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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 1D8FDC76186 for ; Wed, 24 Jul 2019 17:13:31 +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 E3D0521911 for ; Wed, 24 Jul 2019 17:13:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E3D0521911 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]:53598 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqKpV-0005Xp-GI for qemu-devel@archiver.kernel.org; Wed, 24 Jul 2019 13:13:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49454) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqKp0-0003lQ-HM for qemu-devel@nongnu.org; Wed, 24 Jul 2019 13:12:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hqKoy-0004sT-Cf for qemu-devel@nongnu.org; Wed, 24 Jul 2019 13:12:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56110) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hqKou-0004es-O9; Wed, 24 Jul 2019 13:12:52 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 10A88307D85B; Wed, 24 Jul 2019 17:12:52 +0000 (UTC) Received: from localhost (ovpn-204-115.brq.redhat.com [10.40.204.115]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9AFF91001DDE; Wed, 24 Jul 2019 17:12:51 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Wed, 24 Jul 2019 19:12:31 +0200 Message-Id: <20190724171239.8764-4-mreitz@redhat.com> In-Reply-To: <20190724171239.8764-1-mreitz@redhat.com> References: <20190724171239.8764-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Wed, 24 Jul 2019 17:12:52 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 03/11] block: Add bdrv_has_zero_init_truncate() 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 , Stefano Garzarella , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" No .bdrv_has_zero_init() implementation returns 1 if growing the file would add non-zero areas (at least with PREALLOC_MODE_OFF), so using it in lieu of this new function was always safe. But on the other hand, it is possible that growing an image that is not zero-initialized would still add a zero-initialized area, like when using nonpreallocating truncation on a preallocated image. For callers that care only about truncation, not about creation with potential preallocation, this new function is useful. Alternatively, we could have added a PreallocMode parameter to bdrv_has_zero_init(). But the only user would have been qemu-img convert, which does not have a plain PreallocMode value right now -- it would have to parse the creation option to obtain it. Therefore, the simpler solution is to let bdrv_has_zero_init() inquire the preallocation status and add the new bdrv_has_zero_init_truncate() that presupposes PREALLOC_MODE_OFF. Signed-off-by: Max Reitz --- include/block/block.h | 1 + include/block/block_int.h | 7 +++++++ block.c | 21 +++++++++++++++++++++ 3 files changed, 29 insertions(+) diff --git a/include/block/block.h b/include/block/block.h index 50a07c1c33..5321d8afdf 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -438,6 +438,7 @@ int bdrv_pdiscard(BdrvChild *child, int64_t offset, i= nt64_t bytes); int bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes); int bdrv_has_zero_init_1(BlockDriverState *bs); int bdrv_has_zero_init(BlockDriverState *bs); +int bdrv_has_zero_init_truncate(BlockDriverState *bs); bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs); bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs); int bdrv_block_status(BlockDriverState *bs, int64_t offset, diff --git a/include/block/block_int.h b/include/block/block_int.h index 6a0b1b5008..d7fc6b296b 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -420,9 +420,16 @@ struct BlockDriver { /* * Returns 1 if newly created images are guaranteed to contain only * zeros, 0 otherwise. + * Must return 0 if .bdrv_has_zero_init_truncate() returns 0. */ int (*bdrv_has_zero_init)(BlockDriverState *bs); =20 + /* + * Returns 1 if new areas added by growing the image with + * PREALLOC_MODE_OFF contain only zeros, 0 otherwise. + */ + int (*bdrv_has_zero_init_truncate)(BlockDriverState *bs); + /* Remove fd handlers, timers, and other event loop callbacks so the= event * loop is no longer in use. Called with no in-flight requests and = in * depth-first traversal order with parents before child nodes. diff --git a/block.c b/block.c index cbd8da5f3b..81ae44dcf3 100644 --- a/block.c +++ b/block.c @@ -5066,6 +5066,27 @@ int bdrv_has_zero_init(BlockDriverState *bs) return 0; } =20 +int bdrv_has_zero_init_truncate(BlockDriverState *bs) +{ + if (!bs->drv) { + return 0; + } + + if (bs->backing) { + /* Depends on the backing image length, but better safe than sor= ry */ + return 0; + } + if (bs->drv->bdrv_has_zero_init_truncate) { + return bs->drv->bdrv_has_zero_init_truncate(bs); + } + if (bs->file && bs->drv->is_filter) { + return bdrv_has_zero_init_truncate(bs->file->bs); + } + + /* safe default */ + return 0; +} + bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs) { BlockDriverInfo bdi; --=20 2.21.0