lustre/ptlrpc/ptlrpcd.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2014, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/ptlrpc/ptlrpcd.c
  37  */
  38
  39 /** \defgroup ptlrpcd PortalRPC daemon
  40  *
  41  * ptlrpcd is a special thread with its own set where other user might add
  42  * requests when they don't want to wait for their completion.
  43  * PtlRPCD will take care of sending such requests and then processing their
  44  * replies and calling completion callbacks as necessary.
  45  * The callbacks are called directly from ptlrpcd context.
  46  * It is important to never significantly block (esp. on RPCs!) within such
  47  * completion handler or a deadlock might occur where ptlrpcd enters some
  48  * callback that attempts to send another RPC and wait for it to return,
  49  * during which time ptlrpcd is completely blocked, so e.g. if import
  50  * fails, recovery cannot progress because connection requests are also
  51  * sent by ptlrpcd.
  52  *
  53  * @{
  54  */
  55
  56 #define DEBUG_SUBSYSTEM S_RPC
  57
  58 #include <libcfs/libcfs.h>
  59 #include <lustre_net.h>
  60 #include <lustre_lib.h>
  61 #include <lustre_ha.h>
  62 #include <obd_class.h>   /* for obd_zombie */
  63 #include <obd_support.h> /* for OBD_FAIL_CHECK */
  64 #include <cl_object.h> /* cl_env_{get,put}() */
  65 #include <lprocfs_status.h>
  66
  67 #include "ptlrpc_internal.h"
  68
  69 struct ptlrpcd {
  70         int                pd_size;
  71         int                pd_index;
  72         int                pd_nthreads;
  73         struct ptlrpcd_ctl pd_thread_rcv;
  74         struct ptlrpcd_ctl pd_threads[0];
  75 };
  76
  77 static int max_ptlrpcds;
  78 CFS_MODULE_PARM(max_ptlrpcds, "i", int, 0644,
  79                 "Max ptlrpcd thread count to be started.");
  80
  81 static int ptlrpcd_bind_policy = PDB_POLICY_PAIR;
  82 CFS_MODULE_PARM(ptlrpcd_bind_policy, "i", int, 0644,
  83                 "Ptlrpcd threads binding mode.");
  84 static struct ptlrpcd *ptlrpcds;
  85
  86 struct mutex ptlrpcd_mutex;
  87 static int ptlrpcd_users = 0;
  88
  89 void ptlrpcd_wake(struct ptlrpc_request *req)
  90 {
  91         struct ptlrpc_request_set *set = req->rq_set;
  92
  93         LASSERT(set != NULL);
  94         wake_up(&set->set_waitq);
  95 }
  96 EXPORT_SYMBOL(ptlrpcd_wake);
  97
  98 static struct ptlrpcd_ctl *
  99 ptlrpcd_select_pc(struct ptlrpc_request *req, pdl_policy_t policy, int index)
 100 {
 101         int idx = 0;
 102
 103         if (req != NULL && req->rq_send_state != LUSTRE_IMP_FULL)
 104                 return &ptlrpcds->pd_thread_rcv;
 105
 106         switch (policy) {
 107         case PDL_POLICY_SAME:
 108                 idx = smp_processor_id() % ptlrpcds->pd_nthreads;
 109                 break;
 110         case PDL_POLICY_LOCAL:
 111                 /* Before CPU partition patches available, process it the same
 112                  * as "PDL_POLICY_ROUND". */
 113 # ifdef CFS_CPU_MODE_NUMA
 114 # warning "fix this code to use new CPU partition APIs"
 115 # endif
 116                 /* Fall through to PDL_POLICY_ROUND until the CPU
 117                  * CPU partition patches are available. */
 118                 index = -1;
 119         case PDL_POLICY_PREFERRED:
 120                 if (index >= 0 && index < num_online_cpus()) {
 121                         idx = index % ptlrpcds->pd_nthreads;
 122                         break;
 123                 }
 124                 /* Fall through to PDL_POLICY_ROUND for bad index. */
 125         default:
 126                 /* Fall through to PDL_POLICY_ROUND for unknown policy. */
 127         case PDL_POLICY_ROUND:
 128                 /* We do not care whether it is strict load balance. */
 129                 idx = ptlrpcds->pd_index + 1;
 130                 if (idx == smp_processor_id())
 131                         idx++;
 132                 idx %= ptlrpcds->pd_nthreads;
 133                 ptlrpcds->pd_index = idx;
 134                 break;
 135         }
 136
 137         return &ptlrpcds->pd_threads[idx];
 138 }
 139
 140 /**
 141  * Move all request from an existing request set to the ptlrpcd queue.
 142  * All requests from the set must be in phase RQ_PHASE_NEW.
 143  */
 144 void ptlrpcd_add_rqset(struct ptlrpc_request_set *set)
 145 {
 146         struct list_head *tmp, *pos;
 147         struct ptlrpcd_ctl *pc;
 148         struct ptlrpc_request_set *new;
 149         int count, i;
 150
 151         pc = ptlrpcd_select_pc(NULL, PDL_POLICY_LOCAL, -1);
 152         new = pc->pc_set;
 153
 154         list_for_each_safe(pos, tmp, &set->set_requests) {
 155                 struct ptlrpc_request *req =
 156                         list_entry(pos, struct ptlrpc_request,
 157                                    rq_set_chain);
 158
 159                 LASSERT(req->rq_phase == RQ_PHASE_NEW);
 160                 req->rq_set = new;
 161                 req->rq_queued_time = cfs_time_current();
 162         }
 163
 164         spin_lock(&new->set_new_req_lock);
 165         list_splice_init(&set->set_requests, &new->set_new_requests);
 166         i = atomic_read(&set->set_remaining);
 167         count = atomic_add_return(i, &new->set_new_count);
 168         atomic_set(&set->set_remaining, 0);
 169         spin_unlock(&new->set_new_req_lock);
 170         if (count == i) {
 171                 wake_up(&new->set_waitq);
 172
 173                 /* XXX: It maybe unnecessary to wakeup all the partners. But to
 174                  *      guarantee the async RPC can be processed ASAP, we have
 175                  *      no other better choice. It maybe fixed in future. */
 176                 for (i = 0; i < pc->pc_npartners; i++)
 177                         wake_up(&pc->pc_partners[i]->pc_set->set_waitq);
 178         }
 179 }
 180
 181 /**
 182  * Return transferred RPCs count.
 183  */
 184 static int ptlrpcd_steal_rqset(struct ptlrpc_request_set *des,
 185                                struct ptlrpc_request_set *src)
 186 {
 187         struct list_head *tmp, *pos;
 188         struct ptlrpc_request *req;
 189         int rc = 0;
 190
 191         spin_lock(&src->set_new_req_lock);
 192         if (likely(!list_empty(&src->set_new_requests))) {
 193                 list_for_each_safe(pos, tmp, &src->set_new_requests) {
 194                         req = list_entry(pos, struct ptlrpc_request,
 195                                          rq_set_chain);
 196                         req->rq_set = des;
 197                 }
 198                 list_splice_init(&src->set_new_requests,
 199                                  &des->set_requests);
 200                 rc = atomic_read(&src->set_new_count);
 201                 atomic_add(rc, &des->set_remaining);
 202                 atomic_set(&src->set_new_count, 0);
 203         }
 204         spin_unlock(&src->set_new_req_lock);
 205         return rc;
 206 }
 207
 208 /**
 209  * Requests that are added to the ptlrpcd queue are sent via
 210  * ptlrpcd_check->ptlrpc_check_set().
 211  */
 212 void ptlrpcd_add_req(struct ptlrpc_request *req, pdl_policy_t policy, int idx)
 213 {
 214         struct ptlrpcd_ctl *pc;
 215
 216         if (req->rq_reqmsg)
 217                 lustre_msg_set_jobid(req->rq_reqmsg, NULL);
 218
 219         spin_lock(&req->rq_lock);
 220         if (req->rq_invalid_rqset) {
 221                 struct l_wait_info lwi = LWI_TIMEOUT(cfs_time_seconds(5),
 222                                                      back_to_sleep, NULL);
 223
 224                 req->rq_invalid_rqset = 0;
 225                 spin_unlock(&req->rq_lock);
 226                 l_wait_event(req->rq_set_waitq, (req->rq_set == NULL), &lwi);
 227         } else if (req->rq_set) {
 228                 /* If we have a vaid "rq_set", just reuse it to avoid double
 229                  * linked. */
 230                 LASSERT(req->rq_phase == RQ_PHASE_NEW);
 231                 LASSERT(req->rq_send_state == LUSTRE_IMP_REPLAY);
 232
 233                 /* ptlrpc_check_set will decrease the count */
 234                 atomic_inc(&req->rq_set->set_remaining);
 235                 spin_unlock(&req->rq_lock);
 236                 wake_up(&req->rq_set->set_waitq);
 237                 return;
 238         } else {
 239                 spin_unlock(&req->rq_lock);
 240         }
 241
 242         pc = ptlrpcd_select_pc(req, policy, idx);
 243
 244         DEBUG_REQ(D_INFO, req, "add req [%p] to pc [%s:%d]",
 245                   req, pc->pc_name, pc->pc_index);
 246
 247         ptlrpc_set_add_new_req(pc, req);
 248 }
 249 EXPORT_SYMBOL(ptlrpcd_add_req);
 250
 251 static inline void ptlrpc_reqset_get(struct ptlrpc_request_set *set)
 252 {
 253         atomic_inc(&set->set_refcount);
 254 }
 255
 256 /**
 257  * Check if there is more work to do on ptlrpcd set.
 258  * Returns 1 if yes.
 259  */
 260 static int ptlrpcd_check(struct lu_env *env, struct ptlrpcd_ctl *pc)
 261 {
 262         struct list_head *tmp, *pos;
 263         struct ptlrpc_request *req;
 264         struct ptlrpc_request_set *set = pc->pc_set;
 265         int rc = 0;
 266         int rc2;
 267         ENTRY;
 268
 269         if (atomic_read(&set->set_new_count)) {
 270                 spin_lock(&set->set_new_req_lock);
 271                 if (likely(!list_empty(&set->set_new_requests))) {
 272                         list_splice_init(&set->set_new_requests,
 273                                              &set->set_requests);
 274                         atomic_add(atomic_read(&set->set_new_count),
 275                                    &set->set_remaining);
 276                         atomic_set(&set->set_new_count, 0);
 277                         /*
 278                          * Need to calculate its timeout.
 279                          */
 280                         rc = 1;
 281                 }
 282                 spin_unlock(&set->set_new_req_lock);
 283         }
 284
 285         /* We should call lu_env_refill() before handling new requests to make
 286          * sure that env key the requests depending on really exists.
 287          */
 288         rc2 = lu_env_refill(env);
 289         if (rc2 != 0) {
 290                 /*
 291                  * XXX This is very awkward situation, because
 292                  * execution can neither continue (request
 293                  * interpreters assume that env is set up), nor repeat
 294                  * the loop (as this potentially results in a tight
 295                  * loop of -ENOMEM's).
 296                  *
 297                  * Fortunately, refill only ever does something when
 298                  * new modules are loaded, i.e., early during boot up.
 299                  */
 300                 CERROR("Failure to refill session: %d\n", rc2);
 301                 RETURN(rc);
 302         }
 303
 304         if (atomic_read(&set->set_remaining))
 305                 rc |= ptlrpc_check_set(env, set);
 306
 307         /* NB: ptlrpc_check_set has already moved complted request at the
 308          * head of seq::set_requests */
 309         list_for_each_safe(pos, tmp, &set->set_requests) {
 310                 req = list_entry(pos, struct ptlrpc_request, rq_set_chain);
 311                 if (req->rq_phase != RQ_PHASE_COMPLETE)
 312                         break;
 313
 314                 list_del_init(&req->rq_set_chain);
 315                 req->rq_set = NULL;
 316                 ptlrpc_req_finished(req);
 317         }
 318
 319         if (rc == 0) {
 320                 /*
 321                  * If new requests have been added, make sure to wake up.
 322                  */
 323                 rc = atomic_read(&set->set_new_count);
 324
 325                 /* If we have nothing to do, check whether we can take some
 326                  * work from our partner threads. */
 327                 if (rc == 0 && pc->pc_npartners > 0) {
 328                         struct ptlrpcd_ctl *partner;
 329                         struct ptlrpc_request_set *ps;
 330                         int first = pc->pc_cursor;
 331
 332                         do {
 333                                 partner = pc->pc_partners[pc->pc_cursor++];
 334                                 if (pc->pc_cursor >= pc->pc_npartners)
 335                                         pc->pc_cursor = 0;
 336                                 if (partner == NULL)
 337                                         continue;
 338
 339                                 spin_lock(&partner->pc_lock);
 340                                 ps = partner->pc_set;
 341                                 if (ps == NULL) {
 342                                         spin_unlock(&partner->pc_lock);
 343                                         continue;
 344                                 }
 345
 346                                 ptlrpc_reqset_get(ps);
 347                                 spin_unlock(&partner->pc_lock);
 348
 349                                 if (atomic_read(&ps->set_new_count)) {
 350                                         rc = ptlrpcd_steal_rqset(set, ps);
 351                                         if (rc > 0)
 352                                                 CDEBUG(D_RPCTRACE, "transfer %d"
 353                                                        " async RPCs [%d->%d]\n",
 354                                                        rc, partner->pc_index,
 355                                                        pc->pc_index);
 356                                 }
 357                                 ptlrpc_reqset_put(ps);
 358                         } while (rc == 0 && pc->pc_cursor != first);
 359                 }
 360         }
 361
 362         RETURN(rc);
 363 }
 364
 365 /**
 366  * Main ptlrpcd thread.
 367  * ptlrpc's code paths like to execute in process context, so we have this
 368  * thread which spins on a set which contains the rpcs and sends them.
 369  *
 370  */
 371 static int ptlrpcd(void *arg)
 372 {
 373         struct ptlrpcd_ctl *pc = arg;
 374         struct ptlrpc_request_set *set = pc->pc_set;
 375         struct lu_context ses = { 0 };
 376         struct lu_env env = { .le_ses = &ses };
 377         int rc, exit = 0;
 378         ENTRY;
 379
 380         unshare_fs_struct();
 381 #if defined(CONFIG_SMP)
 382         if (test_bit(LIOD_BIND, &pc->pc_flags)) {
 383                 int index = pc->pc_index;
 384
 385                 if (index >= 0 && index < num_possible_cpus()) {
 386                         while (!cpu_online(index)) {
 387                                 if (++index >= num_possible_cpus())
 388                                         index = 0;
 389                         }
 390                         set_cpus_allowed_ptr(current,
 391                                      cpumask_of_node(cpu_to_node(index)));
 392                 }
 393         }
 394 #endif
 395         /* Both client and server (MDT/OST) may use the environment. */
 396         rc = lu_context_init(&env.le_ctx, LCT_MD_THREAD | LCT_DT_THREAD |
 397                                           LCT_CL_THREAD | LCT_REMEMBER |
 398                                           LCT_NOREF);
 399         if (rc == 0) {
 400                 rc = lu_context_init(env.le_ses,
 401                                      LCT_SESSION|LCT_REMEMBER|LCT_NOREF);
 402                 if (rc != 0)
 403                         lu_context_fini(&env.le_ctx);
 404         }
 405         complete(&pc->pc_starting);
 406
 407         if (rc != 0)
 408                 RETURN(rc);
 409
 410         /*
 411          * This mainloop strongly resembles ptlrpc_set_wait() except that our
 412          * set never completes.  ptlrpcd_check() calls ptlrpc_check_set() when
 413          * there are requests in the set. New requests come in on the set's
 414          * new_req_list and ptlrpcd_check() moves them into the set.
 415          */
 416         do {
 417                 struct l_wait_info lwi;
 418                 int timeout;
 419
 420                 timeout = ptlrpc_set_next_timeout(set);
 421                 lwi = LWI_TIMEOUT(cfs_time_seconds(timeout ? timeout : 1),
 422                                   ptlrpc_expired_set, set);
 423
 424                 lu_context_enter(&env.le_ctx);
 425                 lu_context_enter(env.le_ses);
 426                 l_wait_event(set->set_waitq, ptlrpcd_check(&env, pc), &lwi);
 427                 lu_context_exit(&env.le_ctx);
 428                 lu_context_exit(env.le_ses);
 429
 430                 /*
 431                  * Abort inflight rpcs for forced stop case.
 432                  */
 433                 if (test_bit(LIOD_STOP, &pc->pc_flags)) {
 434                         if (test_bit(LIOD_FORCE, &pc->pc_flags))
 435                                 ptlrpc_abort_set(set);
 436                         exit++;
 437                 }
 438
 439                 /*
 440                  * Let's make one more loop to make sure that ptlrpcd_check()
 441                  * copied all raced new rpcs into the set so we can kill them.
 442                  */
 443         } while (exit < 2);
 444
 445         /*
 446          * Wait for inflight requests to drain.
 447          */
 448         if (!list_empty(&set->set_requests))
 449                 ptlrpc_set_wait(set);
 450         lu_context_fini(&env.le_ctx);
 451         lu_context_fini(env.le_ses);
 452
 453         complete(&pc->pc_finishing);
 454
 455         return 0;
 456 }
 457
 458 /* XXX: We want multiple CPU cores to share the async RPC load. So we start many
 459  *      ptlrpcd threads. We also want to reduce the ptlrpcd overhead caused by
 460  *      data transfer cross-CPU cores. So we bind ptlrpcd thread to specified
 461  *      CPU core. But binding all ptlrpcd threads maybe cause response delay
 462  *      because of some CPU core(s) busy with other loads.
 463  *
 464  *      For example: "ls -l", some async RPCs for statahead are assigned to
 465  *      ptlrpcd_0, and ptlrpcd_0 is bound to CPU_0, but CPU_0 may be quite busy
 466  *      with other non-ptlrpcd, like "ls -l" itself (we want to the "ls -l"
 467  *      thread, statahead thread, and ptlrpcd thread can run in parallel), under
 468  *      such case, the statahead async RPCs can not be processed in time, it is
 469  *      unexpected. If ptlrpcd_0 can be re-scheduled on other CPU core, it may
 470  *      be better. But it breaks former data transfer policy.
 471  *
 472  *      So we shouldn't be blind for avoiding the data transfer. We make some
 473  *      compromise: divide the ptlrpcd threds pool into two parts. One part is
 474  *      for bound mode, each ptlrpcd thread in this part is bound to some CPU
 475  *      core. The other part is for free mode, all the ptlrpcd threads in the
 476  *      part can be scheduled on any CPU core. We specify some partnership
 477  *      between bound mode ptlrpcd thread(s) and free mode ptlrpcd thread(s),
 478  *      and the async RPC load within the partners are shared.
 479  *
 480  *      It can partly avoid data transfer cross-CPU (if the bound mode ptlrpcd
 481  *      thread can be scheduled in time), and try to guarantee the async RPC
 482  *      processed ASAP (as long as the free mode ptlrpcd thread can be scheduled
 483  *      on any CPU core).
 484  *
 485  *      As for how to specify the partnership between bound mode ptlrpcd
 486  *      thread(s) and free mode ptlrpcd thread(s), the simplest way is to use
 487  *      <free bound> pair. In future, we can specify some more complex
 488  *      partnership based on the patches for CPU partition. But before such
 489  *      patches are available, we prefer to use the simplest one.
 490  */
 491 # ifdef CFS_CPU_MODE_NUMA
 492 # warning "fix ptlrpcd_bind() to use new CPU partition APIs"
 493 # endif
 494 static int ptlrpcd_bind(int index, int max)
 495 {
 496         struct ptlrpcd_ctl *pc;
 497         int rc = 0;
 498 #if defined(CONFIG_NUMA)
 499         cpumask_t mask;
 500 #endif
 501         ENTRY;
 502
 503         LASSERT(index <= max - 1);
 504         pc = &ptlrpcds->pd_threads[index];
 505         switch (ptlrpcd_bind_policy) {
 506         case PDB_POLICY_NONE:
 507                 pc->pc_npartners = -1;
 508                 break;
 509         case PDB_POLICY_FULL:
 510                 pc->pc_npartners = 0;
 511                 set_bit(LIOD_BIND, &pc->pc_flags);
 512                 break;
 513         case PDB_POLICY_PAIR:
 514                 LASSERT(max % 2 == 0);
 515                 pc->pc_npartners = 1;
 516                 break;
 517         case PDB_POLICY_NEIGHBOR:
 518 #if defined(CONFIG_NUMA)
 519         {
 520                 int i;
 521                 mask = *cpumask_of_node(cpu_to_node(index));
 522                 for (i = max; i < num_online_cpus(); i++)
 523                         cpu_clear(i, mask);
 524                 pc->pc_npartners = cpus_weight(mask) - 1;
 525                 set_bit(LIOD_BIND, &pc->pc_flags);
 526         }
 527 #else
 528                 LASSERT(max >= 3);
 529                 pc->pc_npartners = 2;
 530 #endif
 531                 break;
 532         default:
 533                 CERROR("unknown ptlrpcd bind policy %d\n", ptlrpcd_bind_policy);
 534                 rc = -EINVAL;
 535         }
 536
 537         if (rc == 0 && pc->pc_npartners > 0) {
 538                 OBD_ALLOC(pc->pc_partners,
 539                           sizeof(struct ptlrpcd_ctl *) * pc->pc_npartners);
 540                 if (pc->pc_partners == NULL) {
 541                         pc->pc_npartners = 0;
 542                         rc = -ENOMEM;
 543                 } else {
 544                         switch (ptlrpcd_bind_policy) {
 545                         case PDB_POLICY_PAIR:
 546                                 if (index & 0x1) {
 547                                         set_bit(LIOD_BIND, &pc->pc_flags);
 548                                         pc->pc_partners[0] = &ptlrpcds->
 549                                                 pd_threads[index - 1];
 550                                         ptlrpcds->pd_threads[index - 1].
 551                                                 pc_partners[0] = pc;
 552                                 }
 553                                 break;
 554                         case PDB_POLICY_NEIGHBOR:
 555 #if defined(CONFIG_NUMA)
 556                         {
 557                                 struct ptlrpcd_ctl *ppc;
 558                                 int i, pidx;
 559                                 /* partners are cores in the same NUMA node.
 560                                  * setup partnership only with ptlrpcd threads
 561                                  * that are already initialized
 562                                  */
 563                                 for (pidx = 0, i = 0; i < index; i++) {
 564                                         if (cpu_isset(i, mask)) {
 565                                                 ppc = &ptlrpcds->pd_threads[i];
 566                                                 pc->pc_partners[pidx++] = ppc;
 567                                                 ppc->pc_partners[ppc->
 568                                                           pc_npartners++] = pc;
 569                                         }
 570                                 }
 571                                 /* adjust number of partners to the number
 572                                  * of partnership really setup */
 573                                 pc->pc_npartners = pidx;
 574                         }
 575 #else
 576                                 if (index & 0x1)
 577                                         set_bit(LIOD_BIND, &pc->pc_flags);
 578                                 if (index > 0) {
 579                                         pc->pc_partners[0] = &ptlrpcds->
 580                                                 pd_threads[index - 1];
 581                                         ptlrpcds->pd_threads[index - 1].
 582                                                 pc_partners[1] = pc;
 583                                         if (index == max - 1) {
 584                                                 pc->pc_partners[1] =
 585                                                 &ptlrpcds->pd_threads[0];
 586                                                 ptlrpcds->pd_threads[0].
 587                                                 pc_partners[0] = pc;
 588                                         }
 589                                 }
 590 #endif
 591                                 break;
 592                         }
 593                 }
 594         }
 595
 596         RETURN(rc);
 597 }
 598
 599
 600 int ptlrpcd_start(int index, int max, const char *name, struct ptlrpcd_ctl *pc)
 601 {
 602         int rc;
 603         ENTRY;
 604
 605         /*
 606          * Do not allow start second thread for one pc.
 607          */
 608         if (test_and_set_bit(LIOD_START, &pc->pc_flags)) {
 609                 CWARN("Starting second thread (%s) for same pc %p\n",
 610                       name, pc);
 611                 RETURN(0);
 612         }
 613
 614         pc->pc_index = index;
 615         init_completion(&pc->pc_starting);
 616         init_completion(&pc->pc_finishing);
 617         spin_lock_init(&pc->pc_lock);
 618         strlcpy(pc->pc_name, name, sizeof(pc->pc_name));
 619         pc->pc_set = ptlrpc_prep_set();
 620         if (pc->pc_set == NULL)
 621                 GOTO(out, rc = -ENOMEM);
 622
 623         /*
 624          * So far only "client" ptlrpcd uses an environment. In the future,
 625          * ptlrpcd thread (or a thread-set) has to be given an argument,
 626          * describing its "scope".
 627          */
 628         rc = lu_context_init(&pc->pc_env.le_ctx, LCT_CL_THREAD|LCT_REMEMBER);
 629         if (rc != 0)
 630                 GOTO(out_set, rc);
 631
 632         {
 633                 struct task_struct *task;
 634                 if (index >= 0) {
 635                         rc = ptlrpcd_bind(index, max);
 636                         if (rc < 0)
 637                                 GOTO(out_env, rc);
 638                 }
 639
 640                 task = kthread_run(ptlrpcd, pc, pc->pc_name);
 641                 if (IS_ERR(task))
 642                         GOTO(out_env, rc = PTR_ERR(task));
 643
 644                 wait_for_completion(&pc->pc_starting);
 645         }
 646         RETURN(0);
 647
 648 out_env:
 649         lu_context_fini(&pc->pc_env.le_ctx);
 650
 651 out_set:
 652         if (pc->pc_set != NULL) {
 653                 struct ptlrpc_request_set *set = pc->pc_set;
 654
 655                 spin_lock(&pc->pc_lock);
 656                 pc->pc_set = NULL;
 657                 spin_unlock(&pc->pc_lock);
 658                 ptlrpc_set_destroy(set);
 659         }
 660         clear_bit(LIOD_BIND, &pc->pc_flags);
 661 out:
 662         clear_bit(LIOD_START, &pc->pc_flags);
 663         RETURN(rc);
 664 }
 665
 666 void ptlrpcd_stop(struct ptlrpcd_ctl *pc, int force)
 667 {
 668         ENTRY;
 669
 670         if (!test_bit(LIOD_START, &pc->pc_flags)) {
 671                 CWARN("Thread for pc %p was not started\n", pc);
 672                 goto out;
 673         }
 674
 675         set_bit(LIOD_STOP, &pc->pc_flags);
 676         if (force)
 677                 set_bit(LIOD_FORCE, &pc->pc_flags);
 678         wake_up(&pc->pc_set->set_waitq);
 679
 680 out:
 681         EXIT;
 682 }
 683
 684 void ptlrpcd_free(struct ptlrpcd_ctl *pc)
 685 {
 686         struct ptlrpc_request_set *set = pc->pc_set;
 687         ENTRY;
 688
 689         if (!test_bit(LIOD_START, &pc->pc_flags)) {
 690                 CWARN("Thread for pc %p was not started\n", pc);
 691                 goto out;
 692         }
 693
 694         wait_for_completion(&pc->pc_finishing);
 695         lu_context_fini(&pc->pc_env.le_ctx);
 696
 697         spin_lock(&pc->pc_lock);
 698         pc->pc_set = NULL;
 699         spin_unlock(&pc->pc_lock);
 700         ptlrpc_set_destroy(set);
 701
 702         clear_bit(LIOD_START, &pc->pc_flags);
 703         clear_bit(LIOD_STOP, &pc->pc_flags);
 704         clear_bit(LIOD_FORCE, &pc->pc_flags);
 705         clear_bit(LIOD_BIND, &pc->pc_flags);
 706
 707 out:
 708         if (pc->pc_npartners > 0) {
 709                 LASSERT(pc->pc_partners != NULL);
 710
 711                 OBD_FREE(pc->pc_partners,
 712                          sizeof(struct ptlrpcd_ctl *) * pc->pc_npartners);
 713                 pc->pc_partners = NULL;
 714         }
 715         pc->pc_npartners = 0;
 716         EXIT;
 717 }
 718
 719 static void ptlrpcd_fini(void)
 720 {
 721         int i;
 722         ENTRY;
 723
 724         if (ptlrpcds != NULL) {
 725                 for (i = 0; i < ptlrpcds->pd_nthreads; i++)
 726                         ptlrpcd_stop(&ptlrpcds->pd_threads[i], 0);
 727                 for (i = 0; i < ptlrpcds->pd_nthreads; i++)
 728                         ptlrpcd_free(&ptlrpcds->pd_threads[i]);
 729                 ptlrpcd_stop(&ptlrpcds->pd_thread_rcv, 0);
 730                 ptlrpcd_free(&ptlrpcds->pd_thread_rcv);
 731                 OBD_FREE(ptlrpcds, ptlrpcds->pd_size);
 732                 ptlrpcds = NULL;
 733         }
 734
 735         EXIT;
 736 }
 737
 738 static int ptlrpcd_init(void)
 739 {
 740         int     nthreads = num_online_cpus();
 741         char    name[16];
 742         int     size, i = -1, j, rc = 0;
 743         ENTRY;
 744
 745         if (max_ptlrpcds > 0 && max_ptlrpcds < nthreads)
 746                 nthreads = max_ptlrpcds;
 747         if (nthreads < 2)
 748                 nthreads = 2;
 749         if (nthreads < 3 && ptlrpcd_bind_policy == PDB_POLICY_NEIGHBOR)
 750                 ptlrpcd_bind_policy = PDB_POLICY_PAIR;
 751         else if (nthreads % 2 != 0 && ptlrpcd_bind_policy == PDB_POLICY_PAIR)
 752                 nthreads &= ~1; /* make sure it is even */
 753
 754         size = offsetof(struct ptlrpcd, pd_threads[nthreads]);
 755         OBD_ALLOC(ptlrpcds, size);
 756         if (ptlrpcds == NULL)
 757                 GOTO(out, rc = -ENOMEM);
 758
 759         snprintf(name, 15, "ptlrpcd_rcv");
 760         set_bit(LIOD_RECOVERY, &ptlrpcds->pd_thread_rcv.pc_flags);
 761         rc = ptlrpcd_start(-1, nthreads, name, &ptlrpcds->pd_thread_rcv);
 762         if (rc < 0)
 763                 GOTO(out, rc);
 764
 765         /* XXX: We start nthreads ptlrpc daemons. Each of them can process any
 766          *      non-recovery async RPC to improve overall async RPC efficiency.
 767          *
 768          *      But there are some issues with async I/O RPCs and async non-I/O
 769          *      RPCs processed in the same set under some cases. The ptlrpcd may
 770          *      be blocked by some async I/O RPC(s), then will cause other async
 771          *      non-I/O RPC(s) can not be processed in time.
 772          *
 773          *      Maybe we should distinguish blocked async RPCs from non-blocked
 774          *      async RPCs, and process them in different ptlrpcd sets to avoid
 775          *      unnecessary dependency. But how to distribute async RPCs load
 776          *      among all the ptlrpc daemons becomes another trouble. */
 777         for (i = 0; i < nthreads; i++) {
 778                 snprintf(name, 15, "ptlrpcd_%d", i);
 779                 rc = ptlrpcd_start(i, nthreads, name, &ptlrpcds->pd_threads[i]);
 780                 if (rc < 0)
 781                         GOTO(out, rc);
 782         }
 783
 784         ptlrpcds->pd_size = size;
 785         ptlrpcds->pd_index = 0;
 786         ptlrpcds->pd_nthreads = nthreads;
 787
 788 out:
 789         if (rc != 0 && ptlrpcds != NULL) {
 790                 for (j = 0; j <= i; j++)
 791                         ptlrpcd_stop(&ptlrpcds->pd_threads[j], 0);
 792                 for (j = 0; j <= i; j++)
 793                         ptlrpcd_free(&ptlrpcds->pd_threads[j]);
 794                 ptlrpcd_stop(&ptlrpcds->pd_thread_rcv, 0);
 795                 ptlrpcd_free(&ptlrpcds->pd_thread_rcv);
 796                 OBD_FREE(ptlrpcds, size);
 797                 ptlrpcds = NULL;
 798         }
 799
 800         RETURN(rc);
 801 }
 802
 803 int ptlrpcd_addref(void)
 804 {
 805         int rc = 0;
 806         ENTRY;
 807
 808         mutex_lock(&ptlrpcd_mutex);
 809         if (++ptlrpcd_users == 1) {
 810                 rc = ptlrpcd_init();
 811                 if (rc < 0)
 812                         ptlrpcd_users--;
 813         }
 814         mutex_unlock(&ptlrpcd_mutex);
 815         RETURN(rc);
 816 }
 817 EXPORT_SYMBOL(ptlrpcd_addref);
 818
 819 void ptlrpcd_decref(void)
 820 {
 821         mutex_lock(&ptlrpcd_mutex);
 822         if (--ptlrpcd_users == 0)
 823                 ptlrpcd_fini();
 824         mutex_unlock(&ptlrpcd_mutex);
 825 }
 826 EXPORT_SYMBOL(ptlrpcd_decref);
 827 /** @} ptlrpcd */