fs/ocfs2/dlm/dlmmaster.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * dlmmod.c
   5  *
   6  * standalone DLM module
   7  *
   8  * Copyright (C) 2004 Oracle.  All rights reserved.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2 of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public
  21  * License along with this program; if not, write to the
  22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23  * Boston, MA 021110-1307, USA.
  24  *
  25  */
  26
  27
  28 #include <linux/module.h>
  29 #include <linux/fs.h>
  30 #include <linux/types.h>
  31 #include <linux/slab.h>
  32 #include <linux/highmem.h>
  33 #include <linux/utsname.h>
  34 #include <linux/init.h>
  35 #include <linux/sysctl.h>
  36 #include <linux/random.h>
  37 #include <linux/blkdev.h>
  38 #include <linux/socket.h>
  39 #include <linux/inet.h>
  40 #include <linux/spinlock.h>
  41 #include <linux/delay.h>
  42
  43
  44 #include "cluster/heartbeat.h"
  45 #include "cluster/nodemanager.h"
  46 #include "cluster/tcp.h"
  47
  48 #include "dlmapi.h"
  49 #include "dlmcommon.h"
  50 #include "dlmdebug.h"
  51 #include "dlmdomain.h"
  52
  53 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
  54 #include "cluster/masklog.h"
  55
  56 enum dlm_mle_type {
  57         DLM_MLE_BLOCK,
  58         DLM_MLE_MASTER,
  59         DLM_MLE_MIGRATION
  60 };
  61
  62 struct dlm_lock_name
  63 {
  64         u8 len;
  65         u8 name[DLM_LOCKID_NAME_MAX];
  66 };
  67
  68 struct dlm_master_list_entry
  69 {
  70         struct list_head list;
  71         struct list_head hb_events;
  72         struct dlm_ctxt *dlm;
  73         spinlock_t spinlock;
  74         wait_queue_head_t wq;
  75         atomic_t woken;
  76         struct kref mle_refs;
  77         int inuse;
  78         unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
  79         unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
  80         unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
  81         unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
  82         u8 master;
  83         u8 new_master;
  84         enum dlm_mle_type type;
  85         struct o2hb_callback_func mle_hb_up;
  86         struct o2hb_callback_func mle_hb_down;
  87         union {
  88                 struct dlm_lock_resource *res;
  89                 struct dlm_lock_name name;
  90         } u;
  91 };
  92
  93 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
  94                               struct dlm_master_list_entry *mle,
  95                               struct o2nm_node *node,
  96                               int idx);
  97 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
  98                             struct dlm_master_list_entry *mle,
  99                             struct o2nm_node *node,
 100                             int idx);
 101
 102 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data);
 103 static int dlm_do_assert_master(struct dlm_ctxt *dlm, const char *lockname,
 104                                 unsigned int namelen, void *nodemap,
 105                                 u32 flags);
 106
 107 static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
 108                                 struct dlm_master_list_entry *mle,
 109                                 const char *name,
 110                                 unsigned int namelen)
 111 {
 112         struct dlm_lock_resource *res;
 113
 114         if (dlm != mle->dlm)
 115                 return 0;
 116
 117         if (mle->type == DLM_MLE_BLOCK ||
 118             mle->type == DLM_MLE_MIGRATION) {
 119                 if (namelen != mle->u.name.len ||
 120                     memcmp(name, mle->u.name.name, namelen)!=0)
 121                         return 0;
 122         } else {
 123                 res = mle->u.res;
 124                 if (namelen != res->lockname.len ||
 125                     memcmp(res->lockname.name, name, namelen) != 0)
 126                         return 0;
 127         }
 128         return 1;
 129 }
 130
 131 #if 0
 132 /* Code here is included but defined out as it aids debugging */
 133
 134 #define dlm_print_nodemap(m)  _dlm_print_nodemap(m,#m)
 135 void _dlm_print_nodemap(unsigned long *map, const char *mapname)
 136 {
 137         int i;
 138         printk("%s=[ ", mapname);
 139         for (i=0; i<O2NM_MAX_NODES; i++)
 140                 if (test_bit(i, map))
 141                         printk("%d ", i);
 142         printk("]");
 143 }
 144
 145 void dlm_print_one_mle(struct dlm_master_list_entry *mle)
 146 {
 147         int refs;
 148         char *type;
 149         char attached;
 150         u8 master;
 151         unsigned int namelen;
 152         const char *name;
 153         struct kref *k;
 154         unsigned long *maybe = mle->maybe_map,
 155                       *vote = mle->vote_map,
 156                       *resp = mle->response_map,
 157                       *node = mle->node_map;
 158
 159         k = &mle->mle_refs;
 160         if (mle->type == DLM_MLE_BLOCK)
 161                 type = "BLK";
 162         else if (mle->type == DLM_MLE_MASTER)
 163                 type = "MAS";
 164         else
 165                 type = "MIG";
 166         refs = atomic_read(&k->refcount);
 167         master = mle->master;
 168         attached = (list_empty(&mle->hb_events) ? 'N' : 'Y');
 169
 170         if (mle->type != DLM_MLE_MASTER) {
 171                 namelen = mle->u.name.len;
 172                 name = mle->u.name.name;
 173         } else {
 174                 namelen = mle->u.res->lockname.len;
 175                 name = mle->u.res->lockname.name;
 176         }
 177
 178         mlog(ML_NOTICE, "%.*s: %3s refs=%3d mas=%3u new=%3u evt=%c inuse=%d ",
 179                   namelen, name, type, refs, master, mle->new_master, attached,
 180                   mle->inuse);
 181         dlm_print_nodemap(maybe);
 182         printk(", ");
 183         dlm_print_nodemap(vote);
 184         printk(", ");
 185         dlm_print_nodemap(resp);
 186         printk(", ");
 187         dlm_print_nodemap(node);
 188         printk(", ");
 189         printk("\n");
 190 }
 191
 192 static void dlm_dump_mles(struct dlm_ctxt *dlm)
 193 {
 194         struct dlm_master_list_entry *mle;
 195         struct list_head *iter;
 196
 197         mlog(ML_NOTICE, "dumping all mles for domain %s:\n", dlm->name);
 198         spin_lock(&dlm->master_lock);
 199         list_for_each(iter, &dlm->master_list) {
 200                 mle = list_entry(iter, struct dlm_master_list_entry, list);
 201                 dlm_print_one_mle(mle);
 202         }
 203         spin_unlock(&dlm->master_lock);
 204 }
 205
 206 int dlm_dump_all_mles(const char __user *data, unsigned int len)
 207 {
 208         struct list_head *iter;
 209         struct dlm_ctxt *dlm;
 210
 211         spin_lock(&dlm_domain_lock);
 212         list_for_each(iter, &dlm_domains) {
 213                 dlm = list_entry (iter, struct dlm_ctxt, list);
 214                 mlog(ML_NOTICE, "found dlm: %p, name=%s\n", dlm, dlm->name);
 215                 dlm_dump_mles(dlm);
 216         }
 217         spin_unlock(&dlm_domain_lock);
 218         return len;
 219 }
 220 EXPORT_SYMBOL_GPL(dlm_dump_all_mles);
 221
 222 #endif  /*  0  */
 223
 224
 225 static kmem_cache_t *dlm_mle_cache = NULL;
 226
 227
 228 static void dlm_mle_release(struct kref *kref);
 229 static void dlm_init_mle(struct dlm_master_list_entry *mle,
 230                         enum dlm_mle_type type,
 231                         struct dlm_ctxt *dlm,
 232                         struct dlm_lock_resource *res,
 233                         const char *name,
 234                         unsigned int namelen);
 235 static void dlm_put_mle(struct dlm_master_list_entry *mle);
 236 static void __dlm_put_mle(struct dlm_master_list_entry *mle);
 237 static int dlm_find_mle(struct dlm_ctxt *dlm,
 238                         struct dlm_master_list_entry **mle,
 239                         char *name, unsigned int namelen);
 240
 241 static int dlm_do_master_request(struct dlm_master_list_entry *mle, int to);
 242
 243
 244 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
 245                                      struct dlm_lock_resource *res,
 246                                      struct dlm_master_list_entry *mle,
 247                                      int *blocked);
 248 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
 249                                     struct dlm_lock_resource *res,
 250                                     struct dlm_master_list_entry *mle,
 251                                     int blocked);
 252 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
 253                                  struct dlm_lock_resource *res,
 254                                  struct dlm_master_list_entry *mle,
 255                                  struct dlm_master_list_entry **oldmle,
 256                                  const char *name, unsigned int namelen,
 257                                  u8 new_master, u8 master);
 258
 259 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
 260                                     struct dlm_lock_resource *res);
 261 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
 262                                       struct dlm_lock_resource *res);
 263 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
 264                                        struct dlm_lock_resource *res,
 265                                        u8 target);
 266 static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
 267                                        struct dlm_lock_resource *res);
 268
 269
 270 int dlm_is_host_down(int errno)
 271 {
 272         switch (errno) {
 273                 case -EBADF:
 274                 case -ECONNREFUSED:
 275                 case -ENOTCONN:
 276                 case -ECONNRESET:
 277                 case -EPIPE:
 278                 case -EHOSTDOWN:
 279                 case -EHOSTUNREACH:
 280                 case -ETIMEDOUT:
 281                 case -ECONNABORTED:
 282                 case -ENETDOWN:
 283                 case -ENETUNREACH:
 284                 case -ENETRESET:
 285                 case -ESHUTDOWN:
 286                 case -ENOPROTOOPT:
 287                 case -EINVAL:   /* if returned from our tcp code,
 288                                    this means there is no socket */
 289                         return 1;
 290         }
 291         return 0;
 292 }
 293
 294
 295 /*
 296  * MASTER LIST FUNCTIONS
 297  */
 298
 299
 300 /*
 301  * regarding master list entries and heartbeat callbacks:
 302  *
 303  * in order to avoid sleeping and allocation that occurs in
 304  * heartbeat, master list entries are simply attached to the
 305  * dlm's established heartbeat callbacks.  the mle is attached
 306  * when it is created, and since the dlm->spinlock is held at
 307  * that time, any heartbeat event will be properly discovered
 308  * by the mle.  the mle needs to be detached from the
 309  * dlm->mle_hb_events list as soon as heartbeat events are no
 310  * longer useful to the mle, and before the mle is freed.
 311  *
 312  * as a general rule, heartbeat events are no longer needed by
 313  * the mle once an "answer" regarding the lock master has been
 314  * received.
 315  */
 316 static inline void __dlm_mle_attach_hb_events(struct dlm_ctxt *dlm,
 317                                               struct dlm_master_list_entry *mle)
 318 {
 319         assert_spin_locked(&dlm->spinlock);
 320
 321         list_add_tail(&mle->hb_events, &dlm->mle_hb_events);
 322 }
 323
 324
 325 static inline void __dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
 326                                               struct dlm_master_list_entry *mle)
 327 {
 328         if (!list_empty(&mle->hb_events))
 329                 list_del_init(&mle->hb_events);
 330 }
 331
 332
 333 static inline void dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
 334                                             struct dlm_master_list_entry *mle)
 335 {
 336         spin_lock(&dlm->spinlock);
 337         __dlm_mle_detach_hb_events(dlm, mle);
 338         spin_unlock(&dlm->spinlock);
 339 }
 340
 341 static void dlm_get_mle_inuse(struct dlm_master_list_entry *mle)
 342 {
 343         struct dlm_ctxt *dlm;
 344         dlm = mle->dlm;
 345
 346         assert_spin_locked(&dlm->spinlock);
 347         assert_spin_locked(&dlm->master_lock);
 348         mle->inuse++;
 349         kref_get(&mle->mle_refs);
 350 }
 351
 352 static void dlm_put_mle_inuse(struct dlm_master_list_entry *mle)
 353 {
 354         struct dlm_ctxt *dlm;
 355         dlm = mle->dlm;
 356
 357         spin_lock(&dlm->spinlock);
 358         spin_lock(&dlm->master_lock);
 359         mle->inuse--;
 360         __dlm_put_mle(mle);
 361         spin_unlock(&dlm->master_lock);
 362         spin_unlock(&dlm->spinlock);
 363
 364 }
 365
 366 /* remove from list and free */
 367 static void __dlm_put_mle(struct dlm_master_list_entry *mle)
 368 {
 369         struct dlm_ctxt *dlm;
 370         dlm = mle->dlm;
 371
 372         assert_spin_locked(&dlm->spinlock);
 373         assert_spin_locked(&dlm->master_lock);
 374         if (!atomic_read(&mle->mle_refs.refcount)) {
 375                 /* this may or may not crash, but who cares.
 376                  * it's a BUG. */
 377                 mlog(ML_ERROR, "bad mle: %p\n", mle);
 378                 dlm_print_one_mle(mle);
 379                 BUG();
 380         } else
 381                 kref_put(&mle->mle_refs, dlm_mle_release);
 382 }
 383
 384
 385 /* must not have any spinlocks coming in */
 386 static void dlm_put_mle(struct dlm_master_list_entry *mle)
 387 {
 388         struct dlm_ctxt *dlm;
 389         dlm = mle->dlm;
 390
 391         spin_lock(&dlm->spinlock);
 392         spin_lock(&dlm->master_lock);
 393         __dlm_put_mle(mle);
 394         spin_unlock(&dlm->master_lock);
 395         spin_unlock(&dlm->spinlock);
 396 }
 397
 398 static inline void dlm_get_mle(struct dlm_master_list_entry *mle)
 399 {
 400         kref_get(&mle->mle_refs);
 401 }
 402
 403 static void dlm_init_mle(struct dlm_master_list_entry *mle,
 404                         enum dlm_mle_type type,
 405                         struct dlm_ctxt *dlm,
 406                         struct dlm_lock_resource *res,
 407                         const char *name,
 408                         unsigned int namelen)
 409 {
 410         assert_spin_locked(&dlm->spinlock);
 411
 412         mle->dlm = dlm;
 413         mle->type = type;
 414         INIT_LIST_HEAD(&mle->list);
 415         INIT_LIST_HEAD(&mle->hb_events);
 416         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
 417         spin_lock_init(&mle->spinlock);
 418         init_waitqueue_head(&mle->wq);
 419         atomic_set(&mle->woken, 0);
 420         kref_init(&mle->mle_refs);
 421         memset(mle->response_map, 0, sizeof(mle->response_map));
 422         mle->master = O2NM_MAX_NODES;
 423         mle->new_master = O2NM_MAX_NODES;
 424         mle->inuse = 0;
 425
 426         if (mle->type == DLM_MLE_MASTER) {
 427                 BUG_ON(!res);
 428                 mle->u.res = res;
 429         } else if (mle->type == DLM_MLE_BLOCK) {
 430                 BUG_ON(!name);
 431                 memcpy(mle->u.name.name, name, namelen);
 432                 mle->u.name.len = namelen;
 433         } else /* DLM_MLE_MIGRATION */ {
 434                 BUG_ON(!name);
 435                 memcpy(mle->u.name.name, name, namelen);
 436                 mle->u.name.len = namelen;
 437         }
 438
 439         /* copy off the node_map and register hb callbacks on our copy */
 440         memcpy(mle->node_map, dlm->domain_map, sizeof(mle->node_map));
 441         memcpy(mle->vote_map, dlm->domain_map, sizeof(mle->vote_map));
 442         clear_bit(dlm->node_num, mle->vote_map);
 443         clear_bit(dlm->node_num, mle->node_map);
 444
 445         /* attach the mle to the domain node up/down events */
 446         __dlm_mle_attach_hb_events(dlm, mle);
 447 }
 448
 449
 450 /* returns 1 if found, 0 if not */
 451 static int dlm_find_mle(struct dlm_ctxt *dlm,
 452                         struct dlm_master_list_entry **mle,
 453                         char *name, unsigned int namelen)
 454 {
 455         struct dlm_master_list_entry *tmpmle;
 456         struct list_head *iter;
 457
 458         assert_spin_locked(&dlm->master_lock);
 459
 460         list_for_each(iter, &dlm->master_list) {
 461                 tmpmle = list_entry(iter, struct dlm_master_list_entry, list);
 462                 if (!dlm_mle_equal(dlm, tmpmle, name, namelen))
 463                         continue;
 464                 dlm_get_mle(tmpmle);
 465                 *mle = tmpmle;
 466                 return 1;
 467         }
 468         return 0;
 469 }
 470
 471 void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up)
 472 {
 473         struct dlm_master_list_entry *mle;
 474         struct list_head *iter;
 475
 476         assert_spin_locked(&dlm->spinlock);
 477
 478         list_for_each(iter, &dlm->mle_hb_events) {
 479                 mle = list_entry(iter, struct dlm_master_list_entry,
 480                                  hb_events);
 481                 if (node_up)
 482                         dlm_mle_node_up(dlm, mle, NULL, idx);
 483                 else
 484                         dlm_mle_node_down(dlm, mle, NULL, idx);
 485         }
 486 }
 487
 488 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
 489                               struct dlm_master_list_entry *mle,
 490                               struct o2nm_node *node, int idx)
 491 {
 492         spin_lock(&mle->spinlock);
 493
 494         if (!test_bit(idx, mle->node_map))
 495                 mlog(0, "node %u already removed from nodemap!\n", idx);
 496         else
 497                 clear_bit(idx, mle->node_map);
 498
 499         spin_unlock(&mle->spinlock);
 500 }
 501
 502 static void dlm_mle_node_up(struct dlm_ctxt *dlm,
 503                             struct dlm_master_list_entry *mle,
 504                             struct o2nm_node *node, int idx)
 505 {
 506         spin_lock(&mle->spinlock);
 507
 508         if (test_bit(idx, mle->node_map))
 509                 mlog(0, "node %u already in node map!\n", idx);
 510         else
 511                 set_bit(idx, mle->node_map);
 512
 513         spin_unlock(&mle->spinlock);
 514 }
 515
 516
 517 int dlm_init_mle_cache(void)
 518 {
 519         dlm_mle_cache = kmem_cache_create("dlm_mle_cache",
 520                                           sizeof(struct dlm_master_list_entry),
 521                                           0, SLAB_HWCACHE_ALIGN,
 522                                           NULL, NULL);
 523         if (dlm_mle_cache == NULL)
 524                 return -ENOMEM;
 525         return 0;
 526 }
 527
 528 void dlm_destroy_mle_cache(void)
 529 {
 530         if (dlm_mle_cache)
 531                 kmem_cache_destroy(dlm_mle_cache);
 532 }
 533
 534 static void dlm_mle_release(struct kref *kref)
 535 {
 536         struct dlm_master_list_entry *mle;
 537         struct dlm_ctxt *dlm;
 538
 539         mlog_entry_void();
 540
 541         mle = container_of(kref, struct dlm_master_list_entry, mle_refs);
 542         dlm = mle->dlm;
 543
 544         if (mle->type != DLM_MLE_MASTER) {
 545                 mlog(0, "calling mle_release for %.*s, type %d\n",
 546                      mle->u.name.len, mle->u.name.name, mle->type);
 547         } else {
 548                 mlog(0, "calling mle_release for %.*s, type %d\n",
 549                      mle->u.res->lockname.len,
 550                      mle->u.res->lockname.name, mle->type);
 551         }
 552         assert_spin_locked(&dlm->spinlock);
 553         assert_spin_locked(&dlm->master_lock);
 554
 555         /* remove from list if not already */
 556         if (!list_empty(&mle->list))
 557                 list_del_init(&mle->list);
 558
 559         /* detach the mle from the domain node up/down events */
 560         __dlm_mle_detach_hb_events(dlm, mle);
 561
 562         /* NOTE: kfree under spinlock here.
 563          * if this is bad, we can move this to a freelist. */
 564         kmem_cache_free(dlm_mle_cache, mle);
 565 }
 566
 567
 568 /*
 569  * LOCK RESOURCE FUNCTIONS
 570  */
 571
 572 static void dlm_set_lockres_owner(struct dlm_ctxt *dlm,
 573                                   struct dlm_lock_resource *res,
 574                                   u8 owner)
 575 {
 576         assert_spin_locked(&res->spinlock);
 577
 578         mlog_entry("%.*s, %u\n", res->lockname.len, res->lockname.name, owner);
 579
 580         if (owner == dlm->node_num)
 581                 atomic_inc(&dlm->local_resources);
 582         else if (owner == DLM_LOCK_RES_OWNER_UNKNOWN)
 583                 atomic_inc(&dlm->unknown_resources);
 584         else
 585                 atomic_inc(&dlm->remote_resources);
 586
 587         res->owner = owner;
 588 }
 589
 590 void dlm_change_lockres_owner(struct dlm_ctxt *dlm,
 591                               struct dlm_lock_resource *res, u8 owner)
 592 {
 593         assert_spin_locked(&res->spinlock);
 594
 595         if (owner == res->owner)
 596                 return;
 597
 598         if (res->owner == dlm->node_num)
 599                 atomic_dec(&dlm->local_resources);
 600         else if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN)
 601                 atomic_dec(&dlm->unknown_resources);
 602         else
 603                 atomic_dec(&dlm->remote_resources);
 604
 605         dlm_set_lockres_owner(dlm, res, owner);
 606 }
 607
 608
 609 static void dlm_lockres_release(struct kref *kref)
 610 {
 611         struct dlm_lock_resource *res;
 612
 613         res = container_of(kref, struct dlm_lock_resource, refs);
 614
 615         /* This should not happen -- all lockres' have a name
 616          * associated with them at init time. */
 617         BUG_ON(!res->lockname.name);
 618
 619         mlog(0, "destroying lockres %.*s\n", res->lockname.len,
 620              res->lockname.name);
 621
 622         if (!hlist_unhashed(&res->hash_node) ||
 623             !list_empty(&res->granted) ||
 624             !list_empty(&res->converting) ||
 625             !list_empty(&res->blocked) ||
 626             !list_empty(&res->dirty) ||
 627             !list_empty(&res->recovering) ||
 628             !list_empty(&res->purge)) {
 629                 mlog(ML_ERROR,
 630                      "Going to BUG for resource %.*s."
 631                      "  We're on a list! [%c%c%c%c%c%c%c]\n",
 632                      res->lockname.len, res->lockname.name,
 633                      !hlist_unhashed(&res->hash_node) ? 'H' : ' ',
 634                      !list_empty(&res->granted) ? 'G' : ' ',
 635                      !list_empty(&res->converting) ? 'C' : ' ',
 636                      !list_empty(&res->blocked) ? 'B' : ' ',
 637                      !list_empty(&res->dirty) ? 'D' : ' ',
 638                      !list_empty(&res->recovering) ? 'R' : ' ',
 639                      !list_empty(&res->purge) ? 'P' : ' ');
 640
 641                 dlm_print_one_lock_resource(res);
 642         }
 643
 644         /* By the time we're ready to blow this guy away, we shouldn't
 645          * be on any lists. */
 646         BUG_ON(!hlist_unhashed(&res->hash_node));
 647         BUG_ON(!list_empty(&res->granted));
 648         BUG_ON(!list_empty(&res->converting));
 649         BUG_ON(!list_empty(&res->blocked));
 650         BUG_ON(!list_empty(&res->dirty));
 651         BUG_ON(!list_empty(&res->recovering));
 652         BUG_ON(!list_empty(&res->purge));
 653
 654         kfree(res->lockname.name);
 655
 656         kfree(res);
 657 }
 658
 659 void dlm_lockres_put(struct dlm_lock_resource *res)
 660 {
 661         kref_put(&res->refs, dlm_lockres_release);
 662 }
 663
 664 static void dlm_init_lockres(struct dlm_ctxt *dlm,
 665                              struct dlm_lock_resource *res,
 666                              const char *name, unsigned int namelen)
 667 {
 668         char *qname;
 669
 670         /* If we memset here, we lose our reference to the kmalloc'd
 671          * res->lockname.name, so be sure to init every field
 672          * correctly! */
 673
 674         qname = (char *) res->lockname.name;
 675         memcpy(qname, name, namelen);
 676
 677         res->lockname.len = namelen;
 678         res->lockname.hash = dlm_lockid_hash(name, namelen);
 679
 680         init_waitqueue_head(&res->wq);
 681         spin_lock_init(&res->spinlock);
 682         INIT_HLIST_NODE(&res->hash_node);
 683         INIT_LIST_HEAD(&res->granted);
 684         INIT_LIST_HEAD(&res->converting);
 685         INIT_LIST_HEAD(&res->blocked);
 686         INIT_LIST_HEAD(&res->dirty);
 687         INIT_LIST_HEAD(&res->recovering);
 688         INIT_LIST_HEAD(&res->purge);
 689         atomic_set(&res->asts_reserved, 0);
 690         res->migration_pending = 0;
 691
 692         kref_init(&res->refs);
 693
 694         /* just for consistency */
 695         spin_lock(&res->spinlock);
 696         dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
 697         spin_unlock(&res->spinlock);
 698
 699         res->state = DLM_LOCK_RES_IN_PROGRESS;
 700
 701         res->last_used = 0;
 702
 703         memset(res->lvb, 0, DLM_LVB_LEN);
 704 }
 705
 706 struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
 707                                    const char *name,
 708                                    unsigned int namelen)
 709 {
 710         struct dlm_lock_resource *res;
 711
 712         res = kmalloc(sizeof(struct dlm_lock_resource), GFP_KERNEL);
 713         if (!res)
 714                 return NULL;
 715
 716         res->lockname.name = kmalloc(namelen, GFP_KERNEL);
 717         if (!res->lockname.name) {
 718                 kfree(res);
 719                 return NULL;
 720         }
 721
 722         dlm_init_lockres(dlm, res, name, namelen);
 723         return res;
 724 }
 725
 726 /*
 727  * lookup a lock resource by name.
 728  * may already exist in the hashtable.
 729  * lockid is null terminated
 730  *
 731  * if not, allocate enough for the lockres and for
 732  * the temporary structure used in doing the mastering.
 733  *
 734  * also, do a lookup in the dlm->master_list to see
 735  * if another node has begun mastering the same lock.
 736  * if so, there should be a block entry in there
 737  * for this name, and we should *not* attempt to master
 738  * the lock here.   need to wait around for that node
 739  * to assert_master (or die).
 740  *
 741  */
 742 struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm,
 743                                           const char *lockid,
 744                                           int flags)
 745 {
 746         struct dlm_lock_resource *tmpres=NULL, *res=NULL;
 747         struct dlm_master_list_entry *mle = NULL;
 748         struct dlm_master_list_entry *alloc_mle = NULL;
 749         int blocked = 0;
 750         int ret, nodenum;
 751         struct dlm_node_iter iter;
 752         unsigned int namelen, hash;
 753         int tries = 0;
 754         int bit, wait_on_recovery = 0;
 755
 756         BUG_ON(!lockid);
 757
 758         namelen = strlen(lockid);
 759         hash = dlm_lockid_hash(lockid, namelen);
 760
 761         mlog(0, "get lockres %s (len %d)\n", lockid, namelen);
 762
 763 lookup:
 764         spin_lock(&dlm->spinlock);
 765         tmpres = __dlm_lookup_lockres(dlm, lockid, namelen, hash);
 766         if (tmpres) {
 767                 spin_unlock(&dlm->spinlock);
 768                 mlog(0, "found in hash!\n");
 769                 if (res)
 770                         dlm_lockres_put(res);
 771                 res = tmpres;
 772                 goto leave;
 773         }
 774
 775         if (!res) {
 776                 spin_unlock(&dlm->spinlock);
 777                 mlog(0, "allocating a new resource\n");
 778                 /* nothing found and we need to allocate one. */
 779                 alloc_mle = (struct dlm_master_list_entry *)
 780                         kmem_cache_alloc(dlm_mle_cache, GFP_KERNEL);
 781                 if (!alloc_mle)
 782                         goto leave;
 783                 res = dlm_new_lockres(dlm, lockid, namelen);
 784                 if (!res)
 785                         goto leave;
 786                 goto lookup;
 787         }
 788
 789         mlog(0, "no lockres found, allocated our own: %p\n", res);
 790
 791         if (flags & LKM_LOCAL) {
 792                 /* caller knows it's safe to assume it's not mastered elsewhere
 793                  * DONE!  return right away */
 794                 spin_lock(&res->spinlock);
 795                 dlm_change_lockres_owner(dlm, res, dlm->node_num);
 796                 __dlm_insert_lockres(dlm, res);
 797                 spin_unlock(&res->spinlock);
 798                 spin_unlock(&dlm->spinlock);
 799                 /* lockres still marked IN_PROGRESS */
 800                 goto wake_waiters;
 801         }
 802
 803         /* check master list to see if another node has started mastering it */
 804         spin_lock(&dlm->master_lock);
 805
 806         /* if we found a block, wait for lock to be mastered by another node */
 807         blocked = dlm_find_mle(dlm, &mle, (char *)lockid, namelen);
 808         if (blocked) {
 809                 if (mle->type == DLM_MLE_MASTER) {
 810                         mlog(ML_ERROR, "master entry for nonexistent lock!\n");
 811                         BUG();
 812                 } else if (mle->type == DLM_MLE_MIGRATION) {
 813                         /* migration is in progress! */
 814                         /* the good news is that we now know the
 815                          * "current" master (mle->master). */
 816
 817                         spin_unlock(&dlm->master_lock);
 818                         assert_spin_locked(&dlm->spinlock);
 819
 820                         /* set the lockres owner and hash it */
 821                         spin_lock(&res->spinlock);
 822                         dlm_set_lockres_owner(dlm, res, mle->master);
 823                         __dlm_insert_lockres(dlm, res);
 824                         spin_unlock(&res->spinlock);
 825                         spin_unlock(&dlm->spinlock);
 826
 827                         /* master is known, detach */
 828                         dlm_mle_detach_hb_events(dlm, mle);
 829                         dlm_put_mle(mle);
 830                         mle = NULL;
 831                         goto wake_waiters;
 832                 }
 833         } else {
 834                 /* go ahead and try to master lock on this node */
 835                 mle = alloc_mle;
 836                 /* make sure this does not get freed below */
 837                 alloc_mle = NULL;
 838                 dlm_init_mle(mle, DLM_MLE_MASTER, dlm, res, NULL, 0);
 839                 set_bit(dlm->node_num, mle->maybe_map);
 840                 list_add(&mle->list, &dlm->master_list);
 841
 842                 /* still holding the dlm spinlock, check the recovery map
 843                  * to see if there are any nodes that still need to be
 844                  * considered.  these will not appear in the mle nodemap
 845                  * but they might own this lockres.  wait on them. */
 846                 bit = find_next_bit(dlm->recovery_map, O2NM_MAX_NODES, 0);
 847                 if (bit < O2NM_MAX_NODES) {
 848                         mlog(ML_NOTICE, "%s:%.*s: at least one node (%d) to"
 849                              "recover before lock mastery can begin\n",
 850                              dlm->name, namelen, (char *)lockid, bit);
 851                         wait_on_recovery = 1;
 852                 }
 853         }
 854
 855         /* at this point there is either a DLM_MLE_BLOCK or a
 856          * DLM_MLE_MASTER on the master list, so it's safe to add the
 857          * lockres to the hashtable.  anyone who finds the lock will
 858          * still have to wait on the IN_PROGRESS. */
 859
 860         /* finally add the lockres to its hash bucket */
 861         __dlm_insert_lockres(dlm, res);
 862         /* get an extra ref on the mle in case this is a BLOCK
 863          * if so, the creator of the BLOCK may try to put the last
 864          * ref at this time in the assert master handler, so we
 865          * need an extra one to keep from a bad ptr deref. */
 866         dlm_get_mle_inuse(mle);
 867         spin_unlock(&dlm->master_lock);
 868         spin_unlock(&dlm->spinlock);
 869
 870 redo_request:
 871         while (wait_on_recovery) {
 872                 /* any cluster changes that occurred after dropping the
 873                  * dlm spinlock would be detectable be a change on the mle,
 874                  * so we only need to clear out the recovery map once. */
 875                 if (dlm_is_recovery_lock(lockid, namelen)) {
 876                         mlog(ML_NOTICE, "%s: recovery map is not empty, but "
 877                              "must master $RECOVERY lock now\n", dlm->name);
 878                         if (!dlm_pre_master_reco_lockres(dlm, res))
 879                                 wait_on_recovery = 0;
 880                         else {
 881                                 mlog(0, "%s: waiting 500ms for heartbeat state "
 882                                     "change\n", dlm->name);
 883                                 msleep(500);
 884                         }
 885                         continue;
 886                 }
 887
 888                 dlm_kick_recovery_thread(dlm);
 889                 msleep(1000);
 890                 dlm_wait_for_recovery(dlm);
 891
 892                 spin_lock(&dlm->spinlock);
 893                 bit = find_next_bit(dlm->recovery_map, O2NM_MAX_NODES, 0);
 894                 if (bit < O2NM_MAX_NODES) {
 895                         mlog(ML_NOTICE, "%s:%.*s: at least one node (%d) to"
 896                              "recover before lock mastery can begin\n",
 897                              dlm->name, namelen, (char *)lockid, bit);
 898                         wait_on_recovery = 1;
 899                 } else
 900                         wait_on_recovery = 0;
 901                 spin_unlock(&dlm->spinlock);
 902         }
 903
 904         /* must wait for lock to be mastered elsewhere */
 905         if (blocked)
 906                 goto wait;
 907
 908         ret = -EINVAL;
 909         dlm_node_iter_init(mle->vote_map, &iter);
 910         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
 911                 ret = dlm_do_master_request(mle, nodenum);
 912                 if (ret < 0)
 913                         mlog_errno(ret);
 914                 if (mle->master != O2NM_MAX_NODES) {
 915                         /* found a master ! */
 916                         if (mle->master <= nodenum)
 917                                 break;
 918                         /* if our master request has not reached the master
 919                          * yet, keep going until it does.  this is how the
 920                          * master will know that asserts are needed back to
 921                          * the lower nodes. */
 922                         mlog(0, "%s:%.*s: requests only up to %u but master "
 923                              "is %u, keep going\n", dlm->name, namelen,
 924                              lockid, nodenum, mle->master);
 925                 }
 926         }
 927
 928 wait:
 929         /* keep going until the response map includes all nodes */
 930         ret = dlm_wait_for_lock_mastery(dlm, res, mle, &blocked);
 931         if (ret < 0) {
 932                 wait_on_recovery = 1;
 933                 mlog(0, "%s:%.*s: node map changed, redo the "
 934                      "master request now, blocked=%d\n",
 935                      dlm->name, res->lockname.len,
 936                      res->lockname.name, blocked);
 937                 if (++tries > 20) {
 938                         mlog(ML_ERROR, "%s:%.*s: spinning on "
 939                              "dlm_wait_for_lock_mastery, blocked=%d\n",
 940                              dlm->name, res->lockname.len,
 941                              res->lockname.name, blocked);
 942                         dlm_print_one_lock_resource(res);
 943                         /* dlm_print_one_mle(mle); */
 944                         tries = 0;
 945                 }
 946                 goto redo_request;
 947         }
 948
 949         mlog(0, "lockres mastered by %u\n", res->owner);
 950         /* make sure we never continue without this */
 951         BUG_ON(res->owner == O2NM_MAX_NODES);
 952
 953         /* master is known, detach if not already detached */
 954         dlm_mle_detach_hb_events(dlm, mle);
 955         dlm_put_mle(mle);
 956         /* put the extra ref */
 957         dlm_put_mle_inuse(mle);
 958
 959 wake_waiters:
 960         spin_lock(&res->spinlock);
 961         res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
 962         spin_unlock(&res->spinlock);
 963         wake_up(&res->wq);
 964
 965 leave:
 966         /* need to free the unused mle */
 967         if (alloc_mle)
 968                 kmem_cache_free(dlm_mle_cache, alloc_mle);
 969
 970         return res;
 971 }
 972
 973
 974 #define DLM_MASTERY_TIMEOUT_MS   5000
 975
 976 static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
 977                                      struct dlm_lock_resource *res,
 978                                      struct dlm_master_list_entry *mle,
 979                                      int *blocked)
 980 {
 981         u8 m;
 982         int ret, bit;
 983         int map_changed, voting_done;
 984         int assert, sleep;
 985
 986 recheck:
 987         ret = 0;
 988         assert = 0;
 989
 990         /* check if another node has already become the owner */
 991         spin_lock(&res->spinlock);
 992         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
 993                 mlog(0, "%s:%.*s: owner is suddenly %u\n", dlm->name,
 994                      res->lockname.len, res->lockname.name, res->owner);
 995                 spin_unlock(&res->spinlock);
 996                 /* this will cause the master to re-assert across
 997                  * the whole cluster, freeing up mles */
 998                 if (res->owner != dlm->node_num) {
 999                         ret = dlm_do_master_request(mle, res->owner);
1000                         if (ret < 0) {
1001                                 /* give recovery a chance to run */
1002                                 mlog(ML_ERROR, "link to %u went down?: %d\n", res->owner, ret);
1003                                 msleep(500);
1004                                 goto recheck;
1005                         }
1006                 }
1007                 ret = 0;
1008                 goto leave;
1009         }
1010         spin_unlock(&res->spinlock);
1011
1012         spin_lock(&mle->spinlock);
1013         m = mle->master;
1014         map_changed = (memcmp(mle->vote_map, mle->node_map,
1015                               sizeof(mle->vote_map)) != 0);
1016         voting_done = (memcmp(mle->vote_map, mle->response_map,
1017                              sizeof(mle->vote_map)) == 0);
1018
1019         /* restart if we hit any errors */
1020         if (map_changed) {
1021                 int b;
1022                 mlog(0, "%s: %.*s: node map changed, restarting\n",
1023                      dlm->name, res->lockname.len, res->lockname.name);
1024                 ret = dlm_restart_lock_mastery(dlm, res, mle, *blocked);
1025                 b = (mle->type == DLM_MLE_BLOCK);
1026                 if ((*blocked && !b) || (!*blocked && b)) {
1027                         mlog(0, "%s:%.*s: status change: old=%d new=%d\n",
1028                              dlm->name, res->lockname.len, res->lockname.name,
1029                              *blocked, b);
1030                         *blocked = b;
1031                 }
1032                 spin_unlock(&mle->spinlock);
1033                 if (ret < 0) {
1034                         mlog_errno(ret);
1035                         goto leave;
1036                 }
1037                 mlog(0, "%s:%.*s: restart lock mastery succeeded, "
1038                      "rechecking now\n", dlm->name, res->lockname.len,
1039                      res->lockname.name);
1040                 goto recheck;
1041         } else {
1042                 if (!voting_done) {
1043                         mlog(0, "map not changed and voting not done "
1044                              "for %s:%.*s\n", dlm->name, res->lockname.len,
1045                              res->lockname.name);
1046                 }
1047         }
1048
1049         if (m != O2NM_MAX_NODES) {
1050                 /* another node has done an assert!
1051                  * all done! */
1052                 sleep = 0;
1053         } else {
1054                 sleep = 1;
1055                 /* have all nodes responded? */
1056                 if (voting_done && !*blocked) {
1057                         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
1058                         if (dlm->node_num <= bit) {
1059                                 /* my node number is lowest.
1060                                  * now tell other nodes that I am
1061                                  * mastering this. */
1062                                 mle->master = dlm->node_num;
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, "waiting again\n");
1089                         goto recheck;
1090                 }
1091                 mlog(0, "done waiting, master is %u\n", res->owner);
1092                 ret = 0;
1093                 goto leave;
1094         }
1095
1096         ret = 0;   /* done */
1097         if (assert) {
1098                 m = dlm->node_num;
1099                 mlog(0, "about to master %.*s here, this=%u\n",
1100                      res->lockname.len, res->lockname.name, m);
1101                 ret = dlm_do_assert_master(dlm, res->lockname.name,
1102                                            res->lockname.len, 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         dlm_change_lockres_owner(dlm, res, m);
1119         spin_unlock(&res->spinlock);
1120
1121 leave:
1122         return ret;
1123 }
1124
1125 struct dlm_bitmap_diff_iter
1126 {
1127         int curnode;
1128         unsigned long *orig_bm;
1129         unsigned long *cur_bm;
1130         unsigned long diff_bm[BITS_TO_LONGS(O2NM_MAX_NODES)];
1131 };
1132
1133 enum dlm_node_state_change
1134 {
1135         NODE_DOWN = -1,
1136         NODE_NO_CHANGE = 0,
1137         NODE_UP
1138 };
1139
1140 static void dlm_bitmap_diff_iter_init(struct dlm_bitmap_diff_iter *iter,
1141                                       unsigned long *orig_bm,
1142                                       unsigned long *cur_bm)
1143 {
1144         unsigned long p1, p2;
1145         int i;
1146
1147         iter->curnode = -1;
1148         iter->orig_bm = orig_bm;
1149         iter->cur_bm = cur_bm;
1150
1151         for (i = 0; i < BITS_TO_LONGS(O2NM_MAX_NODES); i++) {
1152                 p1 = *(iter->orig_bm + i);
1153                 p2 = *(iter->cur_bm + i);
1154                 iter->diff_bm[i] = (p1 & ~p2) | (p2 & ~p1);
1155         }
1156 }
1157
1158 static int dlm_bitmap_diff_iter_next(struct dlm_bitmap_diff_iter *iter,
1159                                      enum dlm_node_state_change *state)
1160 {
1161         int bit;
1162
1163         if (iter->curnode >= O2NM_MAX_NODES)
1164                 return -ENOENT;
1165
1166         bit = find_next_bit(iter->diff_bm, O2NM_MAX_NODES,
1167                             iter->curnode+1);
1168         if (bit >= O2NM_MAX_NODES) {
1169                 iter->curnode = O2NM_MAX_NODES;
1170                 return -ENOENT;
1171         }
1172
1173         /* if it was there in the original then this node died */
1174         if (test_bit(bit, iter->orig_bm))
1175                 *state = NODE_DOWN;
1176         else
1177                 *state = NODE_UP;
1178
1179         iter->curnode = bit;
1180         return bit;
1181 }
1182
1183
1184 static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
1185                                     struct dlm_lock_resource *res,
1186                                     struct dlm_master_list_entry *mle,
1187                                     int blocked)
1188 {
1189         struct dlm_bitmap_diff_iter bdi;
1190         enum dlm_node_state_change sc;
1191         int node;
1192         int ret = 0;
1193
1194         mlog(0, "something happened such that the "
1195              "master process may need to be restarted!\n");
1196
1197         assert_spin_locked(&mle->spinlock);
1198
1199         dlm_bitmap_diff_iter_init(&bdi, mle->vote_map, mle->node_map);
1200         node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1201         while (node >= 0) {
1202                 if (sc == NODE_UP) {
1203                         /* a node came up.  clear any old vote from
1204                          * the response map and set it in the vote map
1205                          * then restart the mastery. */
1206                         mlog(ML_NOTICE, "node %d up while restarting\n", node);
1207
1208                         /* redo the master request, but only for the new node */
1209                         mlog(0, "sending request to new node\n");
1210                         clear_bit(node, mle->response_map);
1211                         set_bit(node, mle->vote_map);
1212                 } else {
1213                         mlog(ML_ERROR, "node down! %d\n", node);
1214                         if (blocked) {
1215                                 int lowest = find_next_bit(mle->maybe_map,
1216                                                        O2NM_MAX_NODES, 0);
1217
1218                                 /* act like it was never there */
1219                                 clear_bit(node, mle->maybe_map);
1220
1221                                 if (node == lowest) {
1222                                         mlog(0, "expected master %u died"
1223                                             " while this node was blocked "
1224                                             "waiting on it!\n", node);
1225                                         lowest = find_next_bit(mle->maybe_map,
1226                                                         O2NM_MAX_NODES,
1227                                                         lowest+1);
1228                                         if (lowest < O2NM_MAX_NODES) {
1229                                                 mlog(0, "%s:%.*s:still "
1230                                                      "blocked. waiting on %u "
1231                                                      "now\n", dlm->name,
1232                                                      res->lockname.len,
1233                                                      res->lockname.name,
1234                                                      lowest);
1235                                         } else {
1236                                                 /* mle is an MLE_BLOCK, but
1237                                                  * there is now nothing left to
1238                                                  * block on.  we need to return
1239                                                  * all the way back out and try
1240                                                  * again with an MLE_MASTER.
1241                                                  * dlm_do_local_recovery_cleanup
1242                                                  * has already run, so the mle
1243                                                  * refcount is ok */
1244                                                 mlog(0, "%s:%.*s: no "
1245                                                      "longer blocking. try to "
1246                                                      "master this here\n",
1247                                                      dlm->name,
1248                                                      res->lockname.len,
1249                                                      res->lockname.name);
1250                                                 mle->type = DLM_MLE_MASTER;
1251                                                 mle->u.res = res;
1252                                         }
1253                                 }
1254                         }
1255
1256                         /* now blank out everything, as if we had never
1257                          * contacted anyone */
1258                         memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
1259                         memset(mle->response_map, 0, sizeof(mle->response_map));
1260                         /* reset the vote_map to the current node_map */
1261                         memcpy(mle->vote_map, mle->node_map,
1262                                sizeof(mle->node_map));
1263                         /* put myself into the maybe map */
1264                         if (mle->type != DLM_MLE_BLOCK)
1265                                 set_bit(dlm->node_num, mle->maybe_map);
1266                 }
1267                 ret = -EAGAIN;
1268                 node = dlm_bitmap_diff_iter_next(&bdi, &sc);
1269         }
1270         return ret;
1271 }
1272
1273
1274 /*
1275  * DLM_MASTER_REQUEST_MSG
1276  *
1277  * returns: 0 on success,
1278  *          -errno on a network error
1279  *
1280  * on error, the caller should assume the target node is "dead"
1281  *
1282  */
1283
1284 static int dlm_do_master_request(struct dlm_master_list_entry *mle, int to)
1285 {
1286         struct dlm_ctxt *dlm = mle->dlm;
1287         struct dlm_master_request request;
1288         int ret, response=0, resend;
1289
1290         memset(&request, 0, sizeof(request));
1291         request.node_idx = dlm->node_num;
1292
1293         BUG_ON(mle->type == DLM_MLE_MIGRATION);
1294
1295         if (mle->type != DLM_MLE_MASTER) {
1296                 request.namelen = mle->u.name.len;
1297                 memcpy(request.name, mle->u.name.name, request.namelen);
1298         } else {
1299                 request.namelen = mle->u.res->lockname.len;
1300                 memcpy(request.name, mle->u.res->lockname.name,
1301                         request.namelen);
1302         }
1303
1304 again:
1305         ret = o2net_send_message(DLM_MASTER_REQUEST_MSG, dlm->key, &request,
1306                                  sizeof(request), to, &response);
1307         if (ret < 0)  {
1308                 if (ret == -ESRCH) {
1309                         /* should never happen */
1310                         mlog(ML_ERROR, "TCP stack not ready!\n");
1311                         BUG();
1312                 } else if (ret == -EINVAL) {
1313                         mlog(ML_ERROR, "bad args passed to o2net!\n");
1314                         BUG();
1315                 } else if (ret == -ENOMEM) {
1316                         mlog(ML_ERROR, "out of memory while trying to send "
1317                              "network message!  retrying\n");
1318                         /* this is totally crude */
1319                         msleep(50);
1320                         goto again;
1321                 } else if (!dlm_is_host_down(ret)) {
1322                         /* not a network error. bad. */
1323                         mlog_errno(ret);
1324                         mlog(ML_ERROR, "unhandled error!");
1325                         BUG();
1326                 }
1327                 /* all other errors should be network errors,
1328                  * and likely indicate node death */
1329                 mlog(ML_ERROR, "link to %d went down!\n", to);
1330                 goto out;
1331         }
1332
1333         ret = 0;
1334         resend = 0;
1335         spin_lock(&mle->spinlock);
1336         switch (response) {
1337                 case DLM_MASTER_RESP_YES:
1338                         set_bit(to, mle->response_map);
1339                         mlog(0, "node %u is the master, response=YES\n", 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 {
1382         u8 response = DLM_MASTER_RESP_MAYBE;
1383         struct dlm_ctxt *dlm = data;
1384         struct dlm_lock_resource *res = NULL;
1385         struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
1386         struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
1387         char *name;
1388         unsigned int namelen, hash;
1389         int found, ret;
1390         int set_maybe;
1391         int dispatch_assert = 0;
1392
1393         if (!dlm_grab(dlm))
1394                 return DLM_MASTER_RESP_NO;
1395
1396         if (!dlm_domain_fully_joined(dlm)) {
1397                 response = DLM_MASTER_RESP_NO;
1398                 goto send_response;
1399         }
1400
1401         name = request->name;
1402         namelen = request->namelen;
1403         hash = dlm_lockid_hash(name, namelen);
1404
1405         if (namelen > DLM_LOCKID_NAME_MAX) {
1406                 response = DLM_IVBUFLEN;
1407                 goto send_response;
1408         }
1409
1410 way_up_top:
1411         spin_lock(&dlm->spinlock);
1412         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
1413         if (res) {
1414                 spin_unlock(&dlm->spinlock);
1415
1416                 /* take care of the easy cases up front */
1417                 spin_lock(&res->spinlock);
1418                 if (res->state & DLM_LOCK_RES_RECOVERING) {
1419                         spin_unlock(&res->spinlock);
1420                         mlog(0, "returning DLM_MASTER_RESP_ERROR since res is "
1421                              "being recovered\n");
1422                         response = DLM_MASTER_RESP_ERROR;
1423                         if (mle)
1424                                 kmem_cache_free(dlm_mle_cache, mle);
1425                         goto send_response;
1426                 }
1427
1428                 if (res->owner == dlm->node_num) {
1429                         spin_unlock(&res->spinlock);
1430                         // mlog(0, "this node is the master\n");
1431                         response = DLM_MASTER_RESP_YES;
1432                         if (mle)
1433                                 kmem_cache_free(dlm_mle_cache, mle);
1434
1435                         /* this node is the owner.
1436                          * there is some extra work that needs to
1437                          * happen now.  the requesting node has
1438                          * caused all nodes up to this one to
1439                          * create mles.  this node now needs to
1440                          * go back and clean those up. */
1441                         dispatch_assert = 1;
1442                         goto send_response;
1443                 } else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1444                         spin_unlock(&res->spinlock);
1445                         // mlog(0, "node %u is the master\n", res->owner);
1446                         response = DLM_MASTER_RESP_NO;
1447                         if (mle)
1448                                 kmem_cache_free(dlm_mle_cache, mle);
1449                         goto send_response;
1450                 }
1451
1452                 /* ok, there is no owner.  either this node is
1453                  * being blocked, or it is actively trying to
1454                  * master this lock. */
1455                 if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1456                         mlog(ML_ERROR, "lock with no owner should be "
1457                              "in-progress!\n");
1458                         BUG();
1459                 }
1460
1461                 // mlog(0, "lockres is in progress...\n");
1462                 spin_lock(&dlm->master_lock);
1463                 found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1464                 if (!found) {
1465                         mlog(ML_ERROR, "no mle found for this lock!\n");
1466                         BUG();
1467                 }
1468                 set_maybe = 1;
1469                 spin_lock(&tmpmle->spinlock);
1470                 if (tmpmle->type == DLM_MLE_BLOCK) {
1471                         // mlog(0, "this node is waiting for "
1472                         // "lockres to be mastered\n");
1473                         response = DLM_MASTER_RESP_NO;
1474                 } else if (tmpmle->type == DLM_MLE_MIGRATION) {
1475                         mlog(0, "node %u is master, but trying to migrate to "
1476                              "node %u.\n", tmpmle->master, tmpmle->new_master);
1477                         if (tmpmle->master == dlm->node_num) {
1478                                 response = DLM_MASTER_RESP_YES;
1479                                 mlog(ML_ERROR, "no owner on lockres, but this "
1480                                      "node is trying to migrate it to %u?!\n",
1481                                      tmpmle->new_master);
1482                                 BUG();
1483                         } else {
1484                                 /* the real master can respond on its own */
1485                                 response = DLM_MASTER_RESP_NO;
1486                         }
1487                 } else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
1488                         set_maybe = 0;
1489                         if (tmpmle->master == dlm->node_num) {
1490                                 response = DLM_MASTER_RESP_YES;
1491                                 /* this node will be the owner.
1492                                  * go back and clean the mles on any
1493                                  * other nodes */
1494                                 dispatch_assert = 1;
1495                         } else
1496                                 response = DLM_MASTER_RESP_NO;
1497                 } else {
1498                         // mlog(0, "this node is attempting to "
1499                         // "master lockres\n");
1500                         response = DLM_MASTER_RESP_MAYBE;
1501                 }
1502                 if (set_maybe)
1503                         set_bit(request->node_idx, tmpmle->maybe_map);
1504                 spin_unlock(&tmpmle->spinlock);
1505
1506                 spin_unlock(&dlm->master_lock);
1507                 spin_unlock(&res->spinlock);
1508
1509                 /* keep the mle attached to heartbeat events */
1510                 dlm_put_mle(tmpmle);
1511                 if (mle)
1512                         kmem_cache_free(dlm_mle_cache, mle);
1513                 goto send_response;
1514         }
1515
1516         /*
1517          * lockres doesn't exist on this node
1518          * if there is an MLE_BLOCK, return NO
1519          * if there is an MLE_MASTER, return MAYBE
1520          * otherwise, add an MLE_BLOCK, return NO
1521          */
1522         spin_lock(&dlm->master_lock);
1523         found = dlm_find_mle(dlm, &tmpmle, name, namelen);
1524         if (!found) {
1525                 /* this lockid has never been seen on this node yet */
1526                 // mlog(0, "no mle found\n");
1527                 if (!mle) {
1528                         spin_unlock(&dlm->master_lock);
1529                         spin_unlock(&dlm->spinlock);
1530
1531                         mle = (struct dlm_master_list_entry *)
1532                                 kmem_cache_alloc(dlm_mle_cache, GFP_KERNEL);
1533                         if (!mle) {
1534                                 response = DLM_MASTER_RESP_ERROR;
1535                                 mlog_errno(-ENOMEM);
1536                                 goto send_response;
1537                         }
1538                         goto way_up_top;
1539                 }
1540
1541                 // mlog(0, "this is second time thru, already allocated, "
1542                 // "add the block.\n");
1543                 dlm_init_mle(mle, DLM_MLE_BLOCK, dlm, NULL, name, namelen);
1544                 set_bit(request->node_idx, mle->maybe_map);
1545                 list_add(&mle->list, &dlm->master_list);
1546                 response = DLM_MASTER_RESP_NO;
1547         } else {
1548                 // mlog(0, "mle was found\n");
1549                 set_maybe = 1;
1550                 spin_lock(&tmpmle->spinlock);
1551                 if (tmpmle->master == dlm->node_num) {
1552                         mlog(ML_ERROR, "no lockres, but an mle with this node as master!\n");
1553                         BUG();
1554                 }
1555                 if (tmpmle->type == DLM_MLE_BLOCK)
1556                         response = DLM_MASTER_RESP_NO;
1557                 else if (tmpmle->type == DLM_MLE_MIGRATION) {
1558                         mlog(0, "migration mle was found (%u->%u)\n",
1559                              tmpmle->master, tmpmle->new_master);
1560                         /* real master can respond on its own */
1561                         response = DLM_MASTER_RESP_NO;
1562                 } else
1563                         response = DLM_MASTER_RESP_MAYBE;
1564                 if (set_maybe)
1565                         set_bit(request->node_idx, tmpmle->maybe_map);
1566                 spin_unlock(&tmpmle->spinlock);
1567         }
1568         spin_unlock(&dlm->master_lock);
1569         spin_unlock(&dlm->spinlock);
1570
1571         if (found) {
1572                 /* keep the mle attached to heartbeat events */
1573                 dlm_put_mle(tmpmle);
1574         }
1575 send_response:
1576
1577         if (dispatch_assert) {
1578                 if (response != DLM_MASTER_RESP_YES)
1579                         mlog(ML_ERROR, "invalid response %d\n", response);
1580                 if (!res) {
1581                         mlog(ML_ERROR, "bad lockres while trying to assert!\n");
1582                         BUG();
1583                 }
1584                 mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
1585                              dlm->node_num, res->lockname.len, res->lockname.name);
1586                 ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx,
1587                                                  DLM_ASSERT_MASTER_MLE_CLEANUP);
1588                 if (ret < 0) {
1589                         mlog(ML_ERROR, "failed to dispatch assert master work\n");
1590                         response = DLM_MASTER_RESP_ERROR;
1591                 }
1592         }
1593
1594         dlm_put(dlm);
1595         return response;
1596 }
1597
1598 /*
1599  * DLM_ASSERT_MASTER_MSG
1600  */
1601
1602
1603 /*
1604  * NOTE: this can be used for debugging
1605  * can periodically run all locks owned by this node
1606  * and re-assert across the cluster...
1607  */
1608 static int dlm_do_assert_master(struct dlm_ctxt *dlm, const char *lockname,
1609                                 unsigned int namelen, void *nodemap,
1610                                 u32 flags)
1611 {
1612         struct dlm_assert_master assert;
1613         int to, tmpret;
1614         struct dlm_node_iter iter;
1615         int ret = 0;
1616         int reassert;
1617
1618         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
1619 again:
1620         reassert = 0;
1621
1622         /* note that if this nodemap is empty, it returns 0 */
1623         dlm_node_iter_init(nodemap, &iter);
1624         while ((to = dlm_node_iter_next(&iter)) >= 0) {
1625                 int r = 0;
1626                 struct dlm_master_list_entry *mle = NULL;
1627
1628                 mlog(0, "sending assert master to %d (%.*s)\n", to,
1629                      namelen, lockname);
1630                 memset(&assert, 0, sizeof(assert));
1631                 assert.node_idx = dlm->node_num;
1632                 assert.namelen = namelen;
1633                 memcpy(assert.name, lockname, namelen);
1634                 assert.flags = cpu_to_be32(flags);
1635
1636                 tmpret = o2net_send_message(DLM_ASSERT_MASTER_MSG, dlm->key,
1637                                             &assert, sizeof(assert), to, &r);
1638                 if (tmpret < 0) {
1639                         mlog(ML_ERROR, "assert_master returned %d!\n", tmpret);
1640                         if (!dlm_is_host_down(tmpret)) {
1641                                 mlog(ML_ERROR, "unhandled error!\n");
1642                                 BUG();
1643                         }
1644                         /* a node died.  finish out the rest of the nodes. */
1645                         mlog(ML_ERROR, "link to %d went down!\n", to);
1646                         /* any nonzero status return will do */
1647                         ret = tmpret;
1648                 } else if (r < 0) {
1649                         /* ok, something horribly messed.  kill thyself. */
1650                         mlog(ML_ERROR,"during assert master of %.*s to %u, "
1651                              "got %d.\n", namelen, lockname, to, r);
1652                         spin_lock(&dlm->spinlock);
1653                         spin_lock(&dlm->master_lock);
1654                         if (dlm_find_mle(dlm, &mle, (char *)lockname,
1655                                          namelen)) {
1656                                 dlm_print_one_mle(mle);
1657                                 __dlm_put_mle(mle);
1658                         }
1659                         spin_unlock(&dlm->master_lock);
1660                         spin_unlock(&dlm->spinlock);
1661                         BUG();
1662                 } else if (r == EAGAIN) {
1663                         mlog(0, "%.*s: node %u create mles on other "
1664                              "nodes and requests a re-assert\n",
1665                              namelen, lockname, to);
1666                         reassert = 1;
1667                 }
1668         }
1669
1670         if (reassert)
1671                 goto again;
1672
1673         return ret;
1674 }
1675
1676 /*
1677  * locks that can be taken here:
1678  * dlm->spinlock
1679  * res->spinlock
1680  * mle->spinlock
1681  * dlm->master_list
1682  *
1683  * if possible, TRIM THIS DOWN!!!
1684  */
1685 int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data)
1686 {
1687         struct dlm_ctxt *dlm = data;
1688         struct dlm_master_list_entry *mle = NULL;
1689         struct dlm_assert_master *assert = (struct dlm_assert_master *)msg->buf;
1690         struct dlm_lock_resource *res = NULL;
1691         char *name;
1692         unsigned int namelen, hash;
1693         u32 flags;
1694         int master_request = 0;
1695         int ret = 0;
1696
1697         if (!dlm_grab(dlm))
1698                 return 0;
1699
1700         name = assert->name;
1701         namelen = assert->namelen;
1702         hash = dlm_lockid_hash(name, namelen);
1703         flags = be32_to_cpu(assert->flags);
1704
1705         if (namelen > DLM_LOCKID_NAME_MAX) {
1706                 mlog(ML_ERROR, "Invalid name length!");
1707                 goto done;
1708         }
1709
1710         spin_lock(&dlm->spinlock);
1711
1712         if (flags)
1713                 mlog(0, "assert_master with flags: %u\n", flags);
1714
1715         /* find the MLE */
1716         spin_lock(&dlm->master_lock);
1717         if (!dlm_find_mle(dlm, &mle, name, namelen)) {
1718                 /* not an error, could be master just re-asserting */
1719                 mlog(0, "just got an assert_master from %u, but no "
1720                      "MLE for it! (%.*s)\n", assert->node_idx,
1721                      namelen, name);
1722         } else {
1723                 int bit = find_next_bit (mle->maybe_map, O2NM_MAX_NODES, 0);
1724                 if (bit >= O2NM_MAX_NODES) {
1725                         /* not necessarily an error, though less likely.
1726                          * could be master just re-asserting. */
1727                         mlog(0, "no bits set in the maybe_map, but %u "
1728                              "is asserting! (%.*s)\n", assert->node_idx,
1729                              namelen, name);
1730                 } else if (bit != assert->node_idx) {
1731                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1732                                 mlog(0, "master %u was found, %u should "
1733                                      "back off\n", assert->node_idx, bit);
1734                         } else {
1735                                 /* with the fix for bug 569, a higher node
1736                                  * number winning the mastery will respond
1737                                  * YES to mastery requests, but this node
1738                                  * had no way of knowing.  let it pass. */
1739                                 mlog(0, "%u is the lowest node, "
1740                                      "%u is asserting. (%.*s)  %u must "
1741                                      "have begun after %u won.\n", bit,
1742                                      assert->node_idx, namelen, name, bit,
1743                                      assert->node_idx);
1744                         }
1745                 }
1746                 if (mle->type == DLM_MLE_MIGRATION) {
1747                         if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
1748                                 mlog(0, "%s:%.*s: got cleanup assert"
1749                                      " from %u for migration\n",
1750                                      dlm->name, namelen, name,
1751                                      assert->node_idx);
1752                         } else if (!(flags & DLM_ASSERT_MASTER_FINISH_MIGRATION)) {
1753                                 mlog(0, "%s:%.*s: got unrelated assert"
1754                                      " from %u for migration, ignoring\n",
1755                                      dlm->name, namelen, name,
1756                                      assert->node_idx);
1757                                 __dlm_put_mle(mle);
1758                                 spin_unlock(&dlm->master_lock);
1759                                 spin_unlock(&dlm->spinlock);
1760                                 goto done;
1761                         }
1762                 }
1763         }
1764         spin_unlock(&dlm->master_lock);
1765
1766         /* ok everything checks out with the MLE
1767          * now check to see if there is a lockres */
1768         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
1769         if (res) {
1770                 spin_lock(&res->spinlock);
1771                 if (res->state & DLM_LOCK_RES_RECOVERING)  {
1772                         mlog(ML_ERROR, "%u asserting but %.*s is "
1773                              "RECOVERING!\n", assert->node_idx, namelen, name);
1774                         goto kill;
1775                 }
1776                 if (!mle) {
1777                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN &&
1778                             res->owner != assert->node_idx) {
1779                                 mlog(ML_ERROR, "assert_master from "
1780                                           "%u, but current owner is "
1781                                           "%u! (%.*s)\n",
1782                                        assert->node_idx, res->owner,
1783                                        namelen, name);
1784                                 goto kill;
1785                         }
1786                 } else if (mle->type != DLM_MLE_MIGRATION) {
1787                         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
1788                                 /* owner is just re-asserting */
1789                                 if (res->owner == assert->node_idx) {
1790                                         mlog(0, "owner %u re-asserting on "
1791                                              "lock %.*s\n", assert->node_idx,
1792                                              namelen, name);
1793                                         goto ok;
1794                                 }
1795                                 mlog(ML_ERROR, "got assert_master from "
1796                                      "node %u, but %u is the owner! "
1797                                      "(%.*s)\n", assert->node_idx,
1798                                      res->owner, namelen, name);
1799                                 goto kill;
1800                         }
1801                         if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
1802                                 mlog(ML_ERROR, "got assert from %u, but lock "
1803                                      "with no owner should be "
1804                                      "in-progress! (%.*s)\n",
1805                                      assert->node_idx,
1806                                      namelen, name);
1807                                 goto kill;
1808                         }
1809                 } else /* mle->type == DLM_MLE_MIGRATION */ {
1810                         /* should only be getting an assert from new master */
1811                         if (assert->node_idx != mle->new_master) {
1812                                 mlog(ML_ERROR, "got assert from %u, but "
1813                                      "new master is %u, and old master "
1814                                      "was %u (%.*s)\n",
1815                                      assert->node_idx, mle->new_master,
1816                                      mle->master, namelen, name);
1817                                 goto kill;
1818                         }
1819
1820                 }
1821 ok:
1822                 spin_unlock(&res->spinlock);
1823         }
1824         spin_unlock(&dlm->spinlock);
1825
1826         // mlog(0, "woo!  got an assert_master from node %u!\n",
1827         //           assert->node_idx);
1828         if (mle) {
1829                 int extra_ref = 0;
1830                 int nn = -1;
1831                 int rr, err = 0;
1832
1833                 spin_lock(&mle->spinlock);
1834                 if (mle->type == DLM_MLE_BLOCK || mle->type == DLM_MLE_MIGRATION)
1835                         extra_ref = 1;
1836                 else {
1837                         /* MASTER mle: if any bits set in the response map
1838                          * then the calling node needs to re-assert to clear
1839                          * up nodes that this node contacted */
1840                         while ((nn = find_next_bit (mle->response_map, O2NM_MAX_NODES,
1841                                                     nn+1)) < O2NM_MAX_NODES) {
1842                                 if (nn != dlm->node_num && nn != assert->node_idx)
1843                                         master_request = 1;
1844                         }
1845                 }
1846                 mle->master = assert->node_idx;
1847                 atomic_set(&mle->woken, 1);
1848                 wake_up(&mle->wq);
1849                 spin_unlock(&mle->spinlock);
1850
1851                 if (res) {
1852                         spin_lock(&res->spinlock);
1853                         if (mle->type == DLM_MLE_MIGRATION) {
1854                                 mlog(0, "finishing off migration of lockres %.*s, "
1855                                         "from %u to %u\n",
1856                                         res->lockname.len, res->lockname.name,
1857                                         dlm->node_num, mle->new_master);
1858                                 res->state &= ~DLM_LOCK_RES_MIGRATING;
1859                                 dlm_change_lockres_owner(dlm, res, mle->new_master);
1860                                 BUG_ON(res->state & DLM_LOCK_RES_DIRTY);
1861                         } else {
1862                                 dlm_change_lockres_owner(dlm, res, mle->master);
1863                         }
1864                         spin_unlock(&res->spinlock);
1865                 }
1866
1867                 /* master is known, detach if not already detached.
1868                  * ensures that only one assert_master call will happen
1869                  * on this mle. */
1870                 spin_lock(&dlm->spinlock);
1871                 spin_lock(&dlm->master_lock);
1872
1873                 rr = atomic_read(&mle->mle_refs.refcount);
1874                 if (mle->inuse > 0) {
1875                         if (extra_ref && rr < 3)
1876                                 err = 1;
1877                         else if (!extra_ref && rr < 2)
1878                                 err = 1;
1879                 } else {
1880                         if (extra_ref && rr < 2)
1881                                 err = 1;
1882                         else if (!extra_ref && rr < 1)
1883                                 err = 1;
1884                 }
1885                 if (err) {
1886                         mlog(ML_ERROR, "%s:%.*s: got assert master from %u "
1887                              "that will mess up this node, refs=%d, extra=%d, "
1888                              "inuse=%d\n", dlm->name, namelen, name,
1889                              assert->node_idx, rr, extra_ref, mle->inuse);
1890                         dlm_print_one_mle(mle);
1891                 }
1892                 list_del_init(&mle->list);
1893                 __dlm_mle_detach_hb_events(dlm, mle);
1894                 __dlm_put_mle(mle);
1895                 if (extra_ref) {
1896                         /* the assert master message now balances the extra
1897                          * ref given by the master / migration request message.
1898                          * if this is the last put, it will be removed
1899                          * from the list. */
1900                         __dlm_put_mle(mle);
1901                 }
1902                 spin_unlock(&dlm->master_lock);
1903                 spin_unlock(&dlm->spinlock);
1904         } else if (res) {
1905                 if (res->owner != assert->node_idx) {
1906                         mlog(0, "assert_master from %u, but current "
1907                              "owner is %u (%.*s), no mle\n", assert->node_idx,
1908                              res->owner, namelen, name);
1909                 }
1910         }
1911
1912 done:
1913         ret = 0;
1914         if (res)
1915                 dlm_lockres_put(res);
1916         dlm_put(dlm);
1917         if (master_request) {
1918                 mlog(0, "need to tell master to reassert\n");
1919                 ret = EAGAIN;  // positive. negative would shoot down the node.
1920         }
1921         return ret;
1922
1923 kill:
1924         /* kill the caller! */
1925         mlog(ML_ERROR, "Bad message received from another node.  Dumping state "
1926              "and killing the other node now!  This node is OK and can continue.\n");
1927         __dlm_print_one_lock_resource(res);
1928         spin_unlock(&res->spinlock);
1929         spin_unlock(&dlm->spinlock);
1930         dlm_lockres_put(res);
1931         dlm_put(dlm);
1932         return -EINVAL;
1933 }
1934
1935 int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
1936                                struct dlm_lock_resource *res,
1937                                int ignore_higher, u8 request_from, u32 flags)
1938 {
1939         struct dlm_work_item *item;
1940         item = kcalloc(1, sizeof(*item), GFP_KERNEL);
1941         if (!item)
1942                 return -ENOMEM;
1943
1944
1945         /* queue up work for dlm_assert_master_worker */
1946         dlm_grab(dlm);  /* get an extra ref for the work item */
1947         dlm_init_work_item(dlm, item, dlm_assert_master_worker, NULL);
1948         item->u.am.lockres = res; /* already have a ref */
1949         /* can optionally ignore node numbers higher than this node */
1950         item->u.am.ignore_higher = ignore_higher;
1951         item->u.am.request_from = request_from;
1952         item->u.am.flags = flags;
1953
1954         if (ignore_higher)
1955                 mlog(0, "IGNORE HIGHER: %.*s\n", res->lockname.len,
1956                      res->lockname.name);
1957
1958         spin_lock(&dlm->work_lock);
1959         list_add_tail(&item->list, &dlm->work_list);
1960         spin_unlock(&dlm->work_lock);
1961
1962         schedule_work(&dlm->dispatched_work);
1963         return 0;
1964 }
1965
1966 static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
1967 {
1968         struct dlm_ctxt *dlm = data;
1969         int ret = 0;
1970         struct dlm_lock_resource *res;
1971         unsigned long nodemap[BITS_TO_LONGS(O2NM_MAX_NODES)];
1972         int ignore_higher;
1973         int bit;
1974         u8 request_from;
1975         u32 flags;
1976
1977         dlm = item->dlm;
1978         res = item->u.am.lockres;
1979         ignore_higher = item->u.am.ignore_higher;
1980         request_from = item->u.am.request_from;
1981         flags = item->u.am.flags;
1982
1983         spin_lock(&dlm->spinlock);
1984         memcpy(nodemap, dlm->domain_map, sizeof(nodemap));
1985         spin_unlock(&dlm->spinlock);
1986
1987         clear_bit(dlm->node_num, nodemap);
1988         if (ignore_higher) {
1989                 /* if is this just to clear up mles for nodes below
1990                  * this node, do not send the message to the original
1991                  * caller or any node number higher than this */
1992                 clear_bit(request_from, nodemap);
1993                 bit = dlm->node_num;
1994                 while (1) {
1995                         bit = find_next_bit(nodemap, O2NM_MAX_NODES,
1996                                             bit+1);
1997                         if (bit >= O2NM_MAX_NODES)
1998                                 break;
1999                         clear_bit(bit, nodemap);
2000                 }
2001         }
2002
2003         /* this call now finishes out the nodemap
2004          * even if one or more nodes die */
2005         mlog(0, "worker about to master %.*s here, this=%u\n",
2006                      res->lockname.len, res->lockname.name, dlm->node_num);
2007         ret = dlm_do_assert_master(dlm, res->lockname.name,
2008                                    res->lockname.len,
2009                                    nodemap, flags);
2010         if (ret < 0) {
2011                 /* no need to restart, we are done */
2012                 mlog_errno(ret);
2013         }
2014
2015         dlm_lockres_put(res);
2016
2017         mlog(0, "finished with dlm_assert_master_worker\n");
2018 }
2019
2020 /* SPECIAL CASE for the $RECOVERY lock used by the recovery thread.
2021  * We cannot wait for node recovery to complete to begin mastering this
2022  * lockres because this lockres is used to kick off recovery! ;-)
2023  * So, do a pre-check on all living nodes to see if any of those nodes
2024  * think that $RECOVERY is currently mastered by a dead node.  If so,
2025  * we wait a short time to allow that node to get notified by its own
2026  * heartbeat stack, then check again.  All $RECOVERY lock resources
2027  * mastered by dead nodes are purged when the hearbeat callback is
2028  * fired, so we can know for sure that it is safe to continue once
2029  * the node returns a live node or no node.  */
2030 static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
2031                                        struct dlm_lock_resource *res)
2032 {
2033         struct dlm_node_iter iter;
2034         int nodenum;
2035         int ret = 0;
2036         u8 master = DLM_LOCK_RES_OWNER_UNKNOWN;
2037
2038         spin_lock(&dlm->spinlock);
2039         dlm_node_iter_init(dlm->domain_map, &iter);
2040         spin_unlock(&dlm->spinlock);
2041
2042         while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
2043                 /* do not send to self */
2044                 if (nodenum == dlm->node_num)
2045                         continue;
2046                 ret = dlm_do_master_requery(dlm, res, nodenum, &master);
2047                 if (ret < 0) {
2048                         mlog_errno(ret);
2049                         if (!dlm_is_host_down(ret))
2050                                 BUG();
2051                         /* host is down, so answer for that node would be
2052                          * DLM_LOCK_RES_OWNER_UNKNOWN.  continue. */
2053                         ret = 0;
2054                 }
2055
2056                 if (master != DLM_LOCK_RES_OWNER_UNKNOWN) {
2057                         /* check to see if this master is in the recovery map */
2058                         spin_lock(&dlm->spinlock);
2059                         if (test_bit(master, dlm->recovery_map)) {
2060                                 mlog(ML_NOTICE, "%s: node %u has not seen "
2061                                      "node %u go down yet, and thinks the "
2062                                      "dead node is mastering the recovery "
2063                                      "lock.  must wait.\n", dlm->name,
2064                                      nodenum, master);
2065                                 ret = -EAGAIN;
2066                         }
2067                         spin_unlock(&dlm->spinlock);
2068                         mlog(0, "%s: reco lock master is %u\n", dlm->name,
2069                              master);
2070                         break;
2071                 }
2072         }
2073         return ret;
2074 }
2075
2076
2077 /*
2078  * DLM_MIGRATE_LOCKRES
2079  */
2080
2081
2082 int dlm_migrate_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
2083                         u8 target)
2084 {
2085         struct dlm_master_list_entry *mle = NULL;
2086         struct dlm_master_list_entry *oldmle = NULL;
2087         struct dlm_migratable_lockres *mres = NULL;
2088         int ret = -EINVAL;
2089         const char *name;
2090         unsigned int namelen;
2091         int mle_added = 0;
2092         struct list_head *queue, *iter;
2093         int i;
2094         struct dlm_lock *lock;
2095         int empty = 1;
2096
2097         if (!dlm_grab(dlm))
2098                 return -EINVAL;
2099
2100         name = res->lockname.name;
2101         namelen = res->lockname.len;
2102
2103         mlog(0, "migrating %.*s to %u\n", namelen, name, target);
2104
2105         /*
2106          * ensure this lockres is a proper candidate for migration
2107          */
2108         spin_lock(&res->spinlock);
2109         if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
2110                 mlog(0, "cannot migrate lockres with unknown owner!\n");
2111                 spin_unlock(&res->spinlock);
2112                 goto leave;
2113         }
2114         if (res->owner != dlm->node_num) {
2115                 mlog(0, "cannot migrate lockres this node doesn't own!\n");
2116                 spin_unlock(&res->spinlock);
2117                 goto leave;
2118         }
2119         mlog(0, "checking queues...\n");
2120         queue = &res->granted;
2121         for (i=0; i<3; i++) {
2122                 list_for_each(iter, queue) {
2123                         lock = list_entry (iter, struct dlm_lock, list);
2124                         empty = 0;
2125                         if (lock->ml.node == dlm->node_num) {
2126                                 mlog(0, "found a lock owned by this node "
2127                                      "still on the %s queue!  will not "
2128                                      "migrate this lockres\n",
2129                                      i==0 ? "granted" :
2130                                      (i==1 ? "converting" : "blocked"));
2131                                 spin_unlock(&res->spinlock);
2132                                 ret = -ENOTEMPTY;
2133                                 goto leave;
2134                         }
2135                 }
2136                 queue++;
2137         }
2138         mlog(0, "all locks on this lockres are nonlocal.  continuing\n");
2139         spin_unlock(&res->spinlock);
2140
2141         /* no work to do */
2142         if (empty) {
2143                 mlog(0, "no locks were found on this lockres! done!\n");
2144                 ret = 0;
2145                 goto leave;
2146         }
2147
2148         /*
2149          * preallocate up front
2150          * if this fails, abort
2151          */
2152
2153         ret = -ENOMEM;
2154         mres = (struct dlm_migratable_lockres *) __get_free_page(GFP_KERNEL);
2155         if (!mres) {
2156                 mlog_errno(ret);
2157                 goto leave;
2158         }
2159
2160         mle = (struct dlm_master_list_entry *) kmem_cache_alloc(dlm_mle_cache,
2161                                                                 GFP_KERNEL);
2162         if (!mle) {
2163                 mlog_errno(ret);
2164                 goto leave;
2165         }
2166         ret = 0;
2167
2168         /*
2169          * find a node to migrate the lockres to
2170          */
2171
2172         mlog(0, "picking a migration node\n");
2173         spin_lock(&dlm->spinlock);
2174         /* pick a new node */
2175         if (!test_bit(target, dlm->domain_map) ||
2176             target >= O2NM_MAX_NODES) {
2177                 target = dlm_pick_migration_target(dlm, res);
2178         }
2179         mlog(0, "node %u chosen for migration\n", target);
2180
2181         if (target >= O2NM_MAX_NODES ||
2182             !test_bit(target, dlm->domain_map)) {
2183                 /* target chosen is not alive */
2184                 ret = -EINVAL;
2185         }
2186
2187         if (ret) {
2188                 spin_unlock(&dlm->spinlock);
2189                 goto fail;
2190         }
2191
2192         mlog(0, "continuing with target = %u\n", target);
2193
2194         /*
2195          * clear any existing master requests and
2196          * add the migration mle to the list
2197          */
2198         spin_lock(&dlm->master_lock);
2199         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
2200                                     namelen, target, dlm->node_num);
2201         spin_unlock(&dlm->master_lock);
2202         spin_unlock(&dlm->spinlock);
2203
2204         if (ret == -EEXIST) {
2205                 mlog(0, "another process is already migrating it\n");
2206                 goto fail;
2207         }
2208         mle_added = 1;
2209
2210         /*
2211          * set the MIGRATING flag and flush asts
2212          * if we fail after this we need to re-dirty the lockres
2213          */
2214         if (dlm_mark_lockres_migrating(dlm, res, target) < 0) {
2215                 mlog(ML_ERROR, "tried to migrate %.*s to %u, but "
2216                      "the target went down.\n", res->lockname.len,
2217                      res->lockname.name, target);
2218                 spin_lock(&res->spinlock);
2219                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2220                 spin_unlock(&res->spinlock);
2221                 ret = -EINVAL;
2222         }
2223
2224 fail:
2225         if (oldmle) {
2226                 /* master is known, detach if not already detached */
2227                 dlm_mle_detach_hb_events(dlm, oldmle);
2228                 dlm_put_mle(oldmle);
2229         }
2230
2231         if (ret < 0) {
2232                 if (mle_added) {
2233                         dlm_mle_detach_hb_events(dlm, mle);
2234                         dlm_put_mle(mle);
2235                 } else if (mle) {
2236                         kmem_cache_free(dlm_mle_cache, mle);
2237                 }
2238                 goto leave;
2239         }
2240
2241         /*
2242          * at this point, we have a migration target, an mle
2243          * in the master list, and the MIGRATING flag set on
2244          * the lockres
2245          */
2246
2247
2248         /* get an extra reference on the mle.
2249          * otherwise the assert_master from the new
2250          * master will destroy this.
2251          * also, make sure that all callers of dlm_get_mle
2252          * take both dlm->spinlock and dlm->master_lock */
2253         spin_lock(&dlm->spinlock);
2254         spin_lock(&dlm->master_lock);
2255         dlm_get_mle_inuse(mle);
2256         spin_unlock(&dlm->master_lock);
2257         spin_unlock(&dlm->spinlock);
2258
2259         /* notify new node and send all lock state */
2260         /* call send_one_lockres with migration flag.
2261          * this serves as notice to the target node that a
2262          * migration is starting. */
2263         ret = dlm_send_one_lockres(dlm, res, mres, target,
2264                                    DLM_MRES_MIGRATION);
2265
2266         if (ret < 0) {
2267                 mlog(0, "migration to node %u failed with %d\n",
2268                      target, ret);
2269                 /* migration failed, detach and clean up mle */
2270                 dlm_mle_detach_hb_events(dlm, mle);
2271                 dlm_put_mle(mle);
2272                 dlm_put_mle_inuse(mle);
2273                 spin_lock(&res->spinlock);
2274                 res->state &= ~DLM_LOCK_RES_MIGRATING;
2275                 spin_unlock(&res->spinlock);
2276                 goto leave;
2277         }
2278
2279         /* at this point, the target sends a message to all nodes,
2280          * (using dlm_do_migrate_request).  this node is skipped since
2281          * we had to put an mle in the list to begin the process.  this
2282          * node now waits for target to do an assert master.  this node
2283          * will be the last one notified, ensuring that the migration
2284          * is complete everywhere.  if the target dies while this is
2285          * going on, some nodes could potentially see the target as the
2286          * master, so it is important that my recovery finds the migration
2287          * mle and sets the master to UNKNONWN. */
2288
2289
2290         /* wait for new node to assert master */
2291         while (1) {
2292                 ret = wait_event_interruptible_timeout(mle->wq,
2293                                         (atomic_read(&mle->woken) == 1),
2294                                         msecs_to_jiffies(5000));
2295
2296                 if (ret >= 0) {
2297                         if (atomic_read(&mle->woken) == 1 ||
2298                             res->owner == target)
2299                                 break;
2300
2301                         mlog(0, "timed out during migration\n");
2302                         /* avoid hang during shutdown when migrating lockres
2303                          * to a node which also goes down */
2304                         if (dlm_is_node_dead(dlm, target)) {
2305                                 mlog(0, "%s:%.*s: expected migration "
2306                                      "target %u is no longer up, restarting\n",
2307                                      dlm->name, res->lockname.len,
2308                                      res->lockname.name, target);
2309                                 ret = -ERESTARTSYS;
2310                         }
2311                 }
2312                 if (ret == -ERESTARTSYS) {
2313                         /* migration failed, detach and clean up mle */
2314                         dlm_mle_detach_hb_events(dlm, mle);
2315                         dlm_put_mle(mle);
2316                         dlm_put_mle_inuse(mle);
2317                         spin_lock(&res->spinlock);
2318                         res->state &= ~DLM_LOCK_RES_MIGRATING;
2319                         spin_unlock(&res->spinlock);
2320                         goto leave;
2321                 }
2322                 /* TODO: if node died: stop, clean up, return error */
2323         }
2324
2325         /* all done, set the owner, clear the flag */
2326         spin_lock(&res->spinlock);
2327         dlm_set_lockres_owner(dlm, res, target);
2328         res->state &= ~DLM_LOCK_RES_MIGRATING;
2329         dlm_remove_nonlocal_locks(dlm, res);
2330         spin_unlock(&res->spinlock);
2331         wake_up(&res->wq);
2332
2333         /* master is known, detach if not already detached */
2334         dlm_mle_detach_hb_events(dlm, mle);
2335         dlm_put_mle_inuse(mle);
2336         ret = 0;
2337
2338         dlm_lockres_calc_usage(dlm, res);
2339
2340 leave:
2341         /* re-dirty the lockres if we failed */
2342         if (ret < 0)
2343                 dlm_kick_thread(dlm, res);
2344
2345         /* TODO: cleanup */
2346         if (mres)
2347                 free_page((unsigned long)mres);
2348
2349         dlm_put(dlm);
2350
2351         mlog(0, "returning %d\n", ret);
2352         return ret;
2353 }
2354 EXPORT_SYMBOL_GPL(dlm_migrate_lockres);
2355
2356 int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock)
2357 {
2358         int ret;
2359         spin_lock(&dlm->ast_lock);
2360         spin_lock(&lock->spinlock);
2361         ret = (list_empty(&lock->bast_list) && !lock->bast_pending);
2362         spin_unlock(&lock->spinlock);
2363         spin_unlock(&dlm->ast_lock);
2364         return ret;
2365 }
2366
2367 static int dlm_migration_can_proceed(struct dlm_ctxt *dlm,
2368                                      struct dlm_lock_resource *res,
2369                                      u8 mig_target)
2370 {
2371         int can_proceed;
2372         spin_lock(&res->spinlock);
2373         can_proceed = !!(res->state & DLM_LOCK_RES_MIGRATING);
2374         spin_unlock(&res->spinlock);
2375
2376         /* target has died, so make the caller break out of the
2377          * wait_event, but caller must recheck the domain_map */
2378         spin_lock(&dlm->spinlock);
2379         if (!test_bit(mig_target, dlm->domain_map))
2380                 can_proceed = 1;
2381         spin_unlock(&dlm->spinlock);
2382         return can_proceed;
2383 }
2384
2385 int dlm_lockres_is_dirty(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
2386 {
2387         int ret;
2388         spin_lock(&res->spinlock);
2389         ret = !!(res->state & DLM_LOCK_RES_DIRTY);
2390         spin_unlock(&res->spinlock);
2391         return ret;
2392 }
2393
2394
2395 static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
2396                                        struct dlm_lock_resource *res,
2397                                        u8 target)
2398 {
2399         int ret = 0;
2400
2401         mlog(0, "dlm_mark_lockres_migrating: %.*s, from %u to %u\n",
2402                res->lockname.len, res->lockname.name, dlm->node_num,
2403                target);
2404         /* need to set MIGRATING flag on lockres.  this is done by
2405          * ensuring that all asts have been flushed for this lockres. */
2406         spin_lock(&res->spinlock);
2407         BUG_ON(res->migration_pending);
2408         res->migration_pending = 1;
2409         /* strategy is to reserve an extra ast then release
2410          * it below, letting the release do all of the work */
2411         __dlm_lockres_reserve_ast(res);
2412         spin_unlock(&res->spinlock);
2413
2414         /* now flush all the pending asts.. hang out for a bit */
2415         dlm_kick_thread(dlm, res);
2416         wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
2417         dlm_lockres_release_ast(dlm, res);
2418
2419         mlog(0, "about to wait on migration_wq, dirty=%s\n",
2420                res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
2421         /* if the extra ref we just put was the final one, this
2422          * will pass thru immediately.  otherwise, we need to wait
2423          * for the last ast to finish. */
2424 again:
2425         ret = wait_event_interruptible_timeout(dlm->migration_wq,
2426                    dlm_migration_can_proceed(dlm, res, target),
2427                    msecs_to_jiffies(1000));
2428         if (ret < 0) {
2429                 mlog(0, "woken again: migrating? %s, dead? %s\n",
2430                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2431                        test_bit(target, dlm->domain_map) ? "no":"yes");
2432         } else {
2433                 mlog(0, "all is well: migrating? %s, dead? %s\n",
2434                        res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
2435                        test_bit(target, dlm->domain_map) ? "no":"yes");
2436         }
2437         if (!dlm_migration_can_proceed(dlm, res, target)) {
2438                 mlog(0, "trying again...\n");
2439                 goto again;
2440         }
2441
2442         /* did the target go down or die? */
2443         spin_lock(&dlm->spinlock);
2444         if (!test_bit(target, dlm->domain_map)) {
2445                 mlog(ML_ERROR, "aha. migration target %u just went down\n",
2446                      target);
2447                 ret = -EHOSTDOWN;
2448         }
2449         spin_unlock(&dlm->spinlock);
2450
2451         /*
2452          * at this point:
2453          *
2454          *   o the DLM_LOCK_RES_MIGRATING flag is set
2455          *   o there are no pending asts on this lockres
2456          *   o all processes trying to reserve an ast on this
2457          *     lockres must wait for the MIGRATING flag to clear
2458          */
2459         return ret;
2460 }
2461
2462 /* last step in the migration process.
2463  * original master calls this to free all of the dlm_lock
2464  * structures that used to be for other nodes. */
2465 static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
2466                                       struct dlm_lock_resource *res)
2467 {
2468         struct list_head *iter, *iter2;
2469         struct list_head *queue = &res->granted;
2470         int i;
2471         struct dlm_lock *lock;
2472
2473         assert_spin_locked(&res->spinlock);
2474
2475         BUG_ON(res->owner == dlm->node_num);
2476
2477         for (i=0; i<3; i++) {
2478                 list_for_each_safe(iter, iter2, queue) {
2479                         lock = list_entry (iter, struct dlm_lock, list);
2480                         if (lock->ml.node != dlm->node_num) {
2481                                 mlog(0, "putting lock for node %u\n",
2482                                      lock->ml.node);
2483                                 /* be extra careful */
2484                                 BUG_ON(!list_empty(&lock->ast_list));
2485                                 BUG_ON(!list_empty(&lock->bast_list));
2486                                 BUG_ON(lock->ast_pending);
2487                                 BUG_ON(lock->bast_pending);
2488                                 list_del_init(&lock->list);
2489                                 dlm_lock_put(lock);
2490                         }
2491                 }
2492                 queue++;
2493         }
2494 }
2495
2496 /* for now this is not too intelligent.  we will
2497  * need stats to make this do the right thing.
2498  * this just finds the first lock on one of the
2499  * queues and uses that node as the target. */
2500 static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
2501                                     struct dlm_lock_resource *res)
2502 {
2503         int i;
2504         struct list_head *queue = &res->granted;
2505         struct list_head *iter;
2506         struct dlm_lock *lock;
2507         int nodenum;
2508
2509         assert_spin_locked(&dlm->spinlock);
2510
2511         spin_lock(&res->spinlock);
2512         for (i=0; i<3; i++) {
2513                 list_for_each(iter, queue) {
2514                         /* up to the caller to make sure this node
2515                          * is alive */
2516                         lock = list_entry (iter, struct dlm_lock, list);
2517                         if (lock->ml.node != dlm->node_num) {
2518                                 spin_unlock(&res->spinlock);
2519                                 return lock->ml.node;
2520                         }
2521                 }
2522                 queue++;
2523         }
2524         spin_unlock(&res->spinlock);
2525         mlog(0, "have not found a suitable target yet! checking domain map\n");
2526
2527         /* ok now we're getting desperate.  pick anyone alive. */
2528         nodenum = -1;
2529         while (1) {
2530                 nodenum = find_next_bit(dlm->domain_map,
2531                                         O2NM_MAX_NODES, nodenum+1);
2532                 mlog(0, "found %d in domain map\n", nodenum);
2533                 if (nodenum >= O2NM_MAX_NODES)
2534                         break;
2535                 if (nodenum != dlm->node_num) {
2536                         mlog(0, "picking %d\n", nodenum);
2537                         return nodenum;
2538                 }
2539         }
2540
2541         mlog(0, "giving up.  no master to migrate to\n");
2542         return DLM_LOCK_RES_OWNER_UNKNOWN;
2543 }
2544
2545
2546
2547 /* this is called by the new master once all lockres
2548  * data has been received */
2549 static int dlm_do_migrate_request(struct dlm_ctxt *dlm,
2550                                   struct dlm_lock_resource *res,
2551                                   u8 master, u8 new_master,
2552                                   struct dlm_node_iter *iter)
2553 {
2554         struct dlm_migrate_request migrate;
2555         int ret, status = 0;
2556         int nodenum;
2557
2558         memset(&migrate, 0, sizeof(migrate));
2559         migrate.namelen = res->lockname.len;
2560         memcpy(migrate.name, res->lockname.name, migrate.namelen);
2561         migrate.new_master = new_master;
2562         migrate.master = master;
2563
2564         ret = 0;
2565
2566         /* send message to all nodes, except the master and myself */
2567         while ((nodenum = dlm_node_iter_next(iter)) >= 0) {
2568                 if (nodenum == master ||
2569                     nodenum == new_master)
2570                         continue;
2571
2572                 ret = o2net_send_message(DLM_MIGRATE_REQUEST_MSG, dlm->key,
2573                                          &migrate, sizeof(migrate), nodenum,
2574                                          &status);
2575                 if (ret < 0)
2576                         mlog_errno(ret);
2577                 else if (status < 0) {
2578                         mlog(0, "migrate request (node %u) returned %d!\n",
2579                              nodenum, status);
2580                         ret = status;
2581                 }
2582         }
2583
2584         if (ret < 0)
2585                 mlog_errno(ret);
2586
2587         mlog(0, "returning ret=%d\n", ret);
2588         return ret;
2589 }
2590
2591
2592 /* if there is an existing mle for this lockres, we now know who the master is.
2593  * (the one who sent us *this* message) we can clear it up right away.
2594  * since the process that put the mle on the list still has a reference to it,
2595  * we can unhash it now, set the master and wake the process.  as a result,
2596  * we will have no mle in the list to start with.  now we can add an mle for
2597  * the migration and this should be the only one found for those scanning the
2598  * list.  */
2599 int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data)
2600 {
2601         struct dlm_ctxt *dlm = data;
2602         struct dlm_lock_resource *res = NULL;
2603         struct dlm_migrate_request *migrate = (struct dlm_migrate_request *) msg->buf;
2604         struct dlm_master_list_entry *mle = NULL, *oldmle = NULL;
2605         const char *name;
2606         unsigned int namelen, hash;
2607         int ret = 0;
2608
2609         if (!dlm_grab(dlm))
2610                 return -EINVAL;
2611
2612         name = migrate->name;
2613         namelen = migrate->namelen;
2614         hash = dlm_lockid_hash(name, namelen);
2615
2616         /* preallocate.. if this fails, abort */
2617         mle = (struct dlm_master_list_entry *) kmem_cache_alloc(dlm_mle_cache,
2618                                                          GFP_KERNEL);
2619
2620         if (!mle) {
2621                 ret = -ENOMEM;
2622                 goto leave;
2623         }
2624
2625         /* check for pre-existing lock */
2626         spin_lock(&dlm->spinlock);
2627         res = __dlm_lookup_lockres(dlm, name, namelen, hash);
2628         spin_lock(&dlm->master_lock);
2629
2630         if (res) {
2631                 spin_lock(&res->spinlock);
2632                 if (res->state & DLM_LOCK_RES_RECOVERING) {
2633                         /* if all is working ok, this can only mean that we got
2634                         * a migrate request from a node that we now see as
2635                         * dead.  what can we do here?  drop it to the floor? */
2636                         spin_unlock(&res->spinlock);
2637                         mlog(ML_ERROR, "Got a migrate request, but the "
2638                              "lockres is marked as recovering!");
2639                         kmem_cache_free(dlm_mle_cache, mle);
2640                         ret = -EINVAL; /* need a better solution */
2641                         goto unlock;
2642                 }
2643                 res->state |= DLM_LOCK_RES_MIGRATING;
2644                 spin_unlock(&res->spinlock);
2645         }
2646
2647         /* ignore status.  only nonzero status would BUG. */
2648         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
2649                                     name, namelen,
2650                                     migrate->new_master,
2651                                     migrate->master);
2652
2653 unlock:
2654         spin_unlock(&dlm->master_lock);
2655         spin_unlock(&dlm->spinlock);
2656
2657         if (oldmle) {
2658                 /* master is known, detach if not already detached */
2659                 dlm_mle_detach_hb_events(dlm, oldmle);
2660                 dlm_put_mle(oldmle);
2661         }
2662
2663         if (res)
2664                 dlm_lockres_put(res);
2665 leave:
2666         dlm_put(dlm);
2667         return ret;
2668 }
2669
2670 /* must be holding dlm->spinlock and dlm->master_lock
2671  * when adding a migration mle, we can clear any other mles
2672  * in the master list because we know with certainty that
2673  * the master is "master".  so we remove any old mle from
2674  * the list after setting it's master field, and then add
2675  * the new migration mle.  this way we can hold with the rule
2676  * of having only one mle for a given lock name at all times. */
2677 static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
2678                                  struct dlm_lock_resource *res,
2679                                  struct dlm_master_list_entry *mle,
2680                                  struct dlm_master_list_entry **oldmle,
2681                                  const char *name, unsigned int namelen,
2682                                  u8 new_master, u8 master)
2683 {
2684         int found;
2685         int ret = 0;
2686
2687         *oldmle = NULL;
2688
2689         mlog_entry_void();
2690
2691         assert_spin_locked(&dlm->spinlock);
2692         assert_spin_locked(&dlm->master_lock);
2693
2694         /* caller is responsible for any ref taken here on oldmle */
2695         found = dlm_find_mle(dlm, oldmle, (char *)name, namelen);
2696         if (found) {
2697                 struct dlm_master_list_entry *tmp = *oldmle;
2698                 spin_lock(&tmp->spinlock);
2699                 if (tmp->type == DLM_MLE_MIGRATION) {
2700                         if (master == dlm->node_num) {
2701                                 /* ah another process raced me to it */
2702                                 mlog(0, "tried to migrate %.*s, but some "
2703                                      "process beat me to it\n",
2704                                      namelen, name);
2705                                 ret = -EEXIST;
2706                         } else {
2707                                 /* bad.  2 NODES are trying to migrate! */
2708                                 mlog(ML_ERROR, "migration error  mle: "
2709                                      "master=%u new_master=%u // request: "
2710                                      "master=%u new_master=%u // "
2711                                      "lockres=%.*s\n",
2712                                      tmp->master, tmp->new_master,
2713                                      master, new_master,
2714                                      namelen, name);
2715                                 BUG();
2716                         }
2717                 } else {
2718                         /* this is essentially what assert_master does */
2719                         tmp->master = master;
2720                         atomic_set(&tmp->woken, 1);
2721                         wake_up(&tmp->wq);
2722                         /* remove it from the list so that only one
2723                          * mle will be found */
2724                         list_del_init(&tmp->list);
2725                         __dlm_mle_detach_hb_events(dlm, mle);
2726                 }
2727                 spin_unlock(&tmp->spinlock);
2728         }
2729
2730         /* now add a migration mle to the tail of the list */
2731         dlm_init_mle(mle, DLM_MLE_MIGRATION, dlm, res, name, namelen);
2732         mle->new_master = new_master;
2733         mle->master = master;
2734         /* do this for consistency with other mle types */
2735         set_bit(new_master, mle->maybe_map);
2736         list_add(&mle->list, &dlm->master_list);
2737
2738         return ret;
2739 }
2740
2741
2742 void dlm_clean_master_list(struct dlm_ctxt *dlm, u8 dead_node)
2743 {
2744         struct list_head *iter, *iter2;
2745         struct dlm_master_list_entry *mle;
2746         struct dlm_lock_resource *res;
2747         unsigned int hash;
2748
2749         mlog_entry("dlm=%s, dead node=%u\n", dlm->name, dead_node);
2750 top:
2751         assert_spin_locked(&dlm->spinlock);
2752
2753         /* clean the master list */
2754         spin_lock(&dlm->master_lock);
2755         list_for_each_safe(iter, iter2, &dlm->master_list) {
2756                 mle = list_entry(iter, struct dlm_master_list_entry, list);
2757
2758                 BUG_ON(mle->type != DLM_MLE_BLOCK &&
2759                        mle->type != DLM_MLE_MASTER &&
2760                        mle->type != DLM_MLE_MIGRATION);
2761
2762                 /* MASTER mles are initiated locally.  the waiting
2763                  * process will notice the node map change
2764                  * shortly.  let that happen as normal. */
2765                 if (mle->type == DLM_MLE_MASTER)
2766                         continue;
2767
2768
2769                 /* BLOCK mles are initiated by other nodes.
2770                  * need to clean up if the dead node would have
2771                  * been the master. */
2772                 if (mle->type == DLM_MLE_BLOCK) {
2773                         int bit;
2774
2775                         spin_lock(&mle->spinlock);
2776                         bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
2777                         if (bit != dead_node) {
2778                                 mlog(0, "mle found, but dead node %u would "
2779                                      "not have been master\n", dead_node);
2780                                 spin_unlock(&mle->spinlock);
2781                         } else {
2782                                 /* must drop the refcount by one since the
2783                                  * assert_master will never arrive.  this
2784                                  * may result in the mle being unlinked and
2785                                  * freed, but there may still be a process
2786                                  * waiting in the dlmlock path which is fine. */
2787                                 mlog(ML_ERROR, "node %u was expected master\n",
2788                                      dead_node);
2789                                 atomic_set(&mle->woken, 1);
2790                                 spin_unlock(&mle->spinlock);
2791                                 wake_up(&mle->wq);
2792                                 /* do not need events any longer, so detach
2793                                  * from heartbeat */
2794                                 __dlm_mle_detach_hb_events(dlm, mle);
2795                                 __dlm_put_mle(mle);
2796                         }
2797                         continue;
2798                 }
2799
2800                 /* everything else is a MIGRATION mle */
2801
2802                 /* the rule for MIGRATION mles is that the master
2803                  * becomes UNKNOWN if *either* the original or
2804                  * the new master dies.  all UNKNOWN lockreses
2805                  * are sent to whichever node becomes the recovery
2806                  * master.  the new master is responsible for
2807                  * determining if there is still a master for
2808                  * this lockres, or if he needs to take over
2809                  * mastery.  either way, this node should expect
2810                  * another message to resolve this. */
2811                 if (mle->master != dead_node &&
2812                     mle->new_master != dead_node)
2813                         continue;
2814
2815                 /* if we have reached this point, this mle needs to
2816                  * be removed from the list and freed. */
2817
2818                 /* remove from the list early.  NOTE: unlinking
2819                  * list_head while in list_for_each_safe */
2820                 __dlm_mle_detach_hb_events(dlm, mle);
2821                 spin_lock(&mle->spinlock);
2822                 list_del_init(&mle->list);
2823                 atomic_set(&mle->woken, 1);
2824                 spin_unlock(&mle->spinlock);
2825                 wake_up(&mle->wq);
2826
2827                 mlog(0, "%s: node %u died during migration from "
2828                      "%u to %u!\n", dlm->name, dead_node,
2829                      mle->master, mle->new_master);
2830                 /* if there is a lockres associated with this
2831                  * mle, find it and set its owner to UNKNOWN */
2832                 hash = dlm_lockid_hash(mle->u.name.name, mle->u.name.len);
2833                 res = __dlm_lookup_lockres(dlm, mle->u.name.name,
2834                                            mle->u.name.len, hash);
2835                 if (res) {
2836                         /* unfortunately if we hit this rare case, our
2837                          * lock ordering is messed.  we need to drop
2838                          * the master lock so that we can take the
2839                          * lockres lock, meaning that we will have to
2840                          * restart from the head of list. */
2841                         spin_unlock(&dlm->master_lock);
2842
2843                         /* move lockres onto recovery list */
2844                         spin_lock(&res->spinlock);
2845                         dlm_set_lockres_owner(dlm, res,
2846                                         DLM_LOCK_RES_OWNER_UNKNOWN);
2847                         dlm_move_lockres_to_recovery_list(dlm, res);
2848                         spin_unlock(&res->spinlock);
2849                         dlm_lockres_put(res);
2850
2851                         /* about to get rid of mle, detach from heartbeat */
2852                         __dlm_mle_detach_hb_events(dlm, mle);
2853
2854                         /* dump the mle */
2855                         spin_lock(&dlm->master_lock);
2856                         __dlm_put_mle(mle);
2857                         spin_unlock(&dlm->master_lock);
2858
2859                         /* restart */
2860                         goto top;
2861                 }
2862
2863                 /* this may be the last reference */
2864                 __dlm_put_mle(mle);
2865         }
2866         spin_unlock(&dlm->master_lock);
2867 }
2868
2869
2870 int dlm_finish_migration(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
2871                          u8 old_master)
2872 {
2873         struct dlm_node_iter iter;
2874         int ret = 0;
2875
2876         spin_lock(&dlm->spinlock);
2877         dlm_node_iter_init(dlm->domain_map, &iter);
2878         clear_bit(old_master, iter.node_map);
2879         clear_bit(dlm->node_num, iter.node_map);
2880         spin_unlock(&dlm->spinlock);
2881
2882         mlog(0, "now time to do a migrate request to other nodes\n");
2883         ret = dlm_do_migrate_request(dlm, res, old_master,
2884                                      dlm->node_num, &iter);
2885         if (ret < 0) {
2886                 mlog_errno(ret);
2887                 goto leave;
2888         }
2889
2890         mlog(0, "doing assert master of %.*s to all except the original node\n",
2891              res->lockname.len, res->lockname.name);
2892         /* this call now finishes out the nodemap
2893          * even if one or more nodes die */
2894         ret = dlm_do_assert_master(dlm, res->lockname.name,
2895                                    res->lockname.len, iter.node_map,
2896                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
2897         if (ret < 0) {
2898                 /* no longer need to retry.  all living nodes contacted. */
2899                 mlog_errno(ret);
2900                 ret = 0;
2901         }
2902
2903         memset(iter.node_map, 0, sizeof(iter.node_map));
2904         set_bit(old_master, iter.node_map);
2905         mlog(0, "doing assert master of %.*s back to %u\n",
2906              res->lockname.len, res->lockname.name, old_master);
2907         ret = dlm_do_assert_master(dlm, res->lockname.name,
2908                                    res->lockname.len, iter.node_map,
2909                                    DLM_ASSERT_MASTER_FINISH_MIGRATION);
2910         if (ret < 0) {
2911                 mlog(0, "assert master to original master failed "
2912                      "with %d.\n", ret);
2913                 /* the only nonzero status here would be because of
2914                  * a dead original node.  we're done. */
2915                 ret = 0;
2916         }
2917
2918         /* all done, set the owner, clear the flag */
2919         spin_lock(&res->spinlock);
2920         dlm_set_lockres_owner(dlm, res, dlm->node_num);
2921         res->state &= ~DLM_LOCK_RES_MIGRATING;
2922         spin_unlock(&res->spinlock);
2923         /* re-dirty it on the new master */
2924         dlm_kick_thread(dlm, res);
2925         wake_up(&res->wq);
2926 leave:
2927         return ret;
2928 }
2929
2930 /*
2931  * LOCKRES AST REFCOUNT
2932  * this is integral to migration
2933  */
2934
2935 /* for future intent to call an ast, reserve one ahead of time.
2936  * this should be called only after waiting on the lockres
2937  * with dlm_wait_on_lockres, and while still holding the
2938  * spinlock after the call. */
2939 void __dlm_lockres_reserve_ast(struct dlm_lock_resource *res)
2940 {
2941         assert_spin_locked(&res->spinlock);
2942         if (res->state & DLM_LOCK_RES_MIGRATING) {
2943                 __dlm_print_one_lock_resource(res);
2944         }
2945         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
2946
2947         atomic_inc(&res->asts_reserved);
2948 }
2949
2950 /*
2951  * used to drop the reserved ast, either because it went unused,
2952  * or because the ast/bast was actually called.
2953  *
2954  * also, if there is a pending migration on this lockres,
2955  * and this was the last pending ast on the lockres,
2956  * atomically set the MIGRATING flag before we drop the lock.
2957  * this is how we ensure that migration can proceed with no
2958  * asts in progress.  note that it is ok if the state of the
2959  * queues is such that a lock should be granted in the future
2960  * or that a bast should be fired, because the new master will
2961  * shuffle the lists on this lockres as soon as it is migrated.
2962  */
2963 void dlm_lockres_release_ast(struct dlm_ctxt *dlm,
2964                              struct dlm_lock_resource *res)
2965 {
2966         if (!atomic_dec_and_lock(&res->asts_reserved, &res->spinlock))
2967                 return;
2968
2969         if (!res->migration_pending) {
2970                 spin_unlock(&res->spinlock);
2971                 return;
2972         }
2973
2974         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
2975         res->migration_pending = 0;
2976         res->state |= DLM_LOCK_RES_MIGRATING;
2977         spin_unlock(&res->spinlock);
2978         wake_up(&res->wq);
2979         wake_up(&dlm->migration_wq);
2980 }