Chapter 40, file-implementation.pdf

Figure 40.4: the first read of the bar inode is not needed; since the file is being created,
the original inode contents are irrelevant.

homework/file-implementation/README.md

Example reference count for root directory should be 3, not 6:

*** ORIG/README.md      2021-03-01 13:09:07.000000000 -0500
--- README.md   2021-06-04 16:19:49.618657707 -0400
***************
*** 77,83 ****

  ```sh
  inode bitmap 11110000
! inodes       [d a:0 r:6] [f a:1 r:1] [f a:-1 r:1] [d a:2 r:2] [] ...
  data bitmap  11100000
  data         [(.,0) (..,0) (y,1) (z,2) (f,3)] [u] [(.,3) (..,0)] [] ...
  ```
--- 77,83 ----

  ```sh
  inode bitmap 11110000
! inodes       [d a:0 r:3] [f a:1 r:1] [f a:-1 r:1] [d a:2 r:2] [] ...
  data bitmap  11100000
  data         [(.,0) (..,0) (y,1) (z,2) (f,3)] [u] [(.,3) (..,0)] [] ...
  ```

homework/file-implementation/vsfs.py

When writing data, should show the data value, otherwise can't answer the question:

% python ./vsfs.py.ORIG -r -s 1
...
fd=open("/n/x", O_WRONLY|O_APPEND); write(fd, buf, BLOCKSIZE); close(fd);

  State of file system (inode bitmap, inodes, data bitmap, data)?
...

% python ./vsfs.py -r -s 1
...
fd=open("/n/x", O_WRONLY|O_APPEND); write(fd, "o", BLOCKSIZE); close(fd);

  State of file system (inode bitmap, inodes, data bitmap, data)?
...

Answer for data in above example needs to know that "o" was written:

data          [(.,0) (..,0) (n,1)] [(.,1) (..,0) (x,2)] [o] [] [] [] [] []
---------------------------------------------------------^

fix:

% diff vsfs.py.ORIG vsfs.py
392c392
<             print('fd=open("%s", O_WRONLY|O_APPEND); write(fd, buf, BLOCKSIZE); close(fd);' % tfile)
---
>             print('fd=open("%s", O_WRONLY|O_APPEND); write(fd, "%c", BLOCKSIZE); close(fd);' % (tfile,data))
e
%