Merge tag 'nfsd-4.4' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Apologies for coming a little late in the merge window.  Fortunately
  this is another fairly quiet one:

  Mainly smaller bugfixes and cleanup.  We're still finding some bugs
  from the breakup of the big NFSv4 state lock in 3.17 -- thanks
  especially to Andrew Elble and Jeff Layton for tracking down some of
  the remaining races"

* tag 'nfsd-4.4' of git://linux-nfs.org/~bfields/linux:
  svcrpc: document lack of some memory barriers
  nfsd: fix race with open / open upgrade stateids
  nfsd: eliminate sending duplicate and repeated delegations
  nfsd: remove recurring workqueue job to clean DRC
  SUNRPC: drop stale comment in svc_setup_socket()
  nfsd: ensure that seqid morphing operations are atomic wrt to copies
  nfsd: serialize layout stateid morphing operations
  nfsd: improve client_has_state to check for unused openowners
  nfsd: fix clid_inuse on mount with security change
  sunrpc/cache: make cache flushing more reliable.
  nfsd: move include of state.h from trace.c to trace.h
  sunrpc: avoid warning in gss_key_timeout
  lockd: get rid of reference-counted NSM RPC clients
  SUNRPC: Use MSG_SENDPAGE_NOTLAST when calling sendpage()
  lockd: create NSM handles per net namespace
  nfsd: switch unsigned char flags in svc_fh to bools
  nfsd: move svc_fh->fh_maxsize to just after fh_handle
  nfsd: drop null test before destroy functions
  nfsd: serialize state seqid morphing operations

19 files changed, 316 insertions, 248 deletions

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 969d589c848d..d716c9993a26 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -116,7 +116,7 @@ static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni,
 		atomic_inc(&nsm->sm_count);
 	else {
 		host = NULL;
-		nsm = nsm_get_handle(ni->sap, ni->salen,
+		nsm = nsm_get_handle(ni->net, ni->sap, ni->salen,
 					ni->hostname, ni->hostname_len);
 		if (unlikely(nsm == NULL)) {
 			dprintk("lockd: %s failed; no nsm handle\n",
@@ -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;
@@ -534,17 +535,18 @@ static struct nlm_host *next_host_state(struct hlist_head *cache,
 
 /**
  * nlm_host_rebooted - Release all resources held by rebooted host
+ * @net:  network namespace
  * @info: pointer to decoded results of NLM_SM_NOTIFY call
  *
  * We were notified that the specified host has rebooted.  Release
  * all resources held by that peer.
  */
-void nlm_host_rebooted(const struct nlm_reboot *info)
+void nlm_host_rebooted(const struct net *net, const struct nlm_reboot *info)
 {
 	struct nsm_handle *nsm;
 	struct nlm_host	*host;
 
-	nsm = nsm_reboot_lookup(info);
+	nsm = nsm_reboot_lookup(net, info);
 	if (unlikely(nsm == NULL))
 		return;
 
diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 47a32b6d9b90..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 {
@@ -51,7 +51,6 @@ struct nsm_res {
 };
 
 static const struct rpc_program	nsm_program;
-static				LIST_HEAD(nsm_handles);
 static				DEFINE_SPINLOCK(nsm_lock);
 
 /*
@@ -87,69 +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,
@@ -158,6 +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) {
@@ -171,6 +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;
 }
 
@@ -190,32 +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)) {
@@ -247,11 +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)
@@ -259,38 +201,38 @@ void nsm_unmonitor(const struct nlm_host *host)
 					nsm->sm_name);
 		else
 			nsm->sm_monitored = 0;
-
-		nsm_client_put(host->net);
 	}
 }
 
-static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
-					      const size_t len)
+static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
+					const char *hostname, const size_t len)
 {
 	struct nsm_handle *nsm;
 
-	list_for_each_entry(nsm, &nsm_handles, sm_link)
+	list_for_each_entry(nsm, nsm_handles, sm_link)
 		if (strlen(nsm->sm_name) == len &&
 		    memcmp(nsm->sm_name, hostname, len) == 0)
 			return nsm;
 	return NULL;
 }
 
-static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
+static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
+					const struct sockaddr *sap)
 {
 	struct nsm_handle *nsm;
 
-	list_for_each_entry(nsm, &nsm_handles, sm_link)
+	list_for_each_entry(nsm, nsm_handles, sm_link)
 		if (rpc_cmp_addr(nsm_addr(nsm), sap))
 			return nsm;
 	return NULL;
 }
 
-static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
+static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
+					const struct nsm_private *priv)
 {
 	struct nsm_handle *nsm;
 
-	list_for_each_entry(nsm, &nsm_handles, sm_link)
+	list_for_each_entry(nsm, nsm_handles, sm_link)
 		if (memcmp(nsm->sm_priv.data, priv->data,
 					sizeof(priv->data)) == 0)
 			return nsm;
@@ -353,6 +295,7 @@ static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
 
 /**
  * nsm_get_handle - Find or create a cached nsm_handle
+ * @net: network namespace
  * @sap: pointer to socket address of handle to find
  * @salen: length of socket address
  * @hostname: pointer to C string containing hostname to find
@@ -365,11 +308,13 @@ static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
  * @hostname cannot be found in the handle cache.  Returns NULL if
  * an error occurs.
  */
-struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
+struct nsm_handle *nsm_get_handle(const struct net *net,
+				  const struct sockaddr *sap,
 				  const size_t salen, const char *hostname,
 				  const size_t hostname_len)
 {
 	struct nsm_handle *cached, *new = NULL;
+	struct lockd_net *ln = net_generic(net, lockd_net_id);
 
 	if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 		if (printk_ratelimit()) {
@@ -384,9 +329,10 @@ retry:
 	spin_lock(&nsm_lock);
 
 	if (nsm_use_hostnames && hostname != NULL)
-		cached = nsm_lookup_hostname(hostname, hostname_len);
+		cached = nsm_lookup_hostname(&ln->nsm_handles,
+					hostname, hostname_len);
 	else
-		cached = nsm_lookup_addr(sap);
+		cached = nsm_lookup_addr(&ln->nsm_handles, sap);
 
 	if (cached != NULL) {
 		atomic_inc(&cached->sm_count);
@@ -400,7 +346,7 @@ retry:
 	}
 
 	if (new != NULL) {
-		list_add(&new->sm_link, &nsm_handles);
+		list_add(&new->sm_link, &ln->nsm_handles);
 		spin_unlock(&nsm_lock);
 		dprintk("lockd: created nsm_handle for %s (%s)\n",
 				new->sm_name, new->sm_addrbuf);
@@ -417,19 +363,22 @@ retry:
 
 /**
  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
+ * @net:  network namespace
  * @info: pointer to NLMPROC_SM_NOTIFY arguments
  *
  * Returns a matching nsm_handle if found in the nsm cache. The returned
  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
  * error occurred.
  */
-struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
+struct nsm_handle *nsm_reboot_lookup(const struct net *net,
+				const struct nlm_reboot *info)
 {
 	struct nsm_handle *cached;
+	struct lockd_net *ln = net_generic(net, lockd_net_id);
 
 	spin_lock(&nsm_lock);
 
-	cached = nsm_lookup_priv(&info->priv);
+	cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
 	if (unlikely(cached == NULL)) {
 		spin_unlock(&nsm_lock);
 		dprintk("lockd: never saw rebooted peer '%.*s' before\n",
diff --git a/fs/lockd/netns.h b/fs/lockd/netns.h
index 097bfa3adb1c..5426189406c1 100644
--- a/fs/lockd/netns.h
+++ b/fs/lockd/netns.h
@@ -12,9 +12,7 @@ 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;
 };
 
 extern int lockd_net_id;
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index d678bcc3cbcb..5f31ebd96c06 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -592,7 +592,7 @@ 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;
 }
 
diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index b147d1ae71fd..09c576f26c7b 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -421,7 +421,7 @@ nlm4svc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
 		return rpc_system_err;
 	}
 
-	nlm_host_rebooted(argp);
+	nlm_host_rebooted(SVC_NET(rqstp), argp);
 	return rpc_success;
 }
 
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 21171f0c6477..fb26b9f522e7 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -464,7 +464,7 @@ nlmsvc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
 		return rpc_system_err;
 	}
 
-	nlm_host_rebooted(argp);
+	nlm_host_rebooted(SVC_NET(rqstp), argp);
 	return rpc_success;
 }
 
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index f6e7cbabac5a..00575d776d91 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -262,11 +262,11 @@ void fill_post_wcc(struct svc_fh *fhp)
 	err = fh_getattr(fhp, &fhp->fh_post_attr);
 	fhp->fh_post_change = d_inode(fhp->fh_dentry)->i_version;
 	if (err) {
-		fhp->fh_post_saved = 0;
+		fhp->fh_post_saved = false;
 		/* Grab the ctime anyway - set_change_info might use it */
 		fhp->fh_post_attr.ctime = d_inode(fhp->fh_dentry)->i_ctime;
 	} else
-		fhp->fh_post_saved = 1;
+		fhp->fh_post_saved = true;
 }
 
 /*
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index ebf90e487c75..9ffef06b30d5 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -201,6 +201,7 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate,
 	INIT_LIST_HEAD(&ls->ls_perfile);
 	spin_lock_init(&ls->ls_lock);
 	INIT_LIST_HEAD(&ls->ls_layouts);
+	mutex_init(&ls->ls_mutex);
 	ls->ls_layout_type = layout_type;
 	nfsd4_init_cb(&ls->ls_recall, clp, &nfsd4_cb_layout_ops,
 			NFSPROC4_CLNT_CB_LAYOUT);
@@ -262,19 +263,23 @@ nfsd4_preprocess_layout_stateid(struct svc_rqst *rqstp,
 		status = nfserr_jukebox;
 		if (!ls)
 			goto out;
+		mutex_lock(&ls->ls_mutex);
 	} else {
 		ls = container_of(stid, struct nfs4_layout_stateid, ls_stid);
 
 		status = nfserr_bad_stateid;
+		mutex_lock(&ls->ls_mutex);
 		if (stateid->si_generation > stid->sc_stateid.si_generation)
-			goto out_put_stid;
+			goto out_unlock_stid;
 		if (layout_type != ls->ls_layout_type)
-			goto out_put_stid;
+			goto out_unlock_stid;
 	}
 
 	*lsp = ls;
 	return 0;
 
+out_unlock_stid:
+	mutex_unlock(&ls->ls_mutex);
 out_put_stid:
 	nfs4_put_stid(stid);
 out:
@@ -296,8 +301,6 @@ nfsd4_recall_file_layout(struct nfs4_layout_stateid *ls)
 	trace_layout_recall(&ls->ls_stid.sc_stateid);
 
 	atomic_inc(&ls->ls_stid.sc_count);
-	update_stateid(&ls->ls_stid.sc_stateid);
-	memcpy(&ls->ls_recall_sid, &ls->ls_stid.sc_stateid, sizeof(stateid_t));
 	nfsd4_run_cb(&ls->ls_recall);
 
 out_unlock:
@@ -406,8 +409,7 @@ nfsd4_insert_layout(struct nfsd4_layoutget *lgp, struct nfs4_layout_stateid *ls)
 	list_add_tail(&new->lo_perstate, &ls->ls_layouts);
 	new = NULL;
 done:
-	update_stateid(&ls->ls_stid.sc_stateid);
-	memcpy(&lgp->lg_sid, &ls->ls_stid.sc_stateid, sizeof(stateid_t));
+	nfs4_inc_and_copy_stateid(&lgp->lg_sid, &ls->ls_stid);
 	spin_unlock(&ls->ls_lock);
 out:
 	spin_unlock(&fp->fi_lock);
@@ -481,11 +483,8 @@ nfsd4_return_file_layouts(struct svc_rqst *rqstp,
 		}
 	}
 	if (!list_empty(&ls->ls_layouts)) {
-		if (found) {
-			update_stateid(&ls->ls_stid.sc_stateid);
-			memcpy(&lrp->lr_sid, &ls->ls_stid.sc_stateid,
-				sizeof(stateid_t));
-		}
+		if (found)
+			nfs4_inc_and_copy_stateid(&lrp->lr_sid, &ls->ls_stid);
 		lrp->lrs_present = 1;
 	} else {
 		trace_layoutstate_unhash(&ls->ls_stid.sc_stateid);
@@ -494,6 +493,7 @@ nfsd4_return_file_layouts(struct svc_rqst *rqstp,
 	}
 	spin_unlock(&ls->ls_lock);
 
+	mutex_unlock(&ls->ls_mutex);
 	nfs4_put_stid(&ls->ls_stid);
 	nfsd4_free_layouts(&reaplist);
 	return nfs_ok;
@@ -608,6 +608,16 @@ nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
 	}
 }
 
+static void
+nfsd4_cb_layout_prepare(struct nfsd4_callback *cb)
+{
+	struct nfs4_layout_stateid *ls =
+		container_of(cb, struct nfs4_layout_stateid, ls_recall);
+
+	mutex_lock(&ls->ls_mutex);
+	nfs4_inc_and_copy_stateid(&ls->ls_recall_sid, &ls->ls_stid);
+}
+
 static int
 nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
 {
@@ -649,12 +659,14 @@ nfsd4_cb_layout_release(struct nfsd4_callback *cb)
 
 	trace_layout_recall_release(&ls->ls_stid.sc_stateid);
 
+	mutex_unlock(&ls->ls_mutex);
 	nfsd4_return_all_layouts(ls, &reaplist);
 	nfsd4_free_layouts(&reaplist);
 	nfs4_put_stid(&ls->ls_stid);
 }
 
 static struct nfsd4_callback_ops nfsd4_cb_layout_ops = {
+	.prepare	= nfsd4_cb_layout_prepare,
 	.done		= nfsd4_cb_layout_done,
 	.release	= nfsd4_cb_layout_release,
 };
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 4ce6b97b31ad..a9f096c7e99f 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1309,6 +1309,7 @@ nfsd4_layoutget(struct svc_rqst *rqstp,
 	nfserr = nfsd4_insert_layout(lgp, ls);
 
 out_put_stid:
+	mutex_unlock(&ls->ls_mutex);
 	nfs4_put_stid(&ls->ls_stid);
 out:
 	return nfserr;
@@ -1362,6 +1363,9 @@ nfsd4_layoutcommit(struct svc_rqst *rqstp,
 		goto out;
 	}
 
+	/* LAYOUTCOMMIT does not require any serialization */
+	mutex_unlock(&ls->ls_mutex);
+
 	if (new_size > i_size_read(inode)) {
 		lcp->lc_size_chg = 1;
 		lcp->lc_newsize = new_size;
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 0f1d5691b795..6b800b5b8fed 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -575,6 +575,7 @@ struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl,
 	stid->sc_stateid.si_opaque.so_clid = cl->cl_clientid;
 	/* Will be incremented before return to client: */
 	atomic_set(&stid->sc_count, 1);
+	spin_lock_init(&stid->sc_lock);
 
 	/*
 	 * It shouldn't be a problem to reuse an opaque stateid value.
@@ -745,6 +746,18 @@ nfs4_put_stid(struct nfs4_stid *s)
 		put_nfs4_file(fp);
 }
 
+void
+nfs4_inc_and_copy_stateid(stateid_t *dst, struct nfs4_stid *stid)
+{
+	stateid_t *src = &stid->sc_stateid;
+
+	spin_lock(&stid->sc_lock);
+	if (unlikely(++src->si_generation == 0))
+		src->si_generation = 1;
+	memcpy(dst, src, sizeof(*dst));
+	spin_unlock(&stid->sc_lock);
+}
+
 static void nfs4_put_deleg_lease(struct nfs4_file *fp)
 {
 	struct file *filp = NULL;
@@ -765,16 +778,68 @@ void nfs4_unhash_stid(struct nfs4_stid *s)
 	s->sc_type = 0;
 }
 
-static void
+/**
+ * nfs4_get_existing_delegation - Discover if this delegation already exists
+ * @clp:     a pointer to the nfs4_client we're granting a delegation to
+ * @fp:      a pointer to the nfs4_file we're granting a delegation on
+ *
+ * Return:
+ *      On success: NULL if an existing delegation was not found.
+ *
+ *      On error: -EAGAIN if one was previously granted to this nfs4_client
+ *                 for this nfs4_file.
+ *
+ */
+
+static int
+nfs4_get_existing_delegation(struct nfs4_client *clp, struct nfs4_file *fp)
+{
+	struct nfs4_delegation *searchdp = NULL;
+	struct nfs4_client *searchclp = NULL;
+
+	lockdep_assert_held(&state_lock);
+	lockdep_assert_held(&fp->fi_lock);
+
+	list_for_each_entry(searchdp, &fp->fi_delegations, dl_perfile) {
+		searchclp = searchdp->dl_stid.sc_client;
+		if (clp == searchclp) {
+			return -EAGAIN;
+		}
+	}
+	return 0;
+}
+
+/**
+ * hash_delegation_locked - Add a delegation to the appropriate lists
+ * @dp:     a pointer to the nfs4_delegation we are adding.
+ * @fp:     a pointer to the nfs4_file we're granting a delegation on
+ *
+ * Return:
+ *      On success: NULL if the delegation was successfully hashed.
+ *
+ *      On error: -EAGAIN if one was previously granted to this
+ *                 nfs4_client for this nfs4_file. Delegation is not hashed.
+ *
+ */
+
+static int
 hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
 {
+	int status;
+	struct nfs4_client *clp = dp->dl_stid.sc_client;
+
 	lockdep_assert_held(&state_lock);
 	lockdep_assert_held(&fp->fi_lock);
 
+	status = nfs4_get_existing_delegation(clp, fp);
+	if (status)
+		return status;
+	++fp->fi_delegees;
 	atomic_inc(&dp->dl_stid.sc_count);
 	dp->dl_stid.sc_type = NFS4_DELEG_STID;
 	list_add(&dp->dl_perfile, &fp->fi_delegations);
-	list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);
+	list_add(&dp->dl_perclnt, &clp->cl_delegations);
+	return 0;
 }
 
 static bool
@@ -2256,15 +2321,20 @@ nfsd4_set_ex_flags(struct nfs4_client *new, struct nfsd4_exchange_id *clid)
 	clid->flags = new->cl_exchange_flags;
 }
 
+static bool client_has_openowners(struct nfs4_client *clp)
+{
+	struct nfs4_openowner *oo;
+
+	list_for_each_entry(oo, &clp->cl_openowners, oo_perclient) {
+		if (!list_empty(&oo->oo_owner.so_stateids))
+			return true;
+	}
+	return false;
+}
+
 static bool client_has_state(struct nfs4_client *clp)
 {
-	/*
-	 * Note clp->cl_openowners check isn't quite right: there's no
-	 * need to count owners without stateid's.
-	 *
-	 * Also note we should probably be using this in 4.0 case too.
-	 */
-	return !list_empty(&clp->cl_openowners)
+	return client_has_openowners(clp)
 #ifdef CONFIG_NFSD_PNFS
 		|| !list_empty(&clp->cl_lo_states)
 #endif
@@ -3049,7 +3119,7 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	/* Cases below refer to rfc 3530 section 14.2.33: */
 	spin_lock(&nn->client_lock);
 	conf = find_confirmed_client_by_name(&clname, nn);
-	if (conf) {
+	if (conf && client_has_state(conf)) {
 		/* case 0: */
 		status = nfserr_clid_inuse;
 		if (clp_used_exchangeid(conf))
@@ -3136,6 +3206,11 @@ nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
 	} else { /* case 3: normal case; new or rebooted client */
 		old = find_confirmed_client_by_name(&unconf->cl_name, nn);
 		if (old) {
+			status = nfserr_clid_inuse;
+			if (client_has_state(old)
+					&& !same_creds(&unconf->cl_cred,
+							&old->cl_cred))
+				goto out;
 			status = mark_client_expired_locked(old);
 			if (status) {
 				old = NULL;
@@ -3317,6 +3392,27 @@ static const struct nfs4_stateowner_operations openowner_ops = {
 	.so_free =	nfs4_free_openowner,
 };
 
+static struct nfs4_ol_stateid *
+nfsd4_find_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
+{
+	struct nfs4_ol_stateid *local, *ret = NULL;
+	struct nfs4_openowner *oo = open->op_openowner;
+
+	lockdep_assert_held(&fp->fi_lock);
+
+	list_for_each_entry(local, &fp->fi_stateids, st_perfile) {
+		/* ignore lock owners */
+		if (local->st_stateowner->so_is_open_owner == 0)
+			continue;
+		if (local->st_stateowner == &oo->oo_owner) {
+			ret = local;
+			atomic_inc(&ret->st_stid.sc_count);
+			break;
+		}
+	}
+	return ret;
+}
+
 static struct nfs4_openowner *
 alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
 			   struct nfsd4_compound_state *cstate)
@@ -3348,9 +3444,20 @@ alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
 	return ret;
 }
 
-static void init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) {
+static struct nfs4_ol_stateid *
+init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
+		struct nfsd4_open *open)
+{
+
 	struct nfs4_openowner *oo = open->op_openowner;
+	struct nfs4_ol_stateid *retstp = NULL;
 
+	spin_lock(&oo->oo_owner.so_client->cl_lock);
+	spin_lock(&fp->fi_lock);
+
+	retstp = nfsd4_find_existing_open(fp, open);
+	if (retstp)
+		goto out_unlock;
 	atomic_inc(&stp->st_stid.sc_count);
 	stp->st_stid.sc_type = NFS4_OPEN_STID;
 	INIT_LIST_HEAD(&stp->st_locks);
@@ -3360,12 +3467,14 @@ static void init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
 	stp->st_access_bmap = 0;
 	stp->st_deny_bmap = 0;
 	stp->st_openstp = NULL;
-	spin_lock(&oo->oo_owner.so_client->cl_lock);
+	init_rwsem(&stp->st_rwsem);
 	list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
-	spin_lock(&fp->fi_lock);
 	list_add(&stp->st_perfile, &fp->fi_stateids);
+
+out_unlock:
 	spin_unlock(&fp->fi_lock);
 	spin_unlock(&oo->oo_owner.so_client->cl_lock);
+	return retstp;
 }
 
 /*
@@ -3776,27 +3885,6 @@ out:
 	return nfs_ok;
 }
 
-static struct nfs4_ol_stateid *
-nfsd4_find_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
-{
-	struct nfs4_ol_stateid *local, *ret = NULL;
-	struct nfs4_openowner *oo = open->op_openowner;
-
-	spin_lock(&fp->fi_lock);
-	list_for_each_entry(local, &fp->fi_stateids, st_perfile) {
-		/* ignore lock owners */
-		if (local->st_stateowner->so_is_open_owner == 0)
-			continue;
-		if (local->st_stateowner == &oo->oo_owner) {
-			ret = local;
-			atomic_inc(&ret->st_stid.sc_count);
-			break;
-		}
-	}
-	spin_unlock(&fp->fi_lock);
-	return ret;
-}
-
 static inline int nfs4_access_to_access(u32 nfs4_access)
 {
 	int flags = 0;
@@ -3945,6 +4033,18 @@ static struct file_lock *nfs4_alloc_init_lease(struct nfs4_file *fp, int flag)
 	return fl;
 }
 
+/**
+ * nfs4_setlease - Obtain a delegation by requesting lease from vfs layer
+ * @dp:   a pointer to the nfs4_delegation we're adding.
+ *
+ * Return:
+ *      On success: Return code will be 0 on success.
+ *
+ *      On error: -EAGAIN if there was an existing delegation.
+ *                 nonzero if there is an error in other cases.
+ *
+ */
+
 static int nfs4_setlease(struct nfs4_delegation *dp)
 {
 	struct nfs4_file *fp = dp->dl_stid.sc_file;
@@ -3976,16 +4076,19 @@ static int nfs4_setlease(struct nfs4_delegation *dp)
 		goto out_unlock;
 	/* Race breaker */
 	if (fp->fi_deleg_file) {
-		status = 0;
-		++fp->fi_delegees;
-		hash_delegation_locked(dp, fp);
+		status = hash_delegation_locked(dp, fp);
 		goto out_unlock;
 	}
 	fp->fi_deleg_file = filp;
-	fp->fi_delegees = 1;
-	hash_delegation_locked(dp, fp);
+	fp->fi_delegees = 0;
+	status = hash_delegation_locked(dp, fp);
 	spin_unlock(&fp->fi_lock);
 	spin_unlock(&state_lock);
+	if (status) {
+		/* Should never happen, this is a new fi_deleg_file  */
+		WARN_ON_ONCE(1);
+		goto out_fput;
+	}
 	return 0;
 out_unlock:
 	spin_unlock(&fp->fi_lock);
@@ -4005,6 +4108,15 @@ nfs4_set_delegation(struct nfs4_client *clp, struct svc_fh *fh,
 	if (fp->fi_had_conflict)
 		return ERR_PTR(-EAGAIN);
 
+	spin_lock(&state_lock);
+	spin_lock(&fp->fi_lock);
+	status = nfs4_get_existing_delegation(clp, fp);
+	spin_unlock(&fp->fi_lock);
+	spin_unlock(&state_lock);
+
+	if (status)
+		return ERR_PTR(status);
+
 	dp = alloc_init_deleg(clp, fh, odstate);
 	if (!dp)
 		return ERR_PTR(-ENOMEM);
@@ -4023,9 +4135,7 @@ nfs4_set_delegation(struct nfs4_client *clp, struct svc_fh *fh,
 		status = -EAGAIN;
 		goto out_unlock;
 	}
-	++fp->fi_delegees;
-	hash_delegation_locked(dp, fp);
-	status = 0;
+	status = hash_delegation_locked(dp, fp);
 out_unlock:
 	spin_unlock(&fp->fi_lock);
 	spin_unlock(&state_lock);
@@ -4160,6 +4270,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 	struct nfs4_client *cl = open->op_openowner->oo_owner.so_client;
 	struct nfs4_file *fp = NULL;
 	struct nfs4_ol_stateid *stp = NULL;
+	struct nfs4_ol_stateid *swapstp = NULL;
 	struct nfs4_delegation *dp = NULL;
 	__be32 status;
 
@@ -4173,7 +4284,9 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 		status = nfs4_check_deleg(cl, open, &dp);
 		if (status)
 			goto out;
+		spin_lock(&fp->fi_lock);
 		stp = nfsd4_find_existing_open(fp, open);
+		spin_unlock(&fp->fi_lock);
 	} else {
 		open->op_file = NULL;
 		status = nfserr_bad_stateid;
@@ -4187,15 +4300,32 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 	 */
 	if (stp) {
 		/* Stateid was found, this is an OPEN upgrade */
+		down_read(&stp->st_rwsem);
 		status = nfs4_upgrade_open(rqstp, fp, current_fh, stp, open);
-		if (status)
+		if (status) {
+			up_read(&stp->st_rwsem);
 			goto out;
+		}
 	} else {
 		stp = open->op_stp;
 		open->op_stp = NULL;
-		init_open_stateid(stp, fp, open);
+		swapstp = init_open_stateid(stp, fp, open);
+		if (swapstp) {
+			nfs4_put_stid(&stp->st_stid);
+			stp = swapstp;
+			down_read(&stp->st_rwsem);
+			status = nfs4_upgrade_open(rqstp, fp, current_fh,
+						stp, open);
+			if (status) {
+				up_read(&stp->st_rwsem);
+				goto out;
+			}
+			goto upgrade_out;