For the "which disk blocks" exercise, the answer is A.


Superblocks and cylinder groups have accurate counts.
•  Every directory entry references a valid inode.
•  Every valid inode appears in a number of directory entries equal to its link count.
•  Blocks allocated to valid inodes are marked inuse in bitmaps.
•  A block belongs to only one file/directory.
•  The first two entries in every directory are . and ..
•  What makes an inode valid?
* * Its length and number of blocks are consistent with the blocks allocated to it.
* * All block pointers are valid in the given file system.
* * If an inode references a directory, its size is a multiple of DIRBLKSIZ.
* * Its inode number is correct.

Log records during file creation:

* Create file A, write blocks 0-2 into the file.
* Write directory entry? NO!!! First initialize inode.

L1: Allocate and initialize inode 10
L2: Add directory entry: A, 10

Now we need to allocate some blocks to the file.
Suppose we are allocating it physical blocks 1234, 1235, 1236

L3: Alloc block 1234 to inode 10 (lbn 0)
L4: Alloc block 1235 to inode 10 (lbn 1)
L5: Alloc block 1236 to inode 10 (lbn 2)

Log records during file deletion:
Delete file A (and all of its blocks

L1: Remove directory entry A, 10
L2: Free block 1234
L3: Free block 1235
L4: Free block 1236
L5: Clear inode 10
L6: Deallocate inode 10



????
bitmap: inode 11 is allocated
inode 11 gets the following content
directory entry foo points to inode 11.