feat: initial shared file page management and initialization

src/vm/page.h

@@ -5,13 +5,16 @@
 #include "threads/synch.h"
 #include "filesys/off_t.h"
 
-enum page_type {
+enum page_type
+{
   PAGE_FILE,
   PAGE_MMAP,
-  PAGE_EMPTY
+  PAGE_EMPTY,
+  PAGE_SHARED
 };
 
-struct page_entry {
+struct page_entry
+{
   enum page_type type; /* Type of Data that should go into the page */
   void *upage;         /* Start Address of the User Page (Key of hash table). */
 
@@ -30,6 +33,17 @@ struct page_entry {
   struct hash_elem elem; /* An elem for the hash table. */
 };
 
+struct shared_file_page
+{
+  struct file *file;
+  void *upage;
+  void *frame;
+  size_t swap_slot;
+  int ref_count;
+
+  struct hash_elem elem;
+};
+
 bool init_pages (struct hash *pages);
 struct page_entry *page_insert_swapped (void *upage, void* kpage,
                                         struct thread *owner);
@@ -41,6 +55,11 @@ bool page_load_file (struct page_entry *page);
 void page_cleanup (struct hash_elem *e, void *aux);
 
 bool page_in_swap (struct thread *, void *);
+bool page_in_swap_pte (uint32_t *pte);
 size_t page_get_swap (struct thread *owner, void *upage);
+size_t page_get_swap_pte (uint32_t *pte);
 
-#endif /* vm/frame.h */
+bool page_is_shared_pte (uint32_t *pte);
+void shared_file_pages_init ();
+
+#endif