Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2661 insertions, 0 deletions

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
new file mode 100644
index 000000000..30576a10a
--- /dev/null
+++ b/fs/nfs/nfs4state.c
@@ -0,0 +1,2661 @@
+/*
+ *  fs/nfs/nfs4state.c
+ *
+ *  Client-side XDR for NFSv4.
+ *
+ *  Copyright (c) 2002 The Regents of the University of Michigan.
+ *  All rights reserved.
+ *
+ *  Kendrick Smith <kmsmith@umich.edu>
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the University nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Implementation of the NFSv4 state model.  For the time being,
+ * this is minimal, but will be made much more complex in a
+ * subsequent patch.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/nfs_fs.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/ratelimit.h>
+#include <linux/workqueue.h>
+#include <linux/bitops.h>
+#include <linux/jiffies.h>
+#include <linux/sched/mm.h>
+
+#include <linux/sunrpc/clnt.h>
+
+#include "nfs4_fs.h"
+#include "callback.h"
+#include "delegation.h"
+#include "internal.h"
+#include "nfs4idmap.h"
+#include "nfs4session.h"
+#include "pnfs.h"
+#include "netns.h"
+
+#define NFSDBG_FACILITY		NFSDBG_STATE
+
+#define OPENOWNER_POOL_SIZE	8
+
+const nfs4_stateid zero_stateid = {
+	{ .data = { 0 } },
+	.type = NFS4_SPECIAL_STATEID_TYPE,
+};
+const nfs4_stateid invalid_stateid = {
+	{
+		/* Funky initialiser keeps older gcc versions happy */
+		.data = { 0xff, 0xff, 0xff, 0xff, 0 },
+	},
+	.type = NFS4_INVALID_STATEID_TYPE,
+};
+
+const nfs4_stateid current_stateid = {
+	{
+		/* Funky initialiser keeps older gcc versions happy */
+		.data = { 0x0, 0x0, 0x0, 0x1, 0 },
+	},
+	.type = NFS4_SPECIAL_STATEID_TYPE,
+};
+
+static DEFINE_MUTEX(nfs_clid_init_mutex);
+
+int nfs4_init_clientid(struct nfs_client *clp, struct rpc_cred *cred)
+{
+	struct nfs4_setclientid_res clid = {
+		.clientid = clp->cl_clientid,
+		.confirm = clp->cl_confirm,
+	};
+	unsigned short port;
+	int status;
+	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
+
+	if (test_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state))
+		goto do_confirm;
+	port = nn->nfs_callback_tcpport;
+	if (clp->cl_addr.ss_family == AF_INET6)
+		port = nn->nfs_callback_tcpport6;
+
+	status = nfs4_proc_setclientid(clp, NFS4_CALLBACK, port, cred, &clid);
+	if (status != 0)
+		goto out;
+	clp->cl_clientid = clid.clientid;
+	clp->cl_confirm = clid.confirm;
+	set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+do_confirm:
+	status = nfs4_proc_setclientid_confirm(clp, &clid, cred);
+	if (status != 0)
+		goto out;
+	clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+	nfs4_schedule_state_renewal(clp);
+out:
+	return status;
+}
+
+/**
+ * nfs40_discover_server_trunking - Detect server IP address trunking (mv0)
+ *
+ * @clp: nfs_client under test
+ * @result: OUT: found nfs_client, or clp
+ * @cred: credential to use for trunking test
+ *
+ * Returns zero, a negative errno, or a negative NFS4ERR status.
+ * If zero is returned, an nfs_client pointer is planted in
+ * "result".
+ *
+ * Note: The returned client may not yet be marked ready.
+ */
+int nfs40_discover_server_trunking(struct nfs_client *clp,
+				   struct nfs_client **result,
+				   struct rpc_cred *cred)
+{
+	struct nfs4_setclientid_res clid = {
+		.clientid = clp->cl_clientid,
+		.confirm = clp->cl_confirm,
+	};
+	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
+	unsigned short port;
+	int status;
+
+	port = nn->nfs_callback_tcpport;
+	if (clp->cl_addr.ss_family == AF_INET6)
+		port = nn->nfs_callback_tcpport6;
+
+	status = nfs4_proc_setclientid(clp, NFS4_CALLBACK, port, cred, &clid);
+	if (status != 0)
+		goto out;
+	clp->cl_clientid = clid.clientid;
+	clp->cl_confirm = clid.confirm;
+
+	status = nfs40_walk_client_list(clp, result, cred);
+	if (status == 0) {
+		/* Sustain the lease, even if it's empty.  If the clientid4
+		 * goes stale it's of no use for trunking discovery. */
+		nfs4_schedule_state_renewal(*result);
+
+		/* If the client state need to recover, do it. */
+		if (clp->cl_state)
+			nfs4_schedule_state_manager(clp);
+	}
+out:
+	return status;
+}
+
+struct rpc_cred *nfs4_get_machine_cred_locked(struct nfs_client *clp)
+{
+	struct rpc_cred *cred = NULL;
+
+	if (clp->cl_machine_cred != NULL)
+		cred = get_rpccred(clp->cl_machine_cred);
+	return cred;
+}
+
+static void nfs4_root_machine_cred(struct nfs_client *clp)
+{
+	struct rpc_cred *cred, *new;
+
+	new = rpc_lookup_machine_cred(NULL);
+	spin_lock(&clp->cl_lock);
+	cred = clp->cl_machine_cred;
+	clp->cl_machine_cred = new;
+	spin_unlock(&clp->cl_lock);
+	if (cred != NULL)
+		put_rpccred(cred);
+}
+
+static struct rpc_cred *
+nfs4_get_renew_cred_server_locked(struct nfs_server *server)
+{
+	struct rpc_cred *cred = NULL;
+	struct nfs4_state_owner *sp;
+	struct rb_node *pos;
+
+	for (pos = rb_first(&server->state_owners);
+	     pos != NULL;
+	     pos = rb_next(pos)) {
+		sp = rb_entry(pos, struct nfs4_state_owner, so_server_node);
+		if (list_empty(&sp->so_states))
+			continue;
+		cred = get_rpccred(sp->so_cred);
+		break;
+	}
+	return cred;
+}
+
+/**
+ * nfs4_get_renew_cred_locked - Acquire credential for a renew operation
+ * @clp: client state handle
+ *
+ * Returns an rpc_cred with reference count bumped, or NULL.
+ * Caller must hold clp->cl_lock.
+ */
+struct rpc_cred *nfs4_get_renew_cred_locked(struct nfs_client *clp)
+{
+	struct rpc_cred *cred = NULL;
+	struct nfs_server *server;
+
+	/* Use machine credentials if available */
+	cred = nfs4_get_machine_cred_locked(clp);
+	if (cred != NULL)
+		goto out;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		cred = nfs4_get_renew_cred_server_locked(server);
+		if (cred != NULL)
+			break;
+	}
+	rcu_read_unlock();
+
+out:
+	return cred;
+}
+
+static void nfs4_end_drain_slot_table(struct nfs4_slot_table *tbl)
+{
+	if (test_and_clear_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state)) {
+		spin_lock(&tbl->slot_tbl_lock);
+		nfs41_wake_slot_table(tbl);
+		spin_unlock(&tbl->slot_tbl_lock);
+	}
+}
+
+static void nfs4_end_drain_session(struct nfs_client *clp)
+{
+	struct nfs4_session *ses = clp->cl_session;
+
+	if (clp->cl_slot_tbl) {
+		nfs4_end_drain_slot_table(clp->cl_slot_tbl);
+		return;
+	}
+
+	if (ses != NULL) {
+		nfs4_end_drain_slot_table(&ses->bc_slot_table);
+		nfs4_end_drain_slot_table(&ses->fc_slot_table);
+	}
+}
+
+static int nfs4_drain_slot_tbl(struct nfs4_slot_table *tbl)
+{
+	set_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state);
+	spin_lock(&tbl->slot_tbl_lock);
+	if (tbl->highest_used_slotid != NFS4_NO_SLOT) {
+		reinit_completion(&tbl->complete);
+		spin_unlock(&tbl->slot_tbl_lock);
+		return wait_for_completion_interruptible(&tbl->complete);
+	}
+	spin_unlock(&tbl->slot_tbl_lock);
+	return 0;
+}
+
+static int nfs4_begin_drain_session(struct nfs_client *clp)
+{
+	struct nfs4_session *ses = clp->cl_session;
+	int ret;
+
+	if (clp->cl_slot_tbl)
+		return nfs4_drain_slot_tbl(clp->cl_slot_tbl);
+
+	/* back channel */
+	ret = nfs4_drain_slot_tbl(&ses->bc_slot_table);
+	if (ret)
+		return ret;
+	/* fore channel */
+	return nfs4_drain_slot_tbl(&ses->fc_slot_table);
+}
+
+#if defined(CONFIG_NFS_V4_1)
+
+static int nfs41_setup_state_renewal(struct nfs_client *clp)
+{
+	int status;
+	struct nfs_fsinfo fsinfo;
+	unsigned long now;
+
+	if (!test_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state)) {
+		nfs4_schedule_state_renewal(clp);
+		return 0;
+	}
+
+	now = jiffies;
+	status = nfs4_proc_get_lease_time(clp, &fsinfo);
+	if (status == 0) {
+		nfs4_set_lease_period(clp, fsinfo.lease_time * HZ, now);
+		nfs4_schedule_state_renewal(clp);
+	}
+
+	return status;
+}
+
+static void nfs41_finish_session_reset(struct nfs_client *clp)
+{
+	clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+	clear_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
+	/* create_session negotiated new slot table */
+	clear_bit(NFS4CLNT_BIND_CONN_TO_SESSION, &clp->cl_state);
+	nfs41_setup_state_renewal(clp);
+}
+
+int nfs41_init_clientid(struct nfs_client *clp, struct rpc_cred *cred)
+{
+	int status;
+
+	if (test_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state))
+		goto do_confirm;
+	status = nfs4_proc_exchange_id(clp, cred);
+	if (status != 0)
+		goto out;
+	set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+do_confirm:
+	status = nfs4_proc_create_session(clp, cred);
+	if (status != 0)
+		goto out;
+	nfs41_finish_session_reset(clp);
+	nfs_mark_client_ready(clp, NFS_CS_READY);
+out:
+	return status;
+}
+
+/**
+ * nfs41_discover_server_trunking - Detect server IP address trunking (mv1)
+ *
+ * @clp: nfs_client under test
+ * @result: OUT: found nfs_client, or clp
+ * @cred: credential to use for trunking test
+ *
+ * Returns NFS4_OK, a negative errno, or a negative NFS4ERR status.
+ * If NFS4_OK is returned, an nfs_client pointer is planted in
+ * "result".
+ *
+ * Note: The returned client may not yet be marked ready.
+ */
+int nfs41_discover_server_trunking(struct nfs_client *clp,
+				   struct nfs_client **result,
+				   struct rpc_cred *cred)
+{
+	int status;
+
+	status = nfs4_proc_exchange_id(clp, cred);
+	if (status != NFS4_OK)
+		return status;
+
+	status = nfs41_walk_client_list(clp, result, cred);
+	if (status < 0)
+		return status;
+	if (clp != *result)
+		return 0;
+
+	/*
+	 * Purge state if the client id was established in a prior
+	 * instance and the client id could not have arrived on the
+	 * server via Transparent State Migration.
+	 */
+	if (clp->cl_exchange_flags & EXCHGID4_FLAG_CONFIRMED_R) {
+		if (!test_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags))
+			set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
+		else
+			set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+	}
+	nfs4_schedule_state_manager(clp);
+	status = nfs_wait_client_init_complete(clp);
+	if (status < 0)
+		nfs_put_client(clp);
+	return status;
+}
+
+#endif /* CONFIG_NFS_V4_1 */
+
+/**
+ * nfs4_get_clid_cred - Acquire credential for a setclientid operation
+ * @clp: client state handle
+ *
+ * Returns an rpc_cred with reference count bumped, or NULL.
+ */
+struct rpc_cred *nfs4_get_clid_cred(struct nfs_client *clp)
+{
+	struct rpc_cred *cred;
+
+	spin_lock(&clp->cl_lock);
+	cred = nfs4_get_machine_cred_locked(clp);
+	spin_unlock(&clp->cl_lock);
+	return cred;
+}
+
+static struct nfs4_state_owner *
+nfs4_find_state_owner_locked(struct nfs_server *server, struct rpc_cred *cred)
+{
+	struct rb_node **p = &server->state_owners.rb_node,
+		       *parent = NULL;
+	struct nfs4_state_owner *sp;
+
+	while (*p != NULL) {
+		parent = *p;
+		sp = rb_entry(parent, struct nfs4_state_owner, so_server_node);
+
+		if (cred < sp->so_cred)
+			p = &parent->rb_left;
+		else if (cred > sp->so_cred)
+			p = &parent->rb_right;
+		else {
+			if (!list_empty(&sp->so_lru))
+				list_del_init(&sp->so_lru);
+			atomic_inc(&sp->so_count);
+			return sp;
+		}
+	}
+	return NULL;
+}
+
+static struct nfs4_state_owner *
+nfs4_insert_state_owner_locked(struct nfs4_state_owner *new)
+{
+	struct nfs_server *server = new->so_server;
+	struct rb_node **p = &server->state_owners.rb_node,
+		       *parent = NULL;
+	struct nfs4_state_owner *sp;
+
+	while (*p != NULL) {
+		parent = *p;
+		sp = rb_entry(parent, struct nfs4_state_owner, so_server_node);
+
+		if (new->so_cred < sp->so_cred)
+			p = &parent->rb_left;
+		else if (new->so_cred > sp->so_cred)
+			p = &parent->rb_right;
+		else {
+			if (!list_empty(&sp->so_lru))
+				list_del_init(&sp->so_lru);
+			atomic_inc(&sp->so_count);
+			return sp;
+		}
+	}
+	rb_link_node(&new->so_server_node, parent, p);
+	rb_insert_color(&new->so_server_node, &server->state_owners);
+	return new;
+}
+
+static void
+nfs4_remove_state_owner_locked(struct nfs4_state_owner *sp)
+{
+	struct nfs_server *server = sp->so_server;
+
+	if (!RB_EMPTY_NODE(&sp->so_server_node))
+		rb_erase(&sp->so_server_node, &server->state_owners);
+}
+
+static void
+nfs4_init_seqid_counter(struct nfs_seqid_counter *sc)
+{
+	sc->create_time = ktime_get();
+	sc->flags = 0;
+	sc->counter = 0;
+	spin_lock_init(&sc->lock);
+	INIT_LIST_HEAD(&sc->list);
+	rpc_init_wait_queue(&sc->wait, "Seqid_waitqueue");
+}
+
+static void
+nfs4_destroy_seqid_counter(struct nfs_seqid_counter *sc)
+{
+	rpc_destroy_wait_queue(&sc->wait);
+}
+
+/*
+ * nfs4_alloc_state_owner(): this is called on the OPEN or CREATE path to
+ * create a new state_owner.
+ *
+ */
+static struct nfs4_state_owner *
+nfs4_alloc_state_owner(struct nfs_server *server,
+		struct rpc_cred *cred,
+		gfp_t gfp_flags)
+{
+	struct nfs4_state_owner *sp;
+
+	sp = kzalloc(sizeof(*sp), gfp_flags);
+	if (!sp)
+		return NULL;
+	sp->so_seqid.owner_id = ida_simple_get(&server->openowner_id, 0, 0,
+						gfp_flags);
+	if (sp->so_seqid.owner_id < 0) {
+		kfree(sp);
+		return NULL;
+	}
+	sp->so_server = server;
+	sp->so_cred = get_rpccred(cred);
+	spin_lock_init(&sp->so_lock);
+	INIT_LIST_HEAD(&sp->so_states);
+	nfs4_init_seqid_counter(&sp->so_seqid);
+	atomic_set(&sp->so_count, 1);
+	INIT_LIST_HEAD(&sp->so_lru);
+	seqcount_init(&sp->so_reclaim_seqcount);
+	mutex_init(&sp->so_delegreturn_mutex);
+	return sp;
+}
+
+static void
+nfs4_reset_state_owner(struct nfs4_state_owner *sp)
+{
+	/* This state_owner is no longer usable, but must
+	 * remain in place so that state recovery can find it
+	 * and the opens associated with it.
+	 * It may also be used for new 'open' request to
+	 * return a delegation to the server.
+	 * So update the 'create_time' so that it looks like
+	 * a new state_owner.  This will cause the server to
+	 * request an OPEN_CONFIRM to start a new sequence.
+	 */
+	sp->so_seqid.create_time = ktime_get();
+}
+
+static void nfs4_free_state_owner(struct nfs4_state_owner *sp)
+{
+	nfs4_destroy_seqid_counter(&sp->so_seqid);
+	put_rpccred(sp->so_cred);
+	ida_simple_remove(&sp->so_server->openowner_id, sp->so_seqid.owner_id);
+	kfree(sp);
+}
+
+static void nfs4_gc_state_owners(struct nfs_server *server)
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_state_owner *sp, *tmp;
+	unsigned long time_min, time_max;
+	LIST_HEAD(doomed);
+
+	spin_lock(&clp->cl_lock);
+	time_max = jiffies;
+	time_min = (long)time_max - (long)clp->cl_lease_time;
+	list_for_each_entry_safe(sp, tmp, &server->state_owners_lru, so_lru) {
+		/* NB: LRU is sorted so that oldest is at the head */
+		if (time_in_range(sp->so_expires, time_min, time_max))
+			break;
+		list_move(&sp->so_lru, &doomed);
+		nfs4_remove_state_owner_locked(sp);
+	}
+	spin_unlock(&clp->cl_lock);
+
+	list_for_each_entry_safe(sp, tmp, &doomed, so_lru) {
+		list_del(&sp->so_lru);
+		nfs4_free_state_owner(sp);
+	}
+}
+
+/**
+ * nfs4_get_state_owner - Look up a state owner given a credential
+ * @server: nfs_server to search
+ * @cred: RPC credential to match
+ *
+ * Returns a pointer to an instantiated nfs4_state_owner struct, or NULL.
+ */
+struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *server,
+					      struct rpc_cred *cred,
+					      gfp_t gfp_flags)
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_state_owner *sp, *new;
+
+	spin_lock(&clp->cl_lock);
+	sp = nfs4_find_state_owner_locked(server, cred);
+	spin_unlock(&clp->cl_lock);
+	if (sp != NULL)
+		goto out;
+	new = nfs4_alloc_state_owner(server, cred, gfp_flags);
+	if (new == NULL)
+		goto out;
+	spin_lock(&clp->cl_lock);
+	sp = nfs4_insert_state_owner_locked(new);
+	spin_unlock(&clp->cl_lock);
+	if (sp != new)
+		nfs4_free_state_owner(new);
+out:
+	nfs4_gc_state_owners(server);
+	return sp;
+}
+
+/**
+ * nfs4_put_state_owner - Release a nfs4_state_owner
+ * @sp: state owner data to release
+ *
+ * Note that we keep released state owners on an LRU
+ * list.
+ * This caches valid state owners so that they can be
+ * reused, to avoid the OPEN_CONFIRM on minor version 0.
+ * It also pins the uniquifier of dropped state owners for
+ * a while, to ensure that those state owner names are
+ * never reused.
+ */
+void nfs4_put_state_owner(struct nfs4_state_owner *sp)
+{
+	struct nfs_server *server = sp->so_server;
+	struct nfs_client *clp = server->nfs_client;
+
+	if (!atomic_dec_and_lock(&sp->so_count, &clp->cl_lock))
+		return;
+
+	sp->so_expires = jiffies;
+	list_add_tail(&sp->so_lru, &server->state_owners_lru);
+	spin_unlock(&clp->cl_lock);
+}
+
+/**
+ * nfs4_purge_state_owners - Release all cached state owners
+ * @server: nfs_server with cached state owners to release
+ * @head: resulting list of state owners
+ *
+ * Called at umount time.  Remaining state owners will be on
+ * the LRU with ref count of zero.
+ * Note that the state owners are not freed, but are added
+ * to the list @head, which can later be used as an argument
+ * to nfs4_free_state_owners.
+ */
+void nfs4_purge_state_owners(struct nfs_server *server, struct list_head *head)
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_state_owner *sp, *tmp;
+
+	spin_lock(&clp->cl_lock);
+	list_for_each_entry_safe(sp, tmp, &server->state_owners_lru, so_lru) {
+		list_move(&sp->so_lru, head);
+		nfs4_remove_state_owner_locked(sp);
+	}
+	spin_unlock(&clp->cl_lock);
+}
+
+/**
+ * nfs4_purge_state_owners - Release all cached state owners
+ * @head: resulting list of state owners
+ *
+ * Frees a list of state owners that was generated by
+ * nfs4_purge_state_owners
+ */
+void nfs4_free_state_owners(struct list_head *head)
+{
+	struct nfs4_state_owner *sp, *tmp;
+
+	list_for_each_entry_safe(sp, tmp, head, so_lru) {
+		list_del(&sp->so_lru);
+		nfs4_free_state_owner(sp);
+	}
+}
+
+static struct nfs4_state *
+nfs4_alloc_open_state(void)
+{
+	struct nfs4_state *state;
+
+	state = kzalloc(sizeof(*state), GFP_NOFS);
+	if (!state)
+		return NULL;
+	atomic_set(&state->count, 1);
+	INIT_LIST_HEAD(&state->lock_states);
+	spin_lock_init(&state->state_lock);
+	seqlock_init(&state->seqlock);
+	init_waitqueue_head(&state->waitq);
+	return state;
+}
+
+void
+nfs4_state_set_mode_locked(struct nfs4_state *state, fmode_t fmode)
+{
+	if (state->state == fmode)
+		return;
+	/* NB! List reordering - see the reclaim code for why.  */
+	if ((fmode & FMODE_WRITE) != (state->state & FMODE_WRITE)) {
+		if (fmode & FMODE_WRITE)
+			list_move(&state->open_states, &state->owner->so_states);
+		else
+			list_move_tail(&state->open_states, &state->owner->so_states);
+	}
+	state->state = fmode;
+}
+
+static struct nfs4_state *
+__nfs4_find_state_byowner(struct inode *inode, struct nfs4_state_owner *owner)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs4_state *state;
+
+	list_for_each_entry(state, &nfsi->open_states, inode_states) {
+		if (state->owner != owner)
+			continue;
+		if (!nfs4_valid_open_stateid(state))
+			continue;
+		if (atomic_inc_not_zero(&state->count))
+			return state;
+	}
+	return NULL;
+}
+
+static void
+nfs4_free_open_state(struct nfs4_state *state)
+{
+	kfree(state);
+}
+
+struct nfs4_state *
+nfs4_get_open_state(struct inode *inode, struct nfs4_state_owner *owner)
+{
+	struct nfs4_state *state, *new;
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	spin_lock(&inode->i_lock);
+	state = __nfs4_find_state_byowner(inode, owner);
+	spin_unlock(&inode->i_lock);
+	if (state)
+		goto out;
+	new = nfs4_alloc_open_state();
+	spin_lock(&owner->so_lock);
+	spin_lock(&inode->i_lock);
+	state = __nfs4_find_state_byowner(inode, owner);
+	if (state == NULL && new != NULL) {
+		state = new;
+		state->owner = owner;
+		atomic_inc(&owner->so_count);
+		list_add(&state->inode_states, &nfsi->open_states);
+		ihold(inode);
+		state->inode = inode;
+		spin_unlock(&inode->i_lock);
+		/* Note: The reclaim code dictates that we add stateless
+		 * and read-only stateids to the end of the list */
+		list_add_tail(&state->open_states, &owner->so_states);
+		spin_unlock(&owner->so_lock);
+	} else {
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&owner->so_lock);
+		if (new)
+			nfs4_free_open_state(new);
+	}
+out:
+	return state;
+}
+
+void nfs4_put_open_state(struct nfs4_state *state)
+{
+	struct inode *inode = state->inode;
+	struct nfs4_state_owner *owner = state->owner;
+
+	if (!atomic_dec_and_lock(&state->count, &owner->so_lock))
+		return;
+	spin_lock(&inode->i_lock);
+	list_del(&state->inode_states);
+	list_del(&state->open_states);
+	spin_unlock(&inode->i_lock);
+	spin_unlock(&owner->so_lock);
+	iput(inode);
+	nfs4_free_open_state(state);
+	nfs4_put_state_owner(owner);
+}
+
+/*
+ * Close the current file.
+ */
+static void __nfs4_close(struct nfs4_state *state,
+		fmode_t fmode, gfp_t gfp_mask, int wait)
+{
+	struct nfs4_state_owner *owner = state->owner;
+	int call_close = 0;
+	fmode_t newstate;
+
+	atomic_inc(&owner->so_count);
+	/* Protect against nfs4_find_state() */
+	spin_lock(&owner->so_lock);
+	switch (fmode & (FMODE_READ | FMODE_WRITE)) {
+		case FMODE_READ:
+			state->n_rdonly--;
+			break;
+		case FMODE_WRITE:
+			state->n_wronly--;
+			break;
+		case FMODE_READ|FMODE_WRITE:
+			state->n_rdwr--;
+	}
+	newstate = FMODE_READ|FMODE_WRITE;
+	if (state->n_rdwr == 0) {
+		if (state->n_rdonly == 0) {
+			newstate &= ~FMODE_READ;
+			call_close |= test_bit(NFS_O_RDONLY_STATE, &state->flags);
+			call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
+		}
+		if (state->n_wronly == 0) {
+			newstate &= ~FMODE_WRITE;
+			call_close |= test_bit(NFS_O_WRONLY_STATE, &state->flags);
+			call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
+		}
+		if (newstate == 0)
+			clear_bit(NFS_DELEGATED_STATE, &state->flags);
+	}
+	nfs4_state_set_mode_locked(state, newstate);
+	spin_unlock(&owner->so_lock);
+
+	if (!call_close) {
+		nfs4_put_open_state(state);
+		nfs4_put_state_owner(owner);
+	} else
+		nfs4_do_close(state, gfp_mask, wait);
+}
+
+void nfs4_close_state(struct nfs4_state *state, fmode_t fmode)
+{
+	__nfs4_close(state, fmode, GFP_NOFS, 0);
+}
+
+void nfs4_close_sync(struct nfs4_state *state, fmode_t fmode)
+{
+	__nfs4_close(state, fmode, GFP_KERNEL, 1);
+}
+
+/*
+ * Search the state->lock_states for an existing lock_owner
+ * that is compatible with either of the given owners.
+ * If the second is non-zero, then the first refers to a Posix-lock
+ * owner (current->files) and the second refers to a flock/OFD
+ * owner (struct file*).  In that case, prefer a match for the first
+ * owner.
+ * If both sorts of locks are held on the one file we cannot know
+ * which stateid was intended to be used, so a "correct" choice cannot
+ * be made.  Failing that, a "consistent" choice is preferable.  The
+ * consistent choice we make is to prefer the first owner, that of a
+ * Posix lock.
+ */
+static struct nfs4_lock_state *
+__nfs4_find_lock_state(struct nfs4_state *state,
+		       fl_owner_t fl_owner, fl_owner_t fl_owner2)
+{
+	struct nfs4_lock_state *pos, *ret = NULL;
+	list_for_each_entry(pos, &state->lock_states, ls_locks) {
+		if (pos->ls_owner == fl_owner) {
+			ret = pos;
+			break;
+		}
+		if (pos->ls_owner == fl_owner2)
+			ret = pos;
+	}
+	if (ret)
+		refcount_inc(&ret->ls_count);
+	return ret;
+}
+
+/*
+ * Return a compatible lock_state. If no initialized lock_state structure
+ * exists, return an uninitialized one.
+ *
+ */
+static struct nfs4_lock_state *nfs4_alloc_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)
+{
+	struct nfs4_lock_state *lsp;
+	struct nfs_server *server = state->owner->so_server;
+
+	lsp = kzalloc(sizeof(*lsp), GFP_NOFS);
+	if (lsp == NULL)
+		return NULL;
+	nfs4_init_seqid_counter(&lsp->ls_seqid);
+	refcount_set(&lsp->ls_count, 1);
+	lsp->ls_state = state;
+	lsp->ls_owner = fl_owner;
+	lsp->ls_seqid.owner_id = ida_simple_get(&server->lockowner_id, 0, 0, GFP_NOFS);
+	if (lsp->ls_seqid.owner_id < 0)
+		goto out_free;
+	INIT_LIST_HEAD(&lsp->ls_locks);
+	return lsp;
+out_free:
+	kfree(lsp);
+	return NULL;
+}
+
+void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp)
+{
+	ida_simple_remove(&server->lockowner_id, lsp->ls_seqid.owner_id);
+	nfs4_destroy_seqid_counter(&lsp->ls_seqid);
+	kfree(lsp);
+}
+
+/*
+ * Return a compatible lock_state. If no initialized lock_state structure
+ * exists, return an uninitialized one.
+ *
+ */
+static struct nfs4_lock_state *nfs4_get_lock_state(struct nfs4_state *state, fl_owner_t owner)
+{
+	struct nfs4_lock_state *lsp, *new = NULL;
+	
+	for(;;) {
+		spin_lock(&state->state_lock);
+		lsp = __nfs4_find_lock_state(state, owner, NULL);
+		if (lsp != NULL)
+			break;
+		if (new != NULL) {
+			list_add(&new->ls_locks, &state->lock_states);
+			set_bit(LK_STATE_IN_USE, &state->flags);
+			lsp = new;
+			new = NULL;
+			break;
+		}
+		spin_unlock(&state->state_lock);
+		new = nfs4_alloc_lock_state(state, owner);
+		if (new == NULL)
+			return NULL;
+	}
+	spin_unlock(&state->state_lock);
+	if (new != NULL)
+		nfs4_free_lock_state(state->owner->so_server, new);
+	return lsp;
+}
+
+/*
+ * Release reference to lock_state, and free it if we see that
+ * it is no longer in use
+ */
+void nfs4_put_lock_state(struct nfs4_lock_state *lsp)
+{
+	struct nfs_server *server;
+	struct nfs4_state *state;
+
+	if (lsp == NULL)
+		return;
+	state = lsp->ls_state;
+	if (!refcount_dec_and_lock(&lsp->ls_count, &state->state_lock))
+		return;
+	list_del(&lsp->ls_locks);
+	if (list_empty(&state->lock_states))
+		clear_bit(LK_STATE_IN_USE, &state->flags);
+	spin_unlock(&state->state_lock);
+	server = state->owner->so_server;
+	if (test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags)) {
+		struct nfs_client *clp = server->nfs_client;
+
+		clp->cl_mvops->free_lock_state(server, lsp);
+	} else
+		nfs4_free_lock_state(server, lsp);
+}
+
+static void nfs4_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
+{
+	struct nfs4_lock_state *lsp = src->fl_u.nfs4_fl.owner;
+
+	dst->fl_u.nfs4_fl.owner = lsp;
+	refcount_inc(&lsp->ls_count);
+}
+
+static void nfs4_fl_release_lock(struct file_lock *fl)
+{
+	nfs4_put_lock_state(fl->fl_u.nfs4_fl.owner);
+}
+
+static const struct file_lock_operations nfs4_fl_lock_ops = {
+	.fl_copy_lock = nfs4_fl_copy_lock,
+	.fl_release_private = nfs4_fl_release_lock,
+};
+
+int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl)
+{
+	struct nfs4_lock_state *lsp;
+
+	if (fl->fl_ops != NULL)
+		return 0;
+	lsp = nfs4_get_lock_state(state, fl->fl_owner);
+	if (lsp == NULL)
+		return -ENOMEM;
+	fl->fl_u.nfs4_fl.owner = lsp;
+	fl->fl_ops = &nfs4_fl_lock_ops;
+	return 0;
+}
+
+static int nfs4_copy_lock_stateid(nfs4_stateid *dst,
+		struct nfs4_state *state,
+		const struct nfs_lock_context *l_ctx)
+{
+	struct nfs4_lock_state *lsp;
+	fl_owner_t fl_owner, fl_flock_owner;
+	int ret = -ENOENT;
+
+	if (l_ctx == NULL)
+		goto out;
+
+	if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)
+		goto out;
+
+	fl_owner = l_ctx->lockowner;
+	fl_flock_owner = l_ctx->open_context->flock_owner;
+
+	spin_lock(&state->state_lock);
+	lsp = __nfs4_find_lock_state(state, fl_owner, fl_flock_owner);
+	if (lsp && test_bit(NFS_LOCK_LOST, &lsp->ls_flags))
+		ret = -EIO;
+	else if (lsp != NULL && test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags) != 0) {
+		nfs4_stateid_copy(dst, &lsp->ls_stateid);
+		ret = 0;
+	}
+	spin_unlock(&state->state_lock);
+	nfs4_put_lock_state(lsp);
+out:
+	return ret;
+}
+
+bool nfs4_refresh_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)
+{
+	bool ret;
+	int seq;
+
+	do {
+		ret = false;
+		seq = read_seqbegin(&state->seqlock);
+		if (nfs4_state_match_open_stateid_other(state, dst)) {
+			dst->seqid = state->open_stateid.seqid;
+			ret = true;
+		}
+	} while (read_seqretry(&state->seqlock, seq));
+	return ret;
+}
+
+bool nfs4_copy_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)
+{
+	bool ret;
+	const nfs4_stateid *src;
+	int seq;
+
+	do {
+		ret = false;
+		src = &zero_stateid;
+		seq = read_seqbegin(&state->seqlock);
+		if (test_bit(NFS_OPEN_STATE, &state->flags)) {
+			src = &state->open_stateid;
+			ret = true;
+		}
+		nfs4_stateid_copy(dst, src);
+	} while (read_seqretry(&state->seqlock, seq));
+	return ret;
+}
+
+/*
+ * Byte-range lock aware utility to initialize the stateid of read/write
+ * requests.
+ */
+int nfs4_select_rw_stateid(struct nfs4_state *state,
+		fmode_t fmode, const struct nfs_lock_context *l_ctx,
+		nfs4_stateid *dst, struct rpc_cred **cred)
+{
+	int ret;
+
+	if (!nfs4_valid_open_stateid(state))
+		return -EIO;
+	if (cred != NULL)
+		*cred = NULL;
+	ret = nfs4_copy_lock_stateid(dst, state, l_ctx);
+	if (ret == -EIO)
+		/* A lost lock - don't even consider delegations */
+		goto out;
+	/* returns true if delegation stateid found and copied */
+	if (nfs4_copy_delegation_stateid(state->inode, fmode, dst, cred)) {
+		ret = 0;
+		goto out;
+	}
+	if (ret != -ENOENT)
+		/* nfs4_copy_delegation_stateid() didn't over-write
+		 * dst, so it still has the lock stateid which we now
+		 * choose to use.
+		 */
+		goto out;
+	nfs4_copy_open_stateid(dst, state);
+	ret = 0;
+out:
+	if (nfs_server_capable(state->inode, NFS_CAP_STATEID_NFSV41))
+		dst->seqid = 0;
+	return ret;
+}
+
+struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask)
+{
+	struct nfs_seqid *new;
+
+	new = kmalloc(sizeof(*new), gfp_mask);
+	if (new == NULL)
+		return ERR_PTR(-ENOMEM);
+	new->sequence = counter;
+	INIT_LIST_HEAD(&new->list);
+	new->task = NULL;
+	return new;
+}
+
+void nfs_release_seqid(struct nfs_seqid *seqid)
+{
+	struct nfs_seqid_counter *sequence;
+
+	if (seqid == NULL || list_empty(&seqid->list))
+		return;
+	sequence = seqid->sequence;
+	spin_lock(&sequence->lock);
+	list_del_init(&seqid->list);
+	if (!list_empty(&sequence->list)) {
+		struct nfs_seqid *next;
+
+		next = list_first_entry(&sequence->list,
+				struct nfs_seqid, list);
+		rpc_wake_up_queued_task(&sequence->wait, next->task);
+	}
+	spin_unlock(&sequence->lock);
+}
+
+void nfs_free_seqid(struct nfs_seqid *seqid)
+{
+	nfs_release_seqid(seqid);
+	kfree(seqid);
+}
+
+/*
+ * Increment the seqid if the OPEN/OPEN_DOWNGRADE/CLOSE succeeded, or
+ * failed with a seqid incrementing error -
+ * see comments nfs4.h:seqid_mutating_error()
+ */
+static void nfs_increment_seqid(int status, struct nfs_seqid *seqid)
+{
+	switch (status) {
+		case 0:
+			break;
+		case -NFS4ERR_BAD_SEQID:
+			if (seqid->sequence->flags & NFS_SEQID_CONFIRMED)
+				return;
+			pr_warn_ratelimited("NFS: v4 server returned a bad"
+					" sequence-id error on an"
+					" unconfirmed sequence %p!\n",
+					seqid->sequence);
+		case -NFS4ERR_STALE_CLIENTID:
+		case -NFS4ERR_STALE_STATEID:
+		case -NFS4ERR_BAD_STATEID:
+		case -NFS4ERR_BADXDR:
+		case -NFS4ERR_RESOURCE:
+		case -NFS4ERR_NOFILEHANDLE:
+		case -NFS4ERR_MOVED:
+			/* Non-seqid mutating errors */
+			return;
+	};
+	/*
+	 * Note: no locking needed as we are guaranteed to be first
+	 * on the sequence list
+	 */
+	seqid->sequence->counter++;
+}
+
+void nfs_increment_open_seqid(int status, struct nfs_seqid *seqid)
+{
+	struct nfs4_state_owner *sp;
+
+	if (seqid == NULL)
+		return;
+
+	sp = container_of(seqid->sequence, struct nfs4_state_owner, so_seqid);
+	if (status == -NFS4ERR_BAD_SEQID)
+		nfs4_reset_state_owner(sp);
+	if (!nfs4_has_session(sp->so_server->nfs_client))
+		nfs_increment_seqid(status, seqid);
+}
+
+/*
+ * Increment the seqid if the LOCK/LOCKU succeeded, or
+ * failed with a seqid incrementing error -
+ * see comments nfs4.h:seqid_mutating_error()
+ */
+void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid)
+{
+	if (seqid != NULL)
+		nfs_increment_seqid(status, seqid);
+}
+
+int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task)
+{
+	struct nfs_seqid_counter *sequence;
+	int status = 0;
+
+	if (seqid == NULL)
+		goto out;
+	sequence = seqid->sequence;
+	spin_lock(&sequence->lock);
+	seqid->task = task;
+	if (list_empty(&seqid->list))
+		list_add_tail(&seqid->list, &sequence->list);
+	if (list_first_entry(&sequence->list, struct nfs_seqid, list) == seqid)
+		goto unlock;
+	rpc_sleep_on(&sequence->wait, task, NULL);
+	status = -EAGAIN;
+unlock:
+	spin_unlock(&sequence->lock);
+out:
+	return status;
+}
+
+static int nfs4_run_state_manager(void *);
+
+static void nfs4_clear_state_manager_bit(struct nfs_client *clp)
+{
+	smp_mb__before_atomic();
+	clear_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);
+	smp_mb__after_atomic();
+	wake_up_bit(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING);
+	rpc_wake_up(&clp->cl_rpcwaitq);
+}
+
+/*
+ * Schedule the nfs_client asynchronous state management routine
+ */
+void nfs4_schedule_state_manager(struct nfs_client *clp)
+{
+	struct task_struct *task;
+	char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
+
+	set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
+	if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
+		return;
+	__module_get(THIS_MODULE);
+	refcount_inc(&clp->cl_count);
+
+	/* The rcu_read_lock() is not strictly necessary, as the state
+	 * manager is the only thread that ever changes the rpc_xprt
+	 * after it's initialized.  At this point, we're single threaded. */
+	rcu_read_lock();
+	snprintf(buf, sizeof(buf), "%s-manager",
+			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+	rcu_read_unlock();
+	task = kthread_run(nfs4_run_state_manager, clp, "%s", buf);
+	if (IS_ERR(task)) {
+		printk(KERN_ERR "%s: kthread_run: %ld\n",
+			__func__, PTR_ERR(task));
+		nfs4_clear_state_manager_bit(clp);
+		nfs_put_client(clp);
+		module_put(THIS_MODULE);
+	}
+}
+
+/*
+ * Schedule a lease recovery attempt
+ */
+void nfs4_schedule_lease_recovery(struct nfs_client *clp)
+{
+	if (!clp)
+		return;
+	if (!test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state))
+		set_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state);
+	dprintk("%s: scheduling lease recovery for server %s\n", __func__,
+			clp->cl_hostname);
+	nfs4_schedule_state_manager(clp);
+}
+EXPORT_SYMBOL_GPL(nfs4_schedule_lease_recovery);
+
+/**
+ * nfs4_schedule_migration_recovery - trigger migration recovery
+ *
+ * @server: FSID that is migrating
+ *
+ * Returns zero if recovery has started, otherwise a negative NFS4ERR
+ * value is returned.
+ */
+int nfs4_schedule_migration_recovery(const struct nfs_server *server)
+{
+	struct nfs_client *clp = server->nfs_client;
+
+	if (server->fh_expire_type != NFS4_FH_PERSISTENT) {
+		pr_err("NFS: volatile file handles not supported (server %s)\n",
+				clp->cl_hostname);
+		return -NFS4ERR_IO;
+	}
+
+	if (test_bit(NFS_MIG_FAILED, &server->mig_status))
+		return -NFS4ERR_IO;
+
+	dprintk("%s: scheduling migration recovery for (%llx:%llx) on %s\n",
+			__func__,
+			(unsigned long long)server->fsid.major,
+			(unsigned long long)server->fsid.minor,
+			clp->cl_hostname);
+
+	set_bit(NFS_MIG_IN_TRANSITION,
+			&((struct nfs_server *)server)->mig_status);
+	set_bit(NFS4CLNT_MOVED, &clp->cl_state);
+
+	nfs4_schedule_state_manager(clp);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs4_schedule_migration_recovery);
+
+/**
+ * nfs4_schedule_lease_moved_recovery - start lease-moved recovery
+ *
+ * @clp: server to check for moved leases
+ *
+ */
+void nfs4_schedule_lease_moved_recovery(struct nfs_client *clp)
+{
+	dprintk("%s: scheduling lease-moved recovery for client ID %llx on %s\n",
+		__func__, clp->cl_clientid, clp->cl_hostname);
+
+	set_bit(NFS4CLNT_LEASE_MOVED, &clp->cl_state);
+	nfs4_schedule_state_manager(clp);
+}
+EXPORT_SYMBOL_GPL(nfs4_schedule_lease_moved_recovery);
+
+int nfs4_wait_clnt_recover(struct nfs_client *clp)
+{
+	int res;
+
+	might_sleep();
+
+	refcount_inc(&clp->cl_count);
+	res = wait_on_bit_action(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING,
+				 nfs_wait_bit_killable, TASK_KILLABLE);
+	if (res)
+		goto out;
+	if (clp->cl_cons_state < 0)
+		res = clp->cl_cons_state;
+out:
+	nfs_put_client(clp);
+	return res;
+}
+
+int nfs4_client_recover_expired_lease(struct nfs_client *clp)
+{
+	unsigned int loop;
+	int ret;
+
+	for (loop = NFS4_MAX_LOOP_ON_RECOVER; loop != 0; loop--) {
+		ret = nfs4_wait_clnt_recover(clp);
+		if (ret != 0)
+			break;
+		if (!test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) &&
+		    !test_bit(NFS4CLNT_CHECK_LEASE,&clp->cl_state))
+			break;
+		nfs4_schedule_state_manager(clp);
+		ret = -EIO;
+	}
+	return ret;
+}
+
+/*
+ * nfs40_handle_cb_pathdown - return all delegations after NFS4ERR_CB_PATH_DOWN
+ * @clp: client to process
+ *
+ * Set the NFS4CLNT_LEASE_EXPIRED state in order to force a
+ * resend of the SETCLIENTID and hence re-establish the
+ * callback channel. Then return all existing delegations.
+ */
+static void nfs40_handle_cb_pathdown(struct nfs_client *clp)
+{
+	set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
+	nfs_expire_all_delegations(clp);
+	dprintk("%s: handling CB_PATHDOWN recovery for server %s\n", __func__,
+			clp->cl_hostname);
+}
+
+void nfs4_schedule_path_down_recovery(struct nfs_client *clp)
+{
+	nfs40_handle_cb_pathdown(clp);
+	nfs4_schedule_state_manager(clp);
+}
+
+static int nfs4_state_mark_reclaim_reboot(struct nfs_client *clp, struct nfs4_state *state)
+{
+
+	if (!nfs4_valid_open_stateid(state))
+		return 0;
+	set_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags);
+	/* Don't recover state that expired before the reboot */
+	if (test_bit(NFS_STATE_RECLAIM_NOGRACE, &state->flags)) {
+		clear_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags);
+		return 0;
+	}
+	set_bit(NFS_OWNER_RECLAIM_REBOOT, &state->owner->so_flags);
+	set_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state);
+	return 1;
+}
+
+int nfs4_state_mark_reclaim_nograce(struct nfs_client *clp, struct nfs4_state *state)
+{
+	if (!nfs4_valid_open_stateid(state))
+		return 0;
+	set_bit(NFS_STATE_RECLAIM_NOGRACE, &state->flags);
+	clear_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags);
+	set_bit(NFS_OWNER_RECLAIM_NOGRACE, &state->owner->so_flags);
+	set_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state);
+	return 1;
+}
+
+int nfs4_schedule_stateid_recovery(const struct nfs_server *server, struct nfs4_state *state)
+{
+	struct nfs_client *clp = server->nfs_client;
+
+	if (!nfs4_state_mark_reclaim_nograce(clp, state))
+		return -EBADF;
+	nfs_inode_find_delegation_state_and_recover(state->inode,
+			&state->stateid);
+	dprintk("%s: scheduling stateid recovery for server %s\n", __func__,
+			clp->cl_hostname);
+	nfs4_schedule_state_manager(clp);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs4_schedule_stateid_recovery);
+
+static struct nfs4_lock_state *
+nfs_state_find_lock_state_by_stateid(struct nfs4_state *state,
+		const nfs4_stateid *stateid)
+{
+	struct nfs4_lock_state *pos;
+
+	list_for_each_entry(pos, &state->lock_states, ls_locks) {
+		if (!test_bit(NFS_LOCK_INITIALIZED, &pos->ls_flags))
+			continue;
+		if (nfs4_stateid_match_other(&pos->ls_stateid, stateid))
+			return pos;
+	}
+	return NULL;
+}
+
+static bool nfs_state_lock_state_matches_stateid(struct nfs4_state *state,
+		const nfs4_stateid *stateid)
+{
+	bool found = false;
+
+	if (test_bit(LK_STATE_IN_USE, &state->flags)) {
+		spin_lock(&state->state_lock);
+		if (nfs_state_find_lock_state_by_stateid(state, stateid))
+			found = true;
+		spin_unlock(&state->state_lock);
+	}
+	return found;
+}
+
+void nfs_inode_find_state_and_recover(struct inode *inode,
+		const nfs4_stateid *stateid)
+{
+	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_open_context *ctx;
+	struct nfs4_state *state;
+	bool found = false;
+
+	spin_lock(&inode->i_lock);
+	list_for_each_entry(ctx, &nfsi->open_files, list) {
+		state = ctx->state;
+		if (state == NULL)
+			continue;
+		if (nfs4_stateid_match_other(&state->stateid, stateid) &&
+		    nfs4_state_mark_reclaim_nograce(clp, state)) {
+			found = true;
+			continue;
+		}
+		if (nfs4_stateid_match_other(&state->open_stateid, stateid) &&
+		    nfs4_state_mark_reclaim_nograce(clp, state)) {
+			found = true;
+			continue;
+		}
+		if (nfs_state_lock_state_matches_stateid(state, stateid) &&
+		    nfs4_state_mark_reclaim_nograce(clp, state))
+			found = true;
+	}
+	spin_unlock(&inode->i_lock);
+
+	nfs_inode_find_delegation_state_and_recover(inode, stateid);
+	if (found)
+		nfs4_schedule_state_manager(clp);
+}
+
+static void nfs4_state_mark_open_context_bad(struct nfs4_state *state)
+{
+	struct inode *inode = state->inode;
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_open_context *ctx;
+
+	spin_lock(&inode->i_lock);
+	list_for_each_entry(ctx, &nfsi->open_files, list) {
+		if (ctx->state != state)
+			continue;
+		set_bit(NFS_CONTEXT_BAD, &ctx->flags);
+	}
+	spin_unlock(&inode->i_lock);
+}
+
+static void nfs4_state_mark_recovery_failed(struct nfs4_state *state, int error)
+{
+	set_bit(NFS_STATE_RECOVERY_FAILED, &state->flags);
+	nfs4_state_mark_open_context_bad(state);
+}
+
+
+static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_recovery_ops *ops)
+{
+	struct inode *inode = state->inode;
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct file_lock *fl;
+	struct nfs4_lock_state *lsp;
+	int status = 0;
+	struct file_lock_context *flctx = inode->i_flctx;
+	struct list_head *list;
+
+	if (flctx == NULL)
+		return 0;
+
+	list = &flctx->flc_posix;
+
+	/* Guard against delegation returns and new lock/unlock calls */
+	down_write(&nfsi->rwsem);
+	spin_lock(&flctx->flc_lock);
+restart:
+	list_for_each_entry(fl, list, fl_list) {
+		if (nfs_file_open_context(fl->fl_file)->state != state)
+			continue;
+		spin_unlock(&flctx->flc_lock);
+		status = ops->recover_lock(state, fl);
+		switch (status) {
+		case 0:
+			break;
+		case -ESTALE:
+		case -NFS4ERR_ADMIN_REVOKED:
+		case -NFS4ERR_STALE_STATEID:
+		case -NFS4ERR_BAD_STATEID:
+		case -NFS4ERR_EXPIRED:
+		case -NFS4ERR_NO_GRACE:
+		case -NFS4ERR_STALE_CLIENTID:
+		case -NFS4ERR_BADSESSION:
+		case -NFS4ERR_BADSLOT:
+		case -NFS4ERR_BAD_HIGH_SLOT:
+		case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
+			goto out;
+		default:
+			pr_err("NFS: %s: unhandled error %d\n",
+					__func__, status);
+			/* Fall through */
+		case -ENOMEM:
+		case -NFS4ERR_DENIED:
+		case -NFS4ERR_RECLAIM_BAD:
+		case -NFS4ERR_RECLAIM_CONFLICT:
+			lsp = fl->fl_u.nfs4_fl.owner;
+			if (lsp)
+				set_bit(NFS_LOCK_LOST, &lsp->ls_flags);
+			status = 0;
+		}
+		spin_lock(&flctx->flc_lock);
+	}
+	if (list == &flctx->flc_posix) {
+		list = &flctx->flc_flock;
+		goto restart;
+	}
+	spin_unlock(&flctx->flc_lock);
+out:
+	up_write(&nfsi->rwsem);
+	return status;
+}
+
+static int nfs4_reclaim_open_state(struct nfs4_state_owner *sp, const struct nfs4_state_recovery_ops *ops)
+{
+	struct nfs4_state *state;
+	struct nfs4_lock_state *lock;
+	int status = 0;
+
+	/* Note: we rely on the sp->so_states list being ordered 
+	 * so that we always reclaim open(O_RDWR) and/or open(O_WRITE)
+	 * states first.
+	 * This is needed to ensure that the server won't give us any
+	 * read delegations that we have to return if, say, we are
+	 * recovering after a network partition or a reboot from a
+	 * server that doesn't support a grace period.
+	 */
+	spin_lock(&sp->so_lock);
+	raw_write_seqcount_begin(&sp->so_reclaim_seqcount);
+restart:
+	list_for_each_entry(state, &sp->so_states, open_states) {
+		if (!test_and_clear_bit(ops->state_flag_bit, &state->flags))
+			continue;
+		if (!nfs4_valid_open_stateid(state))
+			continue;
+		if (state->state == 0)
+			continue;
+		atomic_inc(&state->count);
+		spin_unlock(&sp->so_lock);
+		status = ops->recover_open(sp, state);
+		if (status >= 0) {
+			status = nfs4_reclaim_locks(state, ops);
+			if (status >= 0) {
+				if (!test_bit(NFS_DELEGATED_STATE, &state->flags)) {
+					spin_lock(&state->state_lock);
+					list_for_each_entry(lock, &state->lock_states, ls_locks) {
+						if (!test_bit(NFS_LOCK_INITIALIZED, &lock->ls_flags))
+							pr_warn_ratelimited("NFS: "
+									    "%s: Lock reclaim "
+									    "failed!\n", __func__);
+					}
+					spin_unlock(&state->state_lock);
+				}
+				clear_bit(NFS_STATE_RECLAIM_NOGRACE,
+					&state->flags);
+#ifdef CONFIG_NFS_V4_2
+				if (test_bit(NFS_CLNT_DST_SSC_COPY_STATE, &state->flags)) {
+					struct nfs4_copy_state *copy;
+
+					spin_lock(&sp->so_server->nfs_client->cl_lock);
+					list_for_each_entry(copy, &sp->so_server->ss_copies, copies) {
+						if (memcmp(&state->stateid.other, &copy->parent_state->stateid.other, NFS4_STATEID_SIZE))
+							continue;
+						copy->flags = 1;
+						complete(&copy->completion);
+						printk("AGLO: server rebooted waking up the copy\n");
+						break;
+					}
+					spin_unlock(&sp->so_server->nfs_client->cl_lock);
+				}
+#endif /* CONFIG_NFS_V4_2 */
+				nfs4_put_open_state(state);
+				spin_lock(&sp->so_lock);
+				goto restart;
+			}
+		}
+		switch (status) {
+			default:
+				printk(KERN_ERR "NFS: %s: unhandled error %d\n",
+					__func__, status);
+				/* Fall through */
+			case -ENOENT:
+			case -ENOMEM:
+			case -EACCES:
+			case -EROFS:
+			case -EIO:
+			case -ESTALE:
+				/* Open state on this file cannot be recovered */
+				nfs4_state_mark_recovery_failed(state, status);
+				break;
+			case -EAGAIN:
+				ssleep(1);
+				/* Fall through */
+			case -NFS4ERR_ADMIN_REVOKED:
+			case -NFS4ERR_STALE_STATEID:
+			case -NFS4ERR_OLD_STATEID:
+			case -NFS4ERR_BAD_STATEID:
+			case -NFS4ERR_RECLAIM_BAD:
+			case -NFS4ERR_RECLAIM_CONFLICT:
+				nfs4_state_mark_reclaim_nograce(sp->so_server->nfs_client, state);
+				break;
+			case -NFS4ERR_EXPIRED:
+			case -NFS4ERR_NO_GRACE:
+				nfs4_state_mark_reclaim_nograce(sp->so_server->nfs_client, state);
+			case -NFS4ERR_STALE_CLIENTID:
+			case -NFS4ERR_BADSESSION:
+			case -NFS4ERR_BADSLOT:
+			case -NFS4ERR_BAD_HIGH_SLOT:
+			case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
+				goto out_err;
+		}
+		nfs4_put_open_state(state);
+		spin_lock(&sp->so_lock);
+		goto restart;
+	}
+	raw_write_seqcount_end(&sp->so_reclaim_seqcount);
+	spin_unlock(&sp->so_lock);
+	return 0;
+out_err:
+	nfs4_put_open_state(state);
+	spin_lock(&sp->so_lock);
+	raw_write_seqcount_end(&sp->so_reclaim_seqcount);
+	spin_unlock(&sp->so_lock);
+	return status;
+}
+
+static void nfs4_clear_open_state(struct nfs4_state *state)
+{
+	struct nfs4_lock_state *lock;
+
+	clear_bit(NFS_DELEGATED_STATE, &state->flags);
+	clear_bit(NFS_O_RDONLY_STATE, &state->flags);
+	clear_bit(NFS_O_WRONLY_STATE, &state->flags);
+	clear_bit(NFS_O_RDWR_STATE, &state->flags);
+	spin_lock(&state->state_lock);
+	list_for_each_entry(lock, &state->lock_states, ls_locks) {
+		lock->ls_seqid.flags = 0;
+		clear_bit(NFS_LOCK_INITIALIZED, &lock->ls_flags);
+	}
+	spin_unlock(&state->state_lock);
+}
+
+static void nfs4_reset_seqids(struct nfs_server *server,
+	int (*mark_reclaim)(struct nfs_client *clp, struct nfs4_state *state))
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_state_owner *sp;
+	struct rb_node *pos;
+	struct nfs4_state *state;
+
+	spin_lock(&clp->cl_lock);
+	for (pos = rb_first(&server->state_owners);
+	     pos != NULL;
+	     pos = rb_next(pos)) {
+		sp = rb_entry(pos, struct nfs4_state_owner, so_server_node);
+		sp->so_seqid.flags = 0;
+		spin_lock(&sp->so_lock);
+		list_for_each_entry(state, &sp->so_states, open_states) {
+			if (mark_reclaim(clp, state))
+				nfs4_clear_open_state(state);
+		}
+		spin_unlock(&sp->so_lock);
+	}
+	spin_unlock(&clp->cl_lock);
+}
+
+static void nfs4_state_mark_reclaim_helper(struct nfs_client *clp,
+	int (*mark_reclaim)(struct nfs_client *clp, struct nfs4_state *state))
+{
+	struct nfs_server *server;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+		nfs4_reset_seqids(server, mark_reclaim);
+	rcu_read_unlock();
+}
+
+static void nfs4_state_start_reclaim_reboot(struct nfs_client *clp)
+{
+	/* Mark all delegations for reclaim */
+	nfs_delegation_mark_reclaim(clp);
+	nfs4_state_mark_reclaim_helper(clp, nfs4_state_mark_reclaim_reboot);
+}
+
+static int nfs4_reclaim_complete(struct nfs_client *clp,
+				 const struct nfs4_state_recovery_ops *ops,
+				 struct rpc_cred *cred)
+{
+	/* Notify the server we're done reclaiming our state */
+	if (ops->reclaim_complete)
+		return ops->reclaim_complete(clp, cred);
+	return 0;
+}
+
+static void nfs4_clear_reclaim_server(struct nfs_server *server)
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_state_owner *sp;
+	struct rb_node *pos;
+	struct nfs4_state *state;
+
+	spin_lock(&clp->cl_lock);
+	for (pos = rb_first(&server->state_owners);
+	     pos != NULL;
+	     pos = rb_next(pos)) {
+		sp = rb_entry(pos, struct nfs4_state_owner, so_server_node);
+		spin_lock(&sp->so_lock);
+		list_for_each_entry(state, &sp->so_states, open_states) {
+			if (!test_and_clear_bit(NFS_STATE_RECLAIM_REBOOT,
+						&state->flags))
+				continue;
+			nfs4_state_mark_reclaim_nograce(clp, state);
+		}
+		spin_unlock(&sp->so_lock);
+	}
+	spin_unlock(&clp->cl_lock);
+}
+
+static int nfs4_state_clear_reclaim_reboot(struct nfs_client *clp)
+{
+	struct nfs_server *server;
+
+	if (!test_and_clear_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state))
+		return 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+		nfs4_clear_reclaim_server(server);
+	rcu_read_unlock();
+
+	nfs_delegation_reap_unclaimed(clp);
+	return 1;
+}
+
+static void nfs4_state_end_reclaim_reboot(struct nfs_client *clp)
+{
+	const struct nfs4_state_recovery_ops *ops;
+	struct rpc_cred *cred;
+	int err;
+
+	if (!nfs4_state_clear_reclaim_reboot(clp))
+		return;
+	ops = clp->cl_mvops->reboot_recovery_ops;
+	cred = nfs4_get_clid_cred(clp);
+	err = nfs4_reclaim_complete(clp, ops, cred);
+	put_rpccred(cred);
+	if (err == -NFS4ERR_CONN_NOT_BOUND_TO_SESSION)
+		set_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state);
+}
+
+static void nfs4_state_start_reclaim_nograce(struct nfs_client *clp)
+{
+	nfs_mark_test_expired_all_delegations(clp);
+	nfs4_state_mark_reclaim_helper(clp, nfs4_state_mark_reclaim_nograce);
+}
+
+static int nfs4_recovery_handle_error(struct nfs_client *clp, int error)
+{
+	switch (error) {
+		case 0:
+			break;
+		case -NFS4ERR_CB_PATH_DOWN:
+			nfs40_handle_cb_pathdown(clp);
+			break;
+		case -NFS4ERR_NO_GRACE:
+			nfs4_state_end_reclaim_reboot(clp);
+			break;
+		case -NFS4ERR_STALE_CLIENTID:
+			set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
+			nfs4_state_start_reclaim_reboot(clp);
+			break;
+		case -NFS4ERR_EXPIRED:
+			set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
+			nfs4_state_start_reclaim_nograce(clp);
+			break;
+		case -NFS4ERR_BADSESSION:
+		case -NFS4ERR_BADSLOT:
+		case -NFS4ERR_BAD_HIGH_SLOT:
+		case -NFS4ERR_DEADSESSION:
+		case -NFS4ERR_SEQ_FALSE_RETRY:
+		case -NFS4ERR_SEQ_MISORDERED:
+			set_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
+			/* Zero session reset errors */
+			break;
+		case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
+			set_bit(NFS4CLNT_BIND_CONN_TO_SESSION, &clp->cl_state);
+			break;
+		default:
+			dprintk("%s: failed to handle error %d for server %s\n",
+					__func__, error, clp->cl_hostname);
+			return error;
+	}
+	dprintk("%s: handled error %d for server %s\n", __func__, error,
+			clp->cl_hostname);
+	return 0;
+}
+
+static int nfs4_do_reclaim(struct nfs_client *clp, const struct nfs4_state_recovery_ops *ops)
+{
+	struct nfs4_state_owner *sp;
+	struct nfs_server *server;
+	struct rb_node *pos;
+	LIST_HEAD(freeme);
+	int status = 0;
+
+restart:
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		nfs4_purge_state_owners(server, &freeme);
+		spin_lock(&clp->cl_lock);
+		for (pos = rb_first(&server->state_owners);
+		     pos != NULL;
+		     pos = rb_next(pos)) {
+			sp = rb_entry(pos,
+				struct nfs4_state_owner, so_server_node);
+			if (!test_and_clear_bit(ops->owner_flag_bit,
+							&sp->so_flags))
+				continue;
+			if (!atomic_inc_not_zero(&sp->so_count))
+				continue;
+			spin_unlock(&clp->cl_lock);
+			rcu_read_unlock();
+
+			status = nfs4_reclaim_open_state(sp, ops);
+			if (status < 0) {
+				set_bit(ops->owner_flag_bit, &sp->so_flags);
+				nfs4_put_state_owner(sp);
+				status = nfs4_recovery_handle_error(clp, status);
+				return (status != 0) ? status : -EAGAIN;
+			}
+
+			nfs4_put_state_owner(sp);
+			goto restart;
+		}
+		spin_unlock(&clp->cl_lock);
+	}
+	rcu_read_unlock();
+	nfs4_free_state_owners(&freeme);
+	return 0;
+}
+
+static int nfs4_check_lease(struct nfs_client *clp)
+{
+	struct rpc_cred *cred;
+	const struct nfs4_state_maintenance_ops *ops =
+		clp->cl_mvops->state_renewal_ops;
+	int status;
+
+	/* Is the client already known to have an expired lease? */
+	if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state))
+		return 0;
+	spin_lock(&clp->cl_lock);
+	cred = ops->get_state_renewal_cred_locked(clp);
+	spin_unlock(&clp->cl_lock);
+	if (cred == NULL) {
+		cred = nfs4_get_clid_cred(clp);
+		status = -ENOKEY;
+		if (cred == NULL)
+			goto out;
+	}
+	status = ops->renew_lease(clp, cred);
+	put_rpccred(cred);
+	if (status == -ETIMEDOUT) {
+		set_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state);
+		return 0;
+	}
+out:
+	return nfs4_recovery_handle_error(clp, status);
+}
+
+/* Set NFS4CLNT_LEASE_EXPIRED and reclaim reboot state for all v4.0 errors
+ * and for recoverable errors on EXCHANGE_ID for v4.1
+ */
+static int nfs4_handle_reclaim_lease_error(struct nfs_client *clp, int status)
+{
+	switch (status) {
+	case -NFS4ERR_SEQ_MISORDERED:
+		if (test_and_set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state))
+			return -ESERVERFAULT;
+		/* Lease confirmation error: retry after purging the lease */
+		ssleep(1);
+		clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+		break;
+	case -NFS4ERR_STALE_CLIENTID:
+		clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+		nfs4_state_start_reclaim_reboot(clp);
+		break;
+	case -NFS4ERR_CLID_INUSE:
+		pr_err("NFS: Server %s reports our clientid is in use\n",
+			clp->cl_hostname);
+		nfs_mark_client_ready(clp, -EPERM);
+		clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+		return -EPERM;
+	case -EACCES:
+	case -NFS4ERR_DELAY:
+	case -ETIMEDOUT:
+	case -EAGAIN:
+		ssleep(1);
+		break;
+
+	case -NFS4ERR_MINOR_VERS_MISMATCH:
+		if (clp->cl_cons_state == NFS_CS_SESSION_INITING)
+			nfs_mark_client_ready(clp, -EPROTONOSUPPORT);
+		dprintk("%s: exit with error %d for server %s\n",
+				__func__, -EPROTONOSUPPORT, clp->cl_hostname);
+		return -EPROTONOSUPPORT;
+	case -NFS4ERR_NOT_SAME: /* FixMe: implement recovery
+				 * in nfs4_exchange_id */
+	default:
+		dprintk("%s: exit with error %d for server %s\n", __func__,
+				status, clp->cl_hostname);
+		return status;
+	}
+	set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
+	dprintk("%s: handled error %d for server %s\n", __func__, status,
+			clp->cl_hostname);
+	return 0;
+}
+
+static int nfs4_establish_lease(struct nfs_client *clp)
+{
+	struct rpc_cred *cred;
+	const struct nfs4_state_recovery_ops *ops =
+		clp->cl_mvops->reboot_recovery_ops;
+	int status;
+
+	status = nfs4_begin_drain_session(clp);
+	if (status != 0)
+		return status;
+	cred = nfs4_get_clid_cred(clp);
+	if (cred == NULL)
+		return -ENOENT;
+	status = ops->establish_clid(clp, cred);
+	put_rpccred(cred);
+	if (status != 0)
+		return status;
+	pnfs_destroy_all_layouts(clp);
+	return 0;
+}
+
+/*
+ * Returns zero or a negative errno.  NFS4ERR values are converted
+ * to local errno values.
+ */
+static int nfs4_reclaim_lease(struct nfs_client *clp)
+{
+	int status;
+
+	status = nfs4_establish_lease(clp);
+	if (status < 0)
+		return nfs4_handle_reclaim_lease_error(clp, status);
+	if (test_and_clear_bit(NFS4CLNT_SERVER_SCOPE_MISMATCH, &clp->cl_state))
+		nfs4_state_start_reclaim_nograce(clp);
+	if (!test_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state))
+		set_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state);
+	clear_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state);
+	clear_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
+	return 0;
+}
+
+static int nfs4_purge_lease(struct nfs_client *clp)
+{
+	int status;
+
+	status = nfs4_establish_lease(clp);
+	if (status < 0)
+		return nfs4_handle_reclaim_lease_error(clp, status);
+	clear_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
+	set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
+	nfs4_state_start_reclaim_nograce(clp);
+	return 0;
+}
+
+/*
+ * Try remote migration of one FSID from a source server to a
+ * destination server.  The source server provides a list of
+ * potential destinations.
+ *
+ * Returns zero or a negative NFS4ERR status code.
+ */
+static int nfs4_try_migration(struct nfs_server *server, struct rpc_cred *cred)
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct nfs4_fs_locations *locations = NULL;
+	struct inode *inode;
+	struct page *page;
+	int status, result;
+
+	dprintk("--> %s: FSID %llx:%llx on \"%s\"\n", __func__,
+			(unsigned long long)server->fsid.major,
+			(unsigned long long)server->fsid.minor,
+			clp->cl_hostname);
+
+	result = 0;
+	page = alloc_page(GFP_KERNEL);
+	locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
+	if (page == NULL || locations == NULL) {
+		dprintk("<-- %s: no memory\n", __func__);
+		goto out;
+	}
+
+	inode = d_inode(server->super->s_root);
+	result = nfs4_proc_get_locations(inode, locations, page, cred);
+	if (result) {
+		dprintk("<-- %s: failed to retrieve fs_locations: %d\n",
+			__func__, result);
+		goto out;
+	}
+
+	result = -NFS4ERR_NXIO;
+	if (!locations->nlocations)
+		goto out;
+
+	if (!(locations->fattr.valid & NFS_ATTR_FATTR_V4_LOCATIONS)) {
+		dprintk("<-- %s: No fs_locations data, migration skipped\n",
+			__func__);
+		goto out;
+	}
+
+	status = nfs4_begin_drain_session(clp);
+	if (status != 0)
+		return status;
+
+	status = nfs4_replace_transport(server, locations);
+	if (status != 0) {
+		dprintk("<-- %s: failed to replace transport: %d\n",
+			__func__, status);
+		goto out;
+	}
+
+	result = 0;
+	dprintk("<-- %s: migration succeeded\n", __func__);
+
+out:
+	if (page != NULL)
+		__free_page(page);
+	kfree(locations);
+	if (result) {
+		pr_err("NFS: migration recovery failed (server %s)\n",
+				clp->cl_hostname);
+		set_bit(NFS_MIG_FAILED, &server->mig_status);
+	}
+	return result;
+}
+
+/*
+ * Returns zero or a negative NFS4ERR status code.
+ */
+static int nfs4_handle_migration(struct nfs_client *clp)
+{
+	const struct nfs4_state_maintenance_ops *ops =
+				clp->cl_mvops->state_renewal_ops;
+	struct nfs_server *server;
+	struct rpc_cred *cred;
+
+	dprintk("%s: migration reported on \"%s\"\n", __func__,
+			clp->cl_hostname);
+
+	spin_lock(&clp->cl_lock);
+	cred = ops->get_state_renewal_cred_locked(clp);
+	spin_unlock(&clp->cl_lock);
+	if (cred == NULL)
+		return -NFS4ERR_NOENT;
+
+	clp->cl_mig_gen++;
+restart:
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		int status;
+
+		if (server->mig_gen == clp->cl_mig_gen)
+			continue;
+		server->mig_gen = clp->cl_mig_gen;
+
+		if (!test_and_clear_bit(NFS_MIG_IN_TRANSITION,
+						&server->mig_status))
+			continue;
+
+		rcu_read_unlock();
+		status = nfs4_try_migration(server, cred);
+		if (status < 0) {
+			put_rpccred(cred);
+			return status;
+		}
+		goto restart;
+	}
+	rcu_read_unlock();
+	put_rpccred(cred);
+	return 0;
+}
+
+/*
+ * Test each nfs_server on the clp's cl_superblocks list to see
+ * if it's moved to another server.  Stop when the server no longer
+ * returns NFS4ERR_LEASE_MOVED.
+ */
+static int nfs4_handle_lease_moved(struct nfs_client *clp)
+{
+	const struct nfs4_state_maintenance_ops *ops =
+				clp->cl_mvops->state_renewal_ops;
+	struct nfs_server *server;
+	struct rpc_cred *cred;
+
+	dprintk("%s: lease moved reported on \"%s\"\n", __func__,
+			clp->cl_hostname);
+
+	spin_lock(&clp->cl_lock);
+	cred = ops->get_state_renewal_cred_locked(clp);
+	spin_unlock(&clp->cl_lock);
+	if (cred == NULL)
+		return -NFS4ERR_NOENT;
+
+	clp->cl_mig_gen++;
+restart:
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		struct inode *inode;
+		int status;
+
+		if (server->mig_gen == clp->cl_mig_gen)
+			continue;
+		server->mig_gen = clp->cl_mig_gen;
+
+		rcu_read_unlock();
+
+		inode = d_inode(server->super->s_root);
+		status = nfs4_proc_fsid_present(inode, cred);
+		if (status != -NFS4ERR_MOVED)
+			goto restart;	/* wasn't this one */
+		if (nfs4_try_migration(server, cred) == -NFS4ERR_LEASE_MOVED)
+			goto restart;	/* there are more */
+		goto out;
+	}
+	rcu_read_unlock();
+
+out:
+	put_rpccred(cred);
+	return 0;
+}
+
+/**
+ * nfs4_discover_server_trunking - Detect server IP address trunking
+ *
+ * @clp: nfs_client under test
+ * @result: OUT: found nfs_client, or clp
+ *
+ * Returns zero or a negative errno.  If zero is returned,
+ * an nfs_client pointer is planted in "result".
+ *
+ * Note: since we are invoked in process context, and
+ * not from inside the state manager, we cannot use
+ * nfs4_handle_reclaim_lease_error().
+ */
+int nfs4_discover_server_trunking(struct nfs_client *clp,
+				  struct nfs_client **result)
+{
+	const struct nfs4_state_recovery_ops *ops =
+				clp->cl_mvops->reboot_recovery_ops;
+	struct rpc_clnt *clnt;
+	struct rpc_cred *cred;
+	int i, status;
+
+	dprintk("NFS: %s: testing '%s'\n", __func__, clp->cl_hostname);
+
+	clnt = clp->cl_rpcclient;
+	i = 0;
+
+	mutex_lock(&nfs_clid_init_mutex);
+again:
+	status  = -ENOENT;
+	cred = nfs4_get_clid_cred(clp);
+	if (cred == NULL)
+		goto out_unlock;
+
+	status = ops->detect_trunking(clp, result, cred);
+	put_rpccred(cred);
+	switch (status) {
+	case 0:
+	case -EINTR:
+	case -ERESTARTSYS:
+		break;
+	case -ETIMEDOUT:
+		if (clnt->cl_softrtry)
+			break;
+		/* Fall through */
+	case -NFS4ERR_DELAY:
+	case -EAGAIN:
+		ssleep(1);
+		/* Fall through */
+	case -NFS4ERR_STALE_CLIENTID:
+		dprintk("NFS: %s after status %d, retrying\n",
+			__func__, status);
+		goto again;
+	case -EACCES:
+		if (i++ == 0) {
+			nfs4_root_machine_cred(clp);
+			goto again;
+		}
+		if (clnt->cl_auth->au_flavor == RPC_AUTH_UNIX)
+			break;
+		/* Fall through */
+	case -NFS4ERR_CLID_INUSE:
+	case -NFS4ERR_WRONGSEC:
+		/* No point in retrying if we already used RPC_AUTH_UNIX */
+		if (clnt->cl_auth->au_flavor == RPC_AUTH_UNIX) {
+			status = -EPERM;
+			break;
+		}
+		clnt = rpc_clone_client_set_auth(clnt, RPC_AUTH_UNIX);
+		if (IS_ERR(clnt)) {
+			status = PTR_ERR(clnt);
+			break;
+		}
+		/* Note: this is safe because we haven't yet marked the
+		 * client as ready, so we are the only user of
+		 * clp->cl_rpcclient
+		 */
+		clnt = xchg(&clp->cl_rpcclient, clnt);
+		rpc_shutdown_client(clnt);
+		clnt = clp->cl_rpcclient;
+		goto again;
+
+	case -NFS4ERR_MINOR_VERS_MISMATCH:
+		status = -EPROTONOSUPPORT;
+		break;
+
+	case -EKEYEXPIRED:
+	case -NFS4ERR_NOT_SAME: /* FixMe: implement recovery
+				 * in nfs4_exchange_id */
+		status = -EKEYEXPIRED;
+		break;
+	default:
+		pr_warn("NFS: %s unhandled error %d. Exiting with error EIO\n",
+				__func__, status);
+		status = -EIO;
+	}
+
+out_unlock:
+	mutex_unlock(&nfs_clid_init_mutex);
+	dprintk("NFS: %s: status = %d\n", __func__, status);
+	return status;
+}
+
+#ifdef CONFIG_NFS_V4_1
+void nfs4_schedule_session_recovery(struct nfs4_session *session, int err)
+{
+	struct nfs_client *clp = session->clp;
+
+	switch (err) {
+	default:
+		set_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
+		break;
+	case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
+		set_bit(NFS4CLNT_BIND_CONN_TO_SESSION, &clp->cl_state);
+	}
+	nfs4_schedule_state_manager(clp);
+}
+EXPORT_SYMBOL_GPL(nfs4_schedule_session_recovery);
+
+void nfs41_notify_server(struct nfs_client *clp)
+{
+	/* Use CHECK_LEASE to ping the server with a SEQUENCE */
+	set_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state);
+	nfs4_schedule_state_manager(clp);
+}
+
+static void nfs4_reset_all_state(struct nfs_client *clp)
+{
+	if (test_and_set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0) {
+		set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
+		clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+		nfs4_state_start_reclaim_nograce(clp);
+		dprintk("%s: scheduling reset of all state for server %s!\n",
+				__func__, clp->cl_hostname);
+		nfs4_schedule_state_manager(clp);
+	}
+}
+
+static void nfs41_handle_server_reboot(struct nfs_client *clp)
+{
+	if (test_and_set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0) {
+		nfs4_state_start_reclaim_reboot(clp);
+		dprintk("%s: server %s rebooted!\n", __func__,
+				clp->cl_hostname);
+		nfs4_schedule_state_manager(clp);
+	}
+}
+
+static void nfs41_handle_all_state_revoked(struct nfs_client *clp)
+{
+	nfs4_reset_all_state(clp);
+	dprintk("%s: state revoked on server %s\n", __func__, clp->cl_hostname);
+}
+
+static void nfs41_handle_some_state_revoked(struct nfs_client *clp)
+{
+	nfs4_state_start_reclaim_nograce(clp);
+	nfs4_schedule_state_manager(clp);
+
+	dprintk("%s: state revoked on server %s\n", __func__, clp->cl_hostname);
+}
+
+static void nfs41_handle_recallable_state_revoked(struct nfs_client *clp)
+{
+	/* FIXME: For now, we destroy all layouts. */
+	pnfs_destroy_all_layouts(clp);
+	/* FIXME: For now, we test all delegations+open state+locks. */
+	nfs41_handle_some_state_revoked(clp);
+	dprintk("%s: Recallable state revoked on server %s!\n", __func__,
+			clp->cl_hostname);
+}
+
+static void nfs41_handle_backchannel_fault(struct nfs_client *clp)
+{
+	set_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
+	nfs4_schedule_state_manager(clp);
+
+	dprintk("%s: server %s declared a backchannel fault\n", __func__,
+			clp->cl_hostname);
+}
+
+static void nfs41_handle_cb_path_down(struct nfs_client *clp)
+{
+	if (test_and_set_bit(NFS4CLNT_BIND_CONN_TO_SESSION,
+		&clp->cl_state) == 0)
+		nfs4_schedule_state_manager(clp);
+}
+
+void nfs41_handle_sequence_flag_errors(struct nfs_client *clp, u32 flags,
+		bool recovery)
+{
+	if (!flags)
+		return;
+
+	dprintk("%s: \"%s\" (client ID %llx) flags=0x%08x\n",
+		__func__, clp->cl_hostname, clp->cl_clientid, flags);
+	/*
+	 * If we're called from the state manager thread, then assume we're
+	 * already handling the RECLAIM_NEEDED and/or STATE_REVOKED.
+	 * Those flags are expected to remain set until we're done
+	 * recovering (see RFC5661, section 18.46.3).
+	 */
+	if (recovery)
+		goto out_recovery;
+
+	if (flags & SEQ4_STATUS_RESTART_RECLAIM_NEEDED)
+		nfs41_handle_server_reboot(clp);
+	if (flags & (SEQ4_STATUS_EXPIRED_ALL_STATE_REVOKED))
+		nfs41_handle_all_state_revoked(clp);
+	if (flags & (SEQ4_STATUS_EXPIRED_SOME_STATE_REVOKED |
+			    SEQ4_STATUS_ADMIN_STATE_REVOKED))
+		nfs41_handle_some_state_revoked(clp);
+	if (flags & SEQ4_STATUS_LEASE_MOVED)
+		nfs4_schedule_lease_moved_recovery(clp);
+	if (flags & SEQ4_STATUS_RECALLABLE_STATE_REVOKED)
+		nfs41_handle_recallable_state_revoked(clp);
+out_recovery:
+	if (flags & SEQ4_STATUS_BACKCHANNEL_FAULT)
+		nfs41_handle_backchannel_fault(clp);
+	else if (flags & (SEQ4_STATUS_CB_PATH_DOWN |
+				SEQ4_STATUS_CB_PATH_DOWN_SESSION))
+		nfs41_handle_cb_path_down(clp);
+}
+
+static int nfs4_reset_session(struct nfs_client *clp)
+{
+	struct rpc_cred *cred;
+	int status;
+
+	if (!nfs4_has_session(clp))
+		return 0;
+	status = nfs4_begin_drain_session(clp);
+	if (status != 0)
+		return status;
+	cred = nfs4_get_clid_cred(clp);
+	status = nfs4_proc_destroy_session(clp->cl_session, cred);
+	switch (status) {
+	case 0:
+	case -NFS4ERR_BADSESSION:
+	case -NFS4ERR_DEADSESSION:
+		break;
+	case -NFS4ERR_BACK_CHAN_BUSY:
+	case -NFS4ERR_DELAY:
+		set_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
+		status = 0;
+		ssleep(1);
+		goto out;
+	default:
+		status = nfs4_recovery_handle_error(clp, status);
+		goto out;
+	}
+
+	memset(clp->cl_session->sess_id.data, 0, NFS4_MAX_SESSIONID_LEN);
+	status = nfs4_proc_create_session(clp, cred);
+	if (status) {
+		dprintk("%s: session reset failed with status %d for server %s!\n",
+			__func__, status, clp->cl_hostname);
+		status = nfs4_handle_reclaim_lease_error(clp, status);
+		goto out;
+	}
+	nfs41_finish_session_reset(clp);
+	dprintk("%s: session reset was successful for server %s!\n",
+			__func__, clp->cl_hostname);
+out:
+	if (cred)
+		put_rpccred(cred);
+	return status;
+}
+
+static int nfs4_bind_conn_to_session(struct nfs_client *clp)
+{
+	struct rpc_cred *cred;
+	int ret;
+
+	if (!nfs4_has_session(clp))
+		return 0;
+	ret = nfs4_begin_drain_session(clp);
+	if (ret != 0)
+		return ret;
+	cred = nfs4_get_clid_cred(clp);
+	ret = nfs4_proc_bind_conn_to_session(clp, cred);
+	if (cred)
+		put_rpccred(cred);
+	clear_bit(NFS4CLNT_BIND_CONN_TO_SESSION, &clp->cl_state);
+	switch (ret) {
+	case 0:
+		dprintk("%s: bind_conn_to_session was successful for server %s!\n",
+			__func__, clp->cl_hostname);
+		break;
+	case -NFS4ERR_DELAY:
+		ssleep(1);
+		set_bit(NFS4CLNT_BIND_CONN_TO_SESSION, &clp->cl_state);
+		break;
+	default:
+		return nfs4_recovery_handle_error(clp, ret);
+	}
+	return 0;
+}
+#else /* CONFIG_NFS_V4_1 */
+static int nfs4_reset_session(struct nfs_client *clp) { return 0; }
+
+static int nfs4_bind_conn_to_session(struct nfs_client *clp)
+{
+	return 0;
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+static void nfs4_state_manager(struct nfs_client *clp)
+{
+	unsigned int memflags;
+	int status = 0;
+	const char *section = "", *section_sep = "";
+
+	/*
+	 * State recovery can deadlock if the direct reclaim code tries
+	 * start NFS writeback. So ensure memory allocations are all
+	 * GFP_NOFS.
+	 */
+	memflags = memalloc_nofs_save();
+
+	/* Ensure exclusive access to NFSv4 state */
+	do {
+		clear_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
+		if (test_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state)) {
+			section = "purge state";
+			status = nfs4_purge_lease(clp);
+			if (status < 0)
+				goto out_error;
+			continue;
+		}
+
+		if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state)) {
+			section = "lease expired";
+			/* We're going to have to re-establish a clientid */
+			status = nfs4_reclaim_lease(clp);
+			if (status < 0)
+				goto out_error;
+			continue;
+		}
+
+		/* Initialize or reset the session */
+		if (test_and_clear_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state)) {
+			section = "reset session";
+			status = nfs4_reset_session(clp);
+			if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state))
+				continue;
+			if (status < 0)
+				goto out_error;
+		}
+
+		/* Send BIND_CONN_TO_SESSION */
+		if (test_and_clear_bit(NFS4CLNT_BIND_CONN_TO_SESSION,
+				&clp->cl_state)) {
+			section = "bind conn to session";
+			status = nfs4_bind_conn_to_session(clp);
+			if (status < 0)
+				goto out_error;
+			continue;
+		}
+
+		if (test_and_clear_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state)) {
+			section = "check lease";
+			status = nfs4_check_lease(clp);
+			if (status < 0)
+				goto out_error;
+			continue;
+		}
+
+		if (test_and_clear_bit(NFS4CLNT_MOVED, &clp->cl_state)) {
+			section = "migration";
+			status = nfs4_handle_migration(clp);
+			if (status < 0)
+				goto out_error;
+		}
+
+		if (test_and_clear_bit(NFS4CLNT_LEASE_MOVED, &clp->cl_state)) {
+			section = "lease moved";
+			status = nfs4_handle_lease_moved(clp);
+			if (status < 0)
+				goto out_error;
+		}
+
+		/* First recover reboot state... */
+		if (test_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state)) {
+			section = "reclaim reboot";
+			status = nfs4_do_reclaim(clp,
+				clp->cl_mvops->reboot_recovery_ops);
+			if (status == -EAGAIN)
+				continue;
+			if (status < 0)
+				goto out_error;
+			nfs4_state_end_reclaim_reboot(clp);
+		}
+
+		/* Detect expired delegations... */
+		if (test_and_clear_bit(NFS4CLNT_DELEGATION_EXPIRED, &clp->cl_state)) {
+			section = "detect expired delegations";
+			nfs_reap_expired_delegations(clp);
+			continue;
+		}
+
+		/* Now recover expired state... */
+		if (test_and_clear_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state)) {
+			section = "reclaim nograce";
+			status = nfs4_do_reclaim(clp,
+				clp->cl_mvops->nograce_recovery_ops);
+			if (status == -EAGAIN)
+				continue;
+			if (status < 0)
+				goto out_error;
+		}
+
+		memalloc_nofs_restore(memflags);
+		nfs4_end_drain_session(clp);
+		nfs4_clear_state_manager_bit(clp);
+
+		if (!test_and_set_bit(NFS4CLNT_DELEGRETURN_RUNNING, &clp->cl_state)) {
+			if (test_and_clear_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state)) {
+				nfs_client_return_marked_delegations(clp);
+				set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
+			}
+			clear_bit(NFS4CLNT_DELEGRETURN_RUNNING, &clp->cl_state);
+		}
+
+		/* Did we race with an attempt to give us more work? */
+		if (!test_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state))
+			return;
+		if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
+			return;
+		memflags = memalloc_nofs_save();
+	} while (refcount_read(&clp->cl_count) > 1 && !signalled());
+	goto out_drain;
+
+out_error:
+	if (strlen(section))
+		section_sep = ": ";
+	pr_warn_ratelimited("NFS: state manager%s%s failed on NFSv4 server %s"
+			" with error %d\n", section_sep, section,
+			clp->cl_hostname, -status);
+	ssleep(1);
+out_drain:
+	memalloc_nofs_restore(memflags);
+	nfs4_end_drain_session(clp);
+	nfs4_clear_state_manager_bit(clp);
+}
+
+static int nfs4_run_state_manager(void *ptr)
+{
+	struct nfs_client *clp = ptr;
+
+	allow_signal(SIGKILL);
+	nfs4_state_manager(clp);
+	nfs_put_client(clp);
+	module_put_and_exit(0);
+	return 0;
+}
+
+/*
+ * Local variables:
+ *  c-basic-offset: 8
+ * End:
+ */