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=-11.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 8CE18C433E1 for ; Fri, 21 Aug 2020 11:59:19 +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 53F3020639 for ; Fri, 21 Aug 2020 11:59:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="g7+j9uVo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53F3020639 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]:39238 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k95hW-0001Dq-IA for qemu-devel@archiver.kernel.org; Fri, 21 Aug 2020 07:59:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51340) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k95gz-0000nd-QU for qemu-devel@nongnu.org; Fri, 21 Aug 2020 07:58:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:22692) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1k95gw-0004mR-TN for qemu-devel@nongnu.org; Fri, 21 Aug 2020 07:58:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598011120; h=from:from:reply-to: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=LAeJCt28bCWLCYzYJAbGe5IWKS5xmoN489M8mJ2sTFM=; b=g7+j9uVovJoqhcJS/7QoC5EFlJIWVK7aXXTEc4mBEOy9Ir3P9ZVkQgctwcDzmyHdYNj3zL S0ZOfHC4bQ+W5e098cayX3e8dtUcZeUuPBhwCODLuJYbxhb5Bw+LtkW8PiKXI5PQF9XZ2x IrJxftXfAPZLNaS+L1d/f2FzJ844c+s= 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-520-v6oXekpAO1WSQD7Zof4Qpw-1; Fri, 21 Aug 2020 07:58:39 -0400 X-MC-Unique: v6oXekpAO1WSQD7Zof4Qpw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1E9D110082E0; Fri, 21 Aug 2020 11:58:38 +0000 (UTC) Received: from redhat.com (unknown [10.36.110.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C7CAA7BE99; Fri, 21 Aug 2020 11:58:32 +0000 (UTC) Date: Fri, 21 Aug 2020 12:58:29 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Jiachen Zhang Subject: Re: [PATCH] virtiofsd: add -o allow_directio|no_directio option Message-ID: <20200821115829.GJ348677@redhat.com> References: <20200821034126.8004-1-zhangjiachen.jaycee@bytedance.com> MIME-Version: 1.0 In-Reply-To: <20200821034126.8004-1-zhangjiachen.jaycee@bytedance.com> User-Agent: Mutt/1.14.5 (2020-06-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/21 02:43:55 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_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Yongji Xie , "Dr . David Alan Gilbert" , Stefan Hajnoczi , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Aug 21, 2020 at 11:41:26AM +0800, Jiachen Zhang wrote: > Due to the commit 65da4539803373ec4eec97ffc49ee90083e56efd, the O_DIRECT > open flag of guest applications will be discarded by virtiofsd. While > this behavior makes it consistent with the virtio-9p scheme when guest > applications using direct I/O, we no longer have any chance to bypass > the host page cache. > > Therefore, we add a flag 'allow_directio' to lo_data. If '-o no_directio' > option is added, or none of '-o no_directio' or '-o allow_directio' is > added, the 'allow_directio' will be set to 0, and virtiofsd discards > O_DIRECT as before. If '-o allow_directio' is added to the stariting > command-line, 'allow_directio' will be set to 1, so that the O_DIRECT > flags will be retained and host page cache can be bypassed. > > Signed-off-by: Jiachen Zhang > --- > tools/virtiofsd/helper.c | 4 ++++ > tools/virtiofsd/passthrough_ll.c | 20 ++++++++++++++------ > 2 files changed, 18 insertions(+), 6 deletions(-) > > diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c > index 3105b6c23a..534ff52c64 100644 > --- a/tools/virtiofsd/helper.c > +++ b/tools/virtiofsd/helper.c > @@ -180,6 +180,10 @@ void fuse_cmdline_help(void) > " (0 leaves rlimit unchanged)\n" > " default: min(1000000, fs.file-max - 16384)\n" > " if the current rlimit is lower\n" > + " -o allow_directio|no_directio\n" > + " retain/discard O_DIRECT flags passed down\n" > + " to virtiofsd from guest applications.\n" > + " default: no_directio\n" > ); The standard naming convention from existing options is to use $OPTNAME and no_$OPTNAME. IOW, don't use the "allow_" prefix. The options should be just "directio" and "no_directio" Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|