Re: LANANA: To Pending Device Number Registrants

Alexander Viro
2001-05-15T20:41:48Z

On Tue, 15 May 2001, H. Peter Anvin wrote:

> Permission management. The permissions on the subnodes are inherited
> from the main node, which is stored on a persistent medium.

If you want them all to inherit it - inherit from mountpoint. End of story.
Yes, it means that permission(9) will need vfsmount argument. But we
_will_ need that anyway. For per-mountpoint read-only, if nothing else.

Want details? Please. We have the ->getattr() method. Currently not
used, but intended to be used by ...stat family (with the current
behaviour being default). Now, let's pass to permission(9), notify_change(9)
and ->{set,get}attr() both vfsmount and dentry. See what I mean?

We get (essentially for free)
* per-mountpoint read-only flag (I've already done nosuid, noexec
and nodev per-mountpoint)
* ability to have inodes that simply don't have owners - ownership
is determined (and handled) by the functions/methods above. So FAT and
friends can get rid of knowledge of uid=,gid=" crap.
* ability to inherit ownership from mountpoint and if fs wants it -
update the ownership of mountpoint.