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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT autolearn=unavailable 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 ACC5FC48BD3 for ; Wed, 26 Jun 2019 15:37:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82DCE208E3 for ; Wed, 26 Jun 2019 15:37:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="Mr0csDp/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728204AbfFZPhN (ORCPT ); Wed, 26 Jun 2019 11:37:13 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:38166 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726984AbfFZPhM (ORCPT ); Wed, 26 Jun 2019 11:37:12 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5QFXoje151326; Wed, 26 Jun 2019 15:35:49 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=9G5PiDG0S7gskQAEA+1rG18NFPpT+WoUOG9H+94vGJo=; b=Mr0csDp/6gFDwuuR4WcTjSwEQhZRUvDp0wq3YeKCIR/ppK1h93X/GLwv9+Y3cvXAo/We nBBPCWspqpkQf8Ya9/6yEHadZ9h5/AK9JEwgQLT2OJ63YoS19u03moZ7UXD928KK75Tw IYGgl4G6FFtMYGPdEh6jhDWXC8Gi+dRHPoIK4U9EU9fQhY9zQayETLpTGjqGl7XpA008 xvtm1tvTyzmAnCbVLIgcaAr+22UL4c7SemsbRVUkLI8sB/S8GoHCuFEiRRnlmAb3SWPf RtSXc0WG3A/565vb1OMt7fUapvm0eYSNFeeM5VPPlY8RA+hUmYz247kCS97awaKxof1X 1A== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2130.oracle.com with ESMTP id 2t9brtb5ka-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 15:35:48 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5QFZWnl185666; Wed, 26 Jun 2019 15:35:48 GMT Received: from pps.reinject (localhost [127.0.0.1]) by aserp3030.oracle.com with ESMTP id 2t9accs0fq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 26 Jun 2019 15:35:48 +0000 Received: from aserp3030.oracle.com (aserp3030.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x5QFZlgQ186348; Wed, 26 Jun 2019 15:35:47 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 2t9accs0fn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 15:35:47 +0000 Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x5QFZjvI031893; Wed, 26 Jun 2019 15:35:45 GMT Received: from localhost (/10.159.137.246) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 26 Jun 2019 08:35:45 -0700 Date: Wed, 26 Jun 2019 08:35:42 -0700 From: "Darrick J. Wong" To: Al Viro Cc: matthew.garrett@nebula.com, yuchao0@huawei.com, tytso@mit.edu, shaggy@kernel.org, ard.biesheuvel@linaro.org, josef@toxicpanda.com, hch@infradead.org, clm@fb.com, adilger.kernel@dilger.ca, jk@ozlabs.org, jack@suse.com, dsterba@suse.com, jaegeuk@kernel.org, cluster-devel@redhat.com, jfs-discussion@lists.sourceforge.net, linux-efi@vger.kernel.org, Jan Kara , reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 2/5] vfs: create a generic checking function for FS_IOC_FSSETXATTR Message-ID: <20190626153542.GE5171@magnolia> References: <156151632209.2283456.3592379873620132456.stgit@magnolia> <156151633829.2283456.834142172527987802.stgit@magnolia> <20190626041133.GB32272@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190626041133.GB32272@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9299 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906260182 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Jun 26, 2019 at 05:11:33AM +0100, Al Viro wrote: > On Tue, Jun 25, 2019 at 07:32:18PM -0700, Darrick J. Wong wrote: > > --- a/fs/btrfs/ioctl.c > > +++ b/fs/btrfs/ioctl.c > > @@ -373,10 +373,9 @@ static int check_xflags(unsigned int flags) > > static int btrfs_ioctl_fsgetxattr(struct file *file, void __user *arg) > > { > > struct btrfs_inode *binode = BTRFS_I(file_inode(file)); > > - struct fsxattr fa; > > - > > - memset(&fa, 0, sizeof(fa)); > > - fa.fsx_xflags = btrfs_inode_flags_to_xflags(binode->flags); > > + struct fsxattr fa = { > > + .fsx_xflags = btrfs_inode_flags_to_xflags(binode->flags), > > + }; > > Umm... Sure, there's no padding, but still - you are going to copy that thing > to userland... How about > > static inline void simple_fill_fsxattr(struct fsxattr *fa, unsigned xflags) > { > memset(fa, 0, sizeof(*fa)); > fa->fsx_xflags = xflags; > } > > and let the compiler optimize the crap out? The v2 series used to do that, but Christoph complained that having a helper for a two-line memset and initialization was silly[1] so now we have this version. I don't mind reinstating it as a static inline helper, but I'd like some input from any of the btrfs developers (or you, Al) about which form is preferred. --D [1] https://lkml.org/lkml/2019/6/25/533