lock open_inodes

1 files changed, 11 insertions, 1 deletions

diff --git a/src/filesys/inode.c b/src/filesys/inode.c
index cfdcb7b..78c1972 100644
--- a/src/filesys/inode.c
+++ b/src/filesys/inode.c
@@ -6,6 +6,7 @@
 #include "filesys/filesys.h"
 #include "filesys/free-map.h"
 #include "threads/malloc.h"
+#include "threads/synch.h"
 
 /* Identifies an inode. */
 #define INODE_MAGIC 0x494e4f44
@@ -53,6 +54,9 @@ byte_to_sector (const struct inode *inode, off_t pos)
     return -1;
 }
 
+/* Lock the open inode list since so inode_open doesn't race. */
+struct lock open_inodes_lock;
+
 /* List of open inodes, so that opening a single inode twice
    returns the same `struct inode'. */
 static struct list open_inodes;
@@ -62,6 +66,7 @@ void
 inode_init (void) 
 {
   list_init (&open_inodes);
+  lock_init (&open_inodes_lock);
 }
 
 /* Initializes an inode with LENGTH bytes of data and
@@ -114,6 +119,7 @@ inode_open (disk_sector_t sector)
   struct list_elem *e;
   struct inode *inode;
 
+  lock_acquire (&open_inodes_lock);
   /* Check whether this inode is already open. */
   for (e = list_begin (&open_inodes); e != list_end (&open_inodes);
        e = list_next (e)) 
@@ -122,14 +128,17 @@ inode_open (disk_sector_t sector)
       if (inode->sector == sector) 
         {
           inode_reopen (inode);
+          lock_release (&open_inodes_lock);
           return inode; 
         }
     }
 
   /* Allocate memory. */
   inode = malloc (sizeof *inode);
-  if (inode == NULL)
+  if (inode == NULL) {
+    lock_release (&open_inodes_lock);
     return NULL;
+  }
 
   /* Initialize. */
   list_push_front (&open_inodes, &inode->elem);
@@ -137,6 +146,7 @@ inode_open (disk_sector_t sector)
   inode->open_cnt = 1;
   inode->deny_write_cnt = 0;
   inode->removed = false;
+  lock_release (&open_inodes_lock);
   disk_read (filesys_disk, inode->sector, &inode->data);
   return inode;
 }