From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 01 Aug 2007 04:17:28 -0700 (PDT) Received: from mx1.suse.de (mx1.suse.de [195.135.220.2]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l71BHLbm016715 for ; Wed, 1 Aug 2007 04:17:24 -0700 Subject: Re: RFC: log record CRC validation References: <20070725092445.GT12413810@sgi.com> <46A7226D.8080906@sgi.com> <46A8DF7E.4090006@agami.com> <20070726233129.GM12413810@sgi.com> <46A94963.7000103@agami.com> <20070727065930.GT12413810@sgi.com> <46AFD88E.9070403@agami.com> <20070801022418.GR31489@sgi.com> From: Andi Kleen Date: 01 Aug 2007 14:11:58 +0200 In-Reply-To: <20070801022418.GR31489@sgi.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: David Chinner Cc: Michael Nishimoto , markgw@sgi.com, xfs-dev , xfs-oss David Chinner writes: > I haven't looked at great depth into other structures in terms of > implementation details. I know that if we use a 16 bit CRC on > directories we can get away without a on-disk format change as the > xfs_da_blkinfo structure has 16 bits of padding. However, given that > directory block size can reach 64k, a CRC16 check is really only > capable of single bit error detection. Hence I think we really need > CRC32 here which means an on-disk format change. When the directory format is changed it would be nice to also support DT_* types at the same time. They can speed up some operations nicely because file system walkers can avoid a stat() (and seek to the inode) just to find out if a name is a directory or not. Right now there is no space for this unfortunately. -Andi