fs/ocfs2/dlm/dlmunlock.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * dlmunlock.c
   5  *
   6  * underlying calls for unlocking locks
   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 #include "cluster/heartbeat.h"
  44 #include "cluster/nodemanager.h"
  45 #include "cluster/tcp.h"
  46
  47 #include "dlmapi.h"
  48 #include "dlmcommon.h"
  49
  50 #define MLOG_MASK_PREFIX ML_DLM
  51 #include "cluster/masklog.h"
  52
  53 #define DLM_UNLOCK_FREE_LOCK           0x00000001
  54 #define DLM_UNLOCK_CALL_AST            0x00000002
  55 #define DLM_UNLOCK_REMOVE_LOCK         0x00000004
  56 #define DLM_UNLOCK_REGRANT_LOCK        0x00000008
  57 #define DLM_UNLOCK_CLEAR_CONVERT_TYPE  0x00000010
  58
  59
  60 static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
  61                                               struct dlm_lock_resource *res,
  62                                               struct dlm_lock *lock,
  63                                               struct dlm_lockstatus *lksb,
  64                                               int *actions);
  65 static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
  66                                               struct dlm_lock_resource *res,
  67                                               struct dlm_lock *lock,
  68                                               struct dlm_lockstatus *lksb,
  69                                               int *actions);
  70
  71 static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
  72                                                  struct dlm_lock_resource *res,
  73                                                  struct dlm_lock *lock,
  74                                                  struct dlm_lockstatus *lksb,
  75                                                  int flags,
  76                                                  u8 owner);
  77
  78
  79 /*
  80  * according to the spec:
  81  * http://opendlm.sourceforge.net/cvsmirror/opendlm/docs/dlmbook_final.pdf
  82  *
  83  *  flags & LKM_CANCEL != 0: must be converting or blocked
  84  *  flags & LKM_CANCEL == 0: must be granted
  85  *
  86  * So to unlock a converting lock, you must first cancel the
  87  * convert (passing LKM_CANCEL in flags), then call the unlock
  88  * again (with no LKM_CANCEL in flags).
  89  */
  90
  91
  92 /*
  93  * locking:
  94  *   caller needs:  none
  95  *   taken:         res->spinlock and lock->spinlock taken and dropped
  96  *   held on exit:  none
  97  * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
  98  * all callers should have taken an extra ref on lock coming in
  99  */
 100 static enum dlm_status dlmunlock_common(struct dlm_ctxt *dlm,
 101                                         struct dlm_lock_resource *res,
 102                                         struct dlm_lock *lock,
 103                                         struct dlm_lockstatus *lksb,
 104                                         int flags, int *call_ast,
 105                                         int master_node)
 106 {
 107         enum dlm_status status;
 108         int actions = 0;
 109         int in_use;
 110         u8 owner;
 111
 112         mlog(0, "master_node = %d, valblk = %d\n", master_node,
 113              flags & LKM_VALBLK);
 114
 115         if (master_node)
 116                 BUG_ON(res->owner != dlm->node_num);
 117         else
 118                 BUG_ON(res->owner == dlm->node_num);
 119
 120         spin_lock(&dlm->spinlock);
 121         /* We want to be sure that we're not freeing a lock
 122          * that still has AST's pending... */
 123         in_use = !list_empty(&lock->ast_list);
 124         spin_unlock(&dlm->spinlock);
 125         if (in_use) {
 126                mlog(ML_ERROR, "lockres %.*s: Someone is calling dlmunlock "
 127                     "while waiting for an ast!", res->lockname.len,
 128                     res->lockname.name);
 129                 return DLM_BADPARAM;
 130         }
 131
 132         spin_lock(&res->spinlock);
 133         if (res->state & DLM_LOCK_RES_IN_PROGRESS) {
 134                 if (master_node) {
 135                         mlog(ML_ERROR, "lockres in progress!\n");
 136                         spin_unlock(&res->spinlock);
 137                         return DLM_FORWARD;
 138                 }
 139                 /* ok for this to sleep if not in a network handler */
 140                 __dlm_wait_on_lockres(res);
 141                 res->state |= DLM_LOCK_RES_IN_PROGRESS;
 142         }
 143         spin_lock(&lock->spinlock);
 144
 145         if (res->state & DLM_LOCK_RES_RECOVERING) {
 146                 status = DLM_RECOVERING;
 147                 goto leave;
 148         }
 149
 150
 151         /* see above for what the spec says about
 152          * LKM_CANCEL and the lock queue state */
 153         if (flags & LKM_CANCEL)
 154                 status = dlm_get_cancel_actions(dlm, res, lock, lksb, &actions);
 155         else
 156                 status = dlm_get_unlock_actions(dlm, res, lock, lksb, &actions);
 157
 158         if (status != DLM_NORMAL)
 159                 goto leave;
 160
 161         /* By now this has been masked out of cancel requests. */
 162         if (flags & LKM_VALBLK) {
 163                 /* make the final update to the lvb */
 164                 if (master_node)
 165                         memcpy(res->lvb, lksb->lvb, DLM_LVB_LEN);
 166                 else
 167                         flags |= LKM_PUT_LVB; /* let the send function
 168                                                * handle it. */
 169         }
 170
 171         if (!master_node) {
 172                 owner = res->owner;
 173                 /* drop locks and send message */
 174                 if (flags & LKM_CANCEL)
 175                         lock->cancel_pending = 1;
 176                 else
 177                         lock->unlock_pending = 1;
 178                 spin_unlock(&lock->spinlock);
 179                 spin_unlock(&res->spinlock);
 180                 status = dlm_send_remote_unlock_request(dlm, res, lock, lksb,
 181                                                         flags, owner);
 182                 spin_lock(&res->spinlock);
 183                 spin_lock(&lock->spinlock);
 184                 /* if the master told us the lock was already granted,
 185                  * let the ast handle all of these actions */
 186                 if (status == DLM_NORMAL &&
 187                     lksb->status == DLM_CANCELGRANT) {
 188                         actions &= ~(DLM_UNLOCK_REMOVE_LOCK|
 189                                      DLM_UNLOCK_REGRANT_LOCK|
 190                                      DLM_UNLOCK_CLEAR_CONVERT_TYPE);
 191                 }
 192                 if (flags & LKM_CANCEL)
 193                         lock->cancel_pending = 0;
 194                 else
 195                         lock->unlock_pending = 0;
 196
 197         }
 198
 199         /* get an extra ref on lock.  if we are just switching
 200          * lists here, we dont want the lock to go away. */
 201         dlm_lock_get(lock);
 202
 203         if (actions & DLM_UNLOCK_REMOVE_LOCK) {
 204                 list_del_init(&lock->list);
 205                 dlm_lock_put(lock);
 206         }
 207         if (actions & DLM_UNLOCK_REGRANT_LOCK) {
 208                 dlm_lock_get(lock);
 209                 list_add_tail(&lock->list, &res->granted);
 210         }
 211         if (actions & DLM_UNLOCK_CLEAR_CONVERT_TYPE) {
 212                 mlog(0, "clearing convert_type at %smaster node\n",
 213                      master_node ? "" : "non-");
 214                 lock->ml.convert_type = LKM_IVMODE;
 215         }
 216
 217         /* remove the extra ref on lock */
 218         dlm_lock_put(lock);
 219
 220 leave:
 221         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
 222         if (!dlm_lock_on_list(&res->converting, lock))
 223                 BUG_ON(lock->ml.convert_type != LKM_IVMODE);
 224         else
 225                 BUG_ON(lock->ml.convert_type == LKM_IVMODE);
 226         spin_unlock(&lock->spinlock);
 227         spin_unlock(&res->spinlock);
 228         wake_up(&res->wq);
 229
 230         /* let the caller's final dlm_lock_put handle the actual kfree */
 231         if (actions & DLM_UNLOCK_FREE_LOCK) {
 232                 /* this should always be coupled with list removal */
 233                 BUG_ON(!(actions & DLM_UNLOCK_REMOVE_LOCK));
 234                 mlog(0, "lock %"MLFu64" should be gone now! refs=%d\n",
 235                      lock->ml.cookie, atomic_read(&lock->lock_refs.refcount)-1);
 236                 dlm_lock_put(lock);
 237         }
 238         if (actions & DLM_UNLOCK_CALL_AST)
 239                 *call_ast = 1;
 240
 241         /* if cancel or unlock succeeded, lvb work is done */
 242         if (status == DLM_NORMAL)
 243                 lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);
 244
 245         return status;
 246 }
 247
 248 void dlm_commit_pending_unlock(struct dlm_lock_resource *res,
 249                                struct dlm_lock *lock)
 250 {
 251         /* leave DLM_LKSB_PUT_LVB on the lksb so any final
 252          * update of the lvb will be sent to the new master */
 253         list_del_init(&lock->list);
 254 }
 255
 256 void dlm_commit_pending_cancel(struct dlm_lock_resource *res,
 257                                struct dlm_lock *lock)
 258 {
 259         list_del_init(&lock->list);
 260         list_add_tail(&lock->list, &res->granted);
 261         lock->ml.convert_type = LKM_IVMODE;
 262 }
 263
 264
 265 static inline enum dlm_status dlmunlock_master(struct dlm_ctxt *dlm,
 266                                           struct dlm_lock_resource *res,
 267                                           struct dlm_lock *lock,
 268                                           struct dlm_lockstatus *lksb,
 269                                           int flags,
 270                                           int *call_ast)
 271 {
 272         return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 1);
 273 }
 274
 275 static inline enum dlm_status dlmunlock_remote(struct dlm_ctxt *dlm,
 276                                           struct dlm_lock_resource *res,
 277                                           struct dlm_lock *lock,
 278                                           struct dlm_lockstatus *lksb,
 279                                           int flags, int *call_ast)
 280 {
 281         return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 0);
 282 }
 283
 284 /*
 285  * locking:
 286  *   caller needs:  none
 287  *   taken:         none
 288  *   held on exit:  none
 289  * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
 290  */
 291 static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
 292                                                  struct dlm_lock_resource *res,
 293                                                  struct dlm_lock *lock,
 294                                                  struct dlm_lockstatus *lksb,
 295                                                  int flags,
 296                                                  u8 owner)
 297 {
 298         struct dlm_unlock_lock unlock;
 299         int tmpret;
 300         enum dlm_status ret;
 301         int status = 0;
 302         struct kvec vec[2];
 303         size_t veclen = 1;
 304
 305         mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
 306
 307         memset(&unlock, 0, sizeof(unlock));
 308         unlock.node_idx = dlm->node_num;
 309         unlock.flags = cpu_to_be32(flags);
 310         unlock.cookie = lock->ml.cookie;
 311         unlock.namelen = res->lockname.len;
 312         memcpy(unlock.name, res->lockname.name, unlock.namelen);
 313
 314         vec[0].iov_len = sizeof(struct dlm_unlock_lock);
 315         vec[0].iov_base = &unlock;
 316
 317         if (flags & LKM_PUT_LVB) {
 318                 /* extra data to send if we are updating lvb */
 319                 vec[1].iov_len = DLM_LVB_LEN;
 320                 vec[1].iov_base = lock->lksb->lvb;
 321                 veclen++;
 322         }
 323
 324         tmpret = o2net_send_message_vec(DLM_UNLOCK_LOCK_MSG, dlm->key,
 325                                         vec, veclen, owner, &status);
 326         if (tmpret >= 0) {
 327                 // successfully sent and received
 328                 if (status == DLM_CANCELGRANT)
 329                         ret = DLM_NORMAL;
 330                 else if (status == DLM_FORWARD) {
 331                         mlog(0, "master was in-progress.  retry\n");
 332                         ret = DLM_FORWARD;
 333                 } else
 334                         ret = status;
 335                 lksb->status = status;
 336         } else {
 337                 mlog_errno(tmpret);
 338                 if (dlm_is_host_down(tmpret)) {
 339                         /* NOTE: this seems strange, but it is what we want.
 340                          * when the master goes down during a cancel or
 341                          * unlock, the recovery code completes the operation
 342                          * as if the master had not died, then passes the
 343                          * updated state to the recovery master.  this thread
 344                          * just needs to finish out the operation and call
 345                          * the unlockast. */
 346                         ret = DLM_NORMAL;
 347                 } else {
 348                         /* something bad.  this will BUG in ocfs2 */
 349                         ret = dlm_err_to_dlm_status(tmpret);
 350                 }
 351                 lksb->status = ret;
 352         }
 353
 354         return ret;
 355 }
 356
 357 /*
 358  * locking:
 359  *   caller needs:  none
 360  *   taken:         takes and drops res->spinlock
 361  *   held on exit:  none
 362  * returns: DLM_NORMAL, DLM_BADARGS, DLM_IVLOCKID,
 363  *          return value from dlmunlock_master
 364  */
 365 int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data)
 366 {
 367         struct dlm_ctxt *dlm = data;
 368         struct dlm_unlock_lock *unlock = (struct dlm_unlock_lock *)msg->buf;
 369         struct dlm_lock_resource *res = NULL;
 370         struct list_head *iter;
 371         struct dlm_lock *lock = NULL;
 372         enum dlm_status status = DLM_NORMAL;
 373         int found = 0, i;
 374         struct dlm_lockstatus *lksb = NULL;
 375         int ignore;
 376         u32 flags;
 377         struct list_head *queue;
 378
 379         flags = be32_to_cpu(unlock->flags);
 380
 381         if (flags & LKM_GET_LVB) {
 382                 mlog(ML_ERROR, "bad args!  GET_LVB specified on unlock!\n");
 383                 return DLM_BADARGS;
 384         }
 385
 386         if ((flags & (LKM_PUT_LVB|LKM_CANCEL)) == (LKM_PUT_LVB|LKM_CANCEL)) {
 387                 mlog(ML_ERROR, "bad args!  cannot modify lvb on a CANCEL "
 388                      "request!\n");
 389                 return DLM_BADARGS;
 390         }
 391
 392         if (unlock->namelen > DLM_LOCKID_NAME_MAX) {
 393                 mlog(ML_ERROR, "Invalid name length in unlock handler!\n");
 394                 return DLM_IVBUFLEN;
 395         }
 396
 397         if (!dlm_grab(dlm))
 398                 return DLM_REJECTED;
 399
 400         mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
 401                         "Domain %s not fully joined!\n", dlm->name);
 402
 403         mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" : "none");
 404
 405         res = dlm_lookup_lockres(dlm, unlock->name, unlock->namelen);
 406         if (!res) {
 407                 /* We assume here that a no lock resource simply means
 408                  * it was migrated away and destroyed before the other
 409                  * node could detect it. */
 410                 mlog(0, "returning DLM_FORWARD -- res no longer exists\n");
 411                 status = DLM_FORWARD;
 412                 goto not_found;
 413         }
 414
 415         queue=&res->granted;
 416         found = 0;
 417         spin_lock(&res->spinlock);
 418         if (res->state & DLM_LOCK_RES_RECOVERING) {
 419                 spin_unlock(&res->spinlock);
 420                 mlog(0, "returning DLM_RECOVERING\n");
 421                 status = DLM_RECOVERING;
 422                 goto leave;
 423         }
 424
 425         if (res->state & DLM_LOCK_RES_MIGRATING) {
 426                 spin_unlock(&res->spinlock);
 427                 mlog(0, "returning DLM_MIGRATING\n");
 428                 status = DLM_MIGRATING;
 429                 goto leave;
 430         }
 431
 432         if (res->owner != dlm->node_num) {
 433                 spin_unlock(&res->spinlock);
 434                 mlog(0, "returning DLM_FORWARD -- not master\n");
 435                 status = DLM_FORWARD;
 436                 goto leave;
 437         }
 438
 439         for (i=0; i<3; i++) {
 440                 list_for_each(iter, queue) {
 441                         lock = list_entry(iter, struct dlm_lock, list);
 442                         if (lock->ml.cookie == unlock->cookie &&
 443                             lock->ml.node == unlock->node_idx) {
 444                                 dlm_lock_get(lock);
 445                                 found = 1;
 446                                 break;
 447                         }
 448                 }
 449                 if (found)
 450                         break;
 451                 /* scan granted -> converting -> blocked queues */
 452                 queue++;
 453         }
 454         spin_unlock(&res->spinlock);
 455         if (!found) {
 456                 status = DLM_IVLOCKID;
 457                 goto not_found;
 458         }
 459
 460         /* lock was found on queue */
 461         lksb = lock->lksb;
 462         /* unlockast only called on originating node */
 463         if (flags & LKM_PUT_LVB) {
 464                 lksb->flags |= DLM_LKSB_PUT_LVB;
 465                 memcpy(&lksb->lvb[0], &unlock->lvb[0], DLM_LVB_LEN);
 466         }
 467
 468         /* if this is in-progress, propagate the DLM_FORWARD
 469          * all the way back out */
 470         status = dlmunlock_master(dlm, res, lock, lksb, flags, &ignore);
 471         if (status == DLM_FORWARD)
 472                 mlog(0, "lockres is in progress\n");
 473
 474         if (flags & LKM_PUT_LVB)
 475                 lksb->flags &= ~DLM_LKSB_PUT_LVB;
 476
 477         dlm_lockres_calc_usage(dlm, res);
 478         dlm_kick_thread(dlm, res);
 479
 480 not_found:
 481         if (!found)
 482                 mlog(ML_ERROR, "failed to find lock to unlock! "
 483                                "cookie=%"MLFu64"\n",
 484                      unlock->cookie);
 485         else {
 486                 /* send the lksb->status back to the other node */
 487                 status = lksb->status;
 488                 dlm_lock_put(lock);
 489         }
 490
 491 leave:
 492         if (res)
 493                 dlm_lockres_put(res);
 494
 495         dlm_put(dlm);
 496
 497         return status;
 498 }
 499
 500
 501 static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
 502                                               struct dlm_lock_resource *res,
 503                                               struct dlm_lock *lock,
 504                                               struct dlm_lockstatus *lksb,
 505                                               int *actions)
 506 {
 507         enum dlm_status status;
 508
 509         if (dlm_lock_on_list(&res->blocked, lock)) {
 510                 /* cancel this outright */
 511                 lksb->status = DLM_NORMAL;
 512                 status = DLM_NORMAL;
 513                 *actions = (DLM_UNLOCK_CALL_AST |
 514                             DLM_UNLOCK_REMOVE_LOCK);
 515         } else if (dlm_lock_on_list(&res->converting, lock)) {
 516                 /* cancel the request, put back on granted */
 517                 lksb->status = DLM_NORMAL;
 518                 status = DLM_NORMAL;
 519                 *actions = (DLM_UNLOCK_CALL_AST |
 520                             DLM_UNLOCK_REMOVE_LOCK |
 521                             DLM_UNLOCK_REGRANT_LOCK |
 522                             DLM_UNLOCK_CLEAR_CONVERT_TYPE);
 523         } else if (dlm_lock_on_list(&res->granted, lock)) {
 524                 /* too late, already granted.  DLM_CANCELGRANT */
 525                 lksb->status = DLM_CANCELGRANT;
 526                 status = DLM_NORMAL;
 527                 *actions = DLM_UNLOCK_CALL_AST;
 528         } else {
 529                 mlog(ML_ERROR, "lock to cancel is not on any list!\n");
 530                 lksb->status = DLM_IVLOCKID;
 531                 status = DLM_IVLOCKID;
 532                 *actions = 0;
 533         }
 534         return status;
 535 }
 536
 537 static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
 538                                               struct dlm_lock_resource *res,
 539                                               struct dlm_lock *lock,
 540                                               struct dlm_lockstatus *lksb,
 541                                               int *actions)
 542 {
 543         enum dlm_status status;
 544
 545         /* unlock request */
 546         if (!dlm_lock_on_list(&res->granted, lock)) {
 547                 lksb->status = DLM_DENIED;
 548                 status = DLM_DENIED;
 549                 dlm_error(status);
 550                 *actions = 0;
 551         } else {
 552                 /* unlock granted lock */
 553                 lksb->status = DLM_NORMAL;
 554                 status = DLM_NORMAL;
 555                 *actions = (DLM_UNLOCK_FREE_LOCK |
 556                             DLM_UNLOCK_CALL_AST |
 557                             DLM_UNLOCK_REMOVE_LOCK);
 558         }
 559         return status;
 560 }
 561
 562 /* there seems to be no point in doing this async
 563  * since (even for the remote case) there is really
 564  * no work to queue up... so just do it and fire the
 565  * unlockast by hand when done... */
 566 enum dlm_status dlmunlock(struct dlm_ctxt *dlm, struct dlm_lockstatus *lksb,
 567                           int flags, dlm_astunlockfunc_t *unlockast, void *data)
 568 {
 569         enum dlm_status status;
 570         struct dlm_lock_resource *res;
 571         struct dlm_lock *lock = NULL;
 572         int call_ast, is_master;
 573
 574         mlog_entry_void();
 575
 576         if (!lksb) {
 577                 dlm_error(DLM_BADARGS);
 578                 return DLM_BADARGS;
 579         }
 580
 581         if (flags & ~(LKM_CANCEL | LKM_VALBLK | LKM_INVVALBLK)) {
 582                 dlm_error(DLM_BADPARAM);
 583                 return DLM_BADPARAM;
 584         }
 585
 586         if ((flags & (LKM_VALBLK | LKM_CANCEL)) == (LKM_VALBLK | LKM_CANCEL)) {
 587                 mlog(0, "VALBLK given with CANCEL: ignoring VALBLK\n");
 588                 flags &= ~LKM_VALBLK;
 589         }
 590
 591         if (!lksb->lockid || !lksb->lockid->lockres) {
 592                 dlm_error(DLM_BADPARAM);
 593                 return DLM_BADPARAM;
 594         }
 595
 596         lock = lksb->lockid;
 597         BUG_ON(!lock);
 598         dlm_lock_get(lock);
 599
 600         res = lock->lockres;
 601         BUG_ON(!res);
 602         dlm_lockres_get(res);
 603 retry:
 604         call_ast = 0;
 605         /* need to retry up here because owner may have changed */
 606         mlog(0, "lock=%p res=%p\n", lock, res);
 607
 608         spin_lock(&res->spinlock);
 609         is_master = (res->owner == dlm->node_num);
 610         spin_unlock(&res->spinlock);
 611
 612         if (is_master) {
 613                 status = dlmunlock_master(dlm, res, lock, lksb, flags,
 614                                           &call_ast);
 615                 mlog(0, "done calling dlmunlock_master: returned %d, "
 616                      "call_ast is %d\n", status, call_ast);
 617         } else {
 618                 status = dlmunlock_remote(dlm, res, lock, lksb, flags,
 619                                           &call_ast);
 620                 mlog(0, "done calling dlmunlock_remote: returned %d, "
 621                      "call_ast is %d\n", status, call_ast);
 622         }
 623
 624         if (status == DLM_RECOVERING ||
 625             status == DLM_MIGRATING ||
 626             status == DLM_FORWARD) {
 627                 /* We want to go away for a tiny bit to allow recovery
 628                  * / migration to complete on this resource. I don't
 629                  * know of any wait queue we could sleep on as this
 630                  * may be happening on another node. Perhaps the
 631                  * proper solution is to queue up requests on the
 632                  * other end? */
 633
 634                 /* do we want to yield(); ?? */
 635                 msleep(50);
 636
 637                 mlog(0, "retrying unlock due to pending recovery/"
 638                      "migration/in-progress\n");
 639                 goto retry;
 640         }
 641
 642         if (call_ast) {
 643                 mlog(0, "calling unlockast(%p, %d)\n", data, lksb->status);
 644                 if (is_master) {
 645                         /* it is possible that there is one last bast
 646                          * pending.  make sure it is flushed, then
 647                          * call the unlockast.
 648                          * not an issue if this is a mastered remotely,
 649                          * since this lock has been removed from the
 650                          * lockres queues and cannot be found. */
 651                         dlm_kick_thread(dlm, NULL);
 652                         wait_event(dlm->ast_wq,
 653                                    dlm_lock_basts_flushed(dlm, lock));
 654                 }
 655                 (*unlockast)(data, lksb->status);
 656         }
 657
 658         if (status == DLM_NORMAL) {
 659                 mlog(0, "kicking the thread\n");
 660                 dlm_kick_thread(dlm, res);
 661         } else
 662                 dlm_error(status);
 663
 664         dlm_lockres_calc_usage(dlm, res);
 665         dlm_lockres_put(res);
 666         dlm_lock_put(lock);
 667
 668         mlog(0, "returning status=%d!\n", status);
 669         return status;
 670 }
 671 EXPORT_SYMBOL_GPL(dlmunlock);
 672