Re: [patch][rfc] mm: new address space calls

[Nick Piggin <npiggin@suse.de>]

On Sat, Feb 28, 2009 at 06:19:56PM -0500, Christoph Hellwig wrote:
> On Wed, Feb 25, 2009 at 03:59:57PM -0500, Chris Mason wrote:
> > One problem I have with the btrfs extent state code is that I might
> > choose to release the extent state in releasepage, but the VM might not
> > choose to free the page.  So I've got an up to date page without any of
> > the rest of my state.
> > 
> > Which of these ops covers that? ;)  I'd love to help better document the
> > requirements for these callbacks, I find it confusing every time.
> 
> releasepage has also another problem.  It only gets called after
> discard_buffer discarded lots of valuable information from the buffers,
> which gets XFS into really bad trouble as that drops information if
> there is a delalloc extent.

Then I think it just needs to provide its own invalidatepage?


> I'd really like to see some major overhaul in that area, and that also
> extende to documentation (or just naming, why is block_invalidatepage
> calling into a method called ->releasepage, but there also is a
> ->invalidatepage that gets called from truncate*page routines..)

Those convoluted call paths are really bloody annoying.