Function vm_page_set_invalid

freebsd/vm/vm_page.c:5212–5243

* vm_page_set_invalid: * * Invalidates DEV_BSIZE'd chunks within a page. Both the * valid and dirty bits for the effected areas are cleared. */

 *	valid and dirty bits for the effected areas are cleared.
 */
void
vm_page_set_invalid(vm_page_t m, int base, int size)
{
	vm_page_bits_t bits;
	vm_object_t object;

	/*
	 * The object lock is required so that pages can't be mapped
	 * read-only while we're in the process of invalidating them.
	 */
	object = m->object;
	VM_OBJECT_ASSERT_WLOCKED(object);
	vm_page_assert_busied(m);

	if (object->type == OBJT_VNODE && base == 0 && IDX_TO_OFF(m->pindex) +
	    size >= object->un_pager.vnp.vnp_size)
		bits = VM_PAGE_BITS_ALL;
	else
		bits = vm_page_bits(base, size);
	if (object->ref_count != 0 && vm_page_all_valid(m) && bits != 0)
		pmap_remove_all(m);
	KASSERT((bits == 0 && vm_page_all_valid(m)) ||
	    !pmap_page_is_mapped(m),
	    ("vm_page_set_invalid: page %p is mapped", m));
	if (vm_page_xbusied(m)) {
		m->valid &= ~bits;
		m->dirty &= ~bits;
	} else {
		vm_page_bits_clear(m, &m->valid, bits);
		vm_page_bits_clear(m, &m->dirty, bits);
	}
}

/*
 *	vm_page_invalid: