From: Andreas Dilger Subject: Re: [PATCH] dir_index: error out instead of BUG on corrupt hash dir limit Date: Fri, 10 Aug 2007 12:19:02 -0600 Message-ID: <20070810181901.GT6689@schatzie.adilger.int> References: <46BB8830.3060009@redhat.com> <46BB9826.6040904@redhat.com> <20070810082904.GL6689@schatzie.adilger.int> <46BC8D61.9080400@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 development To: Eric Sandeen Return-path: Received: from mail.clusterfs.com ([74.0.229.162]:35589 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757515AbXHJSTA (ORCPT ); Fri, 10 Aug 2007 14:19:00 -0400 Content-Disposition: inline In-Reply-To: <46BC8D61.9080400@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Aug 10, 2007 11:08 -0500, Eric Sandeen wrote: > Andreas Dilger wrote: > > I'd like to see the actual corruption, to find out why the hash-type > > check didn't find it. If it is because LDISKFS_DX_HASH_LEGACY hash > > type is zero, I think we can disable that hash type, and people will > > just have to run "e2fsck -fD" to reindex to a new type. This hasn't > > been on for a long, long time. > > So far I haven't been able to find it in any of the images provided. > > We may have to dual-boot windows & run the crummy driver for a while to > track it down, if we care enough. > > Which reminds me, what do you think of the wording in the ext3_warning I > added - is "corruption" appropriate? The other warnings aren't quite so > stark... hmm maybe we should add "have you been running a binary-only > driver for windows?" :) It would be interesting to check if mounting a dir_index filesystem on linux with ext2 has the same problem. It _should_ have been that if rec_len % 4 == 0 (i.e. any valid dirent) we would fail the hash_version check, but we left in the DX_HASH_LEGACY (0) and that check is blown. The unused_flags & 1 is only hit for a dirent with DT_FIFO (no good). The remaining check is indirect_levels > 1, which should be hit for any dirent with name_len > 1 (i.e. most, but not all). So, I think you could reproduce this in linux by making an indexed directory in ext3/4, mounting it as ext2, and then creating a 1-character filename in the directory, or any length filename and then deleting it. In addition to your extra check, I think we should remove DX_HASH_LEGACY check, to catch this more easily. If (hash_version % 4 == 0) the warning shouldn't even be printed. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.