EXFAT_CLU_TO_B
inode->i_blocks += EXFAT_CLU_TO_B(num_to_be_allocated, sbi) >> 9;
size = EXFAT_CLU_TO_B(p_dir->size, sbi);
i_size_write(inode, EXFAT_CLU_TO_B(root_clu->size, sbi));