From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F588C2BCA1 for ; Fri, 7 Jun 2019 19:53:49 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E2D6C208C3 for ; Fri, 7 Jun 2019 19:53:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E2D6C208C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52524 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hZKvr-00008F-V3 for qemu-devel@archiver.kernel.org; Fri, 07 Jun 2019 15:53:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46967) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hZJOf-0001Sh-Ad for qemu-devel@nongnu.org; Fri, 07 Jun 2019 14:15:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hZJOe-00030e-3r for qemu-devel@nongnu.org; Fri, 07 Jun 2019 14:15:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33698) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hZJOb-0002tw-EH; Fri, 07 Jun 2019 14:15:21 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3714B307D854; Fri, 7 Jun 2019 18:15:14 +0000 (UTC) Received: from [10.3.116.85] (ovpn-116-85.phx2.redhat.com [10.3.116.85]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 654092B027; Fri, 7 Jun 2019 18:15:06 +0000 (UTC) To: John Snow , Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" , "qemu-devel@nongnu.org" References: <20190606184159.979-1-jsnow@redhat.com> <20190606184159.979-3-jsnow@redhat.com> <70a53585-bdc6-1877-01f5-1b2d1aad8de6@virtuozzo.com> From: Eric Blake Openpgp: preference=signencrypt Autocrypt: addr=eblake@redhat.com; keydata= xsBNBEvHyWwBCACw7DwsQIh0kAbUXyqhfiKAKOTVu6OiMGffw2w90Ggrp4bdVKmCaEXlrVLU xphBM8mb+wsFkU+pq9YR621WXo9REYVIl0FxKeQo9dyQBZ/XvmUMka4NOmHtFg74nvkpJFCD TUNzmqfcjdKhfFV0d7P/ixKQeZr2WP1xMcjmAQY5YvQ2lUoHP43m8TtpB1LkjyYBCodd+LkV GmCx2Bop1LSblbvbrOm2bKpZdBPjncRNob73eTpIXEutvEaHH72LzpzksfcKM+M18cyRH+nP sAd98xIbVjm3Jm4k4d5oQyE2HwOur+trk2EcxTgdp17QapuWPwMfhaNq3runaX7x34zhABEB AAHNHkVyaWMgQmxha2UgPGVibGFrZUByZWRoYXQuY29tPsLAegQTAQgAJAIbAwULCQgHAwUV CgkICwUWAgMBAAIeAQIXgAUCS8fL9QIZAQAKCRCnoWtKJSdDahBHCACbl/5FGkUqJ89GAjeX RjpAeJtdKhujir0iS4CMSIng7fCiGZ0fNJCpL5RpViSo03Q7l37ss+No+dJI8KtAp6ID+PMz wTJe5Egtv/KGUKSDvOLYJ9WIIbftEObekP+GBpWP2+KbpADsc7EsNd70sYxExD3liwVJYqLc Rw7so1PEIFp+Ni9A1DrBR5NaJBnno2PHzHPTS9nmZVYm/4I32qkLXOcdX0XElO8VPDoVobG6 gELf4v/vIImdmxLh/w5WctUpBhWWIfQDvSOW2VZDOihm7pzhQodr3QP/GDLfpK6wI7exeu3P pfPtqwa06s1pae3ad13mZGzkBdNKs1HEm8x6zsBNBEvHyWwBCADGkMFzFjmmyqAEn5D+Mt4P zPdO8NatsDw8Qit3Rmzu+kUygxyYbz52ZO40WUu7EgQ5kDTOeRPnTOd7awWDQcl1gGBXgrkR pAlQ0l0ReO57Q0eglFydLMi5bkwYhfY+TwDPMh3aOP5qBXkm4qIYSsxb8A+i00P72AqFb9Q7 3weG/flxSPApLYQE5qWGSXjOkXJv42NGS6o6gd4RmD6Ap5e8ACo1lSMPfTpGzXlt4aRkBfvb NCfNsQikLZzFYDLbQgKBA33BDeV6vNJ9Cj0SgEGOkYyed4I6AbU0kIy1hHAm1r6+sAnEdIKj cHi3xWH/UPrZW5flM8Kqo14OTDkI9EtlABEBAAHCwF8EGAEIAAkFAkvHyWwCGwwACgkQp6Fr SiUnQ2q03wgAmRFGDeXzc58NX0NrDijUu0zx3Lns/qZ9VrkSWbNZBFjpWKaeL1fdVeE4TDGm I5mRRIsStjQzc2R9b+2VBUhlAqY1nAiBDv0Qnt+9cLiuEICeUwlyl42YdwpmY0ELcy5+u6wz mK/jxrYOpzXKDwLq5k4X+hmGuSNWWAN3gHiJqmJZPkhFPUIozZUCeEc76pS/IUN72NfprZmF Dp6/QDjDFtfS39bHSWXKVZUbqaMPqlj/z6Ugk027/3GUjHHr8WkeL1ezWepYDY7WSoXwfoAL 2UXYsMAr/uUncSKlfjvArhsej0S4zbqim2ZY6S8aRWw94J3bSvJR+Nwbs34GPTD4Pg== Organization: Red Hat, Inc. Message-ID: <252579c4-b425-a7fa-ae14-f0ced12f0830@redhat.com> Date: Fri, 7 Jun 2019 13:15:05 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="74H5XKN6hlWXBqhGOMpIc5g6vFwvFKwHO" 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]); Fri, 07 Jun 2019 18:15:14 +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 2/5] block/dirty-bitmap: Refactor bdrv_can_store_new_bitmap 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: Fam Zheng , Kevin Wolf , Markus Armbruster , Max Reitz 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) --74H5XKN6hlWXBqhGOMpIc5g6vFwvFKwHO Content-Type: multipart/mixed; boundary="8SqgWHEFKmwlf65a1kLx8ZaUMxYaYat5u"; protected-headers="v1" From: Eric Blake To: John Snow , Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" , "qemu-devel@nongnu.org" Cc: Fam Zheng , Max Reitz , Markus Armbruster , Kevin Wolf Message-ID: <252579c4-b425-a7fa-ae14-f0ced12f0830@redhat.com> Subject: Re: [PATCH 2/5] block/dirty-bitmap: Refactor bdrv_can_store_new_bitmap References: <20190606184159.979-1-jsnow@redhat.com> <20190606184159.979-3-jsnow@redhat.com> <70a53585-bdc6-1877-01f5-1b2d1aad8de6@virtuozzo.com> In-Reply-To: --8SqgWHEFKmwlf65a1kLx8ZaUMxYaYat5u Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 6/7/19 1:10 PM, John Snow wrote: >=20 >=20 > On 6/7/19 10:29 AM, Vladimir Sementsov-Ogievskiy wrote: >> 06.06.2019 21:41, John Snow wrote: >>> Instead of bdrv_can_store_new_bitmap, rework this as >>> bdrv_add_persistent_dirty_bitmap. This makes a more obvious symmetry >>> with bdrv_remove_persistent_dirty_bitmap. Most importantly, we are fr= ee >>> to modify the driver state because we know we ARE adding a bitmap >>> instead of simply being asked if we CAN store one. >>> >>> As part of this symmetry, move this function next to >>> bdrv_remove_persistent_bitmap in block/dirty-bitmap.c. >>> >>> To cement this semantic distinction, use a bitmap object instead of t= he >>> (name, granularity) pair as this allows us to set persistence as a >>> condition of the "add" succeeding. >>> >>> Notably, the qcow2 implementation still does not actually store the n= ew >>> bitmap at add time, but merely ensures that it will be able to at sto= re >>> time. >>> >>> +int bdrv_add_persistent_dirty_bitmap(BlockDriverState *bs, >>> + BdrvDirtyBitmap *bitmap, >>> + Error **errp) >> >> strange thing for me: "bitmap" in function name is _not_ the same >> thing as @bitmap argument.. as if it the same, >> function adds "persistent bitmap", but @bitmap is not persistent yet, >> so may be function, don't add persistent bitmap, but marks bitmap pers= istent? >> >> >> Ok, I can think of it like "add persistent dirty bitmap to driver. if = succeed, set >> bitmap.persistent flag" >> >=20 > Yeah, I meant "Add bitmap to file", where the persistence is implied > because it's part of the file. The bitmap is indeed not YET persistent,= > but becomes so as a condition of this call succeeding. >=20 > Do you have a suggestion for a better name? I liked the symmetry with > 'remove' so that there was an obvious "add bitmap" and "remove bitmap".= >=20 > Of course, when you remove, it is indeed persistent, so > "remove_persistent_dirty_bitmap" makes sense there. >=20 Or maybe even merely 'bdrv_add_dirty_bitmap' with doc comments stating that it associates an existing non-persistent bitmap with the bdrv storage and marks it persistent if successful. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --8SqgWHEFKmwlf65a1kLx8ZaUMxYaYat5u-- --74H5XKN6hlWXBqhGOMpIc5g6vFwvFKwHO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlz6qakACgkQp6FrSiUn Q2pgmQgAgK413fwm90xHOcKTPMP+7armwhrqEL/EbntjUO2Dx5nXo7tNTZC40ThU iGfPHIBCxXYS6x74DOCvyi4ngf1F0LHaAHgixh4P6J8dyZYWaWv3NgKjjmUuttZa YIw0RdRlJdfInkDC8JtUwBbmEiXfFtNcLgsYFM/tCZwVzazqBFtN1/j1h/yP7kQH YuKrlyJvFeqyW3V7xKCI+aP3p0YOL8Mlz9wGBqoG7RSNcVZW4QJgavxxgP/KSpJI /V8e6jkc22Yfye7V60I2brbJBo6IAUYlAucnvi1dbbC5PmLTLZ6jQ+RAKcIScUUk pT+P1tXnFpZKleA+dDCHXnE/Anpkxg== =4HMu -----END PGP SIGNATURE----- --74H5XKN6hlWXBqhGOMpIc5g6vFwvFKwHO--