ocfs2/trivial: Remove trailing whitespaces
[linux-2.6.git] / fs / ocfs2 / dlm / dlmmaster.c
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * dlmmod.c
5  *
6  * standalone DLM module
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/init.h>
34 #include <linux/sysctl.h>
35 #include <linux/random.h>
36 #include <linux/blkdev.h>
37 #include <linux/socket.h>
38 #include <linux/inet.h>
39 #include <linux/spinlock.h>
40 #include <linux/delay.h>
41
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 #include "dlmdomain.h"
50 #include "dlmdebug.h"
51
52 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
53 #include "cluster/masklog.h"
54
55 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
56                               struct dlm_master_list_entry *mle,
57                               struct o2nm_node *node,
58                               int idx);
59 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
60                             struct dlm_master_list_entry *mle,
61                             struct o2nm_node *node,
62                             int idx);
63
64 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data);
65 static int dlm_do_assert_master(struct dlm_ctxt *dlm,
66                                 struct dlm_lock_resource *res,
67                                 void *nodemap, u32 flags);
68 static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data);
69
70 static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
71                                 struct dlm_master_list_entry *mle,
72                                 const char *name,
73                                 unsigned int namelen)
74 {
75         if (dlm != mle->dlm)
76                 return 0;
77
78         if (namelen != mle->mnamelen ||
79             memcmp(name, mle->mname, namelen) != 0)
80                 return 0;
81
82         return 1;
83 }
84
85 static struct kmem_cache *dlm_lockres_cache = NULL;
86 static struct kmem_cache *dlm_lockname_cache = NULL;
87 static struct kmem_cache *dlm_mle_cache = NULL;
88
89 static void dlm_mle_release(struct kref *kref);
90 static void dlm_init_mle(struct dlm_master_list_entry *mle,
91                         enum dlm_mle_type type,
92                         struct dlm_ctxt *dlm,
93                         struct dlm_lock_resource *res,
94                         const char *name,
95                         unsigned int namelen);
96 static void dlm_put_mle(struct dlm_master_list_entry *mle);
97 static void __dlm_put_mle(struct dlm_master_list_entry *mle);
98 static int dlm_find_mle(struct dlm_ctxt *dlm,
99                         struct dlm_master_list_entry **mle,
100                         char *name, unsigned int namelen);
101
102 static int dlm_do_master_request(struct dlm_lock_resource *res,
103                                  struct dlm_master_list_entry *mle, int to);
104
105
106 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
107                                      struct dlm_lock_resource *res,
108                                      struct dlm_master_list_entry *mle,
109                                      int *blocked);
110 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
111                                     struct dlm_lock_resource *res,
112                                     struct dlm_master_list_entry *mle,
113                                     int blocked);
114 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
115                                  struct dlm_lock_resource *res,
116                                  struct dlm_master_list_entry *mle,
117                                  struct dlm_master_list_entry **oldmle,
118                                  const char *name, unsigned int namelen,
119                                  u8 new_master, u8 master);
120
121 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
122                                     struct dlm_lock_resource *res);
123 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
124                                       struct dlm_lock_resource *res);
125 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
126                                        struct dlm_lock_resource *res,
127                                        u8 target);
128 static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
129                                        struct dlm_lock_resource *res);
130
131
132 int dlm_is_host_down(int errno)
133 {
134         switch (errno) {
135                 case -EBADF:
136                 case -ECONNREFUSED:
137                 case -ENOTCONN:
138                 case -ECONNRESET:
139                 case -EPIPE:
140                 case -EHOSTDOWN:
141                 case -EHOSTUNREACH:
142                 case -ETIMEDOUT:
143                 case -ECONNABORTED:
144                 case -ENETDOWN:
145                 case -ENETUNREACH:
146                 case -ENETRESET:
147                 case -ESHUTDOWN:
148                 case -ENOPROTOOPT:
149                 case -EINVAL:   /* if returned from our tcp code,
150                                    this means there is no socket */
151                         return 1;
152         }
153         return 0;
154 }
155
156
157 /*
158  * MASTER LIST FUNCTIONS
159  */
160
161
162 /*
163  * regarding master list entries and heartbeat callbacks:
164  *
165  * in order to avoid sleeping and allocation that occurs in
166  * heartbeat, master list entries are simply attached to the
167  * dlm's established heartbeat callbacks.  the mle is attached
168  * when it is created, and since the dlm->spinlock is held at
169  * that time, any heartbeat event will be properly discovered
170  * by the mle.  the mle needs to be detached from the
171  * dlm->mle_hb_events list as soon as heartbeat events are no
172  * longer useful to the mle, and before the mle is freed.
173  *
174  * as a general rule, heartbeat events are no longer needed by
175  * the mle once an "answer" regarding the lock master has been
176  * received.
177  */
178 static inline void __dlm_mle_attach_hb_events(struct dlm_ctxt *dlm,
179                                               struct dlm_master_list_entry *mle)
180 {
181         assert_spin_locked(&dlm->spinlock);
182
183         list_add_tail(&mle->hb_events, &dlm->mle_hb_events);
184 }
185
186
187 static inline void __dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
188                                               struct dlm_master_list_entry *mle)
189 {
190         if (!list_empty(&mle->hb_events))
191                 list_del_init(&mle->hb_events);
192 }
193
194
195 static inline void dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
196                                             struct dlm_master_list_entry *mle)
197 {
198         spin_lock(&dlm->spinlock);
199         __dlm_mle_detach_hb_events(dlm, mle);
200         spin_unlock(&dlm->spinlock);
201 }
202
203 static void dlm_get_mle_inuse(struct dlm_master_list_entry *mle)
204 {
205         struct dlm_ctxt *dlm;
206         dlm = mle->dlm;
207
208         assert_spin_locked(&dlm->spinlock);
209         assert_spin_locked(&dlm->master_lock);
210         mle->inuse++;
211         kref_get(&mle->mle_refs);
212 }
213
214 static void dlm_put_mle_inuse(struct dlm_master_list_entry *mle)
215 {
216         struct dlm_ctxt *dlm;
217         dlm = mle->dlm;
218
219         spin_lock(&dlm->spinlock);
220         spin_lock(&dlm->master_lock);
221         mle->inuse--;
222         __dlm_put_mle(mle);
223         spin_unlock(&dlm->master_lock);
224         spin_unlock(&dlm->spinlock);
225
226 }
227
228 /* remove from list and free */
229 static void __dlm_put_mle(struct dlm_master_list_entry *mle)
230 {
231         struct dlm_ctxt *dlm;
232         dlm = mle->dlm;
233
234         assert_spin_locked(&dlm->spinlock);
235         assert_spin_locked(&dlm->master_lock);
236         if (!atomic_read(&mle->mle_refs.refcount)) {
237                 /* this may or may not crash, but who cares.
238                  * it's a BUG. */
239                 mlog(ML_ERROR, "bad mle: %p\n", mle);
240                 dlm_print_one_mle(mle);
241                 BUG();
242         } else
243                 kref_put(&mle->mle_refs, dlm_mle_release);
244 }
245
246
247 /* must not have any spinlocks coming in */
248 static void dlm_put_mle(struct dlm_master_list_entry *mle)
249 {
250         struct dlm_ctxt *dlm;
251         dlm = mle->dlm;
252
253         spin_lock(&dlm->spinlock);
254         spin_lock(&dlm->master_lock);
255         __dlm_put_mle(mle);
256         spin_unlock(&dlm->master_lock);
257         spin_unlock(&dlm->spinlock);
258 }
259
260 static inline void dlm_get_mle(struct dlm_master_list_entry *mle)
261 {
262         kref_get(&mle->mle_refs);
263 }
264
265 static void dlm_init_mle(struct dlm_master_list_entry *mle,
266                         enum dlm_mle_type type,
267                         struct dlm_ctxt *dlm,
268                         struct dlm_lock_resource *res,
269                         const char *name,
270                         unsigned int namelen)
271 {
272         assert_spin_locked(&dlm->spinlock);
273
274         mle->dlm = dlm;
275         mle->type = type;
276         INIT_HLIST_NODE(&mle->master_hash_node);
277         INIT_LIST_HEAD(&mle->hb_events);
278         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
279         spin_lock_init(&mle->spinlock);
280         init_waitqueue_head(&mle->wq);
281         atomic_set(&mle->woken, 0);
282         kref_init(&mle->mle_refs);
283         memset(mle->response_map, 0, sizeof(mle->response_map));
284         mle->master = O2NM_MAX_NODES;
285         mle->new_master = O2NM_MAX_NODES;
286         mle->inuse = 0;
287
288         BUG_ON(mle->type != DLM_MLE_BLOCK &&
289                mle->type != DLM_MLE_MASTER &&
290                mle->type != DLM_MLE_MIGRATION);
291
292         if (mle->type == DLM_MLE_MASTER) {
293                 BUG_ON(!res);
294                 mle->mleres = res;
295                 memcpy(mle->mname, res->lockname.name, res->lockname.len);
296                 mle->mnamelen = res->lockname.len;
297                 mle->mnamehash = res->lockname.hash;
298         } else {
299                 BUG_ON(!name);
300                 mle->mleres = NULL;
301                 memcpy(mle->mname, name, namelen);
302                 mle->mnamelen = namelen;
303                 mle->mnamehash = dlm_lockid_hash(name, namelen);
304         }
305
306         atomic_inc(&dlm->mle_tot_count[mle->type]);
307         atomic_inc(&dlm->mle_cur_count[mle->type]);
308
309         /* copy off the node_map and register hb callbacks on our copy */
310         memcpy(mle->node_map, dlm->domain_map, sizeof(mle->node_map));
311         memcpy(mle->vote_map, dlm->domain_map, sizeof(mle->vote_map));
312         clear_bit(dlm->node_num, mle->vote_map);
313         clear_bit(dlm->node_num, mle->node_map);
314
315         /* attach the mle to the domain node up/down events */
316         __dlm_mle_attach_hb_events(dlm, mle);
317 }
318
319 void __dlm_unlink_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle)
320 {
321         assert_spin_locked(&dlm->spinlock);
322         assert_spin_locked(&dlm->master_lock);
323
324         if (!hlist_unhashed(&mle->master_hash_node))
325                 hlist_del_init(&mle->master_hash_node);
326 }
327
328 void __dlm_insert_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle)
329 {
330         struct hlist_head *bucket;
331
332         assert_spin_locked(&dlm->master_lock);
333
334         bucket = dlm_master_hash(dlm, mle->mnamehash);
335         hlist_add_head(&mle->master_hash_node, bucket);
336 }
337
338 /* returns 1 if found, 0 if not */
339 static int dlm_find_mle(struct dlm_ctxt *dlm,
340                         struct dlm_master_list_entry **mle,
341                         char *name, unsigned int namelen)
342 {
343         struct dlm_master_list_entry *tmpmle;
344         struct hlist_head *bucket;
345         struct hlist_node *list;
346         unsigned int hash;
347
348         assert_spin_locked(&dlm->master_lock);
349
350         hash = dlm_lockid_hash(name, namelen);
351         bucket = dlm_master_hash(dlm, hash);
352         hlist_for_each(list, bucket) {
353                 tmpmle = hlist_entry(list, struct dlm_master_list_entry,
354                                      master_hash_node);
355                 if (!dlm_mle_equal(dlm, tmpmle, name, namelen))
356                         continue;
357                 dlm_get_mle(tmpmle);
358                 *mle = tmpmle;
359                 return 1;
360         }
361         return 0;
362 }
363
364 void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up)
365 {
366         struct dlm_master_list_entry *mle;
367
368         assert_spin_locked(&dlm->spinlock);
369
370         list_for_each_entry(mle, &dlm->mle_hb_events, hb_events) {
371                 if (node_up)
372                         dlm_mle_node_up(dlm, mle, NULL, idx);
373                 else
374                         dlm_mle_node_down(dlm, mle, NULL, idx);
375         }
376 }
377
378 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
379                               struct dlm_master_list_entry *mle,
380                               struct o2nm_node *node, int idx)
381 {
382         spin_lock(&mle->spinlock);
383
384         if (!test_bit(idx, mle->node_map))
385                 mlog(0, "node %u already removed from nodemap!\n", idx);
386         else
387                 clear_bit(idx, mle->node_map);
388
389         spin_unlock(&mle->spinlock);
390 }
391
392 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
393                             struct dlm_master_list_entry *mle,
394                             struct o2nm_node *node, int idx)
395 {
396         spin_lock(&mle->spinlock);
397
398         if (test_bit(idx, mle->node_map))
399                 mlog(0, "node %u already in node map!\n", idx);
400         else
401                 set_bit(idx, mle->node_map);
402
403         spin_unlock(&mle->spinlock);
404 }
405
406
407 int dlm_init_mle_cache(void)
408 {
409         dlm_mle_cache = kmem_cache_create("o2dlm_mle",
410                                           sizeof(struct dlm_master_list_entry),
411                                           0, SLAB_HWCACHE_ALIGN,
412                                           NULL);
413         if (dlm_mle_cache == NULL)
414                 return -ENOMEM;
415         return 0;
416 }
417
418 void dlm_destroy_mle_cache(void)
419 {
420         if (dlm_mle_cache)
421                 kmem_cache_destroy(dlm_mle_cache);
422 }
423
424 static void dlm_mle_release(struct kref *kref)
425 {
426         struct dlm_master_list_entry *mle;
427         struct dlm_ctxt *dlm;
428
429         mlog_entry_void();
430
431         mle = container_of(kref, struct dlm_master_list_entry, mle_refs);
432         dlm = mle->dlm;
433
434         assert_spin_locked(&dlm->spinlock);
435         assert_spin_locked(&dlm->master_lock);
436
437         mlog(0, "Releasing mle for %.*s, type %d\n", mle->mnamelen, mle->mname,
438              mle->type);
439
440         /* remove from list if not already */
441         __dlm_unlink_mle(dlm, mle);
442
443         /* detach the mle from the domain node up/down events */
444         __dlm_mle_detach_hb_events(dlm, mle);
445
446         atomic_dec(&dlm->mle_cur_count[mle->type]);
447
448         /* NOTE: kfree under spinlock here.
449          * if this is bad, we can move this to a freelist. */
450         kmem_cache_free(dlm_mle_cache, mle);
451 }
452
453
454 /*
455  * LOCK RESOURCE FUNCTIONS
456  */
457
458 int dlm_init_master_caches(void)
459 {
460         dlm_lockres_cache = kmem_cache_create("o2dlm_lockres",
461                                               sizeof(struct dlm_lock_resource),
462                                               0, SLAB_HWCACHE_ALIGN, NULL);
463         if (!dlm_lockres_cache)
464                 goto bail;
465
466         dlm_lockname_cache = kmem_cache_create("o2dlm_lockname",
467                                                DLM_LOCKID_NAME_MAX, 0,
468                                                SLAB_HWCACHE_ALIGN, NULL);
469         if (!dlm_lockname_cache)
470                 goto bail;
471
472         return 0;
473 bail:
474         dlm_destroy_master_caches();
475         return -ENOMEM;
476 }
477
478 void dlm_destroy_master_caches(void)
479 {
480         if (dlm_lockname_cache)
481                 kmem_cache_destroy(dlm_lockname_cache);
482
483         if (dlm_lockres_cache)
484                 kmem_cache_destroy(dlm_lockres_cache);
485 }
486
487 static void dlm_lockres_release(struct kref *kref)
488 {
489         struct dlm_lock_resource *res;
490         struct dlm_ctxt *dlm;
491
492         res = container_of(kref, struct dlm_lock_resource, refs);
493         dlm = res->dlm;
494
495         /* This should not happen -- all lockres' have a name
496          * associated with them at init time. */
497         BUG_ON(!res->lockname.name);
498
499         mlog(0, "destroying lockres %.*s\n", res->lockname.len,
500              res->lockname.name);
501
502         spin_lock(&dlm->track_lock);
503         if (!list_empty(&res->tracking))
504                 list_del_init(&res->tracking);
505         else {
506                 mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n",
507                      res->lockname.len, res->lockname.name);
508                 dlm_print_one_lock_resource(res);
509         }
510         spin_unlock(&dlm->track_lock);
511
512         atomic_dec(&dlm->res_cur_count);
513
514         dlm_put(dlm);
515
516         if (!hlist_unhashed(&res->hash_node) ||
517             !list_empty(&res->granted) ||
518             !list_empty(&res->converting) ||
519             !list_empty(&res->blocked) ||
520             !list_empty(&res->dirty) ||
521             !list_empty(&res->recovering) ||
522             !list_empty(&res->purge)) {
523                 mlog(ML_ERROR,
524                      "Going to BUG for resource %.*s."
525                      "  We're on a list! [%c%c%c%c%c%c%c]\n",
526                      res->lockname.len, res->lockname.name,
527                      !hlist_unhashed(&res->hash_node) ? 'H' : ' ',
528                      !list_empty(&res->granted) ? 'G' : ' ',
529                      !list_empty(&res->converting) ? 'C' : ' ',
530                      !list_empty(&res->blocked) ? 'B' : ' ',
531                      !list_empty(&res->dirty) ? 'D' : ' ',
532                      !list_empty(&res->recovering) ? 'R' : ' ',
533                      !list_empty(&res->purge) ? 'P' : ' ');
534
535                 dlm_print_one_lock_resource(res);
536         }
537
538         /* By the time we're ready to blow this guy away, we shouldn't
539          * be on any lists. */
540         BUG_ON(!hlist_unhashed(&res->hash_node));
541         BUG_ON(!list_empty(&res->granted));
542         BUG_ON(!list_empty(&res->converting));
543         BUG_ON(!list_empty(&res->blocked));
544         BUG_ON(!list_empty(&res->dirty));
545         BUG_ON(!list_empty(&res->recovering));
546         BUG_ON(!list_empty(&res->purge));
547
548         kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
549
550         kmem_cache_free(dlm_lockres_cache, res);
551 }
552
553 void dlm_lockres_put(struct dlm_lock_resource *res)
554 {
555         kref_put(&res->refs, dlm_lockres_release);
556 }
557
558 static void dlm_init_lockres(struct dlm_ctxt *dlm,
559                              struct dlm_lock_resource *res,
560                              const char *name, unsigned int namelen)
561 {
562         char *qname;
563
564         /* If we memset here, we lose our reference to the kmalloc'd
565          * res->lockname.name, so be sure to init every field
566          * correctly! */
567
568         qname = (char *) res->lockname.name;
569         memcpy(qname, name, namelen);
570
571         res->lockname.len = namelen;
572         res->lockname.hash = dlm_lockid_hash(name, namelen);
573
574         init_waitqueue_head(&res->wq);
575         spin_lock_init(&res->spinlock);
576         INIT_HLIST_NODE(&res->hash_node);
577         INIT_LIST_HEAD(&res->granted);
578         INIT_LIST_HEAD(&res->converting);
579         INIT_LIST_HEAD(&res->blocked);
580         INIT_LIST_HEAD(&res->dirty);
581         INIT_LIST_HEAD(&res->recovering);
582         INIT_LIST_HEAD(&res->purge);
583         INIT_LIST_HEAD(&res->tracking);
584         atomic_set(&res->asts_reserved, 0);
585         res->migration_pending = 0;
586         res->inflight_locks = 0;
587
588         /* put in dlm_lockres_release */
589         dlm_grab(dlm);
590         res->dlm = dlm;
591
592         kref_init(&res->refs);
593
594         atomic_inc(&dlm->res_tot_count);
595         atomic_inc(&dlm->res_cur_count);
596
597         /* just for consistency */
598         spin_lock(&res->spinlock);
599         dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
600         spin_unlock(&res->spinlock);
601
602         res->state = DLM_LOCK_RES_IN_PROGRESS;
603
604         res->last_used = 0;
605
606         spin_lock(&dlm->spinlock);
607         list_add_tail(&res->tracking, &dlm->tracking_list);
608         spin_unlock(&dlm->spinlock);
609
610         memset(res->lvb, 0, DLM_LVB_LEN);
611         memset(res->refmap, 0, sizeof(res->refmap));
612 }
613
614 struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
615                                    const char *name,
616                                    unsigned int namelen)
617 {
618         struct dlm_lock_resource *res = NULL;
619
620         res = (struct dlm_lock_resource *)
621                                 kmem_cache_zalloc(dlm_lockres_cache, GFP_NOFS);
622         if (!res)
623                 goto error;
624
625         res->lockname.name = (char *)
626                                 kmem_cache_zalloc(dlm_lockname_cache, GFP_NOFS);
627         if (!res->lockname.name)
628                 goto error;
629
630         dlm_init_lockres(dlm, res, name, namelen);
631         return res;
632
633 error:
634         if (res && res->lockname.name)
635                 kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
636
637         if (res)
638                 kmem_cache_free(dlm_lockres_cache, res);
639         return NULL;
640 }
641
642 void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
643                                    struct dlm_lock_resource *res,
644                                    int new_lockres,
645                                    const char *file,
646                                    int line)
647 {
648         if (!new_lockres)
649                 assert_spin_locked(&res->spinlock);
650
651         if (!test_bit(dlm->node_num, res->refmap)) {
652                 BUG_ON(res->inflight_locks != 0);
653                 dlm_lockres_set_refmap_bit(dlm->node_num, res);
654         }
655         res->inflight_locks++;
656         mlog(0, "%s:%.*s: inflight++: now %u\n",
657              dlm->name, res->lockname.len, res->lockname.name,
658              res->inflight_locks);
659 }
660
661 void __dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
662                                    struct dlm_lock_resource *res,
663                                    const char *file,
664                                    int line)
665 {
666         assert_spin_locked(&res->spinlock);
667
668         BUG_ON(res->inflight_locks == 0);
669         res->inflight_locks--;
670         mlog(0, "%s:%.*s: inflight--: now %u\n",
671              dlm->name, res->lockname.len, res->lockname.name,
672              res->inflight_locks);
673         if (res->inflight_locks == 0)
674                 dlm_lockres_clear_refmap_bit(dlm->node_num, res);
675         wake_up(&res->wq);
676 }
677
678 /*
679  * lookup a lock resource by name.
680  * may already exist in the hashtable.
681  * lockid is null terminated
682  *
683  * if not, allocate enough for the lockres and for
684  * the temporary structure used in doing the mastering.
685  *
686  * also, do a lookup in the dlm->master_list to see
687  * if another node has begun mastering the same lock.
688  * if so, there should be a block entry in there
689  * for this name, and we should *not* attempt to master
690  * the lock here.   need to wait around for that node
691  * to assert_master (or die).
692  *
693  */
694 struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm,
695                                           const char *lockid,
696                                           int namelen,
697                                           int flags)
698 {
699         struct dlm_lock_resource *tmpres=NULL, *res=NULL;
700         struct dlm_master_list_entry *mle = NULL;
701         struct dlm_master_list_entry *alloc_mle = NULL;
702         int blocked = 0;
703         int ret, nodenum;
704         struct dlm_node_iter iter;
705         unsigned int hash;
706         int tries = 0;
707         int bit, wait_on_recovery = 0;
708         int drop_inflight_if_nonlocal = 0;
709
710         BUG_ON(!lockid);
711
712         hash = dlm_lockid_hash(lockid, namelen);
713
714         mlog(0, "get lockres %s (len %d)\n", lockid, namelen);
715
716 lookup:
717         spin_lock(&dlm->spinlock);
718         tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash);
719         if (tmpres) {
720                 int dropping_ref = 0;
721
722                 spin_unlock(&dlm->spinlock);
723
724                 spin_lock(&tmpres->spinlock);
725                 /* We wait for the other thread that is mastering the resource */
726                 if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
727                         __dlm_wait_on_lockres(tmpres);
728                         BUG_ON(tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN);
729                 }
730
731                 if (tmpres->owner == dlm->node_num) {
732                         BUG_ON(tmpres->state & DLM_LOCK_RES_DROPPING_REF);
733                         dlm_lockres_grab_inflight_ref(dlm, tmpres);
734                 } else if (tmpres->state & DLM_LOCK_RES_DROPPING_REF)
735                         dropping_ref = 1;
736                 spin_unlock(&tmpres->spinlock);
737
738                 /* wait until done messaging the master, drop our ref to allow
739                  * the lockres to be purged, start over. */
740                 if (dropping_ref) {
741                         spin_lock(&tmpres->spinlock);
742                         __dlm_wait_on_lockres_flags(tmpres, DLM_LOCK_RES_DROPPING_REF);
743                         spin_unlock(&tmpres->spinlock);
744                         dlm_lockres_put(tmpres);
745                         tmpres = NULL;
746                         goto lookup;
747                 }
748
749                 mlog(0, "found in hash!\n");
750                 if (res)
751                         dlm_lockres_put(res);
752                 res = tmpres;
753                 goto leave;
754         }
755
756         if (!res) {
757                 spin_unlock(&dlm->spinlock);
758                 mlog(0, "allocating a new resource\n");
759                 /* nothing found and we need to allocate one. */
760                 alloc_mle = (struct dlm_master_list_entry *)
761                         kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
762                 if (!alloc_mle)
763                         goto leave;
764                 res = dlm_new_lockres(dlm, lockid, namelen);
765                 if (!res)
766                         goto leave;
767                 goto lookup;
768         }
769
770         mlog(0, "no lockres found, allocated our own: %p\n", res);
771
772         if (flags & LKM_LOCAL) {
773                 /* caller knows it's safe to assume it's not mastered elsewhere
774                  * DONE!  return right away */
775                 spin_lock(&res->spinlock);
776                 dlm_change_lockres_owner(dlm, res, dlm->node_num);
777                 __dlm_insert_lockres(dlm, res);
778                 dlm_lockres_grab_inflight_ref(dlm, res);
779                 spin_unlock(&res->spinlock);
780                 spin_unlock(&dlm->spinlock);
781                 /* lockres still marked IN_PROGRESS */
782                 goto wake_waiters;
783         }
784
785         /* check master list to see if another node has started mastering it */
786         spin_lock(&dlm->master_lock);
787
788         /* if we found a block, wait for lock to be mastered by another node */
789         blocked = dlm_find_mle(dlm, &mle, (char *)lockid, namelen);
790         if (blocked) {
791                 int mig;
792                 if (mle->type == DLM_MLE_MASTER) {
793                         mlog(ML_ERROR, "master entry for nonexistent lock!\n");
794                         BUG();
795                 }
796                 mig = (mle->type == DLM_MLE_MIGRATION);
797                 /* if there is a migration in progress, let the migration
798                  * finish before continuing.  we can wait for the absence
799                  * of the MIGRATION mle: either the migrate finished or
800                  * one of the nodes died and the mle was cleaned up.
801                  * if there is a BLOCK here, but it already has a master
802                  * set, we are too late.  the master does not have a ref
803                  * for us in the refmap.  detach the mle and drop it.
804                  * either way, go back to the top and start over. */
805                 if (mig || mle->master != O2NM_MAX_NODES) {
806                         BUG_ON(mig && mle->master == dlm->node_num);
807                         /* we arrived too late.  the master does not
808                          * have a ref for us. retry. */
809                         mlog(0, "%s:%.*s: late on %s\n",
810                              dlm->name, namelen, lockid,
811                              mig ?  "MIGRATION" : "BLOCK");
812                         spin_unlock(&dlm->master_lock);
813                         spin_unlock(&dlm->spinlock);
814
815                         /* master is known, detach */
816                         if (!mig)
817                                 dlm_mle_detach_hb_events(dlm, mle);
818                         dlm_put_mle(mle);
819                         mle = NULL;
820                         /* this is lame, but we cant wait on either
821                          * the mle or lockres waitqueue here */
822                         if (mig)
823                                 msleep(100);
824                         goto lookup;
825                 }
826         } else {
827                 /* go ahead and try to master lock on this node */
828                 mle = alloc_mle;
829                 /* make sure this does not get freed below */
830                 alloc_mle = NULL;
831                 dlm_init_mle(mle, DLM_MLE_MASTER, dlm, res, NULL, 0);
832                 set_bit(dlm->node_num, mle->maybe_map);
833                 __dlm_insert_mle(dlm, mle);
834
835                 /* still holding the dlm spinlock, check the recovery map
836                  * to see if there are any nodes that still need to be
837                  * considered.  these will not appear in the mle nodemap
838                  * but they might own this lockres.  wait on them. */
839                 bit = find_next_bit(dlm->recovery_map, O2NM_MAX_NODES, 0);
840                 if (bit < O2NM_MAX_NODES) {
841                         mlog(ML_NOTICE, "%s:%.*s: at least one node (%d) to "
842                              "recover before lock mastery can begin\n",
843                              dlm->name, namelen, (char *)lockid, bit);
844                         wait_on_recovery = 1;
845                 }
846         }
847
848         /* at this point there is either a DLM_MLE_BLOCK or a
849          * DLM_MLE_MASTER on the master list, so it's safe to add the
850          * lockres to the hashtable.  anyone who finds the lock will
851          * still have to wait on the IN_PROGRESS. */
852
853         /* finally add the lockres to its hash bucket */
854         __dlm_insert_lockres(dlm, res);
855         /* since this lockres is new it doesnt not require the spinlock */
856         dlm_lockres_grab_inflight_ref_new(dlm, res);
857
858         /* if this node does not become the master make sure to drop
859          * this inflight reference below */
860         drop_inflight_if_nonlocal = 1;
861
862         /* get an extra ref on the mle in case this is a BLOCK
863          * if so, the creator of the BLOCK may try to put the last
864          * ref at this time in the assert master handler, so we
865          * need an extra one to keep from a bad ptr deref. */
866         dlm_get_mle_inuse(mle);
867         spin_unlock(&dlm->master_lock);
868         spin_unlock(&dlm->spinlock);
869
870 redo_request:
871         while (wait_on_recovery) {
872                 /* any cluster changes that occurred after dropping the
873                  * dlm spinlock would be detectable be a change on the mle,
874                  * so we only need to clear out the recovery map once. */
875                 if (dlm_is_recovery_lock(lockid, namelen)) {
876                         mlog(ML_NOTICE, "%s: recovery map is not empty, but "
877                              "must master $RECOVERY lock now\n", dlm->name);
878                         if (!dlm_pre_master_reco_lockres(dlm, res))
879                                 wait_on_recovery = 0;
880                         else {
881                                 mlog(0, "%s: waiting 500ms for heartbeat state "
882                                     "change\n", dlm->name);
883                                 msleep(500);
884                         }
885                         continue;
886                 }
887
888                 dlm_kick_recovery_thread(dlm);
889                 msleep(1000);
890                 dlm_wait_for_recovery(dlm);
891
892                 spin_lock(&dlm->spinlock);
893                 bit = find_next_bit(dlm->recovery_map, O2NM_MAX_NODES, 0);
894                 if (bit < O2NM_MAX_NODES) {
895                         mlog(ML_NOTICE, "%s:%.*s: at least one node (%d) to "
896                              "recover before lock mastery can begin\n",
897                              dlm->name, namelen, (char *)lockid, bit);
898                         wait_on_recovery = 1;
899                 } else
900                         wait_on_recovery = 0;
901                 spin_unlock(&dlm->spinlock);
902
903                 if (wait_on_recovery)
904                         dlm_wait_for_node_recovery(dlm, bit, 10000);
905         }
906
907         /* must wait for lock to be mastered elsewhere */
908         if (blocked)
909                 goto wait;
910
911         ret = -EINVAL;
912         dlm_node_iter_init(mle->vote_map, &iter);
913         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
914                 ret = dlm_do_master_request(res, mle, nodenum);
915                 if (ret < 0)
916                         mlog_errno(ret);
917                 if (mle->master != O2NM_MAX_NODES) {
918                         /* found a master ! */
919                         if (mle->master <= nodenum)
920                                 break;
921                         /* if our master request has not reached the master
922                          * yet, keep going until it does.  this is how the
923                          * master will know that asserts are needed back to
924                          * the lower nodes. */
925                         mlog(0, "%s:%.*s: requests only up to %u but master "
926                              "is %u, keep going\n", dlm->name, namelen,
927                              lockid, nodenum, mle->master);
928                 }
929         }
930
931 wait:
932         /* keep going until the response map includes all nodes */
933         ret = dlm_wait_for_lock_mastery(dlm, res, mle, &blocked);
934         if (ret < 0) {
935                 wait_on_recovery = 1;
936                 mlog(0, "%s:%.*s: node map changed, redo the "
937                      "master request now, blocked=%d\n",
938                      dlm->name, res->lockname.len,
939                      res->lockname.name, blocked);
940                 if (++tries > 20) {
941                         mlog(ML_ERROR, "%s:%.*s: spinning on "
942                              "dlm_wait_for_lock_mastery, blocked=%d\n",
943                              dlm->name, res->lockname.len,
944                              res->lockname.name, blocked);
945                         dlm_print_one_lock_resource(res);
946                         dlm_print_one_mle(mle);
947                         tries = 0;
948                 }
949                 goto redo_request;
950         }
951
952         mlog(0, "lockres mastered by %u\n", res->owner);
953         /* make sure we never continue without this */
954         BUG_ON(res->owner == O2NM_MAX_NODES);
955
956         /* master is known, detach if not already detached */
957         dlm_mle_detach_hb_events(dlm, mle);
958         dlm_put_mle(mle);
959         /* put the extra ref */
960         dlm_put_mle_inuse(mle);
961
962 wake_waiters:
963         spin_lock(&res->spinlock);
964         if (res->owner != dlm->node_num && drop_inflight_if_nonlocal)
965                 dlm_lockres_drop_inflight_ref(dlm, res);
966         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
967         spin_unlock(&res->spinlock);
968         wake_up(&res->wq);
969
970 leave:
971         /* need to free the unused mle */
972         if (alloc_mle)
973                 kmem_cache_free(dlm_mle_cache, alloc_mle);
974
975         return res;
976 }
977
978
979 #define DLM_MASTERY_TIMEOUT_MS   5000
980
981 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
982                                      struct dlm_lock_resource *res,
983                                      struct dlm_master_list_entry *mle,
984                                      int *blocked)
985 {
986         u8 m;
987         int ret, bit;
988         int map_changed, voting_done;
989         int assert, sleep;
990
991 recheck:
992         ret = 0;
993         assert = 0;
994
995         /* check if another node has already become the owner */
996         spin_lock(&res->spinlock);
997         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
998                 mlog(0, "%s:%.*s: owner is suddenly %u\n", dlm->name,
999                      res->lockname.len, res->lockname.name, res->owner);
1000                 spin_unlock(&res->spinlock);
1001                 /* this will cause the master to re-assert across
1002                  * the whole cluster, freeing up mles */
1003                 if (res->owner != dlm->node_num) {
1004                         ret = dlm_do_master_request(res, mle, res->owner);
1005                         if (ret < 0) {
1006                                 /* give recovery a chance to run */
1007                                 mlog(ML_ERROR, "link to %u went down?: %d\n", res->owner, ret);
1008                                 msleep(500);
1009                                 goto recheck;
1010                         }
1011                 }
1012                 ret = 0;
1013                 goto leave;
1014         }
1015         spin_unlock(&res->spinlock);
1016
1017         spin_lock(&mle->spinlock);
1018         m = mle->master;
1019         map_changed = (memcmp(mle->vote_map, mle->node_map,
1020                               sizeof(mle->vote_map)) != 0);
1021         voting_done = (memcmp(mle->vote_map, mle->response_map,
1022                              sizeof(mle->vote_map)) == 0);
1023
1024         /* restart if we hit any errors */
1025         if (map_changed) {
1026                 int b;
1027                 mlog(0, "%s: %.*s: node map changed, restarting\n",
1028                      dlm->name, res->lockname.len, res->lockname.name);
1029                 ret = dlm_restart_lock_mastery(dlm, res, mle, *blocked);
1030                 b = (mle->type == DLM_MLE_BLOCK);
1031                 if ((*blocked && !b) || (!*blocked && b)) {
1032                         mlog(0, "%s:%.*s: status change: old=%d new=%d\n",
1033                              dlm->name, res->lockname.len, res->lockname.name,
1034                              *blocked, b);
1035                         *blocked = b;
1036                 }
1037                 spin_unlock(&mle->spinlock);
1038                 if (ret < 0) {
1039                         mlog_errno(ret);
1040                         goto leave;
1041                 }
1042                 mlog(0, "%s:%.*s: restart lock mastery succeeded, "
1043                      "rechecking now\n", dlm->name, res->lockname.len,
1044                      res->lockname.name);
1045                 goto recheck;
1046         } else {
1047                 if (!voting_done) {
1048                         mlog(0, "map not changed and voting not done "
1049                              "for %s:%.*s\n", dlm->name, res->lockname.len,
1050                              res->lockname.name);
1051                 }
1052         }
1053
1054         if (m != O2NM_MAX_NODES) {
1055                 /* another node has done an assert!
1056                  * all done! */
1057                 sleep = 0;
1058         } else {
1059                 sleep = 1;
1060                 /* have all nodes responded? */
1061                 if (voting_done && !*blocked) {
1062                         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
1063                         if (dlm->node_num <= bit) {
1064                                 /* my node number is lowest.
1065                                  * now tell other nodes that I am
1066                                  * mastering this. */
1067                                 mle->master = dlm->node_num;
1068                                 /* ref was grabbed in get_lock_resource
1069                                  * will be dropped in dlmlock_master */
1070                                 assert = 1;
1071                                 sleep = 0;
1072                         }
1073                         /* if voting is done, but we have not received
1074                          * an assert master yet, we must sleep */
1075                 }
1076         }
1077
1078         spin_unlock(&mle->spinlock);
1079
1080         /* sleep if we haven't finished voting yet */
1081         if (sleep) {
1082                 unsigned long timeo = msecs_to_jiffies(DLM_MASTERY_TIMEOUT_MS);
1083
1084                 /*
1085                 if (atomic_read(&mle->mle_refs.refcount) < 2)
1086                         mlog(ML_ERROR, "mle (%p) refs=%d, name=%.*s\n", mle,
1087                         atomic_read(&mle->mle_refs.refcount),
1088                         res->lockname.len, res->lockname.name);
1089                 */
1090                 atomic_set(&mle->woken, 0);
1091                 (void)wait_event_timeout(mle->wq,
1092                                          (atomic_read(&mle->woken) == 1),
1093                                          timeo);
1094                 if (res->owner == O2NM_MAX_NODES) {
1095                         mlog(0, "%s:%.*s: waiting again\n", dlm->name,
1096                              res->lockname.len, res->lockname.name);
1097                         goto recheck;
1098                 }
1099                 mlog(0, "done waiting, master is %u\n", res->owner);
1100                 ret = 0;
1101                 goto leave;
1102         }
1103
1104         ret = 0;   /* done */
1105         if (assert) {
1106                 m = dlm->node_num;
1107                 mlog(0, "about to master %.*s here, this=%u\n",
1108                      res->lockname.len, res->lockname.name, m);
1109                 ret = dlm_do_assert_master(dlm, res, mle->vote_map, 0);
1110                 if (ret) {
1111                         /* This is a failure in the network path,
1112                          * not in the response to the assert_master
1113                          * (any nonzero response is a BUG on this node).
1114                          * Most likely a socket just got disconnected
1115                          * due to node death. */
1116                         mlog_errno(ret);
1117                 }
1118                 /* no longer need to restart lock mastery.
1119                  * all living nodes have been contacted. */
1120                 ret = 0;
1121         }
1122
1123         /* set the lockres owner */
1124         spin_lock(&res->spinlock);
1125         /* mastery reference obtained either during
1126          * assert_master_handler or in get_lock_resource */
1127         dlm_change_lockres_owner(dlm, res, m);
1128         spin_unlock(&res->spinlock);
1129
1130 leave:
1131         return ret;
1132 }
1133
1134 struct dlm_bitmap_diff_iter
1135 {
1136         int curnode;
1137         unsigned long *orig_bm;
1138         unsigned long *cur_bm;
1139         unsigned long diff_bm[BITS_TO_LONGS(O2NM_MAX_NODES)];
1140 };
1141
1142 enum dlm_node_state_change
1143 {
1144         NODE_DOWN = -1,
1145         NODE_NO_CHANGE = 0,
1146         NODE_UP
1147 };
1148
1149 static void dlm_bitmap_diff_iter_init(struct dlm_bitmap_diff_iter *iter,
1150                                       unsigned long *orig_bm,
1151                                       unsigned long *cur_bm)
1152 {
1153         unsigned long p1, p2;
1154         int i;
1155
1156         iter->curnode = -1;
1157         iter->orig_bm = orig_bm;
1158         iter->cur_bm = cur_bm;
1159
1160         for (i = 0; i < BITS_TO_LONGS(O2NM_MAX_NODES); i++) {
1161                 p1 = *(iter->orig_bm + i);
1162                 p2 = *(iter->cur_bm + i);
1163                 iter->diff_bm[i] = (p1 & ~p2) | (p2 & ~p1);
1164         }
1165 }
1166
1167 static int dlm_bitmap_diff_iter_next(struct dlm_bitmap_diff_iter *iter,
1168                                      enum dlm_node_state_change *state)
1169 {
1170         int bit;
1171
1172         if (iter->curnode >= O2NM_MAX_NODES)
1173                 return -ENOENT;
1174
1175         bit = find_next_bit(iter->diff_bm, O2NM_MAX_NODES,
1176                             iter->curnode+1);
1177         if (bit >= O2NM_MAX_NODES) {
1178                 iter->curnode = O2NM_MAX_NODES;
1179                 return -ENOENT;
1180         }
1181
1182         /* if it was there in the original then this node died */
1183         if (test_bit(bit, iter->orig_bm))
1184                 *state = NODE_DOWN;
1185         else
1186                 *state = NODE_UP;
1187
1188         iter->curnode = bit;
1189         return bit;
1190 }
1191
1192
1193 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
1194                                     struct dlm_lock_resource *res,
1195                                     struct dlm_master_list_entry *mle,
1196                                     int blocked)
1197 {
1198         struct dlm_bitmap_diff_iter bdi;
1199         enum dlm_node_state_change sc;
1200         int node;
1201         int ret = 0;
1202
1203         mlog(0, "something happened such that the "
1204              "master process may need to be restarted!\n");
1205
1206         assert_spin_locked(&mle->spinlock);
1207
1208         dlm_bitmap_diff_iter_init(&bdi, mle->vote_map, mle->node_map);
1209         node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1210         while (node >= 0) {
1211                 if (sc == NODE_UP) {
1212                         /* a node came up.  clear any old vote from
1213                          * the response map and set it in the vote map
1214                          * then restart the mastery. */
1215                         mlog(ML_NOTICE, "node %d up while restarting\n", node);
1216
1217                         /* redo the master request, but only for the new node */
1218                         mlog(0, "sending request to new node\n");
1219                         clear_bit(node, mle->response_map);
1220                         set_bit(node, mle->vote_map);
1221                 } else {
1222                         mlog(ML_ERROR, "node down! %d\n", node);
1223                         if (blocked) {
1224                                 int lowest = find_next_bit(mle->maybe_map,
1225                                                        O2NM_MAX_NODES, 0);
1226
1227                                 /* act like it was never there */
1228                                 clear_bit(node, mle->maybe_map);
1229
1230                                 if (node == lowest) {
1231                                         mlog(0, "expected master %u died"
1232                                             " while this node was blocked "
1233                                             "waiting on it!\n", node);
1234                                         lowest = find_next_bit(mle->maybe_map,
1235                                                         O2NM_MAX_NODES,
1236                                                         lowest+1);
1237                                         if (lowest < O2NM_MAX_NODES) {
1238                                                 mlog(0, "%s:%.*s:still "
1239                                                      "blocked. waiting on %u "
1240                                                      "now\n", dlm->name,
1241                                                      res->lockname.len,
1242                                                      res->lockname.name,
1243                                                      lowest);
1244                                         } else {
1245                                                 /* mle is an MLE_BLOCK, but
1246                                                  * there is now nothing left to
1247                                                  * block on.  we need to return
1248                                                  * all the way back out and try
1249                                                  * again with an MLE_MASTER.
1250                                                  * dlm_do_local_recovery_cleanup
1251                                                  * has already run, so the mle
1252                                                  * refcount is ok */
1253                                                 mlog(0, "%s:%.*s: no "
1254                                                      "longer blocking. try to "
1255                                                      "master this here\n",
1256                                                      dlm->name,
1257                                                      res->lockname.len,
1258                                                      res->lockname.name);
1259                                                 mle->type = DLM_MLE_MASTER;
1260                                                 mle->mleres = res;
1261                                         }
1262                                 }
1263                         }
1264
1265                         /* now blank out everything, as if we had never
1266                          * contacted anyone */
1267                         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
1268                         memset(mle->response_map, 0, sizeof(mle->response_map));
1269                         /* reset the vote_map to the current node_map */
1270                         memcpy(mle->vote_map, mle->node_map,
1271                                sizeof(mle->node_map));
1272                         /* put myself into the maybe map */
1273                         if (mle->type != DLM_MLE_BLOCK)
1274                                 set_bit(dlm->node_num, mle->maybe_map);
1275                 }
1276                 ret = -EAGAIN;
1277                 node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1278         }
1279         return ret;
1280 }
1281
1282
1283 /*
1284  * DLM_MASTER_REQUEST_MSG
1285  *
1286  * returns: 0 on success,
1287  *          -errno on a network error
1288  *
1289  * on error, the caller should assume the target node is "dead"
1290  *
1291  */
1292
1293 static int dlm_do_master_request(struct dlm_lock_resource *res,
1294                                  struct dlm_master_list_entry *mle, int to)
1295 {
1296         struct dlm_ctxt *dlm = mle->dlm;
1297         struct dlm_master_request request;
1298         int ret, response=0, resend;
1299
1300         memset(&request, 0, sizeof(request));
1301         request.node_idx = dlm->node_num;
1302
1303         BUG_ON(mle->type == DLM_MLE_MIGRATION);
1304
1305         request.namelen = (u8)mle->mnamelen;
1306         memcpy(request.name, mle->mname, request.namelen);
1307
1308 again:
1309         ret = o2net_send_message(DLM_MASTER_REQUEST_MSG, dlm->key, &request,
1310                                  sizeof(request), to, &response);
1311         if (ret < 0)  {
1312                 if (ret == -ESRCH) {
1313                         /* should never happen */
1314                         mlog(ML_ERROR, "TCP stack not ready!\n");
1315                         BUG();
1316                 } else if (ret == -EINVAL) {
1317                         mlog(ML_ERROR, "bad args passed to o2net!\n");
1318                         BUG();
1319                 } else if (ret == -ENOMEM) {
1320                         mlog(ML_ERROR, "out of memory while trying to send "
1321                              "network message!  retrying\n");
1322                         /* this is totally crude */
1323                         msleep(50);
1324                         goto again;
1325                 } else if (!dlm_is_host_down(ret)) {
1326                         /* not a network error. bad. */
1327                         mlog_errno(ret);
1328                         mlog(ML_ERROR, "unhandled error!");
1329                         BUG();
1330                 }
1331                 /* all other errors should be network errors,
1332                  * and likely indicate node death */
1333                 mlog(ML_ERROR, "link to %d went down!\n", to);
1334                 goto out;
1335         }
1336
1337         ret = 0;
1338         resend = 0;
1339         spin_lock(&mle->spinlock);
1340         switch (response) {
1341                 case DLM_MASTER_RESP_YES:
1342                         set_bit(to, mle->response_map);
1343                         mlog(0, "node %u is the master, response=YES\n", to);
1344                         mlog(0, "%s:%.*s: master node %u now knows I have a "
1345                              "reference\n", dlm->name, res->lockname.len,
1346                              res->lockname.name, to);
1347                         mle->master = to;
1348                         break;
1349                 case DLM_MASTER_RESP_NO:
1350                         mlog(0, "node %u not master, response=NO\n", to);
1351                         set_bit(to, mle->response_map);
1352                         break;
1353                 case DLM_MASTER_RESP_MAYBE:
1354                         mlog(0, "node %u not master, response=MAYBE\n", to);
1355                         set_bit(to, mle->response_map);
1356                         set_bit(to, mle->maybe_map);
1357                         break;
1358                 case DLM_MASTER_RESP_ERROR:
1359                         mlog(0, "node %u hit an error, resending\n", to);
1360                         resend = 1;
1361                         response = 0;
1362                         break;
1363                 default:
1364                         mlog(ML_ERROR, "bad response! %u\n", response);
1365                         BUG();
1366         }
1367         spin_unlock(&mle->spinlock);
1368         if (resend) {
1369                 /* this is also totally crude */
1370                 msleep(50);
1371                 goto again;
1372         }
1373
1374 out:
1375         return ret;
1376 }
1377
1378 /*
1379  * locks that can be taken here:
1380  * dlm->spinlock
1381  * res->spinlock
1382  * mle->spinlock
1383  * dlm->master_list
1384  *
1385  * if possible, TRIM THIS DOWN!!!
1386  */
1387 int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data,
1388                                void **ret_data)
1389 {
1390         u8 response = DLM_MASTER_RESP_MAYBE;
1391         struct dlm_ctxt *dlm = data;
1392         struct dlm_lock_resource *res = NULL;
1393         struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
1394         struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
1395         char *name;
1396         unsigned int namelen, hash;
1397         int found, ret;
1398         int set_maybe;
1399         int dispatch_assert = 0;
1400
1401         if (!dlm_grab(dlm))
1402                 return DLM_MASTER_RESP_NO;
1403
1404         if (!dlm_domain_fully_joined(dlm)) {
1405                 response = DLM_MASTER_RESP_NO;
1406                 goto send_response;
1407         }
1408
1409         name = request->name;
1410         namelen = request->namelen;
1411         hash = dlm_lockid_hash(name, namelen);
1412
1413         if (namelen > DLM_LOCKID_NAME_MAX) {
1414                 response = DLM_IVBUFLEN;
1415                 goto send_response;
1416         }
1417
1418 way_up_top:
1419         spin_lock(&dlm->spinlock);
1420         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
1421         if (res) {
1422                 spin_unlock(&dlm->spinlock);
1423
1424                 /* take care of the easy cases up front */
1425                 spin_lock(&res->spinlock);
1426                 if (res->state & (DLM_LOCK_RES_RECOVERING|
1427                                   DLM_LOCK_RES_MIGRATING)) {
1428                         spin_unlock(&res->spinlock);
1429                         mlog(0, "returning DLM_MASTER_RESP_ERROR since res is "
1430                              "being recovered/migrated\n");
1431                         response = DLM_MASTER_RESP_ERROR;
1432                         if (mle)
1433                                 kmem_cache_free(dlm_mle_cache, mle);
1434                         goto send_response;
1435                 }
1436
1437                 if (res->owner == dlm->node_num) {
1438                         mlog(0, "%s:%.*s: setting bit %u in refmap\n",
1439                              dlm->name, namelen, name, request->node_idx);
1440                         dlm_lockres_set_refmap_bit(request->node_idx, res);
1441                         spin_unlock(&res->spinlock);
1442                         response = DLM_MASTER_RESP_YES;
1443                         if (mle)
1444                                 kmem_cache_free(dlm_mle_cache, mle);
1445
1446                         /* this node is the owner.
1447                          * there is some extra work that needs to
1448                          * happen now.  the requesting node has
1449                          * caused all nodes up to this one to
1450                          * create mles.  this node now needs to
1451                          * go back and clean those up. */
1452                         dispatch_assert = 1;
1453                         goto send_response;
1454                 } else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1455                         spin_unlock(&res->spinlock);
1456                         // mlog(0, "node %u is the master\n", res->owner);
1457                         response = DLM_MASTER_RESP_NO;
1458                         if (mle)
1459                                 kmem_cache_free(dlm_mle_cache, mle);
1460                         goto send_response;
1461                 }
1462
1463                 /* ok, there is no owner.  either this node is
1464                  * being blocked, or it is actively trying to
1465                  * master this lock. */
1466                 if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1467                         mlog(ML_ERROR, "lock with no owner should be "
1468                              "in-progress!\n");
1469                         BUG();
1470                 }
1471
1472                 // mlog(0, "lockres is in progress...\n");
1473                 spin_lock(&dlm->master_lock);
1474                 found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1475                 if (!found) {
1476                         mlog(ML_ERROR, "no mle found for this lock!\n");
1477                         BUG();
1478                 }
1479                 set_maybe = 1;
1480                 spin_lock(&tmpmle->spinlock);
1481                 if (tmpmle->type == DLM_MLE_BLOCK) {
1482                         // mlog(0, "this node is waiting for "
1483                         // "lockres to be mastered\n");
1484                         response = DLM_MASTER_RESP_NO;
1485                 } else if (tmpmle->type == DLM_MLE_MIGRATION) {
1486                         mlog(0, "node %u is master, but trying to migrate to "
1487                              "node %u.\n", tmpmle->master, tmpmle->new_master);
1488                         if (tmpmle->master == dlm->node_num) {
1489                                 mlog(ML_ERROR, "no owner on lockres, but this "
1490                                      "node is trying to migrate it to %u?!\n",
1491                                      tmpmle->new_master);
1492                                 BUG();
1493                         } else {
1494                                 /* the real master can respond on its own */
1495                                 response = DLM_MASTER_RESP_NO;
1496                         }
1497                 } else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
1498                         set_maybe = 0;
1499                         if (tmpmle->master == dlm->node_num) {
1500                                 response = DLM_MASTER_RESP_YES;
1501                                 /* this node will be the owner.
1502                                  * go back and clean the mles on any
1503                                  * other nodes */
1504                                 dispatch_assert = 1;
1505                                 dlm_lockres_set_refmap_bit(request->node_idx, res);
1506                                 mlog(0, "%s:%.*s: setting bit %u in refmap\n",
1507                                      dlm->name, namelen, name,
1508                                      request->node_idx);
1509                         } else
1510                                 response = DLM_MASTER_RESP_NO;
1511                 } else {
1512                         // mlog(0, "this node is attempting to "
1513                         // "master lockres\n");
1514                         response = DLM_MASTER_RESP_MAYBE;
1515                 }
1516                 if (set_maybe)
1517                         set_bit(request->node_idx, tmpmle->maybe_map);
1518                 spin_unlock(&tmpmle->spinlock);
1519
1520                 spin_unlock(&dlm->master_lock);
1521                 spin_unlock(&res->spinlock);
1522
1523                 /* keep the mle attached to heartbeat events */
1524                 dlm_put_mle(tmpmle);
1525                 if (mle)
1526                         kmem_cache_free(dlm_mle_cache, mle);
1527                 goto send_response;
1528         }
1529
1530         /*
1531          * lockres doesn't exist on this node
1532          * if there is an MLE_BLOCK, return NO
1533          * if there is an MLE_MASTER, return MAYBE
1534          * otherwise, add an MLE_BLOCK, return NO
1535          */
1536         spin_lock(&dlm->master_lock);
1537         found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1538         if (!found) {
1539                 /* this lockid has never been seen on this node yet */
1540                 // mlog(0, "no mle found\n");
1541                 if (!mle) {
1542                         spin_unlock(&dlm->master_lock);
1543                         spin_unlock(&dlm->spinlock);
1544
1545                         mle = (struct dlm_master_list_entry *)
1546                                 kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
1547                         if (!mle) {
1548                                 response = DLM_MASTER_RESP_ERROR;
1549                                 mlog_errno(-ENOMEM);
1550                                 goto send_response;
1551                         }
1552                         goto way_up_top;
1553                 }
1554
1555                 // mlog(0, "this is second time thru, already allocated, "
1556                 // "add the block.\n");
1557                 dlm_init_mle(mle, DLM_MLE_BLOCK, dlm, NULL, name, namelen);
1558                 set_bit(request->node_idx, mle->maybe_map);
1559                 __dlm_insert_mle(dlm, mle);
1560                 response = DLM_MASTER_RESP_NO;
1561         } else {
1562                 // mlog(0, "mle was found\n");
1563                 set_maybe = 1;
1564                 spin_lock(&tmpmle->spinlock);
1565                 if (tmpmle->master == dlm->node_num) {
1566                         mlog(ML_ERROR, "no lockres, but an mle with this node as master!\n");
1567                         BUG();
1568                 }
1569                 if (tmpmle->type == DLM_MLE_BLOCK)
1570                         response = DLM_MASTER_RESP_NO;
1571                 else if (tmpmle->type == DLM_MLE_MIGRATION) {
1572                         mlog(0, "migration mle was found (%u->%u)\n",
1573                              tmpmle->master, tmpmle->new_master);
1574                         /* real master can respond on its own */
1575                         response = DLM_MASTER_RESP_NO;
1576                 } else
1577                         response = DLM_MASTER_RESP_MAYBE;
1578                 if (set_maybe)
1579                         set_bit(request->node_idx, tmpmle->maybe_map);
1580                 spin_unlock(&tmpmle->spinlock);
1581         }
1582         spin_unlock(&dlm->master_lock);
1583         spin_unlock(&dlm->spinlock);
1584
1585         if (found) {
1586                 /* keep the mle attached to heartbeat events */
1587                 dlm_put_mle(tmpmle);
1588         }
1589 send_response:
1590         /*
1591          * __dlm_lookup_lockres() grabbed a reference to this lockres.
1592          * The reference is released by dlm_assert_master_worker() under
1593          * the call to dlm_dispatch_assert_master().  If
1594          * dlm_assert_master_worker() isn't called, we drop it here.
1595          */
1596         if (dispatch_assert) {
1597                 if (response != DLM_MASTER_RESP_YES)
1598                         mlog(ML_ERROR, "invalid response %d\n", response);
1599                 if (!res) {
1600                         mlog(ML_ERROR, "bad lockres while trying to assert!\n");
1601                         BUG();
1602                 }
1603                 mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
1604                              dlm->node_num, res->lockname.len, res->lockname.name);
1605                 ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx,
1606                                                  DLM_ASSERT_MASTER_MLE_CLEANUP);
1607                 if (ret < 0) {
1608                         mlog(ML_ERROR, "failed to dispatch assert master work\n");
1609                         response = DLM_MASTER_RESP_ERROR;
1610                         dlm_lockres_put(res);
1611                 }
1612         } else {
1613                 if (res)
1614                         dlm_lockres_put(res);
1615         }
1616
1617         dlm_put(dlm);
1618         return response;
1619 }
1620
1621 /*
1622  * DLM_ASSERT_MASTER_MSG
1623  */
1624
1625
1626 /*
1627  * NOTE: this can be used for debugging
1628  * can periodically run all locks owned by this node
1629  * and re-assert across the cluster...
1630  */
1631 static int dlm_do_assert_master(struct dlm_ctxt *dlm,
1632                                 struct dlm_lock_resource *res,
1633                                 void *nodemap, u32 flags)
1634 {
1635         struct dlm_assert_master assert;
1636         int to, tmpret;
1637         struct dlm_node_iter iter;
1638         int ret = 0;
1639         int reassert;
1640         const char *lockname = res->lockname.name;
1641         unsigned int namelen = res->lockname.len;
1642
1643         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
1644
1645         spin_lock(&res->spinlock);
1646         res->state |= DLM_LOCK_RES_SETREF_INPROG;
1647         spin_unlock(&res->spinlock);
1648
1649 again:
1650         reassert = 0;
1651
1652         /* note that if this nodemap is empty, it returns 0 */
1653         dlm_node_iter_init(nodemap, &iter);
1654         while ((to = dlm_node_iter_next(&iter)) >= 0) {
1655                 int r = 0;
1656                 struct dlm_master_list_entry *mle = NULL;
1657
1658                 mlog(0, "sending assert master to %d (%.*s)\n", to,
1659                      namelen, lockname);
1660                 memset(&assert, 0, sizeof(assert));
1661                 assert.node_idx = dlm->node_num;
1662                 assert.namelen = namelen;
1663                 memcpy(assert.name, lockname, namelen);
1664                 assert.flags = cpu_to_be32(flags);
1665
1666                 tmpret = o2net_send_message(DLM_ASSERT_MASTER_MSG, dlm->key,
1667                                             &assert, sizeof(assert), to, &r);
1668                 if (tmpret < 0) {
1669                         mlog(0, "assert_master returned %d!\n", tmpret);
1670                         if (!dlm_is_host_down(tmpret)) {
1671                                 mlog(ML_ERROR, "unhandled error=%d!\n", tmpret);
1672                                 BUG();
1673                         }
1674                         /* a node died.  finish out the rest of the nodes. */
1675                         mlog(0, "link to %d went down!\n", to);
1676                         /* any nonzero status return will do */
1677                         ret = tmpret;
1678                         r = 0;
1679                 } else if (r < 0) {
1680                         /* ok, something horribly messed.  kill thyself. */
1681                         mlog(ML_ERROR,"during assert master of %.*s to %u, "
1682                              "got %d.\n", namelen, lockname, to, r);
1683                         spin_lock(&dlm->spinlock);
1684                         spin_lock(&dlm->master_lock);
1685                         if (dlm_find_mle(dlm, &mle, (char *)lockname,
1686                                          namelen)) {
1687                                 dlm_print_one_mle(mle);
1688                                 __dlm_put_mle(mle);
1689                         }
1690                         spin_unlock(&dlm->master_lock);
1691                         spin_unlock(&dlm->spinlock);
1692                         BUG();
1693                 }
1694
1695                 if (r & DLM_ASSERT_RESPONSE_REASSERT &&
1696                     !(r & DLM_ASSERT_RESPONSE_MASTERY_REF)) {
1697                                 mlog(ML_ERROR, "%.*s: very strange, "
1698                                      "master MLE but no lockres on %u\n",
1699                                      namelen, lockname, to);
1700                 }
1701
1702                 if (r & DLM_ASSERT_RESPONSE_REASSERT) {
1703                         mlog(0, "%.*s: node %u create mles on other "
1704                              "nodes and requests a re-assert\n",
1705                              namelen, lockname, to);
1706                         reassert = 1;
1707                 }
1708                 if (r & DLM_ASSERT_RESPONSE_MASTERY_REF) {
1709                         mlog(0, "%.*s: node %u has a reference to this "
1710                              "lockres, set the bit in the refmap\n",
1711                              namelen, lockname, to);
1712                         spin_lock(&res->spinlock);
1713                         dlm_lockres_set_refmap_bit(to, res);
1714                         spin_unlock(&res->spinlock);
1715                 }
1716         }
1717
1718         if (reassert)
1719                 goto again;
1720
1721         spin_lock(&res->spinlock);
1722         res->state &= ~DLM_LOCK_RES_SETREF_INPROG;
1723         spin_unlock(&res->spinlock);
1724         wake_up(&res->wq);
1725
1726         return ret;
1727 }
1728
1729 /*
1730  * locks that can be taken here:
1731  * dlm->spinlock
1732  * res->spinlock
1733  * mle->spinlock
1734  * dlm->master_list
1735  *
1736  * if possible, TRIM THIS DOWN!!!
1737  */
1738 int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data,
1739                               void **ret_data)
1740 {
1741         struct dlm_ctxt *dlm = data;
1742         struct dlm_master_list_entry *mle = NULL;
1743         struct dlm_assert_master *assert = (struct dlm_assert_master *)msg->buf;
1744         struct dlm_lock_resource *res = NULL;
1745         char *name;
1746         unsigned int namelen, hash;
1747         u32 flags;
1748         int master_request = 0, have_lockres_ref = 0;
1749         int ret = 0;
1750
1751         if (!dlm_grab(dlm))
1752                 return 0;
1753
1754         name = assert->name;
1755         namelen = assert->namelen;
1756         hash = dlm_lockid_hash(name, namelen);
1757         flags = be32_to_cpu(assert->flags);
1758
1759         if (namelen > DLM_LOCKID_NAME_MAX) {
1760                 mlog(ML_ERROR, "Invalid name length!");
1761                 goto done;
1762         }
1763
1764         spin_lock(&dlm->spinlock);
1765
1766         if (flags)
1767                 mlog(0, "assert_master with flags: %u\n", flags);
1768
1769         /* find the MLE */
1770         spin_lock(&dlm->master_lock);
1771         if (!dlm_find_mle(dlm, &mle, name, namelen)) {
1772                 /* not an error, could be master just re-asserting */
1773                 mlog(0, "just got an assert_master from %u, but no "
1774                      "MLE for it! (%.*s)\n", assert->node_idx,
1775                      namelen, name);
1776         } else {
1777                 int bit = find_next_bit (mle->maybe_map, O2NM_MAX_NODES, 0);
1778                 if (bit >= O2NM_MAX_NODES) {
1779                         /* not necessarily an error, though less likely.
1780                          * could be master just re-asserting. */
1781                         mlog(0, "no bits set in the maybe_map, but %u "
1782                              "is asserting! (%.*s)\n", assert->node_idx,
1783                              namelen, name);
1784                 } else if (bit != assert->node_idx) {
1785                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1786                                 mlog(0, "master %u was found, %u should "
1787                                      "back off\n", assert->node_idx, bit);
1788                         } else {
1789                                 /* with the fix for bug 569, a higher node
1790                                  * number winning the mastery will respond
1791                                  * YES to mastery requests, but this node
1792                                  * had no way of knowing.  let it pass. */
1793                                 mlog(0, "%u is the lowest node, "
1794                                      "%u is asserting. (%.*s)  %u must "
1795                                      "have begun after %u won.\n", bit,
1796                                      assert->node_idx, namelen, name, bit,
1797                                      assert->node_idx);
1798                         }
1799                 }
1800                 if (mle->type == DLM_MLE_MIGRATION) {
1801                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1802                                 mlog(0, "%s:%.*s: got cleanup assert"
1803                                      " from %u for migration\n",
1804                                      dlm->name, namelen, name,
1805                                      assert->node_idx);
1806                         } else if (!(flags & DLM_ASSERT_MASTER_FINISH_MIGRATION)) {
1807                                 mlog(0, "%s:%.*s: got unrelated assert"
1808                                      " from %u for migration, ignoring\n",
1809                                      dlm->name, namelen, name,
1810                                      assert->node_idx);
1811                                 __dlm_put_mle(mle);
1812                                 spin_unlock(&dlm->master_lock);
1813                                 spin_unlock(&dlm->spinlock);
1814                                 goto done;
1815                         }
1816                 }
1817         }
1818         spin_unlock(&dlm->master_lock);
1819
1820         /* ok everything checks out with the MLE
1821          * now check to see if there is a lockres */
1822         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
1823         if (res) {
1824                 spin_lock(&res->spinlock);
1825                 if (res->state & DLM_LOCK_RES_RECOVERING)  {
1826                         mlog(ML_ERROR, "%u asserting but %.*s is "
1827                              "RECOVERING!\n", assert->node_idx, namelen, name);
1828                         goto kill;
1829                 }
1830                 if (!mle) {
1831                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN &&
1832                             res->owner != assert->node_idx) {
1833                                 mlog(ML_ERROR, "DIE! Mastery assert from %u, "
1834                                      "but current owner is %u! (%.*s)\n",
1835                                      assert->node_idx, res->owner, namelen,
1836                                      name);
1837                                 __dlm_print_one_lock_resource(res);
1838                                 BUG();
1839                         }
1840                 } else if (mle->type != DLM_MLE_MIGRATION) {
1841                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1842                                 /* owner is just re-asserting */
1843                                 if (res->owner == assert->node_idx) {
1844                                         mlog(0, "owner %u re-asserting on "
1845                                              "lock %.*s\n", assert->node_idx,
1846                                              namelen, name);
1847                                         goto ok;
1848                                 }
1849                                 mlog(ML_ERROR, "got assert_master from "
1850                                      "node %u, but %u is the owner! "
1851                                      "(%.*s)\n", assert->node_idx,
1852                                      res->owner, namelen, name);
1853                                 goto kill;
1854                         }
1855                         if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1856                                 mlog(ML_ERROR, "got assert from %u, but lock "
1857                                      "with no owner should be "
1858                                      "in-progress! (%.*s)\n",
1859                                      assert->node_idx,
1860                                      namelen, name);
1861                                 goto kill;
1862                         }
1863                 } else /* mle->type == DLM_MLE_MIGRATION */ {
1864                         /* should only be getting an assert from new master */
1865                         if (assert->node_idx != mle->new_master) {
1866                                 mlog(ML_ERROR, "got assert from %u, but "
1867                                      "new master is %u, and old master "
1868                                      "was %u (%.*s)\n",
1869                                      assert->node_idx, mle->new_master,
1870                                      mle->master, namelen, name);
1871                                 goto kill;
1872                         }
1873
1874                 }
1875 ok:
1876                 spin_unlock(&res->spinlock);
1877         }
1878         spin_unlock(&dlm->spinlock);
1879
1880         // mlog(0, "woo!  got an assert_master from node %u!\n",
1881         //           assert->node_idx);
1882         if (mle) {
1883                 int extra_ref = 0;
1884                 int nn = -1;
1885                 int rr, err = 0;
1886
1887                 spin_lock(&mle->spinlock);
1888                 if (mle->type == DLM_MLE_BLOCK || mle->type == DLM_MLE_MIGRATION)
1889                         extra_ref = 1;
1890                 else {
1891                         /* MASTER mle: if any bits set in the response map
1892                          * then the calling node needs to re-assert to clear
1893                          * up nodes that this node contacted */
1894                         while ((nn = find_next_bit (mle->response_map, O2NM_MAX_NODES,
1895                                                     nn+1)) < O2NM_MAX_NODES) {
1896                                 if (nn != dlm->node_num && nn != assert->node_idx)
1897                                         master_request = 1;
1898                         }
1899                 }
1900                 mle->master = assert->node_idx;
1901                 atomic_set(&mle->woken, 1);
1902                 wake_up(&mle->wq);
1903                 spin_unlock(&mle->spinlock);
1904
1905                 if (res) {
1906                         int wake = 0;
1907                         spin_lock(&res->spinlock);
1908                         if (mle->type == DLM_MLE_MIGRATION) {
1909                                 mlog(0, "finishing off migration of lockres %.*s, "
1910                                         "from %u to %u\n",
1911                                         res->lockname.len, res->lockname.name,
1912                                         dlm->node_num, mle->new_master);
1913                                 res->state &= ~DLM_LOCK_RES_MIGRATING;
1914                                 wake = 1;
1915                                 dlm_change_lockres_owner(dlm, res, mle->new_master);
1916                                 BUG_ON(res->state & DLM_LOCK_RES_DIRTY);
1917                         } else {
1918                                 dlm_change_lockres_owner(dlm, res, mle->master);
1919                         }
1920                         spin_unlock(&res->spinlock);
1921                         have_lockres_ref = 1;
1922                         if (wake)
1923                                 wake_up(&res->wq);
1924                 }
1925
1926                 /* master is known, detach if not already detached.
1927                  * ensures that only one assert_master call will happen
1928                  * on this mle. */
1929                 spin_lock(&dlm->spinlock);
1930                 spin_lock(&dlm->master_lock);
1931
1932                 rr = atomic_read(&mle->mle_refs.refcount);
1933                 if (mle->inuse > 0) {
1934                         if (extra_ref && rr < 3)
1935                                 err = 1;
1936                         else if (!extra_ref && rr < 2)
1937                                 err = 1;
1938                 } else {
1939                         if (extra_ref && rr < 2)
1940                                 err = 1;
1941                         else if (!extra_ref && rr < 1)
1942                                 err = 1;
1943                 }
1944                 if (err) {
1945                         mlog(ML_ERROR, "%s:%.*s: got assert master from %u "
1946                              "that will mess up this node, refs=%d, extra=%d, "
1947                              "inuse=%d\n", dlm->name, namelen, name,
1948                              assert->node_idx, rr, extra_ref, mle->inuse);
1949                         dlm_print_one_mle(mle);
1950                 }
1951                 __dlm_unlink_mle(dlm, mle);
1952                 __dlm_mle_detach_hb_events(dlm, mle);
1953                 __dlm_put_mle(mle);
1954                 if (extra_ref) {
1955                         /* the assert master message now balances the extra
1956                          * ref given by the master / migration request message.
1957                          * if this is the last put, it will be removed
1958                          * from the list. */
1959                         __dlm_put_mle(mle);
1960                 }
1961                 spin_unlock(&dlm->master_lock);
1962                 spin_unlock(&dlm->spinlock);
1963         } else if (res) {
1964                 if (res->owner != assert->node_idx) {
1965                         mlog(0, "assert_master from %u, but current "
1966                              "owner is %u (%.*s), no mle\n", assert->node_idx,
1967                              res->owner, namelen, name);
1968                 }
1969         }
1970
1971 done:
1972         ret = 0;
1973         if (res) {
1974                 spin_lock(&res->spinlock);
1975                 res->state |= DLM_LOCK_RES_SETREF_INPROG;
1976                 spin_unlock(&res->spinlock);
1977                 *ret_data = (void *)res;
1978         }
1979         dlm_put(dlm);
1980         if (master_request) {
1981                 mlog(0, "need to tell master to reassert\n");
1982                 /* positive. negative would shoot down the node. */
1983                 ret |= DLM_ASSERT_RESPONSE_REASSERT;
1984                 if (!have_lockres_ref) {
1985                         mlog(ML_ERROR, "strange, got assert from %u, MASTER "
1986                              "mle present here for %s:%.*s, but no lockres!\n",
1987                              assert->node_idx, dlm->name, namelen, name);
1988                 }
1989         }
1990         if (have_lockres_ref) {
1991                 /* let the master know we have a reference to the lockres */
1992                 ret |= DLM_ASSERT_RESPONSE_MASTERY_REF;
1993                 mlog(0, "%s:%.*s: got assert from %u, need a ref\n",
1994                      dlm->name, namelen, name, assert->node_idx);
1995         }
1996         return ret;
1997
1998 kill:
1999         /* kill the caller! */
2000         mlog(ML_ERROR, "Bad message received from another node.  Dumping state "
2001              "and killing the other node now!  This node is OK and can continue.\n");
2002         __dlm_print_one_lock_resource(res);
2003         spin_unlock(&res->spinlock);
2004         spin_unlock(&dlm->spinlock);
2005         *ret_data = (void *)res;
2006         dlm_put(dlm);
2007         return -EINVAL;
2008 }
2009
2010 void dlm_assert_master_post_handler(int status, void *data, void *ret_data)
2011 {
2012         struct dlm_lock_resource *res = (struct dlm_lock_resource *)ret_data;
2013
2014         if (ret_data) {
2015                 spin_lock(&res->spinlock);
2016                 res->state &= ~DLM_LOCK_RES_SETREF_INPROG;
2017                 spin_unlock(&res->spinlock);
2018                 wake_up(&res->wq);
2019                 dlm_lockres_put(res);
2020         }
2021         return;
2022 }
2023
2024 int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
2025                                struct dlm_lock_resource *res,
2026                                int ignore_higher, u8 request_from, u32 flags)
2027 {
2028         struct dlm_work_item *item;
2029         item = kzalloc(sizeof(*item), GFP_NOFS);
2030         if (!item)
2031                 return -ENOMEM;
2032
2033
2034         /* queue up work for dlm_assert_master_worker */
2035         dlm_grab(dlm);  /* get an extra ref for the work item */
2036         dlm_init_work_item(dlm, item, dlm_assert_master_worker, NULL);
2037         item->u.am.lockres = res; /* already have a ref */
2038         /* can optionally ignore node numbers higher than this node */
2039         item->u.am.ignore_higher = ignore_higher;
2040         item->u.am.request_from = request_from;
2041         item->u.am.flags = flags;
2042
2043         if (ignore_higher)
2044                 mlog(0, "IGNORE HIGHER: %.*s\n", res->lockname.len,
2045                      res->lockname.name);
2046
2047         spin_lock(&dlm->work_lock);
2048         list_add_tail(&item->list, &dlm->work_list);
2049         spin_unlock(&dlm->work_lock);
2050
2051         queue_work(dlm->dlm_worker, &dlm->dispatched_work);
2052         return 0;
2053 }
2054
2055 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
2056 {
2057         struct dlm_ctxt *dlm = data;
2058         int ret = 0;
2059         struct dlm_lock_resource *res;
2060         unsigned long nodemap[BITS_TO_LONGS(O2NM_MAX_NODES)];
2061         int ignore_higher;
2062         int bit;
2063         u8 request_from;
2064         u32 flags;
2065
2066         dlm = item->dlm;
2067         res = item->u.am.lockres;
2068         ignore_higher = item->u.am.ignore_higher;
2069         request_from = item->u.am.request_from;
2070         flags = item->u.am.flags;
2071
2072         spin_lock(&dlm->spinlock);
2073         memcpy(nodemap, dlm->domain_map, sizeof(nodemap));
2074         spin_unlock(&dlm->spinlock);
2075
2076         clear_bit(dlm->node_num, nodemap);
2077         if (ignore_higher) {
2078                 /* if is this just to clear up mles for nodes below
2079                  * this node, do not send the message to the original
2080                  * caller or any node number higher than this */
2081                 clear_bit(request_from, nodemap);
2082                 bit = dlm->node_num;
2083                 while (1) {
2084                         bit = find_next_bit(nodemap, O2NM_MAX_NODES,
2085                                             bit+1);
2086                         if (bit >= O2NM_MAX_NODES)
2087                                 break;
2088                         clear_bit(bit, nodemap);
2089                 }
2090         }
2091
2092         /*
2093          * If we're migrating this lock to someone else, we are no
2094          * longer allowed to assert out own mastery.  OTOH, we need to
2095          * prevent migration from starting while we're still asserting
2096          * our dominance.  The reserved ast delays migration.
2097          */
2098         spin_lock(&res->spinlock);
2099         if (res->state & DLM_LOCK_RES_MIGRATING) {
2100                 mlog(0, "Someone asked us to assert mastery, but we're "
2101                      "in the middle of migration.  Skipping assert, "
2102                      "the new master will handle that.\n");
2103                 spin_unlock(&res->spinlock);
2104                 goto put;
2105         } else
2106                 __dlm_lockres_reserve_ast(res);
2107         spin_unlock(&res->spinlock);
2108
2109         /* this call now finishes out the nodemap
2110          * even if one or more nodes die */
2111         mlog(0, "worker about to master %.*s here, this=%u\n",
2112                      res->lockname.len, res->lockname.name, dlm->node_num);
2113         ret = dlm_do_assert_master(dlm, res, nodemap, flags);
2114         if (ret < 0) {
2115                 /* no need to restart, we are done */
2116                 if (!dlm_is_host_down(ret))
2117                         mlog_errno(ret);
2118         }
2119
2120         /* Ok, we've asserted ourselves.  Let's let migration start. */
2121         dlm_lockres_release_ast(dlm, res);
2122
2123 put:
2124         dlm_lockres_put(res);
2125
2126         mlog(0, "finished with dlm_assert_master_worker\n");
2127 }
2128
2129 /* SPECIAL CASE for the $RECOVERY lock used by the recovery thread.
2130  * We cannot wait for node recovery to complete to begin mastering this
2131  * lockres because this lockres is used to kick off recovery! ;-)
2132  * So, do a pre-check on all living nodes to see if any of those nodes
2133  * think that $RECOVERY is currently mastered by a dead node.  If so,
2134  * we wait a short time to allow that node to get notified by its own
2135  * heartbeat stack, then check again.  All $RECOVERY lock resources
2136  * mastered by dead nodes are purged when the hearbeat callback is
2137  * fired, so we can know for sure that it is safe to continue once
2138  * the node returns a live node or no node.  */
2139 static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
2140                                        struct dlm_lock_resource *res)
2141 {
2142         struct dlm_node_iter iter;
2143         int nodenum;
2144         int ret = 0;
2145         u8 master = DLM_LOCK_RES_OWNER_UNKNOWN;
2146
2147         spin_lock(&dlm->spinlock);
2148         dlm_node_iter_init(dlm->domain_map, &iter);
2149         spin_unlock(&dlm->spinlock);
2150
2151         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
2152                 /* do not send to self */
2153                 if (nodenum == dlm->node_num)
2154                         continue;
2155                 ret = dlm_do_master_requery(dlm, res, nodenum, &master);
2156                 if (ret < 0) {
2157                         mlog_errno(ret);
2158                         if (!dlm_is_host_down(ret))
2159                                 BUG();
2160                         /* host is down, so answer for that node would be
2161                          * DLM_LOCK_RES_OWNER_UNKNOWN.  continue. */
2162                         ret = 0;
2163                 }
2164
2165                 if (master != DLM_LOCK_RES_OWNER_UNKNOWN) {
2166                         /* check to see if this master is in the recovery map */
2167                         spin_lock(&dlm->spinlock);
2168                         if (test_bit(master, dlm->recovery_map)) {
2169                                 mlog(ML_NOTICE, "%s: node %u has not seen "
2170                                      "node %u go down yet, and thinks the "
2171                                      "dead node is mastering the recovery "
2172                                      "lock.  must wait.\n", dlm->name,
2173                                      nodenum, master);
2174                                 ret = -EAGAIN;
2175                         }
2176                         spin_unlock(&dlm->spinlock);
2177                         mlog(0, "%s: reco lock master is %u\n", dlm->name,
2178                              master);
2179                         break;
2180                 }
2181         }
2182         return ret;
2183 }
2184
2185 /*
2186  * DLM_DEREF_LOCKRES_MSG
2187  */
2188
2189 int dlm_drop_lockres_ref(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
2190 {
2191         struct dlm_deref_lockres deref;
2192         int ret = 0, r;
2193         const char *lockname;
2194         unsigned int namelen;
2195
2196         lockname = res->lockname.name;
2197         namelen = res->lockname.len;
2198         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
2199
2200         mlog(0, "%s:%.*s: sending deref to %d\n",
2201              dlm->name, namelen, lockname, res->owner);
2202         memset(&deref, 0, sizeof(deref));
2203         deref.node_idx = dlm->node_num;
2204         deref.namelen = namelen;
2205         memcpy(deref.name, lockname, namelen);
2206
2207         ret = o2net_send_message(DLM_DEREF_LOCKRES_MSG, dlm->key,
2208                                  &deref, sizeof(deref), res->owner, &r);
2209         if (ret < 0)
2210                 mlog_errno(ret);
2211         else if (r < 0) {
2212                 /* BAD.  other node says I did not have a ref. */
2213                 mlog(ML_ERROR,"while dropping ref on %s:%.*s "
2214                     "(master=%u) got %d.\n", dlm->name, namelen,
2215                     lockname, res->owner, r);
2216                 dlm_print_one_lock_resource(res);
2217                 BUG();
2218         }
2219         return ret;
2220 }
2221
2222 int dlm_deref_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
2223                               void **ret_data)
2224 {
2225         struct dlm_ctxt *dlm = data;
2226         struct dlm_deref_lockres *deref = (struct dlm_deref_lockres *)msg->buf;
2227         struct dlm_lock_resource *res = NULL;
2228         char *name;
2229         unsigned int namelen;
2230         int ret = -EINVAL;
2231         u8 node;
2232         unsigned int hash;
2233         struct dlm_work_item *item;
2234         int cleared = 0;
2235         int dispatch = 0;
2236
2237         if (!dlm_grab(dlm))
2238                 return 0;
2239
2240         name = deref->name;
2241         namelen = deref->namelen;
2242         node = deref->node_idx;
2243
2244         if (namelen > DLM_LOCKID_NAME_MAX) {
2245                 mlog(ML_ERROR, "Invalid name length!");
2246                 goto done;
2247         }
2248         if (deref->node_idx >= O2NM_MAX_NODES) {
2249                 mlog(ML_ERROR, "Invalid node number: %u\n", node);
2250                 goto done;
2251         }
2252
2253         hash = dlm_lockid_hash(name, namelen);
2254
2255         spin_lock(&dlm->spinlock);
2256         res = __dlm_lookup_lockres_full(dlm, name, namelen, hash);
2257         if (!res) {
2258                 spin_unlock(&dlm->spinlock);
2259                 mlog(ML_ERROR, "%s:%.*s: bad lockres name\n",
2260                      dlm->name, namelen, name);
2261                 goto done;
2262         }
2263         spin_unlock(&dlm->spinlock);
2264
2265         spin_lock(&res->spinlock);
2266         if (res->state & DLM_LOCK_RES_SETREF_INPROG)
2267                 dispatch = 1;
2268         else {
2269                 BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
2270                 if (test_bit(node, res->refmap)) {
2271                         dlm_lockres_clear_refmap_bit(node, res);
2272                         cleared = 1;
2273                 }
2274         }
2275         spin_unlock(&res->spinlock);
2276
2277         if (!dispatch) {
2278                 if (cleared)
2279                         dlm_lockres_calc_usage(dlm, res);
2280                 else {
2281                         mlog(ML_ERROR, "%s:%.*s: node %u trying to drop ref "
2282                         "but it is already dropped!\n", dlm->name,
2283                         res->lockname.len, res->lockname.name, node);
2284                         dlm_print_one_lock_resource(res);
2285                 }
2286                 ret = 0;
2287                 goto done;
2288         }
2289
2290         item = kzalloc(sizeof(*item), GFP_NOFS);
2291         if (!item) {
2292                 ret = -ENOMEM;
2293                 mlog_errno(ret);
2294                 goto done;
2295         }
2296
2297         dlm_init_work_item(dlm, item, dlm_deref_lockres_worker, NULL);
2298         item->u.dl.deref_res = res;
2299         item->u.dl.deref_node = node;
2300
2301         spin_lock(&dlm->work_lock);
2302         list_add_tail(&item->list, &dlm->work_list);
2303         spin_unlock(&dlm->work_lock);
2304
2305         queue_work(dlm->dlm_worker, &dlm->dispatched_work);
2306         return 0;
2307
2308 done:
2309         if (res)
2310                 dlm_lockres_put(res);
2311         dlm_put(dlm);
2312
2313         return ret;
2314 }
2315
2316 static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data)
2317 {
2318         struct dlm_ctxt *dlm;
2319         struct dlm_lock_resource *res;
2320         u8 node;
2321         u8 cleared = 0;
2322
2323         dlm = item->dlm;
2324         res = item->u.dl.deref_res;
2325         node = item->u.dl.deref_node;
2326
2327         spin_lock(&res->spinlock);
2328         BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
2329         if (test_bit(node, res->refmap)) {
2330                 __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
2331                 dlm_lockres_clear_refmap_bit(node, res);
2332                 cleared = 1;
2333         }
2334         spin_unlock(&res->spinlock);
2335
2336         if (cleared) {
2337                 mlog(0, "%s:%.*s node %u ref dropped in dispatch\n",
2338                      dlm->name, res->lockname.len, res->lockname.name, node);
2339                 dlm_lockres_calc_usage(dlm, res);
2340         } else {
2341                 mlog(ML_ERROR, "%s:%.*s: node %u trying to drop ref "
2342                      "but it is already dropped!\n", dlm->name,
2343                      res->lockname.len, res->lockname.name, node);
2344                 dlm_print_one_lock_resource(res);
2345         }
2346
2347         dlm_lockres_put(res);
2348 }
2349
2350 /* Checks whether the lockres can be migrated. Returns 0 if yes, < 0
2351  * if not. If 0, numlocks is set to the number of locks in the lockres.
2352  */
2353 static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm,
2354                                       struct dlm_lock_resource *res,
2355                                       int *numlocks)
2356 {
2357         int ret;
2358         int i;
2359         int count = 0;
2360         struct list_head *queue;
2361         struct dlm_lock *lock;
2362
2363         assert_spin_locked(&res->spinlock);
2364
2365         ret = -EINVAL;
2366         if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
2367                 mlog(0, "cannot migrate lockres with unknown owner!\n");
2368                 goto leave;
2369         }
2370
2371         if (res->owner != dlm->node_num) {
2372                 mlog(0, "cannot migrate lockres this node doesn't own!\n");
2373                 goto leave;
2374         }
2375
2376         ret = 0;
2377         queue = &res->granted;
2378         for (i = 0; i < 3; i++) {
2379                 list_for_each_entry(lock, queue, list) {
2380                         ++count;
2381                         if (lock->ml.node == dlm->node_num) {
2382                                 mlog(0, "found a lock owned by this node still "
2383                                      "on the %s queue!  will not migrate this "
2384                                      "lockres\n", (i == 0 ? "granted" :
2385                                                    (i == 1 ? "converting" :
2386                                                     "blocked")));
2387                                 ret = -ENOTEMPTY;
2388                                 goto leave;
2389                         }
2390                 }
2391                 queue++;
2392         }
2393
2394         *numlocks = count;
2395         mlog(0, "migrateable lockres having %d locks\n", *numlocks);
2396
2397 leave:
2398         return ret;
2399 }
2400
2401 /*
2402  * DLM_MIGRATE_LOCKRES
2403  */
2404
2405
2406 static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
2407                                struct dlm_lock_resource *res,
2408                                u8 target)
2409 {
2410         struct dlm_master_list_entry *mle = NULL;
2411         struct dlm_master_list_entry *oldmle = NULL;
2412         struct dlm_migratable_lockres *mres = NULL;
2413         int ret = 0;
2414         const char *name;
2415         unsigned int namelen;
2416         int mle_added = 0;
2417         int numlocks;
2418         int wake = 0;
2419
2420         if (!dlm_grab(dlm))
2421                 return -EINVAL;
2422
2423         name = res->lockname.name;
2424         namelen = res->lockname.len;
2425
2426         mlog(0, "migrating %.*s to %u\n", namelen, name, target);
2427
2428         /*
2429          * ensure this lockres is a proper candidate for migration
2430          */
2431         spin_lock(&res->spinlock);
2432         ret = dlm_is_lockres_migrateable(dlm, res, &numlocks);
2433         if (ret < 0) {
2434                 spin_unlock(&res->spinlock);
2435                 goto leave;
2436         }
2437         spin_unlock(&res->spinlock);
2438
2439         /* no work to do */
2440         if (numlocks == 0) {
2441                 mlog(0, "no locks were found on this lockres! done!\n");
2442                 goto leave;
2443         }
2444
2445         /*
2446          * preallocate up front
2447          * if this fails, abort
2448          */
2449
2450         ret = -ENOMEM;
2451         mres = (struct dlm_migratable_lockres *) __get_free_page(GFP_NOFS);
2452         if (!mres) {
2453                 mlog_errno(ret);
2454                 goto leave;
2455         }
2456
2457         mle = (struct dlm_master_list_entry *) kmem_cache_alloc(dlm_mle_cache,
2458                                                                 GFP_NOFS);
2459         if (!mle) {
2460                 mlog_errno(ret);
2461                 goto leave;
2462         }
2463         ret = 0;
2464
2465         /*
2466          * find a node to migrate the lockres to
2467          */
2468
2469         mlog(0, "picking a migration node\n");
2470         spin_lock(&dlm->spinlock);
2471         /* pick a new node */
2472         if (!test_bit(target, dlm->domain_map) ||
2473             target >= O2NM_MAX_NODES) {
2474                 target = dlm_pick_migration_target(dlm, res);
2475         }
2476         mlog(0, "node %u chosen for migration\n", target);
2477
2478         if (target >= O2NM_MAX_NODES ||
2479             !test_bit(target, dlm->domain_map)) {
2480                 /* target chosen is not alive */
2481                 ret = -EINVAL;
2482         }
2483
2484         if (ret) {
2485                 spin_unlock(&dlm->spinlock);
2486                 goto fail;
2487         }
2488
2489         mlog(0, "continuing with target = %u\n", target);
2490
2491         /*
2492          * clear any existing master requests and
2493          * add the migration mle to the list
2494          */
2495         spin_lock(&dlm->master_lock);
2496         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
2497                                     namelen, target, dlm->node_num);
2498         spin_unlock(&dlm->master_lock);
2499         spin_unlock(&dlm->spinlock);
2500
2501         if (ret == -EEXIST) {
2502                 mlog(0, "another process is already migrating it\n");
2503                 goto fail;
2504         }
2505         mle_added = 1;
2506
2507         /*
2508          * set the MIGRATING flag and flush asts
2509          * if we fail after this we need to re-dirty the lockres
2510          */
2511         if (dlm_mark_lockres_migrating(dlm, res, target) < 0) {
2512                 mlog(ML_ERROR, "tried to migrate %.*s to %u, but "
2513                      "the target went down.\n", res->lockname.len,
2514                      res->lockname.name, target);
2515                 spin_lock(&res->spinlock);
2516                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2517                 wake = 1;
2518                 spin_unlock(&res->spinlock);
2519                 ret = -EINVAL;
2520         }
2521
2522 fail:
2523         if (oldmle) {
2524                 /* master is known, detach if not already detached */
2525                 dlm_mle_detach_hb_events(dlm, oldmle);
2526                 dlm_put_mle(oldmle);
2527         }
2528
2529         if (ret < 0) {
2530                 if (mle_added) {
2531                         dlm_mle_detach_hb_events(dlm, mle);
2532                         dlm_put_mle(mle);
2533                 } else if (mle) {
2534                         kmem_cache_free(dlm_mle_cache, mle);
2535                 }
2536                 goto leave;
2537         }
2538
2539         /*
2540          * at this point, we have a migration target, an mle
2541          * in the master list, and the MIGRATING flag set on
2542          * the lockres
2543          */
2544
2545         /* now that remote nodes are spinning on the MIGRATING flag,
2546          * ensure that all assert_master work is flushed. */
2547         flush_workqueue(dlm->dlm_worker);
2548
2549         /* get an extra reference on the mle.
2550          * otherwise the assert_master from the new
2551          * master will destroy this.
2552          * also, make sure that all callers of dlm_get_mle
2553          * take both dlm->spinlock and dlm->master_lock */
2554         spin_lock(&dlm->spinlock);
2555         spin_lock(&dlm->master_lock);
2556         dlm_get_mle_inuse(mle);
2557         spin_unlock(&dlm->master_lock);
2558         spin_unlock(&dlm->spinlock);
2559
2560         /* notify new node and send all lock state */
2561         /* call send_one_lockres with migration flag.
2562          * this serves as notice to the target node that a
2563          * migration is starting. */
2564         ret = dlm_send_one_lockres(dlm, res, mres, target,
2565                                    DLM_MRES_MIGRATION);
2566
2567         if (ret < 0) {
2568                 mlog(0, "migration to node %u failed with %d\n",
2569                      target, ret);
2570                 /* migration failed, detach and clean up mle */
2571                 dlm_mle_detach_hb_events(dlm, mle);
2572                 dlm_put_mle(mle);
2573                 dlm_put_mle_inuse(mle);
2574                 spin_lock(&res->spinlock);
2575                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2576                 wake = 1;
2577                 spin_unlock(&res->spinlock);
2578                 goto leave;
2579         }
2580
2581         /* at this point, the target sends a message to all nodes,
2582          * (using dlm_do_migrate_request).  this node is skipped since
2583          * we had to put an mle in the list to begin the process.  this
2584          * node now waits for target to do an assert master.  this node
2585          * will be the last one notified, ensuring that the migration
2586          * is complete everywhere.  if the target dies while this is
2587          * going on, some nodes could potentially see the target as the
2588          * master, so it is important that my recovery finds the migration
2589          * mle and sets the master to UNKNOWN. */
2590
2591
2592         /* wait for new node to assert master */
2593         while (1) {
2594                 ret = wait_event_interruptible_timeout(mle->wq,
2595                                         (atomic_read(&mle->woken) == 1),
2596                                         msecs_to_jiffies(5000));
2597
2598                 if (ret >= 0) {
2599                         if (atomic_read(&mle->woken) == 1 ||
2600                             res->owner == target)
2601                                 break;
2602
2603                         mlog(0, "%s:%.*s: timed out during migration\n",
2604                              dlm->name, res->lockname.len, res->lockname.name);
2605                         /* avoid hang during shutdown when migrating lockres
2606                          * to a node which also goes down */
2607                         if (dlm_is_node_dead(dlm, target)) {
2608                                 mlog(0, "%s:%.*s: expected migration "
2609                                      "target %u is no longer up, restarting\n",
2610                                      dlm->name, res->lockname.len,
2611                                      res->lockname.name, target);
2612                                 ret = -EINVAL;
2613                                 /* migration failed, detach and clean up mle */
2614                                 dlm_mle_detach_hb_events(dlm, mle);
2615                                 dlm_put_mle(mle);
2616                                 dlm_put_mle_inuse(mle);
2617                                 spin_lock(&res->spinlock);
2618                                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2619                                 wake = 1;
2620                                 spin_unlock(&res->spinlock);
2621                                 goto leave;
2622                         }
2623                 } else
2624                         mlog(0, "%s:%.*s: caught signal during migration\n",
2625                              dlm->name, res->lockname.len, res->lockname.name);
2626         }
2627
2628         /* all done, set the owner, clear the flag */
2629         spin_lock(&res->spinlock);
2630         dlm_set_lockres_owner(dlm, res, target);
2631         res->state &= ~DLM_LOCK_RES_MIGRATING;
2632         dlm_remove_nonlocal_locks(dlm, res);
2633         spin_unlock(&res->spinlock);
2634         wake_up(&res->wq);
2635
2636         /* master is known, detach if not already detached */
2637         dlm_mle_detach_hb_events(dlm, mle);
2638         dlm_put_mle_inuse(mle);
2639         ret = 0;
2640
2641         dlm_lockres_calc_usage(dlm, res);
2642
2643 leave:
2644         /* re-dirty the lockres if we failed */
2645         if (ret < 0)
2646                 dlm_kick_thread(dlm, res);
2647
2648         /* wake up waiters if the MIGRATING flag got set
2649          * but migration failed */
2650         if (wake)
2651                 wake_up(&res->wq);
2652
2653         /* TODO: cleanup */
2654         if (mres)
2655                 free_page((unsigned long)mres);
2656
2657         dlm_put(dlm);
2658
2659         mlog(0, "returning %d\n", ret);
2660         return ret;
2661 }
2662
2663 #define DLM_MIGRATION_RETRY_MS  100
2664
2665 /* Should be called only after beginning the domain leave process.
2666  * There should not be any remaining locks on nonlocal lock resources,
2667  * and there should be no local locks left on locally mastered resources.
2668  *
2669  * Called with the dlm spinlock held, may drop it to do migration, but
2670  * will re-acquire before exit.
2671  *
2672  * Returns: 1 if dlm->spinlock was dropped/retaken, 0 if never dropped */
2673 int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
2674 {
2675         int ret;
2676         int lock_dropped = 0;
2677         int numlocks;
2678
2679         spin_lock(&res->spinlock);
2680         if (res->owner != dlm->node_num) {
2681                 if (!__dlm_lockres_unused(res)) {
2682                         mlog(ML_ERROR, "%s:%.*s: this node is not master, "
2683                              "trying to free this but locks remain\n",
2684                              dlm->name, res->lockname.len, res->lockname.name);
2685                 }
2686                 spin_unlock(&res->spinlock);
2687                 goto leave;
2688         }
2689
2690         /* No need to migrate a lockres having no locks */
2691         ret = dlm_is_lockres_migrateable(dlm, res, &numlocks);
2692         if (ret >= 0 && numlocks == 0) {
2693                 spin_unlock(&res->spinlock);
2694                 goto leave;
2695         }
2696         spin_unlock(&res->spinlock);
2697
2698         /* Wheee! Migrate lockres here! Will sleep so drop spinlock. */
2699         spin_unlock(&dlm->spinlock);
2700         lock_dropped = 1;
2701         while (1) {
2702                 ret = dlm_migrate_lockres(dlm, res, O2NM_MAX_NODES);
2703                 if (ret >= 0)
2704                         break;
2705                 if (ret == -ENOTEMPTY) {
2706                         mlog(ML_ERROR, "lockres %.*s still has local locks!\n",
2707                                 res->lockname.len, res->lockname.name);
2708                         BUG();
2709                 }
2710
2711                 mlog(0, "lockres %.*s: migrate failed, "
2712                      "retrying\n", res->lockname.len,
2713                      res->lockname.name);
2714                 msleep(DLM_MIGRATION_RETRY_MS);
2715         }
2716         spin_lock(&dlm->spinlock);
2717 leave:
2718         return lock_dropped;
2719 }
2720
2721 int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock)
2722 {
2723         int ret;
2724         spin_lock(&dlm->ast_lock);
2725         spin_lock(&lock->spinlock);
2726         ret = (list_empty(&lock->bast_list) && !lock->bast_pending);
2727         spin_unlock(&lock->spinlock);
2728         spin_unlock(&dlm->ast_lock);
2729         return ret;
2730 }
2731
2732 static int dlm_migration_can_proceed(struct dlm_ctxt *dlm,
2733                                      struct dlm_lock_resource *res,
2734                                      u8 mig_target)
2735 {
2736         int can_proceed;
2737         spin_lock(&res->spinlock);
2738         can_proceed = !!(res->state & DLM_LOCK_RES_MIGRATING);
2739         spin_unlock(&res->spinlock);
2740
2741         /* target has died, so make the caller break out of the
2742          * wait_event, but caller must recheck the domain_map */
2743         spin_lock(&dlm->spinlock);
2744         if (!test_bit(mig_target, dlm->domain_map))
2745                 can_proceed = 1;
2746         spin_unlock(&dlm->spinlock);
2747         return can_proceed;
2748 }
2749
2750 static int dlm_lockres_is_dirty(struct dlm_ctxt *dlm,
2751                                 struct dlm_lock_resource *res)
2752 {
2753         int ret;
2754         spin_lock(&res->spinlock);
2755         ret = !!(res->state & DLM_LOCK_RES_DIRTY);
2756         spin_unlock(&res->spinlock);
2757         return ret;
2758 }
2759
2760
2761 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
2762                                        struct dlm_lock_resource *res,
2763                                        u8 target)
2764 {
2765         int ret = 0;
2766
2767         mlog(0, "dlm_mark_lockres_migrating: %.*s, from %u to %u\n",
2768                res->lockname.len, res->lockname.name, dlm->node_num,
2769                target);
2770         /* need to set MIGRATING flag on lockres.  this is done by
2771          * ensuring that all asts have been flushed for this lockres. */
2772         spin_lock(&res->spinlock);
2773         BUG_ON(res->migration_pending);
2774         res->migration_pending = 1;
2775         /* strategy is to reserve an extra ast then release
2776          * it below, letting the release do all of the work */
2777         __dlm_lockres_reserve_ast(res);
2778         spin_unlock(&res->spinlock);
2779
2780         /* now flush all the pending asts */
2781         dlm_kick_thread(dlm, res);
2782         /* before waiting on DIRTY, block processes which may
2783          * try to dirty the lockres before MIGRATING is set */
2784         spin_lock(&res->spinlock);
2785         BUG_ON(res->state & DLM_LOCK_RES_BLOCK_DIRTY);
2786         res->state |= DLM_LOCK_RES_BLOCK_DIRTY;
2787         spin_unlock(&res->spinlock);
2788         /* now wait on any pending asts and the DIRTY state */
2789         wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
2790         dlm_lockres_release_ast(dlm, res);
2791
2792         mlog(0, "about to wait on migration_wq, dirty=%s\n",
2793                res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
2794         /* if the extra ref we just put was the final one, this
2795          * will pass thru immediately.  otherwise, we need to wait
2796          * for the last ast to finish. */
2797 again:
2798         ret = wait_event_interruptible_timeout(dlm->migration_wq,
2799                    dlm_migration_can_proceed(dlm, res, target),
2800                    msecs_to_jiffies(1000));
2801         if (ret < 0) {
2802                 mlog(0, "woken again: migrating? %s, dead? %s\n",
2803                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2804                        test_bit(target, dlm->domain_map) ? "no":"yes");
2805         } else {
2806                 mlog(0, "all is well: migrating? %s, dead? %s\n",
2807                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2808                        test_bit(target, dlm->domain_map) ? "no":"yes");
2809         }
2810         if (!dlm_migration_can_proceed(dlm, res, target)) {
2811                 mlog(0, "trying again...\n");
2812                 goto again;
2813         }
2814         /* now that we are sure the MIGRATING state is there, drop
2815          * the unneded state which blocked threads trying to DIRTY */
2816         spin_lock(&res->spinlock);
2817         BUG_ON(!(res->state & DLM_LOCK_RES_BLOCK_DIRTY));
2818         BUG_ON(!(res->state & DLM_LOCK_RES_MIGRATING));
2819         res->state &= ~DLM_LOCK_RES_BLOCK_DIRTY;
2820         spin_unlock(&res->spinlock);
2821
2822         /* did the target go down or die? */
2823         spin_lock(&dlm->spinlock);
2824         if (!test_bit(target, dlm->domain_map)) {
2825                 mlog(ML_ERROR, "aha. migration target %u just went down\n",
2826                      target);
2827                 ret = -EHOSTDOWN;
2828         }
2829         spin_unlock(&dlm->spinlock);
2830
2831         /*
2832          * at this point:
2833          *
2834          *   o the DLM_LOCK_RES_MIGRATING flag is set
2835          *   o there are no pending asts on this lockres
2836          *   o all processes trying to reserve an ast on this
2837          *     lockres must wait for the MIGRATING flag to clear
2838          */
2839         return ret;
2840 }
2841
2842 /* last step in the migration process.
2843  * original master calls this to free all of the dlm_lock
2844  * structures that used to be for other nodes. */
2845 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
2846                                       struct dlm_lock_resource *res)
2847 {
2848         struct list_head *queue = &res->granted;
2849         int i, bit;
2850         struct dlm_lock *lock, *next;
2851
2852         assert_spin_locked(&res->spinlock);
2853
2854         BUG_ON(res->owner == dlm->node_num);
2855
2856         for (i=0; i<3; i++) {
2857                 list_for_each_entry_safe(lock, next, queue, list) {
2858                         if (lock->ml.node != dlm->node_num) {
2859                                 mlog(0, "putting lock for node %u\n",
2860                                      lock->ml.node);
2861                                 /* be extra careful */
2862                                 BUG_ON(!list_empty(&lock->ast_list));
2863                                 BUG_ON(!list_empty(&lock->bast_list));
2864                                 BUG_ON(lock->ast_pending);
2865                                 BUG_ON(lock->bast_pending);
2866                                 dlm_lockres_clear_refmap_bit(lock->ml.node, res);
2867                                 list_del_init(&lock->list);
2868                                 dlm_lock_put(lock);
2869                                 /* In a normal unlock, we would have added a
2870                                  * DLM_UNLOCK_FREE_LOCK action. Force it. */
2871                                 dlm_lock_put(lock);
2872                         }
2873                 }
2874                 queue++;
2875         }
2876         bit = 0;
2877         while (1) {
2878                 bit = find_next_bit(res->refmap, O2NM_MAX_NODES, bit);
2879                 if (bit >= O2NM_MAX_NODES)
2880                         break;
2881                 /* do not clear the local node reference, if there is a
2882                  * process holding this, let it drop the ref itself */
2883                 if (bit != dlm->node_num) {
2884                         mlog(0, "%s:%.*s: node %u had a ref to this "
2885                              "migrating lockres, clearing\n", dlm->name,
2886                              res->lockname.len, res->lockname.name, bit);
2887                         dlm_lockres_clear_refmap_bit(bit, res);
2888                 }
2889                 bit++;
2890         }
2891 }
2892
2893 /* for now this is not too intelligent.  we will
2894  * need stats to make this do the right thing.
2895  * this just finds the first lock on one of the
2896  * queues and uses that node as the target. */
2897 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
2898                                     struct dlm_lock_resource *res)
2899 {
2900         int i;
2901         struct list_head *queue = &res->granted;
2902         struct dlm_lock *lock;
2903         int nodenum;
2904
2905         assert_spin_locked(&dlm->spinlock);
2906
2907         spin_lock(&res->spinlock);
2908         for (i=0; i<3; i++) {
2909                 list_for_each_entry(lock, queue, list) {
2910                         /* up to the caller to make sure this node
2911                          * is alive */
2912                         if (lock->ml.node != dlm->node_num) {
2913                                 spin_unlock(&res->spinlock);
2914                                 return lock->ml.node;
2915                         }
2916                 }
2917                 queue++;
2918         }
2919         spin_unlock(&res->spinlock);
2920         mlog(0, "have not found a suitable target yet! checking domain map\n");
2921
2922         /* ok now we're getting desperate.  pick anyone alive. */
2923         nodenum = -1;
2924         while (1) {
2925                 nodenum = find_next_bit(dlm->domain_map,
2926                                         O2NM_MAX_NODES, nodenum+1);
2927                 mlog(0, "found %d in domain map\n", nodenum);
2928                 if (nodenum >= O2NM_MAX_NODES)
2929                         break;
2930                 if (nodenum != dlm->node_num) {
2931                         mlog(0, "picking %d\n", nodenum);
2932                         return nodenum;
2933                 }
2934         }
2935
2936         mlog(0, "giving up.  no master to migrate to\n");
2937         return DLM_LOCK_RES_OWNER_UNKNOWN;
2938 }
2939
2940
2941
2942 /* this is called by the new master once all lockres
2943  * data has been received */
2944 static int dlm_do_migrate_request(struct dlm_ctxt *dlm,
2945                                   struct dlm_lock_resource *res,
2946                                   u8 master, u8 new_master,
2947                                   struct dlm_node_iter *iter)
2948 {
2949         struct dlm_migrate_request migrate;
2950         int ret, skip, status = 0;
2951         int nodenum;
2952
2953         memset(&migrate, 0, sizeof(migrate));
2954         migrate.namelen = res->lockname.len;
2955         memcpy(migrate.name, res->lockname.name, migrate.namelen);
2956         migrate.new_master = new_master;
2957         migrate.master = master;
2958
2959         ret = 0;
2960
2961         /* send message to all nodes, except the master and myself */
2962         while ((nodenum = dlm_node_iter_next(iter)) >= 0) {
2963                 if (nodenum == master ||
2964                     nodenum == new_master)
2965                         continue;
2966
2967                 /* We could race exit domain. If exited, skip. */
2968                 spin_lock(&dlm->spinlock);
2969                 skip = (!test_bit(nodenum, dlm->domain_map));
2970                 spin_unlock(&dlm->spinlock);
2971                 if (skip) {
2972                         clear_bit(nodenum, iter->node_map);
2973                         continue;
2974                 }
2975
2976                 ret = o2net_send_message(DLM_MIGRATE_REQUEST_MSG, dlm->key,
2977                                          &migrate, sizeof(migrate), nodenum,
2978                                          &status);
2979                 if (ret < 0) {
2980                         mlog(0, "migrate_request returned %d!\n", ret);
2981                         if (!dlm_is_host_down(ret)) {
2982                                 mlog(ML_ERROR, "unhandled error=%d!\n", ret);
2983                                 BUG();
2984                         }
2985                         clear_bit(nodenum, iter->node_map);
2986                         ret = 0;
2987                 } else if (status < 0) {
2988                         mlog(0, "migrate request (node %u) returned %d!\n",
2989                              nodenum, status);
2990                         ret = status;
2991                 } else if (status == DLM_MIGRATE_RESPONSE_MASTERY_REF) {
2992                         /* during the migration request we short-circuited
2993                          * the mastery of the lockres.  make sure we have
2994                          * a mastery ref for nodenum */
2995                         mlog(0, "%s:%.*s: need ref for node %u\n",
2996                              dlm->name, res->lockname.len, res->lockname.name,
2997                              nodenum);
2998                         spin_lock(&res->spinlock);
2999                         dlm_lockres_set_refmap_bit(nodenum, res);
3000                         spin_unlock(&res->spinlock);
3001                 }
3002         }
3003
3004         if (ret < 0)
3005                 mlog_errno(ret);
3006
3007         mlog(0, "returning ret=%d\n", ret);
3008         return ret;
3009 }
3010
3011
3012 /* if there is an existing mle for this lockres, we now know who the master is.
3013  * (the one who sent us *this* message) we can clear it up right away.
3014  * since the process that put the mle on the list still has a reference to it,
3015  * we can unhash it now, set the master and wake the process.  as a result,
3016  * we will have no mle in the list to start with.  now we can add an mle for
3017  * the migration and this should be the only one found for those scanning the
3018  * list.  */
3019 int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
3020                                 void **ret_data)
3021 {
3022         struct dlm_ctxt *dlm = data;
3023         struct dlm_lock_resource *res = NULL;
3024         struct dlm_migrate_request *migrate = (struct dlm_migrate_request *) msg->buf;
3025         struct dlm_master_list_entry *mle = NULL, *oldmle = NULL;
3026         const char *name;
3027         unsigned int namelen, hash;
3028         int ret = 0;
3029
3030         if (!dlm_grab(dlm))
3031                 return -EINVAL;
3032
3033         name = migrate->name;
3034         namelen = migrate->namelen;
3035         hash = dlm_lockid_hash(name, namelen);
3036
3037         /* preallocate.. if this fails, abort */
3038         mle = (struct dlm_master_list_entry *) kmem_cache_alloc(dlm_mle_cache,
3039                                                          GFP_NOFS);
3040
3041         if (!mle) {
3042                 ret = -ENOMEM;
3043                 goto leave;
3044         }
3045
3046         /* check for pre-existing lock */
3047         spin_lock(&dlm->spinlock);
3048         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
3049         spin_lock(&dlm->master_lock);
3050
3051         if (res) {
3052                 spin_lock(&res->spinlock);
3053                 if (res->state & DLM_LOCK_RES_RECOVERING) {
3054                         /* if all is working ok, this can only mean that we got
3055                         * a migrate request from a node that we now see as
3056                         * dead.  what can we do here?  drop it to the floor? */
3057                         spin_unlock(&res->spinlock);
3058                         mlog(ML_ERROR, "Got a migrate request, but the "
3059                              "lockres is marked as recovering!");
3060                         kmem_cache_free(dlm_mle_cache, mle);
3061                         ret = -EINVAL; /* need a better solution */
3062                         goto unlock;
3063                 }
3064                 res->state |= DLM_LOCK_RES_MIGRATING;
3065                 spin_unlock(&res->spinlock);
3066         }
3067
3068         /* ignore status.  only nonzero status would BUG. */
3069         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
3070                                     name, namelen,
3071                                     migrate->new_master,
3072                                     migrate->master);
3073
3074 unlock:
3075         spin_unlock(&dlm->master_lock);
3076         spin_unlock(&dlm->spinlock);
3077
3078         if (oldmle) {
3079                 /* master is known, detach if not already detached */
3080                 dlm_mle_detach_hb_events(dlm, oldmle);
3081                 dlm_put_mle(oldmle);
3082         }
3083
3084         if (res)
3085                 dlm_lockres_put(res);
3086 leave:
3087         dlm_put(dlm);
3088         return ret;
3089 }
3090
3091 /* must be holding dlm->spinlock and dlm->master_lock
3092  * when adding a migration mle, we can clear any other mles
3093  * in the master list because we know with certainty that
3094  * the master is "master".  so we remove any old mle from
3095  * the list after setting it's master field, and then add
3096  * the new migration mle.  this way we can hold with the rule
3097  * of having only one mle for a given lock name at all times. */
3098 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
3099                                  struct dlm_lock_resource *res,
3100                                  struct dlm_master_list_entry *mle,
3101                                  struct dlm_master_list_entry **oldmle,
3102                                  const char *name, unsigned int namelen,
3103                                  u8 new_master, u8 master)
3104 {
3105         int found;
3106         int ret = 0;
3107
3108         *oldmle = NULL;
3109
3110         mlog_entry_void();
3111
3112         assert_spin_locked(&dlm->spinlock);
3113         assert_spin_locked(&dlm->master_lock);
3114
3115         /* caller is responsible for any ref taken here on oldmle */
3116         found = dlm_find_mle(dlm, oldmle, (char *)name, namelen);
3117         if (found) {
3118                 struct dlm_master_list_entry *tmp = *oldmle;
3119                 spin_lock(&tmp->spinlock);
3120                 if (tmp->type == DLM_MLE_MIGRATION) {
3121                         if (master == dlm->node_num) {
3122                                 /* ah another process raced me to it */
3123                                 mlog(0, "tried to migrate %.*s, but some "
3124                                      "process beat me to it\n",
3125                                      namelen, name);
3126                                 ret = -EEXIST;
3127                         } else {
3128                                 /* bad.  2 NODES are trying to migrate! */
3129                                 mlog(ML_ERROR, "migration error  mle: "
3130                                      "master=%u new_master=%u // request: "
3131                                      "master=%u new_master=%u // "
3132                                      "lockres=%.*s\n",
3133                                      tmp->master, tmp->new_master,
3134                                      master, new_master,
3135                                      namelen, name);
3136                                 BUG();
3137                         }
3138                 } else {
3139                         /* this is essentially what assert_master does */
3140                         tmp->master = master;
3141                         atomic_set(&tmp->woken, 1);
3142                         wake_up(&tmp->wq);
3143                         /* remove it so that only one mle will be found */
3144                         __dlm_unlink_mle(dlm, tmp);
3145                         __dlm_mle_detach_hb_events(dlm, tmp);
3146                         ret = DLM_MIGRATE_RESPONSE_MASTERY_REF;
3147                         mlog(0, "%s:%.*s: master=%u, newmaster=%u, "
3148                             "telling master to get ref for cleared out mle "
3149                             "during migration\n", dlm->name, namelen, name,
3150                             master, new_master);
3151                 }
3152                 spin_unlock(&tmp->spinlock);
3153         }
3154
3155         /* now add a migration mle to the tail of the list */
3156         dlm_init_mle(mle, DLM_MLE_MIGRATION, dlm, res, name, namelen);
3157         mle->new_master = new_master;
3158         /* the new master will be sending an assert master for this.
3159          * at that point we will get the refmap reference */
3160         mle->master = master;
3161         /* do this for consistency with other mle types */
3162         set_bit(new_master, mle->maybe_map);
3163         __dlm_insert_mle(dlm, mle);
3164
3165         return ret;
3166 }
3167
3168 /*
3169  * Sets the owner of the lockres, associated to the mle, to UNKNOWN
3170  */
3171 static struct dlm_lock_resource *dlm_reset_mleres_owner(struct dlm_ctxt *dlm,
3172                                         struct dlm_master_list_entry *mle)
3173 {
3174         struct dlm_lock_resource *res;
3175
3176         /* Find the lockres associated to the mle and set its owner to UNK */
3177         res = __dlm_lookup_lockres(dlm, mle->mname, mle->mnamelen,
3178                                    mle->mnamehash);
3179         if (res) {
3180                 spin_unlock(&dlm->master_lock);
3181
3182                 /* move lockres onto recovery list */
3183                 spin_lock(&res->spinlock);
3184                 dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
3185                 dlm_move_lockres_to_recovery_list(dlm, res);
3186                 spin_unlock(&res->spinlock);
3187                 dlm_lockres_put(res);
3188
3189                 /* about to get rid of mle, detach from heartbeat */
3190                 __dlm_mle_detach_hb_events(dlm, mle);
3191
3192                 /* dump the mle */
3193                 spin_lock(&dlm->master_lock);
3194                 __dlm_put_mle(mle);
3195                 spin_unlock(&dlm->master_lock);
3196         }
3197
3198         return res;
3199 }
3200
3201 static void dlm_clean_migration_mle(struct dlm_ctxt *dlm,
3202                                     struct dlm_master_list_entry *mle)
3203 {
3204         __dlm_mle_detach_hb_events(dlm, mle);
3205
3206         spin_lock(&mle->spinlock);
3207         __dlm_unlink_mle(dlm, mle);
3208         atomic_set(&mle->woken, 1);
3209         spin_unlock(&mle->spinlock);
3210
3211         wake_up(&mle->wq);
3212 }
3213
3214 static void dlm_clean_block_mle(struct dlm_ctxt *dlm,
3215                                 struct dlm_master_list_entry *mle, u8 dead_node)
3216 {
3217         int bit;
3218
3219         BUG_ON(mle->type != DLM_MLE_BLOCK);
3220
3221         spin_lock(&mle->spinlock);
3222         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
3223         if (bit != dead_node) {
3224                 mlog(0, "mle found, but dead node %u would not have been "
3225                      "master\n", dead_node);
3226                 spin_unlock(&mle->spinlock);
3227         } else {
3228                 /* Must drop the refcount by one since the assert_master will
3229                  * never arrive. This may result in the mle being unlinked and
3230                  * freed, but there may still be a process waiting in the
3231                  * dlmlock path which is fine. */
3232                 mlog(0, "node %u was expected master\n", dead_node);
3233                 atomic_set(&mle->woken, 1);
3234                 spin_unlock(&mle->spinlock);
3235                 wake_up(&mle->wq);
3236
3237                 /* Do not need events any longer, so detach from heartbeat */
3238                 __dlm_mle_detach_hb_events(dlm, mle);
3239                 __dlm_put_mle(mle);
3240         }
3241 }
3242
3243 void dlm_clean_master_list(struct dlm_ctxt *dlm, u8 dead_node)
3244 {
3245         struct dlm_master_list_entry *mle;
3246         struct dlm_lock_resource *res;
3247         struct hlist_head *bucket;
3248         struct hlist_node *list;
3249         unsigned int i;
3250
3251         mlog_entry("dlm=%s, dead node=%u\n", dlm->name, dead_node);
3252 top:
3253         assert_spin_locked(&dlm->spinlock);
3254
3255         /* clean the master list */
3256         spin_lock(&dlm->master_lock);
3257         for (i = 0; i < DLM_HASH_BUCKETS; i++) {
3258                 bucket = dlm_master_hash(dlm, i);
3259                 hlist_for_each(list, bucket) {
3260                         mle = hlist_entry(list, struct dlm_master_list_entry,
3261                                           master_hash_node);
3262
3263                         BUG_ON(mle->type != DLM_MLE_BLOCK &&
3264                                mle->type != DLM_MLE_MASTER &&
3265                                mle->type != DLM_MLE_MIGRATION);
3266
3267                         /* MASTER mles are initiated locally. The waiting
3268                          * process will notice the node map change shortly.
3269                          * Let that happen as normal. */
3270                         if (mle->type == DLM_MLE_MASTER)
3271                                 continue;
3272
3273                         /* BLOCK mles are initiated by other nodes. Need to
3274                          * clean up if the dead node would have been the
3275                          * master. */
3276                         if (mle->type == DLM_MLE_BLOCK) {
3277                                 dlm_clean_block_mle(dlm, mle, dead_node);
3278                                 continue;
3279                         }
3280
3281                         /* Everything else is a MIGRATION mle */
3282
3283                         /* The rule for MIGRATION mles is that the master
3284                          * becomes UNKNOWN if *either* the original or the new
3285                          * master dies. All UNKNOWN lockres' are sent to
3286                          * whichever node becomes the recovery master. The new
3287                          * master is responsible for determining if there is
3288                          * still a master for this lockres, or if he needs to
3289                          * take over mastery. Either way, this node should
3290                          * expect another message to resolve this. */
3291
3292                         if (mle->master != dead_node &&
3293                             mle->new_master != dead_node)
3294                                 continue;
3295
3296                         /* If we have reached this point, this mle needs to be
3297                          * removed from the list and freed. */
3298                         dlm_clean_migration_mle(dlm, mle);
3299
3300                         mlog(0, "%s: node %u died during migration from "
3301                              "%u to %u!\n", dlm->name, dead_node, mle->master,
3302                              mle->new_master);
3303
3304                         /* If we find a lockres associated with the mle, we've
3305                          * hit this rare case that messes up our lock ordering.
3306                          * If so, we need to drop the master lock so that we can
3307                          * take the lockres lock, meaning that we will have to
3308                          * restart from the head of list. */
3309                         res = dlm_reset_mleres_owner(dlm, mle);
3310                         if (res)
3311                                 /* restart */
3312                                 goto top;
3313
3314                         /* This may be the last reference */
3315                         __dlm_put_mle(mle);
3316                 }
3317         }
3318         spin_unlock(&dlm->master_lock);
3319 }
3320
3321 int dlm_finish_migration(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
3322                          u8 old_master)
3323 {
3324         struct dlm_node_iter iter;
3325         int ret = 0;
3326
3327         spin_lock(&dlm->spinlock);
3328         dlm_node_iter_init(dlm->domain_map, &iter);
3329         clear_bit(old_master, iter.node_map);
3330         clear_bit(dlm->node_num, iter.node_map);
3331         spin_unlock(&dlm->spinlock);
3332
3333         /* ownership of the lockres is changing.  account for the
3334          * mastery reference here since old_master will briefly have
3335          * a reference after the migration completes */
3336         spin_lock(&res->spinlock);
3337         dlm_lockres_set_refmap_bit(old_master, res);
3338         spin_unlock(&res->spinlock);
3339
3340         mlog(0, "now time to do a migrate request to other nodes\n");
3341         ret = dlm_do_migrate_request(dlm, res, old_master,
3342                                      dlm->node_num, &iter);
3343         if (ret < 0) {
3344                 mlog_errno(ret);
3345                 goto leave;
3346         }
3347
3348         mlog(0, "doing assert master of %.*s to all except the original node\n",
3349              res->lockname.len, res->lockname.name);
3350         /* this call now finishes out the nodemap
3351          * even if one or more nodes die */
3352         ret = dlm_do_assert_master(dlm, res, iter.node_map,
3353                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
3354         if (ret < 0) {
3355                 /* no longer need to retry.  all living nodes contacted. */
3356                 mlog_errno(ret);
3357                 ret = 0;
3358         }
3359
3360         memset(iter.node_map, 0, sizeof(iter.node_map));
3361         set_bit(old_master, iter.node_map);
3362         mlog(0, "doing assert master of %.*s back to %u\n",
3363              res->lockname.len, res->lockname.name, old_master);
3364         ret = dlm_do_assert_master(dlm, res, iter.node_map,
3365                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
3366         if (ret < 0) {
3367                 mlog(0, "assert master to original master failed "
3368                      "with %d.\n", ret);
3369                 /* the only nonzero status here would be because of
3370                  * a dead original node.  we're done. */
3371                 ret = 0;
3372         }
3373
3374         /* all done, set the owner, clear the flag */
3375         spin_lock(&res->spinlock);
3376         dlm_set_lockres_owner(dlm, res, dlm->node_num);
3377         res->state &= ~DLM_LOCK_RES_MIGRATING;
3378         spin_unlock(&res->spinlock);
3379         /* re-dirty it on the new master */
3380         dlm_kick_thread(dlm, res);
3381         wake_up(&res->wq);
3382 leave:
3383         return ret;
3384 }
3385
3386 /*
3387  * LOCKRES AST REFCOUNT
3388  * this is integral to migration
3389  */
3390
3391 /* for future intent to call an ast, reserve one ahead of time.
3392  * this should be called only after waiting on the lockres
3393  * with dlm_wait_on_lockres, and while still holding the
3394  * spinlock after the call. */
3395 void __dlm_lockres_reserve_ast(struct dlm_lock_resource *res)
3396 {
3397         assert_spin_locked(&res->spinlock);
3398         if (res->state & DLM_LOCK_RES_MIGRATING) {
3399                 __dlm_print_one_lock_resource(res);
3400         }
3401         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
3402
3403         atomic_inc(&res->asts_reserved);
3404 }
3405
3406 /*
3407  * used to drop the reserved ast, either because it went unused,
3408  * or because the ast/bast was actually called.
3409  *
3410  * also, if there is a pending migration on this lockres,
3411  * and this was the last pending ast on the lockres,
3412  * atomically set the MIGRATING flag before we drop the lock.
3413  * this is how we ensure that migration can proceed with no
3414  * asts in progress.  note that it is ok if the state of the
3415  * queues is such that a lock should be granted in the future
3416  * or that a bast should be fired, because the new master will
3417  * shuffle the lists on this lockres as soon as it is migrated.
3418  */
3419 void dlm_lockres_release_ast(struct dlm_ctxt *dlm,
3420                              struct dlm_lock_resource *res)
3421 {
3422         if (!atomic_dec_and_lock(&res->asts_reserved, &res->spinlock))
3423                 return;
3424
3425         if (!res->migration_pending) {
3426                 spin_unlock(&res->spinlock);
3427                 return;
3428         }
3429
3430         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
3431         res->migration_pending = 0;
3432         res->state |= DLM_LOCK_RES_MIGRATING;
3433         spin_unlock(&res->spinlock);
3434         wake_up(&res->wq);
3435         wake_up(&dlm->migration_wq);
3436 }