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 X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 8E2D0C433DF for ; Fri, 10 Jul 2020 14:40:21 +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 57E6B20748 for ; Fri, 10 Jul 2020 14:40:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="g9rKjZTw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 57E6B20748 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51394 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jtuCK-0003mv-Fo for qemu-devel@archiver.kernel.org; Fri, 10 Jul 2020 10:40:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44858) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jtuBV-0003HE-WD for qemu-devel@nongnu.org; Fri, 10 Jul 2020 10:39:30 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:57599 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jtuBT-0006Gr-5R for qemu-devel@nongnu.org; Fri, 10 Jul 2020 10:39:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594391966; 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=HFFqjBQFxtOsgciogsWvXUYbUHUNVe2+Ge4YGH6V9Fg=; b=g9rKjZTw/GvIYhTF36asOtdiUG15ePyKGrLMD5tLRaRG6mUCMe2gNGG1EXWVmzd0rPLKgo k5MIN6tZv/Jaig38fYQhH0VjBS81YnG0h2qKytqCtkkOQ3W+XBO3A8JZBiQLeSDoW/q4PZ xYSdi9iIbBfgg4Cax3tHYOSmbKLhTgA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-432-kZBQii_8NA23yxICkFzKww-1; Fri, 10 Jul 2020 10:39:24 -0400 X-MC-Unique: kZBQii_8NA23yxICkFzKww-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 8A3AA80BCA7; Fri, 10 Jul 2020 14:39:23 +0000 (UTC) Received: from [10.3.112.178] (ovpn-112-178.phx2.redhat.com [10.3.112.178]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 36EFC1CA; Fri, 10 Jul 2020 14:39:23 +0000 (UTC) Subject: Re: [PATCH for-5.1 2/2] file-posix: Allow byte-aligned O_DIRECT with NFS To: Kevin Wolf , qemu-block@nongnu.org References: <20200710142149.40962-1-kwolf@redhat.com> <20200710142149.40962-3-kwolf@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <83827826-87c8-8227-2fbc-22b7ff2fb6e6@redhat.com> Date: Fri, 10 Jul 2020 09:39:22 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200710142149.40962-3-kwolf@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/10 04:36:30 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no 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: qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 7/10/20 9:21 AM, Kevin Wolf wrote: > Since commit a6b257a08e3 ('file-posix: Handle undetectable alignment'), > we assume that if we open a file with O_DIRECT and alignment probing > returns 1, we just couldn't find out the real alignment requirement > because some filesystems make the requirement only for allocated blocks. > In this case, a safe default of 4k is used. > > This is too strict NFS, which does actually allow byte-aligned requests strict for > even with O_DIRECT. Because we can't distinguish both cases with generic > code, let's just look at the file system magic and disable > s->needs_alignment for NFS. This way, O_DIRECT can still be used on NFS > for images that are not aligned to 4k. > > Signed-off-by: Kevin Wolf > --- > block/file-posix.c | 26 +++++++++++++++++++++++++- > 1 file changed, 25 insertions(+), 1 deletion(-) > Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org