file change notification issues

[Juergen Hasch]

Jeremy,

jra at dp.samba.org wrote:

>Great detective work ! Actaully this is a bug in IIS. The
>protocol states that STATUS_NOTIFY_ENUM_DIR is a valid return,
>if too many files were changed (hmmm. define "too many" :-).
>
>It would be possible to cause this to break on Windows 2000
>servers also, but I imagine that under 'normal' circumstances
>few enough files have changed that this doesn't cause a problem
>for IIS.
>
well it looks like Matlab, the application I'm having trouble with, also 
doesn't like STATUS_NOTIFY_ENUM_DIR
as return value. It starts polling its working directory like crazy, 
which is quite annyoing (you can change the program
configuration, but this is the default for me). Older versions of Matlab 
behave better, I checked this some time ago.

I hacked a patch to have Samba behave like W2K and deliver the name of 
the changed file and it looks quite good.
No more endless file stat polling, so I'm all for adding this 
functionality to Samba :-)

The most difficult part is getting a file name from Linux  without 
reimplementing the change  notification interface.
 I don't like fam or dazuko or the other stuff that is available as an 
alternative to the kernel  dnotify support,
it's too much bloat.
For now I simply added a fcntl to the Linux kernel to return the desired 
file name. This requires only minor changes
in Samba and Linux, however it has most likely races in it and will 
probably only work for my  most simple case...

...Juergen

Btw. my original problem from my posts last week was different. It seems 
like the behaviour I was describing only
happens when running Samba in a VMware session. Testing on several real 
machines doesn't show the problem.
Odd... I can still send you traces, but I think it's not that interesting.