From nobody Mon Feb 9 03:13:12 2026 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=1563187589; cv=none; d=zoho.com; s=zohoarc; b=FFL9PwUGKJ5ndN5OR5A2tkPHLn9plALmdJ7gFWFV3yTXHCPTVJKIxl51mUkvJcebw09cNKXgCMjorEKV3WGgpMNPmgfy2MXh4Bj1eQlVr9dCCs3U0gkLwLQIG16zILPmxl11cHFaCOhQsnsbYUow/otroTEUz2DPl+92xJenM2s= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1563187589; 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=KBFa1koU0a5UoNLmpwM74YkXLyqhZUnZT7yddhAR3JU=; b=FCqTN+U60NL8uz/rg0/VfEqKL3CXlEcXwwswJRmJtHp3ji36kvCWVYRt3DZD1V7aNujHMxh8PFzOHoBRZ/tTHu1mlaiI2YqyIe0l1dqaf9oG4lhxASO7xZmRl7+maFVsZ74ThKfbgfSoDSmme0tQfIa6DGvI8HP7nigKb26JUTY= 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 1563187589413663.2799408902812; Mon, 15 Jul 2019 03:46:29 -0700 (PDT) Received: from localhost ([::1]:36838 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hmyV2-0006Fk-4m for importer@patchew.org; Mon, 15 Jul 2019 06:46:28 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39329) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hmyTv-0002AU-CF for qemu-devel@nongnu.org; Mon, 15 Jul 2019 06:45:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hmyTu-0001fU-9P for qemu-devel@nongnu.org; Mon, 15 Jul 2019 06:45:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34530) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hmyTr-0001do-Ma; Mon, 15 Jul 2019 06:45:15 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0B5D6307D847; Mon, 15 Jul 2019 10:45:15 +0000 (UTC) Received: from localhost (unknown [10.40.205.59]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5F8014505; Mon, 15 Jul 2019 10:45:14 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Mon, 15 Jul 2019 12:45:05 +0200 Message-Id: <20190715104508.7568-2-mreitz@redhat.com> In-Reply-To: <20190715104508.7568-1-mreitz@redhat.com> References: <20190715104508.7568-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 15 Jul 2019 10:45:15 +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 for-4.1? 1/4] qcow2: Fix .bdrv_has_zero_init() 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 , Jeff Cody , Stefan Weil , qemu-devel@nongnu.org, Max Reitz , Stefano Garzarella Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" If a qcow2 file is preallocated, it can no longer guarantee that it initially appears as filled with zeroes. So implement .bdrv_has_zero_init() by checking whether the file is preallocated; if so, forward the call to the underlying storage node, except for when it is encrypted: Encrypted preallocated images always return effectively random data, so .bdrv_has_zero_init() must always return 0 for them. Reported-by: Stefano Garzarella Signed-off-by: Max Reitz --- block/qcow2.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 89 insertions(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index 039bdc2f7e..730fd53890 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -4631,6 +4631,94 @@ static ImageInfoSpecific *qcow2_get_specific_info(Bl= ockDriverState *bs, return spec_info; } =20 +/* + * Return 1 if the file only contains zero and unallocated clusters. + * Return 0 if it contains compressed or normal clusters. + * Return -errno on error. + */ +static int qcow2_is_zero(BlockDriverState *bs) +{ + BDRVQcow2State *s =3D bs->opaque; + int l1_i; + int ret; + + if (bs->backing) { + return 0; + } + + for (l1_i =3D 0; l1_i < s->l1_size; l1_i++) { + uint64_t l2_offset =3D s->l1_table[l1_i] & L1E_OFFSET_MASK; + int slice_start_i; + + if (!l2_offset) { + continue; + } + + for (slice_start_i =3D 0; slice_start_i < s->l2_size; + slice_start_i +=3D s->l2_slice_size) + { + uint64_t *l2_slice; + int l2_slice_i; + + ret =3D qcow2_cache_get(bs, s->l2_table_cache, + l2_offset + slice_start_i * sizeof(uint6= 4_t), + (void **)&l2_slice); + if (ret < 0) { + return ret; + } + + for (l2_slice_i =3D 0; l2_slice_i < s->l2_slice_size; l2_slice= _i++) { + uint64_t l2_entry =3D be64_to_cpu(l2_slice[l2_slice_i]); + + switch (qcow2_get_cluster_type(bs, l2_entry)) { + case QCOW2_CLUSTER_UNALLOCATED: + case QCOW2_CLUSTER_ZERO_PLAIN: + case QCOW2_CLUSTER_ZERO_ALLOC: + break; + + case QCOW2_CLUSTER_NORMAL: + case QCOW2_CLUSTER_COMPRESSED: + qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice); + return 0; + + default: + abort(); + } + } + + qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice); + } + } + + return 1; +} + +static int qcow2_has_zero_init(BlockDriverState *bs) +{ + BDRVQcow2State *s =3D bs->opaque; + int ret; + + if (qemu_in_coroutine()) { + qemu_co_mutex_lock(&s->lock); + } + /* Check preallocation status */ + ret =3D qcow2_is_zero(bs); + if (qemu_in_coroutine()) { + qemu_co_mutex_unlock(&s->lock); + } + if (ret < 0) { + return 0; + } + + if (ret =3D=3D 1) { + return 1; + } else if (bs->encrypted) { + return 0; + } else { + return bdrv_has_zero_init(s->data_file->bs); + } +} + static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos) { @@ -5186,7 +5274,7 @@ BlockDriver bdrv_qcow2 =3D { .bdrv_child_perm =3D bdrv_format_default_perms, .bdrv_co_create_opts =3D qcow2_co_create_opts, .bdrv_co_create =3D qcow2_co_create, - .bdrv_has_zero_init =3D bdrv_has_zero_init_1, + .bdrv_has_zero_init =3D qcow2_has_zero_init, .bdrv_co_block_status =3D qcow2_co_block_status, =20 .bdrv_co_preadv =3D qcow2_co_preadv, --=20 2.21.0