From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Gud Subject: Re: [RFC][PATCH] ChunkFS: fs fission for faster fsck Date: Thu, 26 Apr 2007 11:44:51 -0500 Message-ID: <4630D703.6060602@ksu.edu> References: <17965.60841.900376.524639@gargle.gargle.HOWL> <17966.23512.363955.141489@gargle.gargle.HOWL> <17967.15531.450627.972572@gargle.gargle.HOWL> <20070425224710.GB16129@nifty> <20070426141455.GA6155@c2.user-mode-linux.org> <4630CAEC.2050909@ksu.edu> <20070426171134.5ce3bb6a@the-village.bc.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jeff Dike , Valerie Henson , Nikita Danilov , David Lang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, riel@surriel.com, zab@zabbo.net, arjan@infradead.org, suparna@in.ibm.com, brandon@ifup.org, karunasagark@gmail.com To: Alan Cox Return-path: Received: from smtp2.cc.ksu.edu ([129.130.7.16]:51358 "EHLO smtp2.cc.ksu.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753135AbXDZQqW (ORCPT ); Thu, 26 Apr 2007 12:46:22 -0400 In-Reply-To: <20070426171134.5ce3bb6a@the-village.bc.nu> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Alan Cox wrote: >> Preventive measures are taken to limit only one continuation inode per >> file per chunk. This can be done easily in the chunk allocation >> algorithm for disk space. Although I'm not quite sure what you mean by > > How are you handling the allocation in this situation, are you assuming > that a chunk is "out of bounds" because part of a file already lives on > it or simply keeping a single inode per chunk which has multiple sparse > pieces of the file on it ? > > ie if I write 0-8MB to chunk A and then 8-16 to chunk B can I write > 16-24MB to chunk A producing a single inode of 0-8 16-24, or does it have > to find another chunk to use ? Hello Alan, You re-use the same inode with multiple sparse pieces. This way you avoid hopping around continuation inodes and coming back to same chunk with which you started but this time on a different continuation inode. This may not be I/O intensive for successive traversals if the continuation inodes are pinned in the memory, but it certainly is a waste of resource - inodes. Not allowing this would make worst case of every file having a continuation inode in every chunk, even worse; may be like only single file exist in the file system and rest all inodes in all chunks (including file's own chunk) are continuation inodes. AG -- May the source be with you. http://www.cis.ksu.edu/~gud