xref: /linux/fs/ocfs2/dlm/dlmunlock.c (revision 60e13231561b3a4c5269bfa1ef6c0569ad6f28ec)
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/highmem.h>
32 #include <linux/init.h>
33 #include <linux/sysctl.h>
34 #include <linux/random.h>
35 #include <linux/blkdev.h>
36 #include <linux/socket.h>
37 #include <linux/inet.h>
38 #include <linux/spinlock.h>
39 #include <linux/delay.h>
40 
41 #include "cluster/heartbeat.h"
42 #include "cluster/nodemanager.h"
43 #include "cluster/tcp.h"
44 
45 #include "dlmapi.h"
46 #include "dlmcommon.h"
47 
48 #define MLOG_MASK_PREFIX ML_DLM
49 #include "cluster/masklog.h"
50 
51 #define DLM_UNLOCK_FREE_LOCK           0x00000001
52 #define DLM_UNLOCK_CALL_AST            0x00000002
53 #define DLM_UNLOCK_REMOVE_LOCK         0x00000004
54 #define DLM_UNLOCK_REGRANT_LOCK        0x00000008
55 #define DLM_UNLOCK_CLEAR_CONVERT_TYPE  0x00000010
56 
57 
58 static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
59 					      struct dlm_lock_resource *res,
60 					      struct dlm_lock *lock,
61 					      struct dlm_lockstatus *lksb,
62 					      int *actions);
63 static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
64 					      struct dlm_lock_resource *res,
65 					      struct dlm_lock *lock,
66 					      struct dlm_lockstatus *lksb,
67 					      int *actions);
68 
69 static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
70 						 struct dlm_lock_resource *res,
71 						 struct dlm_lock *lock,
72 						 struct dlm_lockstatus *lksb,
73 						 int flags,
74 						 u8 owner);
75 
76 
77 /*
78  * according to the spec:
79  * http://opendlm.sourceforge.net/cvsmirror/opendlm/docs/dlmbook_final.pdf
80  *
81  *  flags & LKM_CANCEL != 0: must be converting or blocked
82  *  flags & LKM_CANCEL == 0: must be granted
83  *
84  * So to unlock a converting lock, you must first cancel the
85  * convert (passing LKM_CANCEL in flags), then call the unlock
86  * again (with no LKM_CANCEL in flags).
87  */
88 
89 
90 /*
91  * locking:
92  *   caller needs:  none
93  *   taken:         res->spinlock and lock->spinlock taken and dropped
94  *   held on exit:  none
95  * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
96  * all callers should have taken an extra ref on lock coming in
97  */
98 static enum dlm_status dlmunlock_common(struct dlm_ctxt *dlm,
99 					struct dlm_lock_resource *res,
100 					struct dlm_lock *lock,
101 					struct dlm_lockstatus *lksb,
102 					int flags, int *call_ast,
103 					int master_node)
104 {
105 	enum dlm_status status;
106 	int actions = 0;
107 	int in_use;
108         u8 owner;
109 
110 	mlog(0, "master_node = %d, valblk = %d\n", master_node,
111 	     flags & LKM_VALBLK);
112 
113 	if (master_node)
114 		BUG_ON(res->owner != dlm->node_num);
115 	else
116 		BUG_ON(res->owner == dlm->node_num);
117 
118 	spin_lock(&dlm->ast_lock);
119 	/* We want to be sure that we're not freeing a lock
120 	 * that still has AST's pending... */
121 	in_use = !list_empty(&lock->ast_list);
122 	spin_unlock(&dlm->ast_lock);
123 	if (in_use && !(flags & LKM_CANCEL)) {
124 	       mlog(ML_ERROR, "lockres %.*s: Someone is calling dlmunlock "
125 		    "while waiting for an ast!", res->lockname.len,
126 		    res->lockname.name);
127 		return DLM_BADPARAM;
128 	}
129 
130 	spin_lock(&res->spinlock);
131 	if (res->state & DLM_LOCK_RES_IN_PROGRESS) {
132 		if (master_node && !(flags & LKM_CANCEL)) {
133 			mlog(ML_ERROR, "lockres in progress!\n");
134 			spin_unlock(&res->spinlock);
135 			return DLM_FORWARD;
136 		}
137 		/* ok for this to sleep if not in a network handler */
138 		__dlm_wait_on_lockres(res);
139 		res->state |= DLM_LOCK_RES_IN_PROGRESS;
140 	}
141 	spin_lock(&lock->spinlock);
142 
143 	if (res->state & DLM_LOCK_RES_RECOVERING) {
144 		status = DLM_RECOVERING;
145 		goto leave;
146 	}
147 
148 	if (res->state & DLM_LOCK_RES_MIGRATING) {
149 		status = DLM_MIGRATING;
150 		goto leave;
151 	}
152 
153 	/* see above for what the spec says about
154 	 * LKM_CANCEL and the lock queue state */
155 	if (flags & LKM_CANCEL)
156 		status = dlm_get_cancel_actions(dlm, res, lock, lksb, &actions);
157 	else
158 		status = dlm_get_unlock_actions(dlm, res, lock, lksb, &actions);
159 
160 	if (status != DLM_NORMAL && (status != DLM_CANCELGRANT || !master_node))
161 		goto leave;
162 
163 	/* By now this has been masked out of cancel requests. */
164 	if (flags & LKM_VALBLK) {
165 		/* make the final update to the lvb */
166 		if (master_node)
167 			memcpy(res->lvb, lksb->lvb, DLM_LVB_LEN);
168 		else
169 			flags |= LKM_PUT_LVB; /* let the send function
170 					       * handle it. */
171 	}
172 
173 	if (!master_node) {
174 		owner = res->owner;
175 		/* drop locks and send message */
176 		if (flags & LKM_CANCEL)
177 			lock->cancel_pending = 1;
178 		else
179 			lock->unlock_pending = 1;
180 		spin_unlock(&lock->spinlock);
181 		spin_unlock(&res->spinlock);
182 		status = dlm_send_remote_unlock_request(dlm, res, lock, lksb,
183 							flags, owner);
184 		spin_lock(&res->spinlock);
185 		spin_lock(&lock->spinlock);
186 		/* if the master told us the lock was already granted,
187 		 * let the ast handle all of these actions */
188 		if (status == DLM_CANCELGRANT) {
189 			actions &= ~(DLM_UNLOCK_REMOVE_LOCK|
190 				     DLM_UNLOCK_REGRANT_LOCK|
191 				     DLM_UNLOCK_CLEAR_CONVERT_TYPE);
192 		} else if (status == DLM_RECOVERING ||
193 			   status == DLM_MIGRATING ||
194 			   status == DLM_FORWARD) {
195 			/* must clear the actions because this unlock
196 			 * is about to be retried.  cannot free or do
197 			 * any list manipulation. */
198 			mlog(0, "%s:%.*s: clearing actions, %s\n",
199 			     dlm->name, res->lockname.len,
200 			     res->lockname.name,
201 			     status==DLM_RECOVERING?"recovering":
202 			     (status==DLM_MIGRATING?"migrating":
203 			      "forward"));
204 			actions = 0;
205 		}
206 		if (flags & LKM_CANCEL)
207 			lock->cancel_pending = 0;
208 		else
209 			lock->unlock_pending = 0;
210 
211 	}
212 
213 	/* get an extra ref on lock.  if we are just switching
214 	 * lists here, we dont want the lock to go away. */
215 	dlm_lock_get(lock);
216 
217 	if (actions & DLM_UNLOCK_REMOVE_LOCK) {
218 		list_del_init(&lock->list);
219 		dlm_lock_put(lock);
220 	}
221 	if (actions & DLM_UNLOCK_REGRANT_LOCK) {
222 		dlm_lock_get(lock);
223 		list_add_tail(&lock->list, &res->granted);
224 	}
225 	if (actions & DLM_UNLOCK_CLEAR_CONVERT_TYPE) {
226 		mlog(0, "clearing convert_type at %smaster node\n",
227 		     master_node ? "" : "non-");
228 		lock->ml.convert_type = LKM_IVMODE;
229 	}
230 
231 	/* remove the extra ref on lock */
232 	dlm_lock_put(lock);
233 
234 leave:
235 	res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
236 	if (!dlm_lock_on_list(&res->converting, lock))
237 		BUG_ON(lock->ml.convert_type != LKM_IVMODE);
238 	else
239 		BUG_ON(lock->ml.convert_type == LKM_IVMODE);
240 	spin_unlock(&lock->spinlock);
241 	spin_unlock(&res->spinlock);
242 	wake_up(&res->wq);
243 
244 	/* let the caller's final dlm_lock_put handle the actual kfree */
245 	if (actions & DLM_UNLOCK_FREE_LOCK) {
246 		/* this should always be coupled with list removal */
247 		BUG_ON(!(actions & DLM_UNLOCK_REMOVE_LOCK));
248 		mlog(0, "lock %u:%llu should be gone now! refs=%d\n",
249 		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
250 		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
251 		     atomic_read(&lock->lock_refs.refcount)-1);
252 		dlm_lock_put(lock);
253 	}
254 	if (actions & DLM_UNLOCK_CALL_AST)
255 		*call_ast = 1;
256 
257 	/* if cancel or unlock succeeded, lvb work is done */
258 	if (status == DLM_NORMAL)
259 		lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);
260 
261 	return status;
262 }
263 
264 void dlm_commit_pending_unlock(struct dlm_lock_resource *res,
265 			       struct dlm_lock *lock)
266 {
267 	/* leave DLM_LKSB_PUT_LVB on the lksb so any final
268 	 * update of the lvb will be sent to the new master */
269 	list_del_init(&lock->list);
270 }
271 
272 void dlm_commit_pending_cancel(struct dlm_lock_resource *res,
273 			       struct dlm_lock *lock)
274 {
275 	list_move_tail(&lock->list, &res->granted);
276 	lock->ml.convert_type = LKM_IVMODE;
277 }
278 
279 
280 static inline enum dlm_status dlmunlock_master(struct dlm_ctxt *dlm,
281 					  struct dlm_lock_resource *res,
282 					  struct dlm_lock *lock,
283 					  struct dlm_lockstatus *lksb,
284 					  int flags,
285 					  int *call_ast)
286 {
287 	return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 1);
288 }
289 
290 static inline enum dlm_status dlmunlock_remote(struct dlm_ctxt *dlm,
291 					  struct dlm_lock_resource *res,
292 					  struct dlm_lock *lock,
293 					  struct dlm_lockstatus *lksb,
294 					  int flags, int *call_ast)
295 {
296 	return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 0);
297 }
298 
299 /*
300  * locking:
301  *   caller needs:  none
302  *   taken:         none
303  *   held on exit:  none
304  * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
305  */
306 static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
307 						 struct dlm_lock_resource *res,
308 						 struct dlm_lock *lock,
309 						 struct dlm_lockstatus *lksb,
310 						 int flags,
311 						 u8 owner)
312 {
313 	struct dlm_unlock_lock unlock;
314 	int tmpret;
315 	enum dlm_status ret;
316 	int status = 0;
317 	struct kvec vec[2];
318 	size_t veclen = 1;
319 
320 	mlog(0, "%.*s\n", res->lockname.len, res->lockname.name);
321 
322 	if (owner == dlm->node_num) {
323 		/* ended up trying to contact ourself.  this means
324 		 * that the lockres had been remote but became local
325 		 * via a migration.  just retry it, now as local */
326 		mlog(0, "%s:%.*s: this node became the master due to a "
327 		     "migration, re-evaluate now\n", dlm->name,
328 		     res->lockname.len, res->lockname.name);
329 		return DLM_FORWARD;
330 	}
331 
332 	memset(&unlock, 0, sizeof(unlock));
333 	unlock.node_idx = dlm->node_num;
334 	unlock.flags = cpu_to_be32(flags);
335 	unlock.cookie = lock->ml.cookie;
336 	unlock.namelen = res->lockname.len;
337 	memcpy(unlock.name, res->lockname.name, unlock.namelen);
338 
339 	vec[0].iov_len = sizeof(struct dlm_unlock_lock);
340 	vec[0].iov_base = &unlock;
341 
342 	if (flags & LKM_PUT_LVB) {
343 		/* extra data to send if we are updating lvb */
344 		vec[1].iov_len = DLM_LVB_LEN;
345 		vec[1].iov_base = lock->lksb->lvb;
346 		veclen++;
347 	}
348 
349 	tmpret = o2net_send_message_vec(DLM_UNLOCK_LOCK_MSG, dlm->key,
350 					vec, veclen, owner, &status);
351 	if (tmpret >= 0) {
352 		// successfully sent and received
353 		if (status == DLM_FORWARD)
354 			mlog(0, "master was in-progress.  retry\n");
355 		ret = status;
356 	} else {
357 		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
358 		     "node %u\n", tmpret, DLM_UNLOCK_LOCK_MSG, dlm->key, owner);
359 		if (dlm_is_host_down(tmpret)) {
360 			/* NOTE: this seems strange, but it is what we want.
361 			 * when the master goes down during a cancel or
362 			 * unlock, the recovery code completes the operation
363 			 * as if the master had not died, then passes the
364 			 * updated state to the recovery master.  this thread
365 			 * just needs to finish out the operation and call
366 			 * the unlockast. */
367 			ret = DLM_NORMAL;
368 		} else {
369 			/* something bad.  this will BUG in ocfs2 */
370 			ret = dlm_err_to_dlm_status(tmpret);
371 		}
372 	}
373 
374 	return ret;
375 }
376 
377 /*
378  * locking:
379  *   caller needs:  none
380  *   taken:         takes and drops res->spinlock
381  *   held on exit:  none
382  * returns: DLM_NORMAL, DLM_BADARGS, DLM_IVLOCKID,
383  *          return value from dlmunlock_master
384  */
385 int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
386 			    void **ret_data)
387 {
388 	struct dlm_ctxt *dlm = data;
389 	struct dlm_unlock_lock *unlock = (struct dlm_unlock_lock *)msg->buf;
390 	struct dlm_lock_resource *res = NULL;
391 	struct list_head *iter;
392 	struct dlm_lock *lock = NULL;
393 	enum dlm_status status = DLM_NORMAL;
394 	int found = 0, i;
395 	struct dlm_lockstatus *lksb = NULL;
396 	int ignore;
397 	u32 flags;
398 	struct list_head *queue;
399 
400 	flags = be32_to_cpu(unlock->flags);
401 
402 	if (flags & LKM_GET_LVB) {
403 		mlog(ML_ERROR, "bad args!  GET_LVB specified on unlock!\n");
404 		return DLM_BADARGS;
405 	}
406 
407 	if ((flags & (LKM_PUT_LVB|LKM_CANCEL)) == (LKM_PUT_LVB|LKM_CANCEL)) {
408 		mlog(ML_ERROR, "bad args!  cannot modify lvb on a CANCEL "
409 		     "request!\n");
410 		return DLM_BADARGS;
411 	}
412 
413 	if (unlock->namelen > DLM_LOCKID_NAME_MAX) {
414 		mlog(ML_ERROR, "Invalid name length in unlock handler!\n");
415 		return DLM_IVBUFLEN;
416 	}
417 
418 	if (!dlm_grab(dlm))
419 		return DLM_REJECTED;
420 
421 	mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
422 			"Domain %s not fully joined!\n", dlm->name);
423 
424 	mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" : "none");
425 
426 	res = dlm_lookup_lockres(dlm, unlock->name, unlock->namelen);
427 	if (!res) {
428 		/* We assume here that a no lock resource simply means
429 		 * it was migrated away and destroyed before the other
430 		 * node could detect it. */
431 		mlog(0, "returning DLM_FORWARD -- res no longer exists\n");
432 		status = DLM_FORWARD;
433 		goto not_found;
434 	}
435 
436 	queue=&res->granted;
437 	found = 0;
438 	spin_lock(&res->spinlock);
439 	if (res->state & DLM_LOCK_RES_RECOVERING) {
440 		spin_unlock(&res->spinlock);
441 		mlog(0, "returning DLM_RECOVERING\n");
442 		status = DLM_RECOVERING;
443 		goto leave;
444 	}
445 
446 	if (res->state & DLM_LOCK_RES_MIGRATING) {
447 		spin_unlock(&res->spinlock);
448 		mlog(0, "returning DLM_MIGRATING\n");
449 		status = DLM_MIGRATING;
450 		goto leave;
451 	}
452 
453 	if (res->owner != dlm->node_num) {
454 		spin_unlock(&res->spinlock);
455 		mlog(0, "returning DLM_FORWARD -- not master\n");
456 		status = DLM_FORWARD;
457 		goto leave;
458 	}
459 
460 	for (i=0; i<3; i++) {
461 		list_for_each(iter, queue) {
462 			lock = list_entry(iter, struct dlm_lock, list);
463 			if (lock->ml.cookie == unlock->cookie &&
464 		    	    lock->ml.node == unlock->node_idx) {
465 				dlm_lock_get(lock);
466 				found = 1;
467 				break;
468 			}
469 		}
470 		if (found)
471 			break;
472 		/* scan granted -> converting -> blocked queues */
473 		queue++;
474 	}
475 	spin_unlock(&res->spinlock);
476 	if (!found) {
477 		status = DLM_IVLOCKID;
478 		goto not_found;
479 	}
480 
481 	/* lock was found on queue */
482 	lksb = lock->lksb;
483 	if (flags & (LKM_VALBLK|LKM_PUT_LVB) &&
484 	    lock->ml.type != LKM_EXMODE)
485 		flags &= ~(LKM_VALBLK|LKM_PUT_LVB);
486 
487 	/* unlockast only called on originating node */
488 	if (flags & LKM_PUT_LVB) {
489 		lksb->flags |= DLM_LKSB_PUT_LVB;
490 		memcpy(&lksb->lvb[0], &unlock->lvb[0], DLM_LVB_LEN);
491 	}
492 
493 	/* if this is in-progress, propagate the DLM_FORWARD
494 	 * all the way back out */
495 	status = dlmunlock_master(dlm, res, lock, lksb, flags, &ignore);
496 	if (status == DLM_FORWARD)
497 		mlog(0, "lockres is in progress\n");
498 
499 	if (flags & LKM_PUT_LVB)
500 		lksb->flags &= ~DLM_LKSB_PUT_LVB;
501 
502 	dlm_lockres_calc_usage(dlm, res);
503 	dlm_kick_thread(dlm, res);
504 
505 not_found:
506 	if (!found)
507 		mlog(ML_ERROR, "failed to find lock to unlock! "
508 			       "cookie=%u:%llu\n",
509 		     dlm_get_lock_cookie_node(be64_to_cpu(unlock->cookie)),
510 		     dlm_get_lock_cookie_seq(be64_to_cpu(unlock->cookie)));
511 	else
512 		dlm_lock_put(lock);
513 
514 leave:
515 	if (res)
516 		dlm_lockres_put(res);
517 
518 	dlm_put(dlm);
519 
520 	return status;
521 }
522 
523 
524 static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
525 					      struct dlm_lock_resource *res,
526 					      struct dlm_lock *lock,
527 					      struct dlm_lockstatus *lksb,
528 					      int *actions)
529 {
530 	enum dlm_status status;
531 
532 	if (dlm_lock_on_list(&res->blocked, lock)) {
533 		/* cancel this outright */
534 		status = DLM_NORMAL;
535 		*actions = (DLM_UNLOCK_CALL_AST |
536 			    DLM_UNLOCK_REMOVE_LOCK);
537 	} else if (dlm_lock_on_list(&res->converting, lock)) {
538 		/* cancel the request, put back on granted */
539 		status = DLM_NORMAL;
540 		*actions = (DLM_UNLOCK_CALL_AST |
541 			    DLM_UNLOCK_REMOVE_LOCK |
542 			    DLM_UNLOCK_REGRANT_LOCK |
543 			    DLM_UNLOCK_CLEAR_CONVERT_TYPE);
544 	} else if (dlm_lock_on_list(&res->granted, lock)) {
545 		/* too late, already granted. */
546 		status = DLM_CANCELGRANT;
547 		*actions = DLM_UNLOCK_CALL_AST;
548 	} else {
549 		mlog(ML_ERROR, "lock to cancel is not on any list!\n");
550 		status = DLM_IVLOCKID;
551 		*actions = 0;
552 	}
553 	return status;
554 }
555 
556 static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
557 					      struct dlm_lock_resource *res,
558 					      struct dlm_lock *lock,
559 					      struct dlm_lockstatus *lksb,
560 					      int *actions)
561 {
562 	enum dlm_status status;
563 
564 	/* unlock request */
565 	if (!dlm_lock_on_list(&res->granted, lock)) {
566 		status = DLM_DENIED;
567 		dlm_error(status);
568 		*actions = 0;
569 	} else {
570 		/* unlock granted lock */
571 		status = DLM_NORMAL;
572 		*actions = (DLM_UNLOCK_FREE_LOCK |
573 			    DLM_UNLOCK_CALL_AST |
574 			    DLM_UNLOCK_REMOVE_LOCK);
575 	}
576 	return status;
577 }
578 
579 /* there seems to be no point in doing this async
580  * since (even for the remote case) there is really
581  * no work to queue up... so just do it and fire the
582  * unlockast by hand when done... */
583 enum dlm_status dlmunlock(struct dlm_ctxt *dlm, struct dlm_lockstatus *lksb,
584 			  int flags, dlm_astunlockfunc_t *unlockast, void *data)
585 {
586 	enum dlm_status status;
587 	struct dlm_lock_resource *res;
588 	struct dlm_lock *lock = NULL;
589 	int call_ast, is_master;
590 
591 	if (!lksb) {
592 		dlm_error(DLM_BADARGS);
593 		return DLM_BADARGS;
594 	}
595 
596 	if (flags & ~(LKM_CANCEL | LKM_VALBLK | LKM_INVVALBLK)) {
597 		dlm_error(DLM_BADPARAM);
598 		return DLM_BADPARAM;
599 	}
600 
601 	if ((flags & (LKM_VALBLK | LKM_CANCEL)) == (LKM_VALBLK | LKM_CANCEL)) {
602 		mlog(0, "VALBLK given with CANCEL: ignoring VALBLK\n");
603 		flags &= ~LKM_VALBLK;
604 	}
605 
606 	if (!lksb->lockid || !lksb->lockid->lockres) {
607 		dlm_error(DLM_BADPARAM);
608 		return DLM_BADPARAM;
609 	}
610 
611 	lock = lksb->lockid;
612 	BUG_ON(!lock);
613 	dlm_lock_get(lock);
614 
615 	res = lock->lockres;
616 	BUG_ON(!res);
617 	dlm_lockres_get(res);
618 retry:
619 	call_ast = 0;
620 	/* need to retry up here because owner may have changed */
621 	mlog(0, "lock=%p res=%p\n", lock, res);
622 
623 	spin_lock(&res->spinlock);
624 	is_master = (res->owner == dlm->node_num);
625 	if (flags & LKM_VALBLK && lock->ml.type != LKM_EXMODE)
626 		flags &= ~LKM_VALBLK;
627 	spin_unlock(&res->spinlock);
628 
629 	if (is_master) {
630 		status = dlmunlock_master(dlm, res, lock, lksb, flags,
631 					  &call_ast);
632 		mlog(0, "done calling dlmunlock_master: returned %d, "
633 		     "call_ast is %d\n", status, call_ast);
634 	} else {
635 		status = dlmunlock_remote(dlm, res, lock, lksb, flags,
636 					  &call_ast);
637 		mlog(0, "done calling dlmunlock_remote: returned %d, "
638 		     "call_ast is %d\n", status, call_ast);
639 	}
640 
641 	if (status == DLM_RECOVERING ||
642 	    status == DLM_MIGRATING ||
643 	    status == DLM_FORWARD) {
644 		/* We want to go away for a tiny bit to allow recovery
645 		 * / migration to complete on this resource. I don't
646 		 * know of any wait queue we could sleep on as this
647 		 * may be happening on another node. Perhaps the
648 		 * proper solution is to queue up requests on the
649 		 * other end? */
650 
651 		/* do we want to yield(); ?? */
652 		msleep(50);
653 
654 		mlog(0, "retrying unlock due to pending recovery/"
655 		     "migration/in-progress\n");
656 		goto retry;
657 	}
658 
659 	if (call_ast) {
660 		mlog(0, "calling unlockast(%p, %d)\n", data, status);
661 		if (is_master) {
662 			/* it is possible that there is one last bast
663 			 * pending.  make sure it is flushed, then
664 			 * call the unlockast.
665 			 * not an issue if this is a mastered remotely,
666 			 * since this lock has been removed from the
667 			 * lockres queues and cannot be found. */
668 			dlm_kick_thread(dlm, NULL);
669 			wait_event(dlm->ast_wq,
670 				   dlm_lock_basts_flushed(dlm, lock));
671 		}
672 		(*unlockast)(data, status);
673 	}
674 
675 	if (status == DLM_CANCELGRANT)
676 		status = DLM_NORMAL;
677 
678 	if (status == DLM_NORMAL) {
679 		mlog(0, "kicking the thread\n");
680 		dlm_kick_thread(dlm, res);
681 	} else
682 		dlm_error(status);
683 
684 	dlm_lockres_calc_usage(dlm, res);
685 	dlm_lockres_put(res);
686 	dlm_lock_put(lock);
687 
688 	mlog(0, "returning status=%d!\n", status);
689 	return status;
690 }
691 EXPORT_SYMBOL_GPL(dlmunlock);
692 
693