Kernel/Devices: Defer creation of SysFS component after the constructor

Instead of doing so in the constructor, let's do immediately after the
constructor, so we can safely pass a reference of a Device, so the
SysFSDeviceComponent constructor can use that object to identify whether
it's a block device or a character device.
This allows to us to not hold a device in SysFSDeviceComponent with a
RefPtr.
Also, we also call the before_removing method in both SlavePTY::unref
and File::unref, so because Device has that method being overrided, it
can ensure the device is removed always cleanly.

Kernel/Storage/PATADiskDevice.cpp

@@ -15,7 +15,10 @@ namespace Kernel {
 
 UNMAP_AFTER_INIT NonnullRefPtr<PATADiskDevice> PATADiskDevice::create(const IDEController& controller, IDEChannel& channel, DriveType type, InterfaceType interface_type, u16 capabilities, u64 max_addressable_block)
 {
-    return adopt_ref(*new PATADiskDevice(controller, channel, type, interface_type, capabilities, max_addressable_block));
+    auto device_or_error = try_create_device<PATADiskDevice>(controller, channel, type, interface_type, capabilities, max_addressable_block);
+    // FIXME: Find a way to propagate errors
+    VERIFY(!device_or_error.is_error());
+    return device_or_error.release_value();
 }
 
 UNMAP_AFTER_INIT PATADiskDevice::PATADiskDevice(const IDEController& controller, IDEChannel& channel, DriveType type, InterfaceType interface_type, u16 capabilities, u64 max_addressable_block)

Kernel/Storage/PATADiskDevice.h

@@ -44,9 +44,10 @@ public:
     virtual void start_request(AsyncBlockDeviceRequest&) override;
     virtual String storage_name() const override;
 
-private:
+    // FIXME: We expose this constructor to make try_create_device helper to work
     PATADiskDevice(const IDEController&, IDEChannel&, DriveType, InterfaceType, u16, u64);
 
+private:
     // ^DiskDevice
     virtual StringView class_name() const override;
 

Kernel/Storage/Partition/DiskPartition.cpp

@@ -12,7 +12,10 @@ namespace Kernel {
 
 NonnullRefPtr<DiskPartition> DiskPartition::create(BlockDevice& device, unsigned minor_number, DiskPartitionMetadata metadata)
 {
-    return adopt_ref(*new DiskPartition(device, minor_number, metadata));
+    auto partition_or_error = try_create_device<DiskPartition>(device, minor_number, metadata);
+    // FIXME: Find a way to propagate errors
+    VERIFY(!partition_or_error.is_error());
+    return partition_or_error.release_value();
 }
 
 DiskPartition::DiskPartition(BlockDevice& device, unsigned minor_number, DiskPartitionMetadata metadata)

Kernel/Storage/Partition/DiskPartition.h

@@ -28,11 +28,12 @@ public:
 
     const DiskPartitionMetadata& metadata() const;
 
+    // FIXME: We expose this constructor to make try_create_device helper to work
+    DiskPartition(BlockDevice&, unsigned, DiskPartitionMetadata);
+
 private:
     virtual StringView class_name() const override;
 
-    DiskPartition(BlockDevice&, unsigned, DiskPartitionMetadata);
-
     WeakPtr<BlockDevice> m_device;
     DiskPartitionMetadata m_metadata;
 };

Kernel/Storage/RamdiskDevice.cpp

@@ -14,7 +14,10 @@ namespace Kernel {
 
 NonnullRefPtr<RamdiskDevice> RamdiskDevice::create(const RamdiskController& controller, NonnullOwnPtr<Memory::Region>&& region, int major, int minor)
 {
-    return adopt_ref(*new RamdiskDevice(controller, move(region), major, minor));
+    auto device_or_error = try_create_device<RamdiskDevice>(controller, move(region), major, minor);
+    // FIXME: Find a way to propagate errors
+    VERIFY(!device_or_error.is_error());
+    return device_or_error.release_value();
 }
 
 RamdiskDevice::RamdiskDevice(const RamdiskController& controller, NonnullOwnPtr<Memory::Region>&& region, int major, int minor)

Kernel/Storage/SATADiskDevice.cpp

@@ -14,7 +14,10 @@ namespace Kernel {
 
 NonnullRefPtr<SATADiskDevice> SATADiskDevice::create(const AHCIController& controller, const AHCIPort& port, size_t sector_size, u64 max_addressable_block)
 {
-    return adopt_ref(*new SATADiskDevice(controller, port, sector_size, max_addressable_block));
+    auto device_or_error = try_create_device<SATADiskDevice>(controller, port, sector_size, max_addressable_block);
+    // FIXME: Find a way to propagate errors
+    VERIFY(!device_or_error.is_error());
+    return device_or_error.release_value();
 }
 
 SATADiskDevice::SATADiskDevice(const AHCIController& controller, const AHCIPort& port, size_t sector_size, u64 max_addressable_block)

Kernel/Storage/SATADiskDevice.h

@@ -32,9 +32,10 @@ public:
     virtual void start_request(AsyncBlockDeviceRequest&) override;
     virtual String storage_name() const override;
 
-private:
+    // FIXME: We expose this constructor to make try_create_device helper to work
     SATADiskDevice(const AHCIController&, const AHCIPort&, size_t sector_size, u64 max_addressable_block);
 
+private:
     // ^DiskDevice
     virtual StringView class_name() const override;
     WeakPtr<AHCIPort> m_port;