file metadata via fs API

[David Howells]

Miklos Szeredi <miklos at szeredi.hu> wrote:

> That presumably means the mount ID <-> mount path mapping already
> exists, which means it's just possible to use the open(mount_path,
> O_PATH) to obtain the base fd.

No, you can't.  A path more correspond to multiple mounts stacked on top of
each other, e.g.:

	mount -t tmpfs none /mnt
	mount -t tmpfs none /mnt
	mount -t tmpfs none /mnt

Now you have three co-located mounts and you can't use the path to
differentiate them.  I think this might be an issue in autofs, but Ian would
need to comment on that.

David