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Linux/fs/ocfs2/dlm/dlmmaster.c

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  1 /* -*- mode: c; c-basic-offset: 8; -*-
  2  * vim: noexpandtab sw=8 ts=8 sts=0:
  3  *
  4  * dlmmod.c
  5  *
  6  * standalone DLM module
  7  *
  8  * Copyright (C) 2004 Oracle.  All rights reserved.
  9  *
 10  * This program is free software; you can redistribute it and/or
 11  * modify it under the terms of the GNU General Public
 12  * License as published by the Free Software Foundation; either
 13  * version 2 of the License, or (at your option) any later version.
 14  *
 15  * This program is distributed in the hope that it will be useful,
 16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 18  * General Public License for more details.
 19  *
 20  * You should have received a copy of the GNU General Public
 21  * License along with this program; if not, write to the
 22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 23  * Boston, MA 021110-1307, USA.
 24  *
 25  */
 26 
 27 
 28 #include <linux/module.h>
 29 #include <linux/fs.h>
 30 #include <linux/types.h>
 31 #include <linux/slab.h>
 32 #include <linux/highmem.h>
 33 #include <linux/init.h>
 34 #include <linux/sysctl.h>
 35 #include <linux/random.h>
 36 #include <linux/blkdev.h>
 37 #include <linux/socket.h>
 38 #include <linux/inet.h>
 39 #include <linux/spinlock.h>
 40 #include <linux/delay.h>
 41 
 42 
 43 #include "cluster/heartbeat.h"
 44 #include "cluster/nodemanager.h"
 45 #include "cluster/tcp.h"
 46 
 47 #include "dlmapi.h"
 48 #include "dlmcommon.h"
 49 #include "dlmdomain.h"
 50 #include "dlmdebug.h"
 51 
 52 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
 53 #include "cluster/masklog.h"
 54 
 55 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
 56                               struct dlm_master_list_entry *mle,
 57                               struct o2nm_node *node,
 58                               int idx);
 59 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
 60                             struct dlm_master_list_entry *mle,
 61                             struct o2nm_node *node,
 62                             int idx);
 63 
 64 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data);
 65 static int dlm_do_assert_master(struct dlm_ctxt *dlm,
 66                                 struct dlm_lock_resource *res,
 67                                 void *nodemap, u32 flags);
 68 static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data);
 69 
 70 static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
 71                                 struct dlm_master_list_entry *mle,
 72                                 const char *name,
 73                                 unsigned int namelen)
 74 {
 75         if (dlm != mle->dlm)
 76                 return 0;
 77 
 78         if (namelen != mle->mnamelen ||
 79             memcmp(name, mle->mname, namelen) != 0)
 80                 return 0;
 81 
 82         return 1;
 83 }
 84 
 85 static struct kmem_cache *dlm_lockres_cache;
 86 static struct kmem_cache *dlm_lockname_cache;
 87 static struct kmem_cache *dlm_mle_cache;
 88 
 89 static void dlm_mle_release(struct kref *kref);
 90 static void dlm_init_mle(struct dlm_master_list_entry *mle,
 91                         enum dlm_mle_type type,
 92                         struct dlm_ctxt *dlm,
 93                         struct dlm_lock_resource *res,
 94                         const char *name,
 95                         unsigned int namelen);
 96 static void dlm_put_mle(struct dlm_master_list_entry *mle);
 97 static void __dlm_put_mle(struct dlm_master_list_entry *mle);
 98 static int dlm_find_mle(struct dlm_ctxt *dlm,
 99                         struct dlm_master_list_entry **mle,
100                         char *name, unsigned int namelen);
101 
102 static int dlm_do_master_request(struct dlm_lock_resource *res,
103                                  struct dlm_master_list_entry *mle, int to);
104 
105 
106 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
107                                      struct dlm_lock_resource *res,
108                                      struct dlm_master_list_entry *mle,
109                                      int *blocked);
110 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
111                                     struct dlm_lock_resource *res,
112                                     struct dlm_master_list_entry *mle,
113                                     int blocked);
114 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
115                                  struct dlm_lock_resource *res,
116                                  struct dlm_master_list_entry *mle,
117                                  struct dlm_master_list_entry **oldmle,
118                                  const char *name, unsigned int namelen,
119                                  u8 new_master, u8 master);
120 
121 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
122                                     struct dlm_lock_resource *res);
123 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
124                                       struct dlm_lock_resource *res);
125 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
126                                        struct dlm_lock_resource *res,
127                                        u8 target);
128 static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
129                                        struct dlm_lock_resource *res);
130 
131 
132 int dlm_is_host_down(int errno)
133 {
134         switch (errno) {
135                 case -EBADF:
136                 case -ECONNREFUSED:
137                 case -ENOTCONN:
138                 case -ECONNRESET:
139                 case -EPIPE:
140                 case -EHOSTDOWN:
141                 case -EHOSTUNREACH:
142                 case -ETIMEDOUT:
143                 case -ECONNABORTED:
144                 case -ENETDOWN:
145                 case -ENETUNREACH:
146                 case -ENETRESET:
147                 case -ESHUTDOWN:
148                 case -ENOPROTOOPT:
149                 case -EINVAL:   /* if returned from our tcp code,
150                                    this means there is no socket */
151                         return 1;
152         }
153         return 0;
154 }
155 
156 
157 /*
158  * MASTER LIST FUNCTIONS
159  */
160 
161 
162 /*
163  * regarding master list entries and heartbeat callbacks:
164  *
165  * in order to avoid sleeping and allocation that occurs in
166  * heartbeat, master list entries are simply attached to the
167  * dlm's established heartbeat callbacks.  the mle is attached
168  * when it is created, and since the dlm->spinlock is held at
169  * that time, any heartbeat event will be properly discovered
170  * by the mle.  the mle needs to be detached from the
171  * dlm->mle_hb_events list as soon as heartbeat events are no
172  * longer useful to the mle, and before the mle is freed.
173  *
174  * as a general rule, heartbeat events are no longer needed by
175  * the mle once an "answer" regarding the lock master has been
176  * received.
177  */
178 static inline void __dlm_mle_attach_hb_events(struct dlm_ctxt *dlm,
179                                               struct dlm_master_list_entry *mle)
180 {
181         assert_spin_locked(&dlm->spinlock);
182 
183         list_add_tail(&mle->hb_events, &dlm->mle_hb_events);
184 }
185 
186 
187 static inline void __dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
188                                               struct dlm_master_list_entry *mle)
189 {
190         if (!list_empty(&mle->hb_events))
191                 list_del_init(&mle->hb_events);
192 }
193 
194 
195 static inline void dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
196                                             struct dlm_master_list_entry *mle)
197 {
198         spin_lock(&dlm->spinlock);
199         __dlm_mle_detach_hb_events(dlm, mle);
200         spin_unlock(&dlm->spinlock);
201 }
202 
203 static void dlm_get_mle_inuse(struct dlm_master_list_entry *mle)
204 {
205         struct dlm_ctxt *dlm;
206         dlm = mle->dlm;
207 
208         assert_spin_locked(&dlm->spinlock);
209         assert_spin_locked(&dlm->master_lock);
210         mle->inuse++;
211         kref_get(&mle->mle_refs);
212 }
213 
214 static void dlm_put_mle_inuse(struct dlm_master_list_entry *mle)
215 {
216         struct dlm_ctxt *dlm;
217         dlm = mle->dlm;
218 
219         spin_lock(&dlm->spinlock);
220         spin_lock(&dlm->master_lock);
221         mle->inuse--;
222         __dlm_put_mle(mle);
223         spin_unlock(&dlm->master_lock);
224         spin_unlock(&dlm->spinlock);
225 
226 }
227 
228 /* remove from list and free */
229 static void __dlm_put_mle(struct dlm_master_list_entry *mle)
230 {
231         struct dlm_ctxt *dlm;
232         dlm = mle->dlm;
233 
234         assert_spin_locked(&dlm->spinlock);
235         assert_spin_locked(&dlm->master_lock);
236         if (!atomic_read(&mle->mle_refs.refcount)) {
237                 /* this may or may not crash, but who cares.
238                  * it's a BUG. */
239                 mlog(ML_ERROR, "bad mle: %p\n", mle);
240                 dlm_print_one_mle(mle);
241                 BUG();
242         } else
243                 kref_put(&mle->mle_refs, dlm_mle_release);
244 }
245 
246 
247 /* must not have any spinlocks coming in */
248 static void dlm_put_mle(struct dlm_master_list_entry *mle)
249 {
250         struct dlm_ctxt *dlm;
251         dlm = mle->dlm;
252 
253         spin_lock(&dlm->spinlock);
254         spin_lock(&dlm->master_lock);
255         __dlm_put_mle(mle);
256         spin_unlock(&dlm->master_lock);
257         spin_unlock(&dlm->spinlock);
258 }
259 
260 static inline void dlm_get_mle(struct dlm_master_list_entry *mle)
261 {
262         kref_get(&mle->mle_refs);
263 }
264 
265 static void dlm_init_mle(struct dlm_master_list_entry *mle,
266                         enum dlm_mle_type type,
267                         struct dlm_ctxt *dlm,
268                         struct dlm_lock_resource *res,
269                         const char *name,
270                         unsigned int namelen)
271 {
272         assert_spin_locked(&dlm->spinlock);
273 
274         mle->dlm = dlm;
275         mle->type = type;
276         INIT_HLIST_NODE(&mle->master_hash_node);
277         INIT_LIST_HEAD(&mle->hb_events);
278         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
279         spin_lock_init(&mle->spinlock);
280         init_waitqueue_head(&mle->wq);
281         atomic_set(&mle->woken, 0);
282         kref_init(&mle->mle_refs);
283         memset(mle->response_map, 0, sizeof(mle->response_map));
284         mle->master = O2NM_MAX_NODES;
285         mle->new_master = O2NM_MAX_NODES;
286         mle->inuse = 0;
287 
288         BUG_ON(mle->type != DLM_MLE_BLOCK &&
289                mle->type != DLM_MLE_MASTER &&
290                mle->type != DLM_MLE_MIGRATION);
291 
292         if (mle->type == DLM_MLE_MASTER) {
293                 BUG_ON(!res);
294                 mle->mleres = res;
295                 memcpy(mle->mname, res->lockname.name, res->lockname.len);
296                 mle->mnamelen = res->lockname.len;
297                 mle->mnamehash = res->lockname.hash;
298         } else {
299                 BUG_ON(!name);
300                 mle->mleres = NULL;
301                 memcpy(mle->mname, name, namelen);
302                 mle->mnamelen = namelen;
303                 mle->mnamehash = dlm_lockid_hash(name, namelen);
304         }
305 
306         atomic_inc(&dlm->mle_tot_count[mle->type]);
307         atomic_inc(&dlm->mle_cur_count[mle->type]);
308 
309         /* copy off the node_map and register hb callbacks on our copy */
310         memcpy(mle->node_map, dlm->domain_map, sizeof(mle->node_map));
311         memcpy(mle->vote_map, dlm->domain_map, sizeof(mle->vote_map));
312         clear_bit(dlm->node_num, mle->vote_map);
313         clear_bit(dlm->node_num, mle->node_map);
314 
315         /* attach the mle to the domain node up/down events */
316         __dlm_mle_attach_hb_events(dlm, mle);
317 }
318 
319 void __dlm_unlink_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle)
320 {
321         assert_spin_locked(&dlm->spinlock);
322         assert_spin_locked(&dlm->master_lock);
323 
324         if (!hlist_unhashed(&mle->master_hash_node))
325                 hlist_del_init(&mle->master_hash_node);
326 }
327 
328 void __dlm_insert_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle)
329 {
330         struct hlist_head *bucket;
331 
332         assert_spin_locked(&dlm->master_lock);
333 
334         bucket = dlm_master_hash(dlm, mle->mnamehash);
335         hlist_add_head(&mle->master_hash_node, bucket);
336 }
337 
338 /* returns 1 if found, 0 if not */
339 static int dlm_find_mle(struct dlm_ctxt *dlm,
340                         struct dlm_master_list_entry **mle,
341                         char *name, unsigned int namelen)
342 {
343         struct dlm_master_list_entry *tmpmle;
344         struct hlist_head *bucket;
345         unsigned int hash;
346 
347         assert_spin_locked(&dlm->master_lock);
348 
349         hash = dlm_lockid_hash(name, namelen);
350         bucket = dlm_master_hash(dlm, hash);
351         hlist_for_each_entry(tmpmle, bucket, master_hash_node) {
352                 if (!dlm_mle_equal(dlm, tmpmle, name, namelen))
353                         continue;
354                 dlm_get_mle(tmpmle);
355                 *mle = tmpmle;
356                 return 1;
357         }
358         return 0;
359 }
360 
361 void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up)
362 {
363         struct dlm_master_list_entry *mle;
364 
365         assert_spin_locked(&dlm->spinlock);
366 
367         list_for_each_entry(mle, &dlm->mle_hb_events, hb_events) {
368                 if (node_up)
369                         dlm_mle_node_up(dlm, mle, NULL, idx);
370                 else
371                         dlm_mle_node_down(dlm, mle, NULL, idx);
372         }
373 }
374 
375 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
376                               struct dlm_master_list_entry *mle,
377                               struct o2nm_node *node, int idx)
378 {
379         spin_lock(&mle->spinlock);
380 
381         if (!test_bit(idx, mle->node_map))
382                 mlog(0, "node %u already removed from nodemap!\n", idx);
383         else
384                 clear_bit(idx, mle->node_map);
385 
386         spin_unlock(&mle->spinlock);
387 }
388 
389 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
390                             struct dlm_master_list_entry *mle,
391                             struct o2nm_node *node, int idx)
392 {
393         spin_lock(&mle->spinlock);
394 
395         if (test_bit(idx, mle->node_map))
396                 mlog(0, "node %u already in node map!\n", idx);
397         else
398                 set_bit(idx, mle->node_map);
399 
400         spin_unlock(&mle->spinlock);
401 }
402 
403 
404 int dlm_init_mle_cache(void)
405 {
406         dlm_mle_cache = kmem_cache_create("o2dlm_mle",
407                                           sizeof(struct dlm_master_list_entry),
408                                           0, SLAB_HWCACHE_ALIGN,
409                                           NULL);
410         if (dlm_mle_cache == NULL)
411                 return -ENOMEM;
412         return 0;
413 }
414 
415 void dlm_destroy_mle_cache(void)
416 {
417         if (dlm_mle_cache)
418                 kmem_cache_destroy(dlm_mle_cache);
419 }
420 
421 static void dlm_mle_release(struct kref *kref)
422 {
423         struct dlm_master_list_entry *mle;
424         struct dlm_ctxt *dlm;
425 
426         mle = container_of(kref, struct dlm_master_list_entry, mle_refs);
427         dlm = mle->dlm;
428 
429         assert_spin_locked(&dlm->spinlock);
430         assert_spin_locked(&dlm->master_lock);
431 
432         mlog(0, "Releasing mle for %.*s, type %d\n", mle->mnamelen, mle->mname,
433              mle->type);
434 
435         /* remove from list if not already */
436         __dlm_unlink_mle(dlm, mle);
437 
438         /* detach the mle from the domain node up/down events */
439         __dlm_mle_detach_hb_events(dlm, mle);
440 
441         atomic_dec(&dlm->mle_cur_count[mle->type]);
442 
443         /* NOTE: kfree under spinlock here.
444          * if this is bad, we can move this to a freelist. */
445         kmem_cache_free(dlm_mle_cache, mle);
446 }
447 
448 
449 /*
450  * LOCK RESOURCE FUNCTIONS
451  */
452 
453 int dlm_init_master_caches(void)
454 {
455         dlm_lockres_cache = kmem_cache_create("o2dlm_lockres",
456                                               sizeof(struct dlm_lock_resource),
457                                               0, SLAB_HWCACHE_ALIGN, NULL);
458         if (!dlm_lockres_cache)
459                 goto bail;
460 
461         dlm_lockname_cache = kmem_cache_create("o2dlm_lockname",
462                                                DLM_LOCKID_NAME_MAX, 0,
463                                                SLAB_HWCACHE_ALIGN, NULL);
464         if (!dlm_lockname_cache)
465                 goto bail;
466 
467         return 0;
468 bail:
469         dlm_destroy_master_caches();
470         return -ENOMEM;
471 }
472 
473 void dlm_destroy_master_caches(void)
474 {
475         if (dlm_lockname_cache) {
476                 kmem_cache_destroy(dlm_lockname_cache);
477                 dlm_lockname_cache = NULL;
478         }
479 
480         if (dlm_lockres_cache) {
481                 kmem_cache_destroy(dlm_lockres_cache);
482                 dlm_lockres_cache = NULL;
483         }
484 }
485 
486 static void dlm_lockres_release(struct kref *kref)
487 {
488         struct dlm_lock_resource *res;
489         struct dlm_ctxt *dlm;
490 
491         res = container_of(kref, struct dlm_lock_resource, refs);
492         dlm = res->dlm;
493 
494         /* This should not happen -- all lockres' have a name
495          * associated with them at init time. */
496         BUG_ON(!res->lockname.name);
497 
498         mlog(0, "destroying lockres %.*s\n", res->lockname.len,
499              res->lockname.name);
500 
501         atomic_dec(&dlm->res_cur_count);
502 
503         if (!hlist_unhashed(&res->hash_node) ||
504             !list_empty(&res->granted) ||
505             !list_empty(&res->converting) ||
506             !list_empty(&res->blocked) ||
507             !list_empty(&res->dirty) ||
508             !list_empty(&res->recovering) ||
509             !list_empty(&res->purge)) {
510                 mlog(ML_ERROR,
511                      "Going to BUG for resource %.*s."
512                      "  We're on a list! [%c%c%c%c%c%c%c]\n",
513                      res->lockname.len, res->lockname.name,
514                      !hlist_unhashed(&res->hash_node) ? 'H' : ' ',
515                      !list_empty(&res->granted) ? 'G' : ' ',
516                      !list_empty(&res->converting) ? 'C' : ' ',
517                      !list_empty(&res->blocked) ? 'B' : ' ',
518                      !list_empty(&res->dirty) ? 'D' : ' ',
519                      !list_empty(&res->recovering) ? 'R' : ' ',
520                      !list_empty(&res->purge) ? 'P' : ' ');
521 
522                 dlm_print_one_lock_resource(res);
523         }
524 
525         /* By the time we're ready to blow this guy away, we shouldn't
526          * be on any lists. */
527         BUG_ON(!hlist_unhashed(&res->hash_node));
528         BUG_ON(!list_empty(&res->granted));
529         BUG_ON(!list_empty(&res->converting));
530         BUG_ON(!list_empty(&res->blocked));
531         BUG_ON(!list_empty(&res->dirty));
532         BUG_ON(!list_empty(&res->recovering));
533         BUG_ON(!list_empty(&res->purge));
534 
535         kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
536 
537         kmem_cache_free(dlm_lockres_cache, res);
538 }
539 
540 void dlm_lockres_put(struct dlm_lock_resource *res)
541 {
542         kref_put(&res->refs, dlm_lockres_release);
543 }
544 
545 static void dlm_init_lockres(struct dlm_ctxt *dlm,
546                              struct dlm_lock_resource *res,
547                              const char *name, unsigned int namelen)
548 {
549         char *qname;
550 
551         /* If we memset here, we lose our reference to the kmalloc'd
552          * res->lockname.name, so be sure to init every field
553          * correctly! */
554 
555         qname = (char *) res->lockname.name;
556         memcpy(qname, name, namelen);
557 
558         res->lockname.len = namelen;
559         res->lockname.hash = dlm_lockid_hash(name, namelen);
560 
561         init_waitqueue_head(&res->wq);
562         spin_lock_init(&res->spinlock);
563         INIT_HLIST_NODE(&res->hash_node);
564         INIT_LIST_HEAD(&res->granted);
565         INIT_LIST_HEAD(&res->converting);
566         INIT_LIST_HEAD(&res->blocked);
567         INIT_LIST_HEAD(&res->dirty);
568         INIT_LIST_HEAD(&res->recovering);
569         INIT_LIST_HEAD(&res->purge);
570         INIT_LIST_HEAD(&res->tracking);
571         atomic_set(&res->asts_reserved, 0);
572         res->migration_pending = 0;
573         res->inflight_locks = 0;
574         res->inflight_assert_workers = 0;
575 
576         res->dlm = dlm;
577 
578         kref_init(&res->refs);
579 
580         atomic_inc(&dlm->res_tot_count);
581         atomic_inc(&dlm->res_cur_count);
582 
583         /* just for consistency */
584         spin_lock(&res->spinlock);
585         dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
586         spin_unlock(&res->spinlock);
587 
588         res->state = DLM_LOCK_RES_IN_PROGRESS;
589 
590         res->last_used = 0;
591 
592         spin_lock(&dlm->spinlock);
593         list_add_tail(&res->tracking, &dlm->tracking_list);
594         spin_unlock(&dlm->spinlock);
595 
596         memset(res->lvb, 0, DLM_LVB_LEN);
597         memset(res->refmap, 0, sizeof(res->refmap));
598 }
599 
600 struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
601                                    const char *name,
602                                    unsigned int namelen)
603 {
604         struct dlm_lock_resource *res = NULL;
605 
606         res = kmem_cache_zalloc(dlm_lockres_cache, GFP_NOFS);
607         if (!res)
608                 goto error;
609 
610         res->lockname.name = kmem_cache_zalloc(dlm_lockname_cache, GFP_NOFS);
611         if (!res->lockname.name)
612                 goto error;
613 
614         dlm_init_lockres(dlm, res, name, namelen);
615         return res;
616 
617 error:
618         if (res)
619                 kmem_cache_free(dlm_lockres_cache, res);
620         return NULL;
621 }
622 
623 void dlm_lockres_set_refmap_bit(struct dlm_ctxt *dlm,
624                                 struct dlm_lock_resource *res, int bit)
625 {
626         assert_spin_locked(&res->spinlock);
627 
628         mlog(0, "res %.*s, set node %u, %ps()\n", res->lockname.len,
629              res->lockname.name, bit, __builtin_return_address(0));
630 
631         set_bit(bit, res->refmap);
632 }
633 
634 void dlm_lockres_clear_refmap_bit(struct dlm_ctxt *dlm,
635                                   struct dlm_lock_resource *res, int bit)
636 {
637         assert_spin_locked(&res->spinlock);
638 
639         mlog(0, "res %.*s, clr node %u, %ps()\n", res->lockname.len,
640              res->lockname.name, bit, __builtin_return_address(0));
641 
642         clear_bit(bit, res->refmap);
643 }
644 
645 static void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
646                                    struct dlm_lock_resource *res)
647 {
648         res->inflight_locks++;
649 
650         mlog(0, "%s: res %.*s, inflight++: now %u, %ps()\n", dlm->name,
651              res->lockname.len, res->lockname.name, res->inflight_locks,
652              __builtin_return_address(0));
653 }
654 
655 void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
656                                    struct dlm_lock_resource *res)
657 {
658         assert_spin_locked(&res->spinlock);
659         __dlm_lockres_grab_inflight_ref(dlm, res);
660 }
661 
662 void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
663                                    struct dlm_lock_resource *res)
664 {
665         assert_spin_locked(&res->spinlock);
666 
667         BUG_ON(res->inflight_locks == 0);
668 
669         res->inflight_locks--;
670 
671         mlog(0, "%s: res %.*s, inflight--: now %u, %ps()\n", dlm->name,
672              res->lockname.len, res->lockname.name, res->inflight_locks,
673              __builtin_return_address(0));
674 
675         wake_up(&res->wq);
676 }
677 
678 void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
679                 struct dlm_lock_resource *res)
680 {
681         assert_spin_locked(&res->spinlock);
682         res->inflight_assert_workers++;
683         mlog(0, "%s:%.*s: inflight assert worker++: now %u\n",
684                         dlm->name, res->lockname.len, res->lockname.name,
685                         res->inflight_assert_workers);
686 }
687 
688 static void __dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
689                 struct dlm_lock_resource *res)
690 {
691         assert_spin_locked(&res->spinlock);
692         BUG_ON(res->inflight_assert_workers == 0);
693         res->inflight_assert_workers--;
694         mlog(0, "%s:%.*s: inflight assert worker--: now %u\n",
695                         dlm->name, res->lockname.len, res->lockname.name,
696                         res->inflight_assert_workers);
697 }
698 
699 static void dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
700                 struct dlm_lock_resource *res)
701 {
702         spin_lock(&res->spinlock);
703         __dlm_lockres_drop_inflight_worker(dlm, res);
704         spin_unlock(&res->spinlock);
705 }
706 
707 /*
708  * lookup a lock resource by name.
709  * may already exist in the hashtable.
710  * lockid is null terminated
711  *
712  * if not, allocate enough for the lockres and for
713  * the temporary structure used in doing the mastering.
714  *
715  * also, do a lookup in the dlm->master_list to see
716  * if another node has begun mastering the same lock.
717  * if so, there should be a block entry in there
718  * for this name, and we should *not* attempt to master
719  * the lock here.   need to wait around for that node
720  * to assert_master (or die).
721  *
722  */
723 struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm,
724                                           const char *lockid,
725                                           int namelen,
726                                           int flags)
727 {
728         struct dlm_lock_resource *tmpres=NULL, *res=NULL;
729         struct dlm_master_list_entry *mle = NULL;
730         struct dlm_master_list_entry *alloc_mle = NULL;
731         int blocked = 0;
732         int ret, nodenum;
733         struct dlm_node_iter iter;
734         unsigned int hash;
735         int tries = 0;
736         int bit, wait_on_recovery = 0;
737 
738         BUG_ON(!lockid);
739 
740         hash = dlm_lockid_hash(lockid, namelen);
741 
742         mlog(0, "get lockres %s (len %d)\n", lockid, namelen);
743 
744 lookup:
745         spin_lock(&dlm->spinlock);
746         tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash);
747         if (tmpres) {
748                 spin_unlock(&dlm->spinlock);
749                 spin_lock(&tmpres->spinlock);
750 
751                 /*
752                  * Right after dlm spinlock was released, dlm_thread could have
753                  * purged the lockres. Check if lockres got unhashed. If so
754                  * start over.
755                  */
756                 if (hlist_unhashed(&tmpres->hash_node)) {
757                         spin_unlock(&tmpres->spinlock);
758                         dlm_lockres_put(tmpres);
759                         tmpres = NULL;
760                         goto lookup;
761                 }
762 
763                 /* Wait on the thread that is mastering the resource */
764                 if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
765                         __dlm_wait_on_lockres(tmpres);
766                         BUG_ON(tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN);
767                         spin_unlock(&tmpres->spinlock);
768                         dlm_lockres_put(tmpres);
769                         tmpres = NULL;
770                         goto lookup;
771                 }
772 
773                 /* Wait on the resource purge to complete before continuing */
774                 if (tmpres->state & DLM_LOCK_RES_DROPPING_REF) {
775                         BUG_ON(tmpres->owner == dlm->node_num);
776                         __dlm_wait_on_lockres_flags(tmpres,
777                                                     DLM_LOCK_RES_DROPPING_REF);
778                         spin_unlock(&tmpres->spinlock);
779                         dlm_lockres_put(tmpres);
780                         tmpres = NULL;
781                         goto lookup;
782                 }
783 
784                 /* Grab inflight ref to pin the resource */
785                 dlm_lockres_grab_inflight_ref(dlm, tmpres);
786 
787                 spin_unlock(&tmpres->spinlock);
788                 if (res) {
789                         spin_lock(&dlm->track_lock);
790                         if (!list_empty(&res->tracking))
791                                 list_del_init(&res->tracking);
792                         else
793                                 mlog(ML_ERROR, "Resource %.*s not "
794                                                 "on the Tracking list\n",
795                                                 res->lockname.len,
796                                                 res->lockname.name);
797                         spin_unlock(&dlm->track_lock);
798                         dlm_lockres_put(res);
799                 }
800                 res = tmpres;
801                 goto leave;
802         }
803 
804         if (!res) {
805                 spin_unlock(&dlm->spinlock);
806                 mlog(0, "allocating a new resource\n");
807                 /* nothing found and we need to allocate one. */
808                 alloc_mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
809                 if (!alloc_mle)
810                         goto leave;
811                 res = dlm_new_lockres(dlm, lockid, namelen);
812                 if (!res)
813                         goto leave;
814                 goto lookup;
815         }
816 
817         mlog(0, "no lockres found, allocated our own: %p\n", res);
818 
819         if (flags & LKM_LOCAL) {
820                 /* caller knows it's safe to assume it's not mastered elsewhere
821                  * DONE!  return right away */
822                 spin_lock(&res->spinlock);
823                 dlm_change_lockres_owner(dlm, res, dlm->node_num);
824                 __dlm_insert_lockres(dlm, res);
825                 dlm_lockres_grab_inflight_ref(dlm, res);
826                 spin_unlock(&res->spinlock);
827                 spin_unlock(&dlm->spinlock);
828                 /* lockres still marked IN_PROGRESS */
829                 goto wake_waiters;
830         }
831 
832         /* check master list to see if another node has started mastering it */
833         spin_lock(&dlm->master_lock);
834 
835         /* if we found a block, wait for lock to be mastered by another node */
836         blocked = dlm_find_mle(dlm, &mle, (char *)lockid, namelen);
837         if (blocked) {
838                 int mig;
839                 if (mle->type == DLM_MLE_MASTER) {
840                         mlog(ML_ERROR, "master entry for nonexistent lock!\n");
841                         BUG();
842                 }
843                 mig = (mle->type == DLM_MLE_MIGRATION);
844                 /* if there is a migration in progress, let the migration
845                  * finish before continuing.  we can wait for the absence
846                  * of the MIGRATION mle: either the migrate finished or
847                  * one of the nodes died and the mle was cleaned up.
848                  * if there is a BLOCK here, but it already has a master
849                  * set, we are too late.  the master does not have a ref
850                  * for us in the refmap.  detach the mle and drop it.
851                  * either way, go back to the top and start over. */
852                 if (mig || mle->master != O2NM_MAX_NODES) {
853                         BUG_ON(mig && mle->master == dlm->node_num);
854                         /* we arrived too late.  the master does not
855                          * have a ref for us. retry. */
856                         mlog(0, "%s:%.*s: late on %s\n",
857                              dlm->name, namelen, lockid,
858                              mig ?  "MIGRATION" : "BLOCK");
859                         spin_unlock(&dlm->master_lock);
860                         spin_unlock(&dlm->spinlock);
861 
862                         /* master is known, detach */
863                         if (!mig)
864                                 dlm_mle_detach_hb_events(dlm, mle);
865                         dlm_put_mle(mle);
866                         mle = NULL;
867                         /* this is lame, but we can't wait on either
868                          * the mle or lockres waitqueue here */
869                         if (mig)
870                                 msleep(100);
871                         goto lookup;
872                 }
873         } else {
874                 /* go ahead and try to master lock on this node */
875                 mle = alloc_mle;
876                 /* make sure this does not get freed below */
877                 alloc_mle = NULL;
878                 dlm_init_mle(mle, DLM_MLE_MASTER, dlm, res, NULL, 0);
879                 set_bit(dlm->node_num, mle->maybe_map);
880                 __dlm_insert_mle(dlm, mle);
881 
882                 /* still holding the dlm spinlock, check the recovery map
883                  * to see if there are any nodes that still need to be
884                  * considered.  these will not appear in the mle nodemap
885                  * but they might own this lockres.  wait on them. */
886                 bit = find_next_bit(dlm->recovery_map, O2NM_MAX_NODES, 0);
887                 if (bit < O2NM_MAX_NODES) {
888                         mlog(0, "%s: res %.*s, At least one node (%d) "
889                              "to recover before lock mastery can begin\n",
890                              dlm->name, namelen, (char *)lockid, bit);
891                         wait_on_recovery = 1;
892                 }
893         }
894 
895         /* at this point there is either a DLM_MLE_BLOCK or a
896          * DLM_MLE_MASTER on the master list, so it's safe to add the
897          * lockres to the hashtable.  anyone who finds the lock will
898          * still have to wait on the IN_PROGRESS. */
899 
900         /* finally add the lockres to its hash bucket */
901         __dlm_insert_lockres(dlm, res);
902 
903         /* since this lockres is new it doesn't not require the spinlock */
904         __dlm_lockres_grab_inflight_ref(dlm, res);
905 
906         /* get an extra ref on the mle in case this is a BLOCK
907          * if so, the creator of the BLOCK may try to put the last
908          * ref at this time in the assert master handler, so we
909          * need an extra one to keep from a bad ptr deref. */
910         dlm_get_mle_inuse(mle);
911         spin_unlock(&dlm->master_lock);
912         spin_unlock(&dlm->spinlock);
913 
914 redo_request:
915         while (wait_on_recovery) {
916                 /* any cluster changes that occurred after dropping the
917                  * dlm spinlock would be detectable be a change on the mle,
918                  * so we only need to clear out the recovery map once. */
919                 if (dlm_is_recovery_lock(lockid, namelen)) {
920                         mlog(0, "%s: Recovery map is not empty, but must "
921                              "master $RECOVERY lock now\n", dlm->name);
922                         if (!dlm_pre_master_reco_lockres(dlm, res))
923                                 wait_on_recovery = 0;
924                         else {
925                                 mlog(0, "%s: waiting 500ms for heartbeat state "
926                                     "change\n", dlm->name);
927                                 msleep(500);
928                         }
929                         continue;
930                 }
931 
932                 dlm_kick_recovery_thread(dlm);
933                 msleep(1000);
934                 dlm_wait_for_recovery(dlm);
935 
936                 spin_lock(&dlm->spinlock);
937                 bit = find_next_bit(dlm->recovery_map, O2NM_MAX_NODES, 0);
938                 if (bit < O2NM_MAX_NODES) {
939                         mlog(0, "%s: res %.*s, At least one node (%d) "
940                              "to recover before lock mastery can begin\n",
941                              dlm->name, namelen, (char *)lockid, bit);
942                         wait_on_recovery = 1;
943                 } else
944                         wait_on_recovery = 0;
945                 spin_unlock(&dlm->spinlock);
946 
947                 if (wait_on_recovery)
948                         dlm_wait_for_node_recovery(dlm, bit, 10000);
949         }
950 
951         /* must wait for lock to be mastered elsewhere */
952         if (blocked)
953                 goto wait;
954 
955         ret = -EINVAL;
956         dlm_node_iter_init(mle->vote_map, &iter);
957         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
958                 ret = dlm_do_master_request(res, mle, nodenum);
959                 if (ret < 0)
960                         mlog_errno(ret);
961                 if (mle->master != O2NM_MAX_NODES) {
962                         /* found a master ! */
963                         if (mle->master <= nodenum)
964                                 break;
965                         /* if our master request has not reached the master
966                          * yet, keep going until it does.  this is how the
967                          * master will know that asserts are needed back to
968                          * the lower nodes. */
969                         mlog(0, "%s: res %.*s, Requests only up to %u but "
970                              "master is %u, keep going\n", dlm->name, namelen,
971                              lockid, nodenum, mle->master);
972                 }
973         }
974 
975 wait:
976         /* keep going until the response map includes all nodes */
977         ret = dlm_wait_for_lock_mastery(dlm, res, mle, &blocked);
978         if (ret < 0) {
979                 wait_on_recovery = 1;
980                 mlog(0, "%s: res %.*s, Node map changed, redo the master "
981                      "request now, blocked=%d\n", dlm->name, res->lockname.len,
982                      res->lockname.name, blocked);
983                 if (++tries > 20) {
984                         mlog(ML_ERROR, "%s: res %.*s, Spinning on "
985                              "dlm_wait_for_lock_mastery, blocked = %d\n",
986                              dlm->name, res->lockname.len,
987                              res->lockname.name, blocked);
988                         dlm_print_one_lock_resource(res);
989                         dlm_print_one_mle(mle);
990                         tries = 0;
991                 }
992                 goto redo_request;
993         }
994 
995         mlog(0, "%s: res %.*s, Mastered by %u\n", dlm->name, res->lockname.len,
996              res->lockname.name, res->owner);
997         /* make sure we never continue without this */
998         BUG_ON(res->owner == O2NM_MAX_NODES);
999 
1000         /* master is known, detach if not already detached */
1001         dlm_mle_detach_hb_events(dlm, mle);
1002         dlm_put_mle(mle);
1003         /* put the extra ref */
1004         dlm_put_mle_inuse(mle);
1005 
1006 wake_waiters:
1007         spin_lock(&res->spinlock);
1008         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
1009         spin_unlock(&res->spinlock);
1010         wake_up(&res->wq);
1011 
1012 leave:
1013         /* need to free the unused mle */
1014         if (alloc_mle)
1015                 kmem_cache_free(dlm_mle_cache, alloc_mle);
1016 
1017         return res;
1018 }
1019 
1020 
1021 #define DLM_MASTERY_TIMEOUT_MS   5000
1022 
1023 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
1024                                      struct dlm_lock_resource *res,
1025                                      struct dlm_master_list_entry *mle,
1026                                      int *blocked)
1027 {
1028         u8 m;
1029         int ret, bit;
1030         int map_changed, voting_done;
1031         int assert, sleep;
1032 
1033 recheck:
1034         ret = 0;
1035         assert = 0;
1036 
1037         /* check if another node has already become the owner */
1038         spin_lock(&res->spinlock);
1039         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1040                 mlog(0, "%s:%.*s: owner is suddenly %u\n", dlm->name,
1041                      res->lockname.len, res->lockname.name, res->owner);
1042                 spin_unlock(&res->spinlock);
1043                 /* this will cause the master to re-assert across
1044                  * the whole cluster, freeing up mles */
1045                 if (res->owner != dlm->node_num) {
1046                         ret = dlm_do_master_request(res, mle, res->owner);
1047                         if (ret < 0) {
1048                                 /* give recovery a chance to run */
1049                                 mlog(ML_ERROR, "link to %u went down?: %d\n", res->owner, ret);
1050                                 msleep(500);
1051                                 goto recheck;
1052                         }
1053                 }
1054                 ret = 0;
1055                 goto leave;
1056         }
1057         spin_unlock(&res->spinlock);
1058 
1059         spin_lock(&mle->spinlock);
1060         m = mle->master;
1061         map_changed = (memcmp(mle->vote_map, mle->node_map,
1062                               sizeof(mle->vote_map)) != 0);
1063         voting_done = (memcmp(mle->vote_map, mle->response_map,
1064                              sizeof(mle->vote_map)) == 0);
1065 
1066         /* restart if we hit any errors */
1067         if (map_changed) {
1068                 int b;
1069                 mlog(0, "%s: %.*s: node map changed, restarting\n",
1070                      dlm->name, res->lockname.len, res->lockname.name);
1071                 ret = dlm_restart_lock_mastery(dlm, res, mle, *blocked);
1072                 b = (mle->type == DLM_MLE_BLOCK);
1073                 if ((*blocked && !b) || (!*blocked && b)) {
1074                         mlog(0, "%s:%.*s: status change: old=%d new=%d\n",
1075                              dlm->name, res->lockname.len, res->lockname.name,
1076                              *blocked, b);
1077                         *blocked = b;
1078                 }
1079                 spin_unlock(&mle->spinlock);
1080                 if (ret < 0) {
1081                         mlog_errno(ret);
1082                         goto leave;
1083                 }
1084                 mlog(0, "%s:%.*s: restart lock mastery succeeded, "
1085                      "rechecking now\n", dlm->name, res->lockname.len,
1086                      res->lockname.name);
1087                 goto recheck;
1088         } else {
1089                 if (!voting_done) {
1090                         mlog(0, "map not changed and voting not done "
1091                              "for %s:%.*s\n", dlm->name, res->lockname.len,
1092                              res->lockname.name);
1093                 }
1094         }
1095 
1096         if (m != O2NM_MAX_NODES) {
1097                 /* another node has done an assert!
1098                  * all done! */
1099                 sleep = 0;
1100         } else {
1101                 sleep = 1;
1102                 /* have all nodes responded? */
1103                 if (voting_done && !*blocked) {
1104                         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
1105                         if (dlm->node_num <= bit) {
1106                                 /* my node number is lowest.
1107                                  * now tell other nodes that I am
1108                                  * mastering this. */
1109                                 mle->master = dlm->node_num;
1110                                 /* ref was grabbed in get_lock_resource
1111                                  * will be dropped in dlmlock_master */
1112                                 assert = 1;
1113                                 sleep = 0;
1114                         }
1115                         /* if voting is done, but we have not received
1116                          * an assert master yet, we must sleep */
1117                 }
1118         }
1119 
1120         spin_unlock(&mle->spinlock);
1121 
1122         /* sleep if we haven't finished voting yet */
1123         if (sleep) {
1124                 unsigned long timeo = msecs_to_jiffies(DLM_MASTERY_TIMEOUT_MS);
1125 
1126                 /*
1127                 if (atomic_read(&mle->mle_refs.refcount) < 2)
1128                         mlog(ML_ERROR, "mle (%p) refs=%d, name=%.*s\n", mle,
1129                         atomic_read(&mle->mle_refs.refcount),
1130                         res->lockname.len, res->lockname.name);
1131                 */
1132                 atomic_set(&mle->woken, 0);
1133                 (void)wait_event_timeout(mle->wq,
1134                                          (atomic_read(&mle->woken) == 1),
1135                                          timeo);
1136                 if (res->owner == O2NM_MAX_NODES) {
1137                         mlog(0, "%s:%.*s: waiting again\n", dlm->name,
1138                              res->lockname.len, res->lockname.name);
1139                         goto recheck;
1140                 }
1141                 mlog(0, "done waiting, master is %u\n", res->owner);
1142                 ret = 0;
1143                 goto leave;
1144         }
1145 
1146         ret = 0;   /* done */
1147         if (assert) {
1148                 m = dlm->node_num;
1149                 mlog(0, "about to master %.*s here, this=%u\n",
1150                      res->lockname.len, res->lockname.name, m);
1151                 ret = dlm_do_assert_master(dlm, res, mle->vote_map, 0);
1152                 if (ret) {
1153                         /* This is a failure in the network path,
1154                          * not in the response to the assert_master
1155                          * (any nonzero response is a BUG on this node).
1156                          * Most likely a socket just got disconnected
1157                          * due to node death. */
1158                         mlog_errno(ret);
1159                 }
1160                 /* no longer need to restart lock mastery.
1161                  * all living nodes have been contacted. */
1162                 ret = 0;
1163         }
1164 
1165         /* set the lockres owner */
1166         spin_lock(&res->spinlock);
1167         /* mastery reference obtained either during
1168          * assert_master_handler or in get_lock_resource */
1169         dlm_change_lockres_owner(dlm, res, m);
1170         spin_unlock(&res->spinlock);
1171 
1172 leave:
1173         return ret;
1174 }
1175 
1176 struct dlm_bitmap_diff_iter
1177 {
1178         int curnode;
1179         unsigned long *orig_bm;
1180         unsigned long *cur_bm;
1181         unsigned long diff_bm[BITS_TO_LONGS(O2NM_MAX_NODES)];
1182 };
1183 
1184 enum dlm_node_state_change
1185 {
1186         NODE_DOWN = -1,
1187         NODE_NO_CHANGE = 0,
1188         NODE_UP
1189 };
1190 
1191 static void dlm_bitmap_diff_iter_init(struct dlm_bitmap_diff_iter *iter,
1192                                       unsigned long *orig_bm,
1193                                       unsigned long *cur_bm)
1194 {
1195         unsigned long p1, p2;
1196         int i;
1197 
1198         iter->curnode = -1;
1199         iter->orig_bm = orig_bm;
1200         iter->cur_bm = cur_bm;
1201 
1202         for (i = 0; i < BITS_TO_LONGS(O2NM_MAX_NODES); i++) {
1203                 p1 = *(iter->orig_bm + i);
1204                 p2 = *(iter->cur_bm + i);
1205                 iter->diff_bm[i] = (p1 & ~p2) | (p2 & ~p1);
1206         }
1207 }
1208 
1209 static int dlm_bitmap_diff_iter_next(struct dlm_bitmap_diff_iter *iter,
1210                                      enum dlm_node_state_change *state)
1211 {
1212         int bit;
1213 
1214         if (iter->curnode >= O2NM_MAX_NODES)
1215                 return -ENOENT;
1216 
1217         bit = find_next_bit(iter->diff_bm, O2NM_MAX_NODES,
1218                             iter->curnode+1);
1219         if (bit >= O2NM_MAX_NODES) {
1220                 iter->curnode = O2NM_MAX_NODES;
1221                 return -ENOENT;
1222         }
1223 
1224         /* if it was there in the original then this node died */
1225         if (test_bit(bit, iter->orig_bm))
1226                 *state = NODE_DOWN;
1227         else
1228                 *state = NODE_UP;
1229 
1230         iter->curnode = bit;
1231         return bit;
1232 }
1233 
1234 
1235 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
1236                                     struct dlm_lock_resource *res,
1237                                     struct dlm_master_list_entry *mle,
1238                                     int blocked)
1239 {
1240         struct dlm_bitmap_diff_iter bdi;
1241         enum dlm_node_state_change sc;
1242         int node;
1243         int ret = 0;
1244 
1245         mlog(0, "something happened such that the "
1246              "master process may need to be restarted!\n");
1247 
1248         assert_spin_locked(&mle->spinlock);
1249 
1250         dlm_bitmap_diff_iter_init(&bdi, mle->vote_map, mle->node_map);
1251         node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1252         while (node >= 0) {
1253                 if (sc == NODE_UP) {
1254                         /* a node came up.  clear any old vote from
1255                          * the response map and set it in the vote map
1256                          * then restart the mastery. */
1257                         mlog(ML_NOTICE, "node %d up while restarting\n", node);
1258 
1259                         /* redo the master request, but only for the new node */
1260                         mlog(0, "sending request to new node\n");
1261                         clear_bit(node, mle->response_map);
1262                         set_bit(node, mle->vote_map);
1263                 } else {
1264                         mlog(ML_ERROR, "node down! %d\n", node);
1265                         if (blocked) {
1266                                 int lowest = find_next_bit(mle->maybe_map,
1267                                                        O2NM_MAX_NODES, 0);
1268 
1269                                 /* act like it was never there */
1270                                 clear_bit(node, mle->maybe_map);
1271 
1272                                 if (node == lowest) {
1273                                         mlog(0, "expected master %u died"
1274                                             " while this node was blocked "
1275                                             "waiting on it!\n", node);
1276                                         lowest = find_next_bit(mle->maybe_map,
1277                                                         O2NM_MAX_NODES,
1278                                                         lowest+1);
1279                                         if (lowest < O2NM_MAX_NODES) {
1280                                                 mlog(0, "%s:%.*s:still "
1281                                                      "blocked. waiting on %u "
1282                                                      "now\n", dlm->name,
1283                                                      res->lockname.len,
1284                                                      res->lockname.name,
1285                                                      lowest);
1286                                         } else {
1287                                                 /* mle is an MLE_BLOCK, but
1288                                                  * there is now nothing left to
1289                                                  * block on.  we need to return
1290                                                  * all the way back out and try
1291                                                  * again with an MLE_MASTER.
1292                                                  * dlm_do_local_recovery_cleanup
1293                                                  * has already run, so the mle
1294                                                  * refcount is ok */
1295                                                 mlog(0, "%s:%.*s: no "
1296                                                      "longer blocking. try to "
1297                                                      "master this here\n",
1298                                                      dlm->name,
1299                                                      res->lockname.len,
1300                                                      res->lockname.name);
1301                                                 mle->type = DLM_MLE_MASTER;
1302                                                 mle->mleres = res;
1303                                         }
1304                                 }
1305                         }
1306 
1307                         /* now blank out everything, as if we had never
1308                          * contacted anyone */
1309                         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
1310                         memset(mle->response_map, 0, sizeof(mle->response_map));
1311                         /* reset the vote_map to the current node_map */
1312                         memcpy(mle->vote_map, mle->node_map,
1313                                sizeof(mle->node_map));
1314                         /* put myself into the maybe map */
1315                         if (mle->type != DLM_MLE_BLOCK)
1316                                 set_bit(dlm->node_num, mle->maybe_map);
1317                 }
1318                 ret = -EAGAIN;
1319                 node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1320         }
1321         return ret;
1322 }
1323 
1324 
1325 /*
1326  * DLM_MASTER_REQUEST_MSG
1327  *
1328  * returns: 0 on success,
1329  *          -errno on a network error
1330  *
1331  * on error, the caller should assume the target node is "dead"
1332  *
1333  */
1334 
1335 static int dlm_do_master_request(struct dlm_lock_resource *res,
1336                                  struct dlm_master_list_entry *mle, int to)
1337 {
1338         struct dlm_ctxt *dlm = mle->dlm;
1339         struct dlm_master_request request;
1340         int ret, response=0, resend;
1341 
1342         memset(&request, 0, sizeof(request));
1343         request.node_idx = dlm->node_num;
1344 
1345         BUG_ON(mle->type == DLM_MLE_MIGRATION);
1346 
1347         request.namelen = (u8)mle->mnamelen;
1348         memcpy(request.name, mle->mname, request.namelen);
1349 
1350 again:
1351         ret = o2net_send_message(DLM_MASTER_REQUEST_MSG, dlm->key, &request,
1352                                  sizeof(request), to, &response);
1353         if (ret < 0)  {
1354                 if (ret == -ESRCH) {
1355                         /* should never happen */
1356                         mlog(ML_ERROR, "TCP stack not ready!\n");
1357                         BUG();
1358                 } else if (ret == -EINVAL) {
1359                         mlog(ML_ERROR, "bad args passed to o2net!\n");
1360                         BUG();
1361                 } else if (ret == -ENOMEM) {
1362                         mlog(ML_ERROR, "out of memory while trying to send "
1363                              "network message!  retrying\n");
1364                         /* this is totally crude */
1365                         msleep(50);
1366                         goto again;
1367                 } else if (!dlm_is_host_down(ret)) {
1368                         /* not a network error. bad. */
1369                         mlog_errno(ret);
1370                         mlog(ML_ERROR, "unhandled error!");
1371                         BUG();
1372                 }
1373                 /* all other errors should be network errors,
1374                  * and likely indicate node death */
1375                 mlog(ML_ERROR, "link to %d went down!\n", to);
1376                 goto out;
1377         }
1378 
1379         ret = 0;
1380         resend = 0;
1381         spin_lock(&mle->spinlock);
1382         switch (response) {
1383                 case DLM_MASTER_RESP_YES:
1384                         set_bit(to, mle->response_map);
1385                         mlog(0, "node %u is the master, response=YES\n", to);
1386                         mlog(0, "%s:%.*s: master node %u now knows I have a "
1387                              "reference\n", dlm->name, res->lockname.len,
1388                              res->lockname.name, to);
1389                         mle->master = to;
1390                         break;
1391                 case DLM_MASTER_RESP_NO:
1392                         mlog(0, "node %u not master, response=NO\n", to);
1393                         set_bit(to, mle->response_map);
1394                         break;
1395                 case DLM_MASTER_RESP_MAYBE:
1396                         mlog(0, "node %u not master, response=MAYBE\n", to);
1397                         set_bit(to, mle->response_map);
1398                         set_bit(to, mle->maybe_map);
1399                         break;
1400                 case DLM_MASTER_RESP_ERROR:
1401                         mlog(0, "node %u hit an error, resending\n", to);
1402                         resend = 1;
1403                         response = 0;
1404                         break;
1405                 default:
1406                         mlog(ML_ERROR, "bad response! %u\n", response);
1407                         BUG();
1408         }
1409         spin_unlock(&mle->spinlock);
1410         if (resend) {
1411                 /* this is also totally crude */
1412                 msleep(50);
1413                 goto again;
1414         }
1415 
1416 out:
1417         return ret;
1418 }
1419 
1420 /*
1421  * locks that can be taken here:
1422  * dlm->spinlock
1423  * res->spinlock
1424  * mle->spinlock
1425  * dlm->master_list
1426  *
1427  * if possible, TRIM THIS DOWN!!!
1428  */
1429 int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data,
1430                                void **ret_data)
1431 {
1432         u8 response = DLM_MASTER_RESP_MAYBE;
1433         struct dlm_ctxt *dlm = data;
1434         struct dlm_lock_resource *res = NULL;
1435         struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
1436         struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
1437         char *name;
1438         unsigned int namelen, hash;
1439         int found, ret;
1440         int set_maybe;
1441         int dispatch_assert = 0;
1442         int dispatched = 0;
1443 
1444         if (!dlm_grab(dlm))
1445                 return DLM_MASTER_RESP_NO;
1446 
1447         if (!dlm_domain_fully_joined(dlm)) {
1448                 response = DLM_MASTER_RESP_NO;
1449                 goto send_response;
1450         }
1451 
1452         name = request->name;
1453         namelen = request->namelen;
1454         hash = dlm_lockid_hash(name, namelen);
1455 
1456         if (namelen > DLM_LOCKID_NAME_MAX) {
1457                 response = DLM_IVBUFLEN;
1458                 goto send_response;
1459         }
1460 
1461 way_up_top:
1462         spin_lock(&dlm->spinlock);
1463         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
1464         if (res) {
1465                 spin_unlock(&dlm->spinlock);
1466 
1467                 /* take care of the easy cases up front */
1468                 spin_lock(&res->spinlock);
1469 
1470                 /*
1471                  * Right after dlm spinlock was released, dlm_thread could have
1472                  * purged the lockres. Check if lockres got unhashed. If so
1473                  * start over.
1474                  */
1475                 if (hlist_unhashed(&res->hash_node)) {
1476                         spin_unlock(&res->spinlock);
1477                         dlm_lockres_put(res);
1478                         goto way_up_top;
1479                 }
1480 
1481                 if (res->state & (DLM_LOCK_RES_RECOVERING|
1482                                   DLM_LOCK_RES_MIGRATING)) {
1483                         spin_unlock(&res->spinlock);
1484                         mlog(0, "returning DLM_MASTER_RESP_ERROR since res is "
1485                              "being recovered/migrated\n");
1486                         response = DLM_MASTER_RESP_ERROR;
1487                         if (mle)
1488                                 kmem_cache_free(dlm_mle_cache, mle);
1489                         goto send_response;
1490                 }
1491 
1492                 if (res->owner == dlm->node_num) {
1493                         dlm_lockres_set_refmap_bit(dlm, res, request->node_idx);
1494                         spin_unlock(&res->spinlock);
1495                         response = DLM_MASTER_RESP_YES;
1496                         if (mle)
1497                                 kmem_cache_free(dlm_mle_cache, mle);
1498 
1499                         /* this node is the owner.
1500                          * there is some extra work that needs to
1501                          * happen now.  the requesting node has
1502                          * caused all nodes up to this one to
1503                          * create mles.  this node now needs to
1504                          * go back and clean those up. */
1505                         dispatch_assert = 1;
1506                         goto send_response;
1507                 } else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1508                         spin_unlock(&res->spinlock);
1509                         // mlog(0, "node %u is the master\n", res->owner);
1510                         response = DLM_MASTER_RESP_NO;
1511                         if (mle)
1512                                 kmem_cache_free(dlm_mle_cache, mle);
1513                         goto send_response;
1514                 }
1515 
1516                 /* ok, there is no owner.  either this node is
1517                  * being blocked, or it is actively trying to
1518                  * master this lock. */
1519                 if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1520                         mlog(ML_ERROR, "lock with no owner should be "
1521                              "in-progress!\n");
1522                         BUG();
1523                 }
1524 
1525                 // mlog(0, "lockres is in progress...\n");
1526                 spin_lock(&dlm->master_lock);
1527                 found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1528                 if (!found) {
1529                         mlog(ML_ERROR, "no mle found for this lock!\n");
1530                         BUG();
1531                 }
1532                 set_maybe = 1;
1533                 spin_lock(&tmpmle->spinlock);
1534                 if (tmpmle->type == DLM_MLE_BLOCK) {
1535                         // mlog(0, "this node is waiting for "
1536                         // "lockres to be mastered\n");
1537                         response = DLM_MASTER_RESP_NO;
1538                 } else if (tmpmle->type == DLM_MLE_MIGRATION) {
1539                         mlog(0, "node %u is master, but trying to migrate to "
1540                              "node %u.\n", tmpmle->master, tmpmle->new_master);
1541                         if (tmpmle->master == dlm->node_num) {
1542                                 mlog(ML_ERROR, "no owner on lockres, but this "
1543                                      "node is trying to migrate it to %u?!\n",
1544                                      tmpmle->new_master);
1545                                 BUG();
1546                         } else {
1547                                 /* the real master can respond on its own */
1548                                 response = DLM_MASTER_RESP_NO;
1549                         }
1550                 } else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
1551                         set_maybe = 0;
1552                         if (tmpmle->master == dlm->node_num) {
1553                                 response = DLM_MASTER_RESP_YES;
1554                                 /* this node will be the owner.
1555                                  * go back and clean the mles on any
1556                                  * other nodes */
1557                                 dispatch_assert = 1;
1558                                 dlm_lockres_set_refmap_bit(dlm, res,
1559                                                            request->node_idx);
1560                         } else
1561                                 response = DLM_MASTER_RESP_NO;
1562                 } else {
1563                         // mlog(0, "this node is attempting to "
1564                         // "master lockres\n");
1565                         response = DLM_MASTER_RESP_MAYBE;
1566                 }
1567                 if (set_maybe)
1568                         set_bit(request->node_idx, tmpmle->maybe_map);
1569                 spin_unlock(&tmpmle->spinlock);
1570 
1571                 spin_unlock(&dlm->master_lock);
1572                 spin_unlock(&res->spinlock);
1573 
1574                 /* keep the mle attached to heartbeat events */
1575                 dlm_put_mle(tmpmle);
1576                 if (mle)
1577                         kmem_cache_free(dlm_mle_cache, mle);
1578                 goto send_response;
1579         }
1580 
1581         /*
1582          * lockres doesn't exist on this node
1583          * if there is an MLE_BLOCK, return NO
1584          * if there is an MLE_MASTER, return MAYBE
1585          * otherwise, add an MLE_BLOCK, return NO
1586          */
1587         spin_lock(&dlm->master_lock);
1588         found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1589         if (!found) {
1590                 /* this lockid has never been seen on this node yet */
1591                 // mlog(0, "no mle found\n");
1592                 if (!mle) {
1593                         spin_unlock(&dlm->master_lock);
1594                         spin_unlock(&dlm->spinlock);
1595 
1596                         mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
1597                         if (!mle) {
1598                                 response = DLM_MASTER_RESP_ERROR;
1599                                 mlog_errno(-ENOMEM);
1600                                 goto send_response;
1601                         }
1602                         goto way_up_top;
1603                 }
1604 
1605                 // mlog(0, "this is second time thru, already allocated, "
1606                 // "add the block.\n");
1607                 dlm_init_mle(mle, DLM_MLE_BLOCK, dlm, NULL, name, namelen);
1608                 set_bit(request->node_idx, mle->maybe_map);
1609                 __dlm_insert_mle(dlm, mle);
1610                 response = DLM_MASTER_RESP_NO;
1611         } else {
1612                 // mlog(0, "mle was found\n");
1613                 set_maybe = 1;
1614                 spin_lock(&tmpmle->spinlock);
1615                 if (tmpmle->master == dlm->node_num) {
1616                         mlog(ML_ERROR, "no lockres, but an mle with this node as master!\n");
1617                         BUG();
1618                 }
1619                 if (tmpmle->type == DLM_MLE_BLOCK)
1620                         response = DLM_MASTER_RESP_NO;
1621                 else if (tmpmle->type == DLM_MLE_MIGRATION) {
1622                         mlog(0, "migration mle was found (%u->%u)\n",
1623                              tmpmle->master, tmpmle->new_master);
1624                         /* real master can respond on its own */
1625                         response = DLM_MASTER_RESP_NO;
1626                 } else
1627                         response = DLM_MASTER_RESP_MAYBE;
1628                 if (set_maybe)
1629                         set_bit(request->node_idx, tmpmle->maybe_map);
1630                 spin_unlock(&tmpmle->spinlock);
1631         }
1632         spin_unlock(&dlm->master_lock);
1633         spin_unlock(&dlm->spinlock);
1634 
1635         if (found) {
1636                 /* keep the mle attached to heartbeat events */
1637                 dlm_put_mle(tmpmle);
1638         }
1639 send_response:
1640         /*
1641          * __dlm_lookup_lockres() grabbed a reference to this lockres.
1642          * The reference is released by dlm_assert_master_worker() under
1643          * the call to dlm_dispatch_assert_master().  If
1644          * dlm_assert_master_worker() isn't called, we drop it here.
1645          */
1646         if (dispatch_assert) {
1647                 if (response != DLM_MASTER_RESP_YES)
1648                         mlog(ML_ERROR, "invalid response %d\n", response);
1649                 if (!res) {
1650                         mlog(ML_ERROR, "bad lockres while trying to assert!\n");
1651                         BUG();
1652                 }
1653                 mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
1654                              dlm->node_num, res->lockname.len, res->lockname.name);
1655                 spin_lock(&res->spinlock);
1656                 ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx,
1657                                                  DLM_ASSERT_MASTER_MLE_CLEANUP);
1658                 if (ret < 0) {
1659                         mlog(ML_ERROR, "failed to dispatch assert master work\n");
1660                         response = DLM_MASTER_RESP_ERROR;
1661                         spin_unlock(&res->spinlock);
1662                         dlm_lockres_put(res);
1663                 } else {
1664                         dispatched = 1;
1665                         __dlm_lockres_grab_inflight_worker(dlm, res);
1666                         spin_unlock(&res->spinlock);
1667                 }
1668         } else {
1669                 if (res)
1670                         dlm_lockres_put(res);
1671         }
1672 
1673         if (!dispatched)
1674                 dlm_put(dlm);
1675         return response;
1676 }
1677 
1678 /*
1679  * DLM_ASSERT_MASTER_MSG
1680  */
1681 
1682 
1683 /*
1684  * NOTE: this can be used for debugging
1685  * can periodically run all locks owned by this node
1686  * and re-assert across the cluster...
1687  */
1688 static int dlm_do_assert_master(struct dlm_ctxt *dlm,
1689                                 struct dlm_lock_resource *res,
1690                                 void *nodemap, u32 flags)
1691 {
1692         struct dlm_assert_master assert;
1693         int to, tmpret;
1694         struct dlm_node_iter iter;
1695         int ret = 0;
1696         int reassert;
1697         const char *lockname = res->lockname.name;
1698         unsigned int namelen = res->lockname.len;
1699 
1700         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
1701 
1702         spin_lock(&res->spinlock);
1703         res->state |= DLM_LOCK_RES_SETREF_INPROG;
1704         spin_unlock(&res->spinlock);
1705 
1706 again:
1707         reassert = 0;
1708 
1709         /* note that if this nodemap is empty, it returns 0 */
1710         dlm_node_iter_init(nodemap, &iter);
1711         while ((to = dlm_node_iter_next(&iter)) >= 0) {
1712                 int r = 0;
1713                 struct dlm_master_list_entry *mle = NULL;
1714 
1715                 mlog(0, "sending assert master to %d (%.*s)\n", to,
1716                      namelen, lockname);
1717                 memset(&assert, 0, sizeof(assert));
1718                 assert.node_idx = dlm->node_num;
1719                 assert.namelen = namelen;
1720                 memcpy(assert.name, lockname, namelen);
1721                 assert.flags = cpu_to_be32(flags);
1722 
1723                 tmpret = o2net_send_message(DLM_ASSERT_MASTER_MSG, dlm->key,
1724                                             &assert, sizeof(assert), to, &r);
1725                 if (tmpret < 0) {
1726                         mlog(ML_ERROR, "Error %d when sending message %u (key "
1727                              "0x%x) to node %u\n", tmpret,
1728                              DLM_ASSERT_MASTER_MSG, dlm->key, to);
1729                         if (!dlm_is_host_down(tmpret)) {
1730                                 mlog(ML_ERROR, "unhandled error=%d!\n", tmpret);
1731                                 BUG();
1732                         }
1733                         /* a node died.  finish out the rest of the nodes. */
1734                         mlog(0, "link to %d went down!\n", to);
1735                         /* any nonzero status return will do */
1736                         ret = tmpret;
1737                         r = 0;
1738                 } else if (r < 0) {
1739                         /* ok, something horribly messed.  kill thyself. */
1740                         mlog(ML_ERROR,"during assert master of %.*s to %u, "
1741                              "got %d.\n", namelen, lockname, to, r);
1742                         spin_lock(&dlm->spinlock);
1743                         spin_lock(&dlm->master_lock);
1744                         if (dlm_find_mle(dlm, &mle, (char *)lockname,
1745                                          namelen)) {
1746                                 dlm_print_one_mle(mle);
1747                                 __dlm_put_mle(mle);
1748                         }
1749                         spin_unlock(&dlm->master_lock);
1750                         spin_unlock(&dlm->spinlock);
1751                         BUG();
1752                 }
1753 
1754                 if (r & DLM_ASSERT_RESPONSE_REASSERT &&
1755                     !(r & DLM_ASSERT_RESPONSE_MASTERY_REF)) {
1756                                 mlog(ML_ERROR, "%.*s: very strange, "
1757                                      "master MLE but no lockres on %u\n",
1758                                      namelen, lockname, to);
1759                 }
1760 
1761                 if (r & DLM_ASSERT_RESPONSE_REASSERT) {
1762                         mlog(0, "%.*s: node %u create mles on other "
1763                              "nodes and requests a re-assert\n",
1764                              namelen, lockname, to);
1765                         reassert = 1;
1766                 }
1767                 if (r & DLM_ASSERT_RESPONSE_MASTERY_REF) {
1768                         mlog(0, "%.*s: node %u has a reference to this "
1769                              "lockres, set the bit in the refmap\n",
1770                              namelen, lockname, to);
1771                         spin_lock(&res->spinlock);
1772                         dlm_lockres_set_refmap_bit(dlm, res, to);
1773                         spin_unlock(&res->spinlock);
1774                 }
1775         }
1776 
1777         if (reassert)
1778                 goto again;
1779 
1780         spin_lock(&res->spinlock);
1781         res->state &= ~DLM_LOCK_RES_SETREF_INPROG;
1782         spin_unlock(&res->spinlock);
1783         wake_up(&res->wq);
1784 
1785         return ret;
1786 }
1787 
1788 /*
1789  * locks that can be taken here:
1790  * dlm->spinlock
1791  * res->spinlock
1792  * mle->spinlock
1793  * dlm->master_list
1794  *
1795  * if possible, TRIM THIS DOWN!!!
1796  */
1797 int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data,
1798                               void **ret_data)
1799 {
1800         struct dlm_ctxt *dlm = data;
1801         struct dlm_master_list_entry *mle = NULL;
1802         struct dlm_assert_master *assert = (struct dlm_assert_master *)msg->buf;
1803         struct dlm_lock_resource *res = NULL;
1804         char *name;
1805         unsigned int namelen, hash;
1806         u32 flags;
1807         int master_request = 0, have_lockres_ref = 0;
1808         int ret = 0;
1809 
1810         if (!dlm_grab(dlm))
1811                 return 0;
1812 
1813         name = assert->name;
1814         namelen = assert->namelen;
1815         hash = dlm_lockid_hash(name, namelen);
1816         flags = be32_to_cpu(assert->flags);
1817 
1818         if (namelen > DLM_LOCKID_NAME_MAX) {
1819                 mlog(ML_ERROR, "Invalid name length!");
1820                 goto done;
1821         }
1822 
1823         spin_lock(&dlm->spinlock);
1824 
1825         if (flags)
1826                 mlog(0, "assert_master with flags: %u\n", flags);
1827 
1828         /* find the MLE */
1829         spin_lock(&dlm->master_lock);
1830         if (!dlm_find_mle(dlm, &mle, name, namelen)) {
1831                 /* not an error, could be master just re-asserting */
1832                 mlog(0, "just got an assert_master from %u, but no "
1833                      "MLE for it! (%.*s)\n", assert->node_idx,
1834                      namelen, name);
1835         } else {
1836                 int bit = find_next_bit (mle->maybe_map, O2NM_MAX_NODES, 0);
1837                 if (bit >= O2NM_MAX_NODES) {
1838                         /* not necessarily an error, though less likely.
1839                          * could be master just re-asserting. */
1840                         mlog(0, "no bits set in the maybe_map, but %u "
1841                              "is asserting! (%.*s)\n", assert->node_idx,
1842                              namelen, name);
1843                 } else if (bit != assert->node_idx) {
1844                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1845                                 mlog(0, "master %u was found, %u should "
1846                                      "back off\n", assert->node_idx, bit);
1847                         } else {
1848                                 /* with the fix for bug 569, a higher node
1849                                  * number winning the mastery will respond
1850                                  * YES to mastery requests, but this node
1851                                  * had no way of knowing.  let it pass. */
1852                                 mlog(0, "%u is the lowest node, "
1853                                      "%u is asserting. (%.*s)  %u must "
1854                                      "have begun after %u won.\n", bit,
1855                                      assert->node_idx, namelen, name, bit,
1856                                      assert->node_idx);
1857                         }
1858                 }
1859                 if (mle->type == DLM_MLE_MIGRATION) {
1860                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1861                                 mlog(0, "%s:%.*s: got cleanup assert"
1862                                      " from %u for migration\n",
1863                                      dlm->name, namelen, name,
1864                                      assert->node_idx);
1865                         } else if (!(flags & DLM_ASSERT_MASTER_FINISH_MIGRATION)) {
1866                                 mlog(0, "%s:%.*s: got unrelated assert"
1867                                      " from %u for migration, ignoring\n",
1868                                      dlm->name, namelen, name,
1869                                      assert->node_idx);
1870                                 __dlm_put_mle(mle);
1871                                 spin_unlock(&dlm->master_lock);
1872                                 spin_unlock(&dlm->spinlock);
1873                                 goto done;
1874                         }
1875                 }
1876         }
1877         spin_unlock(&dlm->master_lock);
1878 
1879         /* ok everything checks out with the MLE
1880          * now check to see if there is a lockres */
1881         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
1882         if (res) {
1883                 spin_lock(&res->spinlock);
1884                 if (res->state & DLM_LOCK_RES_RECOVERING)  {
1885                         mlog(ML_ERROR, "%u asserting but %.*s is "
1886                              "RECOVERING!\n", assert->node_idx, namelen, name);
1887                         goto kill;
1888                 }
1889                 if (!mle) {
1890                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN &&
1891                             res->owner != assert->node_idx) {
1892                                 mlog(ML_ERROR, "DIE! Mastery assert from %u, "
1893                                      "but current owner is %u! (%.*s)\n",
1894                                      assert->node_idx, res->owner, namelen,
1895                                      name);
1896                                 __dlm_print_one_lock_resource(res);
1897                                 BUG();
1898                         }
1899                 } else if (mle->type != DLM_MLE_MIGRATION) {
1900                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1901                                 /* owner is just re-asserting */
1902                                 if (res->owner == assert->node_idx) {
1903                                         mlog(0, "owner %u re-asserting on "
1904                                              "lock %.*s\n", assert->node_idx,
1905                                              namelen, name);
1906                                         goto ok;
1907                                 }
1908                                 mlog(ML_ERROR, "got assert_master from "
1909                                      "node %u, but %u is the owner! "
1910                                      "(%.*s)\n", assert->node_idx,
1911                                      res->owner, namelen, name);
1912                                 goto kill;
1913                         }
1914                         if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1915                                 mlog(ML_ERROR, "got assert from %u, but lock "
1916                                      "with no owner should be "
1917                                      "in-progress! (%.*s)\n",
1918                                      assert->node_idx,
1919                                      namelen, name);
1920                                 goto kill;
1921                         }
1922                 } else /* mle->type == DLM_MLE_MIGRATION */ {
1923                         /* should only be getting an assert from new master */
1924                         if (assert->node_idx != mle->new_master) {
1925                                 mlog(ML_ERROR, "got assert from %u, but "
1926                                      "new master is %u, and old master "
1927                                      "was %u (%.*s)\n",
1928                                      assert->node_idx, mle->new_master,
1929                                      mle->master, namelen, name);
1930                                 goto kill;
1931                         }
1932 
1933                 }
1934 ok:
1935                 spin_unlock(&res->spinlock);
1936         }
1937 
1938         // mlog(0, "woo!  got an assert_master from node %u!\n",
1939         //           assert->node_idx);
1940         if (mle) {
1941                 int extra_ref = 0;
1942                 int nn = -1;
1943                 int rr, err = 0;
1944 
1945                 spin_lock(&mle->spinlock);
1946                 if (mle->type == DLM_MLE_BLOCK || mle->type == DLM_MLE_MIGRATION)
1947                         extra_ref = 1;
1948                 else {
1949                         /* MASTER mle: if any bits set in the response map
1950                          * then the calling node needs to re-assert to clear
1951                          * up nodes that this node contacted */
1952                         while ((nn = find_next_bit (mle->response_map, O2NM_MAX_NODES,
1953                                                     nn+1)) < O2NM_MAX_NODES) {
1954                                 if (nn != dlm->node_num && nn != assert->node_idx) {
1955                                         master_request = 1;
1956                                         break;
1957                                 }
1958                         }
1959                 }
1960                 mle->master = assert->node_idx;
1961                 atomic_set(&mle->woken, 1);
1962                 wake_up(&mle->wq);
1963                 spin_unlock(&mle->spinlock);
1964 
1965                 if (res) {
1966                         int wake = 0;
1967                         spin_lock(&res->spinlock);
1968                         if (mle->type == DLM_MLE_MIGRATION) {
1969                                 mlog(0, "finishing off migration of lockres %.*s, "
1970                                         "from %u to %u\n",
1971                                         res->lockname.len, res->lockname.name,
1972                                         dlm->node_num, mle->new_master);
1973                                 res->state &= ~DLM_LOCK_RES_MIGRATING;
1974                                 wake = 1;
1975                                 dlm_change_lockres_owner(dlm, res, mle->new_master);
1976                                 BUG_ON(res->state & DLM_LOCK_RES_DIRTY);
1977                         } else {
1978                                 dlm_change_lockres_owner(dlm, res, mle->master);
1979                         }
1980                         spin_unlock(&res->spinlock);
1981                         have_lockres_ref = 1;
1982                         if (wake)
1983                                 wake_up(&res->wq);
1984                 }
1985 
1986                 /* master is known, detach if not already detached.
1987                  * ensures that only one assert_master call will happen
1988                  * on this mle. */
1989                 spin_lock(&dlm->master_lock);
1990 
1991                 rr = atomic_read(&mle->mle_refs.refcount);
1992                 if (mle->inuse > 0) {
1993                         if (extra_ref && rr < 3)
1994                                 err = 1;
1995                         else if (!extra_ref && rr < 2)
1996                                 err = 1;
1997                 } else {
1998                         if (extra_ref && rr < 2)
1999                                 err = 1;
2000                         else if (!extra_ref && rr < 1)
2001                                 err = 1;
2002                 }
2003                 if (err) {
2004                         mlog(ML_ERROR, "%s:%.*s: got assert master from %u "
2005                              "that will mess up this node, refs=%d, extra=%d, "
2006                              "inuse=%d\n", dlm->name, namelen, name,
2007                              assert->node_idx, rr, extra_ref, mle->inuse);
2008                         dlm_print_one_mle(mle);
2009                 }
2010                 __dlm_unlink_mle(dlm, mle);
2011                 __dlm_mle_detach_hb_events(dlm, mle);
2012                 __dlm_put_mle(mle);
2013                 if (extra_ref) {
2014                         /* the assert master message now balances the extra
2015                          * ref given by the master / migration request message.
2016                          * if this is the last put, it will be removed
2017                          * from the list. */
2018                         __dlm_put_mle(mle);
2019                 }
2020                 spin_unlock(&dlm->master_lock);
2021         } else if (res) {
2022                 if (res->owner != assert->node_idx) {
2023                         mlog(0, "assert_master from %u, but current "
2024                              "owner is %u (%.*s), no mle\n", assert->node_idx,
2025                              res->owner, namelen, name);
2026                 }
2027         }
2028         spin_unlock(&dlm->spinlock);
2029 
2030 done:
2031         ret = 0;
2032         if (res) {
2033                 spin_lock(&res->spinlock);
2034                 res->state |= DLM_LOCK_RES_SETREF_INPROG;
2035                 spin_unlock(&res->spinlock);
2036                 *ret_data = (void *)res;
2037         }
2038         dlm_put(dlm);
2039         if (master_request) {
2040                 mlog(0, "need to tell master to reassert\n");
2041                 /* positive. negative would shoot down the node. */
2042                 ret |= DLM_ASSERT_RESPONSE_REASSERT;
2043                 if (!have_lockres_ref) {
2044                         mlog(ML_ERROR, "strange, got assert from %u, MASTER "
2045                              "mle present here for %s:%.*s, but no lockres!\n",
2046                              assert->node_idx, dlm->name, namelen, name);
2047                 }
2048         }
2049         if (have_lockres_ref) {
2050                 /* let the master know we have a reference to the lockres */
2051                 ret |= DLM_ASSERT_RESPONSE_MASTERY_REF;
2052                 mlog(0, "%s:%.*s: got assert from %u, need a ref\n",
2053                      dlm->name, namelen, name, assert->node_idx);
2054         }
2055         return ret;
2056 
2057 kill:
2058         /* kill the caller! */
2059         mlog(ML_ERROR, "Bad message received from another node.  Dumping state "
2060              "and killing the other node now!  This node is OK and can continue.\n");
2061         __dlm_print_one_lock_resource(res);
2062         spin_unlock(&res->spinlock);
2063         spin_lock(&dlm->master_lock);
2064         if (mle)
2065                 __dlm_put_mle(mle);
2066         spin_unlock(&dlm->master_lock);
2067         spin_unlock(&dlm->spinlock);
2068         *ret_data = (void *)res;
2069         dlm_put(dlm);
2070         return -EINVAL;
2071 }
2072 
2073 void dlm_assert_master_post_handler(int status, void *data, void *ret_data)
2074 {
2075         struct dlm_lock_resource *res = (struct dlm_lock_resource *)ret_data;
2076 
2077         if (ret_data) {
2078                 spin_lock(&res->spinlock);
2079                 res->state &= ~DLM_LOCK_RES_SETREF_INPROG;
2080                 spin_unlock(&res->spinlock);
2081                 wake_up(&res->wq);
2082                 dlm_lockres_put(res);
2083         }
2084         return;
2085 }
2086 
2087 int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
2088                                struct dlm_lock_resource *res,
2089                                int ignore_higher, u8 request_from, u32 flags)
2090 {
2091         struct dlm_work_item *item;
2092         item = kzalloc(sizeof(*item), GFP_ATOMIC);
2093         if (!item)
2094                 return -ENOMEM;
2095 
2096 
2097         /* queue up work for dlm_assert_master_worker */
2098         dlm_init_work_item(dlm, item, dlm_assert_master_worker, NULL);
2099         item->u.am.lockres = res; /* already have a ref */
2100         /* can optionally ignore node numbers higher than this node */
2101         item->u.am.ignore_higher = ignore_higher;
2102         item->u.am.request_from = request_from;
2103         item->u.am.flags = flags;
2104 
2105         if (ignore_higher)
2106                 mlog(0, "IGNORE HIGHER: %.*s\n", res->lockname.len,
2107                      res->lockname.name);
2108 
2109         spin_lock(&dlm->work_lock);
2110         list_add_tail(&item->list, &dlm->work_list);
2111         spin_unlock(&dlm->work_lock);
2112 
2113         queue_work(dlm->dlm_worker, &dlm->dispatched_work);
2114         return 0;
2115 }
2116 
2117 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
2118 {
2119         struct dlm_ctxt *dlm = data;
2120         int ret = 0;
2121         struct dlm_lock_resource *res;
2122         unsigned long nodemap[BITS_TO_LONGS(O2NM_MAX_NODES)];
2123         int ignore_higher;
2124         int bit;
2125         u8 request_from;
2126         u32 flags;
2127 
2128         dlm = item->dlm;
2129         res = item->u.am.lockres;
2130         ignore_higher = item->u.am.ignore_higher;
2131         request_from = item->u.am.request_from;
2132         flags = item->u.am.flags;
2133 
2134         spin_lock(&dlm->spinlock);
2135         memcpy(nodemap, dlm->domain_map, sizeof(nodemap));
2136         spin_unlock(&dlm->spinlock);
2137 
2138         clear_bit(dlm->node_num, nodemap);
2139         if (ignore_higher) {
2140                 /* if is this just to clear up mles for nodes below
2141                  * this node, do not send the message to the original
2142                  * caller or any node number higher than this */
2143                 clear_bit(request_from, nodemap);
2144                 bit = dlm->node_num;
2145                 while (1) {
2146                         bit = find_next_bit(nodemap, O2NM_MAX_NODES,
2147                                             bit+1);
2148                         if (bit >= O2NM_MAX_NODES)
2149                                 break;
2150                         clear_bit(bit, nodemap);
2151                 }
2152         }
2153 
2154         /*
2155          * If we're migrating this lock to someone else, we are no
2156          * longer allowed to assert out own mastery.  OTOH, we need to
2157          * prevent migration from starting while we're still asserting
2158          * our dominance.  The reserved ast delays migration.
2159          */
2160         spin_lock(&res->spinlock);
2161         if (res->state & DLM_LOCK_RES_MIGRATING) {
2162                 mlog(0, "Someone asked us to assert mastery, but we're "
2163                      "in the middle of migration.  Skipping assert, "
2164                      "the new master will handle that.\n");
2165                 spin_unlock(&res->spinlock);
2166                 goto put;
2167         } else
2168                 __dlm_lockres_reserve_ast(res);
2169         spin_unlock(&res->spinlock);
2170 
2171         /* this call now finishes out the nodemap
2172          * even if one or more nodes die */
2173         mlog(0, "worker about to master %.*s here, this=%u\n",
2174                      res->lockname.len, res->lockname.name, dlm->node_num);
2175         ret = dlm_do_assert_master(dlm, res, nodemap, flags);
2176         if (ret < 0) {
2177                 /* no need to restart, we are done */
2178                 if (!dlm_is_host_down(ret))
2179                         mlog_errno(ret);
2180         }
2181 
2182         /* Ok, we've asserted ourselves.  Let's let migration start. */
2183         dlm_lockres_release_ast(dlm, res);
2184 
2185 put:
2186         dlm_lockres_drop_inflight_worker(dlm, res);
2187 
2188         dlm_lockres_put(res);
2189 
2190         mlog(0, "finished with dlm_assert_master_worker\n");
2191 }
2192 
2193 /* SPECIAL CASE for the $RECOVERY lock used by the recovery thread.
2194  * We cannot wait for node recovery to complete to begin mastering this
2195  * lockres because this lockres is used to kick off recovery! ;-)
2196  * So, do a pre-check on all living nodes to see if any of those nodes
2197  * think that $RECOVERY is currently mastered by a dead node.  If so,
2198  * we wait a short time to allow that node to get notified by its own
2199  * heartbeat stack, then check again.  All $RECOVERY lock resources
2200  * mastered by dead nodes are purged when the hearbeat callback is
2201  * fired, so we can know for sure that it is safe to continue once
2202  * the node returns a live node or no node.  */
2203 static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
2204                                        struct dlm_lock_resource *res)
2205 {
2206         struct dlm_node_iter iter;
2207         int nodenum;
2208         int ret = 0;
2209         u8 master = DLM_LOCK_RES_OWNER_UNKNOWN;
2210 
2211         spin_lock(&dlm->spinlock);
2212         dlm_node_iter_init(dlm->domain_map, &iter);
2213         spin_unlock(&dlm->spinlock);
2214 
2215         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
2216                 /* do not send to self */
2217                 if (nodenum == dlm->node_num)
2218                         continue;
2219                 ret = dlm_do_master_requery(dlm, res, nodenum, &master);
2220                 if (ret < 0) {
2221                         mlog_errno(ret);
2222                         if (!dlm_is_host_down(ret))
2223                                 BUG();
2224                         /* host is down, so answer for that node would be
2225                          * DLM_LOCK_RES_OWNER_UNKNOWN.  continue. */
2226                         ret = 0;
2227                 }
2228 
2229                 if (master != DLM_LOCK_RES_OWNER_UNKNOWN) {
2230                         /* check to see if this master is in the recovery map */
2231                         spin_lock(&dlm->spinlock);
2232                         if (test_bit(master, dlm->recovery_map)) {
2233                                 mlog(ML_NOTICE, "%s: node %u has not seen "
2234                                      "node %u go down yet, and thinks the "
2235                                      "dead node is mastering the recovery "
2236                                      "lock.  must wait.\n", dlm->name,
2237                                      nodenum, master);
2238                                 ret = -EAGAIN;
2239                         }
2240                         spin_unlock(&dlm->spinlock);
2241                         mlog(0, "%s: reco lock master is %u\n", dlm->name,
2242                              master);
2243                         break;
2244                 }
2245         }
2246         return ret;
2247 }
2248 
2249 /*
2250  * DLM_DEREF_LOCKRES_MSG
2251  */
2252 
2253 int dlm_drop_lockres_ref(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
2254 {
2255         struct dlm_deref_lockres deref;
2256         int ret = 0, r;
2257         const char *lockname;
2258         unsigned int namelen;
2259 
2260         lockname = res->lockname.name;
2261         namelen = res->lockname.len;
2262         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
2263 
2264         memset(&deref, 0, sizeof(deref));
2265         deref.node_idx = dlm->node_num;
2266         deref.namelen = namelen;
2267         memcpy(deref.name, lockname, namelen);
2268 
2269         ret = o2net_send_message(DLM_DEREF_LOCKRES_MSG, dlm->key,
2270                                  &deref, sizeof(deref), res->owner, &r);
2271         if (ret < 0)
2272                 mlog(ML_ERROR, "%s: res %.*s, error %d send DEREF to node %u\n",
2273                      dlm->name, namelen, lockname, ret, res->owner);
2274         else if (r < 0) {
2275                 /* BAD.  other node says I did not have a ref. */
2276                 mlog(ML_ERROR, "%s: res %.*s, DEREF to node %u got %d\n",
2277                      dlm->name, namelen, lockname, res->owner, r);
2278                 dlm_print_one_lock_resource(res);
2279                 BUG();
2280         }
2281         return ret;
2282 }
2283 
2284 int dlm_deref_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
2285                               void **ret_data)
2286 {
2287         struct dlm_ctxt *dlm = data;
2288         struct dlm_deref_lockres *deref = (struct dlm_deref_lockres *)msg->buf;
2289         struct dlm_lock_resource *res = NULL;
2290         char *name;
2291         unsigned int namelen;
2292         int ret = -EINVAL;
2293         u8 node;
2294         unsigned int hash;
2295         struct dlm_work_item *item;
2296         int cleared = 0;
2297         int dispatch = 0;
2298 
2299         if (!dlm_grab(dlm))
2300                 return 0;
2301 
2302         name = deref->name;
2303         namelen = deref->namelen;
2304         node = deref->node_idx;
2305 
2306         if (namelen > DLM_LOCKID_NAME_MAX) {
2307                 mlog(ML_ERROR, "Invalid name length!");
2308                 goto done;
2309         }
2310         if (deref->node_idx >= O2NM_MAX_NODES) {
2311                 mlog(ML_ERROR, "Invalid node number: %u\n", node);
2312                 goto done;
2313         }
2314 
2315         hash = dlm_lockid_hash(name, namelen);
2316 
2317         spin_lock(&dlm->spinlock);
2318         res = __dlm_lookup_lockres_full(dlm, name, namelen, hash);
2319         if (!res) {
2320                 spin_unlock(&dlm->spinlock);
2321                 mlog(ML_ERROR, "%s:%.*s: bad lockres name\n",
2322                      dlm->name, namelen, name);
2323                 goto done;
2324         }
2325         spin_unlock(&dlm->spinlock);
2326 
2327         spin_lock(&res->spinlock);
2328         if (res->state & DLM_LOCK_RES_SETREF_INPROG)
2329                 dispatch = 1;
2330         else {
2331                 BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
2332                 if (test_bit(node, res->refmap)) {
2333                         dlm_lockres_clear_refmap_bit(dlm, res, node);
2334                         cleared = 1;
2335                 }
2336         }
2337         spin_unlock(&res->spinlock);
2338 
2339         if (!dispatch) {
2340                 if (cleared)
2341                         dlm_lockres_calc_usage(dlm, res);
2342                 else {
2343                         mlog(ML_ERROR, "%s:%.*s: node %u trying to drop ref "
2344                         "but it is already dropped!\n", dlm->name,
2345                         res->lockname.len, res->lockname.name, node);
2346                         dlm_print_one_lock_resource(res);
2347                 }
2348                 ret = 0;
2349                 goto done;
2350         }
2351 
2352         item = kzalloc(sizeof(*item), GFP_NOFS);
2353         if (!item) {
2354                 ret = -ENOMEM;
2355                 mlog_errno(ret);
2356                 goto done;
2357         }
2358 
2359         dlm_init_work_item(dlm, item, dlm_deref_lockres_worker, NULL);
2360         item->u.dl.deref_res = res;
2361         item->u.dl.deref_node = node;
2362 
2363         spin_lock(&dlm->work_lock);
2364         list_add_tail(&item->list, &dlm->work_list);
2365         spin_unlock(&dlm->work_lock);
2366 
2367         queue_work(dlm->dlm_worker, &dlm->dispatched_work);
2368         return 0;
2369 
2370 done:
2371         if (res)
2372                 dlm_lockres_put(res);
2373         dlm_put(dlm);
2374 
2375         return ret;
2376 }
2377 
2378 static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data)
2379 {
2380         struct dlm_ctxt *dlm;
2381         struct dlm_lock_resource *res;
2382         u8 node;
2383         u8 cleared = 0;
2384 
2385         dlm = item->dlm;
2386         res = item->u.dl.deref_res;
2387         node = item->u.dl.deref_node;
2388 
2389         spin_lock(&res->spinlock);
2390         BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
2391         __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
2392         if (test_bit(node, res->refmap)) {
2393                 dlm_lockres_clear_refmap_bit(dlm, res, node);
2394                 cleared = 1;
2395         }
2396         spin_unlock(&res->spinlock);
2397 
2398         if (cleared) {
2399                 mlog(0, "%s:%.*s node %u ref dropped in dispatch\n",
2400                      dlm->name, res->lockname.len, res->lockname.name, node);
2401                 dlm_lockres_calc_usage(dlm, res);
2402         } else {
2403                 mlog(ML_ERROR, "%s:%.*s: node %u trying to drop ref "
2404                      "but it is already dropped!\n", dlm->name,
2405                      res->lockname.len, res->lockname.name, node);
2406                 dlm_print_one_lock_resource(res);
2407         }
2408 
2409         dlm_lockres_put(res);
2410 }
2411 
2412 /*
2413  * A migrateable resource is one that is :
2414  * 1. locally mastered, and,
2415  * 2. zero local locks, and,
2416  * 3. one or more non-local locks, or, one or more references
2417  * Returns 1 if yes, 0 if not.
2418  */
2419 static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm,
2420                                       struct dlm_lock_resource *res)
2421 {
2422         enum dlm_lockres_list idx;
2423         int nonlocal = 0, node_ref;
2424         struct list_head *queue;
2425         struct dlm_lock *lock;
2426         u64 cookie;
2427 
2428         assert_spin_locked(&res->spinlock);
2429 
2430         /* delay migration when the lockres is in MIGRATING state */
2431         if (res->state & DLM_LOCK_RES_MIGRATING)
2432                 return 0;
2433 
2434         /* delay migration when the lockres is in RECOCERING state */
2435         if (res->state & DLM_LOCK_RES_RECOVERING)
2436                 return 0;
2437 
2438         if (res->owner != dlm->node_num)
2439                 return 0;
2440 
2441         for (idx = DLM_GRANTED_LIST; idx <= DLM_BLOCKED_LIST; idx++) {
2442                 queue = dlm_list_idx_to_ptr(res, idx);
2443                 list_for_each_entry(lock, queue, list) {
2444                         if (lock->ml.node != dlm->node_num) {
2445                                 nonlocal++;
2446                                 continue;
2447                         }
2448                         cookie = be64_to_cpu(lock->ml.cookie);
2449                         mlog(0, "%s: Not migrateable res %.*s, lock %u:%llu on "
2450                              "%s list\n", dlm->name, res->lockname.len,
2451                              res->lockname.name,
2452                              dlm_get_lock_cookie_node(cookie),
2453                              dlm_get_lock_cookie_seq(cookie),
2454                              dlm_list_in_text(idx));
2455                         return 0;
2456                 }
2457         }
2458 
2459         if (!nonlocal) {
2460                 node_ref = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
2461                 if (node_ref >= O2NM_MAX_NODES)
2462                         return 0;
2463         }
2464 
2465         mlog(0, "%s: res %.*s, Migrateable\n", dlm->name, res->lockname.len,
2466              res->lockname.name);
2467 
2468         return 1;
2469 }
2470 
2471 /*
2472  * DLM_MIGRATE_LOCKRES
2473  */
2474 
2475 
2476 static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
2477                                struct dlm_lock_resource *res, u8 target)
2478 {
2479         struct dlm_master_list_entry *mle = NULL;
2480         struct dlm_master_list_entry *oldmle = NULL;
2481         struct dlm_migratable_lockres *mres = NULL;
2482         int ret = 0;
2483         const char *name;
2484         unsigned int namelen;
2485         int mle_added = 0;
2486         int wake = 0;
2487 
2488         if (!dlm_grab(dlm))
2489                 return -EINVAL;
2490 
2491         BUG_ON(target == O2NM_MAX_NODES);
2492 
2493         name = res->lockname.name;
2494         namelen = res->lockname.len;
2495 
2496         mlog(0, "%s: Migrating %.*s to node %u\n", dlm->name, namelen, name,
2497              target);
2498 
2499         /* preallocate up front. if this fails, abort */
2500         ret = -ENOMEM;
2501         mres = (struct dlm_migratable_lockres *) __get_free_page(GFP_NOFS);
2502         if (!mres) {
2503                 mlog_errno(ret);
2504                 goto leave;
2505         }
2506 
2507         mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
2508         if (!mle) {
2509                 mlog_errno(ret);
2510                 goto leave;
2511         }
2512         ret = 0;
2513 
2514         /*
2515          * clear any existing master requests and
2516          * add the migration mle to the list
2517          */
2518         spin_lock(&dlm->spinlock);
2519         spin_lock(&dlm->master_lock);
2520         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
2521                                     namelen, target, dlm->node_num);
2522         /* get an extra reference on the mle.
2523          * otherwise the assert_master from the new
2524          * master will destroy this.
2525          */
2526         dlm_get_mle_inuse(mle);
2527         spin_unlock(&dlm->master_lock);
2528         spin_unlock(&dlm->spinlock);
2529 
2530         if (ret == -EEXIST) {
2531                 mlog(0, "another process is already migrating it\n");
2532                 goto fail;
2533         }
2534         mle_added = 1;
2535 
2536         /*
2537          * set the MIGRATING flag and flush asts
2538          * if we fail after this we need to re-dirty the lockres
2539          */
2540         if (dlm_mark_lockres_migrating(dlm, res, target) < 0) {
2541                 mlog(ML_ERROR, "tried to migrate %.*s to %u, but "
2542                      "the target went down.\n", res->lockname.len,
2543                      res->lockname.name, target);
2544                 spin_lock(&res->spinlock);
2545                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2546                 wake = 1;
2547                 spin_unlock(&res->spinlock);
2548                 ret = -EINVAL;
2549         }
2550 
2551 fail:
2552         if (ret != -EEXIST && oldmle) {
2553                 /* master is known, detach if not already detached */
2554                 dlm_mle_detach_hb_events(dlm, oldmle);
2555                 dlm_put_mle(oldmle);
2556         }
2557 
2558         if (ret < 0) {
2559                 if (mle_added) {
2560                         dlm_mle_detach_hb_events(dlm, mle);
2561                         dlm_put_mle(mle);
2562                         dlm_put_mle_inuse(mle);
2563                 } else if (mle) {
2564                         kmem_cache_free(dlm_mle_cache, mle);
2565                         mle = NULL;
2566                 }
2567                 goto leave;
2568         }
2569 
2570         /*
2571          * at this point, we have a migration target, an mle
2572          * in the master list, and the MIGRATING flag set on
2573          * the lockres
2574          */
2575 
2576         /* now that remote nodes are spinning on the MIGRATING flag,
2577          * ensure that all assert_master work is flushed. */
2578         flush_workqueue(dlm->dlm_worker);
2579 
2580         /* notify new node and send all lock state */
2581         /* call send_one_lockres with migration flag.
2582          * this serves as notice to the target node that a
2583          * migration is starting. */
2584         ret = dlm_send_one_lockres(dlm, res, mres, target,
2585                                    DLM_MRES_MIGRATION);
2586 
2587         if (ret < 0) {
2588                 mlog(0, "migration to node %u failed with %d\n",
2589                      target, ret);
2590                 /* migration failed, detach and clean up mle */
2591                 dlm_mle_detach_hb_events(dlm, mle);
2592                 dlm_put_mle(mle);
2593                 dlm_put_mle_inuse(mle);
2594                 spin_lock(&res->spinlock);
2595                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2596                 wake = 1;
2597                 spin_unlock(&res->spinlock);
2598                 if (dlm_is_host_down(ret))
2599                         dlm_wait_for_node_death(dlm, target,
2600                                                 DLM_NODE_DEATH_WAIT_MAX);
2601                 goto leave;
2602         }
2603 
2604         /* at this point, the target sends a message to all nodes,
2605          * (using dlm_do_migrate_request).  this node is skipped since
2606          * we had to put an mle in the list to begin the process.  this
2607          * node now waits for target to do an assert master.  this node
2608          * will be the last one notified, ensuring that the migration
2609          * is complete everywhere.  if the target dies while this is
2610          * going on, some nodes could potentially see the target as the
2611          * master, so it is important that my recovery finds the migration
2612          * mle and sets the master to UNKNOWN. */
2613 
2614 
2615         /* wait for new node to assert master */
2616         while (1) {
2617                 ret = wait_event_interruptible_timeout(mle->wq,
2618                                         (atomic_read(&mle->woken) == 1),
2619                                         msecs_to_jiffies(5000));
2620 
2621                 if (ret >= 0) {
2622                         if (atomic_read(&mle->woken) == 1 ||
2623                             res->owner == target)
2624                                 break;
2625 
2626                         mlog(0, "%s:%.*s: timed out during migration\n",
2627                              dlm->name, res->lockname.len, res->lockname.name);
2628                         /* avoid hang during shutdown when migrating lockres
2629                          * to a node which also goes down */
2630                         if (dlm_is_node_dead(dlm, target)) {
2631                                 mlog(0, "%s:%.*s: expected migration "
2632                                      "target %u is no longer up, restarting\n",
2633                                      dlm->name, res->lockname.len,
2634                                      res->lockname.name, target);
2635                                 ret = -EINVAL;
2636                                 /* migration failed, detach and clean up mle */
2637                                 dlm_mle_detach_hb_events(dlm, mle);
2638                                 dlm_put_mle(mle);
2639                                 dlm_put_mle_inuse(mle);
2640                                 spin_lock(&res->spinlock);
2641                                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2642                                 wake = 1;
2643                                 spin_unlock(&res->spinlock);
2644                                 goto leave;
2645                         }
2646                 } else
2647                         mlog(0, "%s:%.*s: caught signal during migration\n",
2648                              dlm->name, res->lockname.len, res->lockname.name);
2649         }
2650 
2651         /* all done, set the owner, clear the flag */
2652         spin_lock(&res->spinlock);
2653         dlm_set_lockres_owner(dlm, res, target);
2654         res->state &= ~DLM_LOCK_RES_MIGRATING;
2655         dlm_remove_nonlocal_locks(dlm, res);
2656         spin_unlock(&res->spinlock);
2657         wake_up(&res->wq);
2658 
2659         /* master is known, detach if not already detached */
2660         dlm_mle_detach_hb_events(dlm, mle);
2661         dlm_put_mle_inuse(mle);
2662         ret = 0;
2663 
2664         dlm_lockres_calc_usage(dlm, res);
2665 
2666 leave:
2667         /* re-dirty the lockres if we failed */
2668         if (ret < 0)
2669                 dlm_kick_thread(dlm, res);
2670 
2671         /* wake up waiters if the MIGRATING flag got set
2672          * but migration failed */
2673         if (wake)
2674                 wake_up(&res->wq);
2675 
2676         if (mres)
2677                 free_page((unsigned long)mres);
2678 
2679         dlm_put(dlm);
2680 
2681         mlog(0, "%s: Migrating %.*s to %u, returns %d\n", dlm->name, namelen,
2682              name, target, ret);
2683         return ret;
2684 }
2685 
2686 #define DLM_MIGRATION_RETRY_MS  100
2687 
2688 /*
2689  * Should be called only after beginning the domain leave process.
2690  * There should not be any remaining locks on nonlocal lock resources,
2691  * and there should be no local locks left on locally mastered resources.
2692  *
2693  * Called with the dlm spinlock held, may drop it to do migration, but
2694  * will re-acquire before exit.
2695  *
2696  * Returns: 1 if dlm->spinlock was dropped/retaken, 0 if never dropped
2697  */
2698 int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
2699 {
2700         int ret;
2701         int lock_dropped = 0;
2702         u8 target = O2NM_MAX_NODES;
2703 
2704         assert_spin_locked(&dlm->spinlock);
2705 
2706         spin_lock(&res->spinlock);
2707         if (dlm_is_lockres_migrateable(dlm, res))
2708                 target = dlm_pick_migration_target(dlm, res);
2709         spin_unlock(&res->spinlock);
2710 
2711         if (target == O2NM_MAX_NODES)
2712                 goto leave;
2713 
2714         /* Wheee! Migrate lockres here! Will sleep so drop spinlock. */
2715         spin_unlock(&dlm->spinlock);
2716         lock_dropped = 1;
2717         ret = dlm_migrate_lockres(dlm, res, target);
2718         if (ret)
2719                 mlog(0, "%s: res %.*s, Migrate to node %u failed with %d\n",
2720                      dlm->name, res->lockname.len, res->lockname.name,
2721                      target, ret);
2722         spin_lock(&dlm->spinlock);
2723 leave:
2724         return lock_dropped;
2725 }
2726 
2727 int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock)
2728 {
2729         int ret;
2730         spin_lock(&dlm->ast_lock);
2731         spin_lock(&lock->spinlock);
2732         ret = (list_empty(&lock->bast_list) && !lock->bast_pending);
2733         spin_unlock(&lock->spinlock);
2734         spin_unlock(&dlm->ast_lock);
2735         return ret;
2736 }
2737 
2738 static int dlm_migration_can_proceed(struct dlm_ctxt *dlm,
2739                                      struct dlm_lock_resource *res,
2740                                      u8 mig_target)
2741 {
2742         int can_proceed;
2743         spin_lock(&res->spinlock);
2744         can_proceed = !!(res->state & DLM_LOCK_RES_MIGRATING);
2745         spin_unlock(&res->spinlock);
2746 
2747         /* target has died, so make the caller break out of the
2748          * wait_event, but caller must recheck the domain_map */
2749         spin_lock(&dlm->spinlock);
2750         if (!test_bit(mig_target, dlm->domain_map))
2751                 can_proceed = 1;
2752         spin_unlock(&dlm->spinlock);
2753         return can_proceed;
2754 }
2755 
2756 static int dlm_lockres_is_dirty(struct dlm_ctxt *dlm,
2757                                 struct dlm_lock_resource *res)
2758 {
2759         int ret;
2760         spin_lock(&res->spinlock);
2761         ret = !!(res->state & DLM_LOCK_RES_DIRTY);
2762         spin_unlock(&res->spinlock);
2763         return ret;
2764 }
2765 
2766 
2767 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
2768                                        struct dlm_lock_resource *res,
2769                                        u8 target)
2770 {
2771         int ret = 0;
2772 
2773         mlog(0, "dlm_mark_lockres_migrating: %.*s, from %u to %u\n",
2774                res->lockname.len, res->lockname.name, dlm->node_num,
2775                target);
2776         /* need to set MIGRATING flag on lockres.  this is done by
2777          * ensuring that all asts have been flushed for this lockres. */
2778         spin_lock(&res->spinlock);
2779         BUG_ON(res->migration_pending);
2780         res->migration_pending = 1;
2781         /* strategy is to reserve an extra ast then release
2782          * it below, letting the release do all of the work */
2783         __dlm_lockres_reserve_ast(res);
2784         spin_unlock(&res->spinlock);
2785 
2786         /* now flush all the pending asts */
2787         dlm_kick_thread(dlm, res);
2788         /* before waiting on DIRTY, block processes which may
2789          * try to dirty the lockres before MIGRATING is set */
2790         spin_lock(&res->spinlock);
2791         BUG_ON(res->state & DLM_LOCK_RES_BLOCK_DIRTY);
2792         res->state |= DLM_LOCK_RES_BLOCK_DIRTY;
2793         spin_unlock(&res->spinlock);
2794         /* now wait on any pending asts and the DIRTY state */
2795         wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
2796         dlm_lockres_release_ast(dlm, res);
2797 
2798         mlog(0, "about to wait on migration_wq, dirty=%s\n",
2799                res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
2800         /* if the extra ref we just put was the final one, this
2801          * will pass thru immediately.  otherwise, we need to wait
2802          * for the last ast to finish. */
2803 again:
2804         ret = wait_event_interruptible_timeout(dlm->migration_wq,
2805                    dlm_migration_can_proceed(dlm, res, target),
2806                    msecs_to_jiffies(1000));
2807         if (ret < 0) {
2808                 mlog(0, "woken again: migrating? %s, dead? %s\n",
2809                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2810                        test_bit(target, dlm->domain_map) ? "no":"yes");
2811         } else {
2812                 mlog(0, "all is well: migrating? %s, dead? %s\n",
2813                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2814                        test_bit(target, dlm->domain_map) ? "no":"yes");
2815         }
2816         if (!dlm_migration_can_proceed(dlm, res, target)) {
2817                 mlog(0, "trying again...\n");
2818                 goto again;
2819         }
2820 
2821         ret = 0;
2822         /* did the target go down or die? */
2823         spin_lock(&dlm->spinlock);
2824         if (!test_bit(target, dlm->domain_map)) {
2825                 mlog(ML_ERROR, "aha. migration target %u just went down\n",
2826                      target);
2827                 ret = -EHOSTDOWN;
2828         }
2829         spin_unlock(&dlm->spinlock);
2830 
2831         /*
2832          * if target is down, we need to clear DLM_LOCK_RES_BLOCK_DIRTY for
2833          * another try; otherwise, we are sure the MIGRATING state is there,
2834          * drop the unneded state which blocked threads trying to DIRTY
2835          */
2836         spin_lock(&res->spinlock);
2837         BUG_ON(!(res->state & DLM_LOCK_RES_BLOCK_DIRTY));
2838         res->state &= ~DLM_LOCK_RES_BLOCK_DIRTY;
2839         if (!ret)
2840                 BUG_ON(!(res->state & DLM_LOCK_RES_MIGRATING));
2841         else
2842                 res->migration_pending = 0;
2843         spin_unlock(&res->spinlock);
2844 
2845         /*
2846          * at this point:
2847          *
2848          *   o the DLM_LOCK_RES_MIGRATING flag is set if target not down
2849          *   o there are no pending asts on this lockres
2850          *   o all processes trying to reserve an ast on this
2851          *     lockres must wait for the MIGRATING flag to clear
2852          */
2853         return ret;
2854 }
2855 
2856 /* last step in the migration process.
2857  * original master calls this to free all of the dlm_lock
2858  * structures that used to be for other nodes. */
2859 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
2860                                       struct dlm_lock_resource *res)
2861 {
2862         struct list_head *queue = &res->granted;
2863         int i, bit;
2864         struct dlm_lock *lock, *next;
2865 
2866         assert_spin_locked(&res->spinlock);
2867 
2868         BUG_ON(res->owner == dlm->node_num);
2869 
2870         for (i=0; i<3; i++) {
2871                 list_for_each_entry_safe(lock, next, queue, list) {
2872                         if (lock->ml.node != dlm->node_num) {
2873                                 mlog(0, "putting lock for node %u\n",
2874                                      lock->ml.node);
2875                                 /* be extra careful */
2876                                 BUG_ON(!list_empty(&lock->ast_list));
2877                                 BUG_ON(!list_empty(&lock->bast_list));
2878                                 BUG_ON(lock->ast_pending);
2879                                 BUG_ON(lock->bast_pending);
2880                                 dlm_lockres_clear_refmap_bit(dlm, res,
2881                                                              lock->ml.node);
2882                                 list_del_init(&lock->list);
2883                                 dlm_lock_put(lock);
2884                                 /* In a normal unlock, we would have added a
2885                                  * DLM_UNLOCK_FREE_LOCK action. Force it. */
2886                                 dlm_lock_put(lock);
2887                         }
2888                 }
2889                 queue++;
2890         }
2891         bit = 0;
2892         while (1) {
2893                 bit = find_next_bit(res->refmap, O2NM_MAX_NODES, bit);
2894                 if (bit >= O2NM_MAX_NODES)
2895                         break;
2896                 /* do not clear the local node reference, if there is a
2897                  * process holding this, let it drop the ref itself */
2898                 if (bit != dlm->node_num) {
2899                         mlog(0, "%s:%.*s: node %u had a ref to this "
2900                              "migrating lockres, clearing\n", dlm->name,
2901                              res->lockname.len, res->lockname.name, bit);
2902                         dlm_lockres_clear_refmap_bit(dlm, res, bit);
2903                 }
2904                 bit++;
2905         }
2906 }
2907 
2908 /*
2909  * Pick a node to migrate the lock resource to. This function selects a
2910  * potential target based first on the locks and then on refmap. It skips
2911  * nodes that are in the process of exiting the domain.
2912  */
2913 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
2914                                     struct dlm_lock_resource *res)
2915 {
2916         enum dlm_lockres_list idx;
2917         struct list_head *queue = &res->granted;
2918         struct dlm_lock *lock;
2919         int noderef;
2920         u8 nodenum = O2NM_MAX_NODES;
2921 
2922         assert_spin_locked(&dlm->spinlock);
2923         assert_spin_locked(&res->spinlock);
2924 
2925         /* Go through all the locks */
2926         for (idx = DLM_GRANTED_LIST; idx <= DLM_BLOCKED_LIST; idx++) {
2927                 queue = dlm_list_idx_to_ptr(res, idx);
2928                 list_for_each_entry(lock, queue, list) {
2929                         if (lock->ml.node == dlm->node_num)
2930                                 continue;
2931                         if (test_bit(lock->ml.node, dlm->exit_domain_map))
2932                                 continue;
2933                         nodenum = lock->ml.node;
2934                         goto bail;
2935                 }
2936         }
2937 
2938         /* Go thru the refmap */
2939         noderef = -1;
2940         while (1) {
2941                 noderef = find_next_bit(res->refmap, O2NM_MAX_NODES,
2942                                         noderef + 1);
2943                 if (noderef >= O2NM_MAX_NODES)
2944                         break;
2945                 if (noderef == dlm->node_num)
2946                         continue;
2947                 if (test_bit(noderef, dlm->exit_domain_map))
2948                         continue;
2949                 nodenum = noderef;
2950                 goto bail;
2951         }
2952 
2953 bail:
2954         return nodenum;
2955 }
2956 
2957 /* this is called by the new master once all lockres
2958  * data has been received */
2959 static int dlm_do_migrate_request(struct dlm_ctxt *dlm,
2960                                   struct dlm_lock_resource *res,
2961                                   u8 master, u8 new_master,
2962                                   struct dlm_node_iter *iter)
2963 {
2964         struct dlm_migrate_request migrate;
2965         int ret, skip, status = 0;
2966         int nodenum;
2967 
2968         memset(&migrate, 0, sizeof(migrate));
2969         migrate.namelen = res->lockname.len;
2970         memcpy(migrate.name, res->lockname.name, migrate.namelen);
2971         migrate.new_master = new_master;
2972         migrate.master = master;
2973 
2974         ret = 0;
2975 
2976         /* send message to all nodes, except the master and myself */
2977         while ((nodenum = dlm_node_iter_next(iter)) >= 0) {
2978                 if (nodenum == master ||
2979                     nodenum == new_master)
2980                         continue;
2981 
2982                 /* We could race exit domain. If exited, skip. */
2983                 spin_lock(&dlm->spinlock);
2984                 skip = (!test_bit(nodenum, dlm->domain_map));
2985                 spin_unlock(&dlm->spinlock);
2986                 if (skip) {
2987                         clear_bit(nodenum, iter->node_map);
2988                         continue;
2989                 }
2990 
2991                 ret = o2net_send_message(DLM_MIGRATE_REQUEST_MSG, dlm->key,
2992                                          &migrate, sizeof(migrate), nodenum,
2993                                          &status);
2994                 if (ret < 0) {
2995                         mlog(ML_ERROR, "%s: res %.*s, Error %d send "
2996                              "MIGRATE_REQUEST to node %u\n", dlm->name,
2997                              migrate.namelen, migrate.name, ret, nodenum);
2998                         if (!dlm_is_host_down(ret)) {
2999                                 mlog(ML_ERROR, "unhandled error=%d!\n", ret);
3000                                 BUG();
3001                         }
3002                         clear_bit(nodenum, iter->node_map);
3003                         ret = 0;
3004                 } else if (status < 0) {
3005                         mlog(0, "migrate request (node %u) returned %d!\n",
3006                              nodenum, status);
3007                         ret = status;
3008                 } else if (status == DLM_MIGRATE_RESPONSE_MASTERY_REF) {
3009                         /* during the migration request we short-circuited
3010                          * the mastery of the lockres.  make sure we have
3011                          * a mastery ref for nodenum */
3012                         mlog(0, "%s:%.*s: need ref for node %u\n",
3013                              dlm->name, res->lockname.len, res->lockname.name,
3014                              nodenum);
3015                         spin_lock(&res->spinlock);
3016                         dlm_lockres_set_refmap_bit(dlm, res, nodenum);
3017                         spin_unlock(&res->spinlock);
3018                 }
3019         }
3020 
3021         if (ret < 0)
3022                 mlog_errno(ret);
3023 
3024         mlog(0, "returning ret=%d\n", ret);
3025         return ret;
3026 }
3027 
3028 
3029 /* if there is an existing mle for this lockres, we now know who the master is.
3030  * (the one who sent us *this* message) we can clear it up right away.
3031  * since the process that put the mle on the list still has a reference to it,
3032  * we can unhash it now, set the master and wake the process.  as a result,
3033  * we will have no mle in the list to start with.  now we can add an mle for
3034  * the migration and this should be the only one found for those scanning the
3035  * list.  */
3036 int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
3037                                 void **ret_data)
3038 {
3039         struct dlm_ctxt *dlm = data;
3040         struct dlm_lock_resource *res = NULL;
3041         struct dlm_migrate_request *migrate = (struct dlm_migrate_request *) msg->buf;
3042         struct dlm_master_list_entry *mle = NULL, *oldmle = NULL;
3043         const char *name;
3044         unsigned int namelen, hash;
3045         int ret = 0;
3046 
3047         if (!dlm_grab(dlm))
3048                 return 0;
3049 
3050         name = migrate->name;
3051         namelen = migrate->namelen;
3052         hash = dlm_lockid_hash(name, namelen);
3053 
3054         /* preallocate.. if this fails, abort */
3055         mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
3056 
3057         if (!mle) {
3058                 ret = -ENOMEM;
3059                 goto leave;
3060         }
3061 
3062         /* check for pre-existing lock */
3063         spin_lock(&dlm->spinlock);
3064         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
3065         if (res) {
3066                 spin_lock(&res->spinlock);
3067                 if (res->state & DLM_LOCK_RES_RECOVERING) {
3068                         /* if all is working ok, this can only mean that we got
3069                         * a migrate request from a node that we now see as
3070                         * dead.  what can we do here?  drop it to the floor? */
3071                         spin_unlock(&res->spinlock);
3072                         mlog(ML_ERROR, "Got a migrate request, but the "
3073                              "lockres is marked as recovering!");
3074                         kmem_cache_free(dlm_mle_cache, mle);
3075                         ret = -EINVAL; /* need a better solution */
3076                         goto unlock;
3077                 }
3078                 res->state |= DLM_LOCK_RES_MIGRATING;
3079                 spin_unlock(&res->spinlock);
3080         }
3081 
3082         spin_lock(&dlm->master_lock);
3083         /* ignore status.  only nonzero status would BUG. */
3084         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
3085                                     name, namelen,
3086                                     migrate->new_master,
3087                                     migrate->master);
3088 
3089         spin_unlock(&dlm->master_lock);
3090 unlock:
3091         spin_unlock(&dlm->spinlock);
3092 
3093         if (oldmle) {
3094                 /* master is known, detach if not already detached */
3095                 dlm_mle_detach_hb_events(dlm, oldmle);
3096                 dlm_put_mle(oldmle);
3097         }
3098 
3099         if (res)
3100                 dlm_lockres_put(res);
3101 leave:
3102         dlm_put(dlm);
3103         return ret;
3104 }
3105 
3106 /* must be holding dlm->spinlock and dlm->master_lock
3107  * when adding a migration mle, we can clear any other mles
3108  * in the master list because we know with certainty that
3109  * the master is "master".  so we remove any old mle from
3110  * the list after setting it's master field, and then add
3111  * the new migration mle.  this way we can hold with the rule
3112  * of having only one mle for a given lock name at all times. */
3113 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
3114                                  struct dlm_lock_resource *res,
3115                                  struct dlm_master_list_entry *mle,
3116                                  struct dlm_master_list_entry **oldmle,
3117                                  const char *name, unsigned int namelen,
3118                                  u8 new_master, u8 master)
3119 {
3120         int found;
3121         int ret = 0;
3122 
3123         *oldmle = NULL;
3124 
3125         assert_spin_locked(&dlm->spinlock);
3126         assert_spin_locked(&dlm->master_lock);
3127 
3128         /* caller is responsible for any ref taken here on oldmle */
3129         found = dlm_find_mle(dlm, oldmle, (char *)name, namelen);
3130         if (found) {
3131                 struct dlm_master_list_entry *tmp = *oldmle;
3132                 spin_lock(&tmp->spinlock);
3133                 if (tmp->type == DLM_MLE_MIGRATION) {
3134                         if (master == dlm->node_num) {
3135                                 /* ah another process raced me to it */
3136                                 mlog(0, "tried to migrate %.*s, but some "
3137                                      "process beat me to it\n",
3138                                      namelen, name);
3139                                 spin_unlock(&tmp->spinlock);
3140                                 return -EEXIST;
3141                         } else {
3142                                 /* bad.  2 NODES are trying to migrate! */
3143                                 mlog(ML_ERROR, "migration error  mle: "
3144                                      "master=%u new_master=%u // request: "
3145                                      "master=%u new_master=%u // "
3146                                      "lockres=%.*s\n",
3147                                      tmp->master, tmp->new_master,
3148                                      master, new_master,
3149                                      namelen, name);
3150                                 BUG();
3151                         }
3152                 } else {
3153                         /* this is essentially what assert_master does */
3154                         tmp->master = master;
3155                         atomic_set(&tmp->woken, 1);
3156                         wake_up(&tmp->wq);
3157                         /* remove it so that only one mle will be found */
3158                         __dlm_unlink_mle(dlm, tmp);
3159                         __dlm_mle_detach_hb_events(dlm, tmp);
3160                         if (tmp->type == DLM_MLE_MASTER) {
3161                                 ret = DLM_MIGRATE_RESPONSE_MASTERY_REF;
3162                                 mlog(0, "%s:%.*s: master=%u, newmaster=%u, "
3163                                                 "telling master to get ref "
3164                                                 "for cleared out mle during "
3165                                                 "migration\n", dlm->name,
3166                                                 namelen, name, master,
3167                                                 new_master);
3168                         }
3169                 }
3170                 spin_unlock(&tmp->spinlock);
3171         }
3172 
3173         /* now add a migration mle to the tail of the list */
3174         dlm_init_mle(mle, DLM_MLE_MIGRATION, dlm, res, name, namelen);
3175         mle->new_master = new_master;
3176         /* the new master will be sending an assert master for this.
3177          * at that point we will get the refmap reference */
3178         mle->master = master;
3179         /* do this for consistency with other mle types */
3180         set_bit(new_master, mle->maybe_map);
3181         __dlm_insert_mle(dlm, mle);
3182 
3183         return ret;
3184 }
3185 
3186 /*
3187  * Sets the owner of the lockres, associated to the mle, to UNKNOWN
3188  */
3189 static struct dlm_lock_resource *dlm_reset_mleres_owner(struct dlm_ctxt *dlm,
3190                                         struct dlm_master_list_entry *mle)
3191 {
3192         struct dlm_lock_resource *res;
3193 
3194         /* Find the lockres associated to the mle and set its owner to UNK */
3195         res = __dlm_lookup_lockres(dlm, mle->mname, mle->mnamelen,
3196                                    mle->mnamehash);
3197         if (res) {
3198                 spin_unlock(&dlm->master_lock);
3199 
3200                 /* move lockres onto recovery list */
3201                 spin_lock(&res->spinlock);
3202                 dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
3203                 dlm_move_lockres_to_recovery_list(dlm, res);
3204                 spin_unlock(&res->spinlock);
3205                 dlm_lockres_put(res);
3206 
3207                 /* about to get rid of mle, detach from heartbeat */
3208                 __dlm_mle_detach_hb_events(dlm, mle);
3209 
3210                 /* dump the mle */
3211                 spin_lock(&dlm->master_lock);
3212                 __dlm_put_mle(mle);
3213                 spin_unlock(&dlm->master_lock);
3214         }
3215 
3216         return res;
3217 }
3218 
3219 static void dlm_clean_migration_mle(struct dlm_ctxt *dlm,
3220                                     struct dlm_master_list_entry *mle)
3221 {
3222         __dlm_mle_detach_hb_events(dlm, mle);
3223 
3224         spin_lock(&mle->spinlock);
3225         __dlm_unlink_mle(dlm, mle);
3226         atomic_set(&mle->woken, 1);
3227         spin_unlock(&mle->spinlock);
3228 
3229         wake_up(&mle->wq);
3230 }
3231 
3232 static void dlm_clean_block_mle(struct dlm_ctxt *dlm,
3233                                 struct dlm_master_list_entry *mle, u8 dead_node)
3234 {
3235         int bit;
3236 
3237         BUG_ON(mle->type != DLM_MLE_BLOCK);
3238 
3239         spin_lock(&mle->spinlock);
3240         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
3241         if (bit != dead_node) {
3242                 mlog(0, "mle found, but dead node %u would not have been "
3243                      "master\n", dead_node);
3244                 spin_unlock(&mle->spinlock);
3245         } else {
3246                 /* Must drop the refcount by one since the assert_master will
3247                  * never arrive. This may result in the mle being unlinked and
3248                  * freed, but there may still be a process waiting in the
3249                  * dlmlock path which is fine. */
3250                 mlog(0, "node %u was expected master\n", dead_node);
3251                 atomic_set(&mle->woken, 1);
3252                 spin_unlock(&mle->spinlock);
3253                 wake_up(&mle->wq);
3254 
3255                 /* Do not need events any longer, so detach from heartbeat */
3256                 __dlm_mle_detach_hb_events(dlm, mle);
3257                 __dlm_put_mle(mle);
3258         }
3259 }
3260 
3261 void dlm_clean_master_list(struct dlm_ctxt *dlm, u8 dead_node)
3262 {
3263         struct dlm_master_list_entry *mle;
3264         struct dlm_lock_resource *res;
3265         struct hlist_head *bucket;
3266         struct hlist_node *tmp;
3267         unsigned int i;
3268 
3269         mlog(0, "dlm=%s, dead node=%u\n", dlm->name, dead_node);
3270 top:
3271         assert_spin_locked(&dlm->spinlock);
3272 
3273         /* clean the master list */
3274         spin_lock(&dlm->master_lock);
3275         for (i = 0; i < DLM_HASH_BUCKETS; i++) {
3276                 bucket = dlm_master_hash(dlm, i);
3277                 hlist_for_each_entry_safe(mle, tmp, bucket, master_hash_node) {
3278                         BUG_ON(mle->type != DLM_MLE_BLOCK &&
3279                                mle->type != DLM_MLE_MASTER &&
3280                                mle->type != DLM_MLE_MIGRATION);
3281 
3282                         /* MASTER mles are initiated locally. The waiting
3283                          * process will notice the node map change shortly.
3284                          * Let that happen as normal. */
3285                         if (mle->type == DLM_MLE_MASTER)
3286                                 continue;
3287 
3288                         /* BLOCK mles are initiated by other nodes. Need to
3289                          * clean up if the dead node would have been the
3290                          * master. */
3291                         if (mle->type == DLM_MLE_BLOCK) {
3292                                 dlm_clean_block_mle(dlm, mle, dead_node);
3293                                 continue;
3294                         }
3295 
3296                         /* Everything else is a MIGRATION mle */
3297 
3298                         /* The rule for MIGRATION mles is that the master
3299                          * becomes UNKNOWN if *either* the original or the new
3300                          * master dies. All UNKNOWN lockres' are sent to
3301                          * whichever node becomes the recovery master. The new
3302                          * master is responsible for determining if there is
3303                          * still a master for this lockres, or if he needs to
3304                          * take over mastery. Either way, this node should
3305                          * expect another message to resolve this. */
3306 
3307                         if (mle->master != dead_node &&
3308                             mle->new_master != dead_node)
3309                                 continue;
3310 
3311                         if (mle->new_master == dead_node && mle->inuse) {
3312                                 mlog(ML_NOTICE, "%s: target %u died during "
3313                                                 "migration from %u, the MLE is "
3314                                                 "still keep used, ignore it!\n",
3315                                                 dlm->name, dead_node,
3316                                                 mle->master);
3317                                 continue;
3318                         }
3319 
3320                         /* If we have reached this point, this mle needs to be
3321                          * removed from the list and freed. */
3322                         dlm_clean_migration_mle(dlm, mle);
3323 
3324                         mlog(0, "%s: node %u died during migration from "
3325                              "%u to %u!\n", dlm->name, dead_node, mle->master,
3326                              mle->new_master);
3327 
3328                         /* If we find a lockres associated with the mle, we've
3329                          * hit this rare case that messes up our lock ordering.
3330                          * If so, we need to drop the master lock so that we can
3331                          * take the lockres lock, meaning that we will have to
3332                          * restart from the head of list. */
3333                         res = dlm_reset_mleres_owner(dlm, mle);
3334                         if (res)
3335                                 /* restart */
3336                                 goto top;
3337 
3338                         /* This may be the last reference */
3339                         __dlm_put_mle(mle);
3340                 }
3341         }
3342         spin_unlock(&dlm->master_lock);
3343 }
3344 
3345 int dlm_finish_migration(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
3346                          u8 old_master)
3347 {
3348         struct dlm_node_iter iter;
3349         int ret = 0;
3350 
3351         spin_lock(&dlm->spinlock);
3352         dlm_node_iter_init(dlm->domain_map, &iter);
3353         clear_bit(old_master, iter.node_map);
3354         clear_bit(dlm->node_num, iter.node_map);
3355         spin_unlock(&dlm->spinlock);
3356 
3357         /* ownership of the lockres is changing.  account for the
3358          * mastery reference here since old_master will briefly have
3359          * a reference after the migration completes */
3360         spin_lock(&res->spinlock);
3361         dlm_lockres_set_refmap_bit(dlm, res, old_master);
3362         spin_unlock(&res->spinlock);
3363 
3364         mlog(0, "now time to do a migrate request to other nodes\n");
3365         ret = dlm_do_migrate_request(dlm, res, old_master,
3366                                      dlm->node_num, &iter);
3367         if (ret < 0) {
3368                 mlog_errno(ret);
3369                 goto leave;
3370         }
3371 
3372         mlog(0, "doing assert master of %.*s to all except the original node\n",
3373              res->lockname.len, res->lockname.name);
3374         /* this call now finishes out the nodemap
3375          * even if one or more nodes die */
3376         ret = dlm_do_assert_master(dlm, res, iter.node_map,
3377                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
3378         if (ret < 0) {
3379                 /* no longer need to retry.  all living nodes contacted. */
3380                 mlog_errno(ret);
3381                 ret = 0;
3382         }
3383 
3384         memset(iter.node_map, 0, sizeof(iter.node_map));
3385         set_bit(old_master, iter.node_map);
3386         mlog(0, "doing assert master of %.*s back to %u\n",
3387              res->lockname.len, res->lockname.name, old_master);
3388         ret = dlm_do_assert_master(dlm, res, iter.node_map,
3389                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
3390         if (ret < 0) {
3391                 mlog(0, "assert master to original master failed "
3392                      "with %d.\n", ret);
3393                 /* the only nonzero status here would be because of
3394                  * a dead original node.  we're done. */
3395                 ret = 0;
3396         }
3397 
3398         /* all done, set the owner, clear the flag */
3399         spin_lock(&res->spinlock);
3400         dlm_set_lockres_owner(dlm, res, dlm->node_num);
3401         res->state &= ~DLM_LOCK_RES_MIGRATING;
3402         spin_unlock(&res->spinlock);
3403         /* re-dirty it on the new master */
3404         dlm_kick_thread(dlm, res);
3405         wake_up(&res->wq);
3406 leave:
3407         return ret;
3408 }
3409 
3410 /*
3411  * LOCKRES AST REFCOUNT
3412  * this is integral to migration
3413  */
3414 
3415 /* for future intent to call an ast, reserve one ahead of time.
3416  * this should be called only after waiting on the lockres
3417  * with dlm_wait_on_lockres, and while still holding the
3418  * spinlock after the call. */
3419 void __dlm_lockres_reserve_ast(struct dlm_lock_resource *res)
3420 {
3421         assert_spin_locked(&res->spinlock);
3422         if (res->state & DLM_LOCK_RES_MIGRATING) {
3423                 __dlm_print_one_lock_resource(res);
3424         }
3425         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
3426 
3427         atomic_inc(&res->asts_reserved);
3428 }
3429 
3430 /*
3431  * used to drop the reserved ast, either because it went unused,
3432  * or because the ast/bast was actually called.
3433  *
3434  * also, if there is a pending migration on this lockres,
3435  * and this was the last pending ast on the lockres,
3436  * atomically set the MIGRATING flag before we drop the lock.
3437  * this is how we ensure that migration can proceed with no
3438  * asts in progress.  note that it is ok if the state of the
3439  * queues is such that a lock should be granted in the future
3440  * or that a bast should be fired, because the new master will
3441  * shuffle the lists on this lockres as soon as it is migrated.
3442  */
3443 void dlm_lockres_release_ast(struct dlm_ctxt *dlm,
3444                              struct dlm_lock_resource *res)
3445 {
3446         if (!atomic_dec_and_lock(&res->asts_reserved, &res->spinlock))
3447                 return;
3448 
3449         if (!res->migration_pending) {
3450                 spin_unlock(&res->spinlock);
3451                 return;
3452         }
3453 
3454         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
3455         res->migration_pending = 0;
3456         res->state |= DLM_LOCK_RES_MIGRATING;
3457         spin_unlock(&res->spinlock);
3458         wake_up(&res->wq);
3459         wake_up(&dlm->migration_wq);
3460 }
3461 
3462 void dlm_force_free_mles(struct dlm_ctxt *dlm)
3463 {
3464         int i;
3465         struct hlist_head *bucket;
3466         struct dlm_master_list_entry *mle;
3467         struct hlist_node *tmp;
3468 
3469         /*
3470          * We notified all other nodes that we are exiting the domain and
3471          * marked the dlm state to DLM_CTXT_LEAVING. If any mles are still
3472          * around we force free them and wake any processes that are waiting
3473          * on the mles
3474          */
3475         spin_lock(&dlm->spinlock);
3476         spin_lock(&dlm->master_lock);
3477 
3478         BUG_ON(dlm->dlm_state != DLM_CTXT_LEAVING);
3479         BUG_ON((find_next_bit(dlm->domain_map, O2NM_MAX_NODES, 0) < O2NM_MAX_NODES));
3480 
3481         for (i = 0; i < DLM_HASH_BUCKETS; i++) {
3482                 bucket = dlm_master_hash(dlm, i);
3483                 hlist_for_each_entry_safe(mle, tmp, bucket, master_hash_node) {
3484                         if (mle->type != DLM_MLE_BLOCK) {
3485                                 mlog(ML_ERROR, "bad mle: %p\n", mle);
3486                                 dlm_print_one_mle(mle);
3487                         }
3488                         atomic_set(&mle->woken, 1);
3489                         wake_up(&mle->wq);
3490 
3491                         __dlm_unlink_mle(dlm, mle);
3492                         __dlm_mle_detach_hb_events(dlm, mle);
3493                         __dlm_put_mle(mle);
3494                 }
3495         }
3496         spin_unlock(&dlm->master_lock);
3497         spin_unlock(&dlm->spinlock);
3498 }
3499 

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