[Linux-cluster] [RFC] NLM lock failover admin interface

[Stanley, Jon]

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Wendy Cheng
> Sent: Monday, June 12, 2006 12:26 AM
> To: nfs at lists.sourceforge.net
> Cc: linux-cluster at redhat.com
> Subject: [Linux-cluster] [RFC] NLM lock failover admin interface
> 
NOTE - I don't use NFS functionality in Cluster Suite, so my coments may
be entirely meaningless.

> 
> 1. /proc interface, say writing the fsid into a /proc directory entry
> would end up dropping all NLM locks associated with the NFS 
> export that
> has fsid in its /etc/exports file.

This would defintely have it's advantages for people who know what
they're doing - they could drop all locks without unexporting the
filesystem.  However, it also gives people the opportunity to shoot
themselves in the foot - by eliminating locks that are needed.  After
weighing the pros and cons, I really don't think that any method
accessible via /proc is a good idea.

> 
> 2. Adding a new flag into "exportfs" command, say "h", such that
> 
>    "exportfs -uh *:/export_path"
> 
> would un-export the entry and drop the NLM locks associated with the
> entry.
> 

This is the best of the three, IMHO.  Gives you the safety of *knowing*
that the filesystem was unexported before dropping the locks, and
preventing folks from shooting themselves in the foot.

The other option that was mentioned, a separate lockd for each fs, is
also a good idea - but would require a lot of coding no doubt, and
introduce more instability into what I already preceive as an unstable
NFS subsystem in Linux (I *refuse* to use Linux as an NFS server and
instead go with Solaris - I've had *really* bad experiences with Linux
NFS under load - but that's getting OT).