From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755628AbYEZRi6 (ORCPT ); Mon, 26 May 2008 13:38:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754272AbYEZRiu (ORCPT ); Mon, 26 May 2008 13:38:50 -0400 Received: from styx.suse.cz ([82.119.242.94]:45546 "EHLO mail.suse.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753717AbYEZRiu (ORCPT ); Mon, 26 May 2008 13:38:50 -0400 Date: Mon, 26 May 2008 19:38:48 +0200 From: Jan Kara To: Bart Van Assche Cc: Oliver Neukum , Theodore Tso , Ingo Molnar , Jan Kara , Arjan van de Ven , Linux Kernel Mailing List , Linus Torvalds , Greg KH , Andrew Morton Subject: Re: Top 10 bugs/warnings for the week of March 23rd, 2008 Message-ID: <20080526173848.GM32407@duck.suse.cz> References: <4836EE8C.1010200@linux.intel.com> <20080526164858.GA24098@elte.hu> <20080526170147.GB9893@mit.edu> <200805261909.59032.oliver@neukum.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 26-05-08 19:28:23, Bart Van Assche wrote: > On Mon, May 26, 2008 at 7:09 PM, Oliver Neukum wrote: > > Am Montag 26 Mai 2008 19:01:48 schrieb Theodore Tso: > >> If the USB stack folks would like to work on how to recognize that > >> it's the same USB stick that had been previously pulled, so that it > >> gets the same block device, and we can decide for how long we should > >> keep dirty buffers around associated with a pulled USB stick, we can > >> certainly have that conversation. :-) > > > > Even if we could tell whether the device has remained the same, how > > would we know the medium wasn't exchanged? > > Looking at the filesystem UUID could help -- this is an ID that is > present as data on the disk, and that is even independent of the bus > type. See also /dev/disk/by-uuid. Yes, but as Oliver wrote if someone modified the filesystem in the mean time, you won't notice it - UUID doesn't help here. > For the journaling filesystems I am familiar with the default value > for the commit parameter is 5 seconds. Would it be a good idea to > leave the default to 5s for non-removable devices, and to change this > default to 1s for removable devices ? I don't think it's a good idea: 1) You'd even more stress wear-leveling of USB flash drives - btw, given their sizes it does not make much sence to use ext3 on your USB stick. I still use VFAT/ext2 there. 2) You'd probably notice performance decrease because of more journaling overhead. Honza -- Jan Kara SUSE Labs, CR