[Sheepdog] [PATCH v3 2/2] sheep: abstract out store IO interface

[Liu Yuan]

On 11/17/2011 06:27 PM, MORITA Kazutaka wrote:

> I think this is still not generic...  If this is specific one to
> simple_store, move it to simple_store.c.
> 
>


I use siocb for interface functions internal information passing *and*
for higher level code to specify flags, length, buf, offset to store.rw
too.

This is just a dirty hack, enabling me to make small changes to the
previous code to work with simple store correctly.

My intention is that siocb is not specific to simple store. we need a
channel to send information to store.open(), then it can use it
communicate with store.read/write/close.

So I think siocb would be globally seen by higher level code.

if we don't use siocb, then what do you suggest to use for higher level
information (for e.g, flags, length, buf, offset) to store's interfaces?

We can't simple pass a void *ptr, without knowing the internal structure
for it.

and even if later, siocb get changed, we don't need to change current
(oid, void *priv) interface.

This is my own thought, maybe there is better idea.


> Remove the 'static' modifier in store.c if you want to use obj_path in
> this file.
> 


Umm, obj_path is not static in my repo...I guess some patch remove it
already. I'll rebase it.


>> +			ret = store_write_last_sector(oid, &fd);
> 
> store_write_last_sector() expects struct siocb in the second argument.
> 


Good catch, it is my carelessness.

> 
> I think we should define opaque as 'void *', get a store_driver
> specific opaque in the argument of store.open(), and pass it to
> store.read()/write()/close().  This is also what Christoph suggested.
> Am i wrong?
>


Like above, so it is totally opaque, where can we pass flags, length,
offset to store driver?

Thanks,
Yuan