Re: [Ext2-devel] Re: Reviewing ext3 improvement patches (delalloc, mballoc, extents)

[Andreas Dilger <adilger@clusterfs.com>]

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On Mar 04, 2005  15:29 +0300, Alex Tomas wrote:
> On Fri, 4 Mar 2005 16:43:31 +0530
> Suparna Bhattacharya <suparna@in.ibm.com> wrote:
> 
> > Alex, have you had a chance to prototype your idea of rooting extents
> > in ea ?
> 
> I think all you need for this are:
> 
> 1) allocate EA in ext3_new_inode()
> 2) write a replacement for ext3_init_tree_desc()
>    just few lines of code
> 3) write .get_write_access and .mark_buffer_dirty methods
>    again few lines
> 4) use replacement of ext3_init_tree_desc() in few places

This should of course only be done for large inodes.  Also, at some
point it will consume all of the EA space and we need to use an
external block.  It might help in some middle cases (i.e. files with
more extents than can fit in i_blocks (60 bytes), but less than fit
into the large inode space (128 or maybe 384 bytes)) but it might
also hurt other things if we need to allocate an EA block for another
EA...

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://members.shaw.ca/adilger/             http://members.shaw.ca/golinux/


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