System Administration Guide: Devices and File Systems

Link Count Checks

Each inode contains a count of the number of directory entries linked to it. The fsck command verifies the link count of each inode by examining the entire directory structure, starting from the root (/) directory, and calculating an actual link count for each inode.

Discrepancies between the link count stored in the inode and the actual link count as determined by the fsck command might be one of three types: