On Sun, 11 May 2025 at 11:56, Chen Linxuan <chenlinxuan@xxxxxxxxxxxxx> wrote: > I noticed that the current extended attribute names already use the > namespace.value format. > Perhaps we could reuse this naming scheme and extend it to support > features like nested namespaces. Right. Here's a link to an old and long thread about this: https://lore.kernel.org/all/YnEeuw6fd1A8usjj@xxxxxxxxxxxxxxxxxxxxxxxxx/#r > > For instance, in a situation like this: > > A fixed file 0 in an io_uring is a FUSE fd. > This FUSE fd belongs to FUSE connection 64. > This FUSE fd has a backing file. > This backing file is actually provided by mnt_id=36. > > Running getfattr -m '-' /proc/path/to/the/io_uring/fd could return > something like: > > io_uring.fixed_files.0.fuse.conn="64" > io_uring.fixed_files.0.fuse.backing_file.mnt_id="36" > io_uring.fixed_files.0.fuse.backing_file.path="/path/to/real/file" Yeah, except listxattr wouldn't be able to properly work in such cases: it lacks support for hierarchy. The proposed solution was something like making getxattr on the "directory" return a listing of child object names. I.e. getxattr("/proc/123/fd/12", "io_uring.fixed_files.") would return the list of instantiated fixed file slots, etc... Thanks, Miklos
