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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 A7048C433E0 for ; Mon, 8 Feb 2021 20:58:44 +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 1724064E05 for ; Mon, 8 Feb 2021 20:58:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1724064E05 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]:57808 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l9DcI-0000Qo-VD for qemu-devel@archiver.kernel.org; Mon, 08 Feb 2021 15:58:42 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:34268) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l9A7D-0005et-Vx for qemu-devel@nongnu.org; Mon, 08 Feb 2021 12:14:24 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:31990) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l99yU-0003hh-QO for qemu-devel@nongnu.org; Mon, 08 Feb 2021 12:05:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612803921; 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=uH1Lof+Oo+kofscgo/Mc0xgLYxTSWwumLWHJoNsUQrc=; b=WLPERNmqCtrfx0Jz4/AFPqEEDfeDUn+PHKZw2eliaE27XhJC6SGXkqTQabWj7iND1DiuIq 77Nso9bEnVo73KS/iQQ9d2Rs+f6TP/QZ7xRnKg7FQo7/8JotTP2KAiwKtjvA3yIOktNUO8 jxFRkq5TEa/XG8U5Yfb5qd8lwmD/xO4= 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-304-p2f0OUR1OpuzFusLJY3HtQ-1; Mon, 08 Feb 2021 12:05:19 -0500 X-MC-Unique: p2f0OUR1OpuzFusLJY3HtQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CA9711084432 for ; Mon, 8 Feb 2021 17:05:09 +0000 (UTC) Received: from work-vm (ovpn-115-22.ams2.redhat.com [10.36.115.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9FAD47A392; Mon, 8 Feb 2021 17:05:08 +0000 (UTC) Date: Mon, 8 Feb 2021 17:05:05 +0000 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [Virtio-fs] [PATCH v2 1/2] virtiofsd: Save error code early at the failure callsite Message-ID: <20210208170505.GD3033@work-vm> References: <20201112182418.25395-1-vgoyal@redhat.com> <20201112182418.25395-2-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: <20201112182418.25395-2-vgoyal@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.57, 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_H4=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: 2.1.23 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" * Vivek Goyal (vgoyal@redhat.com) wrote: > Change error code handling slightly in lo_setattr(). Right now we seem > to jump to out_err and assume that "errno" is valid and use that to > send reply. > > But if caller has to do some other operations before jumping to out_err, > then it does the dance of first saving errno to saverr and the restore > errno before jumping to out_err. This makes it more confusing. > > I am about to make more changes where caller will have to do some > work after error before jumping to out_err. I found it easier to > change the convention a bit. That is caller saves error in "saverr" > before jumping to out_err. And out_err uses "saverr" to send error > back and does not rely on "errno" having actual error. > > Signed-off-by: Vivek Goyal Yes, that looks OK, so Reviewed-by: Dr. David Alan Gilbert but please can you send a rebased version, Stefan's recent security fix changes it around the openat. Dave > --- > tools/virtiofsd/passthrough_ll.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index ec1008bceb..6407b1a2e1 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -686,6 +686,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > res = fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0); > } > if (res == -1) { > + saverr = errno; > goto out_err; > } > } > @@ -695,6 +696,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > > res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); > if (res == -1) { > + saverr = errno; > goto out_err; > } > } > @@ -707,15 +709,15 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > sprintf(procname, "%i", ifd); > truncfd = openat(lo->proc_self_fd, procname, O_RDWR); > if (truncfd < 0) { > + saverr = errno; > goto out_err; > } > } > > res = ftruncate(truncfd, attr->st_size); > + saverr = res == -1 ? errno : 0; > if (!fi) { > - saverr = errno; > close(truncfd); > - errno = saverr; > } > if (res == -1) { > goto out_err; > @@ -748,6 +750,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > res = utimensat(lo->proc_self_fd, procname, tv, 0); > } > if (res == -1) { > + saverr = errno; > goto out_err; > } > } > @@ -756,7 +759,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, > return lo_getattr(req, ino, fi); > > out_err: > - saverr = errno; > lo_inode_put(lo, &inode); > fuse_reply_err(req, saverr); > } > -- > 2.25.4 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK