-int btrfs_wait_on_page_writeback_range(struct address_space *mapping,
- pgoff_t start, pgoff_t end);
-int btrfs_fdatawrite_range(struct address_space *mapping, loff_t start,
- loff_t end, int sync_mode);
-int btrfs_wait_ordered_extents(struct btrfs_root *root, int nocow_only);