From nobody Thu Dec 18 13:19:11 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1566231802; cv=none; d=zoho.com; s=zohoarc; b=kMtWGrjM4YVFnkzd9o0TKlo3FNiPut4C2qZpJ3naCU4pkE/ks0zaWfNlOOeaJy8T7Z4nueYkNh75LnlZht+Nlpvay8W6ubX57ixcZGX5ca+YPcdK3w4Nt6j/YiyW8pgaWapurC+On9zRYv78wjA+DiuxPT0rUi6iNXf6iA+kSz8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1566231802; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=M4/c9mocEvz8PIebdTGBR0GZG9jQIdLcO5z/qVlFRBM=; b=RdIcNaYPlUlgoc0yUW8jolG+pbYKy9nEMHJ5oVkF5qZz67egyH6RJp/BBnhvfcsT/87SvWbPiZjSxaH61gvqQXM85ZH/9Sb2dNuLnG1G9h7VGnPxQ5HEs+nOIZJLJ7Zu4JdG1TvxSggK0+nwhz9lBDvjMudkj6idmJ6Gsmta6Fs= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 156623180206280.18337791884812; Mon, 19 Aug 2019 09:23:22 -0700 (PDT) Received: from localhost ([::1]:55252 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzkRE-00005X-Kb for importer@patchew.org; Mon, 19 Aug 2019 12:23:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35307) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzkLn-0002ox-4p for qemu-devel@nongnu.org; Mon, 19 Aug 2019 12:17:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hzkLl-0006HO-Qr for qemu-devel@nongnu.org; Mon, 19 Aug 2019 12:17:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58724) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hzkLj-0006Fn-62; Mon, 19 Aug 2019 12:17:39 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7D386106E96E; Mon, 19 Aug 2019 16:17:38 +0000 (UTC) Received: from localhost (ovpn-204-64.brq.redhat.com [10.40.204.64]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1116F8CC0E; Mon, 19 Aug 2019 16:17:37 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Mon, 19 Aug 2019 18:17:10 +0200 Message-Id: <20190819161723.7746-5-mreitz@redhat.com> In-Reply-To: <20190819161723.7746-1-mreitz@redhat.com> References: <20190819161723.7746-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.66]); Mon, 19 Aug 2019 16:17:38 +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] [PULL 04/17] 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 , Peter Maydell , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" 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 Message-id: 20190724171239.8764-4-mreitz@redhat.com Reviewed-by: Maxim Levitsky Reviewed-by: Stefano Garzarella 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 89e40318cf..124ad40809 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -443,6 +443,7 @@ int bdrv_pdiscard(BdrvChild *child, int64_t offset, int= 64_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 8fa011654a..ceec8c2f56 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -419,9 +419,16 @@ 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 e= vent * 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 3e698e9cab..874a29a983 100644 --- a/block.c +++ b/block.c @@ -5078,6 +5078,27 @@ 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 sorry= */ + 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