khugepage: replace try_to_release_page() with filemap_release_folio()

Replace some calls with their folio equivalents.  This change removes 4
calls to compound_head() and is in preparation for the removal of the
try_to_release_page() wrapper.

Link: https://lkml.kernel.org/r/20221118073055.55694-3-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged.c

@@ -1789,6 +1789,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 	xas_set(&xas, start);
 	for (index = start; index < end; index++) {
 		struct page *page = xas_next(&xas);
+		struct folio *folio;
 
 		VM_BUG_ON(index != xas.xa_index);
 		if (is_shmem) {
@@ -1815,8 +1816,6 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 			}
 
 			if (xa_is_value(page) || !PageUptodate(page)) {
-				struct folio *folio;
-
 				xas_unlock_irq(&xas);
 				/* swap in or instantiate fallocated page */
 				if (shmem_get_folio(mapping->host, index,
@@ -1904,13 +1903,15 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 			goto out_unlock;
 		}
 
-		if (page_mapping(page) != mapping) {
+		folio = page_folio(page);
+
+		if (folio_mapping(folio) != mapping) {
 			result = SCAN_TRUNCATED;
 			goto out_unlock;
 		}
 
-		if (!is_shmem && (PageDirty(page) ||
-				  PageWriteback(page))) {
+		if (!is_shmem && (folio_test_dirty(folio) ||
+				  folio_test_writeback(folio))) {
 			/*
 			 * khugepaged only works on read-only fd, so this
 			 * page is dirty because it hasn't been flushed
@@ -1920,20 +1921,20 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 			goto out_unlock;
 		}
 
-		if (isolate_lru_page(page)) {
+		if (folio_isolate_lru(folio)) {
 			result = SCAN_DEL_PAGE_LRU;
 			goto out_unlock;
 		}
 
-		if (page_has_private(page) &&
-		    !try_to_release_page(page, GFP_KERNEL)) {
+		if (folio_has_private(folio) &&
+		    !filemap_release_folio(folio, GFP_KERNEL)) {
 			result = SCAN_PAGE_HAS_PRIVATE;
-			putback_lru_page(page);
+			folio_putback_lru(folio);
 			goto out_unlock;
 		}
 
-		if (page_mapped(page))
-			try_to_unmap(page_folio(page),
+		if (folio_mapped(folio))
+			try_to_unmap(folio,
 					TTU_IGNORE_MLOCK | TTU_BATCH_FLUSH);
 
 		xas_lock_irq(&xas);