On Mon, Aug 17, 2020 at 08:56:20AM +1000, Dave Chinner wrote: > Indeed, most filesystems will not be able to implement ADS as > xattrs. xattrs are implemented as atomicly journalled metadata on > most filesytems, they cannot be used like a seekable file by > userspace at all. If you want ADS to masquerade as an xattr, then > you have to graft the entire file IO path onto filesytsem xattrs, > and that just ain't gonna work without a -lot- of development in > every filesystem that wants to support ADS. > > We've already got a perfectly good presentation layer for user data > files that are accessed by file descriptors (i.e. directories > containing files), so that should be the presentation layer you seek > to extend. > > IOWs, trying to use abuse xattrs for ADS support is a non-starter. One thing Dave didn't mention is that a directory can have xattrs, forks and files (and acls). So your presentation layer needs to not confuse one thing for another. I don't understand why a fork would be permitted to have its own permissions. That makes no sense. Silly Solaris.
