How to use VOP_IOCTL?

[Oleksandr Dudinskyi]

Hi,
I am the GSoC student I need some advice in my project.
http://wiki.freebsd.org/SummerOfCode2012/UDFImplementation
I want to use function VOP_IOCTL() in my project, but not very informative
man, introduced me to the confusion. Specifically I don't know which of the
flags use. In NetBSD after call this function, request proceeds to function
cdioctl () in  sys/dev/scsipi/cd.c . Where the command( one of the
VOP_IOCTL parameters) is selection. Could you tell me how to reach this
logic in Freebsd(call cdioctl () in  sys/cam /scsi/scsi_cd.c)? Or share
some articles on the topic.

-- 
Thank you,
Oleksandr Dudinskyi.