Pull platform-drivers into test branch
[linux-2.6] / 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 && (status != DLM_CANCELGRANT || !master_node))
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_CANCELGRANT) {
187                         actions &= ~(DLM_UNLOCK_REMOVE_LOCK|
188                                      DLM_UNLOCK_REGRANT_LOCK|
189                                      DLM_UNLOCK_CLEAR_CONVERT_TYPE);
190                 } else if (status == DLM_RECOVERING || 
191                            status == DLM_MIGRATING || 
192                            status == DLM_FORWARD) {
193                         /* must clear the actions because this unlock
194                          * is about to be retried.  cannot free or do
195                          * any list manipulation. */
196                         mlog(0, "%s:%.*s: clearing actions, %s\n",
197                              dlm->name, res->lockname.len,
198                              res->lockname.name,
199                              status==DLM_RECOVERING?"recovering":
200                              (status==DLM_MIGRATING?"migrating":
201                               "forward"));
202                         actions = 0;
203                 }
204                 if (flags & LKM_CANCEL)
205                         lock->cancel_pending = 0;
206                 else
207                         lock->unlock_pending = 0;
208
209         }
210
211         /* get an extra ref on lock.  if we are just switching
212          * lists here, we dont want the lock to go away. */
213         dlm_lock_get(lock);
214
215         if (actions & DLM_UNLOCK_REMOVE_LOCK) {
216                 list_del_init(&lock->list);
217                 dlm_lock_put(lock);
218         }
219         if (actions & DLM_UNLOCK_REGRANT_LOCK) {
220                 dlm_lock_get(lock);
221                 list_add_tail(&lock->list, &res->granted);
222         }
223         if (actions & DLM_UNLOCK_CLEAR_CONVERT_TYPE) {
224                 mlog(0, "clearing convert_type at %smaster node\n",
225                      master_node ? "" : "non-");
226                 lock->ml.convert_type = LKM_IVMODE;
227         }
228
229         /* remove the extra ref on lock */
230         dlm_lock_put(lock);
231
232 leave:
233         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
234         if (!dlm_lock_on_list(&res->converting, lock))
235                 BUG_ON(lock->ml.convert_type != LKM_IVMODE);
236         else
237                 BUG_ON(lock->ml.convert_type == LKM_IVMODE);
238         spin_unlock(&lock->spinlock);
239         spin_unlock(&res->spinlock);
240         wake_up(&res->wq);
241
242         /* let the caller's final dlm_lock_put handle the actual kfree */
243         if (actions & DLM_UNLOCK_FREE_LOCK) {
244                 /* this should always be coupled with list removal */
245                 BUG_ON(!(actions & DLM_UNLOCK_REMOVE_LOCK));
246                 mlog(0, "lock %u:%llu should be gone now! refs=%d\n",
247                      dlm_get_lock_cookie_node(lock->ml.cookie),
248                      dlm_get_lock_cookie_seq(lock->ml.cookie),
249                      atomic_read(&lock->lock_refs.refcount)-1);
250                 dlm_lock_put(lock);
251         }
252         if (actions & DLM_UNLOCK_CALL_AST)
253                 *call_ast = 1;
254
255         /* if cancel or unlock succeeded, lvb work is done */
256         if (status == DLM_NORMAL)
257                 lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);
258
259         return status;
260 }
261
262 void dlm_commit_pending_unlock(struct dlm_lock_resource *res,
263                                struct dlm_lock *lock)
264 {
265         /* leave DLM_LKSB_PUT_LVB on the lksb so any final
266          * update of the lvb will be sent to the new master */
267         list_del_init(&lock->list);
268 }
269
270 void dlm_commit_pending_cancel(struct dlm_lock_resource *res,
271                                struct dlm_lock *lock)
272 {
273         list_move_tail(&lock->list, &res->granted);
274         lock->ml.convert_type = LKM_IVMODE;
275 }
276
277
278 static inline enum dlm_status dlmunlock_master(struct dlm_ctxt *dlm,
279                                           struct dlm_lock_resource *res,
280                                           struct dlm_lock *lock,
281                                           struct dlm_lockstatus *lksb,
282                                           int flags,
283                                           int *call_ast)
284 {
285         return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 1);
286 }
287
288 static inline enum dlm_status dlmunlock_remote(struct dlm_ctxt *dlm,
289                                           struct dlm_lock_resource *res,
290                                           struct dlm_lock *lock,
291                                           struct dlm_lockstatus *lksb,
292                                           int flags, int *call_ast)
293 {
294         return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 0);
295 }
296
297 /*
298  * locking:
299  *   caller needs:  none
300  *   taken:         none
301  *   held on exit:  none
302  * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
303  */
304 static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
305                                                  struct dlm_lock_resource *res,
306                                                  struct dlm_lock *lock,
307                                                  struct dlm_lockstatus *lksb,
308                                                  int flags,
309                                                  u8 owner)
310 {
311         struct dlm_unlock_lock unlock;
312         int tmpret;
313         enum dlm_status ret;
314         int status = 0;
315         struct kvec vec[2];
316         size_t veclen = 1;
317
318         mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
319
320         if (owner == dlm->node_num) {
321                 /* ended up trying to contact ourself.  this means
322                  * that the lockres had been remote but became local
323                  * via a migration.  just retry it, now as local */
324                 mlog(0, "%s:%.*s: this node became the master due to a "
325                      "migration, re-evaluate now\n", dlm->name,
326                      res->lockname.len, res->lockname.name);
327                 return DLM_FORWARD;
328         }
329
330         memset(&unlock, 0, sizeof(unlock));
331         unlock.node_idx = dlm->node_num;
332         unlock.flags = cpu_to_be32(flags);
333         unlock.cookie = lock->ml.cookie;
334         unlock.namelen = res->lockname.len;
335         memcpy(unlock.name, res->lockname.name, unlock.namelen);
336
337         vec[0].iov_len = sizeof(struct dlm_unlock_lock);
338         vec[0].iov_base = &unlock;
339
340         if (flags & LKM_PUT_LVB) {
341                 /* extra data to send if we are updating lvb */
342                 vec[1].iov_len = DLM_LVB_LEN;
343                 vec[1].iov_base = lock->lksb->lvb;
344                 veclen++;
345         }
346
347         tmpret = o2net_send_message_vec(DLM_UNLOCK_LOCK_MSG, dlm->key,
348                                         vec, veclen, owner, &status);
349         if (tmpret >= 0) {
350                 // successfully sent and received
351                 if (status == DLM_FORWARD)
352                         mlog(0, "master was in-progress.  retry\n");
353                 ret = status;
354         } else {
355                 mlog_errno(tmpret);
356                 if (dlm_is_host_down(tmpret)) {
357                         /* NOTE: this seems strange, but it is what we want.
358                          * when the master goes down during a cancel or
359                          * unlock, the recovery code completes the operation
360                          * as if the master had not died, then passes the
361                          * updated state to the recovery master.  this thread
362                          * just needs to finish out the operation and call
363                          * the unlockast. */
364                         ret = DLM_NORMAL;
365                 } else {
366                         /* something bad.  this will BUG in ocfs2 */
367                         ret = dlm_err_to_dlm_status(tmpret);
368                 }
369         }
370
371         return ret;
372 }
373
374 /*
375  * locking:
376  *   caller needs:  none
377  *   taken:         takes and drops res->spinlock
378  *   held on exit:  none
379  * returns: DLM_NORMAL, DLM_BADARGS, DLM_IVLOCKID,
380  *          return value from dlmunlock_master
381  */
382 int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data)
383 {
384         struct dlm_ctxt *dlm = data;
385         struct dlm_unlock_lock *unlock = (struct dlm_unlock_lock *)msg->buf;
386         struct dlm_lock_resource *res = NULL;
387         struct list_head *iter;
388         struct dlm_lock *lock = NULL;
389         enum dlm_status status = DLM_NORMAL;
390         int found = 0, i;
391         struct dlm_lockstatus *lksb = NULL;
392         int ignore;
393         u32 flags;
394         struct list_head *queue;
395
396         flags = be32_to_cpu(unlock->flags);
397
398         if (flags & LKM_GET_LVB) {
399                 mlog(ML_ERROR, "bad args!  GET_LVB specified on unlock!\n");
400                 return DLM_BADARGS;
401         }
402
403         if ((flags & (LKM_PUT_LVB|LKM_CANCEL)) == (LKM_PUT_LVB|LKM_CANCEL)) {
404                 mlog(ML_ERROR, "bad args!  cannot modify lvb on a CANCEL "
405                      "request!\n");
406                 return DLM_BADARGS;
407         }
408
409         if (unlock->namelen > DLM_LOCKID_NAME_MAX) {
410                 mlog(ML_ERROR, "Invalid name length in unlock handler!\n");
411                 return DLM_IVBUFLEN;
412         }
413
414         if (!dlm_grab(dlm))
415                 return DLM_REJECTED;
416
417         mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
418                         "Domain %s not fully joined!\n", dlm->name);
419
420         mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" : "none");
421
422         res = dlm_lookup_lockres(dlm, unlock->name, unlock->namelen);
423         if (!res) {
424                 /* We assume here that a no lock resource simply means
425                  * it was migrated away and destroyed before the other
426                  * node could detect it. */
427                 mlog(0, "returning DLM_FORWARD -- res no longer exists\n");
428                 status = DLM_FORWARD;
429                 goto not_found;
430         }
431
432         queue=&res->granted;
433         found = 0;
434         spin_lock(&res->spinlock);
435         if (res->state & DLM_LOCK_RES_RECOVERING) {
436                 spin_unlock(&res->spinlock);
437                 mlog(0, "returning DLM_RECOVERING\n");
438                 status = DLM_RECOVERING;
439                 goto leave;
440         }
441
442         if (res->state & DLM_LOCK_RES_MIGRATING) {
443                 spin_unlock(&res->spinlock);
444                 mlog(0, "returning DLM_MIGRATING\n");
445                 status = DLM_MIGRATING;
446                 goto leave;
447         }
448
449         if (res->owner != dlm->node_num) {
450                 spin_unlock(&res->spinlock);
451                 mlog(0, "returning DLM_FORWARD -- not master\n");
452                 status = DLM_FORWARD;
453                 goto leave;
454         }
455
456         for (i=0; i<3; i++) {
457                 list_for_each(iter, queue) {
458                         lock = list_entry(iter, struct dlm_lock, list);
459                         if (lock->ml.cookie == unlock->cookie &&
460                             lock->ml.node == unlock->node_idx) {
461                                 dlm_lock_get(lock);
462                                 found = 1;
463                                 break;
464                         }
465                 }
466                 if (found)
467                         break;
468                 /* scan granted -> converting -> blocked queues */
469                 queue++;
470         }
471         spin_unlock(&res->spinlock);
472         if (!found) {
473                 status = DLM_IVLOCKID;
474                 goto not_found;
475         }
476
477         /* lock was found on queue */
478         lksb = lock->lksb;
479         if (flags & (LKM_VALBLK|LKM_PUT_LVB) &&
480             lock->ml.type != LKM_EXMODE)
481                 flags &= ~(LKM_VALBLK|LKM_PUT_LVB);
482
483         /* unlockast only called on originating node */
484         if (flags & LKM_PUT_LVB) {
485                 lksb->flags |= DLM_LKSB_PUT_LVB;
486                 memcpy(&lksb->lvb[0], &unlock->lvb[0], DLM_LVB_LEN);
487         }
488
489         /* if this is in-progress, propagate the DLM_FORWARD
490          * all the way back out */
491         status = dlmunlock_master(dlm, res, lock, lksb, flags, &ignore);
492         if (status == DLM_FORWARD)
493                 mlog(0, "lockres is in progress\n");
494
495         if (flags & LKM_PUT_LVB)
496                 lksb->flags &= ~DLM_LKSB_PUT_LVB;
497
498         dlm_lockres_calc_usage(dlm, res);
499         dlm_kick_thread(dlm, res);
500
501 not_found:
502         if (!found)
503                 mlog(ML_ERROR, "failed to find lock to unlock! "
504                                "cookie=%u:%llu\n",
505                                dlm_get_lock_cookie_node(unlock->cookie),
506                                dlm_get_lock_cookie_seq(unlock->cookie));
507         else
508                 dlm_lock_put(lock);
509
510 leave:
511         if (res)
512                 dlm_lockres_put(res);
513
514         dlm_put(dlm);
515
516         return status;
517 }
518
519
520 static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
521                                               struct dlm_lock_resource *res,
522                                               struct dlm_lock *lock,
523                                               struct dlm_lockstatus *lksb,
524                                               int *actions)
525 {
526         enum dlm_status status;
527
528         if (dlm_lock_on_list(&res->blocked, lock)) {
529                 /* cancel this outright */
530                 status = DLM_NORMAL;
531                 *actions = (DLM_UNLOCK_CALL_AST |
532                             DLM_UNLOCK_REMOVE_LOCK);
533         } else if (dlm_lock_on_list(&res->converting, lock)) {
534                 /* cancel the request, put back on granted */
535                 status = DLM_NORMAL;
536                 *actions = (DLM_UNLOCK_CALL_AST |
537                             DLM_UNLOCK_REMOVE_LOCK |
538                             DLM_UNLOCK_REGRANT_LOCK |
539                             DLM_UNLOCK_CLEAR_CONVERT_TYPE);
540         } else if (dlm_lock_on_list(&res->granted, lock)) {
541                 /* too late, already granted. */
542                 status = DLM_CANCELGRANT;
543                 *actions = DLM_UNLOCK_CALL_AST;
544         } else {
545                 mlog(ML_ERROR, "lock to cancel is not on any list!\n");
546                 status = DLM_IVLOCKID;
547                 *actions = 0;
548         }
549         return status;
550 }
551
552 static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
553                                               struct dlm_lock_resource *res,
554                                               struct dlm_lock *lock,
555                                               struct dlm_lockstatus *lksb,
556                                               int *actions)
557 {
558         enum dlm_status status;
559
560         /* unlock request */
561         if (!dlm_lock_on_list(&res->granted, lock)) {
562                 status = DLM_DENIED;
563                 dlm_error(status);
564                 *actions = 0;
565         } else {
566                 /* unlock granted lock */
567                 status = DLM_NORMAL;
568                 *actions = (DLM_UNLOCK_FREE_LOCK |
569                             DLM_UNLOCK_CALL_AST |
570                             DLM_UNLOCK_REMOVE_LOCK);
571         }
572         return status;
573 }
574
575 /* there seems to be no point in doing this async
576  * since (even for the remote case) there is really
577  * no work to queue up... so just do it and fire the
578  * unlockast by hand when done... */
579 enum dlm_status dlmunlock(struct dlm_ctxt *dlm, struct dlm_lockstatus *lksb,
580                           int flags, dlm_astunlockfunc_t *unlockast, void *data)
581 {
582         enum dlm_status status;
583         struct dlm_lock_resource *res;
584         struct dlm_lock *lock = NULL;
585         int call_ast, is_master;
586
587         mlog_entry_void();
588
589         if (!lksb) {
590                 dlm_error(DLM_BADARGS);
591                 return DLM_BADARGS;
592         }
593
594         if (flags & ~(LKM_CANCEL | LKM_VALBLK | LKM_INVVALBLK)) {
595                 dlm_error(DLM_BADPARAM);
596                 return DLM_BADPARAM;
597         }
598
599         if ((flags & (LKM_VALBLK | LKM_CANCEL)) == (LKM_VALBLK | LKM_CANCEL)) {
600                 mlog(0, "VALBLK given with CANCEL: ignoring VALBLK\n");
601                 flags &= ~LKM_VALBLK;
602         }
603
604         if (!lksb->lockid || !lksb->lockid->lockres) {
605                 dlm_error(DLM_BADPARAM);
606                 return DLM_BADPARAM;
607         }
608
609         lock = lksb->lockid;
610         BUG_ON(!lock);
611         dlm_lock_get(lock);
612
613         res = lock->lockres;
614         BUG_ON(!res);
615         dlm_lockres_get(res);
616 retry:
617         call_ast = 0;
618         /* need to retry up here because owner may have changed */
619         mlog(0, "lock=%p res=%p\n", lock, res);
620
621         spin_lock(&res->spinlock);
622         is_master = (res->owner == dlm->node_num);
623         if (flags & LKM_VALBLK && lock->ml.type != LKM_EXMODE)
624                 flags &= ~LKM_VALBLK;
625         spin_unlock(&res->spinlock);
626
627         if (is_master) {
628                 status = dlmunlock_master(dlm, res, lock, lksb, flags,
629                                           &call_ast);
630                 mlog(0, "done calling dlmunlock_master: returned %d, "
631                      "call_ast is %d\n", status, call_ast);
632         } else {
633                 status = dlmunlock_remote(dlm, res, lock, lksb, flags,
634                                           &call_ast);
635                 mlog(0, "done calling dlmunlock_remote: returned %d, "
636                      "call_ast is %d\n", status, call_ast);
637         }
638
639         if (status == DLM_RECOVERING ||
640             status == DLM_MIGRATING ||
641             status == DLM_FORWARD) {
642                 /* We want to go away for a tiny bit to allow recovery
643                  * / migration to complete on this resource. I don't
644                  * know of any wait queue we could sleep on as this
645                  * may be happening on another node. Perhaps the
646                  * proper solution is to queue up requests on the
647                  * other end? */
648
649                 /* do we want to yield(); ?? */
650                 msleep(50);
651
652                 mlog(0, "retrying unlock due to pending recovery/"
653                      "migration/in-progress\n");
654                 goto retry;
655         }
656
657         if (call_ast) {
658                 mlog(0, "calling unlockast(%p, %d)\n", data, status);
659                 if (is_master) {
660                         /* it is possible that there is one last bast 
661                          * pending.  make sure it is flushed, then
662                          * call the unlockast.
663                          * not an issue if this is a mastered remotely,
664                          * since this lock has been removed from the
665                          * lockres queues and cannot be found. */
666                         dlm_kick_thread(dlm, NULL);
667                         wait_event(dlm->ast_wq, 
668                                    dlm_lock_basts_flushed(dlm, lock));
669                 }
670                 (*unlockast)(data, status);
671         }
672
673         if (status == DLM_CANCELGRANT)
674                 status = DLM_NORMAL;
675
676         if (status == DLM_NORMAL) {
677                 mlog(0, "kicking the thread\n");
678                 dlm_kick_thread(dlm, res);
679         } else
680                 dlm_error(status);
681
682         dlm_lockres_calc_usage(dlm, res);
683         dlm_lockres_put(res);
684         dlm_lock_put(lock);
685
686         mlog(0, "returning status=%d!\n", status);
687         return status;
688 }
689 EXPORT_SYMBOL_GPL(dlmunlock);
690