Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757145AbZC0Whg (ORCPT ); Fri, 27 Mar 2009 18:37:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752711AbZC0Wh0 (ORCPT ); Fri, 27 Mar 2009 18:37:26 -0400 Received: from vms173001pub.verizon.net ([206.46.173.1]:38771 "EHLO vms173001pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751041AbZC0WhZ (ORCPT ); Fri, 27 Mar 2009 18:37:25 -0400 From: Gene Heskett Organization: Organization? Not detectable To: Theodore Tso , Linus Torvalds , Alan Cox , Matthew Garrett , Andrew Morton , David Rees , Jesper Krogh , Linux Kernel Mailing List Subject: Re: Linux 2.6.29 Date: Fri, 27 Mar 2009 18:37:08 -0400 User-Agent: KMail/1.11.1 (Linux/2.6.28.9; KDE/4.2.1; i686; ; ) References: <20090327112438.GQ6239@mit.edu> <200903271519.10921.gene.heskett@verizon.net> <20090327194836.GZ6239@mit.edu> In-reply-to: <20090327194836.GZ6239@mit.edu> MIME-version: 1.0 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7bit Content-disposition: inline Message-id: <200903271837.08755.gene.heskett@verizon.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3557 Lines: 84 On Friday 27 March 2009, Theodore Tso wrote: >On Fri, Mar 27, 2009 at 03:19:10PM -0400, Gene Heskett wrote: >> >You've said for a long that that ext3 is really bad in that it >> >inflicts this --- I agree with you. People should use other >> >filesystems which are better. This includes ext4, which is completely >> >format compatible with ext3. They don't even have to switch on >> >extents support to get better behaviour. Just mounting an ext3 >> >filesystem with ext4 will result in better behaviour. >> >> Ohkay. But in a 'make xconfig' of 2.6.28.9, how much of ext4 can be >> turned on without rendering the old ext3 fstab defaults incompatible >> should I be forced to boot a kernel with no ext4 support? > >Ext4 doesn't make any non-backwards compatible changes to the >filesystem. So if you just take an ext3 filesystem, and mount it as >ext4, it will work just fine; you will get delayed allocation, you >will get a slightly boosted write priority for kjournald, and then >when you unmount it, that filesystem will work *just* *fine* on a >kernel with no ext4 support. You can mount it as an ext3 filesystem. > >If you use tune2fs to enable various ext4 features, such as extents, >etc., then when you mount the filesystem as ext4, you will get the >benefit of extents for any new files which are created, and once you >do that, the filesystem can't be mounted on an ext3-only system, since >ext3 doesn't know how to deal with extents. > >And of course, if you want *all* of ext4's benefits, including the >full factor of 6-8 improvement in fsck times, then you will be best >served by creating a new ext4 filesystem from scratch and doing a >backup/reformat/restore pass. > >But if you're just annoyed by the large latencies in Ingo's "make >-j32" example, simply taking the ext3 filesystem and mounting it as >ext4 should make those problems go away. And it won't make any >incompatible changes to the filesystem. (This didn't use to be true >in the pre-2.6.26 days, but I insisted on getting this fixed so people >could always mount an ext2 or ext3 filesystems using ext4 without the >kernel making any irreversible filesystem format changes behind the >user's back.) > > - Ted Thanks Ted, I will build 2.6.28.9 with this: [root@coyote linux-2.6.28.9]# grep EXT .config [...] CONFIG_PAGEFLAGS_EXTENDED=y CONFIG_EXT2_FS=m CONFIG_EXT2_FS_XATTR=y CONFIG_EXT2_FS_POSIX_ACL=y # CONFIG_EXT2_FS_SECURITY is not set CONFIG_EXT2_FS_XIP=y CONFIG_EXT3_FS=m CONFIG_EXT3_FS_XATTR=y CONFIG_EXT3_FS_POSIX_ACL=y CONFIG_EXT3_FS_SECURITY=y CONFIG_EXT4_FS=y # CONFIG_EXT4DEV_COMPAT is not set # CONFIG_EXT4_FS_XATTR is not set CONFIG_GENERIC_FIND_NEXT_BIT=y Anything there that isn't compatible? I'll build that, but only switch the /amandatapes mount in fstab for testing tonight unless you spot something above. Thanks. >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html >Please read the FAQ at http://www.tux.org/lkml/ -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Losing your drivers' license is just God's way of saying "BOOGA, BOOGA!" -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/