Vnode ops in VFS layer of Kernel (esp. SUN)

[ash at btr.btr.com]

Can anyone out there help me, I need to know what the following vnode functions
in the VFS layer of the Kernel do, especially in SUN OS4;

    vn_getpage()
    vn_putpage()
    vn_map ()

I would really like to know what the arguments to these functions are and how
best to implement them. We have already implemented all the required VNODE
functions except the above, as we do not know what they do.

                            Thanks in advance