dangling nfs4 debug code should be removed
NFS4 contains what looks like left over debugging code, defining protypes for nfs4_debug_mutex_exit/enter and mutex_exit/enter macros to use them in place of the regular calls. However, the actual implementation of these seems to be absent, the rest should be removed too.
Below that is other code which looks like it should also be removed:
source:usr/src/uts/common/nfs/nfs4.h#L973 (through 991)
Which points us to VOLATILE_FH_TEST, which litters the NFS related code, and is similarly dangling.