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HTree in ext2 / ext3

Posted by herlock 
HTree in ext2 / ext3
February 07, 2010 03:07PM
I am a Belgian student in computer sciences at the Free University of Brussels ( ULB ).

I am currently working on a little article. I would like to explain the differences between ext2, ext3 and ext4.

During my researches, I read that ext2's directories are implemented with a linked-list structure. I also read Daniel Phillips's article from 2002 "A Directory index for ext2" and I'm a bit troubled.

Indeed, I see that the HTree data structure was developed for ext2 but I cannot see anywhere that the current ext2 implementation uses that data structure.

I opened the dir.c file from ext2 on the last stable kernel sources and I do not see anything about HTree, but the dir.c file from ext3 uses it, if I do not go wrong.

Could you explain me why people talk about "index directories for ext2" but there's no ext2 implementation that uses the HTree structure ? Is it only for ext3 ? Since when ? Could you give me some source that explain when was implemented HTree in ext{2,3} ?

Thanks a lot !
Re: HTree in ext2 / ext3
February 09, 2010 03:48AM
Questions solved. Andreas Dilger responsed me by mail that it was developed for ext2 but included in ext3.
Re: HTree in ext2 / ext3
May 20, 2010 11:27PM
I got the same confused with the htree implementation in ext2/3.
I only googled a news from lwn (http://lwn.net/Articles/11481/) that
ext3 seems did not include htree in 2002.
what i shot it that ext2 is for old usage and have no reason to include htree.
the one what to use ext2 can mkfs the dev with the pure old ext2 style.

Edited 2 time(s). Last edit at 05/21/2010 01:12AM by tonykou.

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