getting from bio to buf in dastrategy()

[Eno Thereska]

Hi,

 >To: Eno Thereska <eno at andrew.cmu.edu>
 >Date: Mon, 04 Aug 2003 07:43:44 +0200


 >In message <3F2D96AB.9000607 at andrew.cmu.edu>, Eno Thereska writes:
 >>Hi all,
 >>
 >>I am hacking into the FreeBSD 5.0 code.
 >>I jumped from using 4.4 to 5.0 and a couple of things
 >>have changed. Here is my question:
 >>
 >>in /sys/cam/scsi/scsi_da.c the dastrategy()
 >>function takes as an argument "struct bio* bp"
 >>Now I need to get to the "struct *buf" that bp
 >>belongs to.

 >You can't do that, there may not be any struct buf.


How can a bio exist on it's own, unrelated to any buf?
Would that be a special case or does that happen all the
time? A concrete example would help.

Thanks
Eno