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

5 files changed, 60 insertions, 15 deletions

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