From dfaff1dc153eee36dc52c27d704054c513398c5e Mon Sep 17 00:00:00 2001
From: Youkichi Hosoi <youkichihosoi@google.com>
Date: Thu, 25 Nov 2021 16:24:35 +0900
Subject: [PATCH] Remove StubVolume disks upon vold reset events

StubVolumes are managed from outside Android (e.g. from Chrome OS). So,
their disk recreation on vold reset events should also be handled from
outside by 1) listening to reset events, and 2) calling
createStubVolume() for existing StubVolumes on reset events.

Bug: 175281783
Test: m
Test: (Tested in R) Manually induce a vold reset event, and confirm that
Test: 1) vold does not crash, and 2) existing volumes are successfully
Test: mounted again (by calling createStubVolume() for StubVolumes).
Change-Id: I4628eabf809037a547aeef43faedf4dfa57529a6
---
 VolumeManager.cpp | 13 ++++++++++++-
 model/Disk.h      |  4 ++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index 02025b7..9311321 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -899,10 +899,21 @@ int VolumeManager::reset() {
     }
     mInternalEmulatedVolumes.clear();
 
+    // Destroy and recreate all disks except that StubVolume disks are just
+    // destroyed and removed from both mDisks and mPendingDisks.
+    // StubVolumes are managed from outside Android (e.g. from Chrome OS) and
+    // their disk recreation on reset events should be handled from outside by
+    // calling createStubVolume() again.
     for (const auto& disk : mDisks) {
         disk->destroy();
-        disk->create();
+        if (!disk->isStub()) {
+            disk->create();
+        }
     }
+    const auto isStub = [](const auto& disk) { return disk->isStub(); };
+    mDisks.remove_if(isStub);
+    mPendingDisks.remove_if(isStub);
+
     updateVirtualDisk();
     mAddedUsers.clear();
     mStartedUsers.clear();
diff --git a/model/Disk.h b/model/Disk.h
index 16476dc..8c75f59 100644
--- a/model/Disk.h
+++ b/model/Disk.h
@@ -70,6 +70,8 @@ class Disk {
     const std::string& getLabel() const { return mLabel; }
     int getFlags() const { return mFlags; }
 
+    bool isStub() const { return (mFlags & kStubInvisible) || (mFlags & kStubVisible); }
+
     std::shared_ptr<VolumeBase> findVolume(const std::string& id);
 
     void listVolumes(VolumeBase::Type type, std::list<std::string>& list) const;
@@ -123,8 +125,6 @@ class Disk {
 
     int getMaxMinors();
 
-    bool isStub() { return (mFlags & kStubInvisible) || (mFlags & kStubVisible); }
-
     DISALLOW_COPY_AND_ASSIGN(Disk);
 };