provide more common DMA API functions V2

[Christoph Hellwig]

On Tue, Aug 18, 2015 at 09:51:07AM +0200, Ingo Molnar wrote:
> I.e. shouldn't this be:
> 
> > I'll merge these 5 patches for 4.4.  That means I'll release them into 
> > linux-next after 4.2 is released.
> >
> > [...]
> > 
> > Linus will be releasing 4.2 in 1-2 weeks and until then, linux-next is supposed 
> > to contain only 4.3 material.  Once 4.2 is released and the 4.3 merge window 
> > opens, linux-next is open for 4.4 material.
> 
> ?

That would make a lot more sense.  But also be said as I intended
these as the simple part of the dma work I'd like to get into 4.3.

Andrew, if you think it's not 4.3 material I'd rather keep them in
my git tree for now so that I can stack additional patches I have
in progress on top.  A non-git based tree like yours is unfortunately
very bad for patches that are dependencies for others.