From mboxrd@z Thu Jan 1 00:00:00 1970 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 EE822C43217 for ; Fri, 11 Nov 2022 11:09:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1otRu0-0003J2-JD; Fri, 11 Nov 2022 06:08:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1otRty-0003IZ-FQ for qemu-devel@nongnu.org; Fri, 11 Nov 2022 06:08:50 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1otRtw-0006TP-Gr for qemu-devel@nongnu.org; Fri, 11 Nov 2022 06:08:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668164921; 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: in-reply-to:in-reply-to:references:references; bh=00NeJOjCGNjHTm3dxLS2lrs5R9blDdYuGal63PE7Ckk=; b=Kvog028NP7f+XNJ4KU1zTUJ0BCqcSMEN91PUgix8ABKAC+MAQQaxXUnK8e9DJlClTU3FVu yskqO1DXTYnLbB5zdmpfc9AYOOSCZCOLj3+mpYgC6uwk9i97mU1Yh581W5DqSC5lcEEXwV xHnnK6dAewVsEyxJrB6QjHC4+dofBrk= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-141-LN0pBn4pOsaD4tJsXR7-nQ-1; Fri, 11 Nov 2022 06:08:40 -0500 X-MC-Unique: LN0pBn4pOsaD4tJsXR7-nQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DF3F73C0F446; Fri, 11 Nov 2022 11:08:39 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.152]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 06D0F202322E; Fri, 11 Nov 2022 11:08:38 +0000 (UTC) Date: Fri, 11 Nov 2022 12:08:36 +0100 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Hanna Reitz , nsoffer@redhat.com, qemu-block@nongnu.org Subject: Re: [PATCH v2 1/2] file-posix: fix Linux alignment probing when EIO is returned Message-ID: References: <20221103183609.363027-1-stefanha@redhat.com> <20221103183609.363027-2-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221103183609.363027-2-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 03.11.2022 um 19:36 hat Stefan Hajnoczi geschrieben: > Linux v6.0 dm-crypt returns errno EIO from unaligned O_DIRECT pread(2) > calls. Alignment probing fails on dm-crypt devices because the code > expects EINVAL. This is a kernel regression that is expected to be fixed > upstream: > https://lore.kernel.org/linux-block/20221103193837.3b5b4bac@xps.demsh.org/T/#t > > Treating any errno as an "unaligned" indicator would be easy, but breaks > commit 22d182e82b4b ("block/raw-posix: fix launching with failed > disks"). Offline disks return EIO for correctly aligned requests and > EINVAL for unaligned requests. > > It's possible to make both v6.0 dm-crypt and offline disks work: look > for the transition from EINVAL to EIO instead of for a single EINVAL > value. > > Buglink: https://gitlab.com/qemu-project/qemu/-/issues/1290 > Fixes: 22d182e82b4b ("block/raw-posix: fix launching with failed disks") > Signed-off-by: Stefan Hajnoczi I haven't tested it myself, but from the comments in the bug tracker and on the mailing this, I don't think this can actually distinguish the two cases: AIUI, even with the buggy dm-crypt, you get a transition from EINVAL to EIO because everything < 512 (such as our first probed value 1) will still return EINVAL. So even with this patch, I think we would still probe the incorrect 512 bytes when the dm-crypt bug is present. Kevin