very similar to the issue with nfs41_open_state, an abandoned upcall could outlive its mount. to prevent their nfs41_root from being freed, upcalls need to hold a reference until they're finished. this also keeps all of its clients/sessions/rpc connections alive
Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>
added call to upcall_cleanup() after both upcall_marshall() and upcall_cancel()
individual upcall operations define their nfs41_upcall_op structs locally, instead of putting tons of function prototypes in upcall.c
made the upcall_marshall() function optional; most marshall functions are noops
Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>
