From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: Discrepancy in 'df' output between kernel 3.0 and 3.2 for ext4? Date: Thu, 14 Jun 2012 14:00:29 -0500 Message-ID: <4FDA34CD.9070404@redhat.com> References: <4FD8D731.9070008@cleversafe.com> <4FD8DB86.8030603@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Zachary Mark Return-path: Received: from mx1.redhat.com ([209.132.183.28]:42858 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752721Ab2FNTAe (ORCPT ); Thu, 14 Jun 2012 15:00:34 -0400 In-Reply-To: <4FD8DB86.8030603@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 6/13/12 1:27 PM, Eric Sandeen wrote: > On 6/13/12 1:08 PM, Zachary Mark wrote: >> Ext4 developers, >> >> I recently upgraded my kernel from 3.0.24 to 3.2.18, and discovered >> that df is now reporting different statistics for my ext4 file >> systems (sda1 is ext3 and unaffected). Notice the difference >> between the 1K-blocks column and Used column between kernel >> versions (Available remains constant, as it is merely Used >> subtracted from the total size): ... >> Is this discrepancy between the df outputs on the two kernel versions >> expected given my mount options? I decided to come to the list >> because I don't have the technical depth with regard to ext4 to be >> able to analyze the ext4_statfs changes that went into making >> bigalloc work, and I haven't found any reports of similar symptoms >> via web searches or the Documentation/filesystems/ext4.txt. This is > > https://bugzilla.redhat.com/show_bug.cgi?id=830412 just came in and is probably the same root cause. > > Thanks for the bisect! I'll let Ted worry about it for now, at least until I have more time. Ted, one thing that seems very weird to me. When using BSD-style df, which is supposed to ignore basic metadata overhead, shouldn't a freshly mkfs'd filesystem always show free blocks == total blocks? It doesn't do that either before or after your changes, which seems odd to me. Am I misunderstanding what "bsddf" is supposed to do? -eric