huge_memory: convert unmap_page() to unmap_folio()

Remove a folio->page->folio conversion.

Link: https://lkml.kernel.org/r/20220902194653.1739778-54-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/huge_memory.c

@@ -2355,13 +2355,12 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
 	}
 }
 
-static void unmap_page(struct page *page)
+static void unmap_folio(struct folio *folio)
 {
-	struct folio *folio = page_folio(page);
 	enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
 		TTU_SYNC;
 
-	VM_BUG_ON_PAGE(!PageHead(page), page);
+	VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
 
 	/*
 	 * Anon pages need migration entries to preserve them, but file
@@ -2378,7 +2377,7 @@ static void remap_page(struct folio *folio, unsigned long nr)
 {
 	int i = 0;
 
-	/* If unmap_page() uses try_to_migrate() on file, remove this check */
+	/* If unmap_folio() uses try_to_migrate() on file, remove this check */
 	if (!folio_test_anon(folio))
 		return;
 	for (;;) {
@@ -2428,7 +2427,7 @@ static void __split_huge_page_tail(struct page *head, int tail,
 	 * for example lock_page() which set PG_waiters.
 	 *
 	 * Note that for mapped sub-pages of an anonymous THP,
-	 * PG_anon_exclusive has been cleared in unmap_page() and is stored in
+	 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in
 	 * the migration entry instead from where remap_page() will restore it.
 	 * We can still have PG_anon_exclusive set on effectively unmapped and
 	 * unreferenced sub-pages of an anonymous THP: we can simply drop
@@ -2700,7 +2699,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	}
 
 	/*
-	 * Racy check if we can split the page, before unmap_page() will
+	 * Racy check if we can split the page, before unmap_folio() will
 	 * split PMDs
 	 */
 	if (!can_split_folio(folio, &extra_pins)) {
@@ -2708,7 +2707,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 		goto out_unlock;
 	}
 
-	unmap_page(&folio->page);
+	unmap_folio(folio);
 
 	/* block interrupt reentry in xa_lock and spinlock */
 	local_irq_disable();