Bugzilla Bug 43027

The FAM library can take advantage of Linux's dnotify feature to avoid polling
files for changes. It's not part of standard fam distribution, you have to
apply a patch. This patch was removed from app-admin/fam in 2.7.0 (2.6.10-r1
had it). There's no mention of it in ChangeLog other than "New release,
obsoletes most of the patches", so maybe it was a mistake? Anyway, this patch
is pretty important (it improves responsibility), so I took updated patch for
2.7.0 from Debian package and modified the ebuild to apply it. Patches
attached, tested & working.

Reproducible: Always
Steps to Reproduce:

Created an attachment (id=26426) [details]
patch for  the ebuild

Created an attachment (id=26427) [details]
fam-2.7.0-dnotify.patch

Yes, thats correct. However, with DNotify there is another issue in descriptor
leakage for removable devices.  By not providing the DNotify event tracker in
fam there is no longer an issue with this, which is of more importance than the
slight boost in responsiveness.

Are you sure this is still true for 2.7.0 and latest (i.e. this one, Debian's)
version of dnotify patch? From Debian's changelog
(http://packages.debian.org/changelogs/pool/main/f/fam/fam_2.7.0-5/changelog):
"""
fam (2.7.0-1) experimental; urgency=low

  * New upstream release 
    (closes: Bug#224738):
    - should fix problems with unmounting filesystems with
      monitored files 
      (closes: Bug#225636)
"""
Comment #27 at http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=106936 seems
to indicate DNotify patch was fixed, too (it's dated 2004-02-04).

> which is of more importance than the slight boost in responsiveness.

As for "slight", I noticed this because KGhostview's Watch File feature started
to react considerably slower (as in immediately vs. something that felt like
1-2 seconds later) after I set up famd.

ok re-added dnotify support in fam-2.7.0-r1

I indeed couldn't reproduce the old locking problems, but that might also have todo with fixes in other packages. We'll just have to see how it goes. This patch seems quite a bit altered from the original.

about 'slight' , fam without monitor polls once p.sec afaik vs almost immediatly now. It looks better, but it doesn't matter that much.

Here, with fam-2.7.0-r1, I've still the problem with removable devices...

describe the exact problem & how it is reproducable . I can't reproduce the old
problem.

Well, it's quite simple :

In nautilus :
- start famd...
- mount a floppy/usbkey
- access it with nautilus to copy or read some files on it
- try to unmount the floppy/usbkey

Nautilus complains the device is busy... Try in a term. Same thing. With a lsof, you see that the mount point is beeing monitored by famd... Restart or stop famd : you can unmount.