Kernel: Split InodeVMObject into two subclasses

We now have PrivateInodeVMObject and SharedInodeVMObject, corresponding
to MAP_PRIVATE and MAP_SHARED respectively.

Note that PrivateInodeVMObject is not used yet.

Kernel/VM/InodeVMObject.cpp

@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <Kernel/FileSystem/Inode.h>
+#include <Kernel/VM/InodeVMObject.h>
+#include <Kernel/VM/MemoryManager.h>
+#include <Kernel/VM/Region.h>
+
+namespace Kernel {
+
+InodeVMObject::InodeVMObject(Inode& inode, size_t size)
+    : VMObject(size)
+    , m_inode(inode)
+    , m_dirty_pages(page_count(), false)
+{
+}
+
+InodeVMObject::InodeVMObject(const InodeVMObject& other)
+    : VMObject(other)
+    , m_inode(other.m_inode)
+{
+}
+
+InodeVMObject::~InodeVMObject()
+{
+}
+
+size_t InodeVMObject::amount_clean() const
+{
+    size_t count = 0;
+    ASSERT(page_count() == (size_t)m_dirty_pages.size());
+    for (size_t i = 0; i < page_count(); ++i) {
+        if (!m_dirty_pages.get(i) && m_physical_pages[i])
+            ++count;
+    }
+    return count * PAGE_SIZE;
+}
+
+size_t InodeVMObject::amount_dirty() const
+{
+    size_t count = 0;
+    for (size_t i = 0; i < m_dirty_pages.size(); ++i) {
+        if (m_dirty_pages.get(i))
+            ++count;
+    }
+    return count * PAGE_SIZE;
+}
+
+void InodeVMObject::inode_size_changed(Badge<Inode>, size_t old_size, size_t new_size)
+{
+    dbg() << "VMObject::inode_size_changed: {" << m_inode->fsid() << ":" << m_inode->index() << "} " << old_size << " -> " << new_size;
+
+    InterruptDisabler disabler;
+
+    auto new_page_count = PAGE_ROUND_UP(new_size) / PAGE_SIZE;
+    m_physical_pages.resize(new_page_count);
+
+    m_dirty_pages.grow(new_page_count, false);
+
+    // FIXME: Consolidate with inode_contents_changed() so we only do a single walk.
+    for_each_region([](auto& region) {
+        region.remap();
+    });
+}
+
+void InodeVMObject::inode_contents_changed(Badge<Inode>, off_t offset, ssize_t size, const u8* data)
+{
+    (void)size;
+    (void)data;
+    InterruptDisabler disabler;
+    ASSERT(offset >= 0);
+
+    // FIXME: Only invalidate the parts that actually changed.
+    for (auto& physical_page : m_physical_pages)
+        physical_page = nullptr;
+
+#if 0
+    size_t current_offset = offset;
+    size_t remaining_bytes = size;
+    const u8* data_ptr = data;
+
+    auto to_page_index = [] (size_t offset) -> size_t {
+        return offset / PAGE_SIZE;
+    };
+
+    if (current_offset & PAGE_MASK) {
+        size_t page_index = to_page_index(current_offset);
+        size_t bytes_to_copy = min(size, PAGE_SIZE - (current_offset & PAGE_MASK));
+        if (m_physical_pages[page_index]) {
+            auto* ptr = MM.quickmap_page(*m_physical_pages[page_index]);
+            memcpy(ptr, data_ptr, bytes_to_copy);
+            MM.unquickmap_page();
+        }
+        current_offset += bytes_to_copy;
+        data += bytes_to_copy;
+        remaining_bytes -= bytes_to_copy;
+    }
+
+    for (size_t page_index = to_page_index(current_offset); page_index < m_physical_pages.size(); ++page_index) {
+        size_t bytes_to_copy = PAGE_SIZE - (current_offset & PAGE_MASK);
+        if (m_physical_pages[page_index]) {
+            auto* ptr = MM.quickmap_page(*m_physical_pages[page_index]);
+            memcpy(ptr, data_ptr, bytes_to_copy);
+            MM.unquickmap_page();
+        }
+        current_offset += bytes_to_copy;
+        data += bytes_to_copy;
+    }
+#endif
+
+    // FIXME: Consolidate with inode_size_changed() so we only do a single walk.
+    for_each_region([](auto& region) {
+        region.remap();
+    });
+}
+
+int InodeVMObject::release_all_clean_pages()
+{
+    LOCKER(m_paging_lock);
+    return release_all_clean_pages_impl();
+}
+
+int InodeVMObject::release_all_clean_pages_impl()
+{
+    int count = 0;
+    InterruptDisabler disabler;
+    for (size_t i = 0; i < page_count(); ++i) {
+        if (!m_dirty_pages.get(i) && m_physical_pages[i]) {
+            m_physical_pages[i] = nullptr;
+            ++count;
+        }
+    }
+    for_each_region([](auto& region) {
+        region.remap();
+    });
+    return count;
+}
+
+u32 InodeVMObject::writable_mappings() const
+{
+    u32 count = 0;
+    const_cast<InodeVMObject&>(*this).for_each_region([&](auto& region) {
+        if (region.is_writable())
+            ++count;
+    });
+    return count;
+}
+
+u32 InodeVMObject::executable_mappings() const
+{
+    u32 count = 0;
+    const_cast<InodeVMObject&>(*this).for_each_region([&](auto& region) {
+        if (region.is_executable())
+            ++count;
+    });
+    return count;
+}
+
+}