[PATCH] fs: use list_move()
[linux-2.6.git] / 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                 } else {
145                         mlog(0, "%s: returning DLM_NORMAL to "
146                              "node %u for reco lock\n", dlm->name,
147                              lock->ml.node);
148                 }
149         } else {
150                 /* for NOQUEUE request, unless we get the
151                  * lock right away, return DLM_NOTQUEUED */
152                 if (flags & LKM_NOQUEUE) {
153                         status = DLM_NOTQUEUED;
154                         if (dlm_is_recovery_lock(res->lockname.name,
155                                                  res->lockname.len)) {
156                                 mlog(0, "%s: returning NOTQUEUED to "
157                                      "node %u for reco lock\n", dlm->name,
158                                      lock->ml.node);
159                         }
160                 } else {
161                         dlm_lock_get(lock);
162                         list_add_tail(&lock->list, &res->blocked);
163                         kick_thread = 1;
164                 }
165         }
166
167         spin_unlock(&res->spinlock);
168         wake_up(&res->wq);
169
170         /* either queue the ast or release it */
171         if (call_ast)
172                 dlm_queue_ast(dlm, lock);
173         else
174                 dlm_lockres_release_ast(dlm, res);
175
176         dlm_lockres_calc_usage(dlm, res);
177         if (kick_thread)
178                 dlm_kick_thread(dlm, res);
179
180         return status;
181 }
182
183 void dlm_revert_pending_lock(struct dlm_lock_resource *res,
184                              struct dlm_lock *lock)
185 {
186         /* remove from local queue if it failed */
187         list_del_init(&lock->list);
188         lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
189 }
190
191
192 /*
193  * locking:
194  *   caller needs:  none
195  *   taken:         takes and drops res->spinlock
196  *   held on exit:  none
197  * returns: DLM_DENIED, DLM_RECOVERING, or net status
198  */
199 static enum dlm_status dlmlock_remote(struct dlm_ctxt *dlm,
200                                       struct dlm_lock_resource *res,
201                                       struct dlm_lock *lock, int flags)
202 {
203         enum dlm_status status = DLM_DENIED;
204
205         mlog_entry("type=%d\n", lock->ml.type);
206         mlog(0, "lockres %.*s, flags = 0x%x\n", res->lockname.len,
207              res->lockname.name, flags);
208
209         spin_lock(&res->spinlock);
210
211         /* will exit this call with spinlock held */
212         __dlm_wait_on_lockres(res);
213         res->state |= DLM_LOCK_RES_IN_PROGRESS;
214
215         /* add lock to local (secondary) queue */
216         dlm_lock_get(lock);
217         list_add_tail(&lock->list, &res->blocked);
218         lock->lock_pending = 1;
219         spin_unlock(&res->spinlock);
220
221         /* spec seems to say that you will get DLM_NORMAL when the lock
222          * has been queued, meaning we need to wait for a reply here. */
223         status = dlm_send_remote_lock_request(dlm, res, lock, flags);
224
225         spin_lock(&res->spinlock);
226         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
227         lock->lock_pending = 0;
228         if (status != DLM_NORMAL) {
229                 if (status != DLM_NOTQUEUED)
230                         dlm_error(status);
231                 dlm_revert_pending_lock(res, lock);
232                 dlm_lock_put(lock);
233         } else if (dlm_is_recovery_lock(res->lockname.name, 
234                                         res->lockname.len)) {
235                 /* special case for the $RECOVERY lock.
236                  * there will never be an AST delivered to put
237                  * this lock on the proper secondary queue
238                  * (granted), so do it manually. */
239                 mlog(0, "%s: $RECOVERY lock for this node (%u) is "
240                      "mastered by %u; got lock, manually granting (no ast)\n",
241                      dlm->name, dlm->node_num, res->owner);
242                 list_move_tail(&lock->list, &res->granted);
243         }
244         spin_unlock(&res->spinlock);
245
246         dlm_lockres_calc_usage(dlm, res);
247
248         wake_up(&res->wq);
249         return status;
250 }
251
252
253 /* for remote lock creation.
254  * locking:
255  *   caller needs:  none, but need res->state & DLM_LOCK_RES_IN_PROGRESS
256  *   taken:         none
257  *   held on exit:  none
258  * returns: DLM_NOLOCKMGR, or net status
259  */
260 static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
261                                                struct dlm_lock_resource *res,
262                                                struct dlm_lock *lock, int flags)
263 {
264         struct dlm_create_lock create;
265         int tmpret, status = 0;
266         enum dlm_status ret;
267
268         mlog_entry_void();
269
270         memset(&create, 0, sizeof(create));
271         create.node_idx = dlm->node_num;
272         create.requested_type = lock->ml.type;
273         create.cookie = lock->ml.cookie;
274         create.namelen = res->lockname.len;
275         create.flags = cpu_to_be32(flags);
276         memcpy(create.name, res->lockname.name, create.namelen);
277
278         tmpret = o2net_send_message(DLM_CREATE_LOCK_MSG, dlm->key, &create,
279                                     sizeof(create), res->owner, &status);
280         if (tmpret >= 0) {
281                 // successfully sent and received
282                 ret = status;  // this is already a dlm_status
283         } else {
284                 mlog_errno(tmpret);
285                 if (dlm_is_host_down(tmpret)) {
286                         ret = DLM_RECOVERING;
287                         mlog(0, "node %u died so returning DLM_RECOVERING "
288                              "from lock message!\n", res->owner);
289                 } else {
290                         ret = dlm_err_to_dlm_status(tmpret);
291                 }
292         }
293
294         return ret;
295 }
296
297 void dlm_lock_get(struct dlm_lock *lock)
298 {
299         kref_get(&lock->lock_refs);
300 }
301
302 void dlm_lock_put(struct dlm_lock *lock)
303 {
304         kref_put(&lock->lock_refs, dlm_lock_release);
305 }
306
307 static void dlm_lock_release(struct kref *kref)
308 {
309         struct dlm_lock *lock;
310
311         lock = container_of(kref, struct dlm_lock, lock_refs);
312
313         BUG_ON(!list_empty(&lock->list));
314         BUG_ON(!list_empty(&lock->ast_list));
315         BUG_ON(!list_empty(&lock->bast_list));
316         BUG_ON(lock->ast_pending);
317         BUG_ON(lock->bast_pending);
318
319         dlm_lock_detach_lockres(lock);
320
321         if (lock->lksb_kernel_allocated) {
322                 mlog(0, "freeing kernel-allocated lksb\n");
323                 kfree(lock->lksb);
324         }
325         kfree(lock);
326 }
327
328 /* associate a lock with it's lockres, getting a ref on the lockres */
329 void dlm_lock_attach_lockres(struct dlm_lock *lock,
330                              struct dlm_lock_resource *res)
331 {
332         dlm_lockres_get(res);
333         lock->lockres = res;
334 }
335
336 /* drop ref on lockres, if there is still one associated with lock */
337 static void dlm_lock_detach_lockres(struct dlm_lock *lock)
338 {
339         struct dlm_lock_resource *res;
340
341         res = lock->lockres;
342         if (res) {
343                 lock->lockres = NULL;
344                 mlog(0, "removing lock's lockres reference\n");
345                 dlm_lockres_put(res);
346         }
347 }
348
349 static void dlm_init_lock(struct dlm_lock *newlock, int type,
350                           u8 node, u64 cookie)
351 {
352         INIT_LIST_HEAD(&newlock->list);
353         INIT_LIST_HEAD(&newlock->ast_list);
354         INIT_LIST_HEAD(&newlock->bast_list);
355         spin_lock_init(&newlock->spinlock);
356         newlock->ml.type = type;
357         newlock->ml.convert_type = LKM_IVMODE;
358         newlock->ml.highest_blocked = LKM_IVMODE;
359         newlock->ml.node = node;
360         newlock->ml.pad1 = 0;
361         newlock->ml.list = 0;
362         newlock->ml.flags = 0;
363         newlock->ast = NULL;
364         newlock->bast = NULL;
365         newlock->astdata = NULL;
366         newlock->ml.cookie = cpu_to_be64(cookie);
367         newlock->ast_pending = 0;
368         newlock->bast_pending = 0;
369         newlock->convert_pending = 0;
370         newlock->lock_pending = 0;
371         newlock->unlock_pending = 0;
372         newlock->cancel_pending = 0;
373         newlock->lksb_kernel_allocated = 0;
374
375         kref_init(&newlock->lock_refs);
376 }
377
378 struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
379                                struct dlm_lockstatus *lksb)
380 {
381         struct dlm_lock *lock;
382         int kernel_allocated = 0;
383
384         lock = kcalloc(1, sizeof(*lock), GFP_KERNEL);
385         if (!lock)
386                 return NULL;
387
388         if (!lksb) {
389                 /* zero memory only if kernel-allocated */
390                 lksb = kcalloc(1, sizeof(*lksb), GFP_KERNEL);
391                 if (!lksb) {
392                         kfree(lock);
393                         return NULL;
394                 }
395                 kernel_allocated = 1;
396         }
397
398         dlm_init_lock(lock, type, node, cookie);
399         if (kernel_allocated)
400                 lock->lksb_kernel_allocated = 1;
401         lock->lksb = lksb;
402         lksb->lockid = lock;
403         return lock;
404 }
405
406 /* handler for lock creation net message
407  * locking:
408  *   caller needs:  none
409  *   taken:         takes and drops res->spinlock
410  *   held on exit:  none
411  * returns: DLM_NORMAL, DLM_SYSERR, DLM_IVLOCKID, DLM_NOTQUEUED
412  */
413 int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data)
414 {
415         struct dlm_ctxt *dlm = data;
416         struct dlm_create_lock *create = (struct dlm_create_lock *)msg->buf;
417         struct dlm_lock_resource *res = NULL;
418         struct dlm_lock *newlock = NULL;
419         struct dlm_lockstatus *lksb = NULL;
420         enum dlm_status status = DLM_NORMAL;
421         char *name;
422         unsigned int namelen;
423
424         BUG_ON(!dlm);
425
426         mlog_entry_void();
427
428         if (!dlm_grab(dlm))
429                 return DLM_REJECTED;
430
431         mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
432                         "Domain %s not fully joined!\n", dlm->name);
433
434         name = create->name;
435         namelen = create->namelen;
436
437         status = DLM_IVBUFLEN;
438         if (namelen > DLM_LOCKID_NAME_MAX) {
439                 dlm_error(status);
440                 goto leave;
441         }
442
443         status = DLM_SYSERR;
444         newlock = dlm_new_lock(create->requested_type,
445                                create->node_idx,
446                                be64_to_cpu(create->cookie), NULL);
447         if (!newlock) {
448                 dlm_error(status);
449                 goto leave;
450         }
451
452         lksb = newlock->lksb;
453
454         if (be32_to_cpu(create->flags) & LKM_GET_LVB) {
455                 lksb->flags |= DLM_LKSB_GET_LVB;
456                 mlog(0, "set DLM_LKSB_GET_LVB flag\n");
457         }
458
459         status = DLM_IVLOCKID;
460         res = dlm_lookup_lockres(dlm, name, namelen);
461         if (!res) {
462                 dlm_error(status);
463                 goto leave;
464         }
465
466         spin_lock(&res->spinlock);
467         status = __dlm_lockres_state_to_status(res);
468         spin_unlock(&res->spinlock);
469
470         if (status != DLM_NORMAL) {
471                 mlog(0, "lockres recovering/migrating/in-progress\n");
472                 goto leave;
473         }
474
475         dlm_lock_attach_lockres(newlock, res);
476
477         status = dlmlock_master(dlm, res, newlock, be32_to_cpu(create->flags));
478 leave:
479         if (status != DLM_NORMAL)
480                 if (newlock)
481                         dlm_lock_put(newlock);
482
483         if (res)
484                 dlm_lockres_put(res);
485
486         dlm_put(dlm);
487
488         return status;
489 }
490
491
492 /* fetch next node-local (u8 nodenum + u56 cookie) into u64 */
493 static inline void dlm_get_next_cookie(u8 node_num, u64 *cookie)
494 {
495         u64 tmpnode = node_num;
496
497         /* shift single byte of node num into top 8 bits */
498         tmpnode <<= 56;
499
500         spin_lock(&dlm_cookie_lock);
501         *cookie = (dlm_next_cookie | tmpnode);
502         if (++dlm_next_cookie & 0xff00000000000000ull) {
503                 mlog(0, "This node's cookie will now wrap!\n");
504                 dlm_next_cookie = 1;
505         }
506         spin_unlock(&dlm_cookie_lock);
507 }
508
509 enum dlm_status dlmlock(struct dlm_ctxt *dlm, int mode,
510                         struct dlm_lockstatus *lksb, int flags,
511                         const char *name, dlm_astlockfunc_t *ast, void *data,
512                         dlm_bastlockfunc_t *bast)
513 {
514         enum dlm_status status;
515         struct dlm_lock_resource *res = NULL;
516         struct dlm_lock *lock = NULL;
517         int convert = 0, recovery = 0;
518
519         /* yes this function is a mess.
520          * TODO: clean this up.  lots of common code in the
521          *       lock and convert paths, especially in the retry blocks */
522         if (!lksb) {
523                 dlm_error(DLM_BADARGS);
524                 return DLM_BADARGS;
525         }
526
527         status = DLM_BADPARAM;
528         if (mode != LKM_EXMODE && mode != LKM_PRMODE && mode != LKM_NLMODE) {
529                 dlm_error(status);
530                 goto error;
531         }
532
533         if (flags & ~LKM_VALID_FLAGS) {
534                 dlm_error(status);
535                 goto error;
536         }
537
538         convert = (flags & LKM_CONVERT);
539         recovery = (flags & LKM_RECOVERY);
540
541         if (recovery &&
542             (!dlm_is_recovery_lock(name, strlen(name)) || convert) ) {
543                 dlm_error(status);
544                 goto error;
545         }
546         if (convert && (flags & LKM_LOCAL)) {
547                 mlog(ML_ERROR, "strange LOCAL convert request!\n");
548                 goto error;
549         }
550
551         if (convert) {
552                 /* CONVERT request */
553
554                 /* if converting, must pass in a valid dlm_lock */
555                 lock = lksb->lockid;
556                 if (!lock) {
557                         mlog(ML_ERROR, "NULL lock pointer in convert "
558                              "request\n");
559                         goto error;
560                 }
561
562                 res = lock->lockres;
563                 if (!res) {
564                         mlog(ML_ERROR, "NULL lockres pointer in convert "
565                              "request\n");
566                         goto error;
567                 }
568                 dlm_lockres_get(res);
569
570                 /* XXX: for ocfs2 purposes, the ast/bast/astdata/lksb are
571                  * static after the original lock call.  convert requests will
572                  * ensure that everything is the same, or return DLM_BADARGS.
573                  * this means that DLM_DENIED_NOASTS will never be returned.
574                  */
575                 if (lock->lksb != lksb || lock->ast != ast ||
576                     lock->bast != bast || lock->astdata != data) {
577                         status = DLM_BADARGS;
578                         mlog(ML_ERROR, "new args:  lksb=%p, ast=%p, bast=%p, "
579                              "astdata=%p\n", lksb, ast, bast, data);
580                         mlog(ML_ERROR, "orig args: lksb=%p, ast=%p, bast=%p, "
581                              "astdata=%p\n", lock->lksb, lock->ast,
582                              lock->bast, lock->astdata);
583                         goto error;
584                 }
585 retry_convert:
586                 dlm_wait_for_recovery(dlm);
587
588                 if (res->owner == dlm->node_num)
589                         status = dlmconvert_master(dlm, res, lock, flags, mode);
590                 else
591                         status = dlmconvert_remote(dlm, res, lock, flags, mode);
592                 if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
593                     status == DLM_FORWARD) {
594                         /* for now, see how this works without sleeping
595                          * and just retry right away.  I suspect the reco
596                          * or migration will complete fast enough that
597                          * no waiting will be necessary */
598                         mlog(0, "retrying convert with migration/recovery/"
599                              "in-progress\n");
600                         msleep(100);
601                         goto retry_convert;
602                 }
603         } else {
604                 u64 tmpcookie;
605
606                 /* LOCK request */
607                 status = DLM_BADARGS;
608                 if (!name) {
609                         dlm_error(status);
610                         goto error;
611                 }
612
613                 status = DLM_IVBUFLEN;
614                 if (strlen(name) > DLM_LOCKID_NAME_MAX || strlen(name) < 1) {
615                         dlm_error(status);
616                         goto error;
617                 }
618
619                 dlm_get_next_cookie(dlm->node_num, &tmpcookie);
620                 lock = dlm_new_lock(mode, dlm->node_num, tmpcookie, lksb);
621                 if (!lock) {
622                         dlm_error(status);
623                         goto error;
624                 }
625
626                 if (!recovery)
627                         dlm_wait_for_recovery(dlm);
628
629                 /* find or create the lock resource */
630                 res = dlm_get_lock_resource(dlm, name, flags);
631                 if (!res) {
632                         status = DLM_IVLOCKID;
633                         dlm_error(status);
634                         goto error;
635                 }
636
637                 mlog(0, "type=%d, flags = 0x%x\n", mode, flags);
638                 mlog(0, "creating lock: lock=%p res=%p\n", lock, res);
639
640                 dlm_lock_attach_lockres(lock, res);
641                 lock->ast = ast;
642                 lock->bast = bast;
643                 lock->astdata = data;
644
645 retry_lock:
646                 if (flags & LKM_VALBLK) {
647                         mlog(0, "LKM_VALBLK passed by caller\n");
648
649                         /* LVB requests for non PR, PW or EX locks are
650                          * ignored. */
651                         if (mode < LKM_PRMODE)
652                                 flags &= ~LKM_VALBLK;
653                         else {
654                                 flags |= LKM_GET_LVB;
655                                 lock->lksb->flags |= DLM_LKSB_GET_LVB;
656                         }
657                 }
658
659                 if (res->owner == dlm->node_num)
660                         status = dlmlock_master(dlm, res, lock, flags);
661                 else
662                         status = dlmlock_remote(dlm, res, lock, flags);
663
664                 if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
665                     status == DLM_FORWARD) {
666                         mlog(0, "retrying lock with migration/"
667                              "recovery/in progress\n");
668                         msleep(100);
669                         /* no waiting for dlm_reco_thread */
670                         if (recovery) {
671                                 if (status == DLM_RECOVERING) {
672                                         mlog(0, "%s: got RECOVERING "
673                                              "for $REOCVERY lock, master "
674                                              "was %u\n", dlm->name, 
675                                              res->owner);
676                                         dlm_wait_for_node_death(dlm, res->owner, 
677                                                         DLM_NODE_DEATH_WAIT_MAX);
678                                 }
679                         } else {
680                                 dlm_wait_for_recovery(dlm);
681                         }
682                         goto retry_lock;
683                 }
684
685                 if (status != DLM_NORMAL) {
686                         lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
687                         if (status != DLM_NOTQUEUED)
688                                 dlm_error(status);
689                         goto error;
690                 }
691         }
692
693 error:
694         if (status != DLM_NORMAL) {
695                 if (lock && !convert)
696                         dlm_lock_put(lock);
697                 // this is kind of unnecessary
698                 lksb->status = status;
699         }
700
701         /* put lockres ref from the convert path
702          * or from dlm_get_lock_resource */
703         if (res)
704                 dlm_lockres_put(res);
705
706         return status;
707 }
708 EXPORT_SYMBOL_GPL(dlmlock);