[Cluster-devel] [RFC PATCH 0/3] NLM lock failover

[Wendy Cheng]

The uploaded patches implement NLM lock failover as discussed in:

http://www.redhat.com/archives/linux-cluster/2006-June/msg00050.html

[PATCH 1/3]
Add a new admin interface into current nfsd procfs filesystem to trigger 
NLM lock releasing logic. The command is invoked by echoing the server 
virtual IP address into /proc/fs/nfsd/nlm_unlock file as:

shell> cd /prod/fs/nfsd
shell> echo 10.10.1.1 > nlm_unlock
                                                                               

It is currently restricted to IPV4 addressing and the command should be 
invoked from the taken-over NFS server. To do list (not yet implemented) 
include:

1. IPv6 addessing enablement
2. Add "client:server" ip pair to allow NFS V4 lock failover as proposed 
by Andy Adamson (CITI).

[PATCH 2/3]
Add take-over server counter-part command into nfsd procfs interface to 
allow selectively setting of per (virtual) ip (lockd) grace period. It 
is also invoked by echoing the virtual IP into 
/proc/fs/nfsd/nlm_set_ip_grace file as:

shell> cd /proc/fs/nfsd
shell> echo 10.10.1.1 > nlm_set_ip_grace
                                                                                

It is also restricted to IPV4 addressing and the command is expected to 
be invoked from the take-over NFS server.

[PATCH 3/3]
This kernel patch has *not* been unit tested out yet and it needs to be 
paired with user mode nfs-utils changes (not ready in time for this 
RFC). It puts the taken-over IPv4 address in standard dot notation into 
the 3rd parameter of ha_callout program (see man rpc.statd for details) 
for "add-client" event. For "del-client", we would assume the monitored 
host should be removed from machine-wide lists, regardless server's 
interface.

Upon agree-ed on, we will integrate the changes into our cluster suite 
to start a full function verification test. Please comment.

-- Wendy