From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e34.co.us.ibm.com ([32.97.110.152]:59157 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753874Ab2LRW04 (ORCPT ); Tue, 18 Dec 2012 17:26:56 -0500 Received: from /spool/local by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 18 Dec 2012 15:26:55 -0700 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id ABD2F19D8042 for ; Tue, 18 Dec 2012 15:26:52 -0700 (MST) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id qBIMQpYW229968 for ; Tue, 18 Dec 2012 15:26:52 -0700 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id qBIMQpYf031189 for ; Tue, 18 Dec 2012 15:26:51 -0700 Message-ID: <50D0EDAA.3090202@linux.vnet.ibm.com> Date: Tue, 18 Dec 2012 14:26:50 -0800 From: Wade Cline MIME-Version: 1.0 To: miaox@cn.fujitsu.com CC: bo.li.liu@oracle.com, linux-btrfs@vger.kernel.org, cmm@linux.vnet.ibm.com Subject: Re: [PATCH] [RFC v2] Btrfs: Subpagesize blocksize (WIP). References: <1355814805-13935-1-git-send-email-clinew@linux.vnet.ibm.com> <20121218073050.GA19332@liubo.cn.oracle.com> <50D02E0A.8080505@cn.fujitsu.com> In-Reply-To: <50D02E0A.8080505@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 12/18/2012 12:49 AM, Miao Xie wrote: > On tue, 18 Dec 2012 15:30:51 +0800, Liu Bo wrote: >> On Mon, Dec 17, 2012 at 11:13:25PM -0800, clinew@linux.vnet.ibm.com wrote: >>> From: Wade Cline >>> >>> v1 -> v2: >>> - Added Signed-off-by tag (it's kind of important). >>> >>> This patch is only an RFC. My internship is ending and I was hoping >>> to get some feedback and incorporate any suggestions people may >>> have before my internship ends along with life as we know it (this >>> Friday). >>> >>> The filesystem should mount/umount properly but tends towards the >>> explosive side when writes start happening. My current focus is on >>> checksumming issues and also an error when releasing extent buffers >>> when creating a large file with 'dd'... and probably any other >>> method. There's still a significant amount of work that needs to be >>> done before this should be incorporated into mainline. >>> >>> A couple of notes: >>> - Based off of Josef's btrfs-next branch, commit >>> 8d089a86e45b34d7bc534d955e9d8543609f7e42 >>> - C99-style comments are "meta-comments" where I'd like more >>> feedback; they aren't permanent but make 'checkpatch' moan. >>> - extent_buffer allocation and freeing need their code paths >>> merged; they're currently in separate functions and are both >>> very ugly. >>> - The patch itself will eventually need to be broken down >>> into smaller pieces if at all possible... >> >> Could you please first elaborate why we need this subpagesize stuff and >> any user case in this patch's commit log? >> Or Am I missing something? > > It is used on the machines on which the page size is larger than 4KB (Such as powerpc) > > Thanks > Miao Yeah. Basically, if we create a btrfs filesystem with a 4k blocksize then that filesystem is incompatible with architectures such as PowerPC and MIPS which have a page size larger than 4k. -Wade