Implement implicitly unmapping all mmapped files when a process exits. Refactor to reduce duplication

src/vm/mmap.c

@@ -4,6 +4,7 @@
 #include "threads/malloc.h"
 #include "userprog/syscall.h"
 #include "userprog/pagedir.h"
+#include <stdio.h>
 
 static unsigned mmap_hash (const struct hash_elem *e, void *aux);
 static bool mmap_less (const struct hash_elem *a_, const struct hash_elem *b_,
@@ -85,11 +86,8 @@ mmap_unmap (struct mmap_entry *mmap)
     hash_delete (&thread_current ()->pages, &page->elem);
   }
 
-  /* Remove the mapping from the mmap table. Close the file and free the mmap
-     entry. */
-  hash_delete (&thread_current ()->mmap_files, &mmap->elem);
   file_close (mmap->file);
-  free(mmap);
+  free (mmap);
 }
 
 /* Destroys the mmap table for the current thread. Frees all the memory
@@ -120,14 +118,13 @@ mmap_less (const struct hash_elem *a_, const struct hash_elem *b_,
   return a->mapping < b->mapping;
 }
 
-/* Cleans up the mmap table for the current thread. Frees the memory allocated
-   for the mmap entry. */
+/* Cleans up the mmap table for the current thread. Implicitly unmaps the mmap
+   entry, freeing pages and writing back to the file if necessary. */
 static void
 mmap_cleanup (struct hash_elem *e, void *aux UNUSED)
 {
   struct mmap_entry *mmap = hash_entry (e, struct mmap_entry, elem);
-  file_close (mmap->file);
-  free (mmap);
+  mmap_unmap (mmap);
 }
 
 /* Updates the 'owner' thread's page table entry for virtual address 'upage'

src/vm/mmap.h

@@ -21,6 +21,7 @@ bool mmap_init (struct thread *t);
 struct mmap_entry *mmap_get (mapid_t mapping);
 struct mmap_entry *mmap_insert (struct file *file, void *upage);
 void mmap_unmap (struct mmap_entry *mmap);
+void mmap_umap_all (void);
 void mmap_destroy (void);
 
 #endif /* vm/mmap.h */

src/vm/page.c

@@ -59,7 +59,6 @@ page_get (void *upage)
 
   struct hash_elem *e
     = hash_find (&thread_current ()->pages, &fake_page_entry.elem);
-
   if (e == NULL)
       return NULL;