[partition] Check for LVs that will be formatted, don't close them

- when (manually) using an existing LV, it shouldn't be closed
  prior to formatting, since that kills the volume and then the
  path (/dev/myvg/mylv) no longer exists. Then creating the
  filesysytem on that device path fails.

src/modules/partition/core/PartitionCoreModule.cpp

@@ -580,6 +580,42 @@ PartitionCoreModule::setPartitionFlags( Device* device, Partition* partition, Pa
     PartitionInfo::setFlags( partition, flags );
 }
 
+STATICTEST QStringList
+findEssentialLVs( const QList< PartitionCoreModule::DeviceInfo* >& infos )
+{
+    QStringList doNotClose;
+    cDebug() << "Checking LVM use on" << infos.count() << "devices";
+    for ( const auto* info : infos )
+    {
+        if ( info->device->type() != Device::Type::LVM_Device )
+        {
+            continue;
+        }
+
+        for ( const auto& j : qAsConst( info->jobs() ) )
+        {
+            FormatPartitionJob* format = dynamic_cast< FormatPartitionJob* >( j.data() );
+            if ( format )
+            {
+                // device->deviceNode() is /dev/<vg name>
+                // partition()->partitionPath() is /dev/<vg name>/<lv>
+                const auto* partition = format->partition();
+                const QString partPath = partition->partitionPath();
+                const QString devicePath = info->device->deviceNode() + '/';
+                const bool isLvm = partition->roles().has( PartitionRole::Lvm_Lv );
+                if ( isLvm && partPath.startsWith( devicePath ) )
+                {
+                    cDebug() << Logger::SubEntry << partPath
+                             << "is an essential LV filesystem=" << partition->fileSystem().type();
+                    QString lvName = partPath.right( partPath.length() - devicePath.length() );
+                    doNotClose.append( info->device->name() + '-' + lvName );
+                }
+            }
+        }
+    }
+    return doNotClose;
+}
+
 Calamares::JobList
 PartitionCoreModule::jobs( const Config* config ) const
 {
@@ -604,11 +640,15 @@ PartitionCoreModule::jobs( const Config* config ) const
     lst << automountControl;
     lst << Calamares::job_ptr( new ClearTempMountsJob() );
 
+    const QStringList doNotClose = findEssentialLVs( m_deviceInfos );
+
     for ( const auto* info : m_deviceInfos )
     {
         if ( info->isDirty() )
         {
-            lst << Calamares::job_ptr( new ClearMountsJob( info->device.data() ) );
+            auto* job = new ClearMountsJob( info->device.data() );
+            job->setMapperExceptions( doNotClose );
+            lst << Calamares::job_ptr( job );
         }
     }
 

src/modules/partition/core/PartitionCoreModule.h

@@ -84,6 +84,8 @@ public:
         PartitionModel* partitionModelAfter;
     };
 
+    struct DeviceInfo;
+
     PartitionCoreModule( QObject* parent = nullptr );
     ~PartitionCoreModule() override;
 
@@ -239,7 +241,6 @@ Q_SIGNALS:
     void deviceReverted( Device* device );
 
 private:
-    struct DeviceInfo;
     void refreshAfterModelChange();
 
     void doInit();