X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Ffilesys%2Ffilesys.c;h=6a763fecdb60e8e8b323e0d706c20b7ea6549e43;hb=3ed7340d796b1a5cafe45ec78b80415f09eb3fa9;hp=28a2f7f046eb748c5946d1b8579699ee9c52b7e6;hpb=2e6303a4b957eb770b0cab4172bd43a7c01c927d;p=pintos-anon

diff --git a/src/filesys/filesys.c b/src/filesys/filesys.c
index 28a2f7f..6a763fe 100644
--- a/src/filesys/filesys.c
+++ b/src/filesys/filesys.c
@@ -38,10 +38,11 @@
 
 /* Filesystem.
 
-   For the purposes of the "user processes" assignment (project
-   2), please treat all the code in the filesys directory as a
-   black box.  No changes should be needed.  For that project, a
-   single lock external to the filesystem code suffices.
+   For the purposes of the "user processes" and "virtual memory"
+   assignments (projects 2 and 3), please treat all the code in
+   the filesys directory as a black box.  No changes should be
+   needed.  For those projects, a single lock external to the
+   filesystem code suffices.
 
    The filesystem consists of a set of files.  Each file has a
    header called an `index node' or `inode', represented by
@@ -73,10 +74,9 @@
        directory is represented as a file, the number of files
        that may be created is also limited.
 
-     - No indirect blocks.  This limits maximum file size to the
-       number of sector pointers that fit in a single inode
-       times the size of a sector, or 126 * 512 == 63 kB given
-       32-bit sizes and 512-byte sectors.
+     - File data is allocated as a single extent, so that
+       external fragmentation can become a serious problem as a
+       file system is used over time.
 
      - No subdirectories.
 
@@ -166,8 +166,7 @@ filesys_create (const char *name, off_t initial_size)
   if (free_map == NULL)
     goto done;
   bitmap_read (free_map, free_map_file);
-  inode_sector = bitmap_scan_and_flip (free_map, 0, disk_size (filesys_disk),
-                                       false);
+  inode_sector = bitmap_scan_and_flip (free_map, 0, 1, false);
   if (inode_sector == BITMAP_ERROR)
     goto done;
 
@@ -198,7 +197,8 @@ filesys_create (const char *name, off_t initial_size)
 
 /* Opens a file named NAME and initializes FILE for usage with
    the file_*() functions declared in file.h.
-   Returns true if successful, false on failure.
+   Returns the new file if successful or a null pointer
+   otherwise.
    Fails if no file named NAME exists,
    or if an internal memory allocation fails. */
 struct file *
@@ -242,7 +242,7 @@ filesys_remove (const char *name)
   if (!dir_lookup (dir, name, &inode_sector))
     goto done;
 
-  /* Open the inode and delete it it. */
+  /* Open the inode and delete it. */
   inode = inode_open (inode_sector);
   if (inode == NULL)
     goto done;