Duplication of the BIO structure or a request

[Pablo Montesinos Ortego <tobe@xxxxxxxxxxxxxxxxxxx>]

Hi
I am working on a small driver that uses a "make_request" function. 
Whenever my module receives a request from the upper layer, I am trying 
to copy it before sending it to the actual block device.

 However, I don't see any funtion that lets me duplicate the BIO 
structure and its data (or a request).I have tried to increment the 
references to the original BIO structure, but once I modify its bi_bdev 
field and return nonzero (in order to be dispatched to the other 
device's driver) the upper layers seem to delete the data or the 
structure and when I try to process it a few milliseconds later I got a 
wonderful kernel error:

Apr  5 00:43:16 ajo kernel: kernel BUG at 
drivers/block/ll_rw_blk.c:2299!

Is there any way I can duplicate a BIO that is sent to me? Or at least 
prevent it from being deleter until I use it again? Any help would be 
appreciated. I have looked at the RAID source code but I can't find 
anything useful

Thanks

Pablo

PS: In 2.4 it was very easy.. that's why I'm a bit upset :)


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