decrement the reference count for a
vnode and unlock it
Decrement the v_usecount field of the vnode vp and unlock the vnode.
This operation is functionally equivalent to calling VOP_UNLOCK(9) followed by vrele(9).
vnode(9), VOP_UNLOCK(9), vref(9), vrele(9)
This man page was originally written by Doug Rabson for FreeBSD.