* Christian Schoenebeck (qemu_oss@xxxxxxxxxxxxx) wrote: > On Dienstag, 4. August 2020 13:28:01 CEST Dr. David Alan Gilbert wrote: > > > Well, depends on how large you draw the scope here. For instance Samba has > > > a bunch VFS modules which also uses and hence prohibits certain xattrs. > > > For instance for supporting (NTFS) alternate data streams (a.k.a. > > > resource forks) of Windows clients it uses user.DosStream.*: > > > > > > https://www.samba.org/samba/docs/current/man-html/vfs_streams_xattr.8.html > > > > > > as well as "user.DOSATTRIB". > > > > > > And as macOS heavily relies on resource forks (i.e. macOS doesn't work > > > without them), there are a bunch of xattr remappings in the dedicated > > > Apple VFS module, like "aapl_*": > > > > > > https://www.samba.org/samba/docs/current/man-html/vfs_fruit.8.html > > > https://github.com/samba-team/samba/blob/master/source3/modules/vfs_fruit. > > > c > > > > Thanks; what I've added to virtiofsd at the moment is a generic > > remapping thing that lets me add any prefix and block/drop any xattr. > > Right, makes absolutely sense to make it configurable. There are too many use > cases for xattrs, and the precise xattr names are often configurable as well, > like with the mentioned Samba VFS modules. > > > The other samba-ism I found was mvxattr(1) which lets you rename xattr's > > ona directory tree; which is quite useful. > > Haven't seen that before, interesting. > > BTW, I have plans for adding support for file forks [1] (a.k.a. alternate > streams, a.k.a. resource forks) on Linux kernel side, so I will probably come > up with an RFC in couple weeks to see whether there would be acceptance for > that at all and if yes in which form. > > That would open a similar problematic to virtiofsd on the long term, as file > forks have a namespace on their own. Yeh I'm sure that'll need wiring into lots of things in weird ways! I guess the main difference between an extended attribute and a file-fork is that you can access the fork using an fd and it feels more like a file? Dave > [1] https://en.wikipedia.org/wiki/Fork_(file_system) > > Best regards, > Christian Schoenebeck > > -- Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
