Kernel: Make FileSystem::root_inode() return a plain Inode&

All file system classes are expected to keep their root Inode object
in memory, so this function can safely return an Inode&.

Kernel/FileSystem/DevFS.cpp

@@ -61,7 +61,7 @@ bool DevFS::initialize()
     return true;
 }
 
-NonnullRefPtr<Inode> DevFS::root_inode() const
+Inode& DevFS::root_inode()
 {
     return *m_root_inode;
 }

Kernel/FileSystem/DevFS.h

@@ -28,7 +28,7 @@ public:
     void notify_new_device(Device&);
     void notify_device_removal(Device&);
 
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Inode& root_inode() override;
 
 private:
     DevFS();

Kernel/FileSystem/DevPtsFS.cpp

@@ -51,7 +51,7 @@ static InodeIndex pty_index_to_inode_index(unsigned pty_index)
     return pty_index + 2;
 }
 
-NonnullRefPtr<Inode> DevPtsFS::root_inode() const
+Inode& DevPtsFS::root_inode()
 {
     return *m_root_inode;
 }

Kernel/FileSystem/DevPtsFS.h

@@ -25,7 +25,7 @@ public:
     virtual bool initialize() override;
     virtual StringView class_name() const override { return "DevPtsFS"sv; }
 
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Inode& root_inode() override;
 
     static void register_slave_pty(SlavePTY&);
     static void unregister_slave_pty(SlavePTY&);

Kernel/FileSystem/Ext2FileSystem.cpp

@@ -154,7 +154,7 @@ bool Ext2FS::initialize()
     return true;
 }
 
-NonnullRefPtr<Inode> Ext2FS::root_inode() const
+Ext2FSInode& Ext2FS::root_inode()
 {
     return *m_root_inode;
 }

Kernel/FileSystem/Ext2FileSystem.h

@@ -128,7 +128,7 @@ private:
     bool flush_super_block();
 
     virtual StringView class_name() const override { return "Ext2FS"sv; }
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Ext2FSInode& root_inode() override;
     RefPtr<Inode> get_inode(InodeIdentifier) const;
     KResultOr<NonnullRefPtr<Inode>> create_inode(Ext2FSInode& parent_inode, const String& name, mode_t, dev_t, uid_t, gid_t);
     KResult create_directory(Ext2FSInode& parent_inode, const String& name, mode_t, uid_t, gid_t);

Kernel/FileSystem/FileSystem.h

@@ -33,7 +33,7 @@ public:
 
     virtual bool initialize() = 0;
     virtual StringView class_name() const = 0;
-    virtual NonnullRefPtr<Inode> root_inode() const = 0;
+    virtual Inode& root_inode() = 0;
     virtual bool supports_watchers() const { return false; }
 
     bool is_readonly() const { return m_readonly; }

Kernel/FileSystem/Plan9FileSystem.cpp

@@ -243,7 +243,7 @@ Plan9FS::ProtocolVersion Plan9FS::parse_protocol_version(const StringView& s) co
     return ProtocolVersion::v9P2000;
 }
 
-NonnullRefPtr<Inode> Plan9FS::root_inode() const
+Inode& Plan9FS::root_inode()
 {
     return *m_root_inode;
 }

Kernel/FileSystem/Plan9FileSystem.h

@@ -26,7 +26,7 @@ public:
 
     virtual bool supports_watchers() const override { return false; }
 
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Inode& root_inode() override;
 
     u16 allocate_tag() { return m_next_tag++; }
     u32 allocate_fid() { return m_next_fid++; }

Kernel/FileSystem/ProcFS.cpp

@@ -64,7 +64,7 @@ bool ProcFS::initialize()
     return true;
 }
 
-NonnullRefPtr<Inode> ProcFS::root_inode() const
+Inode& ProcFS::root_inode()
 {
     return *m_root_inode;
 }

Kernel/FileSystem/ProcFS.h

@@ -28,7 +28,7 @@ public:
     virtual bool initialize() override;
     virtual StringView class_name() const override { return "ProcFS"sv; }
 
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Inode& root_inode() override;
 
 private:
     ProcFS();

Kernel/FileSystem/SysFS.cpp

@@ -80,7 +80,7 @@ bool SysFS::initialize()
     return true;
 }
 
-NonnullRefPtr<Inode> SysFS::root_inode() const
+Inode& SysFS::root_inode()
 {
     return *m_root_inode;
 }

Kernel/FileSystem/SysFS.h

@@ -65,7 +65,7 @@ public:
     virtual bool initialize() override;
     virtual StringView class_name() const override { return "SysFS"sv; }
 
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Inode& root_inode() override;
 
 private:
     SysFS();

Kernel/FileSystem/TmpFS.cpp

@@ -30,10 +30,9 @@ bool TmpFS::initialize()
     return !m_root_inode.is_null();
 }
 
-NonnullRefPtr<Inode> TmpFS::root_inode() const
+Inode& TmpFS::root_inode()
 {
     VERIFY(!m_root_inode.is_null());
-
     return *m_root_inode;
 }
 

Kernel/FileSystem/TmpFS.h

@@ -28,7 +28,7 @@ public:
 
     virtual bool supports_watchers() const override { return true; }
 
-    virtual NonnullRefPtr<Inode> root_inode() const override;
+    virtual Inode& root_inode() override;
 
 private:
     TmpFS();

Kernel/FileSystem/VirtualFileSystem.cpp

@@ -121,13 +121,13 @@ bool VirtualFileSystem::mount_root(FileSystem& fs)
 
     Mount mount { fs, nullptr, root_mount_flags };
 
-    auto root_inode = fs.root_inode();
-    if (!root_inode->is_directory()) {
-        dmesgln("VirtualFileSystem: root inode ({}) for / is not a directory :(", root_inode->identifier());
+    auto& root_inode = fs.root_inode();
+    if (!root_inode.is_directory()) {
+        dmesgln("VirtualFileSystem: root inode ({}) for / is not a directory :(", root_inode.identifier());
         return false;
     }
 
-    m_root_inode = move(root_inode);
+    m_root_inode = root_inode;
     dmesgln("VirtualFileSystem: mounted root from {} ({})", fs.class_name(), static_cast<FileBackedFileSystem&>(fs).file_description().absolute_path());
 
     m_mounts.append(move(mount));
@@ -172,7 +172,7 @@ KResult VirtualFileSystem::traverse_directory_inode(Inode& dir_inode, Function<b
             resolved_inode = entry.inode;
 
         // FIXME: This is now broken considering chroot and bind mounts.
-        bool is_root_inode = dir_inode.identifier() == dir_inode.fs().root_inode()->identifier();
+        bool is_root_inode = dir_inode.identifier() == dir_inode.fs().root_inode().identifier();
         if (is_root_inode && !is_vfs_root(dir_inode.identifier()) && entry.name == "..") {
             auto mount = find_mount_for_guest(dir_inode.identifier());
             VERIFY(mount);