Kernel/SysFS: Stop cluttering the codebase with pieces of SysFS parts

Instead, start to put everything in one place to resemble the directory
structure of the SysFS when actually using it.

Kernel/FileSystem/SysFS/Component.cpp

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/FileSystem/SysFS.h>
+#include <Kernel/FileSystem/SysFS/Component.h>
+
+namespace Kernel {
+
+static Spinlock s_index_lock;
+static InodeIndex s_next_inode_index { 0 };
+
+static size_t allocate_inode_index()
+{
+    SpinlockLocker lock(s_index_lock);
+    s_next_inode_index = s_next_inode_index.value() + 1;
+    VERIFY(s_next_inode_index > 0);
+    return s_next_inode_index.value();
+}
+
+SysFSComponent::SysFSComponent()
+    : m_component_index(allocate_inode_index())
+{
+}
+
+mode_t SysFSComponent::permissions() const
+{
+    return S_IRUSR | S_IRGRP | S_IROTH;
+}
+
+ErrorOr<void> SysFSDirectory::traverse_as_directory(FileSystemID fsid, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
+{
+    MutexLocker locker(SysFSComponentRegistry::the().get_lock());
+    VERIFY(m_parent_directory);
+    TRY(callback({ ".", { fsid, component_index() }, 0 }));
+    TRY(callback({ "..", { fsid, m_parent_directory->component_index() }, 0 }));
+
+    for (auto& component : m_components) {
+        InodeIdentifier identifier = { fsid, component.component_index() };
+        TRY(callback({ component.name(), identifier, 0 }));
+    }
+    return {};
+}
+
+RefPtr<SysFSComponent> SysFSDirectory::lookup(StringView name)
+{
+    for (auto& component : m_components) {
+        if (component.name() == name) {
+            return component;
+        }
+    }
+    return {};
+}
+
+SysFSDirectory::SysFSDirectory(SysFSDirectory const& parent_directory)
+    : SysFSComponent()
+    , m_parent_directory(parent_directory)
+{
+}
+
+ErrorOr<NonnullRefPtr<SysFSInode>> SysFSDirectory::to_inode(SysFS const& sysfs_instance) const
+{
+    return TRY(SysFSDirectoryInode::try_create(sysfs_instance, *this));
+}
+
+ErrorOr<NonnullRefPtr<SysFSInode>> SysFSComponent::to_inode(SysFS const& sysfs_instance) const
+{
+    return SysFSInode::try_create(sysfs_instance, *this);
+}
+
+}