[PATCH] knfsd: lockd: optionally use hostnames for identifying peers

This patch adds the nsm_use_hostnames sysctl and module param.  If set, lockd
will use the client's name (as given in the NLM arguments) to find the NSM
handle.  This makes recovery work when the NFS peer is multi-homed, and the
reboot notification arrives from a different IP than the original lock calls.

Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 3cc369e..a3b7602 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -61,6 +61,7 @@
 static unsigned long		nlm_grace_period;
 static unsigned long		nlm_timeout = LOCKD_DFLT_TIMEO;
 static int			nlm_udpport, nlm_tcpport;
+int				nsm_use_hostnames = 0;
 
 /*
  * Constants needed for the sysctl interface.
@@ -395,6 +396,14 @@
 		.extra1		= (int *) &nlm_port_min,
 		.extra2		= (int *) &nlm_port_max,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nsm_use_hostnames",
+		.data		= &nsm_use_hostnames,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 	{ .ctl_name = 0 }
 };
 
@@ -483,6 +492,7 @@
 		  &nlm_udpport, 0644);
 module_param_call(nlm_tcpport, param_set_port, param_get_int,
 		  &nlm_tcpport, 0644);
+module_param(nsm_use_hostnames, bool, 0644);
 
 /*
  * Initialising and terminating the module.