memory-failure: use a folio in me_pagecache_clean()

Patch series "Convert aops->error_remove_page to ->error_remove_folio".

This is a memory-failure patch series which converts a lot of uses of page
APIs into folio APIs with the usual benefits.  


This patch (of 6):

Replaces three hidden calls to compound_head() with one visible one.
Fix up a few comments while I'm modifying this function.

Link: https://lkml.kernel.org/r/20231117161447.2461643-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231117161447.2461643-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c

@@ -1014,6 +1014,7 @@ static int me_unknown(struct page_state *ps, struct page *p)
  */
 static int me_pagecache_clean(struct page_state *ps, struct page *p)
 {
+	struct folio *folio = page_folio(p);
 	int ret;
 	struct address_space *mapping;
 	bool extra_pins;
@@ -1021,10 +1022,10 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
 	delete_from_lru_cache(p);
 
 	/*
-	 * For anonymous pages we're done the only reference left
+	 * For anonymous folios the only reference left
 	 * should be the one m_f() holds.
 	 */
-	if (PageAnon(p)) {
+	if (folio_test_anon(folio)) {
 		ret = MF_RECOVERED;
 		goto out;
 	}
@@ -1036,11 +1037,9 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
 	 * has a reference, because it could be file system metadata
 	 * and that's not safe to truncate.
 	 */
-	mapping = page_mapping(p);
+	mapping = folio_mapping(folio);
 	if (!mapping) {
-		/*
-		 * Page has been teared down in the meanwhile
-		 */
+		/* Folio has been torn down in the meantime */
 		ret = MF_FAILED;
 		goto out;
 	}
@@ -1061,7 +1060,7 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
 		ret = MF_FAILED;
 
 out:
-	unlock_page(p);
+	folio_unlock(folio);
 
 	return ret;
 }