[PATCH 2/6] mm: Constify page_address_in_vma()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

If we also mark the struct folio argument to folio_anon_vma(),
we can make page_address_in_vma() take a const struct page pointer.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/rmap.h | 2 +-
 mm/internal.h        | 2 +-
 mm/rmap.c            | 5 +++--
 mm/util.c            | 2 +-
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 0978c64f49d8..d1fca5b76039 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -732,7 +732,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
 /*
  * Used by swapoff to help locate where page is expected in vma.
  */
-unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
+unsigned long page_address_in_vma(const struct page *, struct vm_area_struct *);
 
 /*
  * Cleans the PTEs of shared mappings.
diff --git a/mm/internal.h b/mm/internal.h
index b4d86436565b..e511708b2be0 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -810,7 +810,7 @@ static inline bool is_data_mapping(vm_flags_t flags)
 }
 
 /* mm/util.c */
-struct anon_vma *folio_anon_vma(struct folio *folio);
+struct anon_vma *folio_anon_vma(const struct folio *folio);
 
 #ifdef CONFIG_MMU
 void unmap_mapping_folio(struct folio *folio);
diff --git a/mm/rmap.c b/mm/rmap.c
index 8616308610b9..886bf67ba382 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -771,9 +771,10 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
  * At what user virtual address is page expected in vma?
  * Caller should check the page is actually part of the vma.
  */
-unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
+unsigned long page_address_in_vma(const struct page *page,
+		struct vm_area_struct *vma)
 {
-	struct folio *folio = page_folio(page);
+	const struct folio *folio = page_folio(page);
 	pgoff_t pgoff;
 
 	if (folio_test_anon(folio)) {
diff --git a/mm/util.c b/mm/util.c
index bc488f0121a7..8afe3b90d650 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -780,7 +780,7 @@ void *vcalloc_noprof(size_t n, size_t size)
 }
 EXPORT_SYMBOL(vcalloc_noprof);
 
-struct anon_vma *folio_anon_vma(struct folio *folio)
+struct anon_vma *folio_anon_vma(const struct folio *folio)
 {
 	unsigned long mapping = (unsigned long)folio->mapping;
 
-- 
2.43.0