[PATCH] ocfs2: use hlists for lockres hash
[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/utsname.h>
34 #include <linux/init.h>
35 #include <linux/sysctl.h>
36 #include <linux/random.h>
37 #include <linux/blkdev.h>
38 #include <linux/socket.h>
39 #include <linux/inet.h>
40 #include <linux/spinlock.h>
41 #include <linux/delay.h>
42
43
44 #include "cluster/heartbeat.h"
45 #include "cluster/nodemanager.h"
46 #include "cluster/tcp.h"
47
48 #include "dlmapi.h"
49 #include "dlmcommon.h"
50 #include "dlmdebug.h"
51 #include "dlmdomain.h"
52
53 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
54 #include "cluster/masklog.h"
55
56 enum dlm_mle_type {
57         DLM_MLE_BLOCK,
58         DLM_MLE_MASTER,
59         DLM_MLE_MIGRATION
60 };
61
62 struct dlm_lock_name
63 {
64         u8 len;
65         u8 name[DLM_LOCKID_NAME_MAX];
66 };
67
68 struct dlm_master_list_entry
69 {
70         struct list_head list;
71         struct list_head hb_events;
72         struct dlm_ctxt *dlm;
73         spinlock_t spinlock;
74         wait_queue_head_t wq;
75         atomic_t woken;
76         struct kref mle_refs;
77         unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
78         unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
79         unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
80         unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
81         u8 master;
82         u8 new_master;
83         enum dlm_mle_type type;
84         struct o2hb_callback_func mle_hb_up;
85         struct o2hb_callback_func mle_hb_down;
86         union {
87                 struct dlm_lock_resource *res;
88                 struct dlm_lock_name name;
89         } u;
90 };
91
92 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
93                               struct dlm_master_list_entry *mle,
94                               struct o2nm_node *node,
95                               int idx);
96 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
97                             struct dlm_master_list_entry *mle,
98                             struct o2nm_node *node,
99                             int idx);
100
101 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data);
102 static int dlm_do_assert_master(struct dlm_ctxt *dlm, const char *lockname,
103                                 unsigned int namelen, void *nodemap,
104                                 u32 flags);
105
106 static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
107                                 struct dlm_master_list_entry *mle,
108                                 const char *name,
109                                 unsigned int namelen)
110 {
111         struct dlm_lock_resource *res;
112
113         if (dlm != mle->dlm)
114                 return 0;
115
116         if (mle->type == DLM_MLE_BLOCK ||
117             mle->type == DLM_MLE_MIGRATION) {
118                 if (namelen != mle->u.name.len ||
119                     memcmp(name, mle->u.name.name, namelen)!=0)
120                         return 0;
121         } else {
122                 res = mle->u.res;
123                 if (namelen != res->lockname.len ||
124                     memcmp(res->lockname.name, name, namelen) != 0)
125                         return 0;
126         }
127         return 1;
128 }
129
130 #if 0
131 /* Code here is included but defined out as it aids debugging */
132
133 void dlm_print_one_mle(struct dlm_master_list_entry *mle)
134 {
135         int i = 0, refs;
136         char *type;
137         char attached;
138         u8 master;
139         unsigned int namelen;
140         const char *name;
141         struct kref *k;
142
143         k = &mle->mle_refs;
144         if (mle->type == DLM_MLE_BLOCK)
145                 type = "BLK";
146         else if (mle->type == DLM_MLE_MASTER)
147                 type = "MAS";
148         else
149                 type = "MIG";
150         refs = atomic_read(&k->refcount);
151         master = mle->master;
152         attached = (list_empty(&mle->hb_events) ? 'N' : 'Y');
153
154         if (mle->type != DLM_MLE_MASTER) {
155                 namelen = mle->u.name.len;
156                 name = mle->u.name.name;
157         } else {
158                 namelen = mle->u.res->lockname.len;
159                 name = mle->u.res->lockname.name;
160         }
161
162         mlog(ML_NOTICE, "  #%3d: %3s  %3d  %3u   %3u %c    (%d)%.*s\n",
163                   i, type, refs, master, mle->new_master, attached,
164                   namelen, namelen, name);
165 }
166
167 static void dlm_dump_mles(struct dlm_ctxt *dlm)
168 {
169         struct dlm_master_list_entry *mle;
170         struct list_head *iter;
171         
172         mlog(ML_NOTICE, "dumping all mles for domain %s:\n", dlm->name);
173         mlog(ML_NOTICE, "  ####: type refs owner new events? lockname nodemap votemap respmap maybemap\n");
174         spin_lock(&dlm->master_lock);
175         list_for_each(iter, &dlm->master_list) {
176                 mle = list_entry(iter, struct dlm_master_list_entry, list);
177                 dlm_print_one_mle(mle);
178         }
179         spin_unlock(&dlm->master_lock);
180 }
181
182 int dlm_dump_all_mles(const char __user *data, unsigned int len)
183 {
184         struct list_head *iter;
185         struct dlm_ctxt *dlm;
186
187         spin_lock(&dlm_domain_lock);
188         list_for_each(iter, &dlm_domains) {
189                 dlm = list_entry (iter, struct dlm_ctxt, list);
190                 mlog(ML_NOTICE, "found dlm: %p, name=%s\n", dlm, dlm->name);
191                 dlm_dump_mles(dlm);
192         }
193         spin_unlock(&dlm_domain_lock);
194         return len;
195 }
196 EXPORT_SYMBOL_GPL(dlm_dump_all_mles);
197
198 #endif  /*  0  */
199
200
201 static kmem_cache_t *dlm_mle_cache = NULL;
202
203
204 static void dlm_mle_release(struct kref *kref);
205 static void dlm_init_mle(struct dlm_master_list_entry *mle,
206                         enum dlm_mle_type type,
207                         struct dlm_ctxt *dlm,
208                         struct dlm_lock_resource *res,
209                         const char *name,
210                         unsigned int namelen);
211 static void dlm_put_mle(struct dlm_master_list_entry *mle);
212 static void __dlm_put_mle(struct dlm_master_list_entry *mle);
213 static int dlm_find_mle(struct dlm_ctxt *dlm,
214                         struct dlm_master_list_entry **mle,
215                         char *name, unsigned int namelen);
216
217 static int dlm_do_master_request(struct dlm_master_list_entry *mle, int to);
218
219
220 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
221                                      struct dlm_lock_resource *res,
222                                      struct dlm_master_list_entry *mle,
223                                      int *blocked);
224 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
225                                     struct dlm_lock_resource *res,
226                                     struct dlm_master_list_entry *mle,
227                                     int blocked);
228 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
229                                  struct dlm_lock_resource *res,
230                                  struct dlm_master_list_entry *mle,
231                                  struct dlm_master_list_entry **oldmle,
232                                  const char *name, unsigned int namelen,
233                                  u8 new_master, u8 master);
234
235 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
236                                     struct dlm_lock_resource *res);
237 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
238                                       struct dlm_lock_resource *res);
239 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
240                                        struct dlm_lock_resource *res,
241                                        u8 target);
242
243
244 int dlm_is_host_down(int errno)
245 {
246         switch (errno) {
247                 case -EBADF:
248                 case -ECONNREFUSED:
249                 case -ENOTCONN:
250                 case -ECONNRESET:
251                 case -EPIPE:
252                 case -EHOSTDOWN:
253                 case -EHOSTUNREACH:
254                 case -ETIMEDOUT:
255                 case -ECONNABORTED:
256                 case -ENETDOWN:
257                 case -ENETUNREACH:
258                 case -ENETRESET:
259                 case -ESHUTDOWN:
260                 case -ENOPROTOOPT:
261                 case -EINVAL:   /* if returned from our tcp code,
262                                    this means there is no socket */
263                         return 1;
264         }
265         return 0;
266 }
267
268
269 /*
270  * MASTER LIST FUNCTIONS
271  */
272
273
274 /*
275  * regarding master list entries and heartbeat callbacks:
276  *
277  * in order to avoid sleeping and allocation that occurs in
278  * heartbeat, master list entries are simply attached to the
279  * dlm's established heartbeat callbacks.  the mle is attached
280  * when it is created, and since the dlm->spinlock is held at
281  * that time, any heartbeat event will be properly discovered
282  * by the mle.  the mle needs to be detached from the
283  * dlm->mle_hb_events list as soon as heartbeat events are no
284  * longer useful to the mle, and before the mle is freed.
285  *
286  * as a general rule, heartbeat events are no longer needed by
287  * the mle once an "answer" regarding the lock master has been
288  * received.
289  */
290 static inline void __dlm_mle_attach_hb_events(struct dlm_ctxt *dlm,
291                                               struct dlm_master_list_entry *mle)
292 {
293         assert_spin_locked(&dlm->spinlock);
294
295         list_add_tail(&mle->hb_events, &dlm->mle_hb_events);
296 }
297
298
299 static inline void __dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
300                                               struct dlm_master_list_entry *mle)
301 {
302         if (!list_empty(&mle->hb_events))
303                 list_del_init(&mle->hb_events);
304 }
305
306
307 static inline void dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
308                                             struct dlm_master_list_entry *mle)
309 {
310         spin_lock(&dlm->spinlock);
311         __dlm_mle_detach_hb_events(dlm, mle);
312         spin_unlock(&dlm->spinlock);
313 }
314
315 /* remove from list and free */
316 static void __dlm_put_mle(struct dlm_master_list_entry *mle)
317 {
318         struct dlm_ctxt *dlm;
319         dlm = mle->dlm;
320
321         assert_spin_locked(&dlm->spinlock);
322         assert_spin_locked(&dlm->master_lock);
323         BUG_ON(!atomic_read(&mle->mle_refs.refcount));
324
325         kref_put(&mle->mle_refs, dlm_mle_release);
326 }
327
328
329 /* must not have any spinlocks coming in */
330 static void dlm_put_mle(struct dlm_master_list_entry *mle)
331 {
332         struct dlm_ctxt *dlm;
333         dlm = mle->dlm;
334
335         spin_lock(&dlm->spinlock);
336         spin_lock(&dlm->master_lock);
337         __dlm_put_mle(mle);
338         spin_unlock(&dlm->master_lock);
339         spin_unlock(&dlm->spinlock);
340 }
341
342 static inline void dlm_get_mle(struct dlm_master_list_entry *mle)
343 {
344         kref_get(&mle->mle_refs);
345 }
346
347 static void dlm_init_mle(struct dlm_master_list_entry *mle,
348                         enum dlm_mle_type type,
349                         struct dlm_ctxt *dlm,
350                         struct dlm_lock_resource *res,
351                         const char *name,
352                         unsigned int namelen)
353 {
354         assert_spin_locked(&dlm->spinlock);
355
356         mle->dlm = dlm;
357         mle->type = type;
358         INIT_LIST_HEAD(&mle->list);
359         INIT_LIST_HEAD(&mle->hb_events);
360         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
361         spin_lock_init(&mle->spinlock);
362         init_waitqueue_head(&mle->wq);
363         atomic_set(&mle->woken, 0);
364         kref_init(&mle->mle_refs);
365         memset(mle->response_map, 0, sizeof(mle->response_map));
366         mle->master = O2NM_MAX_NODES;
367         mle->new_master = O2NM_MAX_NODES;
368
369         if (mle->type == DLM_MLE_MASTER) {
370                 BUG_ON(!res);
371                 mle->u.res = res;
372         } else if (mle->type == DLM_MLE_BLOCK) {
373                 BUG_ON(!name);
374                 memcpy(mle->u.name.name, name, namelen);
375                 mle->u.name.len = namelen;
376         } else /* DLM_MLE_MIGRATION */ {
377                 BUG_ON(!name);
378                 memcpy(mle->u.name.name, name, namelen);
379                 mle->u.name.len = namelen;
380         }
381
382         /* copy off the node_map and register hb callbacks on our copy */
383         memcpy(mle->node_map, dlm->domain_map, sizeof(mle->node_map));
384         memcpy(mle->vote_map, dlm->domain_map, sizeof(mle->vote_map));
385         clear_bit(dlm->node_num, mle->vote_map);
386         clear_bit(dlm->node_num, mle->node_map);
387
388         /* attach the mle to the domain node up/down events */
389         __dlm_mle_attach_hb_events(dlm, mle);
390 }
391
392
393 /* returns 1 if found, 0 if not */
394 static int dlm_find_mle(struct dlm_ctxt *dlm,
395                         struct dlm_master_list_entry **mle,
396                         char *name, unsigned int namelen)
397 {
398         struct dlm_master_list_entry *tmpmle;
399         struct list_head *iter;
400
401         assert_spin_locked(&dlm->master_lock);
402
403         list_for_each(iter, &dlm->master_list) {
404                 tmpmle = list_entry(iter, struct dlm_master_list_entry, list);
405                 if (!dlm_mle_equal(dlm, tmpmle, name, namelen))
406                         continue;
407                 dlm_get_mle(tmpmle);
408                 *mle = tmpmle;
409                 return 1;
410         }
411         return 0;
412 }
413
414 void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up)
415 {
416         struct dlm_master_list_entry *mle;
417         struct list_head *iter;
418
419         assert_spin_locked(&dlm->spinlock);
420         
421         list_for_each(iter, &dlm->mle_hb_events) {
422                 mle = list_entry(iter, struct dlm_master_list_entry, 
423                                  hb_events);
424                 if (node_up)
425                         dlm_mle_node_up(dlm, mle, NULL, idx);
426                 else
427                         dlm_mle_node_down(dlm, mle, NULL, idx);
428         }
429 }
430
431 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
432                               struct dlm_master_list_entry *mle,
433                               struct o2nm_node *node, int idx)
434 {
435         spin_lock(&mle->spinlock);
436
437         if (!test_bit(idx, mle->node_map))
438                 mlog(0, "node %u already removed from nodemap!\n", idx);
439         else
440                 clear_bit(idx, mle->node_map);
441
442         spin_unlock(&mle->spinlock);
443 }
444
445 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
446                             struct dlm_master_list_entry *mle,
447                             struct o2nm_node *node, int idx)
448 {
449         spin_lock(&mle->spinlock);
450
451         if (test_bit(idx, mle->node_map))
452                 mlog(0, "node %u already in node map!\n", idx);
453         else
454                 set_bit(idx, mle->node_map);
455
456         spin_unlock(&mle->spinlock);
457 }
458
459
460 int dlm_init_mle_cache(void)
461 {
462         dlm_mle_cache = kmem_cache_create("dlm_mle_cache",
463                                           sizeof(struct dlm_master_list_entry),
464                                           0, SLAB_HWCACHE_ALIGN,
465                                           NULL, NULL);
466         if (dlm_mle_cache == NULL)
467                 return -ENOMEM;
468         return 0;
469 }
470
471 void dlm_destroy_mle_cache(void)
472 {
473         if (dlm_mle_cache)
474                 kmem_cache_destroy(dlm_mle_cache);
475 }
476
477 static void dlm_mle_release(struct kref *kref)
478 {
479         struct dlm_master_list_entry *mle;
480         struct dlm_ctxt *dlm;
481
482         mlog_entry_void();
483
484         mle = container_of(kref, struct dlm_master_list_entry, mle_refs);
485         dlm = mle->dlm;
486
487         if (mle->type != DLM_MLE_MASTER) {
488                 mlog(0, "calling mle_release for %.*s, type %d\n",
489                      mle->u.name.len, mle->u.name.name, mle->type);
490         } else {
491                 mlog(0, "calling mle_release for %.*s, type %d\n",
492                      mle->u.res->lockname.len,
493                      mle->u.res->lockname.name, mle->type);
494         }
495         assert_spin_locked(&dlm->spinlock);
496         assert_spin_locked(&dlm->master_lock);
497
498         /* remove from list if not already */
499         if (!list_empty(&mle->list))
500                 list_del_init(&mle->list);
501
502         /* detach the mle from the domain node up/down events */
503         __dlm_mle_detach_hb_events(dlm, mle);
504
505         /* NOTE: kfree under spinlock here.
506          * if this is bad, we can move this to a freelist. */
507         kmem_cache_free(dlm_mle_cache, mle);
508 }
509
510
511 /*
512  * LOCK RESOURCE FUNCTIONS
513  */
514
515 static void dlm_set_lockres_owner(struct dlm_ctxt *dlm,
516                                   struct dlm_lock_resource *res,
517                                   u8 owner)
518 {
519         assert_spin_locked(&res->spinlock);
520
521         mlog_entry("%.*s, %u\n", res->lockname.len, res->lockname.name, owner);
522
523         if (owner == dlm->node_num)
524                 atomic_inc(&dlm->local_resources);
525         else if (owner == DLM_LOCK_RES_OWNER_UNKNOWN)
526                 atomic_inc(&dlm->unknown_resources);
527         else
528                 atomic_inc(&dlm->remote_resources);
529
530         res->owner = owner;
531 }
532
533 void dlm_change_lockres_owner(struct dlm_ctxt *dlm,
534                               struct dlm_lock_resource *res, u8 owner)
535 {
536         assert_spin_locked(&res->spinlock);
537
538         if (owner == res->owner)
539                 return;
540
541         if (res->owner == dlm->node_num)
542                 atomic_dec(&dlm->local_resources);
543         else if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN)
544                 atomic_dec(&dlm->unknown_resources);
545         else
546                 atomic_dec(&dlm->remote_resources);
547
548         dlm_set_lockres_owner(dlm, res, owner);
549 }
550
551
552 static void dlm_lockres_release(struct kref *kref)
553 {
554         struct dlm_lock_resource *res;
555
556         res = container_of(kref, struct dlm_lock_resource, refs);
557
558         /* This should not happen -- all lockres' have a name
559          * associated with them at init time. */
560         BUG_ON(!res->lockname.name);
561
562         mlog(0, "destroying lockres %.*s\n", res->lockname.len,
563              res->lockname.name);
564
565         /* By the time we're ready to blow this guy away, we shouldn't
566          * be on any lists. */
567         BUG_ON(!hlist_unhashed(&res->hash_node));
568         BUG_ON(!list_empty(&res->granted));
569         BUG_ON(!list_empty(&res->converting));
570         BUG_ON(!list_empty(&res->blocked));
571         BUG_ON(!list_empty(&res->dirty));
572         BUG_ON(!list_empty(&res->recovering));
573         BUG_ON(!list_empty(&res->purge));
574
575         kfree(res->lockname.name);
576
577         kfree(res);
578 }
579
580 void dlm_lockres_get(struct dlm_lock_resource *res)
581 {
582         kref_get(&res->refs);
583 }
584
585 void dlm_lockres_put(struct dlm_lock_resource *res)
586 {
587         kref_put(&res->refs, dlm_lockres_release);
588 }
589
590 static void dlm_init_lockres(struct dlm_ctxt *dlm,
591                              struct dlm_lock_resource *res,
592                              const char *name, unsigned int namelen)
593 {
594         char *qname;
595
596         /* If we memset here, we lose our reference to the kmalloc'd
597          * res->lockname.name, so be sure to init every field
598          * correctly! */
599
600         qname = (char *) res->lockname.name;
601         memcpy(qname, name, namelen);
602
603         res->lockname.len = namelen;
604         res->lockname.hash = full_name_hash(name, namelen);
605
606         init_waitqueue_head(&res->wq);
607         spin_lock_init(&res->spinlock);
608         INIT_HLIST_NODE(&res->hash_node);
609         INIT_LIST_HEAD(&res->granted);
610         INIT_LIST_HEAD(&res->converting);
611         INIT_LIST_HEAD(&res->blocked);
612         INIT_LIST_HEAD(&res->dirty);
613         INIT_LIST_HEAD(&res->recovering);
614         INIT_LIST_HEAD(&res->purge);
615         atomic_set(&res->asts_reserved, 0);
616         res->migration_pending = 0;
617
618         kref_init(&res->refs);
619
620         /* just for consistency */
621         spin_lock(&res->spinlock);
622         dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
623         spin_unlock(&res->spinlock);
624
625         res->state = DLM_LOCK_RES_IN_PROGRESS;
626
627         res->last_used = 0;
628
629         memset(res->lvb, 0, DLM_LVB_LEN);
630 }
631
632 struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
633                                    const char *name,
634                                    unsigned int namelen)
635 {
636         struct dlm_lock_resource *res;
637
638         res = kmalloc(sizeof(struct dlm_lock_resource), GFP_KERNEL);
639         if (!res)
640                 return NULL;
641
642         res->lockname.name = kmalloc(namelen, GFP_KERNEL);
643         if (!res->lockname.name) {
644                 kfree(res);
645                 return NULL;
646         }
647
648         dlm_init_lockres(dlm, res, name, namelen);
649         return res;
650 }
651
652 /*
653  * lookup a lock resource by name.
654  * may already exist in the hashtable.
655  * lockid is null terminated
656  *
657  * if not, allocate enough for the lockres and for
658  * the temporary structure used in doing the mastering.
659  *
660  * also, do a lookup in the dlm->master_list to see
661  * if another node has begun mastering the same lock.
662  * if so, there should be a block entry in there
663  * for this name, and we should *not* attempt to master
664  * the lock here.   need to wait around for that node
665  * to assert_master (or die).
666  *
667  */
668 struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm,
669                                           const char *lockid,
670                                           int flags)
671 {
672         struct dlm_lock_resource *tmpres=NULL, *res=NULL;
673         struct dlm_master_list_entry *mle = NULL;
674         struct dlm_master_list_entry *alloc_mle = NULL;
675         int blocked = 0;
676         int ret, nodenum;
677         struct dlm_node_iter iter;
678         unsigned int namelen;
679         int tries = 0;
680
681         BUG_ON(!lockid);
682
683         namelen = strlen(lockid);
684
685         mlog(0, "get lockres %s (len %d)\n", lockid, namelen);
686
687 lookup:
688         spin_lock(&dlm->spinlock);
689         tmpres = __dlm_lookup_lockres(dlm, lockid, namelen);
690         if (tmpres) {
691                 spin_unlock(&dlm->spinlock);
692                 mlog(0, "found in hash!\n");
693                 if (res)
694                         dlm_lockres_put(res);
695                 res = tmpres;
696                 goto leave;
697         }
698
699         if (!res) {
700                 spin_unlock(&dlm->spinlock);
701                 mlog(0, "allocating a new resource\n");
702                 /* nothing found and we need to allocate one. */
703                 alloc_mle = (struct dlm_master_list_entry *)
704                         kmem_cache_alloc(dlm_mle_cache, GFP_KERNEL);
705                 if (!alloc_mle)
706                         goto leave;
707                 res = dlm_new_lockres(dlm, lockid, namelen);
708                 if (!res)
709                         goto leave;
710                 goto lookup;
711         }
712
713         mlog(0, "no lockres found, allocated our own: %p\n", res);
714
715         if (flags & LKM_LOCAL) {
716                 /* caller knows it's safe to assume it's not mastered elsewhere
717                  * DONE!  return right away */
718                 spin_lock(&res->spinlock);
719                 dlm_change_lockres_owner(dlm, res, dlm->node_num);
720                 __dlm_insert_lockres(dlm, res);
721                 spin_unlock(&res->spinlock);
722                 spin_unlock(&dlm->spinlock);
723                 /* lockres still marked IN_PROGRESS */
724                 goto wake_waiters;
725         }
726
727         /* check master list to see if another node has started mastering it */
728         spin_lock(&dlm->master_lock);
729
730         /* if we found a block, wait for lock to be mastered by another node */
731         blocked = dlm_find_mle(dlm, &mle, (char *)lockid, namelen);
732         if (blocked) {
733                 if (mle->type == DLM_MLE_MASTER) {
734                         mlog(ML_ERROR, "master entry for nonexistent lock!\n");
735                         BUG();
736                 } else if (mle->type == DLM_MLE_MIGRATION) {
737                         /* migration is in progress! */
738                         /* the good news is that we now know the
739                          * "current" master (mle->master). */
740
741                         spin_unlock(&dlm->master_lock);
742                         assert_spin_locked(&dlm->spinlock);
743
744                         /* set the lockres owner and hash it */
745                         spin_lock(&res->spinlock);
746                         dlm_set_lockres_owner(dlm, res, mle->master);
747                         __dlm_insert_lockres(dlm, res);
748                         spin_unlock(&res->spinlock);
749                         spin_unlock(&dlm->spinlock);
750
751                         /* master is known, detach */
752                         dlm_mle_detach_hb_events(dlm, mle);
753                         dlm_put_mle(mle);
754                         mle = NULL;
755                         goto wake_waiters;
756                 }
757         } else {
758                 /* go ahead and try to master lock on this node */
759                 mle = alloc_mle;
760                 /* make sure this does not get freed below */
761                 alloc_mle = NULL;
762                 dlm_init_mle(mle, DLM_MLE_MASTER, dlm, res, NULL, 0);
763                 set_bit(dlm->node_num, mle->maybe_map);
764                 list_add(&mle->list, &dlm->master_list);
765         }
766
767         /* at this point there is either a DLM_MLE_BLOCK or a
768          * DLM_MLE_MASTER on the master list, so it's safe to add the
769          * lockres to the hashtable.  anyone who finds the lock will
770          * still have to wait on the IN_PROGRESS. */
771
772         /* finally add the lockres to its hash bucket */
773         __dlm_insert_lockres(dlm, res);
774         /* get an extra ref on the mle in case this is a BLOCK
775          * if so, the creator of the BLOCK may try to put the last
776          * ref at this time in the assert master handler, so we
777          * need an extra one to keep from a bad ptr deref. */
778         dlm_get_mle(mle);
779         spin_unlock(&dlm->master_lock);
780         spin_unlock(&dlm->spinlock);
781
782         /* must wait for lock to be mastered elsewhere */
783         if (blocked)
784                 goto wait;
785
786 redo_request:
787         ret = -EINVAL;
788         dlm_node_iter_init(mle->vote_map, &iter);
789         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
790                 ret = dlm_do_master_request(mle, nodenum);
791                 if (ret < 0)
792                         mlog_errno(ret);
793                 if (mle->master != O2NM_MAX_NODES) {
794                         /* found a master ! */
795                         break;
796                 }
797         }
798
799 wait:
800         /* keep going until the response map includes all nodes */
801         ret = dlm_wait_for_lock_mastery(dlm, res, mle, &blocked);
802         if (ret < 0) {
803                 mlog(0, "%s:%.*s: node map changed, redo the "
804                      "master request now, blocked=%d\n",
805                      dlm->name, res->lockname.len,
806                      res->lockname.name, blocked);
807                 if (++tries > 20) {
808                         mlog(ML_ERROR, "%s:%.*s: spinning on "
809                              "dlm_wait_for_lock_mastery, blocked=%d\n", 
810                              dlm->name, res->lockname.len, 
811                              res->lockname.name, blocked);
812                         dlm_print_one_lock_resource(res);
813                         /* dlm_print_one_mle(mle); */
814                         tries = 0;
815                 }
816                 goto redo_request;
817         }
818
819         mlog(0, "lockres mastered by %u\n", res->owner);
820         /* make sure we never continue without this */
821         BUG_ON(res->owner == O2NM_MAX_NODES);
822
823         /* master is known, detach if not already detached */
824         dlm_mle_detach_hb_events(dlm, mle);
825         dlm_put_mle(mle);
826         /* put the extra ref */
827         dlm_put_mle(mle);
828
829 wake_waiters:
830         spin_lock(&res->spinlock);
831         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
832         spin_unlock(&res->spinlock);
833         wake_up(&res->wq);
834
835 leave:
836         /* need to free the unused mle */
837         if (alloc_mle)
838                 kmem_cache_free(dlm_mle_cache, alloc_mle);
839
840         return res;
841 }
842
843
844 #define DLM_MASTERY_TIMEOUT_MS   5000
845
846 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
847                                      struct dlm_lock_resource *res,
848                                      struct dlm_master_list_entry *mle,
849                                      int *blocked)
850 {
851         u8 m;
852         int ret, bit;
853         int map_changed, voting_done;
854         int assert, sleep;
855
856 recheck:
857         ret = 0;
858         assert = 0;
859
860         /* check if another node has already become the owner */
861         spin_lock(&res->spinlock);
862         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
863                 spin_unlock(&res->spinlock);
864                 goto leave;
865         }
866         spin_unlock(&res->spinlock);
867
868         spin_lock(&mle->spinlock);
869         m = mle->master;
870         map_changed = (memcmp(mle->vote_map, mle->node_map,
871                               sizeof(mle->vote_map)) != 0);
872         voting_done = (memcmp(mle->vote_map, mle->response_map,
873                              sizeof(mle->vote_map)) == 0);
874
875         /* restart if we hit any errors */
876         if (map_changed) {
877                 int b;
878                 mlog(0, "%s: %.*s: node map changed, restarting\n",
879                      dlm->name, res->lockname.len, res->lockname.name);
880                 ret = dlm_restart_lock_mastery(dlm, res, mle, *blocked);
881                 b = (mle->type == DLM_MLE_BLOCK);
882                 if ((*blocked && !b) || (!*blocked && b)) {
883                         mlog(0, "%s:%.*s: status change: old=%d new=%d\n", 
884                              dlm->name, res->lockname.len, res->lockname.name,
885                              *blocked, b);
886                         *blocked = b;
887                 }
888                 spin_unlock(&mle->spinlock);
889                 if (ret < 0) {
890                         mlog_errno(ret);
891                         goto leave;
892                 }
893                 mlog(0, "%s:%.*s: restart lock mastery succeeded, "
894                      "rechecking now\n", dlm->name, res->lockname.len,
895                      res->lockname.name);
896                 goto recheck;
897         }
898
899         if (m != O2NM_MAX_NODES) {
900                 /* another node has done an assert!
901                  * all done! */
902                 sleep = 0;
903         } else {
904                 sleep = 1;
905                 /* have all nodes responded? */
906                 if (voting_done && !*blocked) {
907                         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
908                         if (dlm->node_num <= bit) {
909                                 /* my node number is lowest.
910                                  * now tell other nodes that I am
911                                  * mastering this. */
912                                 mle->master = dlm->node_num;
913                                 assert = 1;
914                                 sleep = 0;
915                         }
916                         /* if voting is done, but we have not received
917                          * an assert master yet, we must sleep */
918                 }
919         }
920
921         spin_unlock(&mle->spinlock);
922
923         /* sleep if we haven't finished voting yet */
924         if (sleep) {
925                 unsigned long timeo = msecs_to_jiffies(DLM_MASTERY_TIMEOUT_MS);
926
927                 /*
928                 if (atomic_read(&mle->mle_refs.refcount) < 2)
929                         mlog(ML_ERROR, "mle (%p) refs=%d, name=%.*s\n", mle,
930                         atomic_read(&mle->mle_refs.refcount),
931                         res->lockname.len, res->lockname.name);
932                 */
933                 atomic_set(&mle->woken, 0);
934                 (void)wait_event_timeout(mle->wq,
935                                          (atomic_read(&mle->woken) == 1),
936                                          timeo);
937                 if (res->owner == O2NM_MAX_NODES) {
938                         mlog(0, "waiting again\n");
939                         goto recheck;
940                 }
941                 mlog(0, "done waiting, master is %u\n", res->owner);
942                 ret = 0;
943                 goto leave;
944         }
945
946         ret = 0;   /* done */
947         if (assert) {
948                 m = dlm->node_num;
949                 mlog(0, "about to master %.*s here, this=%u\n",
950                      res->lockname.len, res->lockname.name, m);
951                 ret = dlm_do_assert_master(dlm, res->lockname.name,
952                                            res->lockname.len, mle->vote_map, 0);
953                 if (ret) {
954                         /* This is a failure in the network path,
955                          * not in the response to the assert_master
956                          * (any nonzero response is a BUG on this node).
957                          * Most likely a socket just got disconnected
958                          * due to node death. */
959                         mlog_errno(ret);
960                 }
961                 /* no longer need to restart lock mastery.
962                  * all living nodes have been contacted. */
963                 ret = 0;
964         }
965
966         /* set the lockres owner */
967         spin_lock(&res->spinlock);
968         dlm_change_lockres_owner(dlm, res, m);
969         spin_unlock(&res->spinlock);
970
971 leave:
972         return ret;
973 }
974
975 struct dlm_bitmap_diff_iter
976 {
977         int curnode;
978         unsigned long *orig_bm;
979         unsigned long *cur_bm;
980         unsigned long diff_bm[BITS_TO_LONGS(O2NM_MAX_NODES)];
981 };
982
983 enum dlm_node_state_change
984 {
985         NODE_DOWN = -1,
986         NODE_NO_CHANGE = 0,
987         NODE_UP
988 };
989
990 static void dlm_bitmap_diff_iter_init(struct dlm_bitmap_diff_iter *iter,
991                                       unsigned long *orig_bm,
992                                       unsigned long *cur_bm)
993 {
994         unsigned long p1, p2;
995         int i;
996
997         iter->curnode = -1;
998         iter->orig_bm = orig_bm;
999         iter->cur_bm = cur_bm;
1000
1001         for (i = 0; i < BITS_TO_LONGS(O2NM_MAX_NODES); i++) {
1002                 p1 = *(iter->orig_bm + i);
1003                 p2 = *(iter->cur_bm + i);
1004                 iter->diff_bm[i] = (p1 & ~p2) | (p2 & ~p1);
1005         }
1006 }
1007
1008 static int dlm_bitmap_diff_iter_next(struct dlm_bitmap_diff_iter *iter,
1009                                      enum dlm_node_state_change *state)
1010 {
1011         int bit;
1012
1013         if (iter->curnode >= O2NM_MAX_NODES)
1014                 return -ENOENT;
1015
1016         bit = find_next_bit(iter->diff_bm, O2NM_MAX_NODES,
1017                             iter->curnode+1);
1018         if (bit >= O2NM_MAX_NODES) {
1019                 iter->curnode = O2NM_MAX_NODES;
1020                 return -ENOENT;
1021         }
1022
1023         /* if it was there in the original then this node died */
1024         if (test_bit(bit, iter->orig_bm))
1025                 *state = NODE_DOWN;
1026         else
1027                 *state = NODE_UP;
1028
1029         iter->curnode = bit;
1030         return bit;
1031 }
1032
1033
1034 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
1035                                     struct dlm_lock_resource *res,
1036                                     struct dlm_master_list_entry *mle,
1037                                     int blocked)
1038 {
1039         struct dlm_bitmap_diff_iter bdi;
1040         enum dlm_node_state_change sc;
1041         int node;
1042         int ret = 0;
1043
1044         mlog(0, "something happened such that the "
1045              "master process may need to be restarted!\n");
1046
1047         assert_spin_locked(&mle->spinlock);
1048
1049         dlm_bitmap_diff_iter_init(&bdi, mle->vote_map, mle->node_map);
1050         node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1051         while (node >= 0) {
1052                 if (sc == NODE_UP) {
1053                         /* a node came up.  clear any old vote from
1054                          * the response map and set it in the vote map
1055                          * then restart the mastery. */
1056                         mlog(ML_NOTICE, "node %d up while restarting\n", node);
1057
1058                         /* redo the master request, but only for the new node */
1059                         mlog(0, "sending request to new node\n");
1060                         clear_bit(node, mle->response_map);
1061                         set_bit(node, mle->vote_map);
1062                 } else {
1063                         mlog(ML_ERROR, "node down! %d\n", node);
1064
1065                         /* if the node wasn't involved in mastery skip it,
1066                          * but clear it out from the maps so that it will
1067                          * not affect mastery of this lockres */
1068                         clear_bit(node, mle->response_map);
1069                         clear_bit(node, mle->vote_map);
1070                         if (!test_bit(node, mle->maybe_map))
1071                                 goto next;
1072
1073                         /* if we're already blocked on lock mastery, and the
1074                          * dead node wasn't the expected master, or there is
1075                          * another node in the maybe_map, keep waiting */
1076                         if (blocked) {
1077                                 int lowest = find_next_bit(mle->maybe_map,
1078                                                        O2NM_MAX_NODES, 0);
1079
1080                                 /* act like it was never there */
1081                                 clear_bit(node, mle->maybe_map);
1082
1083                                 if (node != lowest)
1084                                         goto next;
1085
1086                                 mlog(ML_ERROR, "expected master %u died while "
1087                                      "this node was blocked waiting on it!\n",
1088                                      node);
1089                                 lowest = find_next_bit(mle->maybe_map,
1090                                                        O2NM_MAX_NODES,
1091                                                        lowest+1);
1092                                 if (lowest < O2NM_MAX_NODES) {
1093                                         mlog(0, "still blocked. waiting "
1094                                              "on %u now\n", lowest);
1095                                         goto next;
1096                                 }
1097
1098                                 /* mle is an MLE_BLOCK, but there is now
1099                                  * nothing left to block on.  we need to return
1100                                  * all the way back out and try again with
1101                                  * an MLE_MASTER. dlm_do_local_recovery_cleanup
1102                                  * has already run, so the mle refcount is ok */
1103                                 mlog(0, "no longer blocking. we can "
1104                                      "try to master this here\n");
1105                                 mle->type = DLM_MLE_MASTER;
1106                                 memset(mle->maybe_map, 0,
1107                                        sizeof(mle->maybe_map));
1108                                 memset(mle->response_map, 0,
1109                                        sizeof(mle->maybe_map));
1110                                 memcpy(mle->vote_map, mle->node_map,
1111                                        sizeof(mle->node_map));
1112                                 mle->u.res = res;
1113                                 set_bit(dlm->node_num, mle->maybe_map);
1114
1115                                 ret = -EAGAIN;
1116                                 goto next;
1117                         }
1118
1119                         clear_bit(node, mle->maybe_map);
1120                         if (node > dlm->node_num)
1121                                 goto next;
1122
1123                         mlog(0, "dead node in map!\n");
1124                         /* yuck. go back and re-contact all nodes
1125                          * in the vote_map, removing this node. */
1126                         memset(mle->response_map, 0,
1127                                sizeof(mle->response_map));
1128                 }
1129                 ret = -EAGAIN;
1130 next:
1131                 node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1132         }
1133         return ret;
1134 }
1135
1136
1137 /*
1138  * DLM_MASTER_REQUEST_MSG
1139  *
1140  * returns: 0 on success,
1141  *          -errno on a network error
1142  *
1143  * on error, the caller should assume the target node is "dead"
1144  *
1145  */
1146
1147 static int dlm_do_master_request(struct dlm_master_list_entry *mle, int to)
1148 {
1149         struct dlm_ctxt *dlm = mle->dlm;
1150         struct dlm_master_request request;
1151         int ret, response=0, resend;
1152
1153         memset(&request, 0, sizeof(request));
1154         request.node_idx = dlm->node_num;
1155
1156         BUG_ON(mle->type == DLM_MLE_MIGRATION);
1157
1158         if (mle->type != DLM_MLE_MASTER) {
1159                 request.namelen = mle->u.name.len;
1160                 memcpy(request.name, mle->u.name.name, request.namelen);
1161         } else {
1162                 request.namelen = mle->u.res->lockname.len;
1163                 memcpy(request.name, mle->u.res->lockname.name,
1164                         request.namelen);
1165         }
1166
1167 again:
1168         ret = o2net_send_message(DLM_MASTER_REQUEST_MSG, dlm->key, &request,
1169                                  sizeof(request), to, &response);
1170         if (ret < 0)  {
1171                 if (ret == -ESRCH) {
1172                         /* should never happen */
1173                         mlog(ML_ERROR, "TCP stack not ready!\n");
1174                         BUG();
1175                 } else if (ret == -EINVAL) {
1176                         mlog(ML_ERROR, "bad args passed to o2net!\n");
1177                         BUG();
1178                 } else if (ret == -ENOMEM) {
1179                         mlog(ML_ERROR, "out of memory while trying to send "
1180                              "network message!  retrying\n");
1181                         /* this is totally crude */
1182                         msleep(50);
1183                         goto again;
1184                 } else if (!dlm_is_host_down(ret)) {
1185                         /* not a network error. bad. */
1186                         mlog_errno(ret);
1187                         mlog(ML_ERROR, "unhandled error!");
1188                         BUG();
1189                 }
1190                 /* all other errors should be network errors,
1191                  * and likely indicate node death */
1192                 mlog(ML_ERROR, "link to %d went down!\n", to);
1193                 goto out;
1194         }
1195
1196         ret = 0;
1197         resend = 0;
1198         spin_lock(&mle->spinlock);
1199         switch (response) {
1200                 case DLM_MASTER_RESP_YES:
1201                         set_bit(to, mle->response_map);
1202                         mlog(0, "node %u is the master, response=YES\n", to);
1203                         mle->master = to;
1204                         break;
1205                 case DLM_MASTER_RESP_NO:
1206                         mlog(0, "node %u not master, response=NO\n", to);
1207                         set_bit(to, mle->response_map);
1208                         break;
1209                 case DLM_MASTER_RESP_MAYBE:
1210                         mlog(0, "node %u not master, response=MAYBE\n", to);
1211                         set_bit(to, mle->response_map);
1212                         set_bit(to, mle->maybe_map);
1213                         break;
1214                 case DLM_MASTER_RESP_ERROR:
1215                         mlog(0, "node %u hit an error, resending\n", to);
1216                         resend = 1;
1217                         response = 0;
1218                         break;
1219                 default:
1220                         mlog(ML_ERROR, "bad response! %u\n", response);
1221                         BUG();
1222         }
1223         spin_unlock(&mle->spinlock);
1224         if (resend) {
1225                 /* this is also totally crude */
1226                 msleep(50);
1227                 goto again;
1228         }
1229
1230 out:
1231         return ret;
1232 }
1233
1234 /*
1235  * locks that can be taken here:
1236  * dlm->spinlock
1237  * res->spinlock
1238  * mle->spinlock
1239  * dlm->master_list
1240  *
1241  * if possible, TRIM THIS DOWN!!!
1242  */
1243 int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data)
1244 {
1245         u8 response = DLM_MASTER_RESP_MAYBE;
1246         struct dlm_ctxt *dlm = data;
1247         struct dlm_lock_resource *res;
1248         struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
1249         struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
1250         char *name;
1251         unsigned int namelen;
1252         int found, ret;
1253         int set_maybe;
1254
1255         if (!dlm_grab(dlm))
1256                 return DLM_MASTER_RESP_NO;
1257
1258         if (!dlm_domain_fully_joined(dlm)) {
1259                 response = DLM_MASTER_RESP_NO;
1260                 goto send_response;
1261         }
1262
1263         name = request->name;
1264         namelen = request->namelen;
1265
1266         if (namelen > DLM_LOCKID_NAME_MAX) {
1267                 response = DLM_IVBUFLEN;
1268                 goto send_response;
1269         }
1270
1271 way_up_top:
1272         spin_lock(&dlm->spinlock);
1273         res = __dlm_lookup_lockres(dlm, name, namelen);
1274         if (res) {
1275                 spin_unlock(&dlm->spinlock);
1276
1277                 /* take care of the easy cases up front */
1278                 spin_lock(&res->spinlock);
1279                 if (res->state & DLM_LOCK_RES_RECOVERING) {
1280                         spin_unlock(&res->spinlock);
1281                         mlog(0, "returning DLM_MASTER_RESP_ERROR since res is "
1282                              "being recovered\n");
1283                         response = DLM_MASTER_RESP_ERROR;
1284                         if (mle)
1285                                 kmem_cache_free(dlm_mle_cache, mle);
1286                         goto send_response;
1287                 }
1288
1289                 if (res->owner == dlm->node_num) {
1290                         u32 flags = DLM_ASSERT_MASTER_MLE_CLEANUP;
1291                         spin_unlock(&res->spinlock);
1292                         // mlog(0, "this node is the master\n");
1293                         response = DLM_MASTER_RESP_YES;
1294                         if (mle)
1295                                 kmem_cache_free(dlm_mle_cache, mle);
1296
1297                         /* this node is the owner.
1298                          * there is some extra work that needs to
1299                          * happen now.  the requesting node has
1300                          * caused all nodes up to this one to
1301                          * create mles.  this node now needs to
1302                          * go back and clean those up. */
1303                         mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
1304                              dlm->node_num, res->lockname.len, res->lockname.name);
1305                         ret = dlm_dispatch_assert_master(dlm, res, 1,
1306                                                          request->node_idx,
1307                                                          flags);
1308                         if (ret < 0) {
1309                                 mlog(ML_ERROR, "failed to dispatch assert "
1310                                      "master work\n");
1311                                 response = DLM_MASTER_RESP_ERROR;
1312                         }
1313                         goto send_response;
1314                 } else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1315                         spin_unlock(&res->spinlock);
1316                         // mlog(0, "node %u is the master\n", res->owner);
1317                         response = DLM_MASTER_RESP_NO;
1318                         if (mle)
1319                                 kmem_cache_free(dlm_mle_cache, mle);
1320                         goto send_response;
1321                 }
1322
1323                 /* ok, there is no owner.  either this node is
1324                  * being blocked, or it is actively trying to
1325                  * master this lock. */
1326                 if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1327                         mlog(ML_ERROR, "lock with no owner should be "
1328                              "in-progress!\n");
1329                         BUG();
1330                 }
1331
1332                 // mlog(0, "lockres is in progress...\n");
1333                 spin_lock(&dlm->master_lock);
1334                 found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1335                 if (!found) {
1336                         mlog(ML_ERROR, "no mle found for this lock!\n");
1337                         BUG();
1338                 }
1339                 set_maybe = 1;
1340                 spin_lock(&tmpmle->spinlock);
1341                 if (tmpmle->type == DLM_MLE_BLOCK) {
1342                         // mlog(0, "this node is waiting for "
1343                         // "lockres to be mastered\n");
1344                         response = DLM_MASTER_RESP_NO;
1345                 } else if (tmpmle->type == DLM_MLE_MIGRATION) {
1346                         mlog(0, "node %u is master, but trying to migrate to "
1347                              "node %u.\n", tmpmle->master, tmpmle->new_master);
1348                         if (tmpmle->master == dlm->node_num) {
1349                                 response = DLM_MASTER_RESP_YES;
1350                                 mlog(ML_ERROR, "no owner on lockres, but this "
1351                                      "node is trying to migrate it to %u?!\n",
1352                                      tmpmle->new_master);
1353                                 BUG();
1354                         } else {
1355                                 /* the real master can respond on its own */
1356                                 response = DLM_MASTER_RESP_NO;
1357                         }
1358                 } else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
1359                         set_maybe = 0;
1360                         if (tmpmle->master == dlm->node_num)
1361                                 response = DLM_MASTER_RESP_YES;
1362                         else
1363                                 response = DLM_MASTER_RESP_NO;
1364                 } else {
1365                         // mlog(0, "this node is attempting to "
1366                         // "master lockres\n");
1367                         response = DLM_MASTER_RESP_MAYBE;
1368                 }
1369                 if (set_maybe)
1370                         set_bit(request->node_idx, tmpmle->maybe_map);
1371                 spin_unlock(&tmpmle->spinlock);
1372
1373                 spin_unlock(&dlm->master_lock);
1374                 spin_unlock(&res->spinlock);
1375
1376                 /* keep the mle attached to heartbeat events */
1377                 dlm_put_mle(tmpmle);
1378                 if (mle)
1379                         kmem_cache_free(dlm_mle_cache, mle);
1380                 goto send_response;
1381         }
1382
1383         /*
1384          * lockres doesn't exist on this node
1385          * if there is an MLE_BLOCK, return NO
1386          * if there is an MLE_MASTER, return MAYBE
1387          * otherwise, add an MLE_BLOCK, return NO
1388          */
1389         spin_lock(&dlm->master_lock);
1390         found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1391         if (!found) {
1392                 /* this lockid has never been seen on this node yet */
1393                 // mlog(0, "no mle found\n");
1394                 if (!mle) {
1395                         spin_unlock(&dlm->master_lock);
1396                         spin_unlock(&dlm->spinlock);
1397
1398                         mle = (struct dlm_master_list_entry *)
1399                                 kmem_cache_alloc(dlm_mle_cache, GFP_KERNEL);
1400                         if (!mle) {
1401                                 // bad bad bad... this sucks.
1402                                 response = DLM_MASTER_RESP_ERROR;
1403                                 goto send_response;
1404                         }
1405                         spin_lock(&dlm->spinlock);
1406                         dlm_init_mle(mle, DLM_MLE_BLOCK, dlm, NULL,
1407                                          name, namelen);
1408                         spin_unlock(&dlm->spinlock);
1409                         goto way_up_top;
1410                 }
1411
1412                 // mlog(0, "this is second time thru, already allocated, "
1413                 // "add the block.\n");
1414                 set_bit(request->node_idx, mle->maybe_map);
1415                 list_add(&mle->list, &dlm->master_list);
1416                 response = DLM_MASTER_RESP_NO;
1417         } else {
1418                 // mlog(0, "mle was found\n");
1419                 set_maybe = 1;
1420                 spin_lock(&tmpmle->spinlock);
1421                 if (tmpmle->type == DLM_MLE_BLOCK)
1422                         response = DLM_MASTER_RESP_NO;
1423                 else if (tmpmle->type == DLM_MLE_MIGRATION) {
1424                         mlog(0, "migration mle was found (%u->%u)\n",
1425                              tmpmle->master, tmpmle->new_master);
1426                         if (tmpmle->master == dlm->node_num) {
1427                                 mlog(ML_ERROR, "no lockres, but migration mle "
1428                                      "says that this node is master!\n");
1429                                 BUG();
1430                         }
1431                         /* real master can respond on its own */
1432                         response = DLM_MASTER_RESP_NO;
1433                 } else {
1434                         if (tmpmle->master == dlm->node_num) {
1435                                 response = DLM_MASTER_RESP_YES;
1436                                 set_maybe = 0;
1437                         } else
1438                                 response = DLM_MASTER_RESP_MAYBE;
1439                 }
1440                 if (set_maybe)
1441                         set_bit(request->node_idx, tmpmle->maybe_map);
1442                 spin_unlock(&tmpmle->spinlock);
1443         }
1444         spin_unlock(&dlm->master_lock);
1445         spin_unlock(&dlm->spinlock);
1446
1447         if (found) {
1448                 /* keep the mle attached to heartbeat events */
1449                 dlm_put_mle(tmpmle);
1450         }
1451 send_response:
1452         dlm_put(dlm);
1453         return response;
1454 }
1455
1456 /*
1457  * DLM_ASSERT_MASTER_MSG
1458  */
1459
1460
1461 /*
1462  * NOTE: this can be used for debugging
1463  * can periodically run all locks owned by this node
1464  * and re-assert across the cluster...
1465  */
1466 static int dlm_do_assert_master(struct dlm_ctxt *dlm, const char *lockname,
1467                                 unsigned int namelen, void *nodemap,
1468                                 u32 flags)
1469 {
1470         struct dlm_assert_master assert;
1471         int to, tmpret;
1472         struct dlm_node_iter iter;
1473         int ret = 0;
1474
1475         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
1476
1477         /* note that if this nodemap is empty, it returns 0 */
1478         dlm_node_iter_init(nodemap, &iter);
1479         while ((to = dlm_node_iter_next(&iter)) >= 0) {
1480                 int r = 0;
1481                 mlog(0, "sending assert master to %d (%.*s)\n", to,
1482                      namelen, lockname);
1483                 memset(&assert, 0, sizeof(assert));
1484                 assert.node_idx = dlm->node_num;
1485                 assert.namelen = namelen;
1486                 memcpy(assert.name, lockname, namelen);
1487                 assert.flags = cpu_to_be32(flags);
1488
1489                 tmpret = o2net_send_message(DLM_ASSERT_MASTER_MSG, dlm->key,
1490                                             &assert, sizeof(assert), to, &r);
1491                 if (tmpret < 0) {
1492                         mlog(ML_ERROR, "assert_master returned %d!\n", tmpret);
1493                         if (!dlm_is_host_down(tmpret)) {
1494                                 mlog(ML_ERROR, "unhandled error!\n");
1495                                 BUG();
1496                         }
1497                         /* a node died.  finish out the rest of the nodes. */
1498                         mlog(ML_ERROR, "link to %d went down!\n", to);
1499                         /* any nonzero status return will do */
1500                         ret = tmpret;
1501                 } else if (r < 0) {
1502                         /* ok, something horribly messed.  kill thyself. */
1503                         mlog(ML_ERROR,"during assert master of %.*s to %u, "
1504                              "got %d.\n", namelen, lockname, to, r);
1505                         dlm_dump_lock_resources(dlm);
1506                         BUG();
1507                 }
1508         }
1509
1510         return ret;
1511 }
1512
1513 /*
1514  * locks that can be taken here:
1515  * dlm->spinlock
1516  * res->spinlock
1517  * mle->spinlock
1518  * dlm->master_list
1519  *
1520  * if possible, TRIM THIS DOWN!!!
1521  */
1522 int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data)
1523 {
1524         struct dlm_ctxt *dlm = data;
1525         struct dlm_master_list_entry *mle = NULL;
1526         struct dlm_assert_master *assert = (struct dlm_assert_master *)msg->buf;
1527         struct dlm_lock_resource *res = NULL;
1528         char *name;
1529         unsigned int namelen;
1530         u32 flags;
1531
1532         if (!dlm_grab(dlm))
1533                 return 0;
1534
1535         name = assert->name;
1536         namelen = assert->namelen;
1537         flags = be32_to_cpu(assert->flags);
1538
1539         if (namelen > DLM_LOCKID_NAME_MAX) {
1540                 mlog(ML_ERROR, "Invalid name length!");
1541                 goto done;
1542         }
1543
1544         spin_lock(&dlm->spinlock);
1545
1546         if (flags)
1547                 mlog(0, "assert_master with flags: %u\n", flags);
1548
1549         /* find the MLE */
1550         spin_lock(&dlm->master_lock);
1551         if (!dlm_find_mle(dlm, &mle, name, namelen)) {
1552                 /* not an error, could be master just re-asserting */
1553                 mlog(0, "just got an assert_master from %u, but no "
1554                      "MLE for it! (%.*s)\n", assert->node_idx,
1555                      namelen, name);
1556         } else {
1557                 int bit = find_next_bit (mle->maybe_map, O2NM_MAX_NODES, 0);
1558                 if (bit >= O2NM_MAX_NODES) {
1559                         /* not necessarily an error, though less likely.
1560                          * could be master just re-asserting. */
1561                         mlog(ML_ERROR, "no bits set in the maybe_map, but %u "
1562                              "is asserting! (%.*s)\n", assert->node_idx,
1563                              namelen, name);
1564                 } else if (bit != assert->node_idx) {
1565                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1566                                 mlog(0, "master %u was found, %u should "
1567                                      "back off\n", assert->node_idx, bit);
1568                         } else {
1569                                 /* with the fix for bug 569, a higher node
1570                                  * number winning the mastery will respond
1571                                  * YES to mastery requests, but this node
1572                                  * had no way of knowing.  let it pass. */
1573                                 mlog(ML_ERROR, "%u is the lowest node, "
1574                                      "%u is asserting. (%.*s)  %u must "
1575                                      "have begun after %u won.\n", bit,
1576                                      assert->node_idx, namelen, name, bit,
1577                                      assert->node_idx);
1578                         }
1579                 }
1580         }
1581         spin_unlock(&dlm->master_lock);
1582
1583         /* ok everything checks out with the MLE
1584          * now check to see if there is a lockres */
1585         res = __dlm_lookup_lockres(dlm, name, namelen);
1586         if (res) {
1587                 spin_lock(&res->spinlock);
1588                 if (res->state & DLM_LOCK_RES_RECOVERING)  {
1589                         mlog(ML_ERROR, "%u asserting but %.*s is "
1590                              "RECOVERING!\n", assert->node_idx, namelen, name);
1591                         goto kill;
1592                 }
1593                 if (!mle) {
1594                         if (res->owner != assert->node_idx) {
1595                                 mlog(ML_ERROR, "assert_master from "
1596                                           "%u, but current owner is "
1597                                           "%u! (%.*s)\n",
1598                                        assert->node_idx, res->owner,
1599                                        namelen, name);
1600                                 goto kill;
1601                         }
1602                 } else if (mle->type != DLM_MLE_MIGRATION) {
1603                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1604                                 /* owner is just re-asserting */
1605                                 if (res->owner == assert->node_idx) {
1606                                         mlog(0, "owner %u re-asserting on "
1607                                              "lock %.*s\n", assert->node_idx,
1608                                              namelen, name);
1609                                         goto ok;
1610                                 }
1611                                 mlog(ML_ERROR, "got assert_master from "
1612                                      "node %u, but %u is the owner! "
1613                                      "(%.*s)\n", assert->node_idx,
1614                                      res->owner, namelen, name);
1615                                 goto kill;
1616                         }
1617                         if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1618                                 mlog(ML_ERROR, "got assert from %u, but lock "
1619                                      "with no owner should be "
1620                                      "in-progress! (%.*s)\n",
1621                                      assert->node_idx,
1622                                      namelen, name);
1623                                 goto kill;
1624                         }
1625                 } else /* mle->type == DLM_MLE_MIGRATION */ {
1626                         /* should only be getting an assert from new master */
1627                         if (assert->node_idx != mle->new_master) {
1628                                 mlog(ML_ERROR, "got assert from %u, but "
1629                                      "new master is %u, and old master "
1630                                      "was %u (%.*s)\n",
1631                                      assert->node_idx, mle->new_master,
1632                                      mle->master, namelen, name);
1633                                 goto kill;
1634                         }
1635
1636                 }
1637 ok:
1638                 spin_unlock(&res->spinlock);
1639         }
1640         spin_unlock(&dlm->spinlock);
1641
1642         // mlog(0, "woo!  got an assert_master from node %u!\n",
1643         //           assert->node_idx);
1644         if (mle) {
1645                 int extra_ref;
1646                 
1647                 spin_lock(&mle->spinlock);
1648                 extra_ref = !!(mle->type == DLM_MLE_BLOCK
1649                                || mle->type == DLM_MLE_MIGRATION);
1650                 mle->master = assert->node_idx;
1651                 atomic_set(&mle->woken, 1);
1652                 wake_up(&mle->wq);
1653                 spin_unlock(&mle->spinlock);
1654
1655                 if (mle->type == DLM_MLE_MIGRATION && res) {
1656                         mlog(0, "finishing off migration of lockres %.*s, "
1657                              "from %u to %u\n",
1658                                res->lockname.len, res->lockname.name,
1659                                dlm->node_num, mle->new_master);
1660                         spin_lock(&res->spinlock);
1661                         res->state &= ~DLM_LOCK_RES_MIGRATING;
1662                         dlm_change_lockres_owner(dlm, res, mle->new_master);
1663                         BUG_ON(res->state & DLM_LOCK_RES_DIRTY);
1664                         spin_unlock(&res->spinlock);
1665                 }
1666                 /* master is known, detach if not already detached */
1667                 dlm_mle_detach_hb_events(dlm, mle);
1668                 dlm_put_mle(mle);
1669                 
1670                 if (extra_ref) {
1671                         /* the assert master message now balances the extra
1672                          * ref given by the master / migration request message.
1673                          * if this is the last put, it will be removed
1674                          * from the list. */
1675                         dlm_put_mle(mle);
1676                 }
1677         }
1678
1679 done:
1680         if (res)
1681                 dlm_lockres_put(res);
1682         dlm_put(dlm);
1683         return 0;
1684
1685 kill:
1686         /* kill the caller! */
1687         spin_unlock(&res->spinlock);
1688         spin_unlock(&dlm->spinlock);
1689         dlm_lockres_put(res);
1690         mlog(ML_ERROR, "Bad message received from another node.  Dumping state "
1691              "and killing the other node now!  This node is OK and can continue.\n");
1692         dlm_dump_lock_resources(dlm);
1693         dlm_put(dlm);
1694         return -EINVAL;
1695 }
1696
1697 int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
1698                                struct dlm_lock_resource *res,
1699                                int ignore_higher, u8 request_from, u32 flags)
1700 {
1701         struct dlm_work_item *item;
1702         item = kcalloc(1, sizeof(*item), GFP_KERNEL);
1703         if (!item)
1704                 return -ENOMEM;
1705
1706
1707         /* queue up work for dlm_assert_master_worker */
1708         dlm_grab(dlm);  /* get an extra ref for the work item */
1709         dlm_init_work_item(dlm, item, dlm_assert_master_worker, NULL);
1710         item->u.am.lockres = res; /* already have a ref */
1711         /* can optionally ignore node numbers higher than this node */
1712         item->u.am.ignore_higher = ignore_higher;
1713         item->u.am.request_from = request_from;
1714         item->u.am.flags = flags;
1715
1716         spin_lock(&dlm->work_lock);
1717         list_add_tail(&item->list, &dlm->work_list);
1718         spin_unlock(&dlm->work_lock);
1719
1720         schedule_work(&dlm->dispatched_work);
1721         return 0;
1722 }
1723
1724 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
1725 {
1726         struct dlm_ctxt *dlm = data;
1727         int ret = 0;
1728         struct dlm_lock_resource *res;
1729         unsigned long nodemap[BITS_TO_LONGS(O2NM_MAX_NODES)];
1730         int ignore_higher;
1731         int bit;
1732         u8 request_from;
1733         u32 flags;
1734
1735         dlm = item->dlm;
1736         res = item->u.am.lockres;
1737         ignore_higher = item->u.am.ignore_higher;
1738         request_from = item->u.am.request_from;
1739         flags = item->u.am.flags;
1740
1741         spin_lock(&dlm->spinlock);
1742         memcpy(nodemap, dlm->domain_map, sizeof(nodemap));
1743         spin_unlock(&dlm->spinlock);
1744
1745         clear_bit(dlm->node_num, nodemap);
1746         if (ignore_higher) {
1747                 /* if is this just to clear up mles for nodes below
1748                  * this node, do not send the message to the original
1749                  * caller or any node number higher than this */
1750                 clear_bit(request_from, nodemap);
1751                 bit = dlm->node_num;
1752                 while (1) {
1753                         bit = find_next_bit(nodemap, O2NM_MAX_NODES,
1754                                             bit+1);
1755                         if (bit >= O2NM_MAX_NODES)
1756                                 break;
1757                         clear_bit(bit, nodemap);
1758                 }
1759         }
1760
1761         /* this call now finishes out the nodemap
1762          * even if one or more nodes die */
1763         mlog(0, "worker about to master %.*s here, this=%u\n",
1764                      res->lockname.len, res->lockname.name, dlm->node_num);
1765         ret = dlm_do_assert_master(dlm, res->lockname.name,
1766                                    res->lockname.len,
1767                                    nodemap, flags);
1768         if (ret < 0) {
1769                 /* no need to restart, we are done */
1770                 mlog_errno(ret);
1771         }
1772
1773         dlm_lockres_put(res);
1774
1775         mlog(0, "finished with dlm_assert_master_worker\n");
1776 }
1777
1778
1779 /*
1780  * DLM_MIGRATE_LOCKRES
1781  */
1782
1783
1784 int dlm_migrate_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
1785                         u8 target)
1786 {
1787         struct dlm_master_list_entry *mle = NULL;
1788         struct dlm_master_list_entry *oldmle = NULL;
1789         struct dlm_migratable_lockres *mres = NULL;
1790         int ret = -EINVAL;
1791         const char *name;
1792         unsigned int namelen;
1793         int mle_added = 0;
1794         struct list_head *queue, *iter;
1795         int i;
1796         struct dlm_lock *lock;
1797         int empty = 1;
1798
1799         if (!dlm_grab(dlm))
1800                 return -EINVAL;
1801
1802         name = res->lockname.name;
1803         namelen = res->lockname.len;
1804
1805         mlog(0, "migrating %.*s to %u\n", namelen, name, target);
1806
1807         /*
1808          * ensure this lockres is a proper candidate for migration
1809          */
1810         spin_lock(&res->spinlock);
1811         if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
1812                 mlog(0, "cannot migrate lockres with unknown owner!\n");
1813                 spin_unlock(&res->spinlock);
1814                 goto leave;
1815         }
1816         if (res->owner != dlm->node_num) {
1817                 mlog(0, "cannot migrate lockres this node doesn't own!\n");
1818                 spin_unlock(&res->spinlock);
1819                 goto leave;
1820         }
1821         mlog(0, "checking queues...\n");
1822         queue = &res->granted;
1823         for (i=0; i<3; i++) {
1824                 list_for_each(iter, queue) {
1825                         lock = list_entry (iter, struct dlm_lock, list);
1826                         empty = 0;
1827                         if (lock->ml.node == dlm->node_num) {
1828                                 mlog(0, "found a lock owned by this node "
1829                                      "still on the %s queue!  will not "
1830                                      "migrate this lockres\n",
1831                                      i==0 ? "granted" :
1832                                      (i==1 ? "converting" : "blocked"));
1833                                 spin_unlock(&res->spinlock);
1834                                 ret = -ENOTEMPTY;
1835                                 goto leave;
1836                         }
1837                 }
1838                 queue++;
1839         }
1840         mlog(0, "all locks on this lockres are nonlocal.  continuing\n");
1841         spin_unlock(&res->spinlock);
1842
1843         /* no work to do */
1844         if (empty) {
1845                 mlog(0, "no locks were found on this lockres! done!\n");
1846                 ret = 0;
1847                 goto leave;
1848         }
1849
1850         /*
1851          * preallocate up front
1852          * if this fails, abort
1853          */
1854
1855         ret = -ENOMEM;
1856         mres = (struct dlm_migratable_lockres *) __get_free_page(GFP_KERNEL);
1857         if (!mres) {
1858                 mlog_errno(ret);
1859                 goto leave;
1860         }
1861
1862         mle = (struct dlm_master_list_entry *) kmem_cache_alloc(dlm_mle_cache,
1863                                                                 GFP_KERNEL);
1864         if (!mle) {
1865                 mlog_errno(ret);
1866                 goto leave;
1867         }
1868         ret = 0;
1869
1870         /*
1871          * find a node to migrate the lockres to
1872          */
1873
1874         mlog(0, "picking a migration node\n");
1875         spin_lock(&dlm->spinlock);
1876         /* pick a new node */
1877         if (!test_bit(target, dlm->domain_map) ||
1878             target >= O2NM_MAX_NODES) {
1879                 target = dlm_pick_migration_target(dlm, res);
1880         }
1881         mlog(0, "node %u chosen for migration\n", target);
1882
1883         if (target >= O2NM_MAX_NODES ||
1884             !test_bit(target, dlm->domain_map)) {
1885                 /* target chosen is not alive */
1886                 ret = -EINVAL;
1887         }
1888
1889         if (ret) {
1890                 spin_unlock(&dlm->spinlock);
1891                 goto fail;
1892         }
1893
1894         mlog(0, "continuing with target = %u\n", target);
1895
1896         /*
1897          * clear any existing master requests and
1898          * add the migration mle to the list
1899          */
1900         spin_lock(&dlm->master_lock);
1901         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
1902                                     namelen, target, dlm->node_num);
1903         spin_unlock(&dlm->master_lock);
1904         spin_unlock(&dlm->spinlock);
1905
1906         if (ret == -EEXIST) {
1907                 mlog(0, "another process is already migrating it\n");
1908                 goto fail;
1909         }
1910         mle_added = 1;
1911
1912         /*
1913          * set the MIGRATING flag and flush asts
1914          * if we fail after this we need to re-dirty the lockres
1915          */
1916         if (dlm_mark_lockres_migrating(dlm, res, target) < 0) {
1917                 mlog(ML_ERROR, "tried to migrate %.*s to %u, but "
1918                      "the target went down.\n", res->lockname.len,
1919                      res->lockname.name, target);
1920                 spin_lock(&res->spinlock);
1921                 res->state &= ~DLM_LOCK_RES_MIGRATING;
1922                 spin_unlock(&res->spinlock);
1923                 ret = -EINVAL;
1924         }
1925
1926 fail:
1927         if (oldmle) {
1928                 /* master is known, detach if not already detached */
1929                 dlm_mle_detach_hb_events(dlm, oldmle);
1930                 dlm_put_mle(oldmle);
1931         }
1932
1933         if (ret < 0) {
1934                 if (mle_added) {
1935                         dlm_mle_detach_hb_events(dlm, mle);
1936                         dlm_put_mle(mle);
1937                 } else if (mle) {
1938                         kmem_cache_free(dlm_mle_cache, mle);
1939                 }
1940                 goto leave;
1941         }
1942
1943         /*
1944          * at this point, we have a migration target, an mle
1945          * in the master list, and the MIGRATING flag set on
1946          * the lockres
1947          */
1948
1949
1950         /* get an extra reference on the mle.
1951          * otherwise the assert_master from the new
1952          * master will destroy this.
1953          * also, make sure that all callers of dlm_get_mle
1954          * take both dlm->spinlock and dlm->master_lock */
1955         spin_lock(&dlm->spinlock);
1956         spin_lock(&dlm->master_lock);
1957         dlm_get_mle(mle);
1958         spin_unlock(&dlm->master_lock);
1959         spin_unlock(&dlm->spinlock);
1960
1961         /* notify new node and send all lock state */
1962         /* call send_one_lockres with migration flag.
1963          * this serves as notice to the target node that a
1964          * migration is starting. */
1965         ret = dlm_send_one_lockres(dlm, res, mres, target,
1966                                    DLM_MRES_MIGRATION);
1967
1968         if (ret < 0) {
1969                 mlog(0, "migration to node %u failed with %d\n",
1970                      target, ret);
1971                 /* migration failed, detach and clean up mle */
1972                 dlm_mle_detach_hb_events(dlm, mle);
1973                 dlm_put_mle(mle);
1974                 dlm_put_mle(mle);
1975                 goto leave;
1976         }
1977
1978         /* at this point, the target sends a message to all nodes,
1979          * (using dlm_do_migrate_request).  this node is skipped since
1980          * we had to put an mle in the list to begin the process.  this
1981          * node now waits for target to do an assert master.  this node
1982          * will be the last one notified, ensuring that the migration
1983          * is complete everywhere.  if the target dies while this is
1984          * going on, some nodes could potentially see the target as the
1985          * master, so it is important that my recovery finds the migration
1986          * mle and sets the master to UNKNONWN. */
1987
1988
1989         /* wait for new node to assert master */
1990         while (1) {
1991                 ret = wait_event_interruptible_timeout(mle->wq,
1992                                         (atomic_read(&mle->woken) == 1),
1993                                         msecs_to_jiffies(5000));
1994
1995                 if (ret >= 0) {
1996                         if (atomic_read(&mle->woken) == 1 ||
1997                             res->owner == target)
1998                                 break;
1999
2000                         mlog(0, "timed out during migration\n");
2001                         /* avoid hang during shutdown when migrating lockres 
2002                          * to a node which also goes down */
2003                         if (dlm_is_node_dead(dlm, target)) {
2004                                 mlog(0, "%s:%.*s: expected migration target %u "
2005                                      "is no longer up.  restarting.\n",
2006                                      dlm->name, res->lockname.len,
2007                                      res->lockname.name, target);
2008                                 ret = -ERESTARTSYS;
2009                         }
2010                 }
2011                 if (ret == -ERESTARTSYS) {
2012                         /* migration failed, detach and clean up mle */
2013                         dlm_mle_detach_hb_events(dlm, mle);
2014                         dlm_put_mle(mle);
2015                         dlm_put_mle(mle);
2016                         goto leave;
2017                 }
2018                 /* TODO: if node died: stop, clean up, return error */
2019         }
2020
2021         /* all done, set the owner, clear the flag */
2022         spin_lock(&res->spinlock);
2023         dlm_set_lockres_owner(dlm, res, target);
2024         res->state &= ~DLM_LOCK_RES_MIGRATING;
2025         dlm_remove_nonlocal_locks(dlm, res);
2026         spin_unlock(&res->spinlock);
2027         wake_up(&res->wq);
2028
2029         /* master is known, detach if not already detached */
2030         dlm_mle_detach_hb_events(dlm, mle);
2031         dlm_put_mle(mle);
2032         ret = 0;
2033
2034         dlm_lockres_calc_usage(dlm, res);
2035
2036 leave:
2037         /* re-dirty the lockres if we failed */
2038         if (ret < 0)
2039                 dlm_kick_thread(dlm, res);
2040
2041         /* TODO: cleanup */
2042         if (mres)
2043                 free_page((unsigned long)mres);
2044
2045         dlm_put(dlm);
2046
2047         mlog(0, "returning %d\n", ret);
2048         return ret;
2049 }
2050 EXPORT_SYMBOL_GPL(dlm_migrate_lockres);
2051
2052 int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock)
2053 {
2054         int ret;
2055         spin_lock(&dlm->ast_lock);
2056         spin_lock(&lock->spinlock);
2057         ret = (list_empty(&lock->bast_list) && !lock->bast_pending);
2058         spin_unlock(&lock->spinlock);
2059         spin_unlock(&dlm->ast_lock);
2060         return ret;
2061 }
2062
2063 static int dlm_migration_can_proceed(struct dlm_ctxt *dlm,
2064                                      struct dlm_lock_resource *res,
2065                                      u8 mig_target)
2066 {
2067         int can_proceed;
2068         spin_lock(&res->spinlock);
2069         can_proceed = !!(res->state & DLM_LOCK_RES_MIGRATING);
2070         spin_unlock(&res->spinlock);
2071
2072         /* target has died, so make the caller break out of the 
2073          * wait_event, but caller must recheck the domain_map */
2074         spin_lock(&dlm->spinlock);
2075         if (!test_bit(mig_target, dlm->domain_map))
2076                 can_proceed = 1;
2077         spin_unlock(&dlm->spinlock);
2078         return can_proceed;
2079 }
2080
2081 int dlm_lockres_is_dirty(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
2082 {
2083         int ret;
2084         spin_lock(&res->spinlock);
2085         ret = !!(res->state & DLM_LOCK_RES_DIRTY);
2086         spin_unlock(&res->spinlock);
2087         return ret;
2088 }
2089
2090
2091 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
2092                                        struct dlm_lock_resource *res,
2093                                        u8 target)
2094 {
2095         int ret = 0;
2096
2097         mlog(0, "dlm_mark_lockres_migrating: %.*s, from %u to %u\n",
2098                res->lockname.len, res->lockname.name, dlm->node_num,
2099                target);
2100         /* need to set MIGRATING flag on lockres.  this is done by
2101          * ensuring that all asts have been flushed for this lockres. */
2102         spin_lock(&res->spinlock);
2103         BUG_ON(res->migration_pending);
2104         res->migration_pending = 1;
2105         /* strategy is to reserve an extra ast then release
2106          * it below, letting the release do all of the work */
2107         __dlm_lockres_reserve_ast(res);
2108         spin_unlock(&res->spinlock);
2109
2110         /* now flush all the pending asts.. hang out for a bit */
2111         dlm_kick_thread(dlm, res);
2112         wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
2113         dlm_lockres_release_ast(dlm, res);
2114
2115         mlog(0, "about to wait on migration_wq, dirty=%s\n",
2116                res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
2117         /* if the extra ref we just put was the final one, this
2118          * will pass thru immediately.  otherwise, we need to wait
2119          * for the last ast to finish. */
2120 again:
2121         ret = wait_event_interruptible_timeout(dlm->migration_wq,
2122                    dlm_migration_can_proceed(dlm, res, target),
2123                    msecs_to_jiffies(1000));
2124         if (ret < 0) {
2125                 mlog(0, "woken again: migrating? %s, dead? %s\n",
2126                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2127                        test_bit(target, dlm->domain_map) ? "no":"yes");
2128         } else {
2129                 mlog(0, "all is well: migrating? %s, dead? %s\n",
2130                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2131                        test_bit(target, dlm->domain_map) ? "no":"yes");
2132         }
2133         if (!dlm_migration_can_proceed(dlm, res, target)) {
2134                 mlog(0, "trying again...\n");
2135                 goto again;
2136         }
2137
2138         /* did the target go down or die? */
2139         spin_lock(&dlm->spinlock);
2140         if (!test_bit(target, dlm->domain_map)) {
2141                 mlog(ML_ERROR, "aha. migration target %u just went down\n",
2142                      target);
2143                 ret = -EHOSTDOWN;
2144         }
2145         spin_unlock(&dlm->spinlock);
2146
2147         /*
2148          * at this point:
2149          *
2150          *   o the DLM_LOCK_RES_MIGRATING flag is set
2151          *   o there are no pending asts on this lockres
2152          *   o all processes trying to reserve an ast on this
2153          *     lockres must wait for the MIGRATING flag to clear
2154          */
2155         return ret;
2156 }
2157
2158 /* last step in the migration process.
2159  * original master calls this to free all of the dlm_lock
2160  * structures that used to be for other nodes. */
2161 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
2162                                       struct dlm_lock_resource *res)
2163 {
2164         struct list_head *iter, *iter2;
2165         struct list_head *queue = &res->granted;
2166         int i;
2167         struct dlm_lock *lock;
2168
2169         assert_spin_locked(&res->spinlock);
2170
2171         BUG_ON(res->owner == dlm->node_num);
2172
2173         for (i=0; i<3; i++) {
2174                 list_for_each_safe(iter, iter2, queue) {
2175                         lock = list_entry (iter, struct dlm_lock, list);
2176                         if (lock->ml.node != dlm->node_num) {
2177                                 mlog(0, "putting lock for node %u\n",
2178                                      lock->ml.node);
2179                                 /* be extra careful */
2180                                 BUG_ON(!list_empty(&lock->ast_list));
2181                                 BUG_ON(!list_empty(&lock->bast_list));
2182                                 BUG_ON(lock->ast_pending);
2183                                 BUG_ON(lock->bast_pending);
2184                                 list_del_init(&lock->list);
2185                                 dlm_lock_put(lock);
2186                         }
2187                 }
2188                 queue++;
2189         }
2190 }
2191
2192 /* for now this is not too intelligent.  we will
2193  * need stats to make this do the right thing.
2194  * this just finds the first lock on one of the
2195  * queues and uses that node as the target. */
2196 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
2197                                     struct dlm_lock_resource *res)
2198 {
2199         int i;
2200         struct list_head *queue = &res->granted;
2201         struct list_head *iter;
2202         struct dlm_lock *lock;
2203         int nodenum;
2204
2205         assert_spin_locked(&dlm->spinlock);
2206
2207         spin_lock(&res->spinlock);
2208         for (i=0; i<3; i++) {
2209                 list_for_each(iter, queue) {
2210                         /* up to the caller to make sure this node
2211                          * is alive */
2212                         lock = list_entry (iter, struct dlm_lock, list);
2213                         if (lock->ml.node != dlm->node_num) {
2214                                 spin_unlock(&res->spinlock);
2215                                 return lock->ml.node;
2216                         }
2217                 }
2218                 queue++;
2219         }
2220         spin_unlock(&res->spinlock);
2221         mlog(0, "have not found a suitable target yet! checking domain map\n");
2222
2223         /* ok now we're getting desperate.  pick anyone alive. */
2224         nodenum = -1;
2225         while (1) {
2226                 nodenum = find_next_bit(dlm->domain_map,
2227                                         O2NM_MAX_NODES, nodenum+1);
2228                 mlog(0, "found %d in domain map\n", nodenum);
2229                 if (nodenum >= O2NM_MAX_NODES)
2230                         break;
2231                 if (nodenum != dlm->node_num) {
2232                         mlog(0, "picking %d\n", nodenum);
2233                         return nodenum;
2234                 }
2235         }
2236
2237         mlog(0, "giving up.  no master to migrate to\n");
2238         return DLM_LOCK_RES_OWNER_UNKNOWN;
2239 }
2240
2241
2242
2243 /* this is called by the new master once all lockres
2244  * data has been received */
2245 static int dlm_do_migrate_request(struct dlm_ctxt *dlm,
2246                                   struct dlm_lock_resource *res,
2247                                   u8 master, u8 new_master,
2248                                   struct dlm_node_iter *iter)
2249 {
2250         struct dlm_migrate_request migrate;
2251         int ret, status = 0;
2252         int nodenum;
2253
2254         memset(&migrate, 0, sizeof(migrate));
2255         migrate.namelen = res->lockname.len;
2256         memcpy(migrate.name, res->lockname.name, migrate.namelen);
2257         migrate.new_master = new_master;
2258         migrate.master = master;
2259
2260         ret = 0;
2261
2262         /* send message to all nodes, except the master and myself */
2263         while ((nodenum = dlm_node_iter_next(iter)) >= 0) {
2264                 if (nodenum == master ||
2265                     nodenum == new_master)
2266                         continue;
2267
2268                 ret = o2net_send_message(DLM_MIGRATE_REQUEST_MSG, dlm->key,
2269                                          &migrate, sizeof(migrate), nodenum,
2270                                          &status);
2271                 if (ret < 0)
2272                         mlog_errno(ret);
2273                 else if (status < 0) {
2274                         mlog(0, "migrate request (node %u) returned %d!\n",
2275                              nodenum, status);
2276                         ret = status;
2277                 }
2278         }
2279
2280         if (ret < 0)
2281                 mlog_errno(ret);
2282
2283         mlog(0, "returning ret=%d\n", ret);
2284         return ret;
2285 }
2286
2287
2288 /* if there is an existing mle for this lockres, we now know who the master is.
2289  * (the one who sent us *this* message) we can clear it up right away.
2290  * since the process that put the mle on the list still has a reference to it,
2291  * we can unhash it now, set the master and wake the process.  as a result,
2292  * we will have no mle in the list to start with.  now we can add an mle for
2293  * the migration and this should be the only one found for those scanning the
2294  * list.  */
2295 int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data)
2296 {
2297         struct dlm_ctxt *dlm = data;
2298         struct dlm_lock_resource *res = NULL;
2299         struct dlm_migrate_request *migrate = (struct dlm_migrate_request *) msg->buf;
2300         struct dlm_master_list_entry *mle = NULL, *oldmle = NULL;
2301         const char *name;
2302         unsigned int namelen;
2303         int ret = 0;
2304
2305         if (!dlm_grab(dlm))
2306                 return -EINVAL;
2307
2308         name = migrate->name;
2309         namelen = migrate->namelen;
2310
2311         /* preallocate.. if this fails, abort */
2312         mle = (struct dlm_master_list_entry *) kmem_cache_alloc(dlm_mle_cache,
2313                                                          GFP_KERNEL);
2314
2315         if (!mle) {
2316                 ret = -ENOMEM;
2317                 goto leave;
2318         }
2319
2320         /* check for pre-existing lock */
2321         spin_lock(&dlm->spinlock);
2322         res = __dlm_lookup_lockres(dlm, name, namelen);
2323         spin_lock(&dlm->master_lock);
2324
2325         if (res) {
2326                 spin_lock(&res->spinlock);
2327                 if (res->state & DLM_LOCK_RES_RECOVERING) {
2328                         /* if all is working ok, this can only mean that we got
2329                         * a migrate request from a node that we now see as
2330                         * dead.  what can we do here?  drop it to the floor? */
2331                         spin_unlock(&res->spinlock);
2332                         mlog(ML_ERROR, "Got a migrate request, but the "
2333                              "lockres is marked as recovering!");
2334                         kmem_cache_free(dlm_mle_cache, mle);
2335                         ret = -EINVAL; /* need a better solution */
2336                         goto unlock;
2337                 }
2338                 res->state |= DLM_LOCK_RES_MIGRATING;
2339                 spin_unlock(&res->spinlock);
2340         }
2341
2342         /* ignore status.  only nonzero status would BUG. */
2343         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
2344                                     name, namelen,
2345                                     migrate->new_master,
2346                                     migrate->master);
2347
2348 unlock:
2349         spin_unlock(&dlm->master_lock);
2350         spin_unlock(&dlm->spinlock);
2351
2352         if (oldmle) {
2353                 /* master is known, detach if not already detached */
2354                 dlm_mle_detach_hb_events(dlm, oldmle);
2355                 dlm_put_mle(oldmle);
2356         }
2357
2358         if (res)
2359                 dlm_lockres_put(res);
2360 leave:
2361         dlm_put(dlm);
2362         return ret;
2363 }
2364
2365 /* must be holding dlm->spinlock and dlm->master_lock
2366  * when adding a migration mle, we can clear any other mles
2367  * in the master list because we know with certainty that
2368  * the master is "master".  so we remove any old mle from
2369  * the list after setting it's master field, and then add
2370  * the new migration mle.  this way we can hold with the rule
2371  * of having only one mle for a given lock name at all times. */
2372 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
2373                                  struct dlm_lock_resource *res,
2374                                  struct dlm_master_list_entry *mle,
2375                                  struct dlm_master_list_entry **oldmle,
2376                                  const char *name, unsigned int namelen,
2377                                  u8 new_master, u8 master)
2378 {
2379         int found;
2380         int ret = 0;
2381
2382         *oldmle = NULL;
2383
2384         mlog_entry_void();
2385
2386         assert_spin_locked(&dlm->spinlock);
2387         assert_spin_locked(&dlm->master_lock);
2388
2389         /* caller is responsible for any ref taken here on oldmle */
2390         found = dlm_find_mle(dlm, oldmle, (char *)name, namelen);
2391         if (found) {
2392                 struct dlm_master_list_entry *tmp = *oldmle;
2393                 spin_lock(&tmp->spinlock);
2394                 if (tmp->type == DLM_MLE_MIGRATION) {
2395                         if (master == dlm->node_num) {
2396                                 /* ah another process raced me to it */
2397                                 mlog(0, "tried to migrate %.*s, but some "
2398                                      "process beat me to it\n",
2399                                      namelen, name);
2400                                 ret = -EEXIST;
2401                         } else {
2402                                 /* bad.  2 NODES are trying to migrate! */
2403                                 mlog(ML_ERROR, "migration error  mle: "
2404                                      "master=%u new_master=%u // request: "
2405                                      "master=%u new_master=%u // "
2406                                      "lockres=%.*s\n",
2407                                      tmp->master, tmp->new_master,
2408                                      master, new_master,
2409                                      namelen, name);
2410                                 BUG();
2411                         }
2412                 } else {
2413                         /* this is essentially what assert_master does */
2414                         tmp->master = master;
2415                         atomic_set(&tmp->woken, 1);
2416                         wake_up(&tmp->wq);
2417                         /* remove it from the list so that only one
2418                          * mle will be found */
2419                         list_del_init(&tmp->list);
2420                 }
2421                 spin_unlock(&tmp->spinlock);
2422         }
2423
2424         /* now add a migration mle to the tail of the list */
2425         dlm_init_mle(mle, DLM_MLE_MIGRATION, dlm, res, name, namelen);
2426         mle->new_master = new_master;
2427         mle->master = master;
2428         /* do this for consistency with other mle types */
2429         set_bit(new_master, mle->maybe_map);
2430         list_add(&mle->list, &dlm->master_list);
2431
2432         return ret;
2433 }
2434
2435
2436 void dlm_clean_master_list(struct dlm_ctxt *dlm, u8 dead_node)
2437 {
2438         struct list_head *iter, *iter2;
2439         struct dlm_master_list_entry *mle;
2440         struct dlm_lock_resource *res;
2441
2442         mlog_entry("dlm=%s, dead node=%u\n", dlm->name, dead_node);
2443 top:
2444         assert_spin_locked(&dlm->spinlock);
2445
2446         /* clean the master list */
2447         spin_lock(&dlm->master_lock);
2448         list_for_each_safe(iter, iter2, &dlm->master_list) {
2449                 mle = list_entry(iter, struct dlm_master_list_entry, list);
2450
2451                 BUG_ON(mle->type != DLM_MLE_BLOCK &&
2452                        mle->type != DLM_MLE_MASTER &&
2453                        mle->type != DLM_MLE_MIGRATION);
2454
2455                 /* MASTER mles are initiated locally.  the waiting
2456                  * process will notice the node map change
2457                  * shortly.  let that happen as normal. */
2458                 if (mle->type == DLM_MLE_MASTER)
2459                         continue;
2460
2461
2462                 /* BLOCK mles are initiated by other nodes.
2463                  * need to clean up if the dead node would have
2464                  * been the master. */
2465                 if (mle->type == DLM_MLE_BLOCK) {
2466                         int bit;
2467
2468                         spin_lock(&mle->spinlock);
2469                         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
2470                         if (bit != dead_node) {
2471                                 mlog(0, "mle found, but dead node %u would "
2472                                      "not have been master\n", dead_node);
2473                                 spin_unlock(&mle->spinlock);
2474                         } else {
2475                                 /* must drop the refcount by one since the
2476                                  * assert_master will never arrive.  this
2477                                  * may result in the mle being unlinked and
2478                                  * freed, but there may still be a process
2479                                  * waiting in the dlmlock path which is fine. */
2480                                 mlog(ML_ERROR, "node %u was expected master\n",
2481                                      dead_node);
2482                                 atomic_set(&mle->woken, 1);
2483                                 spin_unlock(&mle->spinlock);
2484                                 wake_up(&mle->wq);
2485                                 /* do not need events any longer, so detach 
2486                                  * from heartbeat */
2487                                 __dlm_mle_detach_hb_events(dlm, mle);
2488                                 __dlm_put_mle(mle);
2489                         }
2490                         continue;
2491                 }
2492
2493                 /* everything else is a MIGRATION mle */
2494
2495                 /* the rule for MIGRATION mles is that the master
2496                  * becomes UNKNOWN if *either* the original or
2497                  * the new master dies.  all UNKNOWN lockreses
2498                  * are sent to whichever node becomes the recovery
2499                  * master.  the new master is responsible for
2500                  * determining if there is still a master for
2501                  * this lockres, or if he needs to take over
2502                  * mastery.  either way, this node should expect
2503                  * another message to resolve this. */
2504                 if (mle->master != dead_node &&
2505                     mle->new_master != dead_node)
2506                         continue;
2507
2508                 /* if we have reached this point, this mle needs to
2509                  * be removed from the list and freed. */
2510
2511                 /* remove from the list early.  NOTE: unlinking
2512                  * list_head while in list_for_each_safe */
2513                 spin_lock(&mle->spinlock);
2514                 list_del_init(&mle->list);
2515                 atomic_set(&mle->woken, 1);
2516                 spin_unlock(&mle->spinlock);
2517                 wake_up(&mle->wq);
2518
2519                 mlog(0, "node %u died during migration from "
2520                      "%u to %u!\n", dead_node,
2521                      mle->master, mle->new_master);
2522                 /* if there is a lockres associated with this
2523                  * mle, find it and set its owner to UNKNOWN */
2524                 res = __dlm_lookup_lockres(dlm, mle->u.name.name,
2525                                         mle->u.name.len);
2526                 if (res) {
2527                         /* unfortunately if we hit this rare case, our
2528                          * lock ordering is messed.  we need to drop
2529                          * the master lock so that we can take the
2530                          * lockres lock, meaning that we will have to
2531                          * restart from the head of list. */
2532                         spin_unlock(&dlm->master_lock);
2533
2534                         /* move lockres onto recovery list */
2535                         spin_lock(&res->spinlock);
2536                         dlm_set_lockres_owner(dlm, res,
2537                                         DLM_LOCK_RES_OWNER_UNKNOWN);
2538                         dlm_move_lockres_to_recovery_list(dlm, res);
2539                         spin_unlock(&res->spinlock);
2540                         dlm_lockres_put(res);
2541
2542                         /* about to get rid of mle, detach from heartbeat */
2543                         __dlm_mle_detach_hb_events(dlm, mle);
2544
2545                         /* dump the mle */
2546                         spin_lock(&dlm->master_lock);
2547                         __dlm_put_mle(mle);
2548                         spin_unlock(&dlm->master_lock);
2549
2550                         /* restart */
2551                         goto top;
2552                 }
2553
2554                 /* this may be the last reference */
2555                 __dlm_put_mle(mle);
2556         }
2557         spin_unlock(&dlm->master_lock);
2558 }
2559
2560
2561 int dlm_finish_migration(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
2562                          u8 old_master)
2563 {
2564         struct dlm_node_iter iter;
2565         int ret = 0;
2566
2567         spin_lock(&dlm->spinlock);
2568         dlm_node_iter_init(dlm->domain_map, &iter);
2569         clear_bit(old_master, iter.node_map);
2570         clear_bit(dlm->node_num, iter.node_map);
2571         spin_unlock(&dlm->spinlock);
2572
2573         mlog(0, "now time to do a migrate request to other nodes\n");
2574         ret = dlm_do_migrate_request(dlm, res, old_master,
2575                                      dlm->node_num, &iter);
2576         if (ret < 0) {
2577                 mlog_errno(ret);
2578                 goto leave;
2579         }
2580
2581         mlog(0, "doing assert master of %.*s to all except the original node\n",
2582              res->lockname.len, res->lockname.name);
2583         /* this call now finishes out the nodemap
2584          * even if one or more nodes die */
2585         ret = dlm_do_assert_master(dlm, res->lockname.name,
2586                                    res->lockname.len, iter.node_map,
2587                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
2588         if (ret < 0) {
2589                 /* no longer need to retry.  all living nodes contacted. */
2590                 mlog_errno(ret);
2591                 ret = 0;
2592         }
2593
2594         memset(iter.node_map, 0, sizeof(iter.node_map));
2595         set_bit(old_master, iter.node_map);
2596         mlog(0, "doing assert master of %.*s back to %u\n",
2597              res->lockname.len, res->lockname.name, old_master);
2598         ret = dlm_do_assert_master(dlm, res->lockname.name,
2599                                    res->lockname.len, iter.node_map,
2600                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
2601         if (ret < 0) {
2602                 mlog(0, "assert master to original master failed "
2603                      "with %d.\n", ret);
2604                 /* the only nonzero status here would be because of
2605                  * a dead original node.  we're done. */
2606                 ret = 0;
2607         }
2608
2609         /* all done, set the owner, clear the flag */
2610         spin_lock(&res->spinlock);
2611         dlm_set_lockres_owner(dlm, res, dlm->node_num);
2612         res->state &= ~DLM_LOCK_RES_MIGRATING;
2613         spin_unlock(&res->spinlock);
2614         /* re-dirty it on the new master */
2615         dlm_kick_thread(dlm, res);
2616         wake_up(&res->wq);
2617 leave:
2618         return ret;
2619 }
2620
2621 /*
2622  * LOCKRES AST REFCOUNT
2623  * this is integral to migration
2624  */
2625
2626 /* for future intent to call an ast, reserve one ahead of time.
2627  * this should be called only after waiting on the lockres
2628  * with dlm_wait_on_lockres, and while still holding the
2629  * spinlock after the call. */
2630 void __dlm_lockres_reserve_ast(struct dlm_lock_resource *res)
2631 {
2632         assert_spin_locked(&res->spinlock);
2633         if (res->state & DLM_LOCK_RES_MIGRATING) {
2634                 __dlm_print_one_lock_resource(res);
2635         }
2636         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
2637
2638         atomic_inc(&res->asts_reserved);
2639 }
2640
2641 /*
2642  * used to drop the reserved ast, either because it went unused,
2643  * or because the ast/bast was actually called.
2644  *
2645  * also, if there is a pending migration on this lockres,
2646  * and this was the last pending ast on the lockres,
2647  * atomically set the MIGRATING flag before we drop the lock.
2648  * this is how we ensure that migration can proceed with no
2649  * asts in progress.  note that it is ok if the state of the
2650  * queues is such that a lock should be granted in the future
2651  * or that a bast should be fired, because the new master will
2652  * shuffle the lists on this lockres as soon as it is migrated.
2653  */
2654 void dlm_lockres_release_ast(struct dlm_ctxt *dlm,
2655                              struct dlm_lock_resource *res)
2656 {
2657         if (!atomic_dec_and_lock(&res->asts_reserved, &res->spinlock))
2658                 return;
2659
2660         if (!res->migration_pending) {
2661                 spin_unlock(&res->spinlock);
2662                 return;
2663         }
2664
2665         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
2666         res->migration_pending = 0;
2667         res->state |= DLM_LOCK_RES_MIGRATING;
2668         spin_unlock(&res->spinlock);
2669         wake_up(&res->wq);
2670         wake_up(&dlm->migration_wq);
2671 }