filemap: convert __filemap_fdatawait_range() to use filemap_get_folios_tag()

Convert function to use folios.  This is in preparation for the removal of
find_get_pages_range_tag().  This change removes 2 calls to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-4-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcow (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/filemap.c

@@ -503,25 +503,27 @@ static void __filemap_fdatawait_range(struct address_space *mapping,
 {
 	pgoff_t index = start_byte >> PAGE_SHIFT;
 	pgoff_t end = end_byte >> PAGE_SHIFT;
-	struct pagevec pvec;
-	int nr_pages;
+	struct folio_batch fbatch;
+	unsigned nr_folios;
+
+	folio_batch_init(&fbatch);
 
-	pagevec_init(&pvec);
 	while (index <= end) {
 		unsigned i;
 
-		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index,
-				end, PAGECACHE_TAG_WRITEBACK);
-		if (!nr_pages)
+		nr_folios = filemap_get_folios_tag(mapping, &index, end,
+				PAGECACHE_TAG_WRITEBACK, &fbatch);
+
+		if (!nr_folios)
 			break;
 
-		for (i = 0; i < nr_pages; i++) {
-			struct page *page = pvec.pages[i];
+		for (i = 0; i < nr_folios; i++) {
+			struct folio *folio = fbatch.folios[i];
 
-			wait_on_page_writeback(page);
-			ClearPageError(page);
+			folio_wait_writeback(folio);
+			folio_clear_error(folio);
 		}
-		pagevec_release(&pvec);
+		folio_batch_release(&fbatch);
 		cond_resched();
 	}
 }