From 1d647adb1ba20121eeb5c8e4470f48b2e972b3d4 Mon Sep 17 00:00:00 2001
From: Lukas Oesch <lukasoesch20@gmail.com>
Date: Fri, 15 May 2026 16:50:55 +0200
Subject: Mount can only be unmounted if no references are present, increment
 references on open file and decrement on close file

---
 kernel/include/kernel/filesystem/mount.hpp            | 19 ++++++++++++++++++-
 kernel/include/kernel/filesystem/mount_table.hpp      |  3 ++-
 .../kernel/filesystem/open_file_descriptor.hpp        |  8 +++++++-
 kernel/include/kernel/filesystem/vfs.hpp              |  8 ++++++++
 4 files changed, 35 insertions(+), 3 deletions(-)

(limited to 'kernel/include')

diff --git a/kernel/include/kernel/filesystem/mount.hpp b/kernel/include/kernel/filesystem/mount.hpp
index f920891..fb5a627 100644
--- a/kernel/include/kernel/filesystem/mount.hpp
+++ b/kernel/include/kernel/filesystem/mount.hpp
@@ -54,12 +54,29 @@ namespace kernel::filesystem
     */
     [[nodiscard]] auto get_parent_mount() const -> kstd::shared_ptr<mount> const &;
 
+    /**
+    @brief Increment the reference count for this mount.
+    */
+    auto increment_ref_count() -> void;
+
+    /**
+    @brief Decrement the reference count for this mount.
+    @return True if the reference count reached zero, false otherwise.
+    */
+    auto decrement_ref_count() -> bool;
+
+    /**
+    @brief Check if the mount is ready to be unmounted.
+    @return True if the mount is ready to be unmounted, false otherwise.
+    */
+    [[nodiscard]] auto is_ready_to_unmount() const -> bool;
+
   private:
     kstd::shared_ptr<dentry> m_mount_dentry;
     kstd::shared_ptr<dentry> m_root_dentry;
     kstd::shared_ptr<filesystem> m_filesystem{};
     kstd::shared_ptr<mount> m_parent_mount{};
-    std::atomic_uint32_t m_ref_count{0};  // TODO BA-FS26
+    std::atomic_size_t m_ref_count;
   };
 }  // namespace kernel::filesystem
 
diff --git a/kernel/include/kernel/filesystem/mount_table.hpp b/kernel/include/kernel/filesystem/mount_table.hpp
index 742c928..4f2d1b7 100644
--- a/kernel/include/kernel/filesystem/mount_table.hpp
+++ b/kernel/include/kernel/filesystem/mount_table.hpp
@@ -22,7 +22,8 @@ namespace kernel::filesystem
     {
       removed = 0,
       has_child_mounts = -1,
-      mount_not_found = -2
+      mount_not_found = -2,
+      cannot_be_unmounted = -3
     };
 
     /**
diff --git a/kernel/include/kernel/filesystem/open_file_descriptor.hpp b/kernel/include/kernel/filesystem/open_file_descriptor.hpp
index 823fe13..7ca7350 100644
--- a/kernel/include/kernel/filesystem/open_file_descriptor.hpp
+++ b/kernel/include/kernel/filesystem/open_file_descriptor.hpp
@@ -50,7 +50,13 @@ namespace kernel::filesystem
     @brief Returns the current file offset for this open file descriptor.
     @return The current file offset in bytes.
      */
-    [[nodiscard]] auto offset() const -> size_t;
+    [[nodiscard]] auto get_offset() const -> size_t;
+
+    /**
+    @brief Return a reference to the dentry associated with this open file descriptor.
+    @return A reference to the associated dentry.
+     */
+    [[nodiscard]] auto get_dentry() const -> kstd::shared_ptr<dentry> const &;
 
   private:
     kstd::shared_ptr<dentry> m_dentry;
diff --git a/kernel/include/kernel/filesystem/vfs.hpp b/kernel/include/kernel/filesystem/vfs.hpp
index 7e2eae7..48b99b2 100644
--- a/kernel/include/kernel/filesystem/vfs.hpp
+++ b/kernel/include/kernel/filesystem/vfs.hpp
@@ -33,6 +33,7 @@ namespace kernel::filesystem
       mount_point_not_found = -3,
       unmount_failed = -4,
       invalid_filesystem = -5,
+      close_failed = -6
     };
 
     /**
@@ -60,6 +61,13 @@ namespace kernel::filesystem
     */
     auto open(std::string_view path) -> kstd::shared_ptr<dentry>;
 
+    /**
+    @brief Close a file by its associated @p dentry.
+    @param dentry The dentry of the file to close.
+    @return The result of the close operation.
+    */
+    auto close(kstd::shared_ptr<dentry> const & dentry) -> operation_result;
+
     /**
     @brief Mount a @p source path to a specific @p target path.
     @param source The source of the filesystem to mount.
-- 
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