Merge from vmc-playground:

Introduce a new KPI that verifies if the page cache is empty for a
specified vm_object.  This KPI does not make assumptions about the
locking in order to be used also for building assertions at init and
destroy time.
It is mostly used to hide implementation details of the page cache.

Sponsored by:	EMC / Isilon storage division
Reviewed by:	jeff
Reviewed by:	alc (vm_radix based version)
Tested by:	flo, pho, jhb, davide

1 files changed, 6 insertions, 5 deletions

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 1e588e3..372782b 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -173,7 +173,7 @@ vm_object_zdtor(void *mem, int size, void *arg)
 	    ("object %p has reservations",
 	    object));
 #endif
-	KASSERT(object->cache == NULL,
+	KASSERT(vm_object_cache_is_empty(object),
 	    ("object %p has cached pages",
 	    object));
 	KASSERT(object->paging_in_progress == 0,
@@ -752,7 +752,7 @@ vm_object_terminate(vm_object_t object)
 	if (__predict_false(!LIST_EMPTY(&object->rvq)))
 		vm_reserv_break_all(object);
 #endif
-	if (__predict_false(object->cache != NULL))
+	if (__predict_false(!vm_object_cache_is_empty(object)))
 		vm_page_cache_free(object, 0, 0);
 
 	/*
@@ -1377,7 +1377,7 @@ retry:
 		 * should still be OBJT_DEFAULT and orig_object should not
 		 * contain any cached pages within the specified range.
 		 */
-		if (__predict_false(orig_object->cache != NULL))
+		if (__predict_false(!vm_object_cache_is_empty(orig_object)))
 			vm_page_cache_transfer(orig_object, offidxstart,
 			    new_object);
 	}
@@ -1726,7 +1726,8 @@ vm_object_collapse(vm_object_t object)
 				/*
 				 * Free any cached pages from backing_object.
 				 */
-				if (__predict_false(backing_object->cache != NULL))
+				if (__predict_false(
+				    !vm_object_cache_is_empty(backing_object)))
 					vm_page_cache_free(backing_object, 0, 0);
 			}
 			/*
@@ -1920,7 +1921,7 @@ again:
 	}
 	vm_object_pip_wakeup(object);
 skipmemq:
-	if (__predict_false(object->cache != NULL))
+	if (__predict_false(!vm_object_cache_is_empty(object)))
 		vm_page_cache_free(object, start, end);
 }