add locking around file syscalls inside page table

1 files changed, 5 insertions, 0 deletions

diff --git a/vm/page.c b/vm/page.c
index b98c553..c10113a 100644
--- a/vm/page.c
+++ b/vm/page.c
@@ -121,7 +121,9 @@ page_load (struct page_table_entry *pte)
     return true;
 
   data = &pte->segment;
+  process_lock_filesys ();
   file_seek (data->file, data->ofs);
+  process_unlock_filesys ();
 
   /* Get a page of memory. */
   uint8_t *kpage = palloc_get_page (PAL_USER);
@@ -129,12 +131,15 @@ page_load (struct page_table_entry *pte)
     return false;
 
   /* Load this page. */
+  process_lock_filesys ();
   if (file_read (data->file, kpage, data->read_bytes)
       != (int) data->read_bytes)
     {
       palloc_free_page (kpage);
+      process_unlock_filesys ();
       return false;
     }
+  process_unlock_filesys ();
   memset (kpage + data->read_bytes, 0, PGSIZE - data->read_bytes);
 
   /* Add the page to the process's address space. */