fs/ocfs2/dlm/dlmmaster.c

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