/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/ptlrpc/ptlrpcd.c
 */

/** \defgroup ptlrpcd PortalRPC daemon
 *
 * ptlrpcd is a special thread with its own set where other user might add
 * requests when they don't want to wait for their completion.
 * PtlRPCD will take care of sending such requests and then processing their
 * replies and calling completion callbacks as necessary.
 * The callbacks are called directly from ptlrpcd context.
 * It is important to never significantly block (esp. on RPCs!) within such
 * completion handler or a deadlock might occur where ptlrpcd enters some
 * callback that attempts to send another RPC and wait for it to return,
 * during which time ptlrpcd is completely blocked, so e.g. if import
 * fails, recovery cannot progress because connection requests are also
 * sent by ptlrpcd.
 *
 * @{
 */

#define DEBUG_SUBSYSTEM S_RPC

#include "../../include/linux/libcfs/libcfs.h"

#include "../include/lustre_net.h"
#include "../include/lustre_lib.h"
#include "../include/lustre_ha.h"
#include "../include/obd_class.h"       /* for obd_zombie */
#include "../include/obd_support.h"     /* for OBD_FAIL_CHECK */
#include "../include/cl_object.h"       /* cl_env_{get,put}() */
#include "../include/lprocfs_status.h"

#include "ptlrpc_internal.h"

/* One of these per CPT. */
struct ptlrpcd {
        int pd_size;
        int pd_index;
        int pd_cpt;
        int pd_cursor;
        int pd_nthreads;
        int pd_groupsize;
        struct ptlrpcd_ctl pd_threads[0];
};

/*
 * max_ptlrpcds is obsolete, but retained to ensure that the kernel
 * module will load on a system where it has been tuned.
 * A value other than 0 implies it was tuned, in which case the value
 * is used to derive a setting for ptlrpcd_per_cpt_max.
 */
static int max_ptlrpcds;
module_param(max_ptlrpcds, int, 0644);
MODULE_PARM_DESC(max_ptlrpcds,
                 "Max ptlrpcd thread count to be started (obsolete).");

/*
 * ptlrpcd_bind_policy is obsolete, but retained to ensure that
 * the kernel module will load on a system where it has been tuned.
 * A value other than 0 implies it was tuned, in which case the value
 * is used to derive a setting for ptlrpcd_partner_group_size.
 */
static int ptlrpcd_bind_policy;
module_param(ptlrpcd_bind_policy, int, 0644);
MODULE_PARM_DESC(ptlrpcd_bind_policy,
                 "Ptlrpcd threads binding mode (obsolete).");

/*
 * ptlrpcd_per_cpt_max: The maximum number of ptlrpcd threads to run
 * in a CPT.
 */
static int ptlrpcd_per_cpt_max;
module_param(ptlrpcd_per_cpt_max, int, 0644);
MODULE_PARM_DESC(ptlrpcd_per_cpt_max,
                 "Max ptlrpcd thread count to be started per CPT.");

/*
 * ptlrpcd_partner_group_size: The desired number of threads in each
 * ptlrpcd partner thread group. Default is 2, corresponding to the
 * old PDB_POLICY_PAIR. A negative value makes all ptlrpcd threads in
 * a CPT partners of each other.
 */
static int ptlrpcd_partner_group_size;
module_param(ptlrpcd_partner_group_size, int, 0644);
MODULE_PARM_DESC(ptlrpcd_partner_group_size,
                 "Number of ptlrpcd threads in a partner group.");

/*
 * ptlrpcd_cpts: A CPT string describing the CPU partitions that
 * ptlrpcd threads should run on. Used to make ptlrpcd threads run on
 * a subset of all CPTs.
 *
 * ptlrpcd_cpts=2
 * ptlrpcd_cpts=[2]
 *   run ptlrpcd threads only on CPT 2.
 *
 * ptlrpcd_cpts=0-3
 * ptlrpcd_cpts=[0-3]
 *   run ptlrpcd threads on CPTs 0, 1, 2, and 3.
 *
 * ptlrpcd_cpts=[0-3,5,7]
 *   run ptlrpcd threads on CPTS 0, 1, 2, 3, 5, and 7.
 */
static char *ptlrpcd_cpts;
module_param(ptlrpcd_cpts, charp, 0644);
MODULE_PARM_DESC(ptlrpcd_cpts,
                 "CPU partitions ptlrpcd threads should run in");

/* ptlrpcds_cpt_idx maps cpt numbers to an index in the ptlrpcds array. */
static int              *ptlrpcds_cpt_idx;

/* ptlrpcds_num is the number of entries in the ptlrpcds array. */
static int              ptlrpcds_num;
static struct ptlrpcd   **ptlrpcds;

/*
 * In addition to the regular thread pool above, there is a single
 * global recovery thread. Recovery isn't critical for performance,
 * and doesn't block, but must always be able to proceed, and it is
 * possible that all normal ptlrpcd threads are blocked. Hence the
 * need for a dedicated thread.
 */
static struct ptlrpcd_ctl ptlrpcd_rcv;

struct mutex ptlrpcd_mutex;
static int ptlrpcd_users;

void ptlrpcd_wake(struct ptlrpc_request *req)
{
        struct ptlrpc_request_set *set = req->rq_set;

        wake_up(&set->set_waitq);
}
EXPORT_SYMBOL(ptlrpcd_wake);

static struct ptlrpcd_ctl *
ptlrpcd_select_pc(struct ptlrpc_request *req)
{
        struct ptlrpcd  *pd;
        int             cpt;
        int             idx;

        if (req && req->rq_send_state != LUSTRE_IMP_FULL)
                return &ptlrpcd_rcv;

        cpt = cfs_cpt_current(cfs_cpt_table, 1);
        if (!ptlrpcds_cpt_idx)
                idx = cpt;
        else
                idx = ptlrpcds_cpt_idx[cpt];
        pd = ptlrpcds[idx];

                /* We do not care whether it is strict load balance. */
        idx = pd->pd_cursor;
        if (++idx == pd->pd_nthreads)
                idx = 0;
        pd->pd_cursor = idx;

        return &pd->pd_threads[idx];
}

/**
 * Return transferred RPCs count.
 */
static int ptlrpcd_steal_rqset(struct ptlrpc_request_set *des,
                               struct ptlrpc_request_set *src)
{
        struct list_head *tmp, *pos;
        struct ptlrpc_request *req;
        int rc = 0;

        spin_lock(&src->set_new_req_lock);
        if (likely(!list_empty(&src->set_new_requests))) {
                list_for_each_safe(pos, tmp, &src->set_new_requests) {
                        req = list_entry(pos, struct ptlrpc_request,
                                         rq_set_chain);
                        req->rq_set = des;
                }
                list_splice_init(&src->set_new_requests, &des->set_requests);
                rc = atomic_read(&src->set_new_count);
                atomic_add(rc, &des->set_remaining);
                atomic_set(&src->set_new_count, 0);
        }
        spin_unlock(&src->set_new_req_lock);
        return rc;
}

/**
 * Requests that are added to the ptlrpcd queue are sent via
 * ptlrpcd_check->ptlrpc_check_set().
 */
void ptlrpcd_add_req(struct ptlrpc_request *req)
{
        struct ptlrpcd_ctl *pc;

        if (req->rq_reqmsg)
                lustre_msg_set_jobid(req->rq_reqmsg, NULL);

        spin_lock(&req->rq_lock);
        if (req->rq_invalid_rqset) {
                struct l_wait_info lwi = LWI_TIMEOUT(cfs_time_seconds(5),
                                                     back_to_sleep, NULL);

                req->rq_invalid_rqset = 0;
                spin_unlock(&req->rq_lock);
                l_wait_event(req->rq_set_waitq, !req->rq_set, &lwi);
        } else if (req->rq_set) {
                /* If we have a valid "rq_set", just reuse it to avoid double
                 * linked.
                 */
                LASSERT(req->rq_phase == RQ_PHASE_NEW);
                LASSERT(req->rq_send_state == LUSTRE_IMP_REPLAY);

                /* ptlrpc_check_set will decrease the count */
                atomic_inc(&req->rq_set->set_remaining);
                spin_unlock(&req->rq_lock);
                wake_up(&req->rq_set->set_waitq);
                return;
        } else {
                spin_unlock(&req->rq_lock);
        }

        pc = ptlrpcd_select_pc(req);

        DEBUG_REQ(D_INFO, req, "add req [%p] to pc [%s:%d]",
                  req, pc->pc_name, pc->pc_index);

        ptlrpc_set_add_new_req(pc, req);
}
EXPORT_SYMBOL(ptlrpcd_add_req);

static inline void ptlrpc_reqset_get(struct ptlrpc_request_set *set)
{
        atomic_inc(&set->set_refcount);
}

/**
 * Check if there is more work to do on ptlrpcd set.
 * Returns 1 if yes.
 */
static int ptlrpcd_check(struct lu_env *env, struct ptlrpcd_ctl *pc)
{
        struct list_head *tmp, *pos;
        struct ptlrpc_request *req;
        struct ptlrpc_request_set *set = pc->pc_set;
        int rc = 0;
        int rc2;

        if (atomic_read(&set->set_new_count)) {
                spin_lock(&set->set_new_req_lock);
                if (likely(!list_empty(&set->set_new_requests))) {
                        list_splice_init(&set->set_new_requests,
                                         &set->set_requests);
                        atomic_add(atomic_read(&set->set_new_count),
                                   &set->set_remaining);
                        atomic_set(&set->set_new_count, 0);
                        /*
                         * Need to calculate its timeout.
                         */
                        rc = 1;
                }
                spin_unlock(&set->set_new_req_lock);
        }

        /* We should call lu_env_refill() before handling new requests to make
         * sure that env key the requests depending on really exists.
         */
        rc2 = lu_env_refill(env);
        if (rc2 != 0) {
                /*
                 * XXX This is very awkward situation, because
                 * execution can neither continue (request
                 * interpreters assume that env is set up), nor repeat
                 * the loop (as this potentially results in a tight
                 * loop of -ENOMEM's).
                 *
                 * Fortunately, refill only ever does something when
                 * new modules are loaded, i.e., early during boot up.
                 */
                CERROR("Failure to refill session: %d\n", rc2);
                return rc;
        }

        if (atomic_read(&set->set_remaining))
                rc |= ptlrpc_check_set(env, set);

        /* NB: ptlrpc_check_set has already moved completed request at the
         * head of seq::set_requests
         */
        list_for_each_safe(pos, tmp, &set->set_requests) {
                req = list_entry(pos, struct ptlrpc_request, rq_set_chain);
                if (req->rq_phase != RQ_PHASE_COMPLETE)
                        break;

                list_del_init(&req->rq_set_chain);
                req->rq_set = NULL;
                ptlrpc_req_finished(req);
        }

        if (rc == 0) {
                /*
                 * If new requests have been added, make sure to wake up.
                 */
                rc = atomic_read(&set->set_new_count);

                /* If we have nothing to do, check whether we can take some
                 * work from our partner threads.
                 */
                if (rc == 0 && pc->pc_npartners > 0) {
                        struct ptlrpcd_ctl *partner;
                        struct ptlrpc_request_set *ps;
                        int first = pc->pc_cursor;

                        do {
                                partner = pc->pc_partners[pc->pc_cursor++];
                                if (pc->pc_cursor >= pc->pc_npartners)
                                        pc->pc_cursor = 0;
                                if (!partner)
                                        continue;

                                spin_lock(&partner->pc_lock);
                                ps = partner->pc_set;
                                if (!ps) {
                                        spin_unlock(&partner->pc_lock);
                                        continue;
                                }

                                ptlrpc_reqset_get(ps);
                                spin_unlock(&partner->pc_lock);

                                if (atomic_read(&ps->set_new_count)) {
                                        rc = ptlrpcd_steal_rqset(set, ps);
                                        if (rc > 0)
                                                CDEBUG(D_RPCTRACE, "transfer %d async RPCs [%d->%d]\n",
                                                       rc, partner->pc_index,
                                                       pc->pc_index);
                                }
                                ptlrpc_reqset_put(ps);
                        } while (rc == 0 && pc->pc_cursor != first);
                }
        }

        return rc;
}

/**
 * Main ptlrpcd thread.
 * ptlrpc's code paths like to execute in process context, so we have this
 * thread which spins on a set which contains the rpcs and sends them.
 *
 */
static int ptlrpcd(void *arg)
{
        struct ptlrpcd_ctl *pc = arg;
        struct ptlrpc_request_set *set;
        struct lu_context ses = { 0 };
        struct lu_env env = { .le_ses = &ses };
        int rc = 0;
        int exit = 0;

        unshare_fs_struct();
        if (cfs_cpt_bind(cfs_cpt_table, pc->pc_cpt) != 0)
                CWARN("Failed to bind %s on CPT %d\n", pc->pc_name, pc->pc_cpt);

        /*
         * Allocate the request set after the thread has been bound
         * above. This is safe because no requests will be queued
         * until all ptlrpcd threads have confirmed that they have
         * successfully started.
         */
        set = ptlrpc_prep_set();
        if (!set) {
                rc = -ENOMEM;
                goto failed;
        }
        spin_lock(&pc->pc_lock);
        pc->pc_set = set;
        spin_unlock(&pc->pc_lock);
        /*
         * XXX So far only "client" ptlrpcd uses an environment. In
         * the future, ptlrpcd thread (or a thread-set) has to given
         * an argument, describing its "scope".
         */
        rc = lu_context_init(&env.le_ctx,
                             LCT_CL_THREAD | LCT_REMEMBER | LCT_NOREF);
        if (rc == 0) {
                rc = lu_context_init(env.le_ses,
                                     LCT_SESSION | LCT_REMEMBER | LCT_NOREF);
                if (rc != 0)
                        lu_context_fini(&env.le_ctx);
        }

        if (rc != 0)
                goto failed;

        complete(&pc->pc_starting);

        /*
         * This mainloop strongly resembles ptlrpc_set_wait() except that our
         * set never completes.  ptlrpcd_check() calls ptlrpc_check_set() when
         * there are requests in the set. New requests come in on the set's
         * new_req_list and ptlrpcd_check() moves them into the set.
         */
        do {
                struct l_wait_info lwi;
                int timeout;

                timeout = ptlrpc_set_next_timeout(set);
                lwi = LWI_TIMEOUT(cfs_time_seconds(timeout ? timeout : 1),
                                  ptlrpc_expired_set, set);

                lu_context_enter(&env.le_ctx);
                lu_context_enter(env.le_ses);
                l_wait_event(set->set_waitq, ptlrpcd_check(&env, pc), &lwi);
                lu_context_exit(&env.le_ctx);
                lu_context_exit(env.le_ses);

                /*
                 * Abort inflight rpcs for forced stop case.
                 */
                if (test_bit(LIOD_STOP, &pc->pc_flags)) {
                        if (test_bit(LIOD_FORCE, &pc->pc_flags))
                                ptlrpc_abort_set(set);
                        exit++;
                }

                /*
                 * Let's make one more loop to make sure that ptlrpcd_check()
                 * copied all raced new rpcs into the set so we can kill them.
                 */
        } while (exit < 2);

        /*
         * Wait for inflight requests to drain.
         */
        if (!list_empty(&set->set_requests))
                ptlrpc_set_wait(set);
        lu_context_fini(&env.le_ctx);
        lu_context_fini(env.le_ses);

        complete(&pc->pc_finishing);

        return 0;
failed:
        pc->pc_error = rc;
        complete(&pc->pc_starting);
        return rc;
}

static void ptlrpcd_ctl_init(struct ptlrpcd_ctl *pc, int index, int cpt)
{
        pc->pc_index = index;
        pc->pc_cpt = cpt;
        init_completion(&pc->pc_starting);
        init_completion(&pc->pc_finishing);
        spin_lock_init(&pc->pc_lock);

        if (index < 0) {
                /* Recovery thread. */
                snprintf(pc->pc_name, sizeof(pc->pc_name), "ptlrpcd_rcv");
        } else {
                /* Regular thread. */
                snprintf(pc->pc_name, sizeof(pc->pc_name),
                         "ptlrpcd_%02d_%02d", cpt, index);
        }
}

/* XXX: We want multiple CPU cores to share the async RPC load. So we
 *      start many ptlrpcd threads. We also want to reduce the ptlrpcd
 *      overhead caused by data transfer cross-CPU cores. So we bind
 *      all ptlrpcd threads to a CPT, in the expectation that CPTs
 *      will be defined in a way that matches these boundaries. Within
 *      a CPT a ptlrpcd thread can be scheduled on any available core.
 *
 *      Each ptlrpcd thread has its own request queue. This can cause
 *      response delay if the thread is already busy. To help with
 *      this we define partner threads: these are other threads bound
 *      to the same CPT which will check for work in each other's
 *      request queues if they have no work to do.
 *
 *      The desired number of partner threads can be tuned by setting
 *      ptlrpcd_partner_group_size. The default is to create pairs of
 *      partner threads.
 */
static int ptlrpcd_partners(struct ptlrpcd *pd, int index)
{
        struct ptlrpcd_ctl *pc;
        struct ptlrpcd_ctl **ppc;
        int first;
        int i;
        int rc = 0;
        int size;

        LASSERT(index >= 0 && index < pd->pd_nthreads);
        pc = &pd->pd_threads[index];
        pc->pc_npartners = pd->pd_groupsize - 1;

        if (pc->pc_npartners <= 0)
                goto out;

        size = sizeof(struct ptlrpcd_ctl *) * pc->pc_npartners;
        pc->pc_partners = kzalloc_node(size, GFP_NOFS,
                                       cfs_cpt_spread_node(cfs_cpt_table,
                                                           pc->pc_cpt));
        if (!pc->pc_partners) {
                pc->pc_npartners = 0;
                rc = -ENOMEM;
                goto out;
        }

        first = index - index % pd->pd_groupsize;
        ppc = pc->pc_partners;
        for (i = first; i < first + pd->pd_groupsize; i++) {
                if (i != index)
                        *ppc++ = &pd->pd_threads[i];
        }
out:
        return rc;
}

int ptlrpcd_start(struct ptlrpcd_ctl *pc)
{
        struct task_struct *task;
        int rc = 0;

        /*
         * Do not allow start second thread for one pc.
         */
        if (test_and_set_bit(LIOD_START, &pc->pc_flags)) {
                CWARN("Starting second thread (%s) for same pc %p\n",
                      pc->pc_name, pc);
                return 0;
        }

        task = kthread_run(ptlrpcd, pc, "%s", pc->pc_name);
        if (IS_ERR(task)) {
                rc = PTR_ERR(task);
                goto out_set;
        }

        wait_for_completion(&pc->pc_starting);
        rc = pc->pc_error;
        if (rc != 0)
                goto out_set;

        return 0;

out_set:
        if (pc->pc_set) {
                struct ptlrpc_request_set *set = pc->pc_set;

                spin_lock(&pc->pc_lock);
                pc->pc_set = NULL;
                spin_unlock(&pc->pc_lock);
                ptlrpc_set_destroy(set);
        }
        clear_bit(LIOD_START, &pc->pc_flags);
        return rc;
}

void ptlrpcd_stop(struct ptlrpcd_ctl *pc, int force)
{
        if (!test_bit(LIOD_START, &pc->pc_flags)) {
                CWARN("Thread for pc %p was not started\n", pc);
                return;
        }

        set_bit(LIOD_STOP, &pc->pc_flags);
        if (force)
                set_bit(LIOD_FORCE, &pc->pc_flags);
        wake_up(&pc->pc_set->set_waitq);
}

void ptlrpcd_free(struct ptlrpcd_ctl *pc)
{
        struct ptlrpc_request_set *set = pc->pc_set;

        if (!test_bit(LIOD_START, &pc->pc_flags)) {
                CWARN("Thread for pc %p was not started\n", pc);
                goto out;
        }

        wait_for_completion(&pc->pc_finishing);

        spin_lock(&pc->pc_lock);
        pc->pc_set = NULL;
        spin_unlock(&pc->pc_lock);
        ptlrpc_set_destroy(set);

        clear_bit(LIOD_START, &pc->pc_flags);
        clear_bit(LIOD_STOP, &pc->pc_flags);
        clear_bit(LIOD_FORCE, &pc->pc_flags);

out:
        if (pc->pc_npartners > 0) {
                LASSERT(pc->pc_partners);

                kfree(pc->pc_partners);
                pc->pc_partners = NULL;
        }
        pc->pc_npartners = 0;
        pc->pc_error = 0;
}

static void ptlrpcd_fini(void)
{
        int i;
        int j;

        if (ptlrpcds) {
                for (i = 0; i < ptlrpcds_num; i++) {
                        if (!ptlrpcds[i])
                                break;
                        for (j = 0; j < ptlrpcds[i]->pd_nthreads; j++)
                                ptlrpcd_stop(&ptlrpcds[i]->pd_threads[j], 0);
                        for (j = 0; j < ptlrpcds[i]->pd_nthreads; j++)
                                ptlrpcd_free(&ptlrpcds[i]->pd_threads[j]);
                        kfree(ptlrpcds[i]);
                        ptlrpcds[i] = NULL;
                }
                kfree(ptlrpcds);
        }
        ptlrpcds_num = 0;

        ptlrpcd_stop(&ptlrpcd_rcv, 0);
        ptlrpcd_free(&ptlrpcd_rcv);

        kfree(ptlrpcds_cpt_idx);
        ptlrpcds_cpt_idx = NULL;
}

static int ptlrpcd_init(void)
{
        int nthreads;
        int groupsize;
        int size;
        int i;
        int j;
        int rc = 0;
        struct cfs_cpt_table *cptable;
        __u32 *cpts = NULL;
        int ncpts;
        int cpt;
        struct ptlrpcd *pd;

        /*
         * Determine the CPTs that ptlrpcd threads will run on.
         */
        cptable = cfs_cpt_table;
        ncpts = cfs_cpt_number(cptable);
        if (ptlrpcd_cpts) {
                struct cfs_expr_list *el;

                size = ncpts * sizeof(ptlrpcds_cpt_idx[0]);
                ptlrpcds_cpt_idx = kzalloc(size, GFP_KERNEL);
                if (!ptlrpcds_cpt_idx) {
                        rc = -ENOMEM;
                        goto out;
                }

                rc = cfs_expr_list_parse(ptlrpcd_cpts,
                                         strlen(ptlrpcd_cpts),
                                         0, ncpts - 1, &el);

                if (rc != 0) {
                        CERROR("ptlrpcd_cpts: invalid CPT pattern string: %s",
                               ptlrpcd_cpts);
                        rc = -EINVAL;
                        goto out;
                }

                rc = cfs_expr_list_values(el, ncpts, &cpts);
                cfs_expr_list_free(el);
                if (rc <= 0) {
                        CERROR("ptlrpcd_cpts: failed to parse CPT array %s: %d\n",
                               ptlrpcd_cpts, rc);
                        if (rc == 0)
                                rc = -EINVAL;
                        goto out;
                }

                /*
                 * Create the cpt-to-index map. When there is no match
                 * in the cpt table, pick a cpt at random. This could
                 * be changed to take the topology of the system into
                 * account.
                 */
                for (cpt = 0; cpt < ncpts; cpt++) {
                        for (i = 0; i < rc; i++)
                                if (cpts[i] == cpt)
                                        break;
                        if (i >= rc)
                                i = cpt % rc;
                        ptlrpcds_cpt_idx[cpt] = i;
                }

                cfs_expr_list_values_free(cpts, rc);
                ncpts = rc;
        }
        ptlrpcds_num = ncpts;

        size = ncpts * sizeof(ptlrpcds[0]);
        ptlrpcds = kzalloc(size, GFP_KERNEL);
        if (!ptlrpcds) {
                rc = -ENOMEM;
                goto out;
        }

        /*
         * The max_ptlrpcds parameter is obsolete, but do something
         * sane if it has been tuned, and complain if
         * ptlrpcd_per_cpt_max has also been tuned.
         */
        if (max_ptlrpcds != 0) {
                CWARN("max_ptlrpcds is obsolete.\n");
                if (ptlrpcd_per_cpt_max == 0) {
                        ptlrpcd_per_cpt_max = max_ptlrpcds / ncpts;
                        /* Round up if there is a remainder. */
                        if (max_ptlrpcds % ncpts != 0)
                                ptlrpcd_per_cpt_max++;
                        CWARN("Setting ptlrpcd_per_cpt_max = %d\n",
                              ptlrpcd_per_cpt_max);
                } else {
                        CWARN("ptlrpd_per_cpt_max is also set!\n");
                }
        }

        /*
         * The ptlrpcd_bind_policy parameter is obsolete, but do
         * something sane if it has been tuned, and complain if
         * ptlrpcd_partner_group_size is also tuned.
         */
        if (ptlrpcd_bind_policy != 0) {
                CWARN("ptlrpcd_bind_policy is obsolete.\n");
                if (ptlrpcd_partner_group_size == 0) {
                        switch (ptlrpcd_bind_policy) {
                        case 1: /* PDB_POLICY_NONE */
                        case 2: /* PDB_POLICY_FULL */
                                ptlrpcd_partner_group_size = 1;
                                break;
                        case 3: /* PDB_POLICY_PAIR */
                                ptlrpcd_partner_group_size = 2;
                                break;
                        case 4: /* PDB_POLICY_NEIGHBOR */
#ifdef CONFIG_NUMA
                                ptlrpcd_partner_group_size = -1; /* CPT */
#else
                                ptlrpcd_partner_group_size = 3; /* Triplets */
#endif
                                break;
                        default: /* Illegal value, use the default. */
                                ptlrpcd_partner_group_size = 2;
                                break;
                        }
                        CWARN("Setting ptlrpcd_partner_group_size = %d\n",
                              ptlrpcd_partner_group_size);
                } else {
                        CWARN("ptlrpcd_partner_group_size is also set!\n");
                }
        }

        if (ptlrpcd_partner_group_size == 0)
                ptlrpcd_partner_group_size = 2;
        else if (ptlrpcd_partner_group_size < 0)
                ptlrpcd_partner_group_size = -1;
        else if (ptlrpcd_per_cpt_max > 0 &&
                 ptlrpcd_partner_group_size > ptlrpcd_per_cpt_max)
                ptlrpcd_partner_group_size = ptlrpcd_per_cpt_max;

        /*
         * Start the recovery thread first.
         */
        set_bit(LIOD_RECOVERY, &ptlrpcd_rcv.pc_flags);
        ptlrpcd_ctl_init(&ptlrpcd_rcv, -1, CFS_CPT_ANY);
        rc = ptlrpcd_start(&ptlrpcd_rcv);
        if (rc < 0)
                goto out;

        for (i = 0; i < ncpts; i++) {
                if (!cpts)
                        cpt = i;
                else
                        cpt = cpts[i];

                nthreads = cfs_cpt_weight(cptable, cpt);
                if (ptlrpcd_per_cpt_max > 0 && ptlrpcd_per_cpt_max < nthreads)
                        nthreads = ptlrpcd_per_cpt_max;
                if (nthreads < 2)
                        nthreads = 2;

                if (ptlrpcd_partner_group_size <= 0) {
                        groupsize = nthreads;
                } else if (nthreads <= ptlrpcd_partner_group_size) {
                        groupsize = nthreads;
                } else {
                        groupsize = ptlrpcd_partner_group_size;
                        if (nthreads % groupsize != 0)
                                nthreads += groupsize - (nthreads % groupsize);
                }

                size = offsetof(struct ptlrpcd, pd_threads[nthreads]);
                pd = kzalloc_node(size, GFP_NOFS,
                                  cfs_cpt_spread_node(cfs_cpt_table, cpt));
                if (!pd) {
                        rc = -ENOMEM;
                        goto out;
                }
                pd->pd_size = size;
                pd->pd_index = i;
                pd->pd_cpt = cpt;
                pd->pd_cursor = 0;
                pd->pd_nthreads = nthreads;
                pd->pd_groupsize = groupsize;
                ptlrpcds[i] = pd;

                /*
                 * The ptlrpcd threads in a partner group can access
                 * each other's struct ptlrpcd_ctl, so these must be
                 * initialized before any thread is started.
                 */
                for (j = 0; j < nthreads; j++) {
                        ptlrpcd_ctl_init(&pd->pd_threads[j], j, cpt);
                        rc = ptlrpcd_partners(pd, j);
                        if (rc < 0)
                                goto out;
                }

                /* XXX: We start nthreads ptlrpc daemons.
                 *      Each of them can process any non-recovery
                 *      async RPC to improve overall async RPC
                 *      efficiency.
                 *
                 *      But there are some issues with async I/O RPCs
                 *      and async non-I/O RPCs processed in the same
                 *      set under some cases. The ptlrpcd may be
                 *      blocked by some async I/O RPC(s), then will
                 *      cause other async non-I/O RPC(s) can not be
                 *      processed in time.
                 *
                 *      Maybe we should distinguish blocked async RPCs
                 *      from non-blocked async RPCs, and process them
                 *      in different ptlrpcd sets to avoid unnecessary
                 *      dependency. But how to distribute async RPCs
                 *      load among all the ptlrpc daemons becomes
                 *      another trouble.
                 */
                for (j = 0; j < nthreads; j++) {
                        rc = ptlrpcd_start(&pd->pd_threads[j]);
                        if (rc < 0)
                                goto out;
                }
        }
out:
        if (rc != 0)
                ptlrpcd_fini();

        return rc;
}

int ptlrpcd_addref(void)
{
        int rc = 0;

        mutex_lock(&ptlrpcd_mutex);
        if (++ptlrpcd_users == 1) {
                rc = ptlrpcd_init();
                if (rc < 0)
                        ptlrpcd_users--;
        }
        mutex_unlock(&ptlrpcd_mutex);
        return rc;
}
EXPORT_SYMBOL(ptlrpcd_addref);

void ptlrpcd_decref(void)
{
        mutex_lock(&ptlrpcd_mutex);
        if (--ptlrpcd_users == 0)
                ptlrpcd_fini();
        mutex_unlock(&ptlrpcd_mutex);
}
EXPORT_SYMBOL(ptlrpcd_decref);
/** @} ptlrpcd */