[NCLUG] meeting 6pm November 6th, NEW LOCATION

[Matt Taggart]

NCLUG meeting
Date: Tuesday November 6th, 6pm
NEW Location: Home State Bank, 303 E. Mountain Ave
  Go in the front door and take the elevator to the basement
Bring money for pizza and soda
We will be having a speaker. No, I'm not joking.

Speaker: Matthew Wilcox
Subject: Leases & Directory Notification
Abstract:

This paper describes how the Linux kernel was extended to supply Leases &
Directory notifications to applications.  Leases allow an application
to be notified when a file is modified, allowing that application the
opportunity to cache changes until such time as they must become visible
to others.  Directory notification allows an application to be notified
when the contents of a directory change.

Both of these features were added to enhance the performance and
correctness of the Samba SMB file server, but have applications
beyond this.  In the specific case of Samba, leases allow clients the
optimisation of lazily committing data to the server which is a major
performance gain in most cases.  Directory notification allows Samba to
support correctly the SMB operation of the same name instead of faking
it by polling the directory every 30 seconds.

Other applications for these enhancements can be envisaged.  One obvious
application is a file manager which uses directory notification to ensure
that its display is constantly up to date.  Unfortunately, Nautilus has
opted to use imon/fam and this paper discusses why this is a bad model.
A make `daemon' could also be developed which watches for changes to
directories (eg new versions of files being written) and automatically
rebuilds the project.

A further enhancement which was made to the kernel was the addition of
DOS/Windows `Share Modes'.  These permit one application to deny any
further applications the right to open a file.  As part of these changes,
the current POSIX file locking code was improved.  Finally, the holy grail
of multi-protocol file serving was realised --- NFS locks and SMB locks
were made to interact correctly.


willy assures me that this talk is aimed at a general audience, so don't be 
intimidated by the subject matter.

See you there!

-- 
Matt Taggart
matt at lackof.org