lustre/ldlm/ldlm_request.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  *  Copyright (C) 2002 Cluster File Systems, Inc.
   5  *
   6  *   This file is part of Lustre, http://www.lustre.org.
   7  *
   8  *   Lustre is free software; you can redistribute it and/or
   9  *   modify it under the terms of version 2 of the GNU General Public
  10  *   License as published by the Free Software Foundation.
  11  *
  12  *   Lustre is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with Lustre; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #define DEBUG_SUBSYSTEM S_LDLM
  23
  24 #include <linux/lustre_dlm.h>
  25 #include <linux/obd_class.h>
  26 #include <linux/obd.h>
  27
  28 static int interrupted_completion_wait(void *data)
  29 {
  30         RETURN(1);
  31 }
  32
  33 static int expired_completion_wait(void *data)
  34 {
  35         struct ldlm_lock *lock = data;
  36         struct ptlrpc_connection *conn;
  37         struct obd_device *obd;
  38
  39         if (!lock)
  40                 CERROR("NULL lock\n");
  41         else if (!lock->l_connh)
  42                 CERROR("lock %p has NULL connh\n", lock);
  43         else if (!(obd = class_conn2obd(lock->l_connh)))
  44                 CERROR("lock %p has NULL obd\n", lock);
  45         else if (!(conn = obd->u.cli.cl_import.imp_connection))
  46                 CERROR("lock %p has NULL connection\n", lock);
  47         else
  48                 class_signal_connection_failure(conn);
  49         RETURN(0);
  50 }
  51
  52 int ldlm_completion_ast(struct ldlm_lock *lock, int flags)
  53 {
  54         struct l_wait_info lwi =
  55                 LWI_TIMEOUT_INTR(obd_timeout * HZ, expired_completion_wait,
  56                                  interrupted_completion_wait, lock);
  57         int rc = 0;
  58         ENTRY;
  59
  60         if (flags == LDLM_FL_WAIT_NOREPROC)
  61                 goto noreproc;
  62
  63         if (flags == 0) {
  64                 wake_up(&lock->l_waitq);
  65                 RETURN(0);
  66         }
  67
  68         if (!(flags & (LDLM_FL_BLOCK_WAIT | LDLM_FL_BLOCK_GRANTED |
  69                        LDLM_FL_BLOCK_CONV)))
  70                 RETURN(0);
  71
  72         LDLM_DEBUG(lock, "client-side enqueue returned a blocked lock, "
  73                    "sleeping");
  74         ldlm_lock_dump(lock);
  75         ldlm_reprocess_all(lock->l_resource);
  76
  77  noreproc:
  78         /* Go to sleep until the lock is granted or cancelled. */
  79         rc = l_wait_event(lock->l_waitq,
  80                           ((lock->l_req_mode == lock->l_granted_mode) ||
  81                            (lock->l_flags & LDLM_FL_DESTROYED)), &lwi);
  82
  83         if (lock->l_flags & LDLM_FL_DESTROYED) {
  84                 LDLM_DEBUG(lock, "client-side enqueue waking up: destroyed");
  85                 RETURN(-EIO);
  86         }
  87
  88         if (rc) {
  89                 LDLM_DEBUG(lock, "client-side enqueue waking up: failed (%d)",
  90                            rc);
  91                 RETURN(rc);
  92         }
  93
  94         LDLM_DEBUG(lock, "client-side enqueue waking up: granted");
  95         RETURN(0);
  96 }
  97
  98 static int ldlm_cli_enqueue_local(struct ldlm_namespace *ns,
  99                                   struct lustre_handle *parent_lockh,
 100                                   __u64 *res_id,
 101                                   __u32 type,
 102                                   void *cookie, int cookielen,
 103                                   ldlm_mode_t mode,
 104                                   int *flags,
 105                                   ldlm_completion_callback completion,
 106                                   ldlm_blocking_callback blocking,
 107                                   void *data,
 108                                   __u32 data_len,
 109                                   struct lustre_handle *lockh)
 110 {
 111         struct ldlm_lock *lock;
 112         int err;
 113         ENTRY;
 114
 115         if (ns->ns_client) {
 116                 CERROR("Trying to enqueue local lock in a shadow namespace\n");
 117                 LBUG();
 118         }
 119
 120         lock = ldlm_lock_create(ns, parent_lockh, res_id, type, mode, data,
 121                                 data_len);
 122         if (!lock)
 123                 GOTO(out_nolock, err = -ENOMEM);
 124         LDLM_DEBUG(lock, "client-side local enqueue handler, new lock created");
 125
 126         ldlm_lock_addref_internal(lock, mode);
 127         ldlm_lock2handle(lock, lockh);
 128         lock->l_connh = NULL;
 129
 130         err = ldlm_lock_enqueue(lock, cookie, cookielen, flags, completion,
 131                                 blocking);
 132         if (err != ELDLM_OK)
 133                 GOTO(out, err);
 134
 135         if (type == LDLM_EXTENT)
 136                 memcpy(cookie, &lock->l_extent, sizeof(lock->l_extent));
 137         if ((*flags) & LDLM_FL_LOCK_CHANGED)
 138                 memcpy(res_id, lock->l_resource->lr_name, sizeof(*res_id));
 139
 140         LDLM_DEBUG_NOLOCK("client-side local enqueue handler END (lock %p)",
 141                           lock);
 142
 143         if (lock->l_completion_ast)
 144                 lock->l_completion_ast(lock, *flags);
 145
 146         LDLM_DEBUG(lock, "client-side local enqueue END");
 147         EXIT;
 148  out:
 149         LDLM_LOCK_PUT(lock);
 150  out_nolock:
 151         return err;
 152 }
 153
 154 int ldlm_cli_enqueue(struct lustre_handle *connh,
 155                      struct ptlrpc_request *req,
 156                      struct ldlm_namespace *ns,
 157                      struct lustre_handle *parent_lock_handle,
 158                      __u64 *res_id,
 159                      __u32 type,
 160                      void *cookie, int cookielen,
 161                      ldlm_mode_t mode,
 162                      int *flags,
 163                      ldlm_completion_callback completion,
 164                      ldlm_blocking_callback blocking,
 165                      void *data,
 166                      __u32 data_len,
 167                      struct lustre_handle *lockh)
 168 {
 169         struct ldlm_lock *lock;
 170         struct ldlm_request *body;
 171         struct ldlm_reply *reply;
 172         int rc, size = sizeof(*body), req_passed_in = 1, is_replay;
 173         ENTRY;
 174
 175         is_replay = *flags & LDLM_FL_REPLAY;
 176         LASSERT(connh != NULL || !is_replay);
 177
 178         if (connh == NULL)
 179                 return ldlm_cli_enqueue_local(ns, parent_lock_handle, res_id,
 180                                               type, cookie, cookielen, mode,
 181                                               flags, completion, blocking, data,
 182                                               data_len, lockh);
 183
 184         /* If we're replaying this lock, just check some invariants.
 185          * If we're creating a new lock, get everything all setup nice. */
 186         if (is_replay) {
 187                 lock = ldlm_handle2lock(lockh);
 188                 LDLM_DEBUG(lock, "client-side enqueue START");
 189                 LASSERT(connh == lock->l_connh);
 190         } else {
 191                 lock = ldlm_lock_create(ns, parent_lock_handle, res_id, type,
 192                                         mode, data, data_len);
 193                 if (lock == NULL)
 194                         GOTO(out_nolock, rc = -ENOMEM);
 195                 LDLM_DEBUG(lock, "client-side enqueue START");
 196                 /* for the local lock, add the reference */
 197                 ldlm_lock_addref_internal(lock, mode);
 198                 ldlm_lock2handle(lock, lockh);
 199                 if (type == LDLM_EXTENT)
 200                         memcpy(&lock->l_extent, cookie,
 201                                sizeof(body->lock_desc.l_extent));
 202         }
 203
 204         if (req == NULL) {
 205                 req = ptlrpc_prep_req(class_conn2cliimp(connh), LDLM_ENQUEUE, 1,
 206                                       &size, NULL);
 207                 if (!req)
 208                         GOTO(out, rc = -ENOMEM);
 209                 req_passed_in = 0;
 210         } else if (req->rq_reqmsg->buflens[0] != sizeof(*body))
 211                 LBUG();
 212
 213         /* Dump lock data into the request buffer */
 214         body = lustre_msg_buf(req->rq_reqmsg, 0);
 215         ldlm_lock2desc(lock, &body->lock_desc);
 216         body->lock_flags = *flags;
 217
 218         memcpy(&body->lock_handle1, lockh, sizeof(*lockh));
 219         if (parent_lock_handle)
 220                 memcpy(&body->lock_handle2, parent_lock_handle,
 221                        sizeof(body->lock_handle2));
 222
 223         /* Continue as normal. */
 224         if (!req_passed_in) {
 225                 size = sizeof(*reply);
 226                 req->rq_replen = lustre_msg_size(1, &size);
 227         }
 228         lock->l_connh = connh;
 229         lock->l_export = NULL;
 230
 231         LDLM_DEBUG(lock, "sending request");
 232         rc = ptlrpc_queue_wait(req);
 233         rc = ptlrpc_check_status(req, rc);
 234
 235         if (rc != ELDLM_OK) {
 236                 LASSERT(!is_replay);
 237                 LDLM_DEBUG(lock, "client-side enqueue END (%s)",
 238                            rc == ELDLM_LOCK_ABORTED ? "ABORTED" : "FAILED");
 239                 ldlm_lock_decref(lockh, mode);
 240                 /* FIXME: if we've already received a completion AST, this will
 241                  * LBUG! */
 242                 ldlm_lock_destroy(lock);
 243                 GOTO(out, rc);
 244         }
 245
 246         reply = lustre_msg_buf(req->rq_repmsg, 0);
 247         memcpy(&lock->l_remote_handle, &reply->lock_handle,
 248                sizeof(lock->l_remote_handle));
 249         *flags = reply->lock_flags;
 250
 251         CDEBUG(D_INFO, "local: %p, remote: %p, flags: %d\n", lock,
 252                (void *)(unsigned long)reply->lock_handle.addr, *flags);
 253         if (type == LDLM_EXTENT) {
 254                 CDEBUG(D_INFO, "requested extent: "LPU64" -> "LPU64", got "
 255                        "extent "LPU64" -> "LPU64"\n",
 256                        body->lock_desc.l_extent.start,
 257                        body->lock_desc.l_extent.end,
 258                        reply->lock_extent.start, reply->lock_extent.end);
 259                 cookie = &reply->lock_extent; /* FIXME bug 267 */
 260                 cookielen = sizeof(reply->lock_extent);
 261         }
 262
 263         /* If enqueue returned a blocked lock but the completion handler has
 264          * already run, then it fixed up the resource and we don't need to do it
 265          * again. */
 266         if ((*flags) & LDLM_FL_LOCK_CHANGED) {
 267                 int newmode = reply->lock_mode;
 268                 LASSERT(!is_replay);
 269                 if (newmode && newmode != lock->l_req_mode) {
 270                         LDLM_DEBUG(lock, "server returned different mode %s",
 271                                    ldlm_lockname[newmode]);
 272                         lock->l_req_mode = newmode;
 273                 }
 274
 275                 if (reply->lock_resource_name[0] !=
 276                     lock->l_resource->lr_name[0]) {
 277                         CDEBUG(D_INFO, "remote intent success, locking %ld "
 278                                "instead of %ld\n",
 279                                (long)reply->lock_resource_name[0],
 280                                (long)lock->l_resource->lr_name[0]);
 281
 282                         ldlm_lock_change_resource(lock,
 283                                                   reply->lock_resource_name);
 284                         if (lock->l_resource == NULL) {
 285                                 LBUG();
 286                                 RETURN(-ENOMEM);
 287                         }
 288                         LDLM_DEBUG(lock, "client-side enqueue, new resource");
 289                 }
 290         }
 291
 292         if (!is_replay) {
 293                 rc = ldlm_lock_enqueue(lock, cookie, cookielen, flags,
 294                                        completion, blocking);
 295                 if (lock->l_completion_ast)
 296                         lock->l_completion_ast(lock, *flags);
 297         }
 298
 299         if (!req_passed_in)
 300                 ptlrpc_req_finished(req);
 301
 302         LDLM_DEBUG(lock, "client-side enqueue END");
 303         EXIT;
 304  out:
 305         LDLM_LOCK_PUT(lock);
 306  out_nolock:
 307         return rc;
 308 }
 309
 310 int ldlm_match_or_enqueue(struct lustre_handle *connh,
 311                           struct ptlrpc_request *req,
 312                           struct ldlm_namespace *ns,
 313                           struct lustre_handle *parent_lock_handle,
 314                           __u64 *res_id,
 315                           __u32 type,
 316                           void *cookie, int cookielen,
 317                           ldlm_mode_t mode,
 318                           int *flags,
 319                           ldlm_completion_callback completion,
 320                           ldlm_blocking_callback blocking,
 321                           void *data,
 322                           __u32 data_len,
 323                           struct lustre_handle *lockh)
 324 {
 325         int rc;
 326         ENTRY;
 327         rc = ldlm_lock_match(ns, res_id, type, cookie, cookielen, mode, lockh);
 328         if (rc == 0) {
 329                 rc = ldlm_cli_enqueue(connh, req, ns,
 330                                       parent_lock_handle, res_id, type, cookie,
 331                                       cookielen, mode, flags, completion,
 332                                       blocking, data, data_len, lockh);
 333                 if (rc != ELDLM_OK)
 334                         CERROR("ldlm_cli_enqueue: err: %d\n", rc);
 335                 RETURN(rc);
 336         } else
 337                 RETURN(0);
 338 }
 339
 340 int ldlm_cli_replay_enqueue(struct ldlm_lock *lock)
 341 {
 342         struct lustre_handle lockh;
 343         int flags = LDLM_FL_REPLAY;
 344         ldlm_lock2handle(lock, &lockh);
 345         return ldlm_cli_enqueue(lock->l_connh, NULL, NULL, NULL, NULL,
 346                                 lock->l_resource->lr_type, NULL, 0, -1, &flags,
 347                                 NULL, NULL, NULL, 0, &lockh);
 348 }
 349
 350 static int ldlm_cli_convert_local(struct ldlm_lock *lock, int new_mode,
 351                                   int *flags)
 352 {
 353         ENTRY;
 354         if (lock->l_resource->lr_namespace->ns_client) {
 355                 CERROR("Trying to cancel local lock\n");
 356                 LBUG();
 357         }
 358         LDLM_DEBUG(lock, "client-side local convert");
 359
 360         ldlm_lock_convert(lock, new_mode, flags);
 361         ldlm_reprocess_all(lock->l_resource);
 362
 363         LDLM_DEBUG(lock, "client-side local convert handler END");
 364         LDLM_LOCK_PUT(lock);
 365         RETURN(0);
 366 }
 367
 368 /* FIXME: one of ldlm_cli_convert or the server side should reject attempted
 369  * conversion of locks which are on the waiting or converting queue */
 370 int ldlm_cli_convert(struct lustre_handle *lockh, int new_mode, int *flags)
 371 {
 372         struct ldlm_request *body;
 373         struct lustre_handle *connh;
 374         struct ldlm_reply *reply;
 375         struct ldlm_lock *lock;
 376         struct ldlm_resource *res;
 377         struct ptlrpc_request *req;
 378         int rc, size = sizeof(*body);
 379         ENTRY;
 380
 381         lock = ldlm_handle2lock(lockh);
 382         if (!lock) {
 383                 LBUG();
 384                 RETURN(-EINVAL);
 385         }
 386         *flags = 0;
 387         connh = lock->l_connh;
 388
 389         if (!connh)
 390                 RETURN(ldlm_cli_convert_local(lock, new_mode, flags));
 391
 392         LDLM_DEBUG(lock, "client-side convert");
 393
 394         req = ptlrpc_prep_req(class_conn2cliimp(connh), LDLM_CONVERT, 1, &size,
 395                               NULL);
 396         if (!req)
 397                 GOTO(out, rc = -ENOMEM);
 398
 399         body = lustre_msg_buf(req->rq_reqmsg, 0);
 400         memcpy(&body->lock_handle1, &lock->l_remote_handle,
 401                sizeof(body->lock_handle1));
 402
 403         body->lock_desc.l_req_mode = new_mode;
 404         body->lock_flags = *flags;
 405
 406         size = sizeof(*reply);
 407         req->rq_replen = lustre_msg_size(1, &size);
 408
 409         rc = ptlrpc_queue_wait(req);
 410         rc = ptlrpc_check_status(req, rc);
 411         if (rc != ELDLM_OK)
 412                 GOTO(out, rc);
 413
 414         reply = lustre_msg_buf(req->rq_repmsg, 0);
 415         res = ldlm_lock_convert(lock, new_mode, &reply->lock_flags);
 416         if (res != NULL)
 417                 ldlm_reprocess_all(res);
 418         /* Go to sleep until the lock is granted. */
 419         /* FIXME: or cancelled. */
 420         if (lock->l_completion_ast)
 421                 lock->l_completion_ast(lock, LDLM_FL_WAIT_NOREPROC);
 422         EXIT;
 423  out:
 424         LDLM_LOCK_PUT(lock);
 425         ptlrpc_req_finished(req);
 426         return rc;
 427 }
 428
 429 int ldlm_cli_cancel(struct lustre_handle *lockh)
 430 {
 431         struct ptlrpc_request *req;
 432         struct ldlm_lock *lock;
 433         struct ldlm_request *body;
 434         int rc = 0, size = sizeof(*body);
 435         ENTRY;
 436
 437         lock = ldlm_handle2lock(lockh);
 438         if (!lock) {
 439                 /* It's possible that the decref that we did just before this
 440                  * cancel was the last reader/writer, and caused a cancel before
 441                  * we could call this function.  If we want to make this
 442                  * impossible (by adding a dec_and_cancel() or similar), then
 443                  * we can put the LBUG back. */
 444                 //LBUG();
 445                 RETURN(0);
 446         }
 447
 448         if (lock->l_connh) {
 449                 LDLM_DEBUG(lock, "client-side cancel");
 450                 /* Set this flag to prevent others from getting new references*/
 451                 l_lock(&lock->l_resource->lr_namespace->ns_lock);
 452                 lock->l_flags |= LDLM_FL_CBPENDING;
 453                 ldlm_cancel_callback(lock);
 454                 l_unlock(&lock->l_resource->lr_namespace->ns_lock);
 455
 456                 req = ptlrpc_prep_req(class_conn2cliimp(lock->l_connh),
 457                                       LDLM_CANCEL, 1, &size, NULL);
 458                 if (!req)
 459                         GOTO(out, rc = -ENOMEM);
 460
 461                 /* XXX FIXME bug 249 */
 462                 req->rq_request_portal = LDLM_CANCEL_REQUEST_PORTAL;
 463                 req->rq_reply_portal = LDLM_CANCEL_REPLY_PORTAL;
 464
 465                 body = lustre_msg_buf(req->rq_reqmsg, 0);
 466                 memcpy(&body->lock_handle1, &lock->l_remote_handle,
 467                        sizeof(body->lock_handle1));
 468
 469                 req->rq_replen = lustre_msg_size(0, NULL);
 470
 471                 rc = ptlrpc_queue_wait(req);
 472                 rc = ptlrpc_check_status(req, rc);
 473                 ptlrpc_req_finished(req);
 474                 if (rc != ELDLM_OK)
 475                         GOTO(out, rc);
 476
 477                 ldlm_lock_cancel(lock);
 478         } else {
 479                 LDLM_DEBUG(lock, "client-side local cancel");
 480                 if (lock->l_resource->lr_namespace->ns_client) {
 481                         CERROR("Trying to cancel local lock\n");
 482                         LBUG();
 483                 }
 484                 ldlm_lock_cancel(lock);
 485                 ldlm_reprocess_all(lock->l_resource);
 486                 LDLM_DEBUG(lock, "client-side local cancel handler END");
 487         }
 488
 489         EXIT;
 490  out:
 491         LDLM_LOCK_PUT(lock);
 492         return rc;
 493 }
 494
 495 int ldlm_cancel_lru(struct ldlm_namespace *ns)
 496 {
 497         struct list_head *tmp, *next, list = LIST_HEAD_INIT(list);
 498         int count, rc = 0;
 499         struct ldlm_ast_work *w;
 500         ENTRY;
 501
 502         l_lock(&ns->ns_lock);
 503         count = ns->ns_nr_unused - ns->ns_max_unused;
 504
 505         if (count <= 0) {
 506                 l_unlock(&ns->ns_lock);
 507                 RETURN(0);
 508         }
 509
 510         list_for_each_safe(tmp, next, &ns->ns_unused_list) {
 511                 struct ldlm_lock *lock;
 512                 lock = list_entry(tmp, struct ldlm_lock, l_lru);
 513
 514                 LASSERT(!lock->l_readers && !lock->l_writers);
 515
 516                 /* Setting the CBPENDING flag is a little misleading, but
 517                  * prevents an important race; namely, once CBPENDING is set,
 518                  * the lock can accumulate no more readers/writers.  Since
 519                  * readers and writers are already zero here, ldlm_lock_decref
 520                  * won't see this flag and call l_blocking_ast */
 521                 lock->l_flags |= LDLM_FL_CBPENDING;
 522
 523                 OBD_ALLOC(w, sizeof(*w));
 524                 LASSERT(w);
 525
 526                 w->w_lock = LDLM_LOCK_GET(lock);
 527                 list_add(&w->w_list, &list);
 528                 list_del_init(&lock->l_lru);
 529
 530                 if (--count == 0)
 531                         break;
 532         }
 533         l_unlock(&ns->ns_lock);
 534
 535         list_for_each_safe(tmp, next, &list) {
 536                 struct lustre_handle lockh;
 537                 int rc;
 538                 w = list_entry(tmp, struct ldlm_ast_work, w_list);
 539
 540                 ldlm_lock2handle(w->w_lock, &lockh);
 541                 rc = ldlm_cli_cancel(&lockh);
 542                 if (rc != ELDLM_OK)
 543                         CDEBUG(D_INFO, "ldlm_cli_cancel: %d\n", rc);
 544
 545                 list_del(&w->w_list);
 546                 LDLM_LOCK_PUT(w->w_lock);
 547                 OBD_FREE(w, sizeof(*w));
 548         }
 549
 550         RETURN(rc);
 551 }
 552
 553 int ldlm_cli_cancel_unused_resource(struct ldlm_namespace *ns,
 554                                     __u64 *res_id, int flags)
 555 {
 556         struct ldlm_resource *res;
 557         struct list_head *tmp, *next, list = LIST_HEAD_INIT(list);
 558         struct ldlm_ast_work *w;
 559         ENTRY;
 560
 561         if ((flags & LDLM_FL_REDUCE) &&
 562             ns->ns_max_unused > ns->ns_nr_unused)
 563                 RETURN(0);
 564
 565         res = ldlm_resource_get(ns, NULL, res_id, 0, 0);
 566         if (res == NULL) {
 567                 /* This is not a problem. */
 568                 CDEBUG(D_INFO, "No resource "LPU64"\n", res_id[0]);
 569                 RETURN(0);
 570         }
 571
 572         l_lock(&ns->ns_lock);
 573         list_for_each(tmp, &res->lr_granted) {
 574                 struct ldlm_lock *lock;
 575                 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
 576
 577                 if (lock->l_readers || lock->l_writers)
 578                         continue;
 579
 580                 /* See CBPENDING comment in ldlm_cancel_lru */
 581                 lock->l_flags |= LDLM_FL_CBPENDING;
 582
 583                 OBD_ALLOC(w, sizeof(*w));
 584                 LASSERT(w);
 585
 586                 w->w_lock = LDLM_LOCK_GET(lock);
 587                 list_add(&w->w_list, &list);
 588                 if ((flags & LDLM_FL_REDUCE) &&
 589                     ns->ns_max_unused > ns->ns_nr_unused)
 590                         break;
 591         }
 592         l_unlock(&ns->ns_lock);
 593
 594         list_for_each_safe(tmp, next, &list) {
 595                 struct lustre_handle lockh;
 596                 int rc;
 597                 w = list_entry(tmp, struct ldlm_ast_work, w_list);
 598
 599                 /* Prevent the cancel callback from being called by setting
 600                  * LDLM_FL_CANCEL in the lock.  Very sneaky. -p */
 601                 if (flags & LDLM_FL_NO_CALLBACK)
 602                         w->w_lock->l_flags |= LDLM_FL_CANCEL;
 603
 604                 if (flags & LDLM_FL_LOCAL_ONLY) {
 605                         ldlm_lock_cancel(w->w_lock);
 606                 } else {
 607                         ldlm_lock2handle(w->w_lock, &lockh);
 608                         rc = ldlm_cli_cancel(&lockh);
 609                         if (rc != ELDLM_OK)
 610                                 CERROR("ldlm_cli_cancel: %d\n", rc);
 611                 }
 612                 list_del(&w->w_list);
 613                 LDLM_LOCK_PUT(w->w_lock);
 614                 OBD_FREE(w, sizeof(*w));
 615         }
 616
 617         ldlm_resource_put(res);
 618
 619         RETURN(0);
 620 }
 621
 622 /* Cancel all locks on a namespace (or a specific resource, if given) that have
 623  * 0 readers/writers.
 624  *
 625  * If 'local_only' is true, throw the locks away without trying to notify the
 626  * server. */
 627 int ldlm_cli_cancel_unused(struct ldlm_namespace *ns, __u64 *res_id,
 628                            int flags)
 629 {
 630         int i;
 631
 632         if (res_id)
 633                 RETURN(ldlm_cli_cancel_unused_resource(ns, res_id, flags));
 634
 635         l_lock(&ns->ns_lock);
 636         for (i = 0; i < RES_HASH_SIZE; i++) {
 637                 struct list_head *tmp, *pos;
 638                 list_for_each_safe(tmp, pos, &(ns->ns_hash[i])) {
 639                         int rc;
 640                         struct ldlm_resource *res;
 641                         res = list_entry(tmp, struct ldlm_resource, lr_hash);
 642                         ldlm_resource_getref(res);
 643
 644                         rc = ldlm_cli_cancel_unused_resource(ns, res->lr_name,
 645                                                              flags);
 646
 647                         if (rc)
 648                                 CERROR("cancel_unused_res ("LPU64"): %d\n",
 649                                        res->lr_name[0], rc);
 650                         ldlm_resource_put(res);
 651                 }
 652         }
 653         l_unlock(&ns->ns_lock);
 654
 655         return ELDLM_OK;
 656 }