From: tytso@mit.edu Subject: Re: ext4 df free space reporting not reliable? Date: Sun, 13 Jun 2010 14:58:59 -0400 Message-ID: <20100613185858.GB8055@thunk.org> References: <20100613093807.GA31407@basil.fritz.box> <69DFE925-D32D-4CAA-B734-545DE0515FCE@mit.edu> <20100613103451.GF31464@basil.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Andi Kleen Return-path: Received: from thunk.org ([69.25.196.29]:38918 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754228Ab0FMS7E (ORCPT ); Sun, 13 Jun 2010 14:59:04 -0400 Content-Disposition: inline In-Reply-To: <20100613103451.GF31464@basil.fritz.box> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Jun 13, 2010 at 12:34:51PM +0200, Andi Kleen wrote: > > Are you creating the files as root? Sounds like the standard reserved > > blocks behavior that's been around since ext3, ext2, BSD's ufs, etc... > > Yes everything is root. > > I would expect root df to not report the reservation. Is that not the case? No, the reservation is always reported, regardless of which user ID is executing the statfs(2) system call. This has always been true, going all the way back to BSD 4.3. I could see the argument for doing this differently, but I could also see that being very surprising for people to see different results depending on whether they are running df from a setuid shell or not. I'm not aware of any Unix system which has implemented the root-only reservation system which has done this. - Ted