nilfs2: convert nilfs_segctor_prepare_write to use folios

Use the new folio APIs, saving 17 hidden calls to compound_head().

Link: https://lkml.kernel.org/r/20231114084436.2755-11-konishi.ryusuke@gmail.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/segment.c

@@ -1665,39 +1665,39 @@ static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
 	return 0;
 }
 
-static void nilfs_begin_page_io(struct page *page)
+static void nilfs_begin_folio_io(struct folio *folio)
 {
-	if (!page || PageWriteback(page))
+	if (!folio || folio_test_writeback(folio))
 		/*
 		 * For split b-tree node pages, this function may be called
 		 * twice.  We ignore the 2nd or later calls by this check.
 		 */
 		return;
 
-	lock_page(page);
-	clear_page_dirty_for_io(page);
-	set_page_writeback(page);
-	unlock_page(page);
+	folio_lock(folio);
+	folio_clear_dirty_for_io(folio);
+	folio_start_writeback(folio);
+	folio_unlock(folio);
 }
 
 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
 {
 	struct nilfs_segment_buffer *segbuf;
-	struct page *bd_page = NULL, *fs_page = NULL;
+	struct folio *bd_folio = NULL, *fs_folio = NULL;
 
 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
 		struct buffer_head *bh;
 
 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
 				    b_assoc_buffers) {
-			if (bh->b_page != bd_page) {
-				if (bd_page) {
-					lock_page(bd_page);
-					clear_page_dirty_for_io(bd_page);
-					set_page_writeback(bd_page);
-					unlock_page(bd_page);
+			if (bh->b_folio != bd_folio) {
+				if (bd_folio) {
+					folio_lock(bd_folio);
+					folio_clear_dirty_for_io(bd_folio);
+					folio_start_writeback(bd_folio);
+					folio_unlock(bd_folio);
 				}
-				bd_page = bh->b_page;
+				bd_folio = bh->b_folio;
 			}
 		}
 
@@ -1705,28 +1705,28 @@ static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
 				    b_assoc_buffers) {
 			set_buffer_async_write(bh);
 			if (bh == segbuf->sb_super_root) {
-				if (bh->b_page != bd_page) {
-					lock_page(bd_page);
-					clear_page_dirty_for_io(bd_page);
-					set_page_writeback(bd_page);
-					unlock_page(bd_page);
-					bd_page = bh->b_page;
+				if (bh->b_folio != bd_folio) {
+					folio_lock(bd_folio);
+					folio_clear_dirty_for_io(bd_folio);
+					folio_start_writeback(bd_folio);
+					folio_unlock(bd_folio);
+					bd_folio = bh->b_folio;
 				}
 				break;
 			}
-			if (bh->b_page != fs_page) {
-				nilfs_begin_page_io(fs_page);
-				fs_page = bh->b_page;
+			if (bh->b_folio != fs_folio) {
+				nilfs_begin_folio_io(fs_folio);
+				fs_folio = bh->b_folio;
 			}
 		}
 	}
-	if (bd_page) {
-		lock_page(bd_page);
-		clear_page_dirty_for_io(bd_page);
-		set_page_writeback(bd_page);
-		unlock_page(bd_page);
+	if (bd_folio) {
+		folio_lock(bd_folio);
+		folio_clear_dirty_for_io(bd_folio);
+		folio_start_writeback(bd_folio);
+		folio_unlock(bd_folio);
 	}
-	nilfs_begin_page_io(fs_page);
+	nilfs_begin_folio_io(fs_folio);
 }
 
 static int nilfs_segctor_write(struct nilfs_sc_info *sci,