From patchwork Sun May 24 14:51:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alberto Garcia X-Patchwork-Id: 281997 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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 91C7AC433DF for ; Sun, 24 May 2020 14:53:45 +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 54BB120826 for ; Sun, 24 May 2020 14:53:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="YJ2Ik3+i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 54BB120826 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46470 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jcs0W-00043f-Gy for qemu-devel@archiver.kernel.org; Sun, 24 May 2020 10:53:44 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45722) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jcrzZ-0001gN-Fy; Sun, 24 May 2020 10:52:45 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:37779) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jcrzX-0002kE-7X; Sun, 24 May 2020 10:52:45 -0400 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=FkRe2j8xgh8fITQ6IazREs9CCoGHVR/WNb0awBJK/Ko=; b=YJ2Ik3+iNklfA4reOkNzcyqcNApcvUkQ1ONyLM3lNFMBP8WRyfHNh1sPyMbKjnBAdnjs0O2HvrneFuCXhr4D6BP6e+r31OEXcMrHBKF3iaJVS4GPbcWE5UYquEiHXYSXgSAFTsQNAG5axb0VulyeejvXsSbLOS2L0gl2y0G5BsbYkcPxgbE2JwodGLZP6WkNMakal2sI6tv9RAJ1ZnvGOd21UQko2NlTLJo+ZtuN7oiO1UOw7VRna2w9IgsBqPrUcFyEO/oXCJZKEDpy80XPSE1NloIttidSe2NySKXyGpyfqMuFZDpThea89yr10NApJoC+ltlOSSIuQ/SCo3dAaQ==; 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 1jcrz9-0007GH-7d; Sun, 24 May 2020 16:52:19 +0200 Received: from berto by perseus.local with local (Exim 4.92) (envelope-from ) id 1jcryv-0005Ki-C8; Sun, 24 May 2020 16:52:05 +0200 From: Alberto Garcia To: qemu-devel@nongnu.org Subject: [PATCH v6 23/32] qcow2: Add subcluster support to discard_in_l2_slice() Date: Sun, 24 May 2020 16:51:43 +0200 Message-Id: <7f39a9000f6564f2e822a5c232e27b40f72b46f0.1590331741.git.berto@igalia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: References: MIME-Version: 1.0 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 = 2020/05/24 10:52:20 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_PASS=-0.001, URIBL_BLOCKED=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+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Two things need to be taken into account here: 1) With full_discard == 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 == 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 --- block/qcow2-cluster.c | 51 +++++++++++++++++++------------------------ 1 file changed, 22 insertions(+), 29 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 4e59bbd545..5e70b76c21 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1847,11 +1847,16 @@ static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset, assert(nb_clusters <= INT_MAX); for (i = 0; i < nb_clusters; i++) { - uint64_t old_l2_entry; - - old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i); + uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i); + uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); + uint64_t new_l2_entry = old_l2_entry; + uint64_t new_l2_bitmap = old_l2_bitmap; + QCow2ClusterType type = qcow2_get_cluster_type(bs, old_l2_entry); /* + * If full_discard is true, the cluster should not read back as zeroes, + * 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 +1865,28 @@ 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 zeroes, - * 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 = new_l2_bitmap = 0; + } else if (bs->backing || qcow2_cluster_is_allocated(type)) { + if (has_subclusters(s)) { + new_l2_entry = 0; + new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES; + } else { + new_l2_entry = s->qcow_version >= 3 ? QCOW_OFLAG_ZERO : 0; } - break; + } - 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 == new_l2_entry && old_l2_bitmap == new_l2_bitmap) { + continue; } /* First remove L2 entries */ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); - if (!full_discard && s->qcow_version >= 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); }