i_nblks
xi->i_nblks = 0;
xi->i_nblks = xi->i_len >> shift;
xi->i_nblks = xi->i_len >> shift;
xi->i_nblks = xi->i_len >> shift;
xi->i_blkno += xi->i_nblks;
xi->i_nblks = len >> xi->i_blkshift;