[PATCH v3 3/6] mm/hugetlb: add hugetlb_folio_subpool() helper

[Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>]

Allows hugetlbfs_migrate_folio to check subpool information by passing
in a folio.

Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
(cherry picked from commit cd9e187858b45b890097cfcd0b2eb4bbbb9a59ae)
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
---
 fs/hugetlbfs/inode.c    | 4 ++--
 include/linux/hugetlb.h | 7 ++++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 52d9b390389b..c2e9c0cdbd81 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1151,9 +1151,9 @@ static int hugetlbfs_migrate_folio(struct address_space *mapping,
 	if (rc != MIGRATEPAGE_SUCCESS)
 		return rc;
 
-	if (hugetlb_page_subpool(&src->page)) {
+	if (hugetlb_folio_subpool(src)) {
 		hugetlb_set_page_subpool(&dst->page,
-					hugetlb_page_subpool(&src->page));
+					hugetlb_folio_subpool(src));
 		hugetlb_set_page_subpool(&src->page, NULL);
 	}
 
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 0952ea50251d..1e7c4007386e 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -744,12 +744,17 @@ extern unsigned int default_hstate_idx;
 
 #define default_hstate (hstates[default_hstate_idx])
 
+static inline struct hugepage_subpool *hugetlb_folio_subpool(struct folio *folio)
+{
+	return (void *)folio_get_private_1(folio);
+}
+
 /*
  * hugetlb page subpool pointer located in hpage[1].private
  */
 static inline struct hugepage_subpool *hugetlb_page_subpool(struct page *hpage)
 {
-	return (void *)page_private(hpage + SUBPAGE_INDEX_SUBPOOL);
+	return hugetlb_folio_subpool(page_folio(hpage));
 }
 
 static inline void hugetlb_set_page_subpool(struct page *hpage,
-- 
2.31.1