lock create/remove

1 files changed, 11 insertions, 5 deletions

diff --git a/src/filesys/filesys.c b/src/filesys/filesys.c
index fedda08..789bcf2 100644
--- a/src/filesys/filesys.c
+++ b/src/filesys/filesys.c
@@ -8,6 +8,8 @@
 #include "filesys/directory.h"
 #include "devices/disk.h"
 
+static struct lock create_lock;
+
 /* The disk that contains the file system. */
 struct disk *filesys_disk;
 
@@ -22,6 +24,8 @@ filesys_init (bool format)
   if (filesys_disk == NULL)
     PANIC ("hd0:1 (hdb) not present, file system initialization failed");
 
+  lock_init (&create_lock);
+
   inode_init ();
   free_map_init ();
 
@@ -48,12 +52,14 @@ filesys_create (const char *name, off_t initial_size)
 {
   disk_sector_t inode_sector = 0;
   struct dir *dir = dir_open_root ();
+  lock_acquire (&create_lock);
   bool success = (dir != NULL
-                  && free_map_allocate (1, &inode_sector)
-                  && inode_create (inode_sector, initial_size)
-                  && dir_add (dir, name, inode_sector));
-  if (!success && inode_sector != 0) 
-    free_map_release (inode_sector, 1);
+                  && free_map_allocate (1, &inode_sector)       // find sector
+                  && inode_create (inode_sector, initial_size)  // create inode pointing to sector
+                  && dir_add (dir, name, inode_sector));        // add dir entry pointing to inode
+  lock_release (&create_lock);
+  if (!success && inode_sector != 0)     // oops, we got a sector but file creation failed
+    free_map_release (inode_sector, 1);  // so deallocate the sector
   dir_close (dir);
 
   return success;