 File-system consistency checker

A program that compares independently represented facts in a file system, such as the hard link counts in inodes versus references found in directory entries, or the block allocation bitmap versus block ownership recovered from inodes and reserved structures. Disagreement detects corruption; repair policies must decide which evidence to trust and preserve recoverable data. A scan of names alone is insufficient to infer live ownership while the file system is changing or has unnamed open files, so checking requires a suitable stable view.