merge struct block_device and struct hd_struct v4

[Christoph Hellwig]

On Sat, Nov 28, 2020 at 05:14:25PM +0100, Christoph Hellwig wrote:
> A git tree is available here:
> 
>     git://git.infradead.org/users/hch/block.git bdev-lookup
> 
> Gitweb:
> 
>     http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/bdev-lookup

I've updated the git tree with the set_capacity_and_notify change
suggested by Jan, a commit log typo fix and the Reviewed-by tags.

Jens, can you take a look and potentially merge the branch?  That would
really help with some of the pending work.