From: Alex Tomas Subject: Re: [RFC] delayed allocation for ext4 Date: Fri, 29 Dec 2006 07:56:22 +0300 Message-ID: References: <20061223033123.GL44411608@melbourne.sgi.com> <20061229025246.GO44411608@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alex Tomas , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: Received: from fe02.tochka.ru ([62.5.255.22]:55956 "EHLO umail.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932674AbWL2E4h (ORCPT ); Thu, 28 Dec 2006 23:56:37 -0500 To: David Chinner In-Reply-To: <20061229025246.GO44411608@melbourne.sgi.com> (David Chinner's message of "Fri\, 29 Dec 2006 13\:52\:46 +1100") Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org >>>>> David Chinner (DC) writes: DC> So that mean's we'll have 2 separate mechanisms for marking DC> pages as delalloc. XFS uses the BH_delay flag to indicate DC> that a buffer (block) attached to the page is using delalloc. >> >> well, for blocksize=pagesize we can save 56 bytes on every page. DC> Sure, but it means that ext4 w/ delalloc won't work on lots of DC> machines.... it does not currenly. but I'm going to implement that. not sure whether it's worth to have two different codepaths for block size=page size and block size < page size. DC> FWIW, how does this mechanism deal with block size < page size? DC> Don't you have to track delalloc on a block basis rather than DC> a page basis? >> >> I'm still thinking how better to deal with that w/o much code duplication. DC> Code duplication in ext4, or across all filesystems? given what Andrew said about moving the code into VFS, it's more about all filesystems. thanks, Alex