From nobody Sun Feb 8 22:17:46 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=1591802233; cv=none; d=zohomail.com; s=zohoarc; b=G+en/87JhhndHZKXM0Pr8vugvUgeHJOslmrARJOIni+IwWuuU8AciG7GnViPscSodib1N6ZQvwGA/5OaVPdfDf6FDrYqPyo/aEuKSUTUW/xLzcMP9rha0TNs431LHBgQoqbAvGLKgdNwza9jbt7/5OFqlkjSlxRESqVYrHtoZu8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1591802233; 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=wwP+F61UHuBD2MYWJK+ZYjI142FX+Mf725oBfkWGky0=; b=TEoNQpRwCaJ8ECAO0aYeqzEJIoe/wNqIOKxq1BF4KkHPpSuFfnW+La3G0qUgy2YARU4zqUMY/gGvf+fVEX/8m0/V7VTR2sFTNiMZGf3Bar1zRiwkEOFvTqYmx0UW0N80cH6l8CYffU6+PvzuI9fHNxhcz+qyckL9dVnn4vsLV2A= 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 1591802233589739.4729606287277; Wed, 10 Jun 2020 08:17:13 -0700 (PDT) Received: from localhost ([::1]:32998 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jj2TY-0004MA-6M for importer@patchew.org; Wed, 10 Jun 2020 11:17:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36142) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jj2Gv-0002gd-IN; Wed, 10 Jun 2020 11:04:09 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:58130) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jj2Gr-0006wD-FP; Wed, 10 Jun 2020 11:04:08 -0400 Received: from [81.0.38.199] (helo=perseus.local) by fanzine.igalia.com with esmtpsa (Cipher TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim) id 1jj2GR-0007h7-Jp; Wed, 10 Jun 2020 17:03:39 +0200 Received: from berto by perseus.local with local (Exim 4.92) (envelope-from ) id 1jj2GC-0007NT-BL; Wed, 10 Jun 2020 17:03:24 +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=wwP+F61UHuBD2MYWJK+ZYjI142FX+Mf725oBfkWGky0=; b=Gr5+q/YR5Qtn1aQNXbzPMc0bF3iA+k7xsybnQlVTWyPRyKfl8SY1hPIq4kKiNGyDvSuS3ux429tlYtOKYjoQjQsCACdiyZ1dBr6PzSeRcRsQ/92Ng8BNvw65YJgK/xP8kP2BQJ69Yvuwsp5WyVmJXsqma4iopB82WBm95fS9xixvm6l2FvbvZ5dVDTyqN7Xh3OYZdrCiZNViWg2bfLIBndauZMi8chFCi7PUQC5RZju4FnYB1a+rv8ohOgLUVm0A72jiyJzP96/f9cqulzwy+LHedRcxgryNgeDJtA2POUQxurESpvUVtEHBgEllbkjl0Sq2iC9YdqN+/X2VuB/uug==; From: Alberto Garcia To: qemu-devel@nongnu.org Subject: [PATCH v8 23/34] qcow2: Add subcluster support to discard_in_l2_slice() Date: Wed, 10 Jun 2020 17:03:01 +0200 Message-Id: <402a16641f750c1069e0926c454f1da7b2eca10b.1591801197.git.berto@igalia.com> 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 = 2020/06/10 11:03:39 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=_AUTOLEARN 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, Derek Su , 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" Two things need to be taken into account here: 1) With full_discard =3D=3D true the L2 entry must be cleared completely. This also includes the L2 bitmap if the image has extended L2 entries. 2) With full_discard =3D=3D false we have to make the discarded cluster read back as zeroes. With normal L2 entries this is done with the QCOW_OFLAG_ZERO bit, whereas with extended L2 entries this is done with the individual 'all zeroes' bits for each subcluster. Note however that QCOW_OFLAG_ZERO is not supported in v2 qcow2 images so, if there is a backing file, discard cannot guarantee that the image will read back as zeroes. If this is important for the caller it should forbid it as qcow2_co_pdiscard() does (see 80f5c01183 for more details). Signed-off-by: Alberto Garcia Reviewed-by: Eric Blake --- block/qcow2-cluster.c | 52 +++++++++++++++++++------------------------ 1 file changed, 23 insertions(+), 29 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 4e59bbd545..edfc8ea91c 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1847,11 +1847,17 @@ static int discard_in_l2_slice(BlockDriverState *bs= , uint64_t offset, assert(nb_clusters <=3D INT_MAX); =20 for (i =3D 0; i < nb_clusters; i++) { - uint64_t old_l2_entry; - - old_l2_entry =3D get_l2_entry(s, l2_slice, l2_index + i); + uint64_t old_l2_entry =3D get_l2_entry(s, l2_slice, l2_index + i); + uint64_t old_l2_bitmap =3D get_l2_bitmap(s, l2_slice, l2_index + i= ); + uint64_t new_l2_entry =3D old_l2_entry; + uint64_t new_l2_bitmap =3D old_l2_bitmap; + QCow2ClusterType cluster_type =3D + qcow2_get_cluster_type(bs, old_l2_entry); =20 /* + * If full_discard is true, the cluster should not read back as ze= roes, + * but rather fall through to the backing file. + * * If full_discard is false, make sure that a discarded area reads= back * as zeroes for v3 images (we cannot do it for v2 without actually * writing a zero-filled buffer). We can skip the operation if the @@ -1860,40 +1866,28 @@ static int discard_in_l2_slice(BlockDriverState *bs= , uint64_t offset, * * TODO We might want to use bdrv_block_status(bs) here, but we're * holding s->lock, so that doesn't work today. - * - * If full_discard is true, the sector should not read back as zer= oes, - * but rather fall through to the backing file. */ - switch (qcow2_get_cluster_type(bs, old_l2_entry)) { - case QCOW2_CLUSTER_UNALLOCATED: - if (full_discard || !bs->backing) { - continue; + if (full_discard) { + new_l2_entry =3D new_l2_bitmap =3D 0; + } else if (bs->backing || qcow2_cluster_is_allocated(cluster_type)= ) { + if (has_subclusters(s)) { + new_l2_entry =3D 0; + new_l2_bitmap =3D QCOW_L2_BITMAP_ALL_ZEROES; + } else { + new_l2_entry =3D s->qcow_version >=3D 3 ? QCOW_OFLAG_ZERO = : 0; } - break; + } =20 - case QCOW2_CLUSTER_ZERO_PLAIN: - if (!full_discard) { - continue; - } - break; - - case QCOW2_CLUSTER_ZERO_ALLOC: - case QCOW2_CLUSTER_NORMAL: - case QCOW2_CLUSTER_COMPRESSED: - break; - - default: - abort(); + if (old_l2_entry =3D=3D new_l2_entry && old_l2_bitmap =3D=3D new_l= 2_bitmap) { + continue; } =20 /* First remove L2 entries */ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); - if (!full_discard && s->qcow_version >=3D 3) { - set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO); - } else { - set_l2_entry(s, l2_slice, l2_index + i, 0); + set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry); + if (has_subclusters(s)) { + set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap); } - /* Then decrease the refcount */ qcow2_free_any_clusters(bs, old_l2_entry, 1, type); } --=20 2.20.1