504,505c504,512
< 		/* compute read ahead block number */
< 		rabn = imap(ip, (offset+BSIZE)>>BSHIFT, READ);
---
> 		/* find length of contiguous read and compute read ahead block */
> 		rabn = bn;
> 		i = 1;
> 		do {
> 			if((rabn = imap(ip, (offset>>BSHIFT) + i, READ) != bn + i)
> 				break;
> 		}  while(n + (++i<<BSHIFT) <= count);
> 		n = min(n + (i<<BSHIFT), count);
>