git.oblomov.eu Git - linux-2.6/blob - fs/ocfs2/dlm/dlmlock.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * dlmlock.c
   5  *
   6  * underlying calls for lock creation
   7  *
   8  * Copyright (C) 2004 Oracle.  All rights reserved.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2 of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public
  21  * License along with this program; if not, write to the
  22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23  * Boston, MA 021110-1307, USA.
  24  *
  25  */
  26
  27
  28 #include <linux/module.h>
  29 #include <linux/fs.h>
  30 #include <linux/types.h>
  31 #include <linux/slab.h>
  32 #include <linux/highmem.h>
  33 #include <linux/utsname.h>
  34 #include <linux/init.h>
  35 #include <linux/sysctl.h>
  36 #include <linux/random.h>
  37 #include <linux/blkdev.h>
  38 #include <linux/socket.h>
  39 #include <linux/inet.h>
  40 #include <linux/spinlock.h>
  41 #include <linux/delay.h>
  42
  43
  44 #include "cluster/heartbeat.h"
  45 #include "cluster/nodemanager.h"
  46 #include "cluster/tcp.h"
  47
  48 #include "dlmapi.h"
  49 #include "dlmcommon.h"
  50
  51 #include "dlmconvert.h"
  52
  53 #define MLOG_MASK_PREFIX ML_DLM
  54 #include "cluster/masklog.h"
  55
  56 static spinlock_t dlm_cookie_lock = SPIN_LOCK_UNLOCKED;
  57 static u64 dlm_next_cookie = 1;
  58
  59 static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
  60                                                struct dlm_lock_resource *res,
  61                                                struct dlm_lock *lock, int flags);
  62 static void dlm_init_lock(struct dlm_lock *newlock, int type,
  63                           u8 node, u64 cookie);
  64 static void dlm_lock_release(struct kref *kref);
  65 static void dlm_lock_detach_lockres(struct dlm_lock *lock);
  66
  67 /* Tell us whether we can grant a new lock request.
  68  * locking:
  69  *   caller needs:  res->spinlock
  70  *   taken:         none
  71  *   held on exit:  none
  72  * returns: 1 if the lock can be granted, 0 otherwise.
  73  */
  74 static int dlm_can_grant_new_lock(struct dlm_lock_resource *res,
  75                                   struct dlm_lock *lock)
  76 {
  77         struct list_head *iter;
  78         struct dlm_lock *tmplock;
  79
  80         list_for_each(iter, &res->granted) {
  81                 tmplock = list_entry(iter, struct dlm_lock, list);
  82
  83                 if (!dlm_lock_compatible(tmplock->ml.type, lock->ml.type))
  84                         return 0;
  85         }
  86
  87         list_for_each(iter, &res->converting) {
  88                 tmplock = list_entry(iter, struct dlm_lock, list);
  89
  90                 if (!dlm_lock_compatible(tmplock->ml.type, lock->ml.type))
  91                         return 0;
  92         }
  93
  94         return 1;
  95 }
  96
  97 /* performs lock creation at the lockres master site
  98  * locking:
  99  *   caller needs:  none
 100  *   taken:         takes and drops res->spinlock
 101  *   held on exit:  none
 102  * returns: DLM_NORMAL, DLM_NOTQUEUED
 103  */
 104 static enum dlm_status dlmlock_master(struct dlm_ctxt *dlm,
 105                                       struct dlm_lock_resource *res,
 106                                       struct dlm_lock *lock, int flags)
 107 {
 108         int call_ast = 0, kick_thread = 0;
 109         enum dlm_status status = DLM_NORMAL;
 110
 111         mlog_entry("type=%d\n", lock->ml.type);
 112
 113         spin_lock(&res->spinlock);
 114         /* if called from dlm_create_lock_handler, need to
 115          * ensure it will not sleep in dlm_wait_on_lockres */
 116         status = __dlm_lockres_state_to_status(res);
 117         if (status != DLM_NORMAL &&
 118             lock->ml.node != dlm->node_num) {
 119                 /* erf.  state changed after lock was dropped. */
 120                 spin_unlock(&res->spinlock);
 121                 dlm_error(status);
 122                 return status;
 123         }
 124         __dlm_wait_on_lockres(res);
 125         __dlm_lockres_reserve_ast(res);
 126
 127         if (dlm_can_grant_new_lock(res, lock)) {
 128                 mlog(0, "I can grant this lock right away\n");
 129                 /* got it right away */
 130                 lock->lksb->status = DLM_NORMAL;
 131                 status = DLM_NORMAL;
 132                 dlm_lock_get(lock);
 133                 list_add_tail(&lock->list, &res->granted);
 134
 135                 /* for the recovery lock, we can't allow the ast
 136                  * to be queued since the dlmthread is already
 137                  * frozen.  but the recovery lock is always locked
 138                  * with LKM_NOQUEUE so we do not need the ast in
 139                  * this special case */
 140                 if (!dlm_is_recovery_lock(res->lockname.name,
 141                                           res->lockname.len)) {
 142                         kick_thread = 1;
 143                         call_ast = 1;
 144                 }
 145         } else {
 146                 /* for NOQUEUE request, unless we get the
 147                  * lock right away, return DLM_NOTQUEUED */
 148                 if (flags & LKM_NOQUEUE)
 149                         status = DLM_NOTQUEUED;
 150                 else {
 151                         dlm_lock_get(lock);
 152                         list_add_tail(&lock->list, &res->blocked);
 153                         kick_thread = 1;
 154                 }
 155         }
 156
 157         spin_unlock(&res->spinlock);
 158         wake_up(&res->wq);
 159
 160         /* either queue the ast or release it */
 161         if (call_ast)
 162                 dlm_queue_ast(dlm, lock);
 163         else
 164                 dlm_lockres_release_ast(dlm, res);
 165
 166         dlm_lockres_calc_usage(dlm, res);
 167         if (kick_thread)
 168                 dlm_kick_thread(dlm, res);
 169
 170         return status;
 171 }
 172
 173 void dlm_revert_pending_lock(struct dlm_lock_resource *res,
 174                              struct dlm_lock *lock)
 175 {
 176         /* remove from local queue if it failed */
 177         list_del_init(&lock->list);
 178         lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
 179 }
 180
 181
 182 /*
 183  * locking:
 184  *   caller needs:  none
 185  *   taken:         takes and drops res->spinlock
 186  *   held on exit:  none
 187  * returns: DLM_DENIED, DLM_RECOVERING, or net status
 188  */
 189 static enum dlm_status dlmlock_remote(struct dlm_ctxt *dlm,
 190                                       struct dlm_lock_resource *res,
 191                                       struct dlm_lock *lock, int flags)
 192 {
 193         enum dlm_status status = DLM_DENIED;
 194
 195         mlog_entry("type=%d\n", lock->ml.type);
 196         mlog(0, "lockres %.*s, flags = 0x%x\n", res->lockname.len,
 197              res->lockname.name, flags);
 198
 199         spin_lock(&res->spinlock);
 200
 201         /* will exit this call with spinlock held */
 202         __dlm_wait_on_lockres(res);
 203         res->state |= DLM_LOCK_RES_IN_PROGRESS;
 204
 205         /* add lock to local (secondary) queue */
 206         dlm_lock_get(lock);
 207         list_add_tail(&lock->list, &res->blocked);
 208         lock->lock_pending = 1;
 209         spin_unlock(&res->spinlock);
 210
 211         /* spec seems to say that you will get DLM_NORMAL when the lock
 212          * has been queued, meaning we need to wait for a reply here. */
 213         status = dlm_send_remote_lock_request(dlm, res, lock, flags);
 214
 215         spin_lock(&res->spinlock);
 216         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
 217         lock->lock_pending = 0;
 218         if (status != DLM_NORMAL) {
 219                 if (status != DLM_NOTQUEUED)
 220                         dlm_error(status);
 221                 dlm_revert_pending_lock(res, lock);
 222                 dlm_lock_put(lock);
 223         }
 224         spin_unlock(&res->spinlock);
 225
 226         dlm_lockres_calc_usage(dlm, res);
 227
 228         wake_up(&res->wq);
 229         return status;
 230 }
 231
 232
 233 /* for remote lock creation.
 234  * locking:
 235  *   caller needs:  none, but need res->state & DLM_LOCK_RES_IN_PROGRESS
 236  *   taken:         none
 237  *   held on exit:  none
 238  * returns: DLM_NOLOCKMGR, or net status
 239  */
 240 static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
 241                                                struct dlm_lock_resource *res,
 242                                                struct dlm_lock *lock, int flags)
 243 {
 244         struct dlm_create_lock create;
 245         int tmpret, status = 0;
 246         enum dlm_status ret;
 247
 248         mlog_entry_void();
 249
 250         memset(&create, 0, sizeof(create));
 251         create.node_idx = dlm->node_num;
 252         create.requested_type = lock->ml.type;
 253         create.cookie = lock->ml.cookie;
 254         create.namelen = res->lockname.len;
 255         create.flags = cpu_to_be32(flags);
 256         memcpy(create.name, res->lockname.name, create.namelen);
 257
 258         tmpret = o2net_send_message(DLM_CREATE_LOCK_MSG, dlm->key, &create,
 259                                     sizeof(create), res->owner, &status);
 260         if (tmpret >= 0) {
 261                 // successfully sent and received
 262                 ret = status;  // this is already a dlm_status
 263         } else {
 264                 mlog_errno(tmpret);
 265                 if (dlm_is_host_down(tmpret)) {
 266                         ret = DLM_RECOVERING;
 267                         mlog(0, "node %u died so returning DLM_RECOVERING "
 268                              "from lock message!\n", res->owner);
 269                 } else {
 270                         ret = dlm_err_to_dlm_status(tmpret);
 271                 }
 272         }
 273
 274         return ret;
 275 }
 276
 277 void dlm_lock_get(struct dlm_lock *lock)
 278 {
 279         kref_get(&lock->lock_refs);
 280 }
 281
 282 void dlm_lock_put(struct dlm_lock *lock)
 283 {
 284         kref_put(&lock->lock_refs, dlm_lock_release);
 285 }
 286
 287 static void dlm_lock_release(struct kref *kref)
 288 {
 289         struct dlm_lock *lock;
 290
 291         lock = container_of(kref, struct dlm_lock, lock_refs);
 292
 293         BUG_ON(!list_empty(&lock->list));
 294         BUG_ON(!list_empty(&lock->ast_list));
 295         BUG_ON(!list_empty(&lock->bast_list));
 296         BUG_ON(lock->ast_pending);
 297         BUG_ON(lock->bast_pending);
 298
 299         dlm_lock_detach_lockres(lock);
 300
 301         if (lock->lksb_kernel_allocated) {
 302                 mlog(0, "freeing kernel-allocated lksb\n");
 303                 kfree(lock->lksb);
 304         }
 305         kfree(lock);
 306 }
 307
 308 /* associate a lock with it's lockres, getting a ref on the lockres */
 309 void dlm_lock_attach_lockres(struct dlm_lock *lock,
 310                              struct dlm_lock_resource *res)
 311 {
 312         dlm_lockres_get(res);
 313         lock->lockres = res;
 314 }
 315
 316 /* drop ref on lockres, if there is still one associated with lock */
 317 static void dlm_lock_detach_lockres(struct dlm_lock *lock)
 318 {
 319         struct dlm_lock_resource *res;
 320
 321         res = lock->lockres;
 322         if (res) {
 323                 lock->lockres = NULL;
 324                 mlog(0, "removing lock's lockres reference\n");
 325                 dlm_lockres_put(res);
 326         }
 327 }
 328
 329 static void dlm_init_lock(struct dlm_lock *newlock, int type,
 330                           u8 node, u64 cookie)
 331 {
 332         INIT_LIST_HEAD(&newlock->list);
 333         INIT_LIST_HEAD(&newlock->ast_list);
 334         INIT_LIST_HEAD(&newlock->bast_list);
 335         spin_lock_init(&newlock->spinlock);
 336         newlock->ml.type = type;
 337         newlock->ml.convert_type = LKM_IVMODE;
 338         newlock->ml.highest_blocked = LKM_IVMODE;
 339         newlock->ml.node = node;
 340         newlock->ml.pad1 = 0;
 341         newlock->ml.list = 0;
 342         newlock->ml.flags = 0;
 343         newlock->ast = NULL;
 344         newlock->bast = NULL;
 345         newlock->astdata = NULL;
 346         newlock->ml.cookie = cpu_to_be64(cookie);
 347         newlock->ast_pending = 0;
 348         newlock->bast_pending = 0;
 349         newlock->convert_pending = 0;
 350         newlock->lock_pending = 0;
 351         newlock->unlock_pending = 0;
 352         newlock->cancel_pending = 0;
 353         newlock->lksb_kernel_allocated = 0;
 354
 355         kref_init(&newlock->lock_refs);
 356 }
 357
 358 struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
 359                                struct dlm_lockstatus *lksb)
 360 {
 361         struct dlm_lock *lock;
 362         int kernel_allocated = 0;
 363
 364         lock = kcalloc(1, sizeof(*lock), GFP_KERNEL);
 365         if (!lock)
 366                 return NULL;
 367
 368         if (!lksb) {
 369                 /* zero memory only if kernel-allocated */
 370                 lksb = kcalloc(1, sizeof(*lksb), GFP_KERNEL);
 371                 if (!lksb) {
 372                         kfree(lock);
 373                         return NULL;
 374                 }
 375                 kernel_allocated = 1;
 376         }
 377
 378         dlm_init_lock(lock, type, node, cookie);
 379         if (kernel_allocated)
 380                 lock->lksb_kernel_allocated = 1;
 381         lock->lksb = lksb;
 382         lksb->lockid = lock;
 383         return lock;
 384 }
 385
 386 /* handler for lock creation net message
 387  * locking:
 388  *   caller needs:  none
 389  *   taken:         takes and drops res->spinlock
 390  *   held on exit:  none
 391  * returns: DLM_NORMAL, DLM_SYSERR, DLM_IVLOCKID, DLM_NOTQUEUED
 392  */
 393 int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data)
 394 {
 395         struct dlm_ctxt *dlm = data;
 396         struct dlm_create_lock *create = (struct dlm_create_lock *)msg->buf;
 397         struct dlm_lock_resource *res = NULL;
 398         struct dlm_lock *newlock = NULL;
 399         struct dlm_lockstatus *lksb = NULL;
 400         enum dlm_status status = DLM_NORMAL;
 401         char *name;
 402         unsigned int namelen;
 403
 404         BUG_ON(!dlm);
 405
 406         mlog_entry_void();
 407
 408         if (!dlm_grab(dlm))
 409                 return DLM_REJECTED;
 410
 411         mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
 412                         "Domain %s not fully joined!\n", dlm->name);
 413
 414         name = create->name;
 415         namelen = create->namelen;
 416
 417         status = DLM_IVBUFLEN;
 418         if (namelen > DLM_LOCKID_NAME_MAX) {
 419                 dlm_error(status);
 420                 goto leave;
 421         }
 422
 423         status = DLM_SYSERR;
 424         newlock = dlm_new_lock(create->requested_type,
 425                                create->node_idx,
 426                                be64_to_cpu(create->cookie), NULL);
 427         if (!newlock) {
 428                 dlm_error(status);
 429                 goto leave;
 430         }
 431
 432         lksb = newlock->lksb;
 433
 434         if (be32_to_cpu(create->flags) & LKM_GET_LVB) {
 435                 lksb->flags |= DLM_LKSB_GET_LVB;
 436                 mlog(0, "set DLM_LKSB_GET_LVB flag\n");
 437         }
 438
 439         status = DLM_IVLOCKID;
 440         res = dlm_lookup_lockres(dlm, name, namelen);
 441         if (!res) {
 442                 dlm_error(status);
 443                 goto leave;
 444         }
 445
 446         spin_lock(&res->spinlock);
 447         status = __dlm_lockres_state_to_status(res);
 448         spin_unlock(&res->spinlock);
 449
 450         if (status != DLM_NORMAL) {
 451                 mlog(0, "lockres recovering/migrating/in-progress\n");
 452                 goto leave;
 453         }
 454
 455         dlm_lock_attach_lockres(newlock, res);
 456
 457         status = dlmlock_master(dlm, res, newlock, be32_to_cpu(create->flags));
 458 leave:
 459         if (status != DLM_NORMAL)
 460                 if (newlock)
 461                         dlm_lock_put(newlock);
 462
 463         if (res)
 464                 dlm_lockres_put(res);
 465
 466         dlm_put(dlm);
 467
 468         return status;
 469 }
 470
 471
 472 /* fetch next node-local (u8 nodenum + u56 cookie) into u64 */
 473 static inline void dlm_get_next_cookie(u8 node_num, u64 *cookie)
 474 {
 475         u64 tmpnode = node_num;
 476
 477         /* shift single byte of node num into top 8 bits */
 478         tmpnode <<= 56;
 479
 480         spin_lock(&dlm_cookie_lock);
 481         *cookie = (dlm_next_cookie | tmpnode);
 482         if (++dlm_next_cookie & 0xff00000000000000ull) {
 483                 mlog(0, "This node's cookie will now wrap!\n");
 484                 dlm_next_cookie = 1;
 485         }
 486         spin_unlock(&dlm_cookie_lock);
 487 }
 488
 489 enum dlm_status dlmlock(struct dlm_ctxt *dlm, int mode,
 490                         struct dlm_lockstatus *lksb, int flags,
 491                         const char *name, dlm_astlockfunc_t *ast, void *data,
 492                         dlm_bastlockfunc_t *bast)
 493 {
 494         enum dlm_status status;
 495         struct dlm_lock_resource *res = NULL;
 496         struct dlm_lock *lock = NULL;
 497         int convert = 0, recovery = 0;
 498
 499         /* yes this function is a mess.
 500          * TODO: clean this up.  lots of common code in the
 501          *       lock and convert paths, especially in the retry blocks */
 502         if (!lksb) {
 503                 dlm_error(DLM_BADARGS);
 504                 return DLM_BADARGS;
 505         }
 506
 507         status = DLM_BADPARAM;
 508         if (mode != LKM_EXMODE && mode != LKM_PRMODE && mode != LKM_NLMODE) {
 509                 dlm_error(status);
 510                 goto error;
 511         }
 512
 513         if (flags & ~LKM_VALID_FLAGS) {
 514                 dlm_error(status);
 515                 goto error;
 516         }
 517
 518         convert = (flags & LKM_CONVERT);
 519         recovery = (flags & LKM_RECOVERY);
 520
 521         if (recovery &&
 522             (!dlm_is_recovery_lock(name, strlen(name)) || convert) ) {
 523                 dlm_error(status);
 524                 goto error;
 525         }
 526         if (convert && (flags & LKM_LOCAL)) {
 527                 mlog(ML_ERROR, "strange LOCAL convert request!\n");
 528                 goto error;
 529         }
 530
 531         if (convert) {
 532                 /* CONVERT request */
 533
 534                 /* if converting, must pass in a valid dlm_lock */
 535                 lock = lksb->lockid;
 536                 if (!lock) {
 537                         mlog(ML_ERROR, "NULL lock pointer in convert "
 538                              "request\n");
 539                         goto error;
 540                 }
 541
 542                 res = lock->lockres;
 543                 if (!res) {
 544                         mlog(ML_ERROR, "NULL lockres pointer in convert "
 545                              "request\n");
 546                         goto error;
 547                 }
 548                 dlm_lockres_get(res);
 549
 550                 /* XXX: for ocfs2 purposes, the ast/bast/astdata/lksb are
 551                  * static after the original lock call.  convert requests will
 552                  * ensure that everything is the same, or return DLM_BADARGS.
 553                  * this means that DLM_DENIED_NOASTS will never be returned.
 554                  */
 555                 if (lock->lksb != lksb || lock->ast != ast ||
 556                     lock->bast != bast || lock->astdata != data) {
 557                         status = DLM_BADARGS;
 558                         mlog(ML_ERROR, "new args:  lksb=%p, ast=%p, bast=%p, "
 559                              "astdata=%p\n", lksb, ast, bast, data);
 560                         mlog(ML_ERROR, "orig args: lksb=%p, ast=%p, bast=%p, "
 561                              "astdata=%p\n", lock->lksb, lock->ast,
 562                              lock->bast, lock->astdata);
 563                         goto error;
 564                 }
 565 retry_convert:
 566                 dlm_wait_for_recovery(dlm);
 567
 568                 if (res->owner == dlm->node_num)
 569                         status = dlmconvert_master(dlm, res, lock, flags, mode);
 570                 else
 571                         status = dlmconvert_remote(dlm, res, lock, flags, mode);
 572                 if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
 573                     status == DLM_FORWARD) {
 574                         /* for now, see how this works without sleeping
 575                          * and just retry right away.  I suspect the reco
 576                          * or migration will complete fast enough that
 577                          * no waiting will be necessary */
 578                         mlog(0, "retrying convert with migration/recovery/"
 579                              "in-progress\n");
 580                         msleep(100);
 581                         goto retry_convert;
 582                 }
 583         } else {
 584                 u64 tmpcookie;
 585
 586                 /* LOCK request */
 587                 status = DLM_BADARGS;
 588                 if (!name) {
 589                         dlm_error(status);
 590                         goto error;
 591                 }
 592
 593                 status = DLM_IVBUFLEN;
 594                 if (strlen(name) > DLM_LOCKID_NAME_MAX || strlen(name) < 1) {
 595                         dlm_error(status);
 596                         goto error;
 597                 }
 598
 599                 dlm_get_next_cookie(dlm->node_num, &tmpcookie);
 600                 lock = dlm_new_lock(mode, dlm->node_num, tmpcookie, lksb);
 601                 if (!lock) {
 602                         dlm_error(status);
 603                         goto error;
 604                 }
 605
 606                 if (!recovery)
 607                         dlm_wait_for_recovery(dlm);
 608
 609                 /* find or create the lock resource */
 610                 res = dlm_get_lock_resource(dlm, name, flags);
 611                 if (!res) {
 612                         status = DLM_IVLOCKID;
 613                         dlm_error(status);
 614                         goto error;
 615                 }
 616
 617                 mlog(0, "type=%d, flags = 0x%x\n", mode, flags);
 618                 mlog(0, "creating lock: lock=%p res=%p\n", lock, res);
 619
 620                 dlm_lock_attach_lockres(lock, res);
 621                 lock->ast = ast;
 622                 lock->bast = bast;
 623                 lock->astdata = data;
 624
 625 retry_lock:
 626                 if (flags & LKM_VALBLK) {
 627                         mlog(0, "LKM_VALBLK passed by caller\n");
 628
 629                         /* LVB requests for non PR, PW or EX locks are
 630                          * ignored. */
 631                         if (mode < LKM_PRMODE)
 632                                 flags &= ~LKM_VALBLK;
 633                         else {
 634                                 flags |= LKM_GET_LVB;
 635                                 lock->lksb->flags |= DLM_LKSB_GET_LVB;
 636                         }
 637                 }
 638
 639                 if (res->owner == dlm->node_num)
 640                         status = dlmlock_master(dlm, res, lock, flags);
 641                 else
 642                         status = dlmlock_remote(dlm, res, lock, flags);
 643
 644                 if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
 645                     status == DLM_FORWARD) {
 646                         mlog(0, "retrying lock with migration/"
 647                              "recovery/in progress\n");
 648                         msleep(100);
 649                         dlm_wait_for_recovery(dlm);
 650                         goto retry_lock;
 651                 }
 652
 653                 if (status != DLM_NORMAL) {
 654                         lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
 655                         if (status != DLM_NOTQUEUED)
 656                                 dlm_error(status);
 657                         goto error;
 658                 }
 659         }
 660
 661 error:
 662         if (status != DLM_NORMAL) {
 663                 if (lock && !convert)
 664                         dlm_lock_put(lock);
 665                 // this is kind of unnecessary
 666                 lksb->status = status;
 667         }
 668
 669         /* put lockres ref from the convert path
 670          * or from dlm_get_lock_resource */
 671         if (res)
 672                 dlm_lockres_put(res);
 673
 674         return status;
 675 }
 676 EXPORT_SYMBOL_GPL(dlmlock);