Re: Detecting changes in a directory tree

[Jeroen van Disseldorp <jdizzl@xs4all.nl>]

On Thursday 16 January 2003 19:59, Adrian Bunk wrote:
> with a kernel >= 2.4.19 dnotify [1] might do what you want.

Close, but is doesn't do it quite for me. I understand the problem of 
traversing inodes back up the tree, once they have changed, to see 
whether someone wants to receive an event. However I am not convinced 
that this is necessary. The idea I had was the following:

I would like to have a passthrough kind of filesystem (lets call is myfs 
for now) that can mount other parts of the filesystem and just maps 
everything to the original tree. For instance, I would mount /var on 
/mnt/var, using myfs. Everything from /mnt/var is directly mapped to 
/var.

The clue of this is that myfs *knows* about the notification, because it 
has to send notification to userspace for *every* inode. So if anything 
is written in /mnt/var, it can notify userspace. BTW for my app it 
would be acceptable that direct changes in /var don't lead to any 
events.

I haven't thought out the interface to userspace yet, but I think that 
can be worked out. Let me know if I'm making any sense here.

Regards,
  Jeroen                           mailto:jdizzl@xs4all.nl
-- 
Be the change that you want to see in the world    -- Gandhi