[PATCH v11 4/9] block: add check when merging zone device pages

[Chaitanya Kulkarni]

On 10/21/22 10:41, Logan Gunthorpe wrote:
> Consecutive zone device pages should not be merged into the same sgl
> or bvec segment with other types of pages or if they belong to different
> pgmaps. Otherwise getting the pgmap of a given segment is not possible
> without scanning the entire segment. This helper returns true either if
> both pages are not zone device pages or both pages are zone device
> pages with the same pgmap.
> 
> Add a helper to determine if zone device pages are mergeable and use
> this helper in page_is_mergeable().
> 
> Signed-off-by: Logan Gunthorpe <logang at deltatee.com>
> Reviewed-by: Christoph Hellwig <hch at lst.de>
> Reviewed-by: John Hubbard <jhubbard at nvidia.com>
> ---
>   block/bio.c            |  2 ++
>   include/linux/mmzone.h | 24 ++++++++++++++++++++++++
>   2 files changed, 26 insertions(+)
> 

Reviewed-by: Chaitanya Kulkarni <kch at nvidia.com>

-ck