[PATCH] block: convert tasklets to use new tasklet_setup() API

[Allen]

> [...]
> > > Since both threads seem to have petered out, let me suggest in
> > > kernel.h:
> > >
> > > #define cast_out(ptr, container, member) \
> > >     container_of(ptr, typeof(*container), member)
> > >
> > > It does what you want, the argument order is the same as
> > > container_of with the only difference being you name the containing
> > > structure instead of having to specify its type.
> >
> > Not to incessantly bike shed on the naming, but I don't like
> > cast_out, it's not very descriptive. And it has connotations of
> > getting rid of something, which isn't really true.
>
> Um, I thought it was exactly descriptive: you're casting to the outer
> container.  I thought about following the C++ dynamic casting style, so
> out_cast(), but that seemed a bit pejorative.  What about outer_cast()?
>
> > FWIW, I like the from_ part of the original naming, as it has some
> > clues as to what is being done here. Why not just from_container()?
> > That should immediately tell people what it does without having to
> > look up the implementation, even before this becomes a part of the
> > accepted coding norm.
>
> I'm not opposed to container_from() but it seems a little less
> descriptive than outer_cast() but I don't really care.  I always have
> to look up container_of() when I'm using it so this would just be
> another macro of that type ...
>

 So far we have a few which have been suggested as replacement
for from_tasklet()

- out_cast() or outer_cast()
- from_member().
- container_from() or from_container()

from_container() sounds fine, would trimming it a bit work? like from_cont().

-- 
       - Allen