[$] The Btrfs inode-number epic (part 1: the problem)

Unix-like systems - and their users - tend to expect all filesystems tobehave in the same way. But those users are also often interested in fancynew filesystems offering features that were never envisioned by thedevelopers of the Unix filesystem model; that has led to a number ofinteresting incompatibilities over time. Btrfs is certainly one of thosefilesystems; it provides a long list of features that are found in fewother systems, and some of those features interact poorly with thetraditional view of how filesystems work. Recently, Neil Brown has beentrying to resolve a specific source of confusion relating to how Btrfshandles inode numbers.