kernel/drivers/staging/lustre/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, 2012, 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 "../../include/linux/libcfs/libcfs.h"
  59
  60 #include "../include/lustre_net.h"
  61 #include "../include/lustre_lib.h"
  62 #include "../include/lustre_ha.h"
  63 #include "../include/obd_class.h"       /* for obd_zombie */
  64 #include "../include/obd_support.h"     /* for OBD_FAIL_CHECK */
  65 #include "../include/cl_object.h"       /* cl_env_{get,put}() */
  66 #include "../include/lprocfs_status.h"
  67
  68 #include "ptlrpc_internal.h"
  69
  70 struct ptlrpcd {
  71         int             pd_size;
  72         int             pd_index;
  73         int             pd_nthreads;
  74         struct ptlrpcd_ctl pd_thread_rcv;
  75         struct ptlrpcd_ctl pd_threads[0];
  76 };
  77
  78 static int max_ptlrpcds;
  79 module_param(max_ptlrpcds, int, 0644);
  80 MODULE_PARM_DESC(max_ptlrpcds, "Max ptlrpcd thread count to be started.");
  81
  82 static int ptlrpcd_bind_policy = PDB_POLICY_PAIR;
  83 module_param(ptlrpcd_bind_policy, int, 0644);
  84 MODULE_PARM_DESC(ptlrpcd_bind_policy, "Ptlrpcd threads binding mode.");
  85 static struct ptlrpcd *ptlrpcds;
  86
  87 struct mutex ptlrpcd_mutex;
  88 static int ptlrpcd_users;
  89
  90 void ptlrpcd_wake(struct ptlrpc_request *req)
  91 {
  92         struct ptlrpc_request_set *rq_set = req->rq_set;
  93
  94         LASSERT(rq_set != NULL);
  95
  96         wake_up(&rq_set->set_waitq);
  97 }
  98 EXPORT_SYMBOL(ptlrpcd_wake);
  99
 100 static struct ptlrpcd_ctl *
 101 ptlrpcd_select_pc(struct ptlrpc_request *req, pdl_policy_t policy, int index)
 102 {
 103         int idx = 0;
 104
 105         if (req != NULL && req->rq_send_state != LUSTRE_IMP_FULL)
 106                 return &ptlrpcds->pd_thread_rcv;
 107
 108         switch (policy) {
 109         case PDL_POLICY_SAME:
 110                 idx = smp_processor_id() % ptlrpcds->pd_nthreads;
 111                 break;
 112         case PDL_POLICY_LOCAL:
 113                 /* Before CPU partition patches available, process it the same
 114                  * as "PDL_POLICY_ROUND". */
 115 # ifdef CFS_CPU_MODE_NUMA
 116 # warning "fix this code to use new CPU partition APIs"
 117 # endif
 118                 /* Fall through to PDL_POLICY_ROUND until the CPU
 119                  * CPU partition patches are available. */
 120                 index = -1;
 121         case PDL_POLICY_PREFERRED:
 122                 if (index >= 0 && index < num_online_cpus()) {
 123                         idx = index % ptlrpcds->pd_nthreads;
 124                         break;
 125                 }
 126                 /* Fall through to PDL_POLICY_ROUND for bad index. */
 127         default:
 128                 /* Fall through to PDL_POLICY_ROUND for unknown policy. */
 129         case PDL_POLICY_ROUND:
 130                 /* We do not care whether it is strict load balance. */
 131                 idx = ptlrpcds->pd_index + 1;
 132                 if (idx == smp_processor_id())
 133                         idx++;
 134                 idx %= ptlrpcds->pd_nthreads;
 135                 ptlrpcds->pd_index = idx;
 136                 break;
 137         }
 138
 139         return &ptlrpcds->pd_threads[idx];
 140 }
 141
 142 /**
 143  * Move all request from an existing request set to the ptlrpcd queue.
 144  * All requests from the set must be in phase RQ_PHASE_NEW.
 145  */
 146 void ptlrpcd_add_rqset(struct ptlrpc_request_set *set)
 147 {
 148         struct list_head *tmp, *pos;
 149         struct ptlrpcd_ctl *pc;
 150         struct ptlrpc_request_set *new;
 151         int count, i;
 152
 153         pc = ptlrpcd_select_pc(NULL, PDL_POLICY_LOCAL, -1);
 154         new = pc->pc_set;
 155
 156         list_for_each_safe(pos, tmp, &set->set_requests) {
 157                 struct ptlrpc_request *req =
 158                         list_entry(pos, struct ptlrpc_request,
 159                                        rq_set_chain);
 160
 161                 LASSERT(req->rq_phase == RQ_PHASE_NEW);
 162                 req->rq_set = new;
 163                 req->rq_queued_time = cfs_time_current();
 164         }
 165
 166         spin_lock(&new->set_new_req_lock);
 167         list_splice_init(&set->set_requests, &new->set_new_requests);
 168         i = atomic_read(&set->set_remaining);
 169         count = atomic_add_return(i, &new->set_new_count);
 170         atomic_set(&set->set_remaining, 0);
 171         spin_unlock(&new->set_new_req_lock);
 172         if (count == i) {
 173                 wake_up(&new->set_waitq);
 174
 175                 /* XXX: It maybe unnecessary to wakeup all the partners. But to
 176                  *      guarantee the async RPC can be processed ASAP, we have
 177                  *      no other better choice. It maybe fixed in future. */
 178                 for (i = 0; i < pc->pc_npartners; i++)
 179                         wake_up(&pc->pc_partners[i]->pc_set->set_waitq);
 180         }
 181 }
 182 EXPORT_SYMBOL(ptlrpcd_add_rqset);
 183
 184 /**
 185  * Return transferred RPCs count.
 186  */
 187 static int ptlrpcd_steal_rqset(struct ptlrpc_request_set *des,
 188                                struct ptlrpc_request_set *src)
 189 {
 190         struct list_head *tmp, *pos;
 191         struct ptlrpc_request *req;
 192         int rc = 0;
 193
 194         spin_lock(&src->set_new_req_lock);
 195         if (likely(!list_empty(&src->set_new_requests))) {
 196                 list_for_each_safe(pos, tmp, &src->set_new_requests) {
 197                         req = list_entry(pos, struct ptlrpc_request,
 198                                              rq_set_chain);
 199                         req->rq_set = des;
 200                 }
 201                 list_splice_init(&src->set_new_requests,
 202                                      &des->set_requests);
 203                 rc = atomic_read(&src->set_new_count);
 204                 atomic_add(rc, &des->set_remaining);
 205                 atomic_set(&src->set_new_count, 0);
 206         }
 207         spin_unlock(&src->set_new_req_lock);
 208         return rc;
 209 }
 210
 211 /**
 212  * Requests that are added to the ptlrpcd queue are sent via
 213  * ptlrpcd_check->ptlrpc_check_set().
 214  */
 215 void ptlrpcd_add_req(struct ptlrpc_request *req, pdl_policy_t policy, int idx)
 216 {
 217         struct ptlrpcd_ctl *pc;
 218
 219         if (req->rq_reqmsg)
 220                 lustre_msg_set_jobid(req->rq_reqmsg, NULL);
 221
 222         spin_lock(&req->rq_lock);
 223         if (req->rq_invalid_rqset) {
 224                 struct l_wait_info lwi = LWI_TIMEOUT(cfs_time_seconds(5),
 225                                                      back_to_sleep, NULL);
 226
 227                 req->rq_invalid_rqset = 0;
 228                 spin_unlock(&req->rq_lock);
 229                 l_wait_event(req->rq_set_waitq, (req->rq_set == NULL), &lwi);
 230         } else if (req->rq_set) {
 231                 /* If we have a valid "rq_set", just reuse it to avoid double
 232                  * linked. */
 233                 LASSERT(req->rq_phase == RQ_PHASE_NEW);
 234                 LASSERT(req->rq_send_state == LUSTRE_IMP_REPLAY);
 235
 236                 /* ptlrpc_check_set will decrease the count */
 237                 atomic_inc(&req->rq_set->set_remaining);
 238                 spin_unlock(&req->rq_lock);
 239                 wake_up(&req->rq_set->set_waitq);
 240                 return;
 241         } else {
 242                 spin_unlock(&req->rq_lock);
 243         }
 244
 245         pc = ptlrpcd_select_pc(req, policy, idx);
 246
 247         DEBUG_REQ(D_INFO, req, "add req [%p] to pc [%s:%d]",
 248                   req, pc->pc_name, pc->pc_index);
 249
 250         ptlrpc_set_add_new_req(pc, req);
 251 }
 252 EXPORT_SYMBOL(ptlrpcd_add_req);
 253
 254 static inline void ptlrpc_reqset_get(struct ptlrpc_request_set *set)
 255 {
 256         atomic_inc(&set->set_refcount);
 257 }
 258
 259 /**
 260  * Check if there is more work to do on ptlrpcd set.
 261  * Returns 1 if yes.
 262  */
 263 static int ptlrpcd_check(struct lu_env *env, struct ptlrpcd_ctl *pc)
 264 {
 265         struct list_head *tmp, *pos;
 266         struct ptlrpc_request *req;
 267         struct ptlrpc_request_set *set = pc->pc_set;
 268         int rc = 0;
 269         int rc2;
 270
 271         if (atomic_read(&set->set_new_count)) {
 272                 spin_lock(&set->set_new_req_lock);
 273                 if (likely(!list_empty(&set->set_new_requests))) {
 274                         list_splice_init(&set->set_new_requests,
 275                                              &set->set_requests);
 276                         atomic_add(atomic_read(&set->set_new_count),
 277                                        &set->set_remaining);
 278                         atomic_set(&set->set_new_count, 0);
 279                         /*
 280                          * Need to calculate its timeout.
 281                          */
 282                         rc = 1;
 283                 }
 284                 spin_unlock(&set->set_new_req_lock);
 285         }
 286
 287         /* We should call lu_env_refill() before handling new requests to make
 288          * sure that env key the requests depending on really exists.
 289          */
 290         rc2 = lu_env_refill(env);
 291         if (rc2 != 0) {
 292                 /*
 293                  * XXX This is very awkward situation, because
 294                  * execution can neither continue (request
 295                  * interpreters assume that env is set up), nor repeat
 296                  * the loop (as this potentially results in a tight
 297                  * loop of -ENOMEM's).
 298                  *
 299                  * Fortunately, refill only ever does something when
 300                  * new modules are loaded, i.e., early during boot up.
 301                  */
 302                 CERROR("Failure to refill session: %d\n", rc2);
 303                 return rc;
 304         }
 305
 306         if (atomic_read(&set->set_remaining))
 307                 rc |= ptlrpc_check_set(env, set);
 308
 309         /* NB: ptlrpc_check_set has already moved completed request at the
 310          * head of seq::set_requests */
 311         list_for_each_safe(pos, tmp, &set->set_requests) {
 312                 req = list_entry(pos, struct ptlrpc_request, rq_set_chain);
 313                 if (req->rq_phase != RQ_PHASE_COMPLETE)
 314                         break;
 315
 316                 list_del_init(&req->rq_set_chain);
 317                 req->rq_set = NULL;
 318                 ptlrpc_req_finished(req);
 319         }
 320
 321         if (rc == 0) {
 322                 /*
 323                  * If new requests have been added, make sure to wake up.
 324                  */
 325                 rc = atomic_read(&set->set_new_count);
 326
 327                 /* If we have nothing to do, check whether we can take some
 328                  * work from our partner threads. */
 329                 if (rc == 0 && pc->pc_npartners > 0) {
 330                         struct ptlrpcd_ctl *partner;
 331                         struct ptlrpc_request_set *ps;
 332                         int first = pc->pc_cursor;
 333
 334                         do {
 335                                 partner = pc->pc_partners[pc->pc_cursor++];
 336                                 if (pc->pc_cursor >= pc->pc_npartners)
 337                                         pc->pc_cursor = 0;
 338                                 if (partner == NULL)
 339                                         continue;
 340
 341                                 spin_lock(&partner->pc_lock);
 342                                 ps = partner->pc_set;
 343                                 if (ps == NULL) {
 344                                         spin_unlock(&partner->pc_lock);
 345                                         continue;
 346                                 }
 347
 348                                 ptlrpc_reqset_get(ps);
 349                                 spin_unlock(&partner->pc_lock);
 350
 351                                 if (atomic_read(&ps->set_new_count)) {
 352                                         rc = ptlrpcd_steal_rqset(set, ps);
 353                                         if (rc > 0)
 354                                                 CDEBUG(D_RPCTRACE, "transfer %d async RPCs [%d->%d]\n",
 355                                                        rc, partner->pc_index,
 356                                                        pc->pc_index);
 357                                 }
 358                                 ptlrpc_reqset_put(ps);
 359                         } while (rc == 0 && pc->pc_cursor != first);
 360                 }
 361         }
 362
 363         return rc;
 364 }
 365
 366 /**
 367  * Main ptlrpcd thread.
 368  * ptlrpc's code paths like to execute in process context, so we have this
 369  * thread which spins on a set which contains the rpcs and sends them.
 370  *
 371  */
 372 static int ptlrpcd(void *arg)
 373 {
 374         struct ptlrpcd_ctl *pc = arg;
 375         struct ptlrpc_request_set *set = pc->pc_set;
 376         struct lu_env env = { .le_ses = NULL };
 377         int rc, exit = 0;
 378
 379         unshare_fs_struct();
 380 #if defined(CONFIG_SMP)
 381         if (test_bit(LIOD_BIND, &pc->pc_flags)) {
 382                 int index = pc->pc_index;
 383
 384                 if (index >= 0 && index < num_possible_cpus()) {
 385                         while (!cpu_online(index)) {
 386                                 if (++index >= num_possible_cpus())
 387                                         index = 0;
 388                         }
 389                         set_cpus_allowed_ptr(current,
 390                                         cpumask_of_node(cpu_to_node(index)));
 391                 }
 392         }
 393 #endif
 394         /*
 395          * XXX So far only "client" ptlrpcd uses an environment. In
 396          * the future, ptlrpcd thread (or a thread-set) has to given
 397          * an argument, describing its "scope".
 398          */
 399         rc = lu_context_init(&env.le_ctx,
 400                              LCT_CL_THREAD|LCT_REMEMBER|LCT_NOREF);
 401         complete(&pc->pc_starting);
 402
 403         if (rc != 0)
 404                 return rc;
 405
 406         /*
 407          * This mainloop strongly resembles ptlrpc_set_wait() except that our
 408          * set never completes.  ptlrpcd_check() calls ptlrpc_check_set() when
 409          * there are requests in the set. New requests come in on the set's
 410          * new_req_list and ptlrpcd_check() moves them into the set.
 411          */
 412         do {
 413                 struct l_wait_info lwi;
 414                 int timeout;
 415
 416                 timeout = ptlrpc_set_next_timeout(set);
 417                 lwi = LWI_TIMEOUT(cfs_time_seconds(timeout ? timeout : 1),
 418                                   ptlrpc_expired_set, set);
 419
 420                 lu_context_enter(&env.le_ctx);
 421                 l_wait_event(set->set_waitq,
 422                              ptlrpcd_check(&env, pc), &lwi);
 423                 lu_context_exit(&env.le_ctx);
 424
 425                 /*
 426                  * Abort inflight rpcs for forced stop case.
 427                  */
 428                 if (test_bit(LIOD_STOP, &pc->pc_flags)) {
 429                         if (test_bit(LIOD_FORCE, &pc->pc_flags))
 430                                 ptlrpc_abort_set(set);
 431                         exit++;
 432                 }
 433
 434                 /*
 435                  * Let's make one more loop to make sure that ptlrpcd_check()
 436                  * copied all raced new rpcs into the set so we can kill them.
 437                  */
 438         } while (exit < 2);
 439
 440         /*
 441          * Wait for inflight requests to drain.
 442          */
 443         if (!list_empty(&set->set_requests))
 444                 ptlrpc_set_wait(set);
 445         lu_context_fini(&env.le_ctx);
 446
 447         complete(&pc->pc_finishing);
 448
 449         return 0;
 450 }
 451
 452 /* XXX: We want multiple CPU cores to share the async RPC load. So we start many
 453  *      ptlrpcd threads. We also want to reduce the ptlrpcd overhead caused by
 454  *      data transfer cross-CPU cores. So we bind ptlrpcd thread to specified
 455  *      CPU core. But binding all ptlrpcd threads maybe cause response delay
 456  *      because of some CPU core(s) busy with other loads.
 457  *
 458  *      For example: "ls -l", some async RPCs for statahead are assigned to
 459  *      ptlrpcd_0, and ptlrpcd_0 is bound to CPU_0, but CPU_0 may be quite busy
 460  *      with other non-ptlrpcd, like "ls -l" itself (we want to the "ls -l"
 461  *      thread, statahead thread, and ptlrpcd thread can run in parallel), under
 462  *      such case, the statahead async RPCs can not be processed in time, it is
 463  *      unexpected. If ptlrpcd_0 can be re-scheduled on other CPU core, it may
 464  *      be better. But it breaks former data transfer policy.
 465  *
 466  *      So we shouldn't be blind for avoiding the data transfer. We make some
 467  *      compromise: divide the ptlrpcd threads pool into two parts. One part is
 468  *      for bound mode, each ptlrpcd thread in this part is bound to some CPU
 469  *      core. The other part is for free mode, all the ptlrpcd threads in the
 470  *      part can be scheduled on any CPU core. We specify some partnership
 471  *      between bound mode ptlrpcd thread(s) and free mode ptlrpcd thread(s),
 472  *      and the async RPC load within the partners are shared.
 473  *
 474  *      It can partly avoid data transfer cross-CPU (if the bound mode ptlrpcd
 475  *      thread can be scheduled in time), and try to guarantee the async RPC
 476  *      processed ASAP (as long as the free mode ptlrpcd thread can be scheduled
 477  *      on any CPU core).
 478  *
 479  *      As for how to specify the partnership between bound mode ptlrpcd
 480  *      thread(s) and free mode ptlrpcd thread(s), the simplest way is to use
 481  *      <free bound> pair. In future, we can specify some more complex
 482  *      partnership based on the patches for CPU partition. But before such
 483  *      patches are available, we prefer to use the simplest one.
 484  */
 485 # ifdef CFS_CPU_MODE_NUMA
 486 # warning "fix ptlrpcd_bind() to use new CPU partition APIs"
 487 # endif
 488 static int ptlrpcd_bind(int index, int max)
 489 {
 490         struct ptlrpcd_ctl *pc;
 491         int rc = 0;
 492 #if defined(CONFIG_NUMA)
 493         cpumask_t mask;
 494 #endif
 495
 496         LASSERT(index <= max - 1);
 497         pc = &ptlrpcds->pd_threads[index];
 498         switch (ptlrpcd_bind_policy) {
 499         case PDB_POLICY_NONE:
 500                 pc->pc_npartners = -1;
 501                 break;
 502         case PDB_POLICY_FULL:
 503                 pc->pc_npartners = 0;
 504                 set_bit(LIOD_BIND, &pc->pc_flags);
 505                 break;
 506         case PDB_POLICY_PAIR:
 507                 LASSERT(max % 2 == 0);
 508                 pc->pc_npartners = 1;
 509                 break;
 510         case PDB_POLICY_NEIGHBOR:
 511 #if defined(CONFIG_NUMA)
 512         {
 513                 int i;
 514                 cpumask_copy(&mask, cpumask_of_node(cpu_to_node(index)));
 515                 for (i = max; i < num_online_cpus(); i++)
 516                         cpumask_clear_cpu(i, &mask);
 517                 pc->pc_npartners = cpumask_weight(&mask) - 1;
 518                 set_bit(LIOD_BIND, &pc->pc_flags);
 519         }
 520 #else
 521                 LASSERT(max >= 3);
 522                 pc->pc_npartners = 2;
 523 #endif
 524                 break;
 525         default:
 526                 CERROR("unknown ptlrpcd bind policy %d\n", ptlrpcd_bind_policy);
 527                 rc = -EINVAL;
 528         }
 529
 530         if (rc == 0 && pc->pc_npartners > 0) {
 531                 OBD_ALLOC(pc->pc_partners,
 532                           sizeof(struct ptlrpcd_ctl *) * pc->pc_npartners);
 533                 if (pc->pc_partners == NULL) {
 534                         pc->pc_npartners = 0;
 535                         rc = -ENOMEM;
 536                 } else {
 537                         switch (ptlrpcd_bind_policy) {
 538                         case PDB_POLICY_PAIR:
 539                                 if (index & 0x1) {
 540                                         set_bit(LIOD_BIND, &pc->pc_flags);
 541                                         pc->pc_partners[0] = &ptlrpcds->
 542                                                 pd_threads[index - 1];
 543                                         ptlrpcds->pd_threads[index - 1].
 544                                                 pc_partners[0] = pc;
 545                                 }
 546                                 break;
 547                         case PDB_POLICY_NEIGHBOR:
 548 #if defined(CONFIG_NUMA)
 549                         {
 550                                 struct ptlrpcd_ctl *ppc;
 551                                 int i, pidx;
 552                                 /* partners are cores in the same NUMA node.
 553                                  * setup partnership only with ptlrpcd threads
 554                                  * that are already initialized
 555                                  */
 556                                 for (pidx = 0, i = 0; i < index; i++) {
 557                                         if (cpumask_test_cpu(i, &mask)) {
 558                                                 ppc = &ptlrpcds->pd_threads[i];
 559                                                 pc->pc_partners[pidx++] = ppc;
 560                                                 ppc->pc_partners[ppc->
 561                                                           pc_npartners++] = pc;
 562                                         }
 563                                 }
 564                                 /* adjust number of partners to the number
 565                                  * of partnership really setup */
 566                                 pc->pc_npartners = pidx;
 567                         }
 568 #else
 569                                 if (index & 0x1)
 570                                         set_bit(LIOD_BIND, &pc->pc_flags);
 571                                 if (index > 0) {
 572                                         pc->pc_partners[0] = &ptlrpcds->
 573                                                 pd_threads[index - 1];
 574                                         ptlrpcds->pd_threads[index - 1].
 575                                                 pc_partners[1] = pc;
 576                                         if (index == max - 1) {
 577                                                 pc->pc_partners[1] =
 578                                                 &ptlrpcds->pd_threads[0];
 579                                                 ptlrpcds->pd_threads[0].
 580                                                 pc_partners[0] = pc;
 581                                         }
 582                                 }
 583 #endif
 584                                 break;
 585                         }
 586                 }
 587         }
 588
 589         return rc;
 590 }
 591
 592
 593 int ptlrpcd_start(int index, int max, const char *name, struct ptlrpcd_ctl *pc)
 594 {
 595         int rc;
 596
 597         /*
 598          * Do not allow start second thread for one pc.
 599          */
 600         if (test_and_set_bit(LIOD_START, &pc->pc_flags)) {
 601                 CWARN("Starting second thread (%s) for same pc %p\n",
 602                       name, pc);
 603                 return 0;
 604         }
 605
 606         pc->pc_index = index;
 607         init_completion(&pc->pc_starting);
 608         init_completion(&pc->pc_finishing);
 609         spin_lock_init(&pc->pc_lock);
 610         strlcpy(pc->pc_name, name, sizeof(pc->pc_name));
 611         pc->pc_set = ptlrpc_prep_set();
 612         if (pc->pc_set == NULL) {
 613                 rc = -ENOMEM;
 614                 goto out;
 615         }
 616
 617         /*
 618          * So far only "client" ptlrpcd uses an environment. In the future,
 619          * ptlrpcd thread (or a thread-set) has to be given an argument,
 620          * describing its "scope".
 621          */
 622         rc = lu_context_init(&pc->pc_env.le_ctx, LCT_CL_THREAD|LCT_REMEMBER);
 623         if (rc != 0)
 624                 goto out_set;
 625
 626         {
 627                 struct task_struct *task;
 628                 if (index >= 0) {
 629                         rc = ptlrpcd_bind(index, max);
 630                         if (rc < 0)
 631                                 goto out_env;
 632                 }
 633
 634                 task = kthread_run(ptlrpcd, pc, "%s", pc->pc_name);
 635                 if (IS_ERR(task)) {
 636                         rc = PTR_ERR(task);
 637                         goto out_env;
 638                 }
 639
 640                 wait_for_completion(&pc->pc_starting);
 641         }
 642         return 0;
 643
 644 out_env:
 645         lu_context_fini(&pc->pc_env.le_ctx);
 646
 647 out_set:
 648         if (pc->pc_set != NULL) {
 649                 struct ptlrpc_request_set *set = pc->pc_set;
 650
 651                 spin_lock(&pc->pc_lock);
 652                 pc->pc_set = NULL;
 653                 spin_unlock(&pc->pc_lock);
 654                 ptlrpc_set_destroy(set);
 655         }
 656         clear_bit(LIOD_BIND, &pc->pc_flags);
 657
 658 out:
 659         clear_bit(LIOD_START, &pc->pc_flags);
 660         return rc;
 661 }
 662
 663 void ptlrpcd_stop(struct ptlrpcd_ctl *pc, int force)
 664 {
 665         if (!test_bit(LIOD_START, &pc->pc_flags)) {
 666                 CWARN("Thread for pc %p was not started\n", pc);
 667                 return;
 668         }
 669
 670         set_bit(LIOD_STOP, &pc->pc_flags);
 671         if (force)
 672                 set_bit(LIOD_FORCE, &pc->pc_flags);
 673         wake_up(&pc->pc_set->set_waitq);
 674 }
 675
 676 void ptlrpcd_free(struct ptlrpcd_ctl *pc)
 677 {
 678         struct ptlrpc_request_set *set = pc->pc_set;
 679
 680         if (!test_bit(LIOD_START, &pc->pc_flags)) {
 681                 CWARN("Thread for pc %p was not started\n", pc);
 682                 goto out;
 683         }
 684
 685         wait_for_completion(&pc->pc_finishing);
 686         lu_context_fini(&pc->pc_env.le_ctx);
 687
 688         spin_lock(&pc->pc_lock);
 689         pc->pc_set = NULL;
 690         spin_unlock(&pc->pc_lock);
 691         ptlrpc_set_destroy(set);
 692
 693         clear_bit(LIOD_START, &pc->pc_flags);
 694         clear_bit(LIOD_STOP, &pc->pc_flags);
 695         clear_bit(LIOD_FORCE, &pc->pc_flags);
 696         clear_bit(LIOD_BIND, &pc->pc_flags);
 697
 698 out:
 699         if (pc->pc_npartners > 0) {
 700                 LASSERT(pc->pc_partners != NULL);
 701
 702                 OBD_FREE(pc->pc_partners,
 703                          sizeof(struct ptlrpcd_ctl *) * pc->pc_npartners);
 704                 pc->pc_partners = NULL;
 705         }
 706         pc->pc_npartners = 0;
 707 }
 708
 709 static void ptlrpcd_fini(void)
 710 {
 711         int i;
 712
 713         if (ptlrpcds != NULL) {
 714                 for (i = 0; i < ptlrpcds->pd_nthreads; i++)
 715                         ptlrpcd_stop(&ptlrpcds->pd_threads[i], 0);
 716                 for (i = 0; i < ptlrpcds->pd_nthreads; i++)
 717                         ptlrpcd_free(&ptlrpcds->pd_threads[i]);
 718                 ptlrpcd_stop(&ptlrpcds->pd_thread_rcv, 0);
 719                 ptlrpcd_free(&ptlrpcds->pd_thread_rcv);
 720                 OBD_FREE(ptlrpcds, ptlrpcds->pd_size);
 721                 ptlrpcds = NULL;
 722         }
 723 }
 724
 725 static int ptlrpcd_init(void)
 726 {
 727         int nthreads = num_online_cpus();
 728         char name[16];
 729         int size, i = -1, j, rc = 0;
 730
 731         if (max_ptlrpcds > 0 && max_ptlrpcds < nthreads)
 732                 nthreads = max_ptlrpcds;
 733         if (nthreads < 2)
 734                 nthreads = 2;
 735         if (nthreads < 3 && ptlrpcd_bind_policy == PDB_POLICY_NEIGHBOR)
 736                 ptlrpcd_bind_policy = PDB_POLICY_PAIR;
 737         else if (nthreads % 2 != 0 && ptlrpcd_bind_policy == PDB_POLICY_PAIR)
 738                 nthreads &= ~1; /* make sure it is even */
 739
 740         size = offsetof(struct ptlrpcd, pd_threads[nthreads]);
 741         OBD_ALLOC(ptlrpcds, size);
 742         if (ptlrpcds == NULL) {
 743                 rc = -ENOMEM;
 744                 goto out;
 745         }
 746
 747         snprintf(name, sizeof(name), "ptlrpcd_rcv");
 748         set_bit(LIOD_RECOVERY, &ptlrpcds->pd_thread_rcv.pc_flags);
 749         rc = ptlrpcd_start(-1, nthreads, name, &ptlrpcds->pd_thread_rcv);
 750         if (rc < 0)
 751                 goto out;
 752
 753         /* XXX: We start nthreads ptlrpc daemons. Each of them can process any
 754          *      non-recovery async RPC to improve overall async RPC efficiency.
 755          *
 756          *      But there are some issues with async I/O RPCs and async non-I/O
 757          *      RPCs processed in the same set under some cases. The ptlrpcd may
 758          *      be blocked by some async I/O RPC(s), then will cause other async
 759          *      non-I/O RPC(s) can not be processed in time.
 760          *
 761          *      Maybe we should distinguish blocked async RPCs from non-blocked
 762          *      async RPCs, and process them in different ptlrpcd sets to avoid
 763          *      unnecessary dependency. But how to distribute async RPCs load
 764          *      among all the ptlrpc daemons becomes another trouble. */
 765         for (i = 0; i < nthreads; i++) {
 766                 snprintf(name, sizeof(name), "ptlrpcd_%d", i);
 767                 rc = ptlrpcd_start(i, nthreads, name, &ptlrpcds->pd_threads[i]);
 768                 if (rc < 0)
 769                         goto out;
 770         }
 771
 772         ptlrpcds->pd_size = size;
 773         ptlrpcds->pd_index = 0;
 774         ptlrpcds->pd_nthreads = nthreads;
 775
 776 out:
 777         if (rc != 0 && ptlrpcds != NULL) {
 778                 for (j = 0; j <= i; j++)
 779                         ptlrpcd_stop(&ptlrpcds->pd_threads[j], 0);
 780                 for (j = 0; j <= i; j++)
 781                         ptlrpcd_free(&ptlrpcds->pd_threads[j]);
 782                 ptlrpcd_stop(&ptlrpcds->pd_thread_rcv, 0);
 783                 ptlrpcd_free(&ptlrpcds->pd_thread_rcv);
 784                 OBD_FREE(ptlrpcds, size);
 785                 ptlrpcds = NULL;
 786         }
 787
 788         return 0;
 789 }
 790
 791 int ptlrpcd_addref(void)
 792 {
 793         int rc = 0;
 794
 795         mutex_lock(&ptlrpcd_mutex);
 796         if (++ptlrpcd_users == 1)
 797                 rc = ptlrpcd_init();
 798         mutex_unlock(&ptlrpcd_mutex);
 799         return rc;
 800 }
 801 EXPORT_SYMBOL(ptlrpcd_addref);
 802
 803 void ptlrpcd_decref(void)
 804 {
 805         mutex_lock(&ptlrpcd_mutex);
 806         if (--ptlrpcd_users == 0)
 807                 ptlrpcd_fini();
 808         mutex_unlock(&ptlrpcd_mutex);
 809 }
 810 EXPORT_SYMBOL(ptlrpcd_decref);
 811 /** @} ptlrpcd */