memory-failure: use a folio in me_huge_page()

This function was already explicitly calling compound_head();
unfortunately the compiler can't know that and elide the redundant calls
to compound_head() buried in page_mapping(), unlock_page(), etc.  Switch
to using a folio, which does let us elide these calls.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Matthew Wilcox (Oracle)

mm/memory-failure.c

@@ -1182,25 +1182,25 @@ static int me_swapcache_clean(struct page_state *ps, struct page *p)
  */
 static int me_huge_page(struct page_state *ps, struct page *p)
 {
+	struct folio *folio = page_folio(p);
 	int res;
-	struct page *hpage = compound_head(p);
 	struct address_space *mapping;
 	bool extra_pins = false;
 
-	mapping = page_mapping(hpage);
+	mapping = folio_mapping(folio);
 	if (mapping) {
-		res = truncate_error_page(hpage, page_to_pfn(p), mapping);
+		res = truncate_error_page(&folio->page, page_to_pfn(p), mapping);
 		/* The page is kept in page cache. */
 		extra_pins = true;
-		unlock_page(hpage);
+		folio_unlock(folio);
 	} else {
-		unlock_page(hpage);
+		folio_unlock(folio);
 		/*
 		 * migration entry prevents later access on error hugepage,
 		 * so we can free and dissolve it into buddy to save healthy
 		 * subpages.
 		 */
-		put_page(hpage);
+		folio_put(folio);
 		if (__page_handle_poison(p) >= 0) {
 			page_ref_inc(p);
 			res = MF_RECOVERED;