Re: [00/17] Large Blocksize Support V3

From: Christoph Lameter
Date: Thu Apr 26 2007 - 02:41:03 EST

On Thu, 26 Apr 2007, Nick Piggin wrote:

> > The page cache has no problems supporting things with a block
> > size larger then page size. Now the block device layer may not
> > have the code to do the scatter gather into small pages and it
> > may not handle buffer heads whose data is split between multiple
> > pages.
> Yeah, this patch is not really large blocksize support (which we normally
> think of as block size > page cache size).

No? It depends on how you define block size. This patch definitely allows
a set blocksize function call with a size larger than 4k.

> > I suspect what needs to be fixed is the page cache block device
> > interface so that we have helper functions that know how to stuff
> > a single block into several pages.
> I am working now and again on some code to do this, it is a big job but
> I think it is the right way to do it. But it would take a long time to
> get stable and supported by filesystems...

Ummm... We already have a radix tree for this???? What more is needed? You
just need to go through all filesystems and make them use extends.

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