Re: [RFC][PATCH] Add a dentry op to handle automounting rather than abusing follow_link

[Nick Piggin <npiggin@suse.de>]

This hasn't had much comments yet.

On Tue, Jul 13, 2010 at 10:55:50PM +0100, David Howells wrote:
> 
> Add a dentry op (d_automount) to handle automounting directories rather than
> abusing the follow_link() inode operation.
> 
> I've only changed __follow_mount() to handle automount points, but it might be
> necessary to change follow_mount() too.  The latter is only used from
> follow_dotdot(), but any automounts on ".." should be pinned whilst we're using
> a child of it.
> 
> AFS is made to use this facility so that it can be tested.  Other filesystems
> abusing the follow_mount() inode operation will also need to be modified.

How about having a .follow_mount op, and using that instead of
default follow_mount in case mounted is incremented?

Also I would prefer the patch to add this call keep basically the
same API as follow_mount, so if you are going to change that to
return an error and do the NOFOLLOW handling in there, then
could you do that first, as a more trivial patch?

Then your addition of the d_op should not touch outside
*follow_mount.