Keep an immutable copy for every scanned Device* to avoid rescans.

src/modules/partition/core/PartitionCoreModule.cpp

@@ -97,6 +97,7 @@ isIso9660( const Device* device )
 PartitionCoreModule::DeviceInfo::DeviceInfo( Device* _device )
     : device( _device )
     , partitionModel( new PartitionModel )
+    , immutableDevice( new Device( *_device ) )
 {}
 
 PartitionCoreModule::DeviceInfo::~DeviceInfo()
@@ -235,7 +236,7 @@ PartitionCoreModule::bootLoaderModel() const
 }
 
 PartitionModel*
-PartitionCoreModule::partitionModelForDevice( Device* device ) const
+PartitionCoreModule::partitionModelForDevice( const Device* device ) const
 {
     DeviceInfo* info = infoForDevice( device );
     Q_ASSERT( info );
@@ -244,14 +245,14 @@ PartitionCoreModule::partitionModelForDevice( Device* device ) const
 
 
 Device*
-PartitionCoreModule::createImmutableDeviceCopy( Device* device )
+PartitionCoreModule::immutableDeviceCopy( const Device* device )
 {
-    CoreBackend* backend = CoreBackendManager::self()->backend();
+    Q_ASSERT( device );
+    DeviceInfo* info = infoForDevice( device );
+    if ( !info )
+        return nullptr;
 
-    QString node = device->deviceNode();
-    cDebug() << "Creating immutable copy for node:" << node;
-    Device* deviceBefore = backend->scanDevice( node );
-    return deviceBefore;
+    return info->immutableDevice.data();
 }
 
 
@@ -581,12 +582,15 @@ PartitionCoreModule::scanForEfiSystemPartitions()
 }
 
 PartitionCoreModule::DeviceInfo*
-PartitionCoreModule::infoForDevice( Device* device ) const
+PartitionCoreModule::infoForDevice( const Device* device ) const
 {
-    for ( auto deviceInfo : m_deviceInfos )
+    for ( auto it = m_deviceInfos.constBegin();
+          it != m_deviceInfos.constEnd(); ++it )
     {
-        if ( deviceInfo->device.data() == device )
-            return deviceInfo;
+        if ( ( *it )->device.data() == device )
+            return *it;
+        if ( ( *it )->immutableDevice.data() == device )
+            return *it;
     }
     return nullptr;
 }

src/modules/partition/core/PartitionCoreModule.h

@@ -68,7 +68,7 @@ public:
 
     DeviceModel* deviceModel() const;
 
-    PartitionModel* partitionModelForDevice( Device* device ) const;
+    PartitionModel* partitionModelForDevice( const Device* device ) const;
 
     //HACK: all devices change over time, and together make up the state of the CoreModule.
     //      However this makes it hard to show the *original* state of a device.
@@ -77,7 +77,7 @@ public:
     //      This should probably be redone some other way.
     //              -- Teo 4/2015
     //FIXME: make this horrible method private. -- Teo 12/2015
-    static Device* createImmutableDeviceCopy( Device* device );
+    Device* immutableDeviceCopy( const Device* device );
 
     QAbstractItemModel* bootLoaderModel() const;
 
@@ -147,6 +147,7 @@ private:
         ~DeviceInfo();
         QScopedPointer< Device > device;
         QScopedPointer< PartitionModel > partitionModel;
+        const QScopedPointer< Device > immutableDevice;
         QList< Calamares::job_ptr > jobs;
 
         void forgetChanges();
@@ -166,7 +167,7 @@ private:
     void updateIsDirty();
     void scanForEfiSystemPartitions();
 
-    DeviceInfo* infoForDevice( Device* ) const;
+    DeviceInfo* infoForDevice( const Device* ) const;
 
     OsproberEntryList m_osproberLines;
 

src/modules/partition/gui/ChoicePage.cpp

@@ -813,7 +813,7 @@ ChoicePage::updateDeviceStatePreview()
     m_beforePartitionLabelsView = new PartitionLabelsView( m_previewBeforeFrame );
     m_beforePartitionLabelsView->setExtendedPartitionHidden( mode == PartitionBarsView::NoNestedPartitions );
 
-    Device* deviceBefore = m_core->createImmutableDeviceCopy( currentDevice );
+    Device* deviceBefore = m_core->immutableDeviceCopy( currentDevice );
 
     PartitionModel* model = new PartitionModel( m_beforePartitionBarsView );
     model->init( deviceBefore, m_core->osproberEntries() );