On Sun, Aug 3, 2008 at 5:50 PM, rahul p <rahulpyd@xxxxxxxxx> wrote:
> Manish,
>
> It all looks pretty clear to me. In the first case the 'get_block_t'
> structure is passed as an argument to the function. In the other case the
> pointer to the structure (get_block_t*) is passed as a function argument. I
> hope you know the difference between the 2. If not the following link would
> help.
Hi Rahul,
I understand the diff between passing as argument and as pointer.
However see how it is used in the two function.
static struct bio * do_mpage_readpage(............., get_block_t get_block) {
...........
...........
if (get_block(inode, block_in_file, map_bh, 0))
goto confused;
.........
confused:
if (!PageUptodate(page))
block_read_full_page(page, get_block);
}
int block_read_full_page(struct page *page, get_block_t *get_block)
{
.............
.............
err = get_block(inode, iblock, bh, 0);
...........
}
Thanks -
Manish
>
> http://www2.its.strath.ac.uk/courses/c/subsection3_12_3.html#SECTION00012300000000000000
>
> -
> Rahul Pydimukkala
>
>
>
> On Sun, Aug 3, 2008 at 1:53 PM, Daniel Baluta <daniel.baluta@xxxxxxxxx>
> wrote:
>>
>> See the definition of get_block_t
>>
>> typedef int (get_block_t)(struct inode *inode, sector_t iblock,
>> struct buffer_head *bh_result, int create);
>>
>>
>>
>> On 8/3/08, Manish Katiyar <mkatiyar@xxxxxxxxx> wrote:
>> > ok... I know i am going to be embarrassed but I am confused by the
>> > below function. The last parameter in do_mpage_readpage() is of type
>> > get_block_t, but when passed to block_read_full_page() it gets passed
>> > as get_block_t *.
>> >
>> >
>> > static struct bio * do_mpage_readpage(............., get_block_t
>> > get_block)
>> > {
>> > ................
>> > ................
>> > if (page_has_buffers(page))
>> > goto confused;
>> > .................
>> > confused:
>> > if (!PageUptodate(page))
>> > block_read_full_page(page, get_block);
>> > .........
>> > }
>> >
>> > int block_read_full_page(struct page *page, get_block_t *get_block) {
>> > .........
>> > ..........
>> > }
>> >
>> >
>> > How does this work ? :-( ....... Isn't gcc supposed to catch this and
>> > flag warning unless I am missing something very obvious.
>> >
>> > Thanks -
>> > Manish
>> >
>> > --
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>> >
>> >
>>
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>
>
>
> --
> Smart data structures and dumb code works a lot better than the other way
> around. -Eric S Raymond
>
>
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