Revert "Stop dropping caches now we have kernel fix"
am: 8ad0bef7b5

Change-Id: I318b956c38175abada5a2423b8d920b299883030
diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp
index 9dfcad8..88bedd0 100644
--- a/Ext4Crypt.cpp
+++ b/Ext4Crypt.cpp
@@ -171,6 +171,13 @@
     LOG(DEBUG) << "Added key " << key_id << " (" << ref << ") to keyring " << device_keyring
                << " in process " << getpid();
 
+    // *TODO* Remove this code when kernel is fixed - see b/28373400
+    // Kernel preserves caches across a key insertion with ext4ice, which leads
+    // to contradictory dirents
+    if (!android::base::WriteStringToFile("3", "/proc/sys/vm/drop_caches")) {
+        PLOG(ERROR) << "Failed to drop_caches";
+    }
+
     return true;
 }