mm/khugepaged: use a folio more in collapse_file()

This function is not yet fully converted to the folio API, but this
removes a few uses of old APIs.

Link: https://lkml.kernel.org/r/20231228085748.1083901-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Matthew Wilcox (Oracle)

mm/khugepaged.c

@@ -2122,23 +2122,23 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 		xas_lock_irq(&xas);
 	}
 
-	nr = thp_nr_pages(hpage);
+	folio = page_folio(hpage);
+	nr = folio_nr_pages(folio);
 	if (is_shmem)
-		__mod_lruvec_page_state(hpage, NR_SHMEM_THPS, nr);
+		__lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr);
 	else
-		__mod_lruvec_page_state(hpage, NR_FILE_THPS, nr);
+		__lruvec_stat_mod_folio(folio, NR_FILE_THPS, nr);
 
 	if (nr_none) {
-		__mod_lruvec_page_state(hpage, NR_FILE_PAGES, nr_none);
+		__lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr_none);
 		/* nr_none is always 0 for non-shmem. */
-		__mod_lruvec_page_state(hpage, NR_SHMEM, nr_none);
+		__lruvec_stat_mod_folio(folio, NR_SHMEM, nr_none);
 	}
 
 	/*
 	 * Mark hpage as uptodate before inserting it into the page cache so
 	 * that it isn't mistaken for an fallocated but unwritten page.
 	 */
-	folio = page_folio(hpage);
 	folio_mark_uptodate(folio);
 	folio_ref_add(folio, HPAGE_PMD_NR - 1);
 
@@ -2148,7 +2148,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 
 	/* Join all the small entries into a single multi-index entry. */
 	xas_set_order(&xas, start, HPAGE_PMD_ORDER);
-	xas_store(&xas, hpage);
+	xas_store(&xas, folio);
 	WARN_ON_ONCE(xas_error(&xas));
 	xas_unlock_irq(&xas);
 
@@ -2159,7 +2159,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 	retract_page_tables(mapping, start);
 	if (cc && !cc->is_khugepaged)
 		result = SCAN_PTE_MAPPED_HUGEPAGE;
-	unlock_page(hpage);
+	folio_unlock(folio);
 
 	/*
 	 * The collapse has succeeded, so free the old pages.