lockd: get rid of reference-counted NSM RPC clients

Currently we have reference-counted per-net NSM RPC client
which created on the first monitor request and destroyed
after the last unmonitor request. It's needed because
RPC client need to know 'utsname()->nodename', but utsname()
might be NULL when nsm_unmonitor() called.

So instead of holding the rpc client we could just save nodename
in struct nlm_host and pass it to the rpc_create().
Thus ther is no need in keeping rpc client until last
unmonitor request. We could create separate RPC clients
for each monitor/unmonitor requests.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

4 files changed, 16 insertions, 78 deletions

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index b5f3c3ab0d5f..d716c9993a26 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -161,6 +161,7 @@ static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni,
         host->h_nsmhandle  = nsm;
         host->h_addrbuf    = nsm->sm_addrbuf;
         host->net          = ni->net;
+        strlcpy(host->nodename, utsname()->nodename, sizeof(host->nodename));
 
 out:
         return host;
diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 6c05cd17e520..19166d4a8d31 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -42,7 +42,7 @@ struct nsm_args {
         u32                     proc;
 
         char                    *mon_name;
-        char                    *nodename;
+        const char              *nodename;
 };
 
 struct nsm_res {
@@ -86,69 +86,18 @@ static struct rpc_clnt *nsm_create(struct net *net, const char *nodename)
         return rpc_create(&args);
 }
 
-static struct rpc_clnt *nsm_client_set(struct lockd_net *ln,
-                struct rpc_clnt *clnt)
-{
-        spin_lock(&ln->nsm_clnt_lock);
-        if (ln->nsm_users == 0) {
-                if (clnt == NULL)
-                        goto out;
-                ln->nsm_clnt = clnt;
-        }
-        clnt = ln->nsm_clnt;
-        ln->nsm_users++;
-out:
-        spin_unlock(&ln->nsm_clnt_lock);
-        return clnt;
-}
-
-static struct rpc_clnt *nsm_client_get(struct net *net, const char *nodename)
-{
-        struct rpc_clnt *clnt, *new;
-        struct lockd_net *ln = net_generic(net, lockd_net_id);
-
-        clnt = nsm_client_set(ln, NULL);
-        if (clnt != NULL)
-                goto out;
-
-        clnt = new = nsm_create(net, nodename);
-        if (IS_ERR(clnt))
-                goto out;
-
-        clnt = nsm_client_set(ln, new);
-        if (clnt != new)
-                rpc_shutdown_client(new);
-out:
-        return clnt;
-}
-
-static void nsm_client_put(struct net *net)
-{
-        struct lockd_net *ln = net_generic(net, lockd_net_id);
-        struct rpc_clnt *clnt = NULL;
-
-        spin_lock(&ln->nsm_clnt_lock);
-        ln->nsm_users--;
-        if (ln->nsm_users == 0) {
-                clnt = ln->nsm_clnt;
-                ln->nsm_clnt = NULL;
-        }
-        spin_unlock(&ln->nsm_clnt_lock);
-        if (clnt != NULL)
-                rpc_shutdown_client(clnt);
-}
-
 static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
-                         struct rpc_clnt *clnt)
+                         const struct nlm_host *host)
 {
         int             status;
+        struct rpc_clnt *clnt;
         struct nsm_args args = {
                 .priv           = &nsm->sm_priv,
                 .prog           = NLM_PROGRAM,
                 .vers           = 3,
                 .proc           = NLMPROC_NSM_NOTIFY,
                 .mon_name       = nsm->sm_mon_name,
-                .nodename       = clnt->cl_nodename,
+                .nodename       = host->nodename,
         };
         struct rpc_message msg = {
                 .rpc_argp       = &args,
@@ -157,6 +106,13 @@ static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
 
         memset(res, 0, sizeof(*res));
 
+        clnt = nsm_create(host->net, host->nodename);
+        if (IS_ERR(clnt)) {
+                dprintk("lockd: failed to create NSM upcall transport, "
+                        "status=%ld, net=%p\n", PTR_ERR(clnt), host->net);
+                return PTR_ERR(clnt);
+        }
+
         msg.rpc_proc = &clnt->cl_procinfo[proc];
         status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
         if (status == -ECONNREFUSED) {
@@ -170,6 +126,8 @@ static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
                                 status);
         else
                 status = 0;
+
+        rpc_shutdown_client(clnt);
         return status;
 }
 
@@ -189,32 +147,19 @@ int nsm_monitor(const struct nlm_host *host)
         struct nsm_handle *nsm = host->h_nsmhandle;
         struct nsm_res  res;
         int             status;
-        struct rpc_clnt *clnt;
-        const char *nodename = NULL;
 
         dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
 
         if (nsm->sm_monitored)
                 return 0;
 
-        if (host->h_rpcclnt)
-                nodename = host->h_rpcclnt->cl_nodename;
-
         /*
          * Choose whether to record the caller_name or IP address of
          * this peer in the local rpc.statd's database.
          */
         nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
 
-        clnt = nsm_client_get(host->net, nodename);
-        if (IS_ERR(clnt)) {
-                status = PTR_ERR(clnt);
-                dprintk("lockd: failed to create NSM upcall transport, "
-                                "status=%d, net=%p\n", status, host->net);
-                return status;
-        }
-
-        status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, clnt);
+        status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host);
         if (unlikely(res.status != 0))
                 status = -EIO;
         if (unlikely(status < 0)) {
@@ -246,11 +191,9 @@ void nsm_unmonitor(const struct nlm_host *host)
 
         if (atomic_read(&nsm->sm_count) == 1
          && nsm->sm_monitored && !nsm->sm_sticky) {
-                struct lockd_net *ln = net_generic(host->net, lockd_net_id);
-
                 dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
 
-                status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, ln->nsm_clnt);
+                status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host);
                 if (res.status != 0)
                         status = -EIO;
                 if (status < 0)
@@ -258,8 +201,6 @@ void nsm_unmonitor(const struct nlm_host *host)
                                         nsm->sm_name);
                 else
                         nsm->sm_monitored = 0;
-
-                nsm_client_put(host->net);
         }
 }
 
diff --git a/fs/lockd/netns.h b/fs/lockd/netns.h
index 89fe011b1335..5426189406c1 100644
--- a/fs/lockd/netns.h
+++ b/fs/lockd/netns.h
@@ -12,9 +12,6 @@ struct lockd_net {
         struct delayed_work grace_period_end;
         struct lock_manager lockd_manager;
 
-        spinlock_t nsm_clnt_lock;
-        unsigned int nsm_users;
-        struct rpc_clnt *nsm_clnt;
         struct list_head nsm_handles;
 };
 
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 0dff13f41808..5f31ebd96c06 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -592,7 +592,6 @@ static int lockd_init_net(struct net *net)
         INIT_DELAYED_WORK(&ln->grace_period_end, grace_ender);
         INIT_LIST_HEAD(&ln->lockd_manager.list);
         ln->lockd_manager.block_opens = false;
-        spin_lock_init(&ln->nsm_clnt_lock);
         INIT_LIST_HEAD(&ln->nsm_handles);
         return 0;
 }