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Kernel: Don't rewrite the whole file on sys$msync

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Hendiadyoin1 2021-11-18 15:54:39 +01:00 • committed by Andreas Kling
parent 259f78545a
commit c7b90fa7d3
3 changed files with 10 additions and 4 deletions
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6
Kernel/Memory/SharedInodeVMObject.cpp
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@ -35,11 +35,13 @@ SharedInodeVMObject::SharedInodeVMObject(SharedInodeVMObject const& other)
{
}
ErrorOr<void> SharedInodeVMObject::sync()
ErrorOr<void> SharedInodeVMObject::sync(off_t offset_in_pages, size_t pages)
{
SpinlockLocker locker(m_lock);
for (size_t page_index = 0; page_index < page_count(); ++page_index) {
size_t highest_page_to_flush = min(page_count(), offset_in_pages + pages);
for (size_t page_index = offset_in_pages; page_index < highest_page_to_flush; ++page_index) {
auto& physical_page = m_physical_pages[page_index];
if (!physical_page)
continue;

2
Kernel/Memory/SharedInodeVMObject.h
View file

@ -18,7 +18,7 @@ public:
static ErrorOr<NonnullRefPtr<SharedInodeVMObject>> try_create_with_inode(Inode&);
virtual ErrorOr<NonnullRefPtr<VMObject>> try_clone() override;
ErrorOr<void> sync();
ErrorOr<void> sync(off_t offset_in_pages = 0, size_t pages = -1);
private:
virtual bool is_shared_inode() const override { return true; }

6
Kernel/Syscalls/mmap.cpp
View file

@ -616,8 +616,12 @@ ErrorOr<FlatPtr> Process::sys$msync(Userspace<void*> address, size_t size, int f
if (!vmobject.is_shared_inode())
return 0;
off_t offset = region->offset_in_vmobject() + address.ptr() - region->range().base().get();
auto& inode_vmobject = static_cast<Memory::SharedInodeVMObject&>(vmobject);
TRY(inode_vmobject.sync());
// FIXME: Handle MS_ASYNC
TRY(inode_vmobject.sync(offset / PAGE_SIZE, size / PAGE_SIZE));
// FIXME: Handle MS_INVALIDATE
// FIXME: If msync() causes any write to a file, the file's st_ctime and st_mtime fields shall be marked for update.
return 0;
}