[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>

3 files changed, 24 insertions, 4 deletions

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 1bf384307d15..a1423c66df04 100644
--- a/fs/lockd/host.c
+++ b/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 --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 626b6c116a6d..709cf7c80545 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -47,6 +47,7 @@ nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res)
         }
 
         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, u32 *p, struct nsm_args *argp)
          * 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, utsname()->nodename)))
                 return ERR_PTR(-EIO);
         *p++ = htonl(argp->prog);
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 3cc369e5693f..a3b7602cd383 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -61,6 +61,7 @@ static DECLARE_WAIT_QUEUE_HEAD(lockd_exit);
 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_port, param_get_int,
                   &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.