btrfs_block_rsv_add_bytes
btrfs_block_rsv_add_bytes(dst, num_bytes, update_size);
btrfs_block_rsv_add_bytes(block_rsv, num_bytes, true);
btrfs_block_rsv_add_bytes(block_rsv, num_bytes, false);
btrfs_block_rsv_add_bytes(block_rsv, blocksize, false);
void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
btrfs_block_rsv_add_bytes(block_rsv, meta_reserve, false);
btrfs_block_rsv_add_bytes(trans_rsv, num_bytes, true);
btrfs_block_rsv_add_bytes(&h->delayed_rsv, delayed_refs_bytes, true);