From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out4-smtp.messagingengine.com ([66.111.4.28]:39842 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751387AbdCAV12 (ORCPT ); Wed, 1 Mar 2017 16:27:28 -0500 Message-Id: <1488399744.4117222.897262296.4F6CBA5A@webmail.messagingengine.com> From: Colin Walters To: Josh England , Amir Goldstein Cc: "linux-fsdevel" , linux-unionfs@vger.kernel.org, Miklos Szeredi MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" References: In-Reply-To: Subject: Re: overlayfs: allowing for changes to lowerdir Date: Wed, 01 Mar 2017 15:22:24 -0500 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Feb 28, 2017, at 02:08 PM, Josh England wrote: > It has always been an > annoyance to have to find the little bits and pieces in the OS (think > of a full RHEL/CentOS distro) that require the ability to write > somewhere As part of driving the [OSTree](https://ostree.readthedocs.io/en/latest/) model into Fedora/CentOS (well really rpm-ostree, which is part of Atomic Host), we have a read-only bind mount over /usr, and the only two writable directories are /etc and /var. In a diskless mode, then you could have /usr as a read-only NFS/cachefiles mount, and use tmpfs for /etc and /var. Ideally /etc can be read-only too during operation but that is definitely one where we hit things like LVM userspace writing there in the background: https://bugzilla.redhat.com/show_bug.cgi?id=1366584 But if something required writing to /usr at runtime in Fedora/CentOS that should be considered a bug.