Re: [RFC] shared subtrees

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Feb 01, 2005 at 06:37:54PM -0500, J. Bruce Fields wrote:
> I think the question you meant to ask was what would happen if you
> mounted something on /tmp/mnt2/a/b (the slave copy) and then mounted
> something else on /tmp/mnt1/a/b.  In that case there's two places where
> the propagated mount might go:
> 	1. On top of the dentry a/b in /tmp/mnt2, underneath the
> 	   preexisting mount.
> 	2. On top of the root dentry of the thing mounted in
> 	   /tmp/mnt2/a/b, thus covering the preexisting mount.
> 
> Wouldn't option 1 require changing the mnt_parent of the preexisting
> mount on /tmp/mnt2/a/b?  That seems like an odd thing to do, so I assume
> option 2 is the only possible solution, but perhaps I'm missing
> something.

Yes, I'm confused: --move, for example, changes the mnt_parent, and it's
only ever used under vfsmount_lock.

So #1, which adheres to the rule that all the clones are mounted at the
same dentry, probably makes more sense.--b.