Re: [2.6 patch] mm/swap_state.c: unexport swapper_space

[Hugh Dickins <hugh@veritas.com>]

On Sun, 6 Mar 2005, Adrian Bunk wrote:

> I didn't find any possible modular usage in the kernel.
> 
> Signed-off-by: Adrian Bunk <bunk@stusta.de>
> 
> --- linux-2.6.11-mm1-full/mm/swap_state.c.old	2005-03-04 16:25:54.000000000 +0100
> +++ linux-2.6.11-mm1-full/mm/swap_state.c	2005-03-04 16:26:16.000000000 +0100
> @@ -40,7 +40,6 @@
>  	.i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
>  	.backing_dev_info = &swap_backing_dev_info,
>  };
> -EXPORT_SYMBOL(swapper_space);
>  
>  #define INC_CACHE_INFO(x)	do { swap_cache_info.x++; } while (0)

I think this one should stay exported (or at least be re-exported
immediately on demand).  It's used by the inline page_mapping() in
include/linux/mm.h, which _was_ used by various arch cacheflushing
inlines, which could reasonably be called from modular filesystems.

I think those architectures hit the missed export when the dependence
on &swapper_space got added to page_mapping(), the export was soon
added to mainline, but meanwhile they moved their inlines out-of-line
- perhaps temporarily, but not yet reverted.

Better leave it exported so long as page_mapping is using it.

Hugh