f2fs: unlock_page when node page is redirtied out

This patch fixes missing unlock_page when a node page is redirtied out.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/node.c

@@ -1129,8 +1129,11 @@ int sync_node_pages(struct f2fs_sb_info *sbi, nid_t ino,
 				set_fsync_mark(page, 0);
 				set_dentry_mark(page, 0);
 			}
-			NODE_MAPPING(sbi)->a_ops->writepage(page, wbc);
-			wrote++;
+
+			if (NODE_MAPPING(sbi)->a_ops->writepage(page, wbc))
+				unlock_page(page);
+			else
+				wrote++;
 
 			if (--wbc->nr_to_write == 0)
 				break;