Merge branch 'mount-reference-count' into 'develop-BA-FS26'

Mount reference count

See merge request teachos/kernel!37

1 files changed, 42 insertions, 0 deletions

diff --git a/kernel/src/filesystem/mount.tests.cpp b/kernel/src/filesystem/mount.tests.cpp
index 58e9bab..e7dd709 100644
--- a/kernel/src/filesystem/mount.tests.cpp
+++ b/kernel/src/filesystem/mount.tests.cpp
@@ -29,6 +29,7 @@ SCENARIO("Mount construction", "[filesystem][mount]")
         REQUIRE(mount.get_root_dentry() == root_dentry);
         REQUIRE(mount.get_mount_dentry() == root_dentry);
         REQUIRE(mount.get_mount_path() == "/");
+        REQUIRE(mount.is_ready_to_unmount());
       }
 
       THEN("the mount has no parent mount")
@@ -47,3 +48,44 @@ SCENARIO("Mount construction", "[filesystem][mount]")
     }
   }
 }
+
+SCENARIO("Mount reference counting", "[filesystem][mount]")
+{
+  GIVEN("a filesystem and a root dentry")
+  {
+    auto fs = kstd::make_shared<kernel::tests::filesystem::filesystem>();
+    auto root_inode = kstd::make_shared<kernel::tests::filesystem::inode>();
+    auto root_dentry = kstd::make_shared<kernel::filesystem::dentry>(nullptr, root_inode, "/");
+
+    THEN("reference count can be incremented and decremented, the mount is ready to unmount when the reference "
+         "count == 0")
+    {
+      auto mount = kernel::filesystem::mount{root_dentry, root_dentry, fs, nullptr};
+
+      mount.increment_ref_count();
+      REQUIRE(mount.get_ref_count() == 1);
+      REQUIRE_FALSE(mount.is_ready_to_unmount());
+
+      mount.increment_ref_count();
+      REQUIRE(mount.get_ref_count() == 2);
+      REQUIRE_FALSE(mount.is_ready_to_unmount());
+
+      REQUIRE(mount.decrement_ref_count());
+      REQUIRE(mount.get_ref_count() == 1);
+      REQUIRE_FALSE(mount.is_ready_to_unmount());
+
+      REQUIRE(mount.decrement_ref_count());
+      REQUIRE(mount.get_ref_count() == 0);
+      REQUIRE(mount.is_ready_to_unmount());
+    }
+
+    THEN("decrementing reference count when it is already zero does not decrement it below zero")
+    {
+      auto mount = kernel::filesystem::mount{root_dentry, root_dentry, fs, nullptr};
+
+      REQUIRE_FALSE(mount.decrement_ref_count());
+      REQUIRE(mount.get_ref_count() == 0);
+      REQUIRE(mount.is_ready_to_unmount());
+    }
+  }
+}
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