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Message-ID: <44A417A3.80001@google.com>
Date: Thu, 29 Jun 2006 11:10:43 -0700
From: Daniel Phillips <phillips@google.com>
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To: Andreas Dilger <adilger@clusterfs.com>
CC: Johann Lombardi <johann.lombardi@bull.net>, sho@tnes.nec.co.jp,
       cmm@us.ibm.com, ext2-devel@lists.sourceforge.net,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC 1/2] ext3: enlarge blocksize and fix rec_len overflow
References: <20060628205238sho@rifu.tnes.nec.co.jp> <20060628155048.GG2893@chiva> <20060628202421.GL5318@schatzie.adilger.int>
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Hi Andreas,

Andreas Dilger wrote:
> On Jun 28, 2006  17:50 +0200, Johann Lombardi wrote:
>>ext2/ext3_dir_entry_2 has a 16-bit entry(rec_len) and it would overflow
>>with 64KB blocksize.  This patch prevent from overflow by limiting
>>rec_len to 65532.
> 
> Having a max rec_len of 65532 is rather unfortunate, since the dir
> blocks always need to filled with dir entries.  65536 - 65532 = 4, and
> the minimum ext3_dir_entry size is 8 bytes.  I would instead make this
> maybe 64 bytes less so that there is room for a filename in the "tail"
> dir_entry.

Then why not introduce a little symmetry by making max rec_len 2**15 and
treat big directory blocks as an array of smaller ones?  I dimly recall
the page-cache oriented Ext2 dir code already does this.

Regards,

Daniel