Re: Finding hardlinks

[Shaya Potter <spotter@cs.columbia.edu>]

On Thu, 2006-12-28 at 09:58 -0800, Bryan Henderson wrote:
> >Adding a vfs call to check for file equivalence seems like a good idea to 
> me.
> 
> That would be only barely useful.  It would let 'diff' say, "those are 
> both the same file," but wouldn't be useful for something trying to 
> duplicate a filesystem (e.g. a backup program).  Such a program can't do 
> the comparison between every possible pairing of file names.
> 
> I'd rather just see a unique file identifier that's as big as it needs to 
> be.  And the more unique the better.  (There are lots of degrees of 
> uniqueness; unique as long as the files exist; as long as the filesystems 
> are mounted, etc.).

the other option which wouldn't work with file system as they exist
today would be for a system call that would say "give inode X, give me
all name links to this inode".  Essentially a reverse database of sorts

As I said, wouldn't work with today's file systems, but would help
stackable file systems, as they have no way of knowing about hard links,
at least if not created through them (and in that case they would have
to implement the above mentioned reverse database).