From mboxrd@z Thu Jan 1 00:00:00 1970 From: Qi Yong Subject: Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3 Date: Tue, 20 Jun 2006 14:15:27 +0800 Message-ID: <4497927F.4070307@fc-cn.com> References: <1149816055.4066.60.camel@dyn9047017069.beaverton.ibm.com> <4488E1A4.20305@garzik.org> <20060609083523.GQ5964@schatzie.adilger.int> <44898EE3.6080903@garzik.org> <1149885135.5776.100.camel@sisko.sctweedie.blueyonder.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "Stephen C. Tweedie" , Jeff Garzik , Andreas Dilger , Andrew Morton , "ext2-devel@lists.sourceforge.net" , linux-kernel , Mingming Cao , linux-fsdevel@vger.kernel.org, alex@clusterfs.com Return-path: Received: from fc-cn.com ([218.25.172.144]:58632 "HELO mail.fc-cn.com") by vger.kernel.org with SMTP id S965076AbWFTGPd (ORCPT ); Tue, 20 Jun 2006 02:15:33 -0400 To: Linus Torvalds In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Linus Torvalds wrote: >On Fri, 9 Jun 2006, Stephen C. Tweedie wrote: > > >>When is the Linux syscall interface enough? When should we just bump it >>and cut out all the compatibility interfaces? >> >>No, we don't; we let people configure certain obsolete bits out (a.out >>support etc), but we keep it in the tree despite the indirection cost to >>maintain multiple interfaces etc. >> >> > >Right. WE ADD NEW SYSTEM CALLS. WE DO NOT EXTEND THE OLD ONES IN WAYS THAT >MIGHT BREAK OLD USERS. > >Your point was exactly what? > >Btw, where did that 2TB limit number come from? Afaik, it should be 16TB >for a 4kB filesystem, no? > > Partition tables describe partitions in units of one sector. 2^(32+9) = 2T To prevent integer overflow, we should use only 31 bits of a 32-bit integer. 2^(31+12) = 8T There's _terrible_ hacks to really get to 16T. -- qiyong