Kernel/SysFS: Reduce the responsibilities of the Registry object

Instead, let the /sys/dev/block and /sys/dev/char directories to handle
the registering part of SysFSDeviceComponents by themselves.

Kernel/Devices/Device.cpp

@@ -9,6 +9,8 @@
 #include <Kernel/Devices/DeviceManagement.h>
 #include <Kernel/FileSystem/InodeMetadata.h>
 #include <Kernel/FileSystem/SysFS.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/BlockDevicesDirectory.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/CharacterDevicesDirectory.h>
 #include <Kernel/Sections.h>
 
 namespace Kernel {
@@ -25,7 +27,14 @@ void Device::after_inserting()
     VERIFY(!m_sysfs_component);
     auto sys_fs_component = SysFSDeviceComponent::must_create(*this);
     m_sysfs_component = sys_fs_component;
-    SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> void {
+    if (is_block_device()) {
+        SysFSBlockDevicesDirectory::the().devices_list({}).with([&](auto& list) -> void {
+            list.append(sys_fs_component);
+        });
+        return;
+    }
+    VERIFY(is_character_device());
+    SysFSCharacterDevicesDirectory::the().devices_list({}).with([&](auto& list) -> void {
         list.append(sys_fs_component);
     });
 }
@@ -33,9 +42,16 @@ void Device::after_inserting()
 void Device::will_be_destroyed()
 {
     VERIFY(m_sysfs_component);
-    SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> void {
+    if (is_block_device()) {
-        list.remove(*m_sysfs_component);
+        SysFSBlockDevicesDirectory::the().devices_list({}).with([&](auto& list) -> void {
-    });
+            list.remove(*m_sysfs_component);
+        });
+    } else {
+        VERIFY(is_character_device());
+        SysFSCharacterDevicesDirectory::the().devices_list({}).with([&](auto& list) -> void {
+            list.remove(*m_sysfs_component);
+        });
+    }
     DeviceManagement::the().before_device_removal({}, *this);
     m_state = State::BeingRemoved;
 }

Kernel/FileSystem/SysFS/Component.cpp

@@ -106,7 +106,7 @@ SysFSSymbolicLink::SysFSSymbolicLink(SysFSDirectory const& parent_directory, Sys
 
 ErrorOr<void> SysFSDirectory::traverse_as_directory(FileSystemID fsid, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(SysFSComponentRegistry::the().get_lock());
+    MutexLocker locker(m_traverse_lock);
     VERIFY(m_parent_directory);
     TRY(callback({ "."sv, { fsid, component_index() }, 0 }));
     TRY(callback({ ".."sv, { fsid, m_parent_directory->component_index() }, 0 }));

Kernel/FileSystem/SysFS/Component.h

@@ -81,6 +81,8 @@ protected:
     SysFSDirectory() {};
     explicit SysFSDirectory(SysFSDirectory const& parent_directory);
     NonnullRefPtrVector<SysFSComponent> m_components;
+
+    mutable Mutex m_traverse_lock;
 };
 
 }

Kernel/FileSystem/SysFS/Registry.cpp

@@ -31,15 +31,10 @@ UNMAP_AFTER_INIT SysFSComponentRegistry::SysFSComponentRegistry()
 
 UNMAP_AFTER_INIT void SysFSComponentRegistry::register_new_component(SysFSComponent& component)
 {
-    MutexLocker locker(m_lock);
+    SpinlockLocker locker(m_root_directory_lock);
     m_root_directory->m_components.append(component);
 }
 
-SysFSComponentRegistry::DevicesList& SysFSComponentRegistry::devices_list()
-{
-    return m_devices_list;
-}
-
 SysFSBusDirectory& SysFSComponentRegistry::buses_directory()
 {
     return *m_root_directory->m_buses_directory;

Kernel/FileSystem/SysFS/Registry.h

@@ -16,7 +16,6 @@
 namespace Kernel {
 
 class SysFSComponentRegistry {
-    using DevicesList = MutexProtected<IntrusiveList<&SysFSDeviceComponent::m_list_node>>;
 
 public:
     static SysFSComponentRegistry& the();
@@ -27,17 +26,13 @@ public:
     void register_new_component(SysFSComponent&);
 
     SysFSDirectory& root_directory() { return m_root_directory; }
-    Mutex& get_lock() { return m_lock; }
 
     void register_new_bus_directory(SysFSDirectory&);
     SysFSBusDirectory& buses_directory();
 
-    DevicesList& devices_list();
-
 private:
-    Mutex m_lock;
     NonnullRefPtr<SysFSRootDirectory> m_root_directory;
-    DevicesList m_devices_list;
+    Spinlock m_root_directory_lock;
 };
 
 }

Kernel/FileSystem/SysFS/RootDirectory.cpp

@@ -19,7 +19,7 @@ NonnullRefPtr<SysFSRootDirectory> SysFSRootDirectory::create()
 
 ErrorOr<void> SysFSRootDirectory::traverse_as_directory(FileSystemID fsid, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(SysFSComponentRegistry::the().get_lock());
+    MutexLocker locker(m_traverse_lock);
     TRY(callback({ "."sv, { fsid, component_index() }, 0 }));
     TRY(callback({ ".."sv, { fsid, 0 }, 0 }));
 

Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/BlockDevicesDirectory.cpp

@@ -10,6 +10,8 @@
 
 namespace Kernel {
 
+static SysFSBlockDevicesDirectory* s_the { nullptr };
+
 NonnullRefPtr<SysFSBlockDevicesDirectory> SysFSBlockDevicesDirectory::must_create(SysFSDeviceIdentifiersDirectory const& devices_directory)
 {
     return adopt_ref_if_nonnull(new SysFSBlockDevicesDirectory(devices_directory)).release_nonnull();
@@ -17,6 +19,13 @@ NonnullRefPtr<SysFSBlockDevicesDirectory> SysFSBlockDevicesDirectory::must_creat
 SysFSBlockDevicesDirectory::SysFSBlockDevicesDirectory(SysFSDeviceIdentifiersDirectory const& devices_directory)
     : SysFSDirectory(devices_directory)
 {
+    s_the = this;
+}
+
+SysFSBlockDevicesDirectory& SysFSBlockDevicesDirectory::the()
+{
+    VERIFY(s_the);
+    return *s_the;
 }
 
 ErrorOr<void> SysFSBlockDevicesDirectory::traverse_as_directory(FileSystemID fsid, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
@@ -25,10 +34,9 @@ ErrorOr<void> SysFSBlockDevicesDirectory::traverse_as_directory(FileSystemID fsi
     TRY(callback({ "."sv, { fsid, component_index() }, 0 }));
     TRY(callback({ ".."sv, { fsid, m_parent_directory->component_index() }, 0 }));
 
-    return SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> ErrorOr<void> {
+    return m_devices_list.with([&](auto& list) -> ErrorOr<void> {
         for (auto& exposed_device : list) {
-            if (!exposed_device.is_block_device())
+            VERIFY(exposed_device.is_block_device());
-                continue;
             TRY(callback({ exposed_device.name(), { fsid, exposed_device.component_index() }, 0 }));
         }
         return {};
@@ -37,10 +45,9 @@ ErrorOr<void> SysFSBlockDevicesDirectory::traverse_as_directory(FileSystemID fsi
 
 RefPtr<SysFSComponent> SysFSBlockDevicesDirectory::lookup(StringView name)
 {
-    return SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> RefPtr<SysFSComponent> {
+    return m_devices_list.with([&](auto& list) -> RefPtr<SysFSComponent> {
         for (auto& exposed_device : list) {
-            if (!exposed_device.is_block_device())
+            VERIFY(exposed_device.is_block_device());
-                continue;
             if (exposed_device.name() == name)
                 return exposed_device;
         }

Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/BlockDevicesDirectory.h

@@ -7,10 +7,12 @@
 #pragma once
 
 #include <Kernel/FileSystem/SysFS/Component.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/DeviceComponent.h>
 #include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/Directory.h>
 
 namespace Kernel {
 
+class Device;
 class SysFSBlockDevicesDirectory final : public SysFSDirectory {
 public:
     virtual StringView name() const override { return "block"sv; }
@@ -18,8 +20,15 @@ public:
     virtual ErrorOr<void> traverse_as_directory(FileSystemID, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
     virtual RefPtr<SysFSComponent> lookup(StringView name) override;
 
+    static SysFSBlockDevicesDirectory& the();
+
+    using DevicesList = SpinlockProtected<IntrusiveList<&SysFSDeviceComponent::m_list_node>>;
+    DevicesList& devices_list(Badge<Device>) { return m_devices_list; }
+
 private:
     explicit SysFSBlockDevicesDirectory(SysFSDeviceIdentifiersDirectory const&);
+
+    DevicesList m_devices_list;
 };
 
 }

Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/CharacterDevicesDirectory.cpp

@@ -10,6 +10,8 @@
 
 namespace Kernel {
 
+static SysFSCharacterDevicesDirectory* s_the { nullptr };
+
 NonnullRefPtr<SysFSCharacterDevicesDirectory> SysFSCharacterDevicesDirectory::must_create(SysFSDeviceIdentifiersDirectory const& devices_directory)
 {
     return adopt_ref_if_nonnull(new SysFSCharacterDevicesDirectory(devices_directory)).release_nonnull();
@@ -17,6 +19,7 @@ NonnullRefPtr<SysFSCharacterDevicesDirectory> SysFSCharacterDevicesDirectory::mu
 SysFSCharacterDevicesDirectory::SysFSCharacterDevicesDirectory(SysFSDeviceIdentifiersDirectory const& devices_directory)
     : SysFSDirectory(devices_directory)
 {
+    s_the = this;
 }
 ErrorOr<void> SysFSCharacterDevicesDirectory::traverse_as_directory(FileSystemID fsid, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
 {
@@ -24,22 +27,26 @@ ErrorOr<void> SysFSCharacterDevicesDirectory::traverse_as_directory(FileSystemID
     TRY(callback({ "."sv, { fsid, component_index() }, 0 }));
     TRY(callback({ ".."sv, { fsid, m_parent_directory->component_index() }, 0 }));
 
-    return SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> ErrorOr<void> {
+    return m_devices_list.with([&](auto& list) -> ErrorOr<void> {
         for (auto& exposed_device : list) {
-            if (exposed_device.is_block_device())
+            VERIFY(!exposed_device.is_block_device());
-                continue;
             TRY(callback({ exposed_device.name(), { fsid, exposed_device.component_index() }, 0 }));
         }
         return {};
     });
 }
 
+SysFSCharacterDevicesDirectory& SysFSCharacterDevicesDirectory::the()
+{
+    VERIFY(s_the);
+    return *s_the;
+}
+
 RefPtr<SysFSComponent> SysFSCharacterDevicesDirectory::lookup(StringView name)
 {
-    return SysFSComponentRegistry::the().devices_list().with_exclusive([&](auto& list) -> RefPtr<SysFSComponent> {
+    return m_devices_list.with([&](auto& list) -> RefPtr<SysFSComponent> {
         for (auto& exposed_device : list) {
-            if (exposed_device.is_block_device())
+            VERIFY(!exposed_device.is_block_device());
-                continue;
             if (exposed_device.name() == name)
                 return exposed_device;
         }

Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/CharacterDevicesDirectory.h

@@ -7,10 +7,12 @@
 #pragma once
 
 #include <Kernel/FileSystem/SysFS/Component.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/DeviceComponent.h>
 #include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/Directory.h>
 
 namespace Kernel {
 
+class Device;
 class SysFSCharacterDevicesDirectory final : public SysFSDirectory {
 public:
     virtual StringView name() const override { return "char"sv; }
@@ -18,8 +20,15 @@ public:
     virtual ErrorOr<void> traverse_as_directory(FileSystemID, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
     virtual RefPtr<SysFSComponent> lookup(StringView name) override;
 
+    static SysFSCharacterDevicesDirectory& the();
+
+    using DevicesList = SpinlockProtected<IntrusiveList<&SysFSDeviceComponent::m_list_node>>;
+    DevicesList& devices_list(Badge<Device>) { return m_devices_list; }
+
 private:
     explicit SysFSCharacterDevicesDirectory(SysFSDeviceIdentifiersDirectory const&);
+
+    DevicesList m_devices_list;
 };
 
 }

Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/DeviceComponent.h

@@ -15,7 +15,8 @@ namespace Kernel {
 class SysFSDeviceComponent final
     : public SysFSComponent
     , public Weakable<SysFSDeviceComponent> {
-    friend class SysFSComponentRegistry;
+    friend class SysFSBlockDevicesDirectory;
+    friend class SysFSCharacterDevicesDirectory;
 
 public:
     static NonnullRefPtr<SysFSDeviceComponent> must_create(Device const&);