Merge ../ntfs-2.6-devel
[linux-2.6] / 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         } else if (dlm_is_recovery_lock(res->lockname.name, 
224                                         res->lockname.len)) {
225                 /* special case for the $RECOVERY lock.
226                  * there will never be an AST delivered to put
227                  * this lock on the proper secondary queue
228                  * (granted), so do it manually. */
229                 mlog(0, "%s: $RECOVERY lock for this node (%u) is "
230                      "mastered by %u; got lock, manually granting (no ast)\n",
231                      dlm->name, dlm->node_num, res->owner);
232                 list_del_init(&lock->list);
233                 list_add_tail(&lock->list, &res->granted);
234         }
235         spin_unlock(&res->spinlock);
236
237         dlm_lockres_calc_usage(dlm, res);
238
239         wake_up(&res->wq);
240         return status;
241 }
242
243
244 /* for remote lock creation.
245  * locking:
246  *   caller needs:  none, but need res->state & DLM_LOCK_RES_IN_PROGRESS
247  *   taken:         none
248  *   held on exit:  none
249  * returns: DLM_NOLOCKMGR, or net status
250  */
251 static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
252                                                struct dlm_lock_resource *res,
253                                                struct dlm_lock *lock, int flags)
254 {
255         struct dlm_create_lock create;
256         int tmpret, status = 0;
257         enum dlm_status ret;
258
259         mlog_entry_void();
260
261         memset(&create, 0, sizeof(create));
262         create.node_idx = dlm->node_num;
263         create.requested_type = lock->ml.type;
264         create.cookie = lock->ml.cookie;
265         create.namelen = res->lockname.len;
266         create.flags = cpu_to_be32(flags);
267         memcpy(create.name, res->lockname.name, create.namelen);
268
269         tmpret = o2net_send_message(DLM_CREATE_LOCK_MSG, dlm->key, &create,
270                                     sizeof(create), res->owner, &status);
271         if (tmpret >= 0) {
272                 // successfully sent and received
273                 ret = status;  // this is already a dlm_status
274         } else {
275                 mlog_errno(tmpret);
276                 if (dlm_is_host_down(tmpret)) {
277                         ret = DLM_RECOVERING;
278                         mlog(0, "node %u died so returning DLM_RECOVERING "
279                              "from lock message!\n", res->owner);
280                 } else {
281                         ret = dlm_err_to_dlm_status(tmpret);
282                 }
283         }
284
285         return ret;
286 }
287
288 void dlm_lock_get(struct dlm_lock *lock)
289 {
290         kref_get(&lock->lock_refs);
291 }
292
293 void dlm_lock_put(struct dlm_lock *lock)
294 {
295         kref_put(&lock->lock_refs, dlm_lock_release);
296 }
297
298 static void dlm_lock_release(struct kref *kref)
299 {
300         struct dlm_lock *lock;
301
302         lock = container_of(kref, struct dlm_lock, lock_refs);
303
304         BUG_ON(!list_empty(&lock->list));
305         BUG_ON(!list_empty(&lock->ast_list));
306         BUG_ON(!list_empty(&lock->bast_list));
307         BUG_ON(lock->ast_pending);
308         BUG_ON(lock->bast_pending);
309
310         dlm_lock_detach_lockres(lock);
311
312         if (lock->lksb_kernel_allocated) {
313                 mlog(0, "freeing kernel-allocated lksb\n");
314                 kfree(lock->lksb);
315         }
316         kfree(lock);
317 }
318
319 /* associate a lock with it's lockres, getting a ref on the lockres */
320 void dlm_lock_attach_lockres(struct dlm_lock *lock,
321                              struct dlm_lock_resource *res)
322 {
323         dlm_lockres_get(res);
324         lock->lockres = res;
325 }
326
327 /* drop ref on lockres, if there is still one associated with lock */
328 static void dlm_lock_detach_lockres(struct dlm_lock *lock)
329 {
330         struct dlm_lock_resource *res;
331
332         res = lock->lockres;
333         if (res) {
334                 lock->lockres = NULL;
335                 mlog(0, "removing lock's lockres reference\n");
336                 dlm_lockres_put(res);
337         }
338 }
339
340 static void dlm_init_lock(struct dlm_lock *newlock, int type,
341                           u8 node, u64 cookie)
342 {
343         INIT_LIST_HEAD(&newlock->list);
344         INIT_LIST_HEAD(&newlock->ast_list);
345         INIT_LIST_HEAD(&newlock->bast_list);
346         spin_lock_init(&newlock->spinlock);
347         newlock->ml.type = type;
348         newlock->ml.convert_type = LKM_IVMODE;
349         newlock->ml.highest_blocked = LKM_IVMODE;
350         newlock->ml.node = node;
351         newlock->ml.pad1 = 0;
352         newlock->ml.list = 0;
353         newlock->ml.flags = 0;
354         newlock->ast = NULL;
355         newlock->bast = NULL;
356         newlock->astdata = NULL;
357         newlock->ml.cookie = cpu_to_be64(cookie);
358         newlock->ast_pending = 0;
359         newlock->bast_pending = 0;
360         newlock->convert_pending = 0;
361         newlock->lock_pending = 0;
362         newlock->unlock_pending = 0;
363         newlock->cancel_pending = 0;
364         newlock->lksb_kernel_allocated = 0;
365
366         kref_init(&newlock->lock_refs);
367 }
368
369 struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
370                                struct dlm_lockstatus *lksb)
371 {
372         struct dlm_lock *lock;
373         int kernel_allocated = 0;
374
375         lock = kcalloc(1, sizeof(*lock), GFP_KERNEL);
376         if (!lock)
377                 return NULL;
378
379         if (!lksb) {
380                 /* zero memory only if kernel-allocated */
381                 lksb = kcalloc(1, sizeof(*lksb), GFP_KERNEL);
382                 if (!lksb) {
383                         kfree(lock);
384                         return NULL;
385                 }
386                 kernel_allocated = 1;
387         }
388
389         dlm_init_lock(lock, type, node, cookie);
390         if (kernel_allocated)
391                 lock->lksb_kernel_allocated = 1;
392         lock->lksb = lksb;
393         lksb->lockid = lock;
394         return lock;
395 }
396
397 /* handler for lock creation net message
398  * locking:
399  *   caller needs:  none
400  *   taken:         takes and drops res->spinlock
401  *   held on exit:  none
402  * returns: DLM_NORMAL, DLM_SYSERR, DLM_IVLOCKID, DLM_NOTQUEUED
403  */
404 int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data)
405 {
406         struct dlm_ctxt *dlm = data;
407         struct dlm_create_lock *create = (struct dlm_create_lock *)msg->buf;
408         struct dlm_lock_resource *res = NULL;
409         struct dlm_lock *newlock = NULL;
410         struct dlm_lockstatus *lksb = NULL;
411         enum dlm_status status = DLM_NORMAL;
412         char *name;
413         unsigned int namelen;
414
415         BUG_ON(!dlm);
416
417         mlog_entry_void();
418
419         if (!dlm_grab(dlm))
420                 return DLM_REJECTED;
421
422         mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
423                         "Domain %s not fully joined!\n", dlm->name);
424
425         name = create->name;
426         namelen = create->namelen;
427
428         status = DLM_IVBUFLEN;
429         if (namelen > DLM_LOCKID_NAME_MAX) {
430                 dlm_error(status);
431                 goto leave;
432         }
433
434         status = DLM_SYSERR;
435         newlock = dlm_new_lock(create->requested_type,
436                                create->node_idx,
437                                be64_to_cpu(create->cookie), NULL);
438         if (!newlock) {
439                 dlm_error(status);
440                 goto leave;
441         }
442
443         lksb = newlock->lksb;
444
445         if (be32_to_cpu(create->flags) & LKM_GET_LVB) {
446                 lksb->flags |= DLM_LKSB_GET_LVB;
447                 mlog(0, "set DLM_LKSB_GET_LVB flag\n");
448         }
449
450         status = DLM_IVLOCKID;
451         res = dlm_lookup_lockres(dlm, name, namelen);
452         if (!res) {
453                 dlm_error(status);
454                 goto leave;
455         }
456
457         spin_lock(&res->spinlock);
458         status = __dlm_lockres_state_to_status(res);
459         spin_unlock(&res->spinlock);
460
461         if (status != DLM_NORMAL) {
462                 mlog(0, "lockres recovering/migrating/in-progress\n");
463                 goto leave;
464         }
465
466         dlm_lock_attach_lockres(newlock, res);
467
468         status = dlmlock_master(dlm, res, newlock, be32_to_cpu(create->flags));
469 leave:
470         if (status != DLM_NORMAL)
471                 if (newlock)
472                         dlm_lock_put(newlock);
473
474         if (res)
475                 dlm_lockres_put(res);
476
477         dlm_put(dlm);
478
479         return status;
480 }
481
482
483 /* fetch next node-local (u8 nodenum + u56 cookie) into u64 */
484 static inline void dlm_get_next_cookie(u8 node_num, u64 *cookie)
485 {
486         u64 tmpnode = node_num;
487
488         /* shift single byte of node num into top 8 bits */
489         tmpnode <<= 56;
490
491         spin_lock(&dlm_cookie_lock);
492         *cookie = (dlm_next_cookie | tmpnode);
493         if (++dlm_next_cookie & 0xff00000000000000ull) {
494                 mlog(0, "This node's cookie will now wrap!\n");
495                 dlm_next_cookie = 1;
496         }
497         spin_unlock(&dlm_cookie_lock);
498 }
499
500 enum dlm_status dlmlock(struct dlm_ctxt *dlm, int mode,
501                         struct dlm_lockstatus *lksb, int flags,
502                         const char *name, dlm_astlockfunc_t *ast, void *data,
503                         dlm_bastlockfunc_t *bast)
504 {
505         enum dlm_status status;
506         struct dlm_lock_resource *res = NULL;
507         struct dlm_lock *lock = NULL;
508         int convert = 0, recovery = 0;
509
510         /* yes this function is a mess.
511          * TODO: clean this up.  lots of common code in the
512          *       lock and convert paths, especially in the retry blocks */
513         if (!lksb) {
514                 dlm_error(DLM_BADARGS);
515                 return DLM_BADARGS;
516         }
517
518         status = DLM_BADPARAM;
519         if (mode != LKM_EXMODE && mode != LKM_PRMODE && mode != LKM_NLMODE) {
520                 dlm_error(status);
521                 goto error;
522         }
523
524         if (flags & ~LKM_VALID_FLAGS) {
525                 dlm_error(status);
526                 goto error;
527         }
528
529         convert = (flags & LKM_CONVERT);
530         recovery = (flags & LKM_RECOVERY);
531
532         if (recovery &&
533             (!dlm_is_recovery_lock(name, strlen(name)) || convert) ) {
534                 dlm_error(status);
535                 goto error;
536         }
537         if (convert && (flags & LKM_LOCAL)) {
538                 mlog(ML_ERROR, "strange LOCAL convert request!\n");
539                 goto error;
540         }
541
542         if (convert) {
543                 /* CONVERT request */
544
545                 /* if converting, must pass in a valid dlm_lock */
546                 lock = lksb->lockid;
547                 if (!lock) {
548                         mlog(ML_ERROR, "NULL lock pointer in convert "
549                              "request\n");
550                         goto error;
551                 }
552
553                 res = lock->lockres;
554                 if (!res) {
555                         mlog(ML_ERROR, "NULL lockres pointer in convert "
556                              "request\n");
557                         goto error;
558                 }
559                 dlm_lockres_get(res);
560
561                 /* XXX: for ocfs2 purposes, the ast/bast/astdata/lksb are
562                  * static after the original lock call.  convert requests will
563                  * ensure that everything is the same, or return DLM_BADARGS.
564                  * this means that DLM_DENIED_NOASTS will never be returned.
565                  */
566                 if (lock->lksb != lksb || lock->ast != ast ||
567                     lock->bast != bast || lock->astdata != data) {
568                         status = DLM_BADARGS;
569                         mlog(ML_ERROR, "new args:  lksb=%p, ast=%p, bast=%p, "
570                              "astdata=%p\n", lksb, ast, bast, data);
571                         mlog(ML_ERROR, "orig args: lksb=%p, ast=%p, bast=%p, "
572                              "astdata=%p\n", lock->lksb, lock->ast,
573                              lock->bast, lock->astdata);
574                         goto error;
575                 }
576 retry_convert:
577                 dlm_wait_for_recovery(dlm);
578
579                 if (res->owner == dlm->node_num)
580                         status = dlmconvert_master(dlm, res, lock, flags, mode);
581                 else
582                         status = dlmconvert_remote(dlm, res, lock, flags, mode);
583                 if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
584                     status == DLM_FORWARD) {
585                         /* for now, see how this works without sleeping
586                          * and just retry right away.  I suspect the reco
587                          * or migration will complete fast enough that
588                          * no waiting will be necessary */
589                         mlog(0, "retrying convert with migration/recovery/"
590                              "in-progress\n");
591                         msleep(100);
592                         goto retry_convert;
593                 }
594         } else {
595                 u64 tmpcookie;
596
597                 /* LOCK request */
598                 status = DLM_BADARGS;
599                 if (!name) {
600                         dlm_error(status);
601                         goto error;
602                 }
603
604                 status = DLM_IVBUFLEN;
605                 if (strlen(name) > DLM_LOCKID_NAME_MAX || strlen(name) < 1) {
606                         dlm_error(status);
607                         goto error;
608                 }
609
610                 dlm_get_next_cookie(dlm->node_num, &tmpcookie);
611                 lock = dlm_new_lock(mode, dlm->node_num, tmpcookie, lksb);
612                 if (!lock) {
613                         dlm_error(status);
614                         goto error;
615                 }
616
617                 if (!recovery)
618                         dlm_wait_for_recovery(dlm);
619
620                 /* find or create the lock resource */
621                 res = dlm_get_lock_resource(dlm, name, flags);
622                 if (!res) {
623                         status = DLM_IVLOCKID;
624                         dlm_error(status);
625                         goto error;
626                 }
627
628                 mlog(0, "type=%d, flags = 0x%x\n", mode, flags);
629                 mlog(0, "creating lock: lock=%p res=%p\n", lock, res);
630
631                 dlm_lock_attach_lockres(lock, res);
632                 lock->ast = ast;
633                 lock->bast = bast;
634                 lock->astdata = data;
635
636 retry_lock:
637                 if (flags & LKM_VALBLK) {
638                         mlog(0, "LKM_VALBLK passed by caller\n");
639
640                         /* LVB requests for non PR, PW or EX locks are
641                          * ignored. */
642                         if (mode < LKM_PRMODE)
643                                 flags &= ~LKM_VALBLK;
644                         else {
645                                 flags |= LKM_GET_LVB;
646                                 lock->lksb->flags |= DLM_LKSB_GET_LVB;
647                         }
648                 }
649
650                 if (res->owner == dlm->node_num)
651                         status = dlmlock_master(dlm, res, lock, flags);
652                 else
653                         status = dlmlock_remote(dlm, res, lock, flags);
654
655                 if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
656                     status == DLM_FORWARD) {
657                         mlog(0, "retrying lock with migration/"
658                              "recovery/in progress\n");
659                         msleep(100);
660                         /* no waiting for dlm_reco_thread */
661                         if (recovery) {
662                                 if (status == DLM_RECOVERING) {
663                                         mlog(0, "%s: got RECOVERING "
664                                              "for $REOCVERY lock, master "
665                                              "was %u\n", dlm->name, 
666                                              res->owner);
667                                         dlm_wait_for_node_death(dlm, res->owner, 
668                                                         DLM_NODE_DEATH_WAIT_MAX);
669                                 }
670                         } else {
671                                 dlm_wait_for_recovery(dlm);
672                         }
673                         goto retry_lock;
674                 }
675
676                 if (status != DLM_NORMAL) {
677                         lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
678                         if (status != DLM_NOTQUEUED)
679                                 dlm_error(status);
680                         goto error;
681                 }
682         }
683
684 error:
685         if (status != DLM_NORMAL) {
686                 if (lock && !convert)
687                         dlm_lock_put(lock);
688                 // this is kind of unnecessary
689                 lksb->status = status;
690         }
691
692         /* put lockres ref from the convert path
693          * or from dlm_get_lock_resource */
694         if (res)
695                 dlm_lockres_put(res);
696
697         return status;
698 }
699 EXPORT_SYMBOL_GPL(dlmlock);