backing_dev_info cleanups & lifetime rule fixes V2

[Christoph Hellwig]

On Sun, Feb 01, 2015 at 06:31:16AM +0000, Al Viro wrote:
> And at that point we finally can make sb_lock and super_blocks static in
> fs/super.c.  Do you want that in your tree, or would you rather have it
> done via vfs.git during the merge window after your tree goes in?  It's
> as trivial as this:
> 
> Make super_blocks and sb_lock static
> 
> The only user outside of fs/super.c is gone now
> 
> Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>

I'd say merge it through the block tree..

Acked-by: Christoph Hellwig <hch at lst.de>