PFS from INODZ

Pool is the device over which the file system is going to operate on. So, The pool has to redirect the requests that it gets to the original devices below it. I was bit stuck with "how can this communication be achieved ?"................
I was thinking of EXPORTING the transfer functions globally, so that, the pool's job as simple as to call the transfer functions. But is this generic ?
* I've EXPORT them.,
* Recompile the driver
* Also, you cant do this for all the drivers

COMPLETELY NOT GENERIC!

Then, Hari Helped!!!!!

He told me there are several ways by which u can achieve this without EXPORTING. one of the way is submit_bio(). I read in LDD3, "If you want to redirect, you change the bio->bi_bdev, and resubmit the bio".... [ GREAT!!! ]
But how to get the block_device object of a device....??

Hari Helped!!!!!

* Path_lookup the device
* Get the inode of the device from nameidata
* Get the dev_t object fom the inode
* open_by_devnum and get the block_device [GREAT!!!!]

ok... Got the block_device....
I changed the block_device and submited the bio
KERNEL PANICS!!!!!!!
tried tried tried tried tried....... 3 days of trying,
Hari pointed out the bug was there in bio_endio, but i din know what exactly the bug is.
05-01-2008, about 4.30 pm, evrery thing got so clear....

what i thought was,
* submit_bio() returns only after performing the whole I/O operation.
* so after the submit_bio, the bio is a waste
* i killed it after submit_bio

But the thing is,
* submit_bio retuns after "JUST PUTTING THE BIO IN THE REQUEST QUEUE OF THE OTHER DEVICE"
* not knowing this, i was killing the bio (which was still in the request queue)

FINE!
i wrote my bi_end_io function and did all ending operations there.........
TADAAAAAA.....
The code worked. Whatever operations tat i did in the pool, got reflected in ram0... Thankyou hari for all your help.! This project is going awesome..... Lots of learning........

NEXT_STEP : one-to-many mappping...