From: Olaf Kirch <okir@suse.de>

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>
---

 fs/lockd/host.c                |    6 +++++-
 fs/lockd/mon.c                 |   12 +++++++++---
 fs/lockd/svc.c                 |   10 ++++++++++
 include/linux/lockd/lockd.h    |    1 +
 include/linux/lockd/sm_inter.h |    2 ++
 5 files changed, 27 insertions(+), 4 deletions(-)

diff -puN fs/lockd/host.c~knfsd-lockd-optionally-use-hostnames-for-identifying-peers fs/lockd/host.c
--- a/fs/lockd/host.c~knfsd-lockd-optionally-use-hostnames-for-identifying-peers
+++ a/fs/lockd/host.c
@@ -462,7 +462,11 @@ __nsm_find(const struct sockaddr_in *sin
 	list_for_each(pos, &nsm_handles) {
 		nsm = list_entry(pos, struct nsm_handle, sm_link);
 
-		if (!nlm_cmp_addr(&nsm->sm_addr, sin))
+		if (hostname && nsm_use_hostnames) {
+			if (strlen(nsm->sm_name) != hostname_len
+			 || memcmp(nsm->sm_name, hostname, hostname_len))
+				continue;
+		} else if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 			continue;
 		atomic_inc(&nsm->sm_count);
 		goto out;
diff -puN fs/lockd/mon.c~knfsd-lockd-optionally-use-hostnames-for-identifying-peers fs/lockd/mon.c
--- a/fs/lockd/mon.c~knfsd-lockd-optionally-use-hostnames-for-identifying-peers
+++ a/fs/lockd/mon.c
@@ -47,6 +47,7 @@ nsm_mon_unmon(struct nsm_handle *nsm, u3
 	}
 
 	memset(&args, 0, sizeof(args));
+	args.mon_name = nsm->sm_name;
 	args.addr = nsm->sm_addr.sin_addr.s_addr;
 	args.prog = NLM_PROGRAM;
 	args.vers = 3;
@@ -150,7 +151,7 @@ nsm_create(void)
 static u32 *
 xdr_encode_common(struct rpc_rqst *rqstp, u32 *p, struct nsm_args *argp)
 {
-	char	buffer[20];
+	char	buffer[20], *name;
 
 	/*
 	 * Use the dotted-quad IP address of the remote host as
@@ -158,8 +159,13 @@ xdr_encode_common(struct rpc_rqst *rqstp
 	 * hostname first for whatever remote hostname it receives,
 	 * so this works alright.
 	 */
-	sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(argp->addr));
-	if (!(p = xdr_encode_string(p, buffer))
+	if (nsm_use_hostnames) {
+		name = argp->mon_name;
+	} else {
+		sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(argp->addr));
+		name = buffer;
+	}
+	if (!(p = xdr_encode_string(p, name))
 	 || !(p = xdr_encode_string(p, system_utsname.nodename)))
 		return ERR_PTR(-EIO);
 	*p++ = htonl(argp->prog);
diff -puN fs/lockd/svc.c~knfsd-lockd-optionally-use-hostnames-for-identifying-peers fs/lockd/svc.c
--- a/fs/lockd/svc.c~knfsd-lockd-optionally-use-hostnames-for-identifying-peers
+++ a/fs/lockd/svc.c
@@ -61,6 +61,7 @@ static DECLARE_WAIT_QUEUE_HEAD(lockd_exi
 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 @@ static ctl_table nlm_sysctls[] = {
 		.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 @@ module_param_call(nlm_udpport, param_set
 		  &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.
diff -puN include/linux/lockd/lockd.h~knfsd-lockd-optionally-use-hostnames-for-identifying-peers include/linux/lockd/lockd.h
--- a/include/linux/lockd/lockd.h~knfsd-lockd-optionally-use-hostnames-for-identifying-peers
+++ a/include/linux/lockd/lockd.h
@@ -142,6 +142,7 @@ extern struct svc_procedure	nlmsvc_proce
 #endif
 extern int			nlmsvc_grace_period;
 extern unsigned long		nlmsvc_timeout;
+extern int			nsm_use_hostnames;
 
 /*
  * Lockd client functions
diff -puN include/linux/lockd/sm_inter.h~knfsd-lockd-optionally-use-hostnames-for-identifying-peers include/linux/lockd/sm_inter.h
--- a/include/linux/lockd/sm_inter.h~knfsd-lockd-optionally-use-hostnames-for-identifying-peers
+++ a/include/linux/lockd/sm_inter.h
@@ -28,6 +28,8 @@ struct nsm_args {
 	u32		prog;		/* RPC callback info */
 	u32		vers;
 	u32		proc;
+
+	char *		mon_name;
 };
 
 /*
_