From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [GIT PULL] overlayfs update for 4.18 Date: Sun, 10 Jun 2018 06:54:38 +0100 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 Return-path: Content-Disposition: inline In-Reply-To: <20180609065208.GA31572@infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: Miklos Szeredi , Linus Torvalds , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org List-Id: linux-unionfs@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.