From 5f57170c385c609701f0e3db23395f72eb78f3ea Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Sun, 23 Aug 2026 15:28:46 +0200
Subject: kernel/fs: devfs: externalize mount state

---
 kernel/kernel/filesystem/devfs/filesystem.cpp | 10 ++++++----
 kernel/kernel/filesystem/devfs/filesystem.hpp |  3 ---
 kernel/kernel/filesystem/vfs.cpp              | 10 ++++++----
 kernel/kernel/filesystem/vfs.hpp              |  3 ++-
 4 files changed, 14 insertions(+), 12 deletions(-)

(limited to 'kernel')

diff --git a/kernel/kernel/filesystem/devfs/filesystem.cpp b/kernel/kernel/filesystem/devfs/filesystem.cpp
index 640a01db..0e3f3164 100644
--- a/kernel/kernel/filesystem/devfs/filesystem.cpp
+++ b/kernel/kernel/filesystem/devfs/filesystem.cpp
@@ -47,13 +47,15 @@ namespace kernel::filesystem::devfs
   [[gnu::used]]
   constexpr auto registration = type_registration<type>{};
 
+  static_assert(sizeof(kernel::filesystem::filesystem) == sizeof(devfs::filesystem));
+
   auto filesystem::mount(inode_ptr const &) -> kstd::result<mount_result>
   {
-    m_root_inode = kstd::make_shared<inode>();
-    return mount_result{m_root_inode, nullptr};
+    auto root = kstd::make_shared<inode>();
+    return mount_result{root, root};
   }
 
-  auto filesystem::lookup(inode_ptr const & parent, std::string_view name, driver_data_ptr) const
+  auto filesystem::lookup(inode_ptr const & parent, std::string_view name, driver_data_ptr driver_data) const
       -> kstd::result<inode_ptr>
   {
     if (!parent)
@@ -66,7 +68,7 @@ namespace kernel::filesystem::devfs
       return kstd::failure(vfs_errc::not_a_directory);
     }
 
-    if (parent.get() != m_root_inode.get())
+    if (parent.get() != driver_data.get())
     {
       return kstd::failure(vfs_errc::invalid_inode);
     }
diff --git a/kernel/kernel/filesystem/devfs/filesystem.hpp b/kernel/kernel/filesystem/devfs/filesystem.hpp
index 147cb692..56744477 100644
--- a/kernel/kernel/filesystem/devfs/filesystem.hpp
+++ b/kernel/kernel/filesystem/devfs/filesystem.hpp
@@ -38,9 +38,6 @@ namespace kernel::filesystem::devfs
                                     driver_data_ptr driver_data,
                                     std::optional<kapi::filesystem::device_number> raw_device = std::nullopt)
         -> kstd::result<inode_ptr> override;
-
-  private:
-    inode_ptr m_root_inode{};
   };
 }  // namespace kernel::filesystem::devfs
 
diff --git a/kernel/kernel/filesystem/vfs.cpp b/kernel/kernel/filesystem/vfs.cpp
index 512b7394..43da7130 100644
--- a/kernel/kernel/filesystem/vfs.cpp
+++ b/kernel/kernel/filesystem/vfs.cpp
@@ -85,7 +85,8 @@ namespace kernel::filesystem
       kapi::system::panic("[FILESYSTEM] failed to mount device FS", device_fs_mount_result.error());
     }
 
-    graft_persistent_device_fs(device_fs, device_fs_mount_result->first);
+    auto [device_fs_root, device_fs_data] = *device_fs_mount_result;
+    graft_persistent_device_fs(device_fs, device_fs_root, device_fs_data);
 
     // mount boot fs at / (shadows rootfs), re-graft devfs
     auto [boot_device_dentry, boot_device_mount_context] =
@@ -103,7 +104,7 @@ namespace kernel::filesystem
             kapi::system::panic("[OS:FS] failed to mount boot FS", mount.error());
           }
           m_mount_table.add_mount(*mount);
-          graft_persistent_device_fs(device_fs, device_fs_mount_result->first);
+          graft_persistent_device_fs(device_fs, device_fs_root, device_fs_data);
         }
       }
     }
@@ -312,7 +313,8 @@ namespace kernel::filesystem
   }
 
   auto vfs::graft_persistent_device_fs(kstd::shared_ptr<filesystem> const & device_fs,
-                                       kstd::shared_ptr<inode> const & root_inode) -> void
+                                       kstd::shared_ptr<inode> const & root_inode, kstd::shared_ptr<void> driver_data)
+      -> void
   {
     auto [root_mount_point_dentry, root_mount] = resolve_path_internal("/").value_or(std::pair{nullptr, nullptr});
     if (root_mount_point_dentry && root_mount)
@@ -324,7 +326,7 @@ namespace kernel::filesystem
         root_mount_point_dentry->add_child(dev_dentry);
       }
 
-      auto new_mount = mount::attach(dev_dentry, device_fs, root_inode, nullptr, root_mount, nullptr);
+      auto new_mount = mount::attach(dev_dentry, device_fs, root_inode, driver_data, root_mount, nullptr);
       m_mount_table.add_mount(new_mount);
     }
   }
diff --git a/kernel/kernel/filesystem/vfs.hpp b/kernel/kernel/filesystem/vfs.hpp
index 1975ac8a..a53ab532 100644
--- a/kernel/kernel/filesystem/vfs.hpp
+++ b/kernel/kernel/filesystem/vfs.hpp
@@ -112,7 +112,8 @@ namespace kernel::filesystem
     [[nodiscard]] auto find_mount(std::string_view path) const -> kstd::result<mount_ptr>;
 
     auto graft_persistent_device_fs(kstd::shared_ptr<filesystem> const & device_fs,
-                                    kstd::shared_ptr<inode> const & root_inode) -> void;
+                                    kstd::shared_ptr<inode> const & root_inode, kstd::shared_ptr<void> driver_data)
+        -> void;
 
     auto create_inode(std::string_view path, kapi::filesystem::file_type type,
                       std::optional<kapi::filesystem::device_number> raw_device = std::nullopt) -> kstd::result<void>;
-- 
cgit v1.2.3