Date: Mon, 17 Sep 2007 13:30:20 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Eric Sandeen <sandeen@sandeen.net>
Cc: Eric Sandeen <sandeen@redhat.com>,
       ext4 development <linux-ext4@vger.kernel.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       hooanon05@yahoo.co.jp, "Theodore Ts'o" <tytso@mit.edu>
Subject: Re: [PATCH] ext34: ensure do_split leaves enough free space in both
 blocks
Message-Id: <20070917133020.5fc4650c.akpm@linux-foundation.org>
In-Reply-To: <46EEB7A4.9040903@sandeen.net>
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	<46EEB7A4.9040903@sandeen.net>
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On Mon, 17 Sep 2007 12:21:40 -0500
Eric Sandeen <sandeen@sandeen.net> wrote:

> 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.)

Nice!

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?

Thanks.
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