Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 1355 insertions, 0 deletions

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
new file mode 100644
index 000000000..d3051b051
--- /dev/null
+++ b/fs/nfs/nfs4client.c
@@ -0,0 +1,1355 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#include <linux/module.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/auth.h>
+#include <linux/sunrpc/xprt.h>
+#include <linux/sunrpc/bc_xprt.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
+#include "internal.h"
+#include "callback.h"
+#include "delegation.h"
+#include "nfs4session.h"
+#include "nfs4idmap.h"
+#include "pnfs.h"
+#include "netns.h"
+
+#define NFSDBG_FACILITY		NFSDBG_CLIENT
+
+/*
+ * Get a unique NFSv4.0 callback identifier which will be used
+ * by the V4.0 callback service to lookup the nfs_client struct
+ */
+static int nfs_get_cb_ident_idr(struct nfs_client *clp, int minorversion)
+{
+	int ret = 0;
+	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
+
+	if (clp->rpc_ops->version != 4 || minorversion != 0)
+		return ret;
+	idr_preload(GFP_KERNEL);
+	spin_lock(&nn->nfs_client_lock);
+	ret = idr_alloc(&nn->cb_ident_idr, clp, 1, 0, GFP_NOWAIT);
+	if (ret >= 0)
+		clp->cl_cb_ident = ret;
+	spin_unlock(&nn->nfs_client_lock);
+	idr_preload_end();
+	return ret < 0 ? ret : 0;
+}
+
+#ifdef CONFIG_NFS_V4_1
+/*
+ * Per auth flavor data server rpc clients
+ */
+struct nfs4_ds_server {
+	struct list_head	list;   /* ds_clp->cl_ds_clients */
+	struct rpc_clnt		*rpc_clnt;
+};
+
+/**
+ * nfs4_find_ds_client - Common lookup case for DS I/O
+ * @ds_clp: pointer to the DS's nfs_client
+ * @flavor: rpc auth flavour to match
+ */
+static struct nfs4_ds_server *
+nfs4_find_ds_client(struct nfs_client *ds_clp, rpc_authflavor_t flavor)
+{
+	struct nfs4_ds_server *dss;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(dss, &ds_clp->cl_ds_clients, list) {
+		if (dss->rpc_clnt->cl_auth->au_flavor != flavor)
+			continue;
+		goto out;
+	}
+	dss = NULL;
+out:
+	rcu_read_unlock();
+	return dss;
+}
+
+static struct nfs4_ds_server *
+nfs4_add_ds_client(struct nfs_client *ds_clp, rpc_authflavor_t flavor,
+			   struct nfs4_ds_server *new)
+{
+	struct nfs4_ds_server *dss;
+
+	spin_lock(&ds_clp->cl_lock);
+	list_for_each_entry(dss, &ds_clp->cl_ds_clients, list) {
+		if (dss->rpc_clnt->cl_auth->au_flavor != flavor)
+			continue;
+		goto out;
+	}
+	if (new)
+		list_add_rcu(&new->list, &ds_clp->cl_ds_clients);
+	dss = new;
+out:
+	spin_unlock(&ds_clp->cl_lock); /* need some lock to protect list */
+	return dss;
+}
+
+static struct nfs4_ds_server *
+nfs4_alloc_ds_server(struct nfs_client *ds_clp, rpc_authflavor_t flavor)
+{
+	struct nfs4_ds_server *dss;
+
+	dss = kmalloc(sizeof(*dss), GFP_NOFS);
+	if (dss == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	dss->rpc_clnt = rpc_clone_client_set_auth(ds_clp->cl_rpcclient, flavor);
+	if (IS_ERR(dss->rpc_clnt)) {
+		int err = PTR_ERR(dss->rpc_clnt);
+		kfree (dss);
+		return ERR_PTR(err);
+	}
+	INIT_LIST_HEAD(&dss->list);
+
+	return dss;
+}
+
+static void
+nfs4_free_ds_server(struct nfs4_ds_server *dss)
+{
+	rpc_release_client(dss->rpc_clnt);
+	kfree(dss);
+}
+
+/**
+ * nfs4_find_or_create_ds_client - Find or create a DS rpc client
+ * @ds_clp: pointer to the DS's nfs_client
+ * @inode: pointer to the inode
+ *
+ * Find or create a DS rpc client with th MDS server rpc client auth flavor
+ * in the nfs_client cl_ds_clients list.
+ */
+struct rpc_clnt *
+nfs4_find_or_create_ds_client(struct nfs_client *ds_clp, struct inode *inode)
+{
+	struct nfs4_ds_server *dss, *new;
+	rpc_authflavor_t flavor = NFS_SERVER(inode)->client->cl_auth->au_flavor;
+
+	dss = nfs4_find_ds_client(ds_clp, flavor);
+	if (dss != NULL)
+		goto out;
+	new = nfs4_alloc_ds_server(ds_clp, flavor);
+	if (IS_ERR(new))
+		return ERR_CAST(new);
+	dss = nfs4_add_ds_client(ds_clp, flavor, new);
+	if (dss != new)
+		nfs4_free_ds_server(new);
+out:
+	return dss->rpc_clnt;
+}
+EXPORT_SYMBOL_GPL(nfs4_find_or_create_ds_client);
+
+static void
+nfs4_shutdown_ds_clients(struct nfs_client *clp)
+{
+	struct nfs4_ds_server *dss;
+
+	while (!list_empty(&clp->cl_ds_clients)) {
+		dss = list_entry(clp->cl_ds_clients.next,
+					struct nfs4_ds_server, list);
+		list_del(&dss->list);
+		rpc_shutdown_client(dss->rpc_clnt);
+		kfree (dss);
+	}
+}
+
+static void
+nfs4_cleanup_callback(struct nfs_client *clp)
+{
+	struct nfs4_copy_state *cp_state;
+
+	while (!list_empty(&clp->pending_cb_stateids)) {
+		cp_state = list_entry(clp->pending_cb_stateids.next,
+					struct nfs4_copy_state, copies);
+		list_del(&cp_state->copies);
+		kfree(cp_state);
+	}
+}
+
+void nfs41_shutdown_client(struct nfs_client *clp)
+{
+	if (nfs4_has_session(clp)) {
+		nfs4_cleanup_callback(clp);
+		nfs4_shutdown_ds_clients(clp);
+		nfs4_destroy_session(clp->cl_session);
+		nfs4_destroy_clientid(clp);
+	}
+
+}
+#endif	/* CONFIG_NFS_V4_1 */
+
+void nfs40_shutdown_client(struct nfs_client *clp)
+{
+	if (clp->cl_slot_tbl) {
+		nfs4_shutdown_slot_table(clp->cl_slot_tbl);
+		kfree(clp->cl_slot_tbl);
+	}
+}
+
+struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *cl_init)
+{
+	char buf[INET6_ADDRSTRLEN + 1];
+	const char *ip_addr = cl_init->ip_addr;
+	struct nfs_client *clp = nfs_alloc_client(cl_init);
+	int err;
+
+	if (IS_ERR(clp))
+		return clp;
+
+	err = nfs_get_cb_ident_idr(clp, cl_init->minorversion);
+	if (err)
+		goto error;
+
+	if (cl_init->minorversion > NFS4_MAX_MINOR_VERSION) {
+		err = -EINVAL;
+		goto error;
+	}
+
+	spin_lock_init(&clp->cl_lock);
+	INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
+	INIT_LIST_HEAD(&clp->cl_ds_clients);
+	rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
+	clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;
+	clp->cl_mvops = nfs_v4_minor_ops[cl_init->minorversion];
+	clp->cl_mig_gen = 1;
+#if IS_ENABLED(CONFIG_NFS_V4_1)
+	init_waitqueue_head(&clp->cl_lock_waitq);
+#endif
+	INIT_LIST_HEAD(&clp->pending_cb_stateids);
+
+	if (cl_init->minorversion != 0)
+		__set_bit(NFS_CS_INFINITE_SLOTS, &clp->cl_flags);
+	__set_bit(NFS_CS_DISCRTRY, &clp->cl_flags);
+	__set_bit(NFS_CS_NO_RETRANS_TIMEOUT, &clp->cl_flags);
+
+	/*
+	 * Set up the connection to the server before we add add to the
+	 * global list.
+	 */
+	err = nfs_create_rpc_client(clp, cl_init, RPC_AUTH_GSS_KRB5I);
+	if (err == -EINVAL)
+		err = nfs_create_rpc_client(clp, cl_init, RPC_AUTH_UNIX);
+	if (err < 0)
+		goto error;
+
+	/* If no clientaddr= option was specified, find a usable cb address */
+	if (ip_addr == NULL) {
+		struct sockaddr_storage cb_addr;
+		struct sockaddr *sap = (struct sockaddr *)&cb_addr;
+
+		err = rpc_localaddr(clp->cl_rpcclient, sap, sizeof(cb_addr));
+		if (err < 0)
+			goto error;
+		err = rpc_ntop(sap, buf, sizeof(buf));
+		if (err < 0)
+			goto error;
+		ip_addr = (const char *)buf;
+	}
+	strscpy(clp->cl_ipaddr, ip_addr, sizeof(clp->cl_ipaddr));
+
+	err = nfs_idmap_new(clp);
+	if (err < 0) {
+		dprintk("%s: failed to create idmapper. Error = %d\n",
+			__func__, err);
+		goto error;
+	}
+	__set_bit(NFS_CS_IDMAP, &clp->cl_res_state);
+	return clp;
+
+error:
+	nfs_free_client(clp);
+	return ERR_PTR(err);
+}
+
+/*
+ * Destroy the NFS4 callback service
+ */
+static void nfs4_destroy_callback(struct nfs_client *clp)
+{
+	if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
+		nfs_callback_down(clp->cl_mvops->minor_version, clp->cl_net);
+}
+
+static void nfs4_shutdown_client(struct nfs_client *clp)
+{
+	if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
+		nfs4_kill_renewd(clp);
+	clp->cl_mvops->shutdown_client(clp);
+	nfs4_destroy_callback(clp);
+	if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
+		nfs_idmap_delete(clp);
+
+	rpc_destroy_wait_queue(&clp->cl_rpcwaitq);
+	kfree(clp->cl_serverowner);
+	kfree(clp->cl_serverscope);
+	kfree(clp->cl_implid);
+	kfree(clp->cl_owner_id);
+}
+
+void nfs4_free_client(struct nfs_client *clp)
+{
+	nfs4_shutdown_client(clp);
+	nfs_free_client(clp);
+}
+
+/*
+ * Initialize the NFS4 callback service
+ */
+static int nfs4_init_callback(struct nfs_client *clp)
+{
+	struct rpc_xprt *xprt;
+	int error;
+
+	xprt = rcu_dereference_raw(clp->cl_rpcclient->cl_xprt);
+
+	if (nfs4_has_session(clp)) {
+		error = xprt_setup_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
+		if (error < 0)
+			return error;
+	}
+
+	error = nfs_callback_up(clp->cl_mvops->minor_version, xprt);
+	if (error < 0) {
+		dprintk("%s: failed to start callback. Error = %d\n",
+			__func__, error);
+		return error;
+	}
+	__set_bit(NFS_CS_CALLBACK, &clp->cl_res_state);
+
+	return 0;
+}
+
+/**
+ * nfs40_init_client - nfs_client initialization tasks for NFSv4.0
+ * @clp: nfs_client to initialize
+ *
+ * Returns zero on success, or a negative errno if some error occurred.
+ */
+int nfs40_init_client(struct nfs_client *clp)
+{
+	struct nfs4_slot_table *tbl;
+	int ret;
+
+	tbl = kzalloc(sizeof(*tbl), GFP_NOFS);
+	if (tbl == NULL)
+		return -ENOMEM;
+
+	ret = nfs4_setup_slot_table(tbl, NFS4_MAX_SLOT_TABLE,
+					"NFSv4.0 transport Slot table");
+	if (ret) {
+		nfs4_shutdown_slot_table(tbl);
+		kfree(tbl);
+		return ret;
+	}
+
+	clp->cl_slot_tbl = tbl;
+	return 0;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+
+/**
+ * nfs41_init_client - nfs_client initialization tasks for NFSv4.1+
+ * @clp: nfs_client to initialize
+ *
+ * Returns zero on success, or a negative errno if some error occurred.
+ */
+int nfs41_init_client(struct nfs_client *clp)
+{
+	struct nfs4_session *session = NULL;
+
+	/*
+	 * Create the session and mark it expired.
+	 * When a SEQUENCE operation encounters the expired session
+	 * it will do session recovery to initialize it.
+	 */
+	session = nfs4_alloc_session(clp);
+	if (!session)
+		return -ENOMEM;
+
+	clp->cl_session = session;
+
+	/*
+	 * The create session reply races with the server back
+	 * channel probe. Mark the client NFS_CS_SESSION_INITING
+	 * so that the client back channel can find the
+	 * nfs_client struct
+	 */
+	nfs_mark_client_ready(clp, NFS_CS_SESSION_INITING);
+	return 0;
+}
+
+#endif	/* CONFIG_NFS_V4_1 */
+
+/*
+ * Initialize the minor version specific parts of an NFS4 client record
+ */
+static int nfs4_init_client_minor_version(struct nfs_client *clp)
+{
+	int ret;
+
+	ret = clp->cl_mvops->init_client(clp);
+	if (ret)
+		return ret;
+	return nfs4_init_callback(clp);
+}
+
+static void nfs4_add_trunk(struct nfs_client *clp, struct nfs_client *old)
+{
+	struct sockaddr_storage clp_addr, old_addr;
+	struct sockaddr *clp_sap = (struct sockaddr *)&clp_addr;
+	struct sockaddr *old_sap = (struct sockaddr *)&old_addr;
+	size_t clp_salen;
+	struct xprt_create xprt_args = {
+		.ident = old->cl_proto,
+		.net = old->cl_net,
+		.servername = old->cl_hostname,
+	};
+
+	if (clp->cl_proto != old->cl_proto)
+		return;
+	clp_salen = rpc_peeraddr(clp->cl_rpcclient, clp_sap, sizeof(clp_addr));
+	rpc_peeraddr(old->cl_rpcclient, old_sap, sizeof(old_addr));
+
+	if (clp_addr.ss_family != old_addr.ss_family)
+		return;
+
+	xprt_args.dstaddr = clp_sap;
+	xprt_args.addrlen = clp_salen;
+
+	rpc_clnt_add_xprt(old->cl_rpcclient, &xprt_args,
+			  rpc_clnt_test_and_add_xprt, NULL);
+}
+
+/**
+ * nfs4_init_client - Initialise an NFS4 client record
+ *
+ * @clp: nfs_client to initialise
+ * @cl_init: pointer to nfs_client_initdata
+ *
+ * Returns pointer to an NFS client, or an ERR_PTR value.
+ */
+struct nfs_client *nfs4_init_client(struct nfs_client *clp,
+				    const struct nfs_client_initdata *cl_init)
+{
+	struct nfs_client *old;
+	int error;
+
+	if (clp->cl_cons_state == NFS_CS_READY)
+		/* the client is initialised already */
+		return clp;
+
+	error = nfs4_init_client_minor_version(clp);
+	if (error < 0)
+		goto error;
+
+	error = nfs4_discover_server_trunking(clp, &old);
+	if (error < 0)
+		goto error;
+
+	if (clp != old) {
+		clp->cl_preserve_clid = true;
+		/*
+		 * Mark the client as having failed initialization so other
+		 * processes walking the nfs_client_list in nfs_match_client()
+		 * won't try to use it.
+		 */
+		nfs_mark_client_ready(clp, -EPERM);
+		if (old->cl_mvops->session_trunk)
+			nfs4_add_trunk(clp, old);
+	}
+	clear_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags);
+	nfs_put_client(clp);
+	return old;
+
+error:
+	nfs_mark_client_ready(clp, error);
+	nfs_put_client(clp);
+	return ERR_PTR(error);
+}
+
+/*
+ * SETCLIENTID just did a callback update with the callback ident in
+ * "drop," but server trunking discovery claims "drop" and "keep" are
+ * actually the same server.  Swap the callback IDs so that "keep"
+ * will continue to use the callback ident the server now knows about,
+ * and so that "keep"'s original callback ident is destroyed when
+ * "drop" is freed.
+ */
+static void nfs4_swap_callback_idents(struct nfs_client *keep,
+				      struct nfs_client *drop)
+{
+	struct nfs_net *nn = net_generic(keep->cl_net, nfs_net_id);
+	unsigned int save = keep->cl_cb_ident;
+
+	if (keep->cl_cb_ident == drop->cl_cb_ident)
+		return;
+
+	dprintk("%s: keeping callback ident %u and dropping ident %u\n",
+		__func__, keep->cl_cb_ident, drop->cl_cb_ident);
+
+	spin_lock(&nn->nfs_client_lock);
+
+	idr_replace(&nn->cb_ident_idr, keep, drop->cl_cb_ident);
+	keep->cl_cb_ident = drop->cl_cb_ident;
+
+	idr_replace(&nn->cb_ident_idr, drop, save);
+	drop->cl_cb_ident = save;
+
+	spin_unlock(&nn->nfs_client_lock);
+}
+
+static bool nfs4_match_client_owner_id(const struct nfs_client *clp1,
+		const struct nfs_client *clp2)
+{
+	if (clp1->cl_owner_id == NULL || clp2->cl_owner_id == NULL)
+		return true;
+	return strcmp(clp1->cl_owner_id, clp2->cl_owner_id) == 0;
+}
+
+static bool nfs4_same_verifier(nfs4_verifier *v1, nfs4_verifier *v2)
+{
+	return memcmp(v1->data, v2->data, sizeof(v1->data)) == 0;
+}
+
+static int nfs4_match_client(struct nfs_client  *pos,  struct nfs_client *new,
+			     struct nfs_client **prev, struct nfs_net *nn)
+{
+	int status;
+
+	if (pos->rpc_ops != new->rpc_ops)
+		return 1;
+
+	if (pos->cl_minorversion != new->cl_minorversion)
+		return 1;
+
+	/* If "pos" isn't marked ready, we can't trust the
+	 * remaining fields in "pos", especially the client
+	 * ID and serverowner fields.  Wait for CREATE_SESSION
+	 * to finish. */
+	if (pos->cl_cons_state > NFS_CS_READY) {
+		refcount_inc(&pos->cl_count);
+		spin_unlock(&nn->nfs_client_lock);
+
+		nfs_put_client(*prev);
+		*prev = pos;
+
+		status = nfs_wait_client_init_complete(pos);
+		spin_lock(&nn->nfs_client_lock);
+
+		if (status < 0)
+			return status;
+	}
+
+	if (pos->cl_cons_state != NFS_CS_READY)
+		return 1;
+
+	if (pos->cl_clientid != new->cl_clientid)
+		return 1;
+
+	/* NFSv4.1 always uses the uniform string, however someone
+	 * might switch the uniquifier string on us.
+	 */
+	if (!nfs4_match_client_owner_id(pos, new))
+		return 1;
+
+	return 0;
+}
+
+/**
+ * nfs40_walk_client_list - Find server that recognizes a client ID
+ *
+ * @new: nfs_client with client ID to test
+ * @result: OUT: found nfs_client, or new
+ * @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."
+ *
+ * NB: nfs40_walk_client_list() relies on the new nfs_client being
+ *     the last nfs_client on the list.
+ */
+int nfs40_walk_client_list(struct nfs_client *new,
+			   struct nfs_client **result,
+			   const struct cred *cred)
+{
+	struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
+	struct nfs_client *pos, *prev = NULL;
+	struct nfs4_setclientid_res clid = {
+		.clientid	= new->cl_clientid,
+		.confirm	= new->cl_confirm,
+	};
+	int status = -NFS4ERR_STALE_CLIENTID;
+
+	spin_lock(&nn->nfs_client_lock);
+	list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+		if (pos == new)
+			goto found;
+
+		status = nfs4_match_client(pos, new, &prev, nn);
+		if (status < 0)
+			goto out_unlock;
+		if (status != 0)
+			continue;
+		/*
+		 * We just sent a new SETCLIENTID, which should have
+		 * caused the server to return a new cl_confirm.  So if
+		 * cl_confirm is the same, then this is a different
+		 * server that just returned the same cl_confirm by
+		 * coincidence:
+		 */
+		if ((new != pos) && nfs4_same_verifier(&pos->cl_confirm,
+						       &new->cl_confirm))
+			continue;
+		/*
+		 * But if the cl_confirm's are different, then the only
+		 * way that a SETCLIENTID_CONFIRM to pos can succeed is
+		 * if new and pos point to the same server:
+		 */
+found:
+		refcount_inc(&pos->cl_count);
+		spin_unlock(&nn->nfs_client_lock);
+
+		nfs_put_client(prev);
+		prev = pos;
+
+		status = nfs4_proc_setclientid_confirm(pos, &clid, cred);
+		switch (status) {
+		case -NFS4ERR_STALE_CLIENTID:
+			break;
+		case 0:
+			nfs4_swap_callback_idents(pos, new);
+			pos->cl_confirm = new->cl_confirm;
+			nfs_mark_client_ready(pos, NFS_CS_READY);
+
+			prev = NULL;
+			*result = pos;
+			goto out;
+		case -ERESTARTSYS:
+		case -ETIMEDOUT:
+			/* The callback path may have been inadvertently
+			 * changed. Schedule recovery!
+			 */
+			nfs4_schedule_path_down_recovery(pos);
+			goto out;
+		default:
+			goto out;
+		}
+
+		spin_lock(&nn->nfs_client_lock);
+	}
+out_unlock:
+	spin_unlock(&nn->nfs_client_lock);
+
+	/* No match found. The server lost our clientid */
+out:
+	nfs_put_client(prev);
+	return status;
+}
+
+#ifdef CONFIG_NFS_V4_1
+/*
+ * Returns true if the server major ids match
+ */
+bool
+nfs4_check_serverowner_major_id(struct nfs41_server_owner *o1,
+				struct nfs41_server_owner *o2)
+{
+	if (o1->major_id_sz != o2->major_id_sz)
+		return false;
+	return memcmp(o1->major_id, o2->major_id, o1->major_id_sz) == 0;
+}
+
+/*
+ * Returns true if the server scopes match
+ */
+static bool
+nfs4_check_server_scope(struct nfs41_server_scope *s1,
+			struct nfs41_server_scope *s2)
+{
+	if (s1->server_scope_sz != s2->server_scope_sz)
+		return false;
+	return memcmp(s1->server_scope, s2->server_scope,
+					s1->server_scope_sz) == 0;
+}
+
+/**
+ * nfs4_detect_session_trunking - Checks for session trunking.
+ * @clp:    original mount nfs_client
+ * @res:    result structure from an exchange_id using the original mount
+ *          nfs_client with a new multi_addr transport
+ * @xprt:   pointer to the transport to add.
+ *
+ * Called after a successful EXCHANGE_ID on a multi-addr connection.
+ * Upon success, add the transport.
+ *
+ * Returns zero on success, otherwise -EINVAL
+ *
+ * Note: since the exchange_id for the new multi_addr transport uses the
+ * same nfs_client from the original mount, the cl_owner_id is reused,
+ * so eir_clientowner is the same.
+ */
+int nfs4_detect_session_trunking(struct nfs_client *clp,
+				 struct nfs41_exchange_id_res *res,
+				 struct rpc_xprt *xprt)
+{
+	/* Check eir_clientid */
+	if (clp->cl_clientid != res->clientid)
+		goto out_err;
+
+	/* Check eir_server_owner so_major_id */
+	if (!nfs4_check_serverowner_major_id(clp->cl_serverowner,
+					     res->server_owner))
+		goto out_err;
+
+	/* Check eir_server_owner so_minor_id */
+	if (clp->cl_serverowner->minor_id != res->server_owner->minor_id)
+		goto out_err;
+
+	/* Check eir_server_scope */
+	if (!nfs4_check_server_scope(clp->cl_serverscope, res->server_scope))
+		goto out_err;
+
+	pr_info("NFS:  %s: Session trunking succeeded for %s\n",
+		clp->cl_hostname,
+		xprt->address_strings[RPC_DISPLAY_ADDR]);
+
+	return 0;
+out_err:
+	pr_info("NFS:  %s: Session trunking failed for %s\n", clp->cl_hostname,
+		xprt->address_strings[RPC_DISPLAY_ADDR]);
+
+	return -EINVAL;
+}
+
+/**
+ * nfs41_walk_client_list - Find nfs_client that matches a client/server owner
+ *
+ * @new: nfs_client with client ID to test
+ * @result: OUT: found nfs_client, or new
+ * @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."
+ *
+ * NB: nfs41_walk_client_list() relies on the new nfs_client being
+ *     the last nfs_client on the list.
+ */
+int nfs41_walk_client_list(struct nfs_client *new,
+			   struct nfs_client **result,
+			   const struct cred *cred)
+{
+	struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
+	struct nfs_client *pos, *prev = NULL;
+	int status = -NFS4ERR_STALE_CLIENTID;
+
+	spin_lock(&nn->nfs_client_lock);
+	list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+		if (pos == new)
+			goto found;
+
+		status = nfs4_match_client(pos, new, &prev, nn);
+		if (status < 0)
+			goto out;
+		if (status != 0)
+			continue;
+
+		/*
+		 * Note that session trunking is just a special subcase of
+		 * client id trunking. In either case, we want to fall back
+		 * to using the existing nfs_client.
+		 */
+		if (!nfs4_check_serverowner_major_id(pos->cl_serverowner,
+						     new->cl_serverowner))
+			continue;
+
+found:
+		refcount_inc(&pos->cl_count);
+		*result = pos;
+		status = 0;
+		break;
+	}
+
+out:
+	spin_unlock(&nn->nfs_client_lock);
+	nfs_put_client(prev);
+	return status;
+}
+#endif	/* CONFIG_NFS_V4_1 */
+
+static void nfs4_destroy_server(struct nfs_server *server)
+{
+	LIST_HEAD(freeme);
+
+	nfs_server_return_all_delegations(server);
+	unset_pnfs_layoutdriver(server);
+	nfs4_purge_state_owners(server, &freeme);
+	nfs4_free_state_owners(&freeme);
+}
+
+/*
+ * NFSv4.0 callback thread helper
+ *
+ * Find a client by callback identifier
+ */
+struct nfs_client *
+nfs4_find_client_ident(struct net *net, int cb_ident)
+{
+	struct nfs_client *clp;
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+	spin_lock(&nn->nfs_client_lock);
+	clp = idr_find(&nn->cb_ident_idr, cb_ident);
+	if (clp)
+		refcount_inc(&clp->cl_count);
+	spin_unlock(&nn->nfs_client_lock);
+	return clp;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+/* Common match routine for v4.0 and v4.1 callback services */
+static bool nfs4_cb_match_client(const struct sockaddr *addr,
+		struct nfs_client *clp, u32 minorversion)
+{
+	struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
+
+	/* Don't match clients that failed to initialise */
+	if (!(clp->cl_cons_state == NFS_CS_READY ||
+	    clp->cl_cons_state == NFS_CS_SESSION_INITING))
+		return false;
+
+	smp_rmb();
+
+	/* Match the version and minorversion */
+	if (clp->rpc_ops->version != 4 ||
+	    clp->cl_minorversion != minorversion)
+		return false;
+
+	/* Match only the IP address, not the port number */
+	return rpc_cmp_addr(addr, clap);
+}
+
+/*
+ * NFSv4.1 callback thread helper
+ * For CB_COMPOUND calls, find a client by IP address, protocol version,
+ * minorversion, and sessionID
+ *
+ * Returns NULL if no such client
+ */
+struct nfs_client *
+nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
+			   struct nfs4_sessionid *sid, u32 minorversion)
+{
+	struct nfs_client *clp;
+	struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+	spin_lock(&nn->nfs_client_lock);
+	list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
+		if (!nfs4_cb_match_client(addr, clp, minorversion))
+			continue;
+
+		if (!nfs4_has_session(clp))
+			continue;
+
+		/* Match sessionid*/
+		if (memcmp(clp->cl_session->sess_id.data,
+		    sid->data, NFS4_MAX_SESSIONID_LEN) != 0)
+			continue;
+
+		refcount_inc(&clp->cl_count);
+		spin_unlock(&nn->nfs_client_lock);
+		return clp;
+	}
+	spin_unlock(&nn->nfs_client_lock);
+	return NULL;
+}
+
+#else /* CONFIG_NFS_V4_1 */
+
+struct nfs_client *
+nfs4_find_client_sessionid(struct net *net, const struct sockaddr *addr,
+			   struct nfs4_sessionid *sid, u32 minorversion)
+{
+	return NULL;
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+/*
+ * Set up an NFS4 client
+ */
+static int nfs4_set_client(struct nfs_server *server,
+		const char *hostname,
+		const struct sockaddr_storage *addr,
+		const size_t addrlen,
+		const char *ip_addr,
+		int proto, const struct rpc_timeout *timeparms,
+		u32 minorversion, unsigned int nconnect,
+		unsigned int max_connect,
+		struct net *net)
+{
+	struct nfs_client_initdata cl_init = {
+		.hostname = hostname,
+		.addr = addr,
+		.addrlen = addrlen,
+		.ip_addr = ip_addr,
+		.nfs_mod = &nfs_v4,
+		.proto = proto,
+		.minorversion = minorversion,
+		.net = net,
+		.timeparms = timeparms,
+		.cred = server->cred,
+	};
+	struct nfs_client *clp;
+
+	if (minorversion == 0)
+		__set_bit(NFS_CS_REUSEPORT, &cl_init.init_flags);
+	else
+		cl_init.max_connect = max_connect;
+	if (proto == XPRT_TRANSPORT_TCP)
+		cl_init.nconnect = nconnect;
+
+	if (server->flags & NFS_MOUNT_NORESVPORT)
+		__set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
+	if (server->options & NFS_OPTION_MIGRATION)
+		__set_bit(NFS_CS_MIGRATION, &cl_init.init_flags);
+	if (test_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status))
+		__set_bit(NFS_CS_TSM_POSSIBLE, &cl_init.init_flags);
+	server->port = rpc_get_port((struct sockaddr *)addr);
+
+	/* Allocate or find a client reference we can use */
+	clp = nfs_get_client(&cl_init);
+	if (IS_ERR(clp))
+		return PTR_ERR(clp);
+
+	if (server->nfs_client == clp) {
+		nfs_put_client(clp);
+		return -ELOOP;
+	}
+
+	/*
+	 * Query for the lease time on clientid setup or renewal
+	 *
+	 * Note that this will be set on nfs_clients that were created
+	 * only for the DS role and did not set this bit, but now will
+	 * serve a dual role.
+	 */
+	set_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state);
+
+	server->nfs_client = clp;
+	return 0;
+}
+
+/*
+ * Set up a pNFS Data Server client.
+ *
+ * Return any existing nfs_client that matches server address,port,version
+ * and minorversion.
+ *
+ * For a new nfs_client, use a soft mount (default), a low retrans and a
+ * low timeout interval so that if a connection is lost, we retry through
+ * the MDS.
+ */
+struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,
+		const struct sockaddr_storage *ds_addr, int ds_addrlen,
+		int ds_proto, unsigned int ds_timeo, unsigned int ds_retrans,
+		u32 minor_version)
+{
+	struct rpc_timeout ds_timeout;
+	struct nfs_client *mds_clp = mds_srv->nfs_client;
+	struct nfs_client_initdata cl_init = {
+		.addr = ds_addr,
+		.addrlen = ds_addrlen,
+		.nodename = mds_clp->cl_rpcclient->cl_nodename,
+		.ip_addr = mds_clp->cl_ipaddr,
+		.nfs_mod = &nfs_v4,
+		.proto = ds_proto,
+		.minorversion = minor_version,
+		.net = mds_clp->cl_net,
+		.timeparms = &ds_timeout,
+		.cred = mds_srv->cred,
+	};
+	char buf[INET6_ADDRSTRLEN + 1];
+
+	if (rpc_ntop((struct sockaddr *)ds_addr, buf, sizeof(buf)) <= 0)
+		return ERR_PTR(-EINVAL);
+	cl_init.hostname = buf;
+
+	if (mds_clp->cl_nconnect > 1 && ds_proto == XPRT_TRANSPORT_TCP) {
+		cl_init.nconnect = mds_clp->cl_nconnect;
+		cl_init.max_connect = NFS_MAX_TRANSPORTS;
+	}
+
+	if (mds_srv->flags & NFS_MOUNT_NORESVPORT)
+		__set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
+
+	/*
+	 * Set an authflavor equual to the MDS value. Use the MDS nfs_client
+	 * cl_ipaddr so as to use the same EXCHANGE_ID co_ownerid as the MDS
+	 * (section 13.1 RFC 5661).
+	 */
+	nfs_init_timeout_values(&ds_timeout, ds_proto, ds_timeo, ds_retrans);
+	return nfs_get_client(&cl_init);
+}
+EXPORT_SYMBOL_GPL(nfs4_set_ds_client);
+
+/*
+ * Session has been established, and the client marked ready.
+ * Limit the mount rsize, wsize and dtsize using negotiated fore
+ * channel attributes.
+ */
+static void nfs4_session_limit_rwsize(struct nfs_server *server)
+{
+#ifdef CONFIG_NFS_V4_1
+	struct nfs4_session *sess;
+	u32 server_resp_sz;
+	u32 server_rqst_sz;
+
+	if (!nfs4_has_session(server->nfs_client))
+		return;
+	sess = server->nfs_client->cl_session;
+	server_resp_sz = sess->fc_attrs.max_resp_sz - nfs41_maxread_overhead;
+	server_rqst_sz = sess->fc_attrs.max_rqst_sz - nfs41_maxwrite_overhead;
+
+	if (server->dtsize > server_resp_sz)
+		server->dtsize = server_resp_sz;
+	if (server->rsize > server_resp_sz)
+		server->rsize = server_resp_sz;
+	if (server->wsize > server_rqst_sz)
+		server->wsize = server_rqst_sz;
+#endif /* CONFIG_NFS_V4_1 */
+}
+
+/*
+ * Limit xattr sizes using the channel attributes.
+ */
+static void nfs4_session_limit_xasize(struct nfs_server *server)
+{
+#ifdef CONFIG_NFS_V4_2
+	struct nfs4_session *sess;
+	u32 server_gxa_sz;
+	u32 server_sxa_sz;
+	u32 server_lxa_sz;
+
+	if (!nfs4_has_session(server->nfs_client))
+		return;
+
+	sess = server->nfs_client->cl_session;
+
+	server_gxa_sz = sess->fc_attrs.max_resp_sz - nfs42_maxgetxattr_overhead;
+	server_sxa_sz = sess->fc_attrs.max_rqst_sz - nfs42_maxsetxattr_overhead;
+	server_lxa_sz = sess->fc_attrs.max_resp_sz -
+	    nfs42_maxlistxattrs_overhead;
+
+	if (server->gxasize > server_gxa_sz)
+		server->gxasize = server_gxa_sz;
+	if (server->sxasize > server_sxa_sz)
+		server->sxasize = server_sxa_sz;
+	if (server->lxasize > server_lxa_sz)
+		server->lxasize = server_lxa_sz;
+#endif
+}
+
+void nfs4_server_set_init_caps(struct nfs_server *server)
+{
+	/* Set the basic capabilities */
+	server->caps |= server->nfs_client->cl_mvops->init_caps;
+	if (server->flags & NFS_MOUNT_NORDIRPLUS)
+			server->caps &= ~NFS_CAP_READDIRPLUS;
+	if (server->nfs_client->cl_proto == XPRT_TRANSPORT_RDMA)
+		server->caps &= ~NFS_CAP_READ_PLUS;
+
+	/*
+	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
+	 * authentication.
+	 */
+	if (nfs4_disable_idmapping &&
+			server->client->cl_auth->au_flavor == RPC_AUTH_UNIX)
+		server->caps |= NFS_CAP_UIDGID_NOMAP;
+}
+
+static int nfs4_server_common_setup(struct nfs_server *server,
+		struct nfs_fh *mntfh, bool auth_probe)
+{
+	int error;
+
+	/* data servers support only a subset of NFSv4.1 */
+	if (is_ds_only_client(server->nfs_client))
+		return -EPROTONOSUPPORT;
+
+	/* We must ensure the session is initialised first */
+	error = nfs4_init_session(server->nfs_client);
+	if (error < 0)
+		goto out;
+
+	nfs4_server_set_init_caps(server);
+
+	/* Probe the root fh to retrieve its FSID and filehandle */
+	error = nfs4_get_rootfh(server, mntfh, auth_probe);
+	if (error < 0)
+		goto out;
+
+	dprintk("Server FSID: %llx:%llx\n",
+			(unsigned long long) server->fsid.major,
+			(unsigned long long) server->fsid.minor);
+	nfs_display_fhandle(mntfh, "Pseudo-fs root FH");
+
+	error = nfs_probe_server(server, mntfh);
+	if (error < 0)
+		goto out;
+
+	nfs4_session_limit_rwsize(server);
+	nfs4_session_limit_xasize(server);
+
+	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
+		server->namelen = NFS4_MAXNAMLEN;
+
+	nfs_server_insert_lists(server);
+	server->mount_time = jiffies;
+	server->destroy = nfs4_destroy_server;
+out:
+	return error;
+}
+
+/*
+ * Create a version 4 volume record
+ */
+static int nfs4_init_server(struct nfs_server *server, struct fs_context *fc)
+{
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct rpc_timeout timeparms;
+	int error;
+
+	nfs_init_timeout_values(&timeparms, ctx->nfs_server.protocol,
+				ctx->timeo, ctx->retrans);
+
+	/* Initialise the client representation from the mount data */
+	server->flags = ctx->flags;
+	server->options = ctx->options;
+	server->auth_info = ctx->auth_info;
+
+	/* Use the first specified auth flavor. If this flavor isn't
+	 * allowed by the server, use the SECINFO path to try the
+	 * other specified flavors */
+	if (ctx->auth_info.flavor_len >= 1)
+		ctx->selected_flavor = ctx->auth_info.flavors[0];
+	else
+		ctx->selected_flavor = RPC_AUTH_UNIX;
+
+	/* Get a client record */
+	error = nfs4_set_client(server,
+				ctx->nfs_server.hostname,
+				&ctx->nfs_server._address,
+				ctx->nfs_server.addrlen,
+				ctx->client_address,
+				ctx->nfs_server.protocol,
+				&timeparms,
+				ctx->minorversion,
+				ctx->nfs_server.nconnect,
+				ctx->nfs_server.max_connect,
+				fc->net_ns);
+	if (error < 0)
+		return error;
+
+	if (ctx->rsize)
+		server->rsize = nfs_io_size(ctx->rsize, server->nfs_client->cl_proto);
+	if (ctx->wsize)
+		server->wsize = nfs_io_size(ctx->wsize, server->nfs_client->cl_proto);
+
+	server->acregmin = ctx->acregmin * HZ;
+	server->acregmax = ctx->acregmax * HZ;
+	server->acdirmin = ctx->acdirmin * HZ;
+	server->acdirmax = ctx->acdirmax * HZ;
+	server->port     = ctx->nfs_server.port;
+
+	return nfs_init_server_rpcclient(server, &timeparms,
+					 ctx->selected_flavor);
+}
+
+/*
+ * Create a version 4 volume record
+ * - keyed on server and FSID
+ */
+struct nfs_server *nfs4_create_server(struct fs_context *fc)
+{
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct nfs_server *server;
+	bool auth_probe;
+	int error;
+
+	server = nfs_alloc_server();
+	if (!server)
+		return ERR_PTR(-ENOMEM);
+
+	server->cred = get_cred(fc->cred);
+
+	auth_probe = ctx->auth_info.flavor_len < 1;
+
+	/* set up the general RPC client */
+	error = nfs4_init_server(server, fc);
+	if (error < 0)
+		goto error;
+
+	error = nfs4_server_common_setup(server, ctx->mntfh, auth_probe);
+	if (error < 0)
+		goto error;
+
+	return server;
+
+error:
+	nfs_free_server(server);
+	return ERR_PTR(error);
+}
+
+/*
+ * Create an NFS4 referral server record
+ */
+struct nfs_server *nfs4_create_referral_server(struct fs_context *fc)
+{
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct nfs_client *parent_client;
+	struct nfs_server *server, *parent_server;
+	bool auth_probe;
+	int error;
+
+	server = nfs_alloc_server();
+	if (!server)
+		return ERR_PTR(-ENOMEM);
+
+	parent_server = NFS_SB(ctx->clone_data.sb);
+	parent_client = parent_server->nfs_client;
+
+	server->cred = get_cred(parent_server->cred);
+
+	/* Initialise the client representation from the parent server */
+	nfs_server_copy_userdata(server, parent_server);
+
+	/* Get a client representation */
+#if IS_ENABLED(CONFIG_SUNRPC_XPRT_RDMA)
+	rpc_set_port(&ctx->nfs_server.address, NFS_RDMA_PORT);
+	error = nfs4_set_client(server,
+				ctx->nfs_server.hostname,
+				&ctx->nfs_server._address,
+				ctx->nfs_server.addrlen,
+				parent_client->cl_ipaddr,
+				XPRT_TRANSPORT_RDMA,
+				parent_server->client->cl_timeout,
+				parent_client->cl_mvops->minor_version,
+				parent_client->cl_nconnect,
+				parent_client->cl_max_connect,
+				parent_client->cl_net);
+	if (!error)
+		goto init_server;
+#endif	/* IS_ENABLED(CONFIG_SUNRPC_XPRT_RDMA) */
+
+	rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
+	error = nfs4_set_client(server,
+				ctx->nfs_server.hostname,
+				&ctx->nfs_server._address,
+				ctx->nfs_server.addrlen,
+				parent_client->cl_ipaddr,
+				XPRT_TRANSPORT_TCP,
+				parent_server->client->cl_timeout,
+				parent_client->cl_mvops->minor_version,
+				parent_client->cl_nconnect,
+				parent_client->cl_max_connect,
+				parent_client->cl_net);
+	if (error < 0)
+		goto error;
+
+#if IS_ENABLED(CONFIG_SUNRPC_XPRT_RDMA)
+init_server:
+#endif
+	error = nfs_init_server_rpcclient(server, parent_server->client->cl_timeout,
+					  ctx->selected_flavor);
+	if (error < 0)
+		goto error;
+
+	auth_probe = parent_server->auth_info.flavor_len < 1;
+
+	error = nfs4_server_common_setup(server, ctx->mntfh, auth_probe);
+	if (error < 0)
+		goto error;
+
+	return server;
+
+error:
+	nfs_free_server(server);
+	return ERR_PTR(error);
+}
+
+/**
+ * nfs4_update_server - Move an nfs_server to a different nfs_client
+ *
+ * @server: represents FSID to be moved
+ * @hostname: new end-point's hostname
+ * @sap: new end-point's socket address
+ * @salen: size of "sap"
+ * @net: net namespace
+ *
+ * The nfs_server must be quiescent before this function is invoked.
+ * Either its session is drained (NFSv4.1+), or its transport is
+ * plugged and drained (NFSv4.0).
+ *
+ * Returns zero on success, or a negative errno value.
+ */
+int nfs4_update_server(struct nfs_server *server, const char *hostname,
+		       struct sockaddr_storage *sap, size_t salen, struct net *net)
+{
+	struct nfs_client *clp = server->nfs_client;
+	struct rpc_clnt *clnt = server->client;
+	struct xprt_create xargs = {
+		.ident		= clp->cl_proto,
+		.net		= net,
+		.dstaddr	= (struct sockaddr *)sap,
+		.addrlen	= salen,
+		.servername	= hostname,
+	};
+	char buf[INET6_ADDRSTRLEN + 1];
+	struct sockaddr_storage address;
+	struct sockaddr *localaddr = (struct sockaddr *)&address;
+	int error;
+
+	error = rpc_switch_client_transport(clnt, &xargs, clnt->cl_timeout);
+	if (error != 0)
+		return error;
+
+	error = rpc_localaddr(clnt, localaddr, sizeof(address));
+	if (error != 0)
+		return error;
+
+	if (rpc_ntop(localaddr, buf, sizeof(buf)) == 0)
+		return -EAFNOSUPPORT;
+
+	nfs_server_remove_lists(server);
+	set_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status);
+	error = nfs4_set_client(server, hostname, sap, salen, buf,
+				clp->cl_proto, clnt->cl_timeout,
+				clp->cl_minorversion,
+				clp->cl_nconnect, clp->cl_max_connect, net);
+	clear_bit(NFS_MIG_TSM_POSSIBLE, &server->mig_status);
+	if (error != 0) {
+		nfs_server_insert_lists(server);
+		return error;
+	}
+	nfs_put_client(clp);
+
+	if (server->nfs_client->cl_hostname == NULL) {
+		server->nfs_client->cl_hostname = kstrdup(hostname, GFP_KERNEL);
+		if (server->nfs_client->cl_hostname == NULL)
+			return -ENOMEM;
+	}
+	nfs_server_insert_lists(server);
+
+	return nfs_probe_server(server, NFS_FH(d_inode(server->super->s_root)));
+}