From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: [PATCH, RFC] Add new "development flag" to the ext4 filesystem Date: Wed, 30 Jan 2008 17:48:21 -0500 Message-ID: <20080130224820.GA20529@mit.edu> References: <20080122231707.GA21968@mit.edu> <47A0F98C.1080304@yahoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: supersud501 Return-path: Received: from www.church-of-our-saviour.org ([69.25.196.31]:47607 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753132AbYA3Wsa (ORCPT ); Wed, 30 Jan 2008 17:48:30 -0500 Content-Disposition: inline In-Reply-To: <47A0F98C.1080304@yahoo.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Jan 30, 2008 at 11:26:20PM +0100, supersud501 wrote: > > how can i set this "flag" on my filesystem? i've never set any flags before > so i just removed the code from ext4-module to mount my filesystems, but > setting the flag once would make it easier i think :) If you have e2fsprogs 1.40.5, you set at mke2fs time via "mke2fs -E test_fs ...". If you haven't mounted the filesystem using ext4 yet, you can also convert an existing filesystem using "tune2fs -E test_fs /dev/hdXXX". At least with e2fsprogs 1.40.5, it won't work with a filesystem with extents enabled because tune2fs will refuse to touch such a filesystem. (And you don't want to use e2fsprogs 1.40.5 with ext4 anyway, since e2fsck in 1.40.5 doesn't understand extents yet.) You can manually set the flag using debugfs: # debugfs -w /dev/hdXX debugfs: set_super_value s_flags 4 debugfs: quit (Or, if you're lazy, you can also type the shorthand "ssv flags 4" to debugfs.) With e2fsprogs 1.40.5, if the test_fs flag is set, then blkid will return a filesystem type ext4dev, such that if your mount is configured to use blkid (instead of vol_id), it will automatically use ext4dev to mount a filesystem that has (a) a journal (since ext4 currently requires a journal), and (b) the test_fs flag set. This makes it easier for people who are testing ext4, since they will just be able to do something like: # mke2fs -j -E test_fs /dev/mapper/lvmset-test # mount /dev/mapper/lvmset-test .. and /dev/mapper/lvmset-test will automatically be mounted using ext4. - Ted