From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030639Ab2CBUp0 (ORCPT ); Fri, 2 Mar 2012 15:45:26 -0500 Received: from li9-11.members.linode.com ([67.18.176.11]:34185 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030614Ab2CBUpY (ORCPT ); Fri, 2 Mar 2012 15:45:24 -0500 Date: Fri, 2 Mar 2012 15:45:21 -0500 From: "Ted Ts'o" To: Neil Clarkson Cc: linux-kernel@vger.kernel.org Subject: Re: ext4 bug? last write time precedes last mount time on a writable volume! Message-ID: <20120302204521.GD22215@thunk.org> Mail-Followup-To: Ted Ts'o , Neil Clarkson , linux-kernel@vger.kernel.org References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on test.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 02, 2012 at 12:39:57PM +0000, Neil Clarkson wrote: > Isn't the s_wtime field of the ext4 superblock supposed to show the > time, in seconds since the epoch, of the last write? It isn't > happening! It shows the last time the superblock has been modified, and one of the things that we've been doing lately has been to optimize ext4 so that it writes to the superblock *much* less often. It was a performance bottleneck to be constantly updating the number of free blocks in the superblock each time we write to a new block, for example --- or update the superblock to update the number of free inodes each time we allocate a new inode. Is there a reason why you particularly care about s_wtime being updated? - Ted