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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 87286C32753 for ; Fri, 2 Aug 2019 08:16:59 +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 640DF20880 for ; Fri, 2 Aug 2019 08:16:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 640DF20880 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60892 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1htSkE-0000jg-ET for qemu-devel@archiver.kernel.org; Fri, 02 Aug 2019 04:16:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39199) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1htSjp-0000Kj-Qc for qemu-devel@nongnu.org; Fri, 02 Aug 2019 04:16:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1htSjo-000112-Ak for qemu-devel@nongnu.org; Fri, 02 Aug 2019 04:16:33 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:2183 helo=huawei.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1htSjo-0000vT-04 for qemu-devel@nongnu.org; Fri, 02 Aug 2019 04:16:32 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id A029CE61FE73E52B6563; Fri, 2 Aug 2019 16:16:21 +0800 (CST) Received: from [10.177.253.249] (10.177.253.249) by smtp.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.439.0; Fri, 2 Aug 2019 16:16:20 +0800 To: "Dr. David Alan Gilbert" , Eric Blake References: <5D3F8F04.3030404@huawei.com> <4ec43f2f-1d72-5fe1-3b93-2c75ee6f87b4@redhat.com> <20190801142016.GI2773@work-vm> <20190801142637.GJ2773@work-vm> From: piaojun Message-ID: <5D43F143.6060901@huawei.com> Date: Fri, 2 Aug 2019 16:16:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20190801142637.GJ2773@work-vm> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.253.249] X-CFilter-Loop: Reflected X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 45.249.212.190 Subject: Re: [Qemu-devel] [Virtio-fs] [PATCH] virtiofsd: fix compile error if 'F_OFD_GETLK' not defined 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: virtio-fs@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Dave and Eric, On 2019/8/1 22:26, Dr. David Alan Gilbert wrote: > * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote: >> * Eric Blake (eblake@redhat.com) wrote: >>> On 7/29/19 7:27 PM, piaojun wrote: >>>> Use F_GETLK for fcntl when F_OFD_GETLK not defined. >>> >>> Which system are you hitting this problem on? >>> >>> The problem with F_GETLK is that it is NOT as safe as F_OFD_GETLK. >>> >>> We already have fcntl_op_getlk and qemu_probe_lock_ops() in util/osdep.c >>> to not only determine which form to use, but also to emit a warning to >>> the end user if we had to fall back to the unsafe F_GETLK. Why is your >>> code not reusing that logic? >>> >>>> >>>> Signed-off-by: Jun Piao >>>> --- >>>> contrib/virtiofsd/passthrough_ll.c | 9 +++++++++ >>>> 1 file changed, 9 insertions(+) >>>> >>>> diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthrough_ll.c >>>> index 9ae1381..757785b 100644 >>>> --- a/contrib/virtiofsd/passthrough_ll.c >>>> +++ b/contrib/virtiofsd/passthrough_ll.c >>>> @@ -1619,7 +1619,11 @@ static void lo_getlk(fuse_req_t req, fuse_ino_t ino, >>>> return; >>>> } >>>> >>>> +#ifdef F_OFD_GETLK >>>> ret = fcntl(plock->fd, F_OFD_GETLK, lock); >>>> +#else >>>> + ret = fcntl(plock->fd, F_GETLK, lock); >>>> +#endif >>> >>> Hmm. Since this is in contrib, you are trying to compile something that >>> is independent of util/osdep.c (at least, I assume that's the case, as >>> contrib/virtiofsd/ is not even part of qemu.git master yet - in which >>> case, why is this not being squashed in to the patch introducing that >>> file, rather than sent standalone). On the other hand, that raises the >>> question - who is trying to use virtiofsd on a kernel that is too old to >>> provid F_OFD_GETLK? Isn't the whole point of virtiofsd to be speeding >>> up modern usage, at which point an old kernel is just gumming up the >>> works? It seems like you are better off letting compilation fail on a >>> system that is too old to support decent F_OFD_GETLK, rather than >>> silently falling back to something that is unsafe. >> >> It is, but I guess the answer here is someone wanted to build on RHEL7. > > although looking at the tools it went in 7.6 > > Dave > Yes, the compile error comes from kernel 3.10, and it seems necessary to solve this. I try to reuse qemu_lock_fd() to compat F_GETLK/F_SETLK, but its semantics differs from fcntl, so I think using #ifdef will be easier. We could delete F_GETLK/F_SETLK compat when virtiofsd is limited to be built in newer kernel. And I'm glad to hear from other developers. Thanks, Jun >> Dave >> >>> >>> -- >>> Eric Blake, Principal Software Engineer >>> Red Hat, Inc. +1-919-301-3226 >>> Virtualization: qemu.org | libvirt.org >>> >> >> >> >> >>> _______________________________________________ >>> Virtio-fs mailing list >>> Virtio-fs@redhat.com >>> https://www.redhat.com/mailman/listinfo/virtio-fs >> >> -- >> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK >> >> _______________________________________________ >> Virtio-fs mailing list >> Virtio-fs@redhat.com >> https://www.redhat.com/mailman/listinfo/virtio-fs > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > _______________________________________________ > Virtio-fs mailing list > Virtio-fs@redhat.com > https://www.redhat.com/mailman/listinfo/virtio-fs > . >