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

Increase reference count of source_mount when one of its files is mounted somewhere

See merge request teachos/kernel!42

1 files changed, 34 insertions, 7 deletions

diff --git a/kernel/src/filesystem/mount_table.tests.cpp b/kernel/src/filesystem/mount_table.tests.cpp
index f22b25e..19b47b2 100644
--- a/kernel/src/filesystem/mount_table.tests.cpp
+++ b/kernel/src/filesystem/mount_table.tests.cpp
@@ -38,14 +38,14 @@ SCENARIO("Adding, finding and removing mounts in the mount table", "[filesystem]
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
-    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr);
+    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr, nullptr);
 
     auto fs2 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
     auto root_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/mnt");
-    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, nullptr);
+    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, nullptr, nullptr);
 
     table.add_mount(mount1);
     table.add_mount(mount2);
@@ -89,14 +89,14 @@ SCENARIO("Adding, finding and removing mounts in the mount table", "[filesystem]
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
-    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr);
+    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr, nullptr);
 
     auto fs2 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
     auto root_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
-    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, nullptr);
+    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, nullptr, nullptr);
 
     table.add_mount(mount1);
     table.add_mount(mount2);
@@ -122,21 +122,21 @@ SCENARIO("Adding, finding and removing mounts in the mount table", "[filesystem]
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry1 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
-    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr);
+    auto mount1 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry1, root_dentry1, fs1, nullptr, nullptr);
 
     auto fs2 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
     auto root_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry2 = kstd::make_shared<kernel::filesystem::dentry>(
         mount_dentry1, kstd::make_shared<kernel::tests::filesystem::inode>(), "mnt");
-    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, mount1);
+    auto mount2 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry2, root_dentry2, fs2, mount1, nullptr);
 
     auto fs3 = kstd::make_shared<kernel::tests::filesystem::filesystem>();
     auto root_dentry3 = kstd::make_shared<kernel::filesystem::dentry>(
         nullptr, kstd::make_shared<kernel::tests::filesystem::inode>(), "/");
     auto mount_dentry3 = kstd::make_shared<kernel::filesystem::dentry>(
         mount_dentry2, kstd::make_shared<kernel::tests::filesystem::inode>(), "submnt");
-    auto mount3 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry3, root_dentry3, fs3, mount2);
+    auto mount3 = kstd::make_shared<kernel::filesystem::mount>(mount_dentry3, root_dentry3, fs3, mount2, nullptr);
 
     table.add_mount(mount1);
     table.add_mount(mount2);
@@ -155,3 +155,30 @@ SCENARIO("Adding, finding and removing mounts in the mount table", "[filesystem]
     }
   }
 }
+
+SCENARIO("Mount reference counting", "[filesystem][mount_table]")
+{
+  kernel::filesystem::mount_table table;
+
+  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, "/");
+
+    auto source_mount = kstd::make_shared<kernel::filesystem::mount>(root_dentry, root_dentry, fs, nullptr, nullptr);
+    auto mount = kstd::make_shared<kernel::filesystem::mount>(root_dentry, root_dentry, fs, nullptr, source_mount);
+
+    THEN("reference count of source mount is incremented when a mount is added to the mount table and decremented when "
+         "the mount is removed")
+    {
+      REQUIRE(source_mount->ref_count() == 0);
+
+      table.add_mount(mount);
+      REQUIRE(source_mount->ref_count() == 1);
+
+      REQUIRE(table.remove_mount("/") == kernel::filesystem::mount_table::operation_result::removed);
+      REQUIRE(source_mount->ref_count() == 0);
+    }
+  }
+}