Re: [PATCH 03/10] mm: Add support for a filesystem to control swapfiles

[Mel Gorman]

On Mon, Sep 12, 2011 at 11:04:45AM +0200, Peter Zijlstra wrote:
> On Fri, 2011-09-09 at 09:36 -0400, Christoph Hellwig wrote:
> > The equivalent of ->direct_IO should be used for both reads and writes.
> 
> So the difference between DIO and swapIO is that swapIO needs the block
> map pinned in memory.. So at the very least you'll need those
> swap_{activate,deactivate} aops. The read/write-page thingies could
> indeed be shared with DIO.
> 

I'm travelling at the moment so it'll be later in the week when I investigate
properly but I agree swap_[de|a]ctivate are still necessary. NFS does not
need to pin a block map but it's still necessary for calling xs_set_memalloc.

-- 
Mel Gorman
SUSE Labs
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