[PATCH v3 2/7] mm: memremap: add pgmap_parent_resource() helper

[Li Zhijian <lizhijian@fujitsu.com>]

It's a helper to set the parent resource for the altmap of a given pgmap

CC: Andrew Morton <akpm@linux-foundation.org>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Baoquan He <bhe@redhat.com>
CC: linux-mm@kvack.org
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
---
 include/linux/memremap.h | 1 +
 mm/memremap.c            | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index ca1f12353008..1e8b25352f7c 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -193,6 +193,7 @@ static inline bool folio_is_device_coherent(const struct folio *folio)
 void zone_device_page_init(struct page *page);
 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
 void memunmap_pages(struct dev_pagemap *pgmap);
+void pgmap_parent_resource(struct dev_pagemap *pgmap, struct resource *res);
 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
diff --git a/mm/memremap.c b/mm/memremap.c
index 78047157b0ee..0bbf163d4817 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -390,6 +390,13 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 }
 EXPORT_SYMBOL_GPL(memremap_pages);
 
+void pgmap_parent_resource(struct dev_pagemap *pgmap, struct resource *res)
+{
+	if (pgmap && res)
+		pgmap->altmap.parent = res;
+}
+EXPORT_SYMBOL_GPL(pgmap_parent_resource);
+
 /**
  * devm_memremap_pages - remap and provide memmap backing for the given resource
  * @dev: hosting device for @res
-- 
2.29.2