6.2. An overview of filing system functions
Filing systems provide:
a storage service: clients do not need to know about the physical characteristics of disks, or where files have been stored on them. The filing system should take steps not to lose a file that has been entrusted to it, even if there are hardware faults or software crashes;
a directory service: clients can give convenient text names to files and, by grouping them in directories, show the relationships between them. Clients should also be able to control the sharing of their files with others by specifying who can access a given file and in what way.
Figure 6.1 illustrates a typical interaction between a file service and a client. We shall see later that filing system designs differ, ...