The fanotify API - corrections

The global method should work fine then surely; set a global listener, and ignore any notifications where the pathname doesn't begin with your required string (eg, '/home/'). If you're worried that that'll get triggered more often that it need be (esp if you want different trees monitored for different purposes) then it's not much work to create a plugable super-server that listens globally and hands you the notifications you're interested in... then everyone can have their own monitoring process for their own home directory, without there being several processes woken with each file opened... and the super-server could do extra things like make sure the monitor has read access to the file opened before handing it the FD.

Also, the fact that inotify and dnotify code can be dropped from the kernel and replaced by slim wrappers around these calls instead makes sense from a code tidying/maintenance point of view. If you really think that inotify is the interface you want to use, but want it to be able to watch entire sections of the filesystem (a 'recurse' flag), then as inotify will become a wrapper around this interface that will allow you to do it, it's really not going to be hard for you to add that feature to it.