Directory hierarchy traversal and the dentry cache

• When we attempt to open a file, the system needs to check all the path components, one by one:
  • to verify their existence
  • to check our access permissions
  • to follow symbolic links
• This requires bringing data from the disk (the directories data), in a random-access manner --> SLOW.
• To speed up - fetched directory data is stored in the kernel's "dentry cache".

Originally written by guy keren