Kernel: Split the TmpFS core files into smaller components

Author: https://github.com/supercomputer7
Commit: 5e6101dd3e
Pull-request: https://github.com/SerenityOS/serenity/pull/15771
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/bgianfo

Kernel/FileSystem/TmpFS/FileSystem.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <Kernel/FileSystem/FileSystem.h>
+#include <Kernel/FileSystem/Inode.h>
+#include <Kernel/Forward.h>
+
+namespace Kernel {
+
+class TmpFS final : public FileSystem {
+    friend class TmpFSInode;
+
+public:
+    virtual ~TmpFS() override;
+    static ErrorOr<NonnullLockRefPtr<FileSystem>> try_create();
+    virtual ErrorOr<void> initialize() override;
+
+    virtual StringView class_name() const override { return "TmpFS"sv; }
+
+    virtual bool supports_watchers() const override { return true; }
+
+    virtual Inode& root_inode() override;
+
+private:
+    TmpFS();
+
+    LockRefPtr<TmpFSInode> m_root_inode;
+
+    unsigned m_next_inode_index { 1 };
+    unsigned next_inode_index();
+};
+
+}