From: Andreas Dilger Subject: Re: [PATCH] ext34: ensure do_split leaves enough free space in both blocks Date: Mon, 17 Sep 2007 14:57:38 -0600 Message-ID: <20070917205738.GQ2990@schatzie.adilger.int> References: <46EEA5F4.3030806@redhat.com> <46EEB7A4.9040903@sandeen.net> <20070917133020.5fc4650c.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Sandeen , Eric Sandeen , ext4 development , Linux Kernel Mailing List , hooanon05@yahoo.co.jp, Theodore Ts'o To: Andrew Morton Return-path: Received: from mail.clusterfs.com ([74.0.229.162]:48362 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756764AbXIQU5O (ORCPT ); Mon, 17 Sep 2007 16:57:14 -0400 Content-Disposition: inline In-Reply-To: <20070917133020.5fc4650c.akpm@linux-foundation.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sep 17, 2007 13:30 -0700, Andrew Morton wrote: > On Mon, 17 Sep 2007 12:21:40 -0500 > > Eric Sandeen wrote: > > > The do_split() function for htree dir blocks is intended to split a > > > leaf block to make room for a new entry. It sorts the entries in the > > > original block by hash value, then moves the last half of the entries to > > > the new block - without accounting for how much space this actually moves. > > > (IOW, it moves half of the entry *count* not half of the entry *space*). > > > If by chance we have both large & small entries, and we move only the > > > smallest entries, and we have a large new entry to insert, we may not have > > > created enough space for it. > > > > (btw, the upshot of this is that in add_dirent_to_buf(), > > memcpy(de->name, name, namelen) will overshoot the buffer and actually > > corrupt memory.) > > So this looks like 2.6.22 and 2.6.23 material, but the timing is getting > pretty squeezy. Could people please give this change an extra-close > review, let me know? I already discussed it at length with Eric and inspected the patch, so we could add: Signed-off-by: Andreas Dilger Haven't actually tested the code myself. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.