From: Andreas Dilger Subject: Re: [RFC] Add new extent structure in ext4 Date: Wed, 25 Jan 2012 16:03:09 -0700 Message-ID: <4C9A2CF5-A980-43A0-9D43-56EA45DA096C@dilger.ca> References: <20120125224847.GT15102@dastard> Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: Robin Dong , Ted Ts'o , Ext4 Developers List To: Dave Chinner Return-path: Received: from idcmail-mo2no.shaw.ca ([64.59.134.9]:64804 "EHLO idcmail-mo2no.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750865Ab2AYXDL convert rfc822-to-8bit (ORCPT ); Wed, 25 Jan 2012 18:03:11 -0500 In-Reply-To: <20120125224847.GT15102@dastard> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2012-01-25, at 3:48 PM, Dave Chinner wrote: > On Mon, Jan 23, 2012 at 08:51:53PM +0800, Robin Dong wrote: >> Hi Ted, Andreas and the list, >> >> After the bigalloc-feature is completed in ext4, we could have much more >> big size of block-group (also bigger continuous space), but the extent >> structure of files now limit the extent size below 128MB, which is not >> optimal. >> >> We could solve the problem by creating a new extent format to support >> larger extent size, which looks like this: >> >> struct ext4_extent2 { >> __le64 ee_block; /* first logical block extent covers */ >> __le64 ee_start; /* starting physical block */ >> __le32 ee_len; /* number of blocks covered by extent */ >> __le32 ee_flags; /* flags and future extension */ >> }; >> >> struct ext4_extent2_idx { >> __le64 ei_block; /* index covers logical blocks from 'block' */ >> __le64 ei_leaf; /* pointer to the physical block of the next level */ >> __le32 ei_flags; /* flags and future extension */ >> __le32 ei_unused; /* padding */ >> }; >> >> I think we could keep the structure of ext4_extent_header and add new >> imcompat flag EXT4_FEATURE_INCOMPAT_EXTENTS2. >> >> The new extent format could support 16TB continuous space and larger volumes. >> >> What's your opinion? > > Just use XFS. Thanks for your troll. If you have something actually useful to contribute, please feel free to post. Otherwise, this is a list for ext4 development. I don't encourage XFS users to switch to ext4 (or ZFS, for that matter, since ZFS can do a lot of things that just aren't possible for XFS, and is now available for Linux) on your mailing lists, and I'd appreciate the same courtesy here... Cheers, Andreas