Re: [PATCH take2 1/5] dio: centralize completion in dio_complete()

[Zach Brown <zach.brown@oracle.com>]

>> -static void dio_complete(struct dio *dio, loff_t offset, ssize_t bytes)
>> +static int dio_complete(struct dio *dio, loff_t offset, int ret)
>>  {
>> +	ssize_t transferred = 0;
>> +
>> +	if (dio->result) {
>> +		transferred = dio->result;
>> +
>> +		/* Check for short read case */
>> +		if ((dio->rw == READ) && ((offset + transferred) > dio->i_size))
>> +			transferred = dio->i_size - offset;
> 
> On 32-bit machines ssize_t is `int' and loff_t is `long long'.  I guess
> `transferred' cannot overflow because you can't write >4G.  And I guess
> `transferred' cannot go negative because you cannot write >=2G.  Can you
> confirm that thinking?

Well, I think this ssize_t mirrors the return types for the read and
write syscalls and match the ssize_t wrapping checks on input by
rw_verify_area() and do_readv_writev().  I *think* that covers it,
though I haven't really audited all the ways to get to this code.

- z