Re: [RFC/PATCH] Nonotify - A simplistic way to determine directory content changes

[John McCutchan <ttb tentacle dhs org>]

On Sat, 2004-06-05 at 05:15, nf2 scheinwelt at wrote:
> Quoting Alexander Larsson <alexl redhat com>:
> 
> > On Fri, 2004-06-04 at 19:21, Manuel Amador (Rudd-O) wrote:
> > > El vie, 04-06-2004 a las 03:23, Alexander Larsson escribió:
> > 
> > > > Yeah, being provocative rarely helps your cause, it just tends to make
> > > > people ignore you. Anyway, thanks for working on this (long standing)
> > > > problem and actually thinking out of the box.
> > > 
> > > 
> > > Only one question remains.  Does nonotify require open fds?  I mean,
> > > will it block cdrom ejection? =)
> > 
> > Eh, it obviously does, which was clear in the original proposal (the
> > talk about pinning down dentries).
> > 
> 
> Just to put this right: Nonotify does NOT require open fd's, it does NOT pin
> down dentries and it does NOT block cdrom ejection.
> 
> Nonotify just uses a modified stat-call to read the new 'dcontents_mtime' field.
> Nothing else. Stat-calls don't open fd's and don't block.

Yes it does. When you call stat() there is a bunch of activity on the
filesystem that will stop cdrom ejection during the stat call. Assuming
that nonotify is stat()ing every X ms, there is a race between the
stat() call and the unmount. So it could happen, but it would be rare.

John