[mirror_ubuntu-artful-kernel.git] / drivers / staging / lustre / lustre / ptlrpc / ptlrpcd.c

/*
 * 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.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, 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"

struct ptlrpcd {
        int pd_size;
        int pd_index;
        int pd_nthreads;
        struct ptlrpcd_ctl pd_thread_rcv;
        struct ptlrpcd_ctl pd_threads[0];
};

static int max_ptlrpcds;
module_param(max_ptlrpcds, int, 0644);
MODULE_PARM_DESC(max_ptlrpcds, "Max ptlrpcd thread count to be started.");

static int ptlrpcd_bind_policy = PDB_POLICY_PAIR;
module_param(ptlrpcd_bind_policy, int, 0644);
MODULE_PARM_DESC(ptlrpcd_bind_policy, "Ptlrpcd threads binding mode.");
static struct ptlrpcd *ptlrpcds;

struct mutex ptlrpcd_mutex;
static int ptlrpcd_users;

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

        LASSERT(rq_set != NULL);

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

static struct ptlrpcd_ctl *
ptlrpcd_select_pc(struct ptlrpc_request *req, pdl_policy_t policy, int index)
{
        int idx = 0;

        if (req != NULL && req->rq_send_state != LUSTRE_IMP_FULL)
                return &ptlrpcds->pd_thread_rcv;

        switch (policy) {
        case PDL_POLICY_SAME:
                idx = smp_processor_id() % ptlrpcds->pd_nthreads;
                break;
        case PDL_POLICY_LOCAL:
                /* Before CPU partition patches available, process it the same
                 * as "PDL_POLICY_ROUND". */
# ifdef CFS_CPU_MODE_NUMA
# warning "fix this code to use new CPU partition APIs"
# endif
                /* Fall through to PDL_POLICY_ROUND until the CPU
                 * CPU partition patches are available. */
                index = -1;
        case PDL_POLICY_PREFERRED:
                if (index >= 0 && index < num_online_cpus()) {
                        idx = index % ptlrpcds->pd_nthreads;
                        break;
                }
                /* Fall through to PDL_POLICY_ROUND for bad index. */
        default:
                /* Fall through to PDL_POLICY_ROUND for unknown policy. */
        case PDL_POLICY_ROUND:
                /* We do not care whether it is strict load balance. */
                idx = ptlrpcds->pd_index + 1;
                if (idx == smp_processor_id())
                        idx++;
                idx %= ptlrpcds->pd_nthreads;
                ptlrpcds->pd_index = idx;
                break;
        }

        return &ptlrpcds->pd_threads[idx];
}

/**
 * Move all request from an existing request set to the ptlrpcd queue.
 * All requests from the set must be in phase RQ_PHASE_NEW.
 */
void ptlrpcd_add_rqset(struct ptlrpc_request_set *set)
{
        struct list_head *tmp, *pos;
        struct ptlrpcd_ctl *pc;
        struct ptlrpc_request_set *new;
        int count, i;

        pc = ptlrpcd_select_pc(NULL, PDL_POLICY_LOCAL, -1);
        new = pc->pc_set;

        list_for_each_safe(pos, tmp, &set->set_requests) {
                struct ptlrpc_request *req =
                        list_entry(pos, struct ptlrpc_request,
                                       rq_set_chain);

                LASSERT(req->rq_phase == RQ_PHASE_NEW);
                req->rq_set = new;
                req->rq_queued_time = cfs_time_current();
        }

        spin_lock(&new->set_new_req_lock);
        list_splice_init(&set->set_requests, &new->set_new_requests);
        i = atomic_read(&set->set_remaining);
        count = atomic_add_return(i, &new->set_new_count);
        atomic_set(&set->set_remaining, 0);
        spin_unlock(&new->set_new_req_lock);
        if (count == i) {
                wake_up(&new->set_waitq);

                /* XXX: It maybe unnecessary to wakeup all the partners. But to
                 *      guarantee the async RPC can be processed ASAP, we have
                 *      no other better choice. It maybe fixed in future. */
                for (i = 0; i < pc->pc_npartners; i++)
                        wake_up(&pc->pc_partners[i]->pc_set->set_waitq);
        }
}
EXPORT_SYMBOL(ptlrpcd_add_rqset);

/**
 * 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, pdl_policy_t policy, int idx)
{
        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 == NULL), &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, policy, idx);

        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 == NULL)
                                        continue;

                                spin_lock(&partner->pc_lock);
                                ps = partner->pc_set;
                                if (ps == NULL) {
                                        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 = pc->pc_set;
        struct lu_env env = { .le_ses = NULL };
        int rc, exit = 0;

        unshare_fs_struct();
#if defined(CONFIG_SMP)
        if (test_bit(LIOD_BIND, &pc->pc_flags)) {
                int index = pc->pc_index;

                if (index >= 0 && index < num_possible_cpus()) {
                        while (!cpu_online(index)) {
                                if (++index >= num_possible_cpus())
                                        index = 0;
                        }
                        set_cpus_allowed_ptr(current,
                                        cpumask_of_node(cpu_to_node(index)));
                }
        }
#endif
        /*
         * 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);
        complete(&pc->pc_starting);

        if (rc != 0)
                return rc;

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

                /*
                 * 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);

        complete(&pc->pc_finishing);

        return 0;
}

/* 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 ptlrpcd thread to specified
 *      CPU core. But binding all ptlrpcd threads maybe cause response delay
 *      because of some CPU core(s) busy with other loads.
 *
 *      For example: "ls -l", some async RPCs for statahead are assigned to
 *      ptlrpcd_0, and ptlrpcd_0 is bound to CPU_0, but CPU_0 may be quite busy
 *      with other non-ptlrpcd, like "ls -l" itself (we want to the "ls -l"
 *      thread, statahead thread, and ptlrpcd thread can run in parallel), under
 *      such case, the statahead async RPCs can not be processed in time, it is
 *      unexpected. If ptlrpcd_0 can be re-scheduled on other CPU core, it may
 *      be better. But it breaks former data transfer policy.
 *
 *      So we shouldn't be blind for avoiding the data transfer. We make some
 *      compromise: divide the ptlrpcd threads pool into two parts. One part is
 *      for bound mode, each ptlrpcd thread in this part is bound to some CPU
 *      core. The other part is for free mode, all the ptlrpcd threads in the
 *      part can be scheduled on any CPU core. We specify some partnership
 *      between bound mode ptlrpcd thread(s) and free mode ptlrpcd thread(s),
 *      and the async RPC load within the partners are shared.
 *
 *      It can partly avoid data transfer cross-CPU (if the bound mode ptlrpcd
 *      thread can be scheduled in time), and try to guarantee the async RPC
 *      processed ASAP (as long as the free mode ptlrpcd thread can be scheduled
 *      on any CPU core).
 *
 *      As for how to specify the partnership between bound mode ptlrpcd
 *      thread(s) and free mode ptlrpcd thread(s), the simplest way is to use
 *      <free bound> pair. In future, we can specify some more complex
 *      partnership based on the patches for CPU partition. But before such
 *      patches are available, we prefer to use the simplest one.
 */
# ifdef CFS_CPU_MODE_NUMA
# warning "fix ptlrpcd_bind() to use new CPU partition APIs"
# endif
static int ptlrpcd_bind(int index, int max)
{
        struct ptlrpcd_ctl *pc;
        int rc = 0;
#if defined(CONFIG_NUMA)
        cpumask_t mask;
#endif

        LASSERT(index <= max - 1);
        pc = &ptlrpcds->pd_threads[index];
        switch (ptlrpcd_bind_policy) {
        case PDB_POLICY_NONE:
                pc->pc_npartners = -1;
                break;
        case PDB_POLICY_FULL:
                pc->pc_npartners = 0;
                set_bit(LIOD_BIND, &pc->pc_flags);
                break;
        case PDB_POLICY_PAIR:
                LASSERT(max % 2 == 0);
                pc->pc_npartners = 1;
                break;
        case PDB_POLICY_NEIGHBOR:
#if defined(CONFIG_NUMA)
        {
                int i;
                cpumask_copy(&mask, cpumask_of_node(cpu_to_node(index)));
                for (i = max; i < num_online_cpus(); i++)
                        cpumask_clear_cpu(i, &mask);
                pc->pc_npartners = cpumask_weight(&mask) - 1;
                set_bit(LIOD_BIND, &pc->pc_flags);
        }
#else
                LASSERT(max >= 3);
                pc->pc_npartners = 2;
#endif
                break;
        default:
                CERROR("unknown ptlrpcd bind policy %d\n", ptlrpcd_bind_policy);
                rc = -EINVAL;
        }

        if (rc == 0 && pc->pc_npartners > 0) {
                pc->pc_partners = kcalloc(pc->pc_npartners,
                                          sizeof(struct ptlrpcd_ctl *),
                                          GFP_NOFS);
                if (pc->pc_partners == NULL) {
                        pc->pc_npartners = 0;
                        rc = -ENOMEM;
                } else {
                        switch (ptlrpcd_bind_policy) {
                        case PDB_POLICY_PAIR:
                                if (index & 0x1) {
                                        set_bit(LIOD_BIND, &pc->pc_flags);
                                        pc->pc_partners[0] = &ptlrpcds->
                                                pd_threads[index - 1];
                                        ptlrpcds->pd_threads[index - 1].
                                                pc_partners[0] = pc;
                                }
                                break;
                        case PDB_POLICY_NEIGHBOR:
#if defined(CONFIG_NUMA)
                        {
                                struct ptlrpcd_ctl *ppc;
                                int i, pidx;
                                /* partners are cores in the same NUMA node.
                                 * setup partnership only with ptlrpcd threads
                                 * that are already initialized
                                 */
                                for (pidx = 0, i = 0; i < index; i++) {
                                        if (cpumask_test_cpu(i, &mask)) {
                                                ppc = &ptlrpcds->pd_threads[i];
                                                pc->pc_partners[pidx++] = ppc;
                                                ppc->pc_partners[ppc->
                                                          pc_npartners++] = pc;
                                        }
                                }
                                /* adjust number of partners to the number
                                 * of partnership really setup */
                                pc->pc_npartners = pidx;
                        }
#else
                                if (index & 0x1)
                                        set_bit(LIOD_BIND, &pc->pc_flags);
                                if (index > 0) {
                                        pc->pc_partners[0] = &ptlrpcds->
                                                pd_threads[index - 1];
                                        ptlrpcds->pd_threads[index - 1].
                                                pc_partners[1] = pc;
                                        if (index == max - 1) {
                                                pc->pc_partners[1] =
                                                &ptlrpcds->pd_threads[0];
                                                ptlrpcds->pd_threads[0].
                                                pc_partners[0] = pc;
                                        }
                                }
#endif
                                break;
                        }
                }
        }

        return rc;
}


int ptlrpcd_start(int index, int max, const char *name, struct ptlrpcd_ctl *pc)
{
        int rc;

        /*
         * 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",
                      name, pc);
                return 0;
        }

        pc->pc_index = index;
        init_completion(&pc->pc_starting);
        init_completion(&pc->pc_finishing);
        spin_lock_init(&pc->pc_lock);
        strlcpy(pc->pc_name, name, sizeof(pc->pc_name));
        pc->pc_set = ptlrpc_prep_set();
        if (pc->pc_set == NULL) {
                rc = -ENOMEM;
                goto out;
        }

        /*
         * So far only "client" ptlrpcd uses an environment. In the future,
         * ptlrpcd thread (or a thread-set) has to be given an argument,
         * describing its "scope".
         */
        rc = lu_context_init(&pc->pc_env.le_ctx, LCT_CL_THREAD|LCT_REMEMBER);
        if (rc != 0)
                goto out_set;

        {
                struct task_struct *task;
                if (index >= 0) {
                        rc = ptlrpcd_bind(index, max);
                        if (rc < 0)
                                goto out_env;
                }

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

                wait_for_completion(&pc->pc_starting);
        }
        return 0;

out_env:
        lu_context_fini(&pc->pc_env.le_ctx);

out_set:
        if (pc->pc_set != NULL) {
                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_BIND, &pc->pc_flags);

out:
        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);
        lu_context_fini(&pc->pc_env.le_ctx);

        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);
        clear_bit(LIOD_BIND, &pc->pc_flags);

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

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

static void ptlrpcd_fini(void)
{
        int i;

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

static int ptlrpcd_init(void)
{
        int nthreads = num_online_cpus();
        char name[16];
        int size, i = -1, j, rc = 0;

        if (max_ptlrpcds > 0 && max_ptlrpcds < nthreads)
                nthreads = max_ptlrpcds;
        if (nthreads < 2)
                nthreads = 2;
        if (nthreads < 3 && ptlrpcd_bind_policy == PDB_POLICY_NEIGHBOR)
                ptlrpcd_bind_policy = PDB_POLICY_PAIR;
        else if (nthreads % 2 != 0 && ptlrpcd_bind_policy == PDB_POLICY_PAIR)
                nthreads &= ~1; /* make sure it is even */

        size = offsetof(struct ptlrpcd, pd_threads[nthreads]);
        ptlrpcds = kzalloc(size, GFP_NOFS);
        if (ptlrpcds == NULL) {
                rc = -ENOMEM;
                goto out;
        }

        snprintf(name, sizeof(name), "ptlrpcd_rcv");
        set_bit(LIOD_RECOVERY, &ptlrpcds->pd_thread_rcv.pc_flags);
        rc = ptlrpcd_start(-1, nthreads, name, &ptlrpcds->pd_thread_rcv);
        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 (i = 0; i < nthreads; i++) {
                snprintf(name, sizeof(name), "ptlrpcd_%d", i);
                rc = ptlrpcd_start(i, nthreads, name, &ptlrpcds->pd_threads[i]);
                if (rc < 0)
                        goto out;
        }

        ptlrpcds->pd_size = size;
        ptlrpcds->pd_index = 0;
        ptlrpcds->pd_nthreads = nthreads;

out:
        if (rc != 0 && ptlrpcds != NULL) {
                for (j = 0; j <= i; j++)
                        ptlrpcd_stop(&ptlrpcds->pd_threads[j], 0);
                for (j = 0; j <= i; j++)
                        ptlrpcd_free(&ptlrpcds->pd_threads[j]);
                ptlrpcd_stop(&ptlrpcds->pd_thread_rcv, 0);
                ptlrpcd_free(&ptlrpcds->pd_thread_rcv);
                kfree(ptlrpcds);
                ptlrpcds = NULL;
        }

        return 0;
}

int ptlrpcd_addref(void)
{
        int rc = 0;

        mutex_lock(&ptlrpcd_mutex);
        if (++ptlrpcd_users == 1)
                rc = ptlrpcd_init();
        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 */