kernel: Add a subclass of VFS::Inode to make it easier to implement file inodes

kernel/src/fs/VFS.h

@@ -20,7 +20,23 @@ namespace VFS
 
         virtual ~Inode() = default;
 
-        InodeType type;
+        virtual InodeType type() const = 0;
+    };
+
+    class FileInode : Inode
+    {
+      public:
+        Result<Inode*> find(const char*) const override
+        {
+            return err(ENOTDIR);
+        }
+
+        InodeType type() const override
+        {
+            return InodeType::RegularFile;
+        }
+
+        virtual ~FileInode() = default;
     };
 
     class FileSystem

kernel/src/fs/tmpfs/FileSystem.h

@@ -26,18 +26,13 @@ namespace TmpFS
         Vector<SharedPtr<VFS::Inode>> m_inodes;
     };
 
-    class Inode : public VFS::Inode
+    class Inode : public VFS::FileInode
     {
       public:
         Inode();
 
         void set_fs(FileSystem& fs, Badge<FileSystem>);
 
-        Result<VFS::Inode*> find(const char*) const override
-        {
-            return err(ENOTSUP);
-        }
-
         VFS::FileSystem& fs() const override
         {
             return *m_fs;