Indication of extended attributes availability.

[Robert Watson]

On Sun, 23 Mar 2008, Václav Haisman wrote:

> What about <http://shell.sh.cvut.cz/~wilx/freebsd/extattr2.diff>? It extends 
> ufs_pathconf() with handling of _PC_XATTR_ENABLED. The patch is untested.

I think it sounds fairly reasonable.  However, the switch for ufs_pathconf() 
appears to be missing the _PC_XATTR_EXISTS case?

I'd probably panic rather than KASSERT() there.

I'll also need to update the fpathconf(2) man page to list _PC_XATTR_*.

Finally, I'm not convinced, having reread the fsattr man page on Solaris, that 
what they mean by XATTR is what we mean by extended attribute.  However, I 
think that's a confusion fairly specific to Solaris and that we do have and 
apply a consistent meaning for extended attribute.  A question for Pawel would 
be how he plans to expose ZFS "extended attributes" (file streams) in FreeBSD, 
so I've CC'd him.

Robert N M Watson
Computer Laboratory
University of Cambridge