diff --git a/model/VolumeBase.cpp b/model/VolumeBase.cpp
index 74bd874..29bc32c 100644
--- a/model/VolumeBase.cpp
+++ b/model/VolumeBase.cpp
@@ -35,7 +35,7 @@
 VolumeBase::VolumeBase(Type type)
     : mType(type),
       mMountFlags(0),
-      mMountUserId(-1),
+      mMountUserId(USER_UNKNOWN),
       mCreated(false),
       mState(State::kUnmounted),
       mSilent(false) {}
@@ -230,10 +230,9 @@
     setState(State::kChecking);
     status_t res = doMount();
     if (res == OK) {
-        setState(State::kMounted);
-    } else {
-        setState(State::kUnmountable);
+        res = VolumeManager::Instance()->onVolumeMounted(this);
     }
+    setState(res == OK ? State::kMounted : State::kUnmountable);
 
     return res;
 }
@@ -252,8 +251,11 @@
     }
     mVolumes.clear();
 
-    status_t res = doUnmount();
-    setState(State::kUnmounted);
+    status_t res = VolumeManager::Instance()->onVolumeUnmounted(this);
+    if (res == OK) {
+        res = doUnmount();
+        setState(State::kUnmounted);
+    }
     return res;
 }
 
@@ -277,5 +279,10 @@
     return -ENOTSUP;
 }
 
+std::ostream& VolumeBase::operator<<(std::ostream& stream) const {
+    return stream << " VolumeBase{id=" << mId << ",label=" << mLabel
+                  << ",mountFlags=" << mMountFlags << ",mountUserId=" << mMountUserId << "}";
+}
+
 }  // namespace vold
 }  // namespace android