Function vnode_pager_dealloc

freebsd/vm/vnode_pager.c:304–344

* The object must be locked. */

 *	The object must be locked.
 */
static void
vnode_pager_dealloc(vm_object_t object)
{
	struct vnode *vp;
	int refs;

	vp = object->handle;
	if (vp == NULL)
		panic("vnode_pager_dealloc: pager already dealloced");

	VM_OBJECT_ASSERT_WLOCKED(object);
	vm_object_pip_wait(object, "vnpdea");
	refs = object->ref_count;

	object->handle = NULL;
	object->type = OBJT_DEAD;
	ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
	if (object->un_pager.vnp.writemappings > 0) {
		object->un_pager.vnp.writemappings = 0;
		VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
		CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
		    __func__, vp, vp->v_writecount);
	}
	vp->v_object = NULL;
	VI_LOCK(vp);

	/*
	 * vm_map_entry_set_vnode_text() cannot reach this vnode by
	 * following object->handle.  Clear all text references now.
	 * This also clears the transient references from
	 * kern_execve(), which is fine because dead_vnodeops uses nop
	 * for VOP_UNSET_TEXT().
	 */
	if (vp->v_writecount < 0)
		vp->v_writecount = 0;
	VI_UNLOCK(vp);
	VM_OBJECT_WUNLOCK(object);
	if (refs > 0)
		vunref(vp);
	VM_OBJECT_WLOCK(object);
}

static boolean_t
vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,