From: Christoph Hellwig Subject: Re: [RFC] delayed allocation for ext4 Date: Sat, 23 Dec 2006 09:27:18 +0000 Message-ID: <20061223092718.GA26276@infradead.org> References: <20061223033123.GL44411608@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 pentafluge.infradead.org ([213.146.154.40]:50947 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752789AbWLWJ1X (ORCPT ); Sat, 23 Dec 2006 04:27:23 -0500 To: David Chinner Content-Disposition: inline In-Reply-To: <20061223033123.GL44411608@melbourne.sgi.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sat, Dec 23, 2006 at 02:31:23PM +1100, David Chinner wrote: > > - ext4-delayed-allocation.patch > > delayed allocation itself, enabled by "delalloc" mount option. > > extents support is also required. currently it works only > > with blocksize=pagesize. > > Ah, that's why you can get away with a page flag - you've ignored > the partial page delay state problem. Any plans to use the > existing method in the future so we will be able to use ext4 delalloc > on machines with a page size larger than 4k? I think fixing this up for blocksize < pagesize is an absolute requirement to get things merged. We don't need more filesystems that are crippled on half of our platforms. Note that recording delayed alloc state at a page granularity in addition to just the buffer heads has a lot of advantages aswell and would help xfs, too. But I think it makes a lot more sense to record it as a radix tree tag to speed up the gang lookups for delalloc conversion.