fs/ocfs2/dlm/dlmthread.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * dlmthread.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/highmem.h>
  32 #include <linux/init.h>
  33 #include <linux/sysctl.h>
  34 #include <linux/random.h>
  35 #include <linux/blkdev.h>
  36 #include <linux/socket.h>
  37 #include <linux/inet.h>
  38 #include <linux/timer.h>
  39 #include <linux/kthread.h>
  40 #include <linux/delay.h>
  41
  42
  43 #include "cluster/heartbeat.h"
  44 #include "cluster/nodemanager.h"
  45 #include "cluster/tcp.h"
  46
  47 #include "dlmapi.h"
  48 #include "dlmcommon.h"
  49 #include "dlmdomain.h"
  50
  51 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_THREAD)
  52 #include "cluster/masklog.h"
  53
  54 static int dlm_thread(void *data);
  55 static void dlm_flush_asts(struct dlm_ctxt *dlm);
  56
  57 #define dlm_lock_is_remote(dlm, lock)     ((lock)->ml.node != (dlm)->node_num)
  58
  59 /* will exit holding res->spinlock, but may drop in function */
  60 /* waits until flags are cleared on res->state */
  61 void __dlm_wait_on_lockres_flags(struct dlm_lock_resource *res, int flags)
  62 {
  63         DECLARE_WAITQUEUE(wait, current);
  64
  65         assert_spin_locked(&res->spinlock);
  66
  67         add_wait_queue(&res->wq, &wait);
  68 repeat:
  69         set_current_state(TASK_UNINTERRUPTIBLE);
  70         if (res->state & flags) {
  71                 spin_unlock(&res->spinlock);
  72                 schedule();
  73                 spin_lock(&res->spinlock);
  74                 goto repeat;
  75         }
  76         remove_wait_queue(&res->wq, &wait);
  77         __set_current_state(TASK_RUNNING);
  78 }
  79
  80 int __dlm_lockres_has_locks(struct dlm_lock_resource *res)
  81 {
  82         if (list_empty(&res->granted) &&
  83             list_empty(&res->converting) &&
  84             list_empty(&res->blocked))
  85                 return 0;
  86         return 1;
  87 }
  88
  89 /* "unused": the lockres has no locks, is not on the dirty list,
  90  * has no inflight locks (in the gap between mastery and acquiring
  91  * the first lock), and has no bits in its refmap.
  92  * truly ready to be freed. */
  93 int __dlm_lockres_unused(struct dlm_lock_resource *res)
  94 {
  95         int bit;
  96
  97         assert_spin_locked(&res->spinlock);
  98
  99         if (__dlm_lockres_has_locks(res))
 100                 return 0;
 101
 102         /* Locks are in the process of being created */
 103         if (res->inflight_locks)
 104                 return 0;
 105
 106         if (!list_empty(&res->dirty) || res->state & DLM_LOCK_RES_DIRTY)
 107                 return 0;
 108
 109         if (res->state & DLM_LOCK_RES_RECOVERING)
 110                 return 0;
 111
 112         /* Another node has this resource with this node as the master */
 113         bit = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
 114         if (bit < O2NM_MAX_NODES)
 115                 return 0;
 116
 117         return 1;
 118 }
 119
 120
 121 /* Call whenever you may have added or deleted something from one of
 122  * the lockres queue's. This will figure out whether it belongs on the
 123  * unused list or not and does the appropriate thing. */
 124 void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
 125                               struct dlm_lock_resource *res)
 126 {
 127         assert_spin_locked(&dlm->spinlock);
 128         assert_spin_locked(&res->spinlock);
 129
 130         if (__dlm_lockres_unused(res)){
 131                 if (list_empty(&res->purge)) {
 132                         mlog(0, "%s: Adding res %.*s to purge list\n",
 133                              dlm->name, res->lockname.len, res->lockname.name);
 134
 135                         res->last_used = jiffies;
 136                         dlm_lockres_get(res);
 137                         list_add_tail(&res->purge, &dlm->purge_list);
 138                         dlm->purge_count++;
 139                 }
 140         } else if (!list_empty(&res->purge)) {
 141                 mlog(0, "%s: Removing res %.*s from purge list\n",
 142                      dlm->name, res->lockname.len, res->lockname.name);
 143
 144                 list_del_init(&res->purge);
 145                 dlm_lockres_put(res);
 146                 dlm->purge_count--;
 147         }
 148 }
 149
 150 void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
 151                             struct dlm_lock_resource *res)
 152 {
 153         spin_lock(&dlm->spinlock);
 154         spin_lock(&res->spinlock);
 155
 156         __dlm_lockres_calc_usage(dlm, res);
 157
 158         spin_unlock(&res->spinlock);
 159         spin_unlock(&dlm->spinlock);
 160 }
 161
 162 static void dlm_purge_lockres(struct dlm_ctxt *dlm,
 163                              struct dlm_lock_resource *res)
 164 {
 165         int master;
 166         int ret = 0;
 167
 168         assert_spin_locked(&dlm->spinlock);
 169         assert_spin_locked(&res->spinlock);
 170
 171         master = (res->owner == dlm->node_num);
 172
 173         mlog(0, "%s: Purging res %.*s, master %d\n", dlm->name,
 174              res->lockname.len, res->lockname.name, master);
 175
 176         if (!master) {
 177                 res->state |= DLM_LOCK_RES_DROPPING_REF;
 178                 /* drop spinlock...  retake below */
 179                 spin_unlock(&res->spinlock);
 180                 spin_unlock(&dlm->spinlock);
 181
 182                 spin_lock(&res->spinlock);
 183                 /* This ensures that clear refmap is sent after the set */
 184                 __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
 185                 spin_unlock(&res->spinlock);
 186
 187                 /* clear our bit from the master's refmap, ignore errors */
 188                 ret = dlm_drop_lockres_ref(dlm, res);
 189                 if (ret < 0) {
 190                         if (!dlm_is_host_down(ret))
 191                                 BUG();
 192                 }
 193                 spin_lock(&dlm->spinlock);
 194                 spin_lock(&res->spinlock);
 195         }
 196
 197         if (!list_empty(&res->purge)) {
 198                 mlog(0, "%s: Removing res %.*s from purgelist, master %d\n",
 199                      dlm->name, res->lockname.len, res->lockname.name, master);
 200                 list_del_init(&res->purge);
 201                 dlm_lockres_put(res);
 202                 dlm->purge_count--;
 203         }
 204
 205         if (!__dlm_lockres_unused(res)) {
 206                 mlog(ML_ERROR, "%s: res %.*s in use after deref\n",
 207                      dlm->name, res->lockname.len, res->lockname.name);
 208                 __dlm_print_one_lock_resource(res);
 209                 BUG();
 210         }
 211
 212         __dlm_unhash_lockres(dlm, res);
 213
 214         /* lockres is not in the hash now.  drop the flag and wake up
 215          * any processes waiting in dlm_get_lock_resource. */
 216         if (!master) {
 217                 res->state &= ~DLM_LOCK_RES_DROPPING_REF;
 218                 spin_unlock(&res->spinlock);
 219                 wake_up(&res->wq);
 220         } else
 221                 spin_unlock(&res->spinlock);
 222 }
 223
 224 static void dlm_run_purge_list(struct dlm_ctxt *dlm,
 225                                int purge_now)
 226 {
 227         unsigned int run_max, unused;
 228         unsigned long purge_jiffies;
 229         struct dlm_lock_resource *lockres;
 230
 231         spin_lock(&dlm->spinlock);
 232         run_max = dlm->purge_count;
 233
 234         while(run_max && !list_empty(&dlm->purge_list)) {
 235                 run_max--;
 236
 237                 lockres = list_entry(dlm->purge_list.next,
 238                                      struct dlm_lock_resource, purge);
 239
 240                 spin_lock(&lockres->spinlock);
 241
 242                 purge_jiffies = lockres->last_used +
 243                         msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
 244
 245                 /* Make sure that we want to be processing this guy at
 246                  * this time. */
 247                 if (!purge_now && time_after(purge_jiffies, jiffies)) {
 248                         /* Since resources are added to the purge list
 249                          * in tail order, we can stop at the first
 250                          * unpurgable resource -- anyone added after
 251                          * him will have a greater last_used value */
 252                         spin_unlock(&lockres->spinlock);
 253                         break;
 254                 }
 255
 256                 /* Status of the lockres *might* change so double
 257                  * check. If the lockres is unused, holding the dlm
 258                  * spinlock will prevent people from getting and more
 259                  * refs on it. */
 260                 unused = __dlm_lockres_unused(lockres);
 261                 if (!unused ||
 262                     (lockres->state & DLM_LOCK_RES_MIGRATING)) {
 263                         mlog(0, "%s: res %.*s is in use or being remastered, "
 264                              "used %d, state %d\n", dlm->name,
 265                              lockres->lockname.len, lockres->lockname.name,
 266                              !unused, lockres->state);
 267                         list_move_tail(&dlm->purge_list, &lockres->purge);
 268                         spin_unlock(&lockres->spinlock);
 269                         continue;
 270                 }
 271
 272                 dlm_lockres_get(lockres);
 273
 274                 dlm_purge_lockres(dlm, lockres);
 275
 276                 dlm_lockres_put(lockres);
 277
 278                 /* Avoid adding any scheduling latencies */
 279                 cond_resched_lock(&dlm->spinlock);
 280         }
 281
 282         spin_unlock(&dlm->spinlock);
 283 }
 284
 285 static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
 286                               struct dlm_lock_resource *res)
 287 {
 288         struct dlm_lock *lock, *target;
 289         int can_grant = 1;
 290
 291         /*
 292          * Because this function is called with the lockres
 293          * spinlock, and because we know that it is not migrating/
 294          * recovering/in-progress, it is fine to reserve asts and
 295          * basts right before queueing them all throughout
 296          */
 297         assert_spin_locked(&dlm->ast_lock);
 298         assert_spin_locked(&res->spinlock);
 299         BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
 300                               DLM_LOCK_RES_RECOVERING|
 301                               DLM_LOCK_RES_IN_PROGRESS)));
 302
 303 converting:
 304         if (list_empty(&res->converting))
 305                 goto blocked;
 306         mlog(0, "%s: res %.*s has locks on the convert queue\n", dlm->name,
 307              res->lockname.len, res->lockname.name);
 308
 309         target = list_entry(res->converting.next, struct dlm_lock, list);
 310         if (target->ml.convert_type == LKM_IVMODE) {
 311                 mlog(ML_ERROR, "%s: res %.*s converting lock to invalid mode\n",
 312                      dlm->name, res->lockname.len, res->lockname.name);
 313                 BUG();
 314         }
 315         list_for_each_entry(lock, &res->granted, list) {
 316                 if (lock==target)
 317                         continue;
 318                 if (!dlm_lock_compatible(lock->ml.type,
 319                                          target->ml.convert_type)) {
 320                         can_grant = 0;
 321                         /* queue the BAST if not already */
 322                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 323                                 __dlm_lockres_reserve_ast(res);
 324                                 __dlm_queue_bast(dlm, lock);
 325                         }
 326                         /* update the highest_blocked if needed */
 327                         if (lock->ml.highest_blocked < target->ml.convert_type)
 328                                 lock->ml.highest_blocked =
 329                                         target->ml.convert_type;
 330                 }
 331         }
 332
 333         list_for_each_entry(lock, &res->converting, list) {
 334                 if (lock==target)
 335                         continue;
 336                 if (!dlm_lock_compatible(lock->ml.type,
 337                                          target->ml.convert_type)) {
 338                         can_grant = 0;
 339                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 340                                 __dlm_lockres_reserve_ast(res);
 341                                 __dlm_queue_bast(dlm, lock);
 342                         }
 343                         if (lock->ml.highest_blocked < target->ml.convert_type)
 344                                 lock->ml.highest_blocked =
 345                                         target->ml.convert_type;
 346                 }
 347         }
 348
 349         /* we can convert the lock */
 350         if (can_grant) {
 351                 spin_lock(&target->spinlock);
 352                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 353
 354                 mlog(0, "%s: res %.*s, AST for Converting lock %u:%llu, type "
 355                      "%d => %d, node %u\n", dlm->name, res->lockname.len,
 356                      res->lockname.name,
 357                      dlm_get_lock_cookie_node(be64_to_cpu(target->ml.cookie)),
 358                      dlm_get_lock_cookie_seq(be64_to_cpu(target->ml.cookie)),
 359                      target->ml.type,
 360                      target->ml.convert_type, target->ml.node);
 361
 362                 target->ml.type = target->ml.convert_type;
 363                 target->ml.convert_type = LKM_IVMODE;
 364                 list_move_tail(&target->list, &res->granted);
 365
 366                 BUG_ON(!target->lksb);
 367                 target->lksb->status = DLM_NORMAL;
 368
 369                 spin_unlock(&target->spinlock);
 370
 371                 __dlm_lockres_reserve_ast(res);
 372                 __dlm_queue_ast(dlm, target);
 373                 /* go back and check for more */
 374                 goto converting;
 375         }
 376
 377 blocked:
 378         if (list_empty(&res->blocked))
 379                 goto leave;
 380         target = list_entry(res->blocked.next, struct dlm_lock, list);
 381
 382         list_for_each_entry(lock, &res->granted, list) {
 383                 if (lock==target)
 384                         continue;
 385                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 386                         can_grant = 0;
 387                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 388                                 __dlm_lockres_reserve_ast(res);
 389                                 __dlm_queue_bast(dlm, lock);
 390                         }
 391                         if (lock->ml.highest_blocked < target->ml.type)
 392                                 lock->ml.highest_blocked = target->ml.type;
 393                 }
 394         }
 395
 396         list_for_each_entry(lock, &res->converting, list) {
 397                 if (lock==target)
 398                         continue;
 399                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 400                         can_grant = 0;
 401                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 402                                 __dlm_lockres_reserve_ast(res);
 403                                 __dlm_queue_bast(dlm, lock);
 404                         }
 405                         if (lock->ml.highest_blocked < target->ml.type)
 406                                 lock->ml.highest_blocked = target->ml.type;
 407                 }
 408         }
 409
 410         /* we can grant the blocked lock (only
 411          * possible if converting list empty) */
 412         if (can_grant) {
 413                 spin_lock(&target->spinlock);
 414                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 415
 416                 mlog(0, "%s: res %.*s, AST for Blocked lock %u:%llu, type %d, "
 417                      "node %u\n", dlm->name, res->lockname.len,
 418                      res->lockname.name,
 419                      dlm_get_lock_cookie_node(be64_to_cpu(target->ml.cookie)),
 420                      dlm_get_lock_cookie_seq(be64_to_cpu(target->ml.cookie)),
 421                      target->ml.type, target->ml.node);
 422
 423                 /* target->ml.type is already correct */
 424                 list_move_tail(&target->list, &res->granted);
 425
 426                 BUG_ON(!target->lksb);
 427                 target->lksb->status = DLM_NORMAL;
 428
 429                 spin_unlock(&target->spinlock);
 430
 431                 __dlm_lockres_reserve_ast(res);
 432                 __dlm_queue_ast(dlm, target);
 433                 /* go back and check for more */
 434                 goto converting;
 435         }
 436
 437 leave:
 438         return;
 439 }
 440
 441 /* must have NO locks when calling this with res !=NULL * */
 442 void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 443 {
 444         if (res) {
 445                 spin_lock(&dlm->spinlock);
 446                 spin_lock(&res->spinlock);
 447                 __dlm_dirty_lockres(dlm, res);
 448                 spin_unlock(&res->spinlock);
 449                 spin_unlock(&dlm->spinlock);
 450         }
 451         wake_up(&dlm->dlm_thread_wq);
 452 }
 453
 454 void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 455 {
 456         assert_spin_locked(&dlm->spinlock);
 457         assert_spin_locked(&res->spinlock);
 458
 459         /* don't shuffle secondary queues */
 460         if ((res->owner == dlm->node_num)) {
 461                 if (res->state & (DLM_LOCK_RES_MIGRATING |
 462                                   DLM_LOCK_RES_BLOCK_DIRTY))
 463                     return;
 464
 465                 if (list_empty(&res->dirty)) {
 466                         /* ref for dirty_list */
 467                         dlm_lockres_get(res);
 468                         list_add_tail(&res->dirty, &dlm->dirty_list);
 469                         res->state |= DLM_LOCK_RES_DIRTY;
 470                 }
 471         }
 472
 473         mlog(0, "%s: res %.*s\n", dlm->name, res->lockname.len,
 474              res->lockname.name);
 475 }
 476
 477
 478 /* Launch the NM thread for the mounted volume */
 479 int dlm_launch_thread(struct dlm_ctxt *dlm)
 480 {
 481         mlog(0, "Starting dlm_thread...\n");
 482
 483         dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm_thread");
 484         if (IS_ERR(dlm->dlm_thread_task)) {
 485                 mlog_errno(PTR_ERR(dlm->dlm_thread_task));
 486                 dlm->dlm_thread_task = NULL;
 487                 return -EINVAL;
 488         }
 489
 490         return 0;
 491 }
 492
 493 void dlm_complete_thread(struct dlm_ctxt *dlm)
 494 {
 495         if (dlm->dlm_thread_task) {
 496                 mlog(ML_KTHREAD, "Waiting for dlm thread to exit\n");
 497                 kthread_stop(dlm->dlm_thread_task);
 498                 dlm->dlm_thread_task = NULL;
 499         }
 500 }
 501
 502 static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
 503 {
 504         int empty;
 505
 506         spin_lock(&dlm->spinlock);
 507         empty = list_empty(&dlm->dirty_list);
 508         spin_unlock(&dlm->spinlock);
 509
 510         return empty;
 511 }
 512
 513 static void dlm_flush_asts(struct dlm_ctxt *dlm)
 514 {
 515         int ret;
 516         struct dlm_lock *lock;
 517         struct dlm_lock_resource *res;
 518         u8 hi;
 519
 520         spin_lock(&dlm->ast_lock);
 521         while (!list_empty(&dlm->pending_asts)) {
 522                 lock = list_entry(dlm->pending_asts.next,
 523                                   struct dlm_lock, ast_list);
 524                 /* get an extra ref on lock */
 525                 dlm_lock_get(lock);
 526                 res = lock->lockres;
 527                 mlog(0, "%s: res %.*s, Flush AST for lock %u:%llu, type %d, "
 528                      "node %u\n", dlm->name, res->lockname.len,
 529                      res->lockname.name,
 530                      dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
 531                      dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
 532                      lock->ml.type, lock->ml.node);
 533
 534                 BUG_ON(!lock->ast_pending);
 535
 536                 /* remove from list (including ref) */
 537                 list_del_init(&lock->ast_list);
 538                 dlm_lock_put(lock);
 539                 spin_unlock(&dlm->ast_lock);
 540
 541                 if (lock->ml.node != dlm->node_num) {
 542                         ret = dlm_do_remote_ast(dlm, res, lock);
 543                         if (ret < 0)
 544                                 mlog_errno(ret);
 545                 } else
 546                         dlm_do_local_ast(dlm, res, lock);
 547
 548                 spin_lock(&dlm->ast_lock);
 549
 550                 /* possible that another ast was queued while
 551                  * we were delivering the last one */
 552                 if (!list_empty(&lock->ast_list)) {
 553                         mlog(0, "%s: res %.*s, AST queued while flushing last "
 554                              "one\n", dlm->name, res->lockname.len,
 555                              res->lockname.name);
 556                 } else
 557                         lock->ast_pending = 0;
 558
 559                 /* drop the extra ref.
 560                  * this may drop it completely. */
 561                 dlm_lock_put(lock);
 562                 dlm_lockres_release_ast(dlm, res);
 563         }
 564
 565         while (!list_empty(&dlm->pending_basts)) {
 566                 lock = list_entry(dlm->pending_basts.next,
 567                                   struct dlm_lock, bast_list);
 568                 /* get an extra ref on lock */
 569                 dlm_lock_get(lock);
 570                 res = lock->lockres;
 571
 572                 BUG_ON(!lock->bast_pending);
 573
 574                 /* get the highest blocked lock, and reset */
 575                 spin_lock(&lock->spinlock);
 576                 BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
 577                 hi = lock->ml.highest_blocked;
 578                 lock->ml.highest_blocked = LKM_IVMODE;
 579                 spin_unlock(&lock->spinlock);
 580
 581                 /* remove from list (including ref) */
 582                 list_del_init(&lock->bast_list);
 583                 dlm_lock_put(lock);
 584                 spin_unlock(&dlm->ast_lock);
 585
 586                 mlog(0, "%s: res %.*s, Flush BAST for lock %u:%llu, "
 587                      "blocked %d, node %u\n",
 588                      dlm->name, res->lockname.len, res->lockname.name,
 589                      dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
 590                      dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
 591                      hi, lock->ml.node);
 592
 593                 if (lock->ml.node != dlm->node_num) {
 594                         ret = dlm_send_proxy_bast(dlm, res, lock, hi);
 595                         if (ret < 0)
 596                                 mlog_errno(ret);
 597                 } else
 598                         dlm_do_local_bast(dlm, res, lock, hi);
 599
 600                 spin_lock(&dlm->ast_lock);
 601
 602                 /* possible that another bast was queued while
 603                  * we were delivering the last one */
 604                 if (!list_empty(&lock->bast_list)) {
 605                         mlog(0, "%s: res %.*s, BAST queued while flushing last "
 606                              "one\n", dlm->name, res->lockname.len,
 607                              res->lockname.name);
 608                 } else
 609                         lock->bast_pending = 0;
 610
 611                 /* drop the extra ref.
 612                  * this may drop it completely. */
 613                 dlm_lock_put(lock);
 614                 dlm_lockres_release_ast(dlm, res);
 615         }
 616         wake_up(&dlm->ast_wq);
 617         spin_unlock(&dlm->ast_lock);
 618 }
 619
 620
 621 #define DLM_THREAD_TIMEOUT_MS (4 * 1000)
 622 #define DLM_THREAD_MAX_DIRTY  100
 623 #define DLM_THREAD_MAX_ASTS   10
 624
 625 static int dlm_thread(void *data)
 626 {
 627         struct dlm_lock_resource *res;
 628         struct dlm_ctxt *dlm = data;
 629         unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
 630
 631         mlog(0, "dlm thread running for %s...\n", dlm->name);
 632
 633         while (!kthread_should_stop()) {
 634                 int n = DLM_THREAD_MAX_DIRTY;
 635
 636                 /* dlm_shutting_down is very point-in-time, but that
 637                  * doesn't matter as we'll just loop back around if we
 638                  * get false on the leading edge of a state
 639                  * transition. */
 640                 dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
 641
 642                 /* We really don't want to hold dlm->spinlock while
 643                  * calling dlm_shuffle_lists on each lockres that
 644                  * needs to have its queues adjusted and AST/BASTs
 645                  * run.  So let's pull each entry off the dirty_list
 646                  * and drop dlm->spinlock ASAP.  Once off the list,
 647                  * res->spinlock needs to be taken again to protect
 648                  * the queues while calling dlm_shuffle_lists.  */
 649                 spin_lock(&dlm->spinlock);
 650                 while (!list_empty(&dlm->dirty_list)) {
 651                         int delay = 0;
 652                         res = list_entry(dlm->dirty_list.next,
 653                                          struct dlm_lock_resource, dirty);
 654
 655                         /* peel a lockres off, remove it from the list,
 656                          * unset the dirty flag and drop the dlm lock */
 657                         BUG_ON(!res);
 658                         dlm_lockres_get(res);
 659
 660                         spin_lock(&res->spinlock);
 661                         /* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
 662                         list_del_init(&res->dirty);
 663                         spin_unlock(&res->spinlock);
 664                         spin_unlock(&dlm->spinlock);
 665                         /* Drop dirty_list ref */
 666                         dlm_lockres_put(res);
 667
 668                         /* lockres can be re-dirtied/re-added to the
 669                          * dirty_list in this gap, but that is ok */
 670
 671                         spin_lock(&dlm->ast_lock);
 672                         spin_lock(&res->spinlock);
 673                         if (res->owner != dlm->node_num) {
 674                                 __dlm_print_one_lock_resource(res);
 675                                 mlog(ML_ERROR, "%s: inprog %d, mig %d, reco %d,"
 676                                      " dirty %d\n", dlm->name,
 677                                      !!(res->state & DLM_LOCK_RES_IN_PROGRESS),
 678                                      !!(res->state & DLM_LOCK_RES_MIGRATING),
 679                                      !!(res->state & DLM_LOCK_RES_RECOVERING),
 680                                      !!(res->state & DLM_LOCK_RES_DIRTY));
 681                         }
 682                         BUG_ON(res->owner != dlm->node_num);
 683
 684                         /* it is now ok to move lockreses in these states
 685                          * to the dirty list, assuming that they will only be
 686                          * dirty for a short while. */
 687                         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
 688                         if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
 689                                           DLM_LOCK_RES_RECOVERING)) {
 690                                 /* move it to the tail and keep going */
 691                                 res->state &= ~DLM_LOCK_RES_DIRTY;
 692                                 spin_unlock(&res->spinlock);
 693                                 spin_unlock(&dlm->ast_lock);
 694                                 mlog(0, "%s: res %.*s, inprogress, delay list "
 695                                      "shuffle, state %d\n", dlm->name,
 696                                      res->lockname.len, res->lockname.name,
 697                                      res->state);
 698                                 delay = 1;
 699                                 goto in_progress;
 700                         }
 701
 702                         /* at this point the lockres is not migrating/
 703                          * recovering/in-progress.  we have the lockres
 704                          * spinlock and do NOT have the dlm lock.
 705                          * safe to reserve/queue asts and run the lists. */
 706
 707                         /* called while holding lockres lock */
 708                         dlm_shuffle_lists(dlm, res);
 709                         res->state &= ~DLM_LOCK_RES_DIRTY;
 710                         spin_unlock(&res->spinlock);
 711                         spin_unlock(&dlm->ast_lock);
 712
 713                         dlm_lockres_calc_usage(dlm, res);
 714
 715 in_progress:
 716
 717                         spin_lock(&dlm->spinlock);
 718                         /* if the lock was in-progress, stick
 719                          * it on the back of the list */
 720                         if (delay) {
 721                                 spin_lock(&res->spinlock);
 722                                 __dlm_dirty_lockres(dlm, res);
 723                                 spin_unlock(&res->spinlock);
 724                         }
 725                         dlm_lockres_put(res);
 726
 727                         /* unlikely, but we may need to give time to
 728                          * other tasks */
 729                         if (!--n) {
 730                                 mlog(0, "%s: Throttling dlm thread\n",
 731                                      dlm->name);
 732                                 break;
 733                         }
 734                 }
 735
 736                 spin_unlock(&dlm->spinlock);
 737                 dlm_flush_asts(dlm);
 738
 739                 /* yield and continue right away if there is more work to do */
 740                 if (!n) {
 741                         cond_resched();
 742                         continue;
 743                 }
 744
 745                 wait_event_interruptible_timeout(dlm->dlm_thread_wq,
 746                                                  !dlm_dirty_list_empty(dlm) ||
 747                                                  kthread_should_stop(),
 748                                                  timeout);
 749         }
 750
 751         mlog(0, "quitting DLM thread\n");
 752         return 0;
 753 }