From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail07.adl2.internode.on.net ([150.101.137.131]:11204 "EHLO ipmail07.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751373AbcBUVTg (ORCPT ); Sun, 21 Feb 2016 16:19:36 -0500 Date: Mon, 22 Feb 2016 08:19:21 +1100 From: Dave Chinner To: Richard Weinberger Cc: Pushpal Sidhu , linux-fsdevel , "linux-mtd@lists.infradead.org" Subject: Re: ubifs+overlayfs Message-ID: <20160221211921.GA25832@dastard> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sun, Feb 21, 2016 at 03:27:18PM +0100, Richard Weinberger wrote: > Cc'ing linux-mtd. > > On Sat, Feb 20, 2016 at 1:02 AM, Pushpal Sidhu wrote: > > It seems that overlayfs requires RENAME_WHITEOUT and RENAME_EXCHANGE. > > However, these two flags aren't currently supported in ubifs (or > > anything other than ext4, f2fs, and xfs). This causes any atomic > > renames to fail (e.g. using 'mv' command). > > Hmm, right. I always thought overlayfs does checks at mount time. > But apparently I was wrong. > Thanks for pointing this out. It doesn't check any of the requirements it has from the underlying filesystem. e.g. overlay requires DT_CHR for detecting whiteouts, but it doesn't check if the upper filesystem actually supports DT_CHR or not, and hence will fail to detect whiteouts correctly on such filesystems. I've been pushing people to fix this, so maybe patches will appear in the not too distant future... Cheers, Dave. -- Dave Chinner david@fromorbit.com