Homework chapter 13
1.
Consider a file system in which a file can be deleted and its disk space reclaimed while links to that file still exist. What problems may occur if a new file is created in the same storage area or with the same absolute path name? How can these problems be avoided?
The problem that would occur is that users might think that they are accessing the old file while in reality they are accessing the new one because the links to the old file are now pointing to the
new file; Also, t
he access protection for old file is used for the new file.
To avoid this problem, we need to remove all links to a file when it is deleted by maintaining a list of all links to a file, removing each of them when the file is deleted. 2.
What are the advantages and disadvantages of providing mandatory locks instead of advisory locks whose use is left to users' discretion?
Advantages:
It guarantees memory locks to provide synchronization
Limits the flexibility for files being accessed
May result to mutual exclusion as different programs work concurrently and trying to access the same file
Disadvantage
The overhead associated with files will increase
3.
If the operating system knew that a certain application was going to access file data in a sequential manner, how could it exploit this information to improve performance?
In order to improve performance, the filesystem could prefetch the consequent blocks in suspicion of future requests to these blocks at the point when block is accessed; this could reduce the waiting time by the process for future requests.
