Switch the base file system from direct-indexed inodes to extents.

[pintos-anon] / src / filesys / filesys.c

diff --git a/src/filesys/filesys.c b/src/filesys/filesys.c
index 440fc57eeada117c19007e480f69f25848ddad61..6a763fecdb60e8e8b323e0d706c20b7ea6549e43 100644 (file)
--- 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.