Re: [patch] stop inotify from sending random DELETE_SELF event under load

[Al Viro <viro@ftp.linux.org.uk>]

On Tue, Sep 20, 2005 at 01:06:23AM -0400, John McCutchan wrote:
> On Tue, 2005-09-20 at 05:58 +0100, Al Viro wrote:
> > On Tue, Sep 20, 2005 at 12:53:12AM -0400, John McCutchan wrote:
> > > DELETE_SELF WD=X
> > > 
> > > The path you requested a watch on (inotify_add_watch(path,mask) returned
> > > X) has been deleted.
> > 
> > Then why the devil do we have IN_DELETE and IN_DELETE_SELF generated
> > in different places?  The only difference is in who receives the
> > event - you send IN_DELETE to watchers on parent and IN_DELETE_SELF
> > on watchers on victim.  Event itself is the same, judging by your
> > description...
> 
> No, because in the case of IN_DELETE, the path represented by the WD
> hasn't been deleted, it is "PATH(WD)/event->name" that has been.

That's OK - same thing described for different recepients, thus two
events with different contents and type being sent.

> Also,
> IN_DELETE_SELF marks the death of the WD, no further events will be sent
> with the same WD [Except for the IN_IGNORE]. 

Uh-oh...  Now, _that_ is rather interesting - you are giving self-contradictory
descriptions of the semantics.

fd = open("foo", 0);
unlink("foo");
sleep for a day
fchmod(fd, 0400);
sleep for a day
close(fd);

Which events do we have here?  Removal of path happens at unlink(); change
of attributes - a day later.