Mount can only be unmounted if no references are present, increment references on open file and decrement on close file

10 files changed, 104 insertions, 19 deletions

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
     };
 
     /**
@@ -61,6 +62,13 @@ 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.
     @param target The path where the filesystem should be mounted.
diff --git a/kernel/kapi/filesystem.cpp b/kernel/kapi/filesystem.cpp
index 77d7eb0..1782da5 100644
--- a/kernel/kapi/filesystem.cpp
+++ b/kernel/kapi/filesystem.cpp
@@ -44,7 +44,15 @@ namespace kapi::filesystem
 
   auto close(int file_descriptor) -> int
   {
-    return kernel::filesystem::open_file_table::get().remove_file(file_descriptor);
+    if (auto open_file_descriptor = kernel::filesystem::open_file_table::get().get_file(file_descriptor))
+    {
+      if (kernel::filesystem::vfs::get().close(open_file_descriptor->get_dentry()) ==
+          kernel::filesystem::vfs::operation_result::success)
+      {
+        return kernel::filesystem::open_file_table::get().remove_file(file_descriptor);
+      }
+    }
+    return -1;
   }
 
   auto read(int file_descriptor, void * buffer, size_t size) -> ssize_t
diff --git a/kernel/src/filesystem/mount.cpp b/kernel/src/filesystem/mount.cpp
index 749c86a..3016509 100644
--- a/kernel/src/filesystem/mount.cpp
+++ b/kernel/src/filesystem/mount.cpp
@@ -18,6 +18,7 @@ namespace kernel::filesystem
       , m_root_dentry(root_dentry)
       , m_filesystem(fs)
       , m_parent_mount(parent_mount)
+      , m_ref_count(0)
   {
     if (!m_filesystem)
     {
@@ -53,4 +54,25 @@ namespace kernel::filesystem
   {
     return m_parent_mount;
   }
+
+  auto mount::increment_ref_count() -> void
+  {
+    m_ref_count += 1;
+  }
+
+  auto mount::decrement_ref_count() -> bool
+  {
+    if (m_ref_count == 0)
+    {
+      return false;
+    }
+
+    m_ref_count -= 1;
+    return true;
+  }
+
+  auto mount::is_ready_to_unmount() const -> bool
+  {
+    return m_ref_count == 0;
+  }
 }  // namespace kernel::filesystem
\ No newline at end of file
diff --git a/kernel/src/filesystem/mount_table.cpp b/kernel/src/filesystem/mount_table.cpp
index b582fd9..9951590 100644
--- a/kernel/src/filesystem/mount_table.cpp
+++ b/kernel/src/filesystem/mount_table.cpp
@@ -30,7 +30,6 @@ namespace kernel::filesystem
 
   auto mount_table::remove_mount(std::string_view path) -> operation_result
   {
-    // TODO BA-FS26 check wheter something is open in this mount
     auto mount_it = find_mount_iterator(path);
     if (mount_it == m_mounts.end())
     {
@@ -38,6 +37,10 @@ namespace kernel::filesystem
     }
 
     auto const & mount = *mount_it;
+    if (!mount->is_ready_to_unmount())
+    {
+      return operation_result::cannot_be_unmounted;
+    }
     if (has_child_mounts(mount))
     {
       return operation_result::has_child_mounts;
diff --git a/kernel/src/filesystem/open_file_descriptor.cpp b/kernel/src/filesystem/open_file_descriptor.cpp
index 27e6449..ebaabef 100644
--- a/kernel/src/filesystem/open_file_descriptor.cpp
+++ b/kernel/src/filesystem/open_file_descriptor.cpp
@@ -33,9 +33,14 @@ namespace kernel::filesystem
     return written_bytes;
   }
 
-  auto open_file_descriptor::offset() const -> size_t
+  auto open_file_descriptor::get_offset() const -> size_t
   {
     return m_offset;
   }
 
+  auto open_file_descriptor::get_dentry() const -> kstd::shared_ptr<dentry> const &
+  {
+    return m_dentry;
+  }
+
 }  // namespace kernel::filesystem
\ No newline at end of file
diff --git a/kernel/src/filesystem/open_file_descriptor.tests.cpp b/kernel/src/filesystem/open_file_descriptor.tests.cpp
index 8c24cf0..1910b8b 100644
--- a/kernel/src/filesystem/open_file_descriptor.tests.cpp
+++ b/kernel/src/filesystem/open_file_descriptor.tests.cpp
@@ -26,7 +26,7 @@ SCENARIO("Open file descriptor construction", "[filesystem][open_file_descriptor
 
     THEN("the initial offset is zero")
     {
-      REQUIRE(file_descriptor.offset() == 0);
+      REQUIRE(file_descriptor.get_offset() == 0);
     }
   }
 }
@@ -42,29 +42,29 @@ SCENARIO("Open file descriptor read/write offset management", "[filesystem][open
     THEN("the offset is updated correctly after reads")
     {
       REQUIRE(file_descriptor.read(nullptr, 100) == 100);
-      REQUIRE(file_descriptor.offset() == 100);
+      REQUIRE(file_descriptor.get_offset() == 100);
       REQUIRE(file_descriptor.read(nullptr, 50) == 50);
-      REQUIRE(file_descriptor.offset() == 150);
+      REQUIRE(file_descriptor.get_offset() == 150);
     }
 
     THEN("the offset is updated correctly after writes")
     {
       REQUIRE(file_descriptor.write(nullptr, 200) == 200);
-      REQUIRE(file_descriptor.offset() == 200);
+      REQUIRE(file_descriptor.get_offset() == 200);
       REQUIRE(file_descriptor.write(nullptr, 25) == 25);
-      REQUIRE(file_descriptor.offset() == 225);
+      REQUIRE(file_descriptor.get_offset() == 225);
     }
 
     THEN("reads and writes both update the same offset")
     {
       REQUIRE(file_descriptor.read(nullptr, 10) == 10);
-      REQUIRE(file_descriptor.offset() == 10);
+      REQUIRE(file_descriptor.get_offset() == 10);
       REQUIRE(file_descriptor.write(nullptr, 20) == 20);
-      REQUIRE(file_descriptor.offset() == 30);
+      REQUIRE(file_descriptor.get_offset() == 30);
       REQUIRE(file_descriptor.read(nullptr, 5) == 5);
-      REQUIRE(file_descriptor.offset() == 35);
+      REQUIRE(file_descriptor.get_offset() == 35);
       REQUIRE(file_descriptor.write(nullptr, 15) == 15);
-      REQUIRE(file_descriptor.offset() == 50);
+      REQUIRE(file_descriptor.get_offset() == 50);
     }
   }
 }
@@ -89,7 +89,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "Ope
       kstd::vector<std::byte> buffer(32);
       auto bytes_read = ofd->read(buffer.data(), buffer.size());
       REQUIRE(bytes_read == 7);
-      REQUIRE(ofd->offset() == 7);
+      REQUIRE(ofd->get_offset() == 7);
 
       std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), static_cast<size_t>(bytes_read)};
       REQUIRE(buffer_as_str == "info_1\n");
@@ -100,11 +100,11 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "Ope
       kstd::vector<std::byte> buffer(4);
       auto bytes_read_1 = ofd->read(buffer.data(), buffer.size() / 2);
       REQUIRE(bytes_read_1 == buffer.size() / 2);
-      REQUIRE(ofd->offset() == buffer.size() / 2);
+      REQUIRE(ofd->get_offset() == buffer.size() / 2);
 
       auto bytes_read_2 = ofd->read(buffer.data() + buffer.size() / 2, buffer.size() / 2);
       REQUIRE(bytes_read_2 == buffer.size() / 2);
-      REQUIRE(ofd->offset() == buffer.size());
+      REQUIRE(ofd->get_offset() == buffer.size());
 
       std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), bytes_read_1 + bytes_read_2};
       REQUIRE(buffer_as_str == "info");
diff --git a/kernel/src/filesystem/vfs.cpp b/kernel/src/filesystem/vfs.cpp
index 77ae015..3b3d6ff 100644
--- a/kernel/src/filesystem/vfs.cpp
+++ b/kernel/src/filesystem/vfs.cpp
@@ -89,7 +89,22 @@ namespace kernel::filesystem
 
   auto vfs::open(std::string_view path) -> kstd::shared_ptr<dentry>
   {
-    return resolve_path(path);
+    auto [dentry, mount] = resolve_path_internal(path);
+    mount->increment_ref_count();
+    return dentry;
+  }
+
+  auto vfs::close(kstd::shared_ptr<dentry> const & dentry) -> operation_result
+  {
+    if (auto mount = find_mount(dentry->get_absolute_path().view()))
+    {
+      if (mount->decrement_ref_count())
+      {
+        return operation_result::success;
+      }
+      return operation_result::close_failed;
+    }
+    return operation_result::invalid_path;
   }
 
   auto vfs::do_mount(std::string_view source, std::string_view target) -> operation_result