On 03/31/2009 01:15 PM, Andrew Morton wrote:
> On Tue, 31 Mar 2009 12:04:36 +0300 Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
>
>>>> +static int write_exec(struct page_collect *pcol)
>>>> +{
>>>> + struct exofs_i_info *oi = exofs_i(pcol->inode);
>>>> + struct osd_obj_id obj = {pcol->sbi->s_pid,
>>>> + pcol->inode->i_ino + EXOFS_OBJ_OFF};
>>>> + struct osd_request *or = NULL;
>>>> + struct page_collect *pcol_copy = NULL;
>>>> + loff_t i_start = pcol->pg_first << PAGE_CACHE_SHIFT;
>>> bug. On 32-bit this shift will overflow prior to getting promoted to
>>> 64-bit. Do:
>>>
>>> loff_t i_start = (loff_t)pcol->pg_first << PAGE_CACHE_SHIFT;
>>>
>> In that case I might make pcol->pg_first loff_t.
>
> That would work.
>
>> Why is inode->i_index not an loff_t then?
>
> hm, what's i_index?
>
sorry, I meant page index
>> Page-index <=> byte-offset, is done all the time 12 bits does not
>> make a difference.
>
> Page indices are 32-bit on 32-bit CPUs. File offsets are 64-bit. We
> are careful to avoid the above overflow bug whenever the conversion
> from page index to file size is made. Try
>
> fgrep '(loff_t)' mm/*.c
>
right! which means that Linux does not support 64 bit offsets on
32 bit, but only 44 bits. But I guess exofs will not change that.
Boaz
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