From: Theodore Tso Subject: Re: [PATCH] Ext4 Documentation updates. Date: Thu, 3 Jul 2008 21:30:59 -0400 Message-ID: <20080704013059.GL30506@mit.edu> References: <20080702172200.14990.37737.stgit@rx8> <1215035155.6788.43.camel@mingming-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Jose R. Santos" , linux-ext4@vger.kernel.org To: Mingming Cao Return-path: Received: from www.church-of-our-saviour.ORG ([69.25.196.31]:59825 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757345AbYGDBbE (ORCPT ); Thu, 3 Jul 2008 21:31:04 -0400 Content-Disposition: inline In-Reply-To: <1215035155.6788.43.camel@mingming-laptop> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Jul 02, 2008 at 02:45:55PM -0700, Mingming Cao wrote: > +In ext4/JBD2 this ordered mode implementation is different than ext3/JBD > +ordered mode. First it get rid of using buffer heads to enforce the ordering > +between metadata change with the related data chage. Instead, in the new > +ordering mode, it keeps track of per transaction journalled inode list, and > +flush all the dirty pages for those inodes, when committing that transaction. > +Second, the new ordered mode reverse the lock ordering of the page lock and > +transaction lock, to fixing the locking issue in the new mode, and also provide > +easy support for delayed allocation over the new ordered mode This is implementation detail that doesn't belong in Documentation/filesystems/ext4.txt; a user won't care about this kind of detail. However, it is *perfect* for the the (as-yet-undocumented) patch comment for the new ordered mode patch in the series. I rewrote it for gramatical correctness and clarity thusly, for the patch delalloc-new-ordered-mode.patch: This provides a new ordered mode implementation which gets rid of using buffer heads to enforce the ordering between metadata change with the related data chage. Instead, in the new ordering mode, it keeps track of all of the inodes touched by each transaction on a list, and when that transaction is committed, it flushes all of the dirty pages for those inodes. In addition, the new ordered mode reverses the lock ordering of the page lock and transaction lock, which provides easier support for delayed allocation. - Ted