Kernel+LibC: Implement fsync

Kernel/FileSystem/File.h

@@ -96,6 +96,7 @@ public:
     virtual String absolute_path(const OpenFileDescription&) const = 0;
 
     virtual KResult truncate(u64) { return EINVAL; }
+    virtual KResult sync() { return EINVAL; }
     virtual KResult chown(OpenFileDescription&, UserID, GroupID) { return EBADF; }
     virtual KResult chmod(OpenFileDescription&, mode_t) { return EBADF; }
 

Kernel/FileSystem/FileSystem.cpp

@@ -51,7 +51,7 @@ FileSystem::DirectoryEntryView::DirectoryEntryView(const StringView& n, InodeIde
 
 void FileSystem::sync()
 {
-    Inode::sync();
+    Inode::sync_all();
 
     NonnullRefPtrVector<FileSystem, 32> file_systems;
     {

Kernel/FileSystem/Inode.cpp

@@ -29,7 +29,7 @@ SpinlockProtected<Inode::AllInstancesList>& Inode::all_instances()
     return s_all_instances;
 }
 
-void Inode::sync()
+void Inode::sync_all()
 {
     NonnullRefPtrVector<Inode, 32> inodes;
     Inode::all_instances().with([&](auto& all_inodes) {
@@ -45,6 +45,13 @@ void Inode::sync()
     }
 }
 
+void Inode::sync()
+{
+    if (is_metadata_dirty())
+        flush_metadata();
+    fs().flush_writes();
+}
+
 KResultOr<NonnullOwnPtr<KBuffer>> Inode::read_entire(OpenFileDescription* description) const
 {
     auto builder = TRY(KBufferBuilder::try_create());

Kernel/FileSystem/Inode.h

@@ -87,7 +87,8 @@ public:
     void set_shared_vmobject(Memory::SharedInodeVMObject&);
     RefPtr<Memory::SharedInodeVMObject> shared_vmobject() const;
 
-    static void sync();
+    static void sync_all();
+    void sync();
 
     bool has_watchers() const { return !m_watchers.is_empty(); }
 

Kernel/FileSystem/InodeFile.cpp

@@ -107,6 +107,12 @@ KResult InodeFile::truncate(u64 size)
     return KSuccess;
 }
 
+KResult InodeFile::sync()
+{
+    m_inode->sync();
+    return KSuccess;
+}
+
 KResult InodeFile::chown(OpenFileDescription& description, UserID uid, GroupID gid)
 {
     VERIFY(description.inode() == m_inode);

Kernel/FileSystem/InodeFile.h

@@ -39,6 +39,7 @@ public:
     virtual String absolute_path(const OpenFileDescription&) const override;
 
     virtual KResult truncate(u64) override;
+    virtual KResult sync() override;
     virtual KResult chown(OpenFileDescription&, UserID, GroupID) override;
     virtual KResult chmod(OpenFileDescription&, mode_t) override;
 

Kernel/FileSystem/OpenFileDescription.cpp

@@ -383,6 +383,12 @@ KResult OpenFileDescription::truncate(u64 length)
     return m_file->truncate(length);
 }
 
+KResult OpenFileDescription::sync()
+{
+    MutexLocker locker(m_lock);
+    return m_file->sync();
+}
+
 bool OpenFileDescription::is_fifo() const
 {
     return m_file->is_fifo();

Kernel/FileSystem/OpenFileDescription.h

@@ -122,6 +122,7 @@ public:
     void set_original_custody(Badge<VirtualFileSystem>, Custody& custody);
 
     KResult truncate(u64);
+    KResult sync();
 
     off_t offset() const { return m_current_offset; }