images with 4k clusters or not, and I think we still have a couple of decades before we the table gets too big for images with 8k clusters (and we probably won=E2=80=99t be using qcow2 then anymore). So tl;dr: There=E2=80=99s no practical benefit of deciding dynamically, hen= ce I=E2=80=99m taking this series as-is: https://git.xanclic.moe/XanClic/qemu/commits/branch/block Thanks! Max --Y9IXxbZJNH1GR3mykdq4mvxbmqJhwyvSe-- --IUqdR8ubwkaCIm8YXdl9bIytpshwqRrNG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl58rtUACgkQ9AfbAGHV z0A01gf+MGZC8Ynj9wKKv1MGCmLLesXBs79p2Ndnx02l7cf6UlJVF9qikUR2GHer UiYlaeRX6H+q090xrlGaqiHlRS9DMrWbidQF8aY7+cS4jG70kehmOxVPexakDD26 zDp2tMvPXMjHvYWbpwYnHsuqk/7TNfrkSHGTYoQvHLwCI3UlSoNQ/Ddd7/ryNww3 iAYXuxWcGHtW6MZT8aHnbz3YsNfL/colzXBUV0vNqhD62j7NMw3qcvQes5EMI+px 6Th0M365N34JoPkfTMMiT2TVWFDUYADYS2CK+NEf5WZDQGr6Na6G9wBXEtEOxPw2 qmriduGJVhkFRWauAv7GikaXaUNk4g== =dNGS -----END PGP SIGNATURE----- --IUqdR8ubwkaCIm8YXdl9bIytpshwqRrNG--