Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-only
/*
 * fs/nfs/nfs4session.c
 *
 * Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
 *
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/bc_xprt.h>
#include <linux/nfs.h>
#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include <linux/module.h>
 
#include "nfs4_fs.h"
#include "internal.h"
#include "nfs4session.h"
#include "callback.h"
 
#define NFSDBG_FACILITY		NFSDBG_STATE
 
static void nfs4_init_slot_table(struct nfs4_slot_table *tbl, const char *queue)
{
<------>tbl->highest_used_slotid = NFS4_NO_SLOT;
<------>spin_lock_init(&tbl->slot_tbl_lock);
<------>rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, queue);
<------>init_waitqueue_head(&tbl->slot_waitq);
<------>init_completion(&tbl->complete);
}
 
/*
 * nfs4_shrink_slot_table - free retired slots from the slot table
 */
static void nfs4_shrink_slot_table(struct nfs4_slot_table  *tbl, u32 newsize)
{
<------>struct nfs4_slot **p;
<------>if (newsize >= tbl->max_slots)
<------><------>return;
 
<------>p = &tbl->slots;
<------>while (newsize--)
<------><------>p = &(*p)->next;
<------>while (*p) {
<------><------>struct nfs4_slot *slot = *p;
 
<------><------>*p = slot->next;
<------><------>kfree(slot);
<------><------>tbl->max_slots--;
<------>}
}
 
/**
 * nfs4_slot_tbl_drain_complete - wake waiters when drain is complete
 * @tbl: controlling slot table
 *
 */
void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl)
{
<------>if (nfs4_slot_tbl_draining(tbl))
<------><------>complete(&tbl->complete);
}
 
/*
 * nfs4_free_slot - free a slot and efficiently update slot table.
 *
 * freeing a slot is trivially done by clearing its respective bit
 * in the bitmap.
 * If the freed slotid equals highest_used_slotid we want to update it
 * so that the server would be able to size down the slot table if needed,
 * otherwise we know that the highest_used_slotid is still in use.
 * When updating highest_used_slotid there may be "holes" in the bitmap
 * so we need to scan down from highest_used_slotid to 0 looking for the now
 * highest slotid in use.
 * If none found, highest_used_slotid is set to NFS4_NO_SLOT.
 *
 * Must be called while holding tbl->slot_tbl_lock
 */
void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
{
<------>u32 slotid = slot->slot_nr;
 
<------>/* clear used bit in bitmap */
<------>__clear_bit(slotid, tbl->used_slots);
 
<------>/* update highest_used_slotid when it is freed */
<------>if (slotid == tbl->highest_used_slotid) {
<------><------>u32 new_max = find_last_bit(tbl->used_slots, slotid);
<------><------>if (new_max < slotid)
<------><------><------>tbl->highest_used_slotid = new_max;
<------><------>else {
<------><------><------>tbl->highest_used_slotid = NFS4_NO_SLOT;
<------><------><------>nfs4_slot_tbl_drain_complete(tbl);
<------><------>}
<------>}
<------>dprintk("%s: slotid %u highest_used_slotid %u\n", __func__,
<------><------>slotid, tbl->highest_used_slotid);
}
 
static struct nfs4_slot *nfs4_new_slot(struct nfs4_slot_table  *tbl,
<------><------>u32 slotid, u32 seq_init, gfp_t gfp_mask)
{
<------>struct nfs4_slot *slot;
 
<------>slot = kzalloc(sizeof(*slot), gfp_mask);
<------>if (slot) {
<------><------>slot->table = tbl;
<------><------>slot->slot_nr = slotid;
<------><------>slot->seq_nr = seq_init;
<------><------>slot->seq_nr_highest_sent = seq_init;
<------><------>slot->seq_nr_last_acked = seq_init - 1;
<------>}
<------>return slot;
}
 
static struct nfs4_slot *nfs4_find_or_create_slot(struct nfs4_slot_table  *tbl,
<------><------>u32 slotid, u32 seq_init, gfp_t gfp_mask)
{
<------>struct nfs4_slot **p, *slot;
 
<------>p = &tbl->slots;
<------>for (;;) {
<------><------>if (*p == NULL) {
<------><------><------>*p = nfs4_new_slot(tbl, tbl->max_slots,
<------><------><------><------><------>seq_init, gfp_mask);
<------><------><------>if (*p == NULL)
<------><------><------><------>break;
<------><------><------>tbl->max_slots++;
<------><------>}
<------><------>slot = *p;
<------><------>if (slot->slot_nr == slotid)
<------><------><------>return slot;
<------><------>p = &slot->next;
<------>}
<------>return ERR_PTR(-ENOMEM);
}
 
static void nfs4_lock_slot(struct nfs4_slot_table *tbl,
<------><------>struct nfs4_slot *slot)
{
<------>u32 slotid = slot->slot_nr;
 
<------>__set_bit(slotid, tbl->used_slots);
<------>if (slotid > tbl->highest_used_slotid ||
<------>    tbl->highest_used_slotid == NFS4_NO_SLOT)
<------><------>tbl->highest_used_slotid = slotid;
<------>slot->generation = tbl->generation;
}
 
/*
 * nfs4_try_to_lock_slot - Given a slot try to allocate it
 *
 * Note: must be called with the slot_tbl_lock held.
 */
bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
{
<------>if (nfs4_test_locked_slot(tbl, slot->slot_nr))
<------><------>return false;
<------>nfs4_lock_slot(tbl, slot);
<------>return true;
}
 
/*
 * nfs4_lookup_slot - Find a slot but don't allocate it
 *
 * Note: must be called with the slot_tbl_lock held.
 */
struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid)
{
<------>if (slotid <= tbl->max_slotid)
<------><------>return nfs4_find_or_create_slot(tbl, slotid, 0, GFP_NOWAIT);
<------>return ERR_PTR(-E2BIG);
}
 
static int nfs4_slot_get_seqid(struct nfs4_slot_table  *tbl, u32 slotid,
<------><------>u32 *seq_nr)
<------>__must_hold(&tbl->slot_tbl_lock)
{
<------>struct nfs4_slot *slot;
<------>int ret;
 
<------>slot = nfs4_lookup_slot(tbl, slotid);
<------>ret = PTR_ERR_OR_ZERO(slot);
<------>if (!ret)
<------><------>*seq_nr = slot->seq_nr;
 
<------>return ret;
}
 
/*
 * nfs4_slot_seqid_in_use - test if a slot sequence id is still in use
 *
 * Given a slot table, slot id and sequence number, determine if the
 * RPC call in question is still in flight. This function is mainly
 * intended for use by the callback channel.
 */
static bool nfs4_slot_seqid_in_use(struct nfs4_slot_table *tbl,
<------><------>u32 slotid, u32 seq_nr)
{
<------>u32 cur_seq = 0;
<------>bool ret = false;
 
<------>spin_lock(&tbl->slot_tbl_lock);
<------>if (nfs4_slot_get_seqid(tbl, slotid, &cur_seq) == 0 &&
<------>    cur_seq == seq_nr && test_bit(slotid, tbl->used_slots))
<------><------>ret = true;
<------>spin_unlock(&tbl->slot_tbl_lock);
<------>return ret;
}
 
/*
 * nfs4_slot_wait_on_seqid - wait until a slot sequence id is complete
 *
 * Given a slot table, slot id and sequence number, wait until the
 * corresponding RPC call completes. This function is mainly
 * intended for use by the callback channel.
 */
int nfs4_slot_wait_on_seqid(struct nfs4_slot_table *tbl,
<------><------>u32 slotid, u32 seq_nr,
<------><------>unsigned long timeout)
{
<------>if (wait_event_timeout(tbl->slot_waitq,
<------><------><------>!nfs4_slot_seqid_in_use(tbl, slotid, seq_nr),
<------><------><------>timeout) == 0)
<------><------>return -ETIMEDOUT;
<------>return 0;
}
 
/*
 * nfs4_alloc_slot - efficiently look for a free slot
 *
 * nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
 * If found, we mark the slot as used, update the highest_used_slotid,
 * and respectively set up the sequence operation args.
 *
 * Note: must be called with under the slot_tbl_lock.
 */
struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
{
<------>struct nfs4_slot *ret = ERR_PTR(-EBUSY);
<------>u32 slotid;
 
<------>dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
<------><------>__func__, tbl->used_slots[0], tbl->highest_used_slotid,
<------><------>tbl->max_slotid + 1);
<------>slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
<------>if (slotid <= tbl->max_slotid) {
<------><------>ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
<------><------>if (!IS_ERR(ret))
<------><------><------>nfs4_lock_slot(tbl, ret);
<------>}
<------>dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
<------><------>__func__, tbl->used_slots[0], tbl->highest_used_slotid,
<------><------>!IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
<------>return ret;
}
 
static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
<------><------> u32 max_reqs, u32 ivalue)
{
<------>if (max_reqs <= tbl->max_slots)
<------><------>return 0;
<------>if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
<------><------>return 0;
<------>return -ENOMEM;
}
 
static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
<------><------>u32 server_highest_slotid,
<------><------>u32 ivalue)
{
<------>struct nfs4_slot **p;
 
<------>nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
<------>p = &tbl->slots;
<------>while (*p) {
<------><------>(*p)->seq_nr = ivalue;
<------><------>(*p)->seq_nr_highest_sent = ivalue;
<------><------>(*p)->seq_nr_last_acked = ivalue - 1;
<------><------>p = &(*p)->next;
<------>}
<------>tbl->highest_used_slotid = NFS4_NO_SLOT;
<------>tbl->target_highest_slotid = server_highest_slotid;
<------>tbl->server_highest_slotid = server_highest_slotid;
<------>tbl->d_target_highest_slotid = 0;
<------>tbl->d2_target_highest_slotid = 0;
<------>tbl->max_slotid = server_highest_slotid;
}
 
/*
 * (re)Initialise a slot table
 */
static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
<------><------>u32 max_reqs, u32 ivalue)
{
<------>int ret;
 
<------>dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
<------><------>max_reqs, tbl->max_slots);
 
<------>if (max_reqs > NFS4_MAX_SLOT_TABLE)
<------><------>max_reqs = NFS4_MAX_SLOT_TABLE;
 
<------>ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
<------>if (ret)
<------><------>goto out;
 
<------>spin_lock(&tbl->slot_tbl_lock);
<------>nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
<------>spin_unlock(&tbl->slot_tbl_lock);
 
<------>dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
<------><------>tbl, tbl->slots, tbl->max_slots);
out:
<------>dprintk("<-- %s: return %d\n", __func__, ret);
<------>return ret;
}
 
/*
 * nfs4_release_slot_table - release all slot table entries
 */
static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
{
<------>nfs4_shrink_slot_table(tbl, 0);
}
 
/**
 * nfs4_shutdown_slot_table - release resources attached to a slot table
 * @tbl: slot table to shut down
 *
 */
void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
{
<------>nfs4_release_slot_table(tbl);
<------>rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
}
 
/**
 * nfs4_setup_slot_table - prepare a stand-alone slot table for use
 * @tbl: slot table to set up
 * @max_reqs: maximum number of requests allowed
 * @queue: name to give RPC wait queue
 *
 * Returns zero on success, or a negative errno.
 */
int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
<------><------>const char *queue)
{
<------>nfs4_init_slot_table(tbl, queue);
<------>return nfs4_realloc_slot_table(tbl, max_reqs, 0);
}
 
static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
{
<------>struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
<------>struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
<------>struct nfs4_slot *slot = pslot;
<------>struct nfs4_slot_table *tbl = slot->table;
 
<------>if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
<------><------>return false;
<------>slot->generation = tbl->generation;
<------>args->sa_slot = slot;
<------>res->sr_timestamp = jiffies;
<------>res->sr_slot = slot;
<------>res->sr_status_flags = 0;
<------>res->sr_status = 1;
<------>return true;
}
 
static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
<------><------>struct nfs4_slot *slot)
{
<------>if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
<------><------>return true;
<------>return false;
}
 
bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
<------><------>struct nfs4_slot *slot)
{
<------>if (slot->slot_nr > tbl->max_slotid)
<------><------>return false;
<------>return __nfs41_wake_and_assign_slot(tbl, slot);
}
 
static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
{
<------>struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
<------>if (!IS_ERR(slot)) {
<------><------>bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
<------><------>if (ret)
<------><------><------>return ret;
<------><------>nfs4_free_slot(tbl, slot);
<------>}
<------>return false;
}
 
void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
{
<------>for (;;) {
<------><------>if (!nfs41_try_wake_next_slot_table_entry(tbl))
<------><------><------>break;
<------>}
}
 
#if defined(CONFIG_NFS_V4_1)
 
static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
<------><------>u32 target_highest_slotid)
{
<------>u32 max_slotid;
 
<------>max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
<------>if (max_slotid > tbl->server_highest_slotid)
<------><------>max_slotid = tbl->server_highest_slotid;
<------>if (max_slotid > tbl->target_highest_slotid)
<------><------>max_slotid = tbl->target_highest_slotid;
<------>tbl->max_slotid = max_slotid;
<------>nfs41_wake_slot_table(tbl);
}
 
/* Update the client's idea of target_highest_slotid */
static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
<------><------>u32 target_highest_slotid)
{
<------>if (tbl->target_highest_slotid == target_highest_slotid)
<------><------>return;
<------>tbl->target_highest_slotid = target_highest_slotid;
<------>tbl->generation++;
}
 
void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
<------><------>u32 target_highest_slotid)
{
<------>spin_lock(&tbl->slot_tbl_lock);
<------>nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
<------>tbl->d_target_highest_slotid = 0;
<------>tbl->d2_target_highest_slotid = 0;
<------>nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
<------>spin_unlock(&tbl->slot_tbl_lock);
}
 
static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
<------><------>u32 highest_slotid)
{
<------>if (tbl->server_highest_slotid == highest_slotid)
<------><------>return;
<------>if (tbl->highest_used_slotid > highest_slotid)
<------><------>return;
<------>/* Deallocate slots */
<------>nfs4_shrink_slot_table(tbl, highest_slotid + 1);
<------>tbl->server_highest_slotid = highest_slotid;
}
 
static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
{
<------>s1 -= s2;
<------>if (s1 == 0)
<------><------>return 0;
<------>if (s1 < 0)
<------><------>return (s1 - 1) >> 1;
<------>return (s1 + 1) >> 1;
}
 
static int nfs41_sign_s32(s32 s1)
{
<------>if (s1 > 0)
<------><------>return 1;
<------>if (s1 < 0)
<------><------>return -1;
<------>return 0;
}
 
static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
{
<------>if (!s1 || !s2)
<------><------>return true;
<------>return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
}
 
/* Try to eliminate outliers by checking for sharp changes in the
 * derivatives and second derivatives
 */
static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
<------><------>u32 new_target)
{
<------>s32 d_target, d2_target;
<------>bool ret = true;
 
<------>d_target = nfs41_derivative_target_slotid(new_target,
<------><------><------>tbl->target_highest_slotid);
<------>d2_target = nfs41_derivative_target_slotid(d_target,
<------><------><------>tbl->d_target_highest_slotid);
<------>/* Is first derivative same sign? */
<------>if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
<------><------>ret = false;
<------>/* Is second derivative same sign? */
<------>if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
<------><------>ret = false;
<------>tbl->d_target_highest_slotid = d_target;
<------>tbl->d2_target_highest_slotid = d2_target;
<------>return ret;
}
 
void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
<------><------>struct nfs4_slot *slot,
<------><------>struct nfs4_sequence_res *res)
{
<------>spin_lock(&tbl->slot_tbl_lock);
<------>if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
<------><------>nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
<------>if (tbl->generation == slot->generation)
<------><------>nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
<------>nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
<------>spin_unlock(&tbl->slot_tbl_lock);
}
 
static void nfs4_release_session_slot_tables(struct nfs4_session *session)
{
<------>nfs4_release_slot_table(&session->fc_slot_table);
<------>nfs4_release_slot_table(&session->bc_slot_table);
}
 
/*
 * Initialize or reset the forechannel and backchannel tables
 */
int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
{
<------>struct nfs4_slot_table *tbl;
<------>int status;
 
<------>dprintk("--> %s\n", __func__);
<------>/* Fore channel */
<------>tbl = &ses->fc_slot_table;
<------>tbl->session = ses;
<------>status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
<------>if (status || !(ses->flags & SESSION4_BACK_CHAN)) /* -ENOMEM */
<------><------>return status;
<------>/* Back channel */
<------>tbl = &ses->bc_slot_table;
<------>tbl->session = ses;
<------>status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
<------>if (status && tbl->slots == NULL)
<------><------>/* Fore and back channel share a connection so get
<------><------> * both slot tables or neither */
<------><------>nfs4_release_session_slot_tables(ses);
<------>return status;
}
 
struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
{
<------>struct nfs4_session *session;
 
<------>session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
<------>if (!session)
<------><------>return NULL;
 
<------>nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
<------>nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
<------>session->session_state = 1<<NFS4_SESSION_INITING;
 
<------>session->clp = clp;
<------>return session;
}
 
static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
{
<------>nfs4_shutdown_slot_table(&session->fc_slot_table);
<------>nfs4_shutdown_slot_table(&session->bc_slot_table);
}
 
void nfs4_destroy_session(struct nfs4_session *session)
{
<------>struct rpc_xprt *xprt;
<------>const struct cred *cred;
 
<------>cred = nfs4_get_clid_cred(session->clp);
<------>nfs4_proc_destroy_session(session, cred);
<------>put_cred(cred);
 
<------>rcu_read_lock();
<------>xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
<------>rcu_read_unlock();
<------>dprintk("%s Destroy backchannel for xprt %p\n",
<------><------>__func__, xprt);
<------>xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
<------>nfs4_destroy_session_slot_tables(session);
<------>kfree(session);
}
 
/*
 * With sessions, the client is not marked ready until after a
 * successful EXCHANGE_ID and CREATE_SESSION.
 *
 * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
 * other versions of NFS can be tried.
 */
static int nfs41_check_session_ready(struct nfs_client *clp)
{
<------>int ret;
<------>
<------>if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
<------><------>ret = nfs4_client_recover_expired_lease(clp);
<------><------>if (ret)
<------><------><------>return ret;
<------>}
<------>if (clp->cl_cons_state < NFS_CS_READY)
<------><------>return -EPROTONOSUPPORT;
<------>smp_rmb();
<------>return 0;
}
 
int nfs4_init_session(struct nfs_client *clp)
{
<------>if (!nfs4_has_session(clp))
<------><------>return 0;
 
<------>clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
<------>return nfs41_check_session_ready(clp);
}
 
int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
{
<------>struct nfs4_session *session = clp->cl_session;
<------>int ret;
 
<------>spin_lock(&clp->cl_lock);
<------>if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
<------><------>/*
<------><------> * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
<------><------> * DS lease to be equal to the MDS lease.
<------><------> */
<------><------>clp->cl_lease_time = lease_time;
<------><------>clp->cl_last_renewal = jiffies;
<------>}
<------>spin_unlock(&clp->cl_lock);
 
<------>ret = nfs41_check_session_ready(clp);
<------>if (ret)
<------><------>return ret;
<------>/* Test for the DS role */
<------>if (!is_ds_client(clp))
<------><------>return -ENODEV;
<------>return 0;
}
EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
 
#endif	/* defined(CONFIG_NFS_V4_1) */