mm: convert hugetlb_page_mapping_lock_write to folio

The page is only used to get the mapping, so the folio will do just as
well.  Both callers already have a folio available, so this saves a call
to compound_head().

Link: https://lkml.kernel.org/r/20240412193510.2356957-7-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jane Chu  <jane.chu@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/hugetlb.h

@@ -178,7 +178,7 @@ bool hugetlbfs_pagecache_present(struct hstate *h,
 				 struct vm_area_struct *vma,
 				 unsigned long address);
 
-struct address_space *hugetlb_page_mapping_lock_write(struct page *hpage);
+struct address_space *hugetlb_folio_mapping_lock_write(struct folio *folio);
 
 extern int sysctl_hugetlb_shm_group;
 extern struct list_head huge_boot_pages[MAX_NUMNODES];
@@ -297,8 +297,8 @@ static inline unsigned long hugetlb_total_pages(void)
 	return 0;
 }
 
-static inline struct address_space *hugetlb_page_mapping_lock_write(
-							struct page *hpage)
+static inline struct address_space *hugetlb_folio_mapping_lock_write(
+							struct folio *folio)
 {
 	return NULL;
 }

mm/hugetlb.c

@@ -2155,13 +2155,13 @@ static bool prep_compound_gigantic_folio_for_demote(struct folio *folio,
 /*
  * Find and lock address space (mapping) in write mode.
  *
- * Upon entry, the page is locked which means that page_mapping() is
+ * Upon entry, the folio is locked which means that folio_mapping() is
  * stable.  Due to locking order, we can only trylock_write.  If we can
  * not get the lock, simply return NULL to caller.
  */
-struct address_space *hugetlb_page_mapping_lock_write(struct page *hpage)
+struct address_space *hugetlb_folio_mapping_lock_write(struct folio *folio)
 {
-	struct address_space *mapping = page_mapping(hpage);
+	struct address_space *mapping = folio_mapping(folio);
 
 	if (!mapping)
 		return mapping;

mm/memory-failure.c

@@ -1624,7 +1624,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 		 * TTU_RMAP_LOCKED to indicate we have taken the lock
 		 * at this higher level.
 		 */
-		mapping = hugetlb_page_mapping_lock_write(hpage);
+		mapping = hugetlb_folio_mapping_lock_write(folio);
 		if (mapping) {
 			try_to_unmap(folio, ttu|TTU_RMAP_LOCKED);
 			i_mmap_unlock_write(mapping);

mm/migrate.c

@@ -1425,7 +1425,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 			 * semaphore in write mode here and set TTU_RMAP_LOCKED
 			 * to let lower levels know we have taken the lock.
 			 */
-			mapping = hugetlb_page_mapping_lock_write(&src->page);
+			mapping = hugetlb_folio_mapping_lock_write(src);
 			if (unlikely(!mapping))
 				goto unlock_put_anon;