f2fs: provide f2fs_balance_fs to __write_node_page

Let node writeback also do f2fs_balance_fs to ensure there are always enough free
segments.

Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -1017,7 +1017,7 @@ retry_flush_nodes:
 
 	if (get_pages(sbi, F2FS_DIRTY_NODES)) {
 		up_write(&sbi->node_write);
-		err = sync_node_pages(sbi, &wbc);
+		err = sync_node_pages(sbi, &wbc, false);
 		if (err) {
 			up_write(&sbi->node_change);
 			f2fs_unlock_all(sbi);

fs/f2fs/f2fs.h

@@ -2390,7 +2390,8 @@ struct page *get_node_page_ra(struct page *parent, int start);
 void move_node_page(struct page *node_page, int gc_type);
 int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 			struct writeback_control *wbc, bool atomic);
-int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc);
+int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc,
+			bool do_balance);
 void build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount);
 bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid);
 void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid);

fs/f2fs/node.c

@@ -1327,7 +1327,7 @@ continue_unlock:
 }
 
 static int __write_node_page(struct page *page, bool atomic, bool *submitted,
-				struct writeback_control *wbc)
+				struct writeback_control *wbc, bool do_balance)
 {
 	struct f2fs_sb_info *sbi = F2FS_P_SB(page);
 	nid_t nid;
@@ -1396,6 +1396,8 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
 	if (submitted)
 		*submitted = fio.submitted;
 
+	if (do_balance)
+		f2fs_balance_fs(sbi, false);
 	return 0;
 
 redirty_out:
@@ -1406,7 +1408,7 @@ redirty_out:
 static int f2fs_write_node_page(struct page *page,
 				struct writeback_control *wbc)
 {
-	return __write_node_page(page, false, NULL, wbc);
+	return __write_node_page(page, false, NULL, wbc, false);
 }
 
 int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
@@ -1494,7 +1496,7 @@ continue_unlock:
 
 			ret = __write_node_page(page, atomic &&
 						page == last_page,
-						&submitted, wbc);
+						&submitted, wbc, true);
 			if (ret) {
 				unlock_page(page);
 				f2fs_put_page(last_page, 0);
@@ -1531,7 +1533,8 @@ out:
 	return ret ? -EIO: 0;
 }
 
-int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc)
+int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc,
+							bool do_balance)
 {
 	pgoff_t index, end;
 	struct pagevec pvec;
@@ -1609,7 +1612,8 @@ continue_unlock:
 			set_fsync_mark(page, 0);
 			set_dentry_mark(page, 0);
 
-			ret = __write_node_page(page, false, &submitted, wbc);
+			ret = __write_node_page(page, false, &submitted,
+							wbc, do_balance);
 			if (ret)
 				unlock_page(page);
 			else if (submitted)
@@ -1698,7 +1702,7 @@ static int f2fs_write_node_pages(struct address_space *mapping,
 	diff = nr_pages_to_write(sbi, NODE, wbc);
 	wbc->sync_mode = WB_SYNC_NONE;
 	blk_start_plug(&plug);
-	sync_node_pages(sbi, wbc);
+	sync_node_pages(sbi, wbc, true);
 	blk_finish_plug(&plug);
 	wbc->nr_to_write = max((long)0, wbc->nr_to_write - diff);
 	return 0;