From patchwork Mon Jan 17 16:26:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12715581 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B3148C433EF for ; Mon, 17 Jan 2022 16:29:32 +0000 (UTC) Received: from localhost ([::1]:34302 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n9Ust-0003N2-NI for qemu-devel@archiver.kernel.org; Mon, 17 Jan 2022 11:29:31 -0500 Received: from eggs.gnu.org ([209.51.188.92]:32816) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n9Uqa-0000ao-Q3 for qemu-devel@nongnu.org; Mon, 17 Jan 2022 11:27:08 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:49472) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n9UqW-00012O-Dd for qemu-devel@nongnu.org; Mon, 17 Jan 2022 11:27:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642436823; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RanLABclwS1rxfLdARyAScIv31MGF+bW4scJmZngNJQ=; b=I5aaw7RuDceY3sZpONNOpeuE9a3quNscj2d/ZjNZRuLq04RGLs/7KLTw68R2RHgrvKwHup B2N3ERHrFWki+dmuQaSptl5u8/wCmi2ffqM5vLsrpLoXYcAEVSpVfDWJhq2ZWaZ7zLW6CI fPTdjMmsXsMQOMDvK3li538G+j6Kgc8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-67-zWB-XJ_jMOaU7y7vjtsfQw-1; Mon, 17 Jan 2022 11:26:55 -0500 X-MC-Unique: zWB-XJ_jMOaU7y7vjtsfQw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1B3D31083F62; Mon, 17 Jan 2022 16:26:54 +0000 (UTC) Received: from localhost (unknown [10.39.193.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AFF105B950; Mon, 17 Jan 2022 16:26:53 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH 1/2] block/io: Update BSC only if want_zero is true Date: Mon, 17 Jan 2022 17:26:48 +0100 Message-Id: <20220117162649.193501-2-hreitz@redhat.com> In-Reply-To: <20220117162649.193501-1-hreitz@redhat.com> References: <20220117162649.193501-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Nir Soffer , Hanna Reitz , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" We update the block-status cache whenever we get new information from a bdrv_co_block_status() call to the block driver. However, if we have passed want_zero=false to that call, it may flag areas containing zeroes as data, and so we would update the block-status cache with wrong information. Therefore, we should not update the cache with want_zero=false. Reported-by: Nir Soffer Fixes: 0bc329fbb009f8601cec23bf2bc48ead0c5a5fa2 ("block: block-status cache for data regions") Signed-off-by: Hanna Reitz Reviewed-by: Nir Soffer --- block/io.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/block/io.c b/block/io.c index bb0a254def..4e4cb556c5 100644 --- a/block/io.c +++ b/block/io.c @@ -2497,8 +2497,12 @@ static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs, * non-protocol nodes, and then it is never used. However, filling * the cache requires an RCU update, so double check here to avoid * such an update if possible. + * + * Check want_zero, because we only want to update the cache when we + * have accurate information about what is zero and what is data. */ - if (ret == (BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID) && + if (want_zero && + ret == (BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID) && QLIST_EMPTY(&bs->children)) { /*