}
if (end_index >= start_index) {
- unsigned long count = invalidate_mapping_pages(mapping,
+ unsigned long count;
+
+ /*
+ * It's common to FADV_DONTNEED right after
+ * the read or write that instantiates the
+ * pages, in which case there will be some
+ * sitting on the local LRU cache. Try to
+ * avoid the expensive remote drain and the
+ * second cache tree walk below by flushing
+ * them out right away.
+ */
+ lru_add_drain();
+
+ count = invalidate_mapping_pages(mapping,
start_index, end_index);
/*