Merge branch 'vm/mmap-write-back-on-eviction' into 'vm/virtual-memory/themis-synch'

Write back mmap file pages to file upon eviction

See merge request lab2425_autumn/pintos_22!59

src/userprog/exception.c

@@ -252,7 +252,7 @@ fetch_page (void *upage, bool write)
 {
   /* Check if the page is in the supplemental page table. That is, it is a page
      that is expected to be in memory. */
-  struct page_entry *page = page_get (upage);
+  struct page_entry *page = page_get (thread_current (), upage);
   if (page == NULL)
     return false;
 

src/userprog/syscall.c

@@ -462,7 +462,7 @@ syscall_mmap (int fd, void *addr)
      hold the entire file. */
   for (off_t ofs = 0; ofs < file_size; ofs += PGSIZE)
     {
-      if (page_get (addr + ofs) != NULL)
+      if (page_get (thread_current (), addr + ofs) != NULL)
         return MMAP_FAILURE;
     }
 

src/vm/frame.c

@@ -2,12 +2,13 @@
 #include <hash.h>
 #include <list.h>
 #include <string.h>
-
 #include "frame.h"
 #include "page.h"
+#include "filesys/file.h"
 #include "threads/malloc.h"
 #include "threads/vaddr.h"
 #include "userprog/pagedir.h"
+#include "userprog/syscall.h"
 #include "threads/synch.h"
 
 /* Hash table that maps every active frame's kernel virtual address
@@ -94,8 +95,25 @@ frame_alloc (enum palloc_flags flags, void *upage, struct thread *owner)
       struct frame_metadata *victim = get_victim ();
       ASSERT (victim != NULL); /* get_victim () should never return null. */
 
-      /* 2. Swap out victim into disk. */
-      page_insert_swapped (victim->upage, victim->frame, victim->owner);
+      /* 2. Handle victim page writing based on its type. */
+      struct page_entry *victim_page = page_get (victim->upage);
+      if (victim_page != NULL && victim_page->type == PAGE_MMAP)
+        {
+          /* If it was a memory-mapped file page, we just write it back
+             to the file if it was dirty. */
+          if (pagedir_is_dirty(owner->pagedir, victim->upage))
+            {
+              lock_acquire (&filesys_lock);
+              file_write_at (victim_page->file, victim->upage,
+                             victim_page->read_bytes, victim_page->offset);
+              lock_release (&filesys_lock);
+            }
+
+        }
+      else
+        /* Otherwise, insert the page into swap. */
+        page_insert_swapped (victim->upage, victim->frame, victim->owner);
+
 
       /* If zero flag is set, zero out the victim page. */
       if (flags & PAL_ZERO)

src/vm/mmap.c

@@ -1,5 +1,6 @@
 #include "mmap.h"
 #include "page.h"
+#include "threads/thread.h"
 #include "threads/vaddr.h"
 #include "threads/malloc.h"
 #include "userprog/syscall.h"
@@ -70,7 +71,7 @@ mmap_unmap (struct mmap_entry *mmap)
     void *upage = mmap->upage + ofs;
 
     /* Get the SPT page entry for this page. */
-    struct page_entry *page = page_get(upage);
+    struct page_entry *page = page_get(thread_current (), upage);
     if (page == NULL)
       continue;
 

src/vm/page.c

@@ -47,7 +47,7 @@ struct page_entry *
 page_insert_swapped (void *upage, void *kpage, struct thread *owner)
 {
   /* 1. Initialize swapped page entry. */
-  struct page_entry *page = page_get (upage);
+  struct page_entry *page = page_get (thread_current (), upage);
   if (page == NULL)
     {
       page = malloc (sizeof (struct page_entry));
@@ -103,13 +103,13 @@ page_insert_file (struct file *file, off_t ofs, void *upage,
 /* Gets a page_entry from the starting address of the page. Returns NULL if no
    such page_entry exists in the hash map.*/
 struct page_entry *
-page_get (void *upage)
+page_get (struct thread *thread, void *upage)
 {
   struct page_entry fake_page_entry;
   fake_page_entry.upage = upage;
 
   struct hash_elem *e
-    = hash_find (&thread_current ()->pages, &fake_page_entry.elem);
+    = hash_find (&thread->pages, &fake_page_entry.elem);
   if (e == NULL)
       return NULL;
 

src/vm/page.h

@@ -37,7 +37,7 @@ struct page_entry *page_insert_swapped (void *upage, void* kpage,
 struct page_entry *page_insert_file (struct file *file, off_t ofs, void *upage,
                                      uint32_t read_bytes, uint32_t zero_bytes,
                                      bool writable, enum page_type);
-struct page_entry *page_get (void *upage);
+struct page_entry *page_get (struct thread *thread, void *upage);
 bool page_load_file (struct page_entry *page, bool writable);
 void page_cleanup (struct hash_elem *e, void *aux);