+ # Kernel behavior seems to be that if a file is
+ # referenced, its parents remain referenced too. This
+ # means has_ref() exits early when a collection is not
+ # candidate for eviction.
+ #
+ # By contrast, in_use() doesn't increment references on
+ # parents, so it requires a full tree walk to determine if
+ # a collection is a candidate for eviction. This takes
+ # .07s for 240000 files, which becomes a major drag when
+ # cap_cache is being called several times a second and
+ # there are multiple non-evictable collections in the
+ # cache.
+ #
+ # So it is important for performance that we do the
+ # has_ref() check first.
+
+ if obj.has_ref(True):
+ _logger.debug("InodeCache cannot clear inode %i, still referenced", obj.inode)
+ return
+