Kernel: Add a mode flag to sys$purge and allow purging clean inodes

Kernel/Process.cpp

@@ -404,20 +404,36 @@ int Process::sys$madvise(void* address, size_t size, int advice)
  return -EINVAL;
 }
 
-int Process::sys$purge()
+int Process::sys$purge(int mode)
 {
- NonnullRefPtrVector<PurgeableVMObject> vmobjects;
- {
- InterruptDisabler disabler;
- MM.for_each_vmobject([&](auto& vmobject) {
- if (vmobject.is_purgeable())
- vmobjects.append(static_cast<PurgeableVMObject&>(vmobject));
- return IterationDecision::Continue;
- });
- }
  int purged_page_count = 0;
- for (auto& vmobject : vmobjects) {
- purged_page_count += vmobject.purge();
+ if (mode & PURGE_ALL_VOLATILE) {
+ NonnullRefPtrVector<PurgeableVMObject> vmobjects;
+ {
+ InterruptDisabler disabler;
+ MM.for_each_vmobject([&](auto& vmobject) {
+ if (vmobject.is_purgeable())
+ vmobjects.append(static_cast<PurgeableVMObject&>(vmobject));
+ return IterationDecision::Continue;
+ });
+ }
+ for (auto& vmobject : vmobjects) {
+ purged_page_count += vmobject.purge();
+ }
+ }
+ if (mode & PURGE_ALL_CLEAN_INODE) {
+ NonnullRefPtrVector<InodeVMObject> vmobjects;
+ {
+ InterruptDisabler disabler;
+ MM.for_each_vmobject([&](auto& vmobject) {
+ if (vmobject.is_inode())
+ vmobjects.append(static_cast<InodeVMObject&>(vmobject));
+ return IterationDecision::Continue;
+ });
+ }
+ for (auto& vmobject : vmobjects) {
+ purged_page_count += vmobject.release_all_clean_pages();
+ }
  }
  return purged_page_count;
 }

Kernel/Process.h

@@ -142,7 +142,7 @@ class Process : public InlineLinkedListNode<Process>
  int sys$set_mmap_name(void*, size_t, const char*);
  int sys$mprotect(void*, size_t, int prot);
  int sys$madvise(void*, size_t, int advice);
- int sys$purge();
+ int sys$purge(int mode);
  int sys$select(const Syscall::SC_select_params*);
  int sys$poll(pollfd*, int nfds, int timeout);
  ssize_t sys$get_dir_entries(int fd, void*, ssize_t);

Kernel/UnixTypes.h

@@ -467,3 +467,5 @@ struct ifreq {
 
 #define AT_FDCWD -100
 
+#define PURGE_ALL_VOLATILE 0x1
+#define PURGE_ALL_CLEAN_INODE 0x2

Kernel/VM/InodeVMObject.cpp

@@ -39,7 +39,8 @@ InodeVMObject::~InodeVMObject()
 size_t InodeVMObject::amount_clean() const
 {
  size_t count = 0;
- for (int i = 0; i < m_dirty_pages.size(); ++i) {
+ 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;
  }
@@ -125,3 +126,25 @@ void InodeVMObject::inode_contents_changed(Badge<Inode>, off_t offset, ssize_t s
  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;
+}

Kernel/VM/InodeVMObject.h

@@ -19,6 +19,8 @@ class InodeVMObject final : public VMObject {
  size_t amount_dirty() const;
  size_t amount_clean() const;
 
+ int release_all_clean_pages();
+
 private:
  explicit InodeVMObject(Inode&);
  explicit InodeVMObject(const InodeVMObject&);
@@ -29,6 +31,8 @@ class InodeVMObject final : public VMObject {
 
  virtual bool is_inode() const override { return true; }
 
+ int release_all_clean_pages_impl();
+
  NonnullRefPtr<Inode> m_inode;
  Bitmap m_dirty_pages;
 };

Kernel/VM/Region.cpp

@@ -410,6 +410,10 @@ PageFaultResponse Region::handle_inode_fault(size_t page_index_in_region)
  LOCKER(vmobject().m_paging_lock);
  cli();
 
+#ifdef PAGE_FAULT_DEBUG
+ dbg() << *current << " inode fault in " << name() << " page index: " << page_index_in_region;
+#endif
+
  if (!vmobject_physical_page_entry.is_null()) {
 #ifdef PAGE_FAULT_DEBUG
  dbgprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");

Userland/purge.cpp

@@ -1,9 +1,26 @@
-#include <stdio.h>
 #include <Kernel/Syscall.h>
+#include <stdio.h>
+#include <string.h>
+
+#define PURGE_ALL_VOLATILE 0x1
+#define PURGE_ALL_CLEAN_INODE 0x2
 
-int main(int, char**)
+int main(int argc, char** argv)
 {
- int purged_page_count = syscall(SC_purge);
+ int mode = 0;
+ if (argc == 1) {
+ mode = PURGE_ALL_VOLATILE | PURGE_ALL_CLEAN_INODE;
+ } else {
+ if (!strcmp(argv[1], "-c")) {
+ mode = PURGE_ALL_CLEAN_INODE;
+ } else if (!strcmp(argv[1], "-v")) {
+ mode = PURGE_ALL_VOLATILE;
+ } else {
+ fprintf(stderr, "Unknown option: %s\n", argv[1]);
+ return 1;
+ }
+ }
+ int purged_page_count = syscall(SC_purge, mode);
  printf("Purged page count: %d\n", purged_page_count);
  return 0;
 }