From nobody Mon Feb 9 09:01:33 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org ARC-Seal: i=1; a=rsa-sha256; t=1600698857; cv=none; d=zohomail.com; s=zohoarc; b=W1zJfYh2fxCEUzjnpJCm0rVWt+tYjMftNYZcUMOIhpYXpsuhOkXZZpb7ZRZ56xg1XZV9iW+3vAqrugM4WlHzsLGLmdZf+Hl99T0srYddeLL+p19x7Uy2NoaMnUd3EJ8LlcyMhsVkA2hRYdVz5SsyGyyZ9G8wj3+cS6FS6doxqi4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1600698857; 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; bh=Tw8Cc9SW+/2F9odwf3t7puTe414oOegZOiua3UDi2nU=; b=gYTqPr48PlcRRTq22I+01aQZtaU6dKM3G5lM4mX+bzLkrqCPqZRApwcwM8tOi5B3Kh1s+DhVo8zRw3d2OFnRr9mLhBNbixamfRKpOdpdeHyNcXfulS32L7MKnT+RSqnXEon1ezs1jeZmiW7VhcLgJMDwwvt+MISbWgzRLn+grcY= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1600698856789385.49566057605114; Mon, 21 Sep 2020 07:34:16 -0700 (PDT) Received: from localhost ([::1]:37394 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kKMtT-0005En-Ee for importer@patchew.org; Mon, 21 Sep 2020 10:34:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47788) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kKMqZ-0003g3-I6; Mon, 21 Sep 2020 10:31:15 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:47069) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kKMqU-000485-Qd; Mon, 21 Sep 2020 10:31:14 -0400 Received: from [81.0.34.134] (helo=perseus.local) by fanzine.igalia.com with esmtpsa (Cipher TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim) id 1kKMqQ-0000Wf-9Z; Mon, 21 Sep 2020 16:31:06 +0200 Received: from berto by perseus.local with local (Exim 4.92) (envelope-from ) id 1kKMqD-0005yV-3j; Mon, 21 Sep 2020 16:30:53 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From; bh=Tw8Cc9SW+/2F9odwf3t7puTe414oOegZOiua3UDi2nU=; b=L7gh9t7P9WP/9i9d5cnBCEP+oOtHRiXeSr8cdS31cHx8iM6aFGk1JfrogdX6tp9R6rTZAJD0RZ3NMpbwPpuX9QGE7B2mcTXN1YAPXCV1G61tnl4MkP4DicK8/J1wurrROIIPrkL3MJ4YrqfYhLxP6Ge/rCdqYqaZspBYfuB6HPTyCJFP1pMYr4ebIlpzFt6fh4zqlni/4CNCrpy7oskCIntkKyXQ+ZlGlOabp/NWrGtpOybZBnw1E9MRKuRRlOKbRyt5gpJ/GmGGvBwBXuQbghaYFyjtdn3Ume97f9A+j2AIr6/i9ZxSSPFA6G4GlJWZyrxfX/OHOQMj6wWJpzx3Tw==; From: Alberto Garcia To: qemu-devel@nongnu.org Subject: [PATCH v4 1/2] qcow2: Report BDRV_BLOCK_ZERO more accurately in bdrv_co_block_status() Date: Mon, 21 Sep 2020 16:30:49 +0200 Message-Id: X-Mailer: git-send-email 2.20.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.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; Received-SPF: pass client-ip=178.60.130.6; envelope-from=berto@igalia.com; helo=fanzine.igalia.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/21 10:31:07 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x (no timestamps) [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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 , Vladimir Sementsov-Ogievskiy , Alberto Garcia , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" If a BlockDriverState supports backing files but has none then any unallocated area reads back as zeroes. bdrv_co_block_status() is only reporting this is if want_zero is true, but this is an inexpensive test and there is no reason not to do it in all cases. Suggested-by: Vladimir Sementsov-Ogievskiy Signed-off-by: Alberto Garcia Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/io.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/io.c b/block/io.c index a2389bb38c..ef1ea806e8 100644 --- a/block/io.c +++ b/block/io.c @@ -2391,17 +2391,17 @@ static int coroutine_fn bdrv_co_block_status(BlockD= riverState *bs, =20 if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) { ret |=3D BDRV_BLOCK_ALLOCATED; - } else if (want_zero && bs->drv->supports_backing) { + } else if (bs->drv->supports_backing) { BlockDriverState *cow_bs =3D bdrv_cow_bs(bs); =20 - if (cow_bs) { + if (!cow_bs) { + ret |=3D BDRV_BLOCK_ZERO; + } else if (want_zero) { int64_t size2 =3D bdrv_getlength(cow_bs); =20 if (size2 >=3D 0 && offset >=3D size2) { ret |=3D BDRV_BLOCK_ZERO; } - } else { - ret |=3D BDRV_BLOCK_ZERO; } } =20 --=20 2.20.1