Subject: Re: union mount directory permissions
To: Eric Haszlakiewicz <>
From: David Laight <>
List: tech-kern
Date: 09/28/2004 08:09:27
>      * policy: when creating the shadow directory in the
>      * upper layer, create it owned by the user who did
>      * the mount, group from parent directory, and mode
>      * 777 modified by umask (ie mostly identical to the
>      * mkdir syscall).  (jsp, kb)
> uhm.. so, why?  File permissions and ownership are copied.  Shouldn't
> directories behave the same?

When I wrote a union fs, I created directories with the permissions
of their real parent.

I also deceided that the 'copy file into top layer' action was
unnecessary.  Nothing we ran needed it.

I did try to use the feature of SVR4 VOP_OPEN() that allows it to return
a different vnode (use for clone open on special devices) but not all
of the kernel liked me doing that.


David Laight: