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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 6C82FC433DF for ; Mon, 20 Jul 2020 14:54:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 528F122C9C for ; Mon, 20 Jul 2020 14:54:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728696AbgGTOx7 (ORCPT ); Mon, 20 Jul 2020 10:53:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726601AbgGTOx6 (ORCPT ); Mon, 20 Jul 2020 10:53:58 -0400 Received: from nautica.notk.org (ipv6.notk.org [IPv6:2001:41d0:1:7a93::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC0A7C061794 for ; Mon, 20 Jul 2020 07:53:58 -0700 (PDT) Received: by nautica.notk.org (Postfix, from userid 1001) id C2768C009; Mon, 20 Jul 2020 16:53:55 +0200 (CEST) Date: Mon, 20 Jul 2020 16:53:40 +0200 From: Dominique Martinet To: Jianyong Wu Cc: ericvh@gmail.com, hch@lst.de, dhowells@redhat.com, lucho@ionkov.net, v9fs-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, Kaly.Xin@arm.com, justin.he@arm.com, wei.chen@arm.com Subject: Re: [RFC PATCH 1/2] vfs: pass file down when getattr to avoid losing info. Message-ID: <20200720145340.GA13275@nautica> References: <20200720014622.37364-1-jianyong.wu@arm.com> <20200720014622.37364-2-jianyong.wu@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200720014622.37364-2-jianyong.wu@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jianyong Wu wrote on Mon, Jul 20, 2020: > Currently, getting attribute for a file represented by fd is always > by inode or path which may lead to bug for a certain network file system. > Adding file struct into struct kstat and assigning file for it in > vfs_statx_fd can avoid this issue. This change refers to struct istat. > > Signed-off-by: Jianyong Wu > --- > fs/stat.c | 1 + > include/linux/stat.h | 6 ++++++ > 2 files changed, 7 insertions(+) > > diff --git a/fs/stat.c b/fs/stat.c > index 44f8ad346db4..0dee5487f6d6 100644 > --- a/fs/stat.c > +++ b/fs/stat.c > @@ -147,6 +147,7 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat, > return -EINVAL; > > f = fdget_raw(fd); > + stat->filp = f.file; > if (f.file) { > error = vfs_getattr(&f.file->f_path, stat, > request_mask, query_flags); > diff --git a/include/linux/stat.h b/include/linux/stat.h > index 56614af83d4a..4755c528d49a 100644 > --- a/include/linux/stat.h > +++ b/include/linux/stat.h > @@ -48,6 +48,12 @@ struct kstat { > struct timespec64 btime; /* File creation time */ > u64 blocks; > u64 mnt_id; > + > + /* > + * Not an attribute, but an auxiliary info for filesystems wanting to > + * implement an fstat() like method. > + */ > + struct file *filp; Just, no ; don't touch this, it isn't likely to get accepted ever. file operations should all have a filp around already, we need to fix this in our code. (also missing quite a few Cc if you ever want to touch these bits, at least linux-fsdevel@) FWIW the problem has been discussed a few times previously. I'd appreciate if you could take over from Eric and Greg's old series that intended to fix that: https://lore.kernel.org/lkml/146659832556.15781.17414806975641516683.stgit@bahia.lan/ it introduced a race somewhere, but the idea looked good at the time so it's worth looking into. -- Dominique