From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id XamjKlO9HFujYwAAmS7hNA ; Sun, 10 Jun 2018 05:55:53 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id BE2DF607BB; Sun, 10 Jun 2018 05:55:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 454E7605A5; Sun, 10 Jun 2018 05:55:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 454E7605A5 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=ZenIV.linux.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932236AbeFJFzs (ORCPT + 25 others); Sun, 10 Jun 2018 01:55:48 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:54516 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932085AbeFJFzq (ORCPT ); Sun, 10 Jun 2018 01:55:46 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1fRtJG-0004G4-J5; Sun, 10 Jun 2018 05:54:44 +0000 Date: Sun, 10 Jun 2018 06:54:38 +0100 From: Al Viro To: Christoph Hellwig Cc: Miklos Szeredi , Linus Torvalds , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org Subject: Re: [GIT PULL] overlayfs update for 4.18 Message-ID: <20180610055326.GR30522@ZenIV.linux.org.uk> References: <20180608121330.GG23785@veci.piliscsaba.redhat.com> <20180609065208.GA31572@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180609065208.GA31572@infradead.org> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 08, 2018 at 11:52:08PM -0700, Christoph Hellwig wrote: > On Fri, Jun 08, 2018 at 02:13:30PM +0200, Miklos Szeredi wrote: > > Hi Linus, > > > > Please pull from: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git tags/ovl-update-4.18 > > > > This contains two new features: > > > > 1) Stack file operations: this allows removal of several hacks from the > > VFS, proper interaction of read-only open files with copy-up, > > possibility to implement fs modifying ioctls properly, and others. > > Which includews all kinds of NAKed or at least non-acked VFS changes. Umm... The worst of yours had been ->pre_mmap(), right? He *did* drop that... > Please get these through Als tree after proper review first. OK, summary of sort (see fsdevel thread for details): * path_open() is dubious; why not simply use vfsmount/dentry from the right layer when opening an underlying file? Then it would be vfs_open()... * ovl_mmap() is broken, plain and simple. Failure ends up leaking a layer struct file *and* doing double fput() on overlayfs one. * ovl_mmap() is also trivially DoSable - you can trigger tons and tons of reopens, each sticking a new (writable layer) struct file into a vma. We *do* want some scheme avoiding once-per-operations reopens in the copied-up-after-r/o-open case. See possible kinda-sorta solution on fsdevel; I'm not sure I like it, though. The rest is pretty minor.