Currently there's a significant mess in Lustre code in regards to kernel/user pointers.
Structures are not separated and could be used from both which is bad for multiple reasons.
This also makes it hard for various static tools to properly enforce access rules.

Things like IOC_LIBCFS_DEBUG_PEER "ioctl" should be cleaned out and the __user modifiers added all around in the structures to make everything work nice and well.