From patchwork Tue May 5 17:38:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alberto Garcia X-Patchwork-Id: 11529723 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 905301392 for ; Tue, 5 May 2020 17:45:23 +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 6400C206B9 for ; Tue, 5 May 2020 17:45:23 +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="m244Nlvp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6400C206B9 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:57488 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jW1dC-00085K-FB for patchwork-qemu-devel@patchwork.kernel.org; Tue, 05 May 2020 13:45:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44010) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jW1XN-0006IM-Ca; Tue, 05 May 2020 13:39:21 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:38896) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jW1XJ-00089x-B3; Tue, 05 May 2020 13:39:21 -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=cWLIIdo7+a6UMKWUhIqHl4YlcVCyo97eEKdnjWCtExI=; b=m244NlvplRl7oDOaRYrQ9nLGKAGJt0KWIeAfXw3KMJ2P70IYVSYpYTKmm6ORHcdKeASXSdM0gpH3K9pvYRjX7X/H+wtf2L/Jbra9QhxpfQUoCWCA8oyxI0OLZjWIkXNEyr1KmOB6Y8rnEDhYpEysmg13vAGV3C4tvR7CMVqI17nF04x6xXrTqZ3MTnYG+z0P832WQYK9Bmx8d5bY5RCLddrTpiygsu7hmqxImzxKp/DX/RiicXCrTU9SlLMIecGx7mlbvpQ8zV568VdxBedJ12PBAPmk9MPw3MSM1xgnDNHERu8uAUhvWqUoiVHiQihzQKVn1w5TYCkGqvOQ9iISog==; Received: from static.160.43.0.81.ibercom.com ([81.0.43.160] helo=perseus.local) by fanzine.igalia.com with esmtpsa (Cipher TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim) id 1jW1Ws-00025V-Fr; Tue, 05 May 2020 19:38:50 +0200 Received: from berto by perseus.local with local (Exim 4.92) (envelope-from ) id 1jW1Wd-00044F-58; Tue, 05 May 2020 19:38:35 +0200 From: Alberto Garcia To: qemu-devel@nongnu.org Subject: [PATCH v5 22/31] qcow2: Add subcluster support to discard_in_l2_slice() Date: Tue, 5 May 2020 19:38:22 +0200 Message-Id: <28c63d4cf462463dfc275309531f8dc317051fee.1588699789.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 = 2020/05/05 13:38:50 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, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.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 bf32ed0825..2283a308d0 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1804,11 +1804,16 @@ 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 @@ -1817,40 +1822,28 @@ 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); }