mm: convert page_get_anon_vma() to folio_get_anon_vma()

With all callers now passing in a folio, rename the function and convert
all callers.  Removes a couple of calls to compound_head() and a reference
to page->mapping.

Link: https://lkml.kernel.org/r/20220902194653.1739778-55-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/rmap.h

@@ -163,7 +163,7 @@ static inline void anon_vma_merge(struct vm_area_struct *vma,
 	unlink_anon_vmas(next);
 }
 
-struct anon_vma *page_get_anon_vma(struct page *page);
+struct anon_vma *folio_get_anon_vma(struct folio *folio);
 
 /* RMAP flags, currently only relevant for some anon rmap operations. */
 typedef int __bitwise rmap_t;

mm/huge_memory.c

@@ -2649,7 +2649,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 		 * is taken to serialise against parallel split or collapse
 		 * operations.
 		 */
-		anon_vma = page_get_anon_vma(&folio->page);
+		anon_vma = folio_get_anon_vma(folio);
 		if (!anon_vma) {
 			ret = -EBUSY;
 			goto out;

mm/migrate.c

@@ -1052,14 +1052,14 @@ static int __unmap_and_move(struct folio *src, struct folio *dst,
 	 * File Caches may use write_page() or lock_page() in migration, then,
 	 * just care Anon page here.
 	 *
-	 * Only page_get_anon_vma() understands the subtleties of
+	 * Only folio_get_anon_vma() understands the subtleties of
 	 * getting a hold on an anon_vma from outside one of its mms.
 	 * But if we cannot get anon_vma, then we won't need it anyway,
 	 * because that implies that the anon page is no longer mapped
 	 * (and cannot be remapped so long as we hold the page lock).
 	 */
 	if (folio_test_anon(src) && !folio_test_ksm(src))
-		anon_vma = page_get_anon_vma(&src->page);
+		anon_vma = folio_get_anon_vma(src);
 
 	/*
 	 * Block others from accessing the new page when we get around to
@@ -1298,7 +1298,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	}
 
 	if (folio_test_anon(src))
-		anon_vma = page_get_anon_vma(&src->page);
+		anon_vma = folio_get_anon_vma(src);
 
 	if (unlikely(!folio_trylock(dst)))
 		goto put_anon;

mm/rmap.c

@@ -486,16 +486,16 @@ void __init anon_vma_init(void)
  * if there is a mapcount, we can dereference the anon_vma after observing
  * those.
  */
-struct anon_vma *page_get_anon_vma(struct page *page)
+struct anon_vma *folio_get_anon_vma(struct folio *folio)
 {
 	struct anon_vma *anon_vma = NULL;
 	unsigned long anon_mapping;
 
 	rcu_read_lock();
-	anon_mapping = (unsigned long)READ_ONCE(page->mapping);
+	anon_mapping = (unsigned long)READ_ONCE(folio->mapping);
 	if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
 		goto out;
-	if (!page_mapped(page))
+	if (!folio_mapped(folio))
 		goto out;
 
 	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
@@ -505,13 +505,13 @@ struct anon_vma *page_get_anon_vma(struct page *page)
 	}
 
 	/*
-	 * If this page is still mapped, then its anon_vma cannot have been
+	 * If this folio is still mapped, then its anon_vma cannot have been
 	 * freed.  But if it has been unmapped, we have no security against the
 	 * anon_vma structure being freed and reused (for another anon_vma:
 	 * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
 	 * above cannot corrupt).
 	 */
-	if (!page_mapped(page)) {
+	if (!folio_mapped(folio)) {
 		rcu_read_unlock();
 		put_anon_vma(anon_vma);
 		return NULL;
@@ -523,11 +523,11 @@ struct anon_vma *page_get_anon_vma(struct page *page)
 }
 
 /*
- * Similar to page_get_anon_vma() except it locks the anon_vma.
+ * Similar to folio_get_anon_vma() except it locks the anon_vma.
  *
  * Its a little more complex as it tries to keep the fast path to a single
  * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
- * reference like with page_get_anon_vma() and then block on the mutex
+ * reference like with folio_get_anon_vma() and then block on the mutex
  * on !rwc->try_lock case.
  */
 struct anon_vma *folio_lock_anon_vma_read(struct folio *folio,