fs/ocfs2/cluster/heartbeat.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * Copyright (C) 2004, 2005 Oracle.  All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public
  17  * License along with this program; if not, write to the
  18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  * Boston, MA 021110-1307, USA.
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/sched.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/module.h>
  26 #include <linux/fs.h>
  27 #include <linux/bio.h>
  28 #include <linux/blkdev.h>
  29 #include <linux/delay.h>
  30 #include <linux/file.h>
  31 #include <linux/kthread.h>
  32 #include <linux/configfs.h>
  33 #include <linux/random.h>
  34 #include <linux/crc32.h>
  35 #include <linux/time.h>
  36 #include <linux/debugfs.h>
  37
  38 #include "heartbeat.h"
  39 #include "tcp.h"
  40 #include "nodemanager.h"
  41 #include "quorum.h"
  42
  43 #include "masklog.h"
  44
  45
  46 /*
  47  * The first heartbeat pass had one global thread that would serialize all hb
  48  * callback calls.  This global serializing sem should only be removed once
  49  * we've made sure that all callees can deal with being called concurrently
  50  * from multiple hb region threads.
  51  */
  52 static DECLARE_RWSEM(o2hb_callback_sem);
  53
  54 /*
  55  * multiple hb threads are watching multiple regions.  A node is live
  56  * whenever any of the threads sees activity from the node in its region.
  57  */
  58 static DEFINE_SPINLOCK(o2hb_live_lock);
  59 static struct list_head o2hb_live_slots[O2NM_MAX_NODES];
  60 static unsigned long o2hb_live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
  61 static LIST_HEAD(o2hb_node_events);
  62 static DECLARE_WAIT_QUEUE_HEAD(o2hb_steady_queue);
  63
  64 #define O2HB_DEBUG_DIR                  "o2hb"
  65 #define O2HB_DEBUG_LIVENODES            "livenodes"
  66 static struct dentry *o2hb_debug_dir;
  67 static struct dentry *o2hb_debug_livenodes;
  68
  69 static LIST_HEAD(o2hb_all_regions);
  70
  71 static struct o2hb_callback {
  72         struct list_head list;
  73 } o2hb_callbacks[O2HB_NUM_CB];
  74
  75 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type);
  76
  77 #define O2HB_DEFAULT_BLOCK_BITS       9
  78
  79 unsigned int o2hb_dead_threshold = O2HB_DEFAULT_DEAD_THRESHOLD;
  80
  81 /* Only sets a new threshold if there are no active regions.
  82  *
  83  * No locking or otherwise interesting code is required for reading
  84  * o2hb_dead_threshold as it can't change once regions are active and
  85  * it's not interesting to anyone until then anyway. */
  86 static void o2hb_dead_threshold_set(unsigned int threshold)
  87 {
  88         if (threshold > O2HB_MIN_DEAD_THRESHOLD) {
  89                 spin_lock(&o2hb_live_lock);
  90                 if (list_empty(&o2hb_all_regions))
  91                         o2hb_dead_threshold = threshold;
  92                 spin_unlock(&o2hb_live_lock);
  93         }
  94 }
  95
  96 struct o2hb_node_event {
  97         struct list_head        hn_item;
  98         enum o2hb_callback_type hn_event_type;
  99         struct o2nm_node        *hn_node;
 100         int                     hn_node_num;
 101 };
 102
 103 struct o2hb_disk_slot {
 104         struct o2hb_disk_heartbeat_block *ds_raw_block;
 105         u8                      ds_node_num;
 106         u64                     ds_last_time;
 107         u64                     ds_last_generation;
 108         u16                     ds_equal_samples;
 109         u16                     ds_changed_samples;
 110         struct list_head        ds_live_item;
 111 };
 112
 113 /* each thread owns a region.. when we're asked to tear down the region
 114  * we ask the thread to stop, who cleans up the region */
 115 struct o2hb_region {
 116         struct config_item      hr_item;
 117
 118         struct list_head        hr_all_item;
 119         unsigned                hr_unclean_stop:1;
 120
 121         /* protected by the hr_callback_sem */
 122         struct task_struct      *hr_task;
 123
 124         unsigned int            hr_blocks;
 125         unsigned long long      hr_start_block;
 126
 127         unsigned int            hr_block_bits;
 128         unsigned int            hr_block_bytes;
 129
 130         unsigned int            hr_slots_per_page;
 131         unsigned int            hr_num_pages;
 132
 133         struct page             **hr_slot_data;
 134         struct block_device     *hr_bdev;
 135         struct o2hb_disk_slot   *hr_slots;
 136
 137         /* let the person setting up hb wait for it to return until it
 138          * has reached a 'steady' state.  This will be fixed when we have
 139          * a more complete api that doesn't lead to this sort of fragility. */
 140         atomic_t                hr_steady_iterations;
 141
 142         char                    hr_dev_name[BDEVNAME_SIZE];
 143
 144         unsigned int            hr_timeout_ms;
 145
 146         /* randomized as the region goes up and down so that a node
 147          * recognizes a node going up and down in one iteration */
 148         u64                     hr_generation;
 149
 150         struct delayed_work     hr_write_timeout_work;
 151         unsigned long           hr_last_timeout_start;
 152
 153         /* Used during o2hb_check_slot to hold a copy of the block
 154          * being checked because we temporarily have to zero out the
 155          * crc field. */
 156         struct o2hb_disk_heartbeat_block *hr_tmp_block;
 157 };
 158
 159 struct o2hb_bio_wait_ctxt {
 160         atomic_t          wc_num_reqs;
 161         struct completion wc_io_complete;
 162         int               wc_error;
 163 };
 164
 165 static void o2hb_write_timeout(struct work_struct *work)
 166 {
 167         struct o2hb_region *reg =
 168                 container_of(work, struct o2hb_region,
 169                              hr_write_timeout_work.work);
 170
 171         mlog(ML_ERROR, "Heartbeat write timeout to device %s after %u "
 172              "milliseconds\n", reg->hr_dev_name,
 173              jiffies_to_msecs(jiffies - reg->hr_last_timeout_start));
 174         o2quo_disk_timeout();
 175 }
 176
 177 static void o2hb_arm_write_timeout(struct o2hb_region *reg)
 178 {
 179         mlog(ML_HEARTBEAT, "Queue write timeout for %u ms\n",
 180              O2HB_MAX_WRITE_TIMEOUT_MS);
 181
 182         cancel_delayed_work(&reg->hr_write_timeout_work);
 183         reg->hr_last_timeout_start = jiffies;
 184         schedule_delayed_work(&reg->hr_write_timeout_work,
 185                               msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS));
 186 }
 187
 188 static void o2hb_disarm_write_timeout(struct o2hb_region *reg)
 189 {
 190         cancel_delayed_work(&reg->hr_write_timeout_work);
 191         flush_scheduled_work();
 192 }
 193
 194 static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc)
 195 {
 196         atomic_set(&wc->wc_num_reqs, 1);
 197         init_completion(&wc->wc_io_complete);
 198         wc->wc_error = 0;
 199 }
 200
 201 /* Used in error paths too */
 202 static inline void o2hb_bio_wait_dec(struct o2hb_bio_wait_ctxt *wc,
 203                                      unsigned int num)
 204 {
 205         /* sadly atomic_sub_and_test() isn't available on all platforms.  The
 206          * good news is that the fast path only completes one at a time */
 207         while(num--) {
 208                 if (atomic_dec_and_test(&wc->wc_num_reqs)) {
 209                         BUG_ON(num > 0);
 210                         complete(&wc->wc_io_complete);
 211                 }
 212         }
 213 }
 214
 215 static void o2hb_wait_on_io(struct o2hb_region *reg,
 216                             struct o2hb_bio_wait_ctxt *wc)
 217 {
 218         struct address_space *mapping = reg->hr_bdev->bd_inode->i_mapping;
 219
 220         blk_run_address_space(mapping);
 221         o2hb_bio_wait_dec(wc, 1);
 222
 223         wait_for_completion(&wc->wc_io_complete);
 224 }
 225
 226 static void o2hb_bio_end_io(struct bio *bio,
 227                            int error)
 228 {
 229         struct o2hb_bio_wait_ctxt *wc = bio->bi_private;
 230
 231         if (error) {
 232                 mlog(ML_ERROR, "IO Error %d\n", error);
 233                 wc->wc_error = error;
 234         }
 235
 236         o2hb_bio_wait_dec(wc, 1);
 237         bio_put(bio);
 238 }
 239
 240 /* Setup a Bio to cover I/O against num_slots slots starting at
 241  * start_slot. */
 242 static struct bio *o2hb_setup_one_bio(struct o2hb_region *reg,
 243                                       struct o2hb_bio_wait_ctxt *wc,
 244                                       unsigned int *current_slot,
 245                                       unsigned int max_slots)
 246 {
 247         int len, current_page;
 248         unsigned int vec_len, vec_start;
 249         unsigned int bits = reg->hr_block_bits;
 250         unsigned int spp = reg->hr_slots_per_page;
 251         unsigned int cs = *current_slot;
 252         struct bio *bio;
 253         struct page *page;
 254
 255         /* Testing has shown this allocation to take long enough under
 256          * GFP_KERNEL that the local node can get fenced. It would be
 257          * nicest if we could pre-allocate these bios and avoid this
 258          * all together. */
 259         bio = bio_alloc(GFP_ATOMIC, 16);
 260         if (!bio) {
 261                 mlog(ML_ERROR, "Could not alloc slots BIO!\n");
 262                 bio = ERR_PTR(-ENOMEM);
 263                 goto bail;
 264         }
 265
 266         /* Must put everything in 512 byte sectors for the bio... */
 267         bio->bi_sector = (reg->hr_start_block + cs) << (bits - 9);
 268         bio->bi_bdev = reg->hr_bdev;
 269         bio->bi_private = wc;
 270         bio->bi_end_io = o2hb_bio_end_io;
 271
 272         vec_start = (cs << bits) % PAGE_CACHE_SIZE;
 273         while(cs < max_slots) {
 274                 current_page = cs / spp;
 275                 page = reg->hr_slot_data[current_page];
 276
 277                 vec_len = min(PAGE_CACHE_SIZE - vec_start,
 278                               (max_slots-cs) * (PAGE_CACHE_SIZE/spp) );
 279
 280                 mlog(ML_HB_BIO, "page %d, vec_len = %u, vec_start = %u\n",
 281                      current_page, vec_len, vec_start);
 282
 283                 len = bio_add_page(bio, page, vec_len, vec_start);
 284                 if (len != vec_len) break;
 285
 286                 cs += vec_len / (PAGE_CACHE_SIZE/spp);
 287                 vec_start = 0;
 288         }
 289
 290 bail:
 291         *current_slot = cs;
 292         return bio;
 293 }
 294
 295 static int o2hb_read_slots(struct o2hb_region *reg,
 296                            unsigned int max_slots)
 297 {
 298         unsigned int current_slot=0;
 299         int status;
 300         struct o2hb_bio_wait_ctxt wc;
 301         struct bio *bio;
 302
 303         o2hb_bio_wait_init(&wc);
 304
 305         while(current_slot < max_slots) {
 306                 bio = o2hb_setup_one_bio(reg, &wc, &current_slot, max_slots);
 307                 if (IS_ERR(bio)) {
 308                         status = PTR_ERR(bio);
 309                         mlog_errno(status);
 310                         goto bail_and_wait;
 311                 }
 312
 313                 atomic_inc(&wc.wc_num_reqs);
 314                 submit_bio(READ, bio);
 315         }
 316
 317         status = 0;
 318
 319 bail_and_wait:
 320         o2hb_wait_on_io(reg, &wc);
 321         if (wc.wc_error && !status)
 322                 status = wc.wc_error;
 323
 324         return status;
 325 }
 326
 327 static int o2hb_issue_node_write(struct o2hb_region *reg,
 328                                  struct o2hb_bio_wait_ctxt *write_wc)
 329 {
 330         int status;
 331         unsigned int slot;
 332         struct bio *bio;
 333
 334         o2hb_bio_wait_init(write_wc);
 335
 336         slot = o2nm_this_node();
 337
 338         bio = o2hb_setup_one_bio(reg, write_wc, &slot, slot+1);
 339         if (IS_ERR(bio)) {
 340                 status = PTR_ERR(bio);
 341                 mlog_errno(status);
 342                 goto bail;
 343         }
 344
 345         atomic_inc(&write_wc->wc_num_reqs);
 346         submit_bio(WRITE, bio);
 347
 348         status = 0;
 349 bail:
 350         return status;
 351 }
 352
 353 static u32 o2hb_compute_block_crc_le(struct o2hb_region *reg,
 354                                      struct o2hb_disk_heartbeat_block *hb_block)
 355 {
 356         __le32 old_cksum;
 357         u32 ret;
 358
 359         /* We want to compute the block crc with a 0 value in the
 360          * hb_cksum field. Save it off here and replace after the
 361          * crc. */
 362         old_cksum = hb_block->hb_cksum;
 363         hb_block->hb_cksum = 0;
 364
 365         ret = crc32_le(0, (unsigned char *) hb_block, reg->hr_block_bytes);
 366
 367         hb_block->hb_cksum = old_cksum;
 368
 369         return ret;
 370 }
 371
 372 static void o2hb_dump_slot(struct o2hb_disk_heartbeat_block *hb_block)
 373 {
 374         mlog(ML_ERROR, "Dump slot information: seq = 0x%llx, node = %u, "
 375              "cksum = 0x%x, generation 0x%llx\n",
 376              (long long)le64_to_cpu(hb_block->hb_seq),
 377              hb_block->hb_node, le32_to_cpu(hb_block->hb_cksum),
 378              (long long)le64_to_cpu(hb_block->hb_generation));
 379 }
 380
 381 static int o2hb_verify_crc(struct o2hb_region *reg,
 382                            struct o2hb_disk_heartbeat_block *hb_block)
 383 {
 384         u32 read, computed;
 385
 386         read = le32_to_cpu(hb_block->hb_cksum);
 387         computed = o2hb_compute_block_crc_le(reg, hb_block);
 388
 389         return read == computed;
 390 }
 391
 392 /* We want to make sure that nobody is heartbeating on top of us --
 393  * this will help detect an invalid configuration. */
 394 static int o2hb_check_last_timestamp(struct o2hb_region *reg)
 395 {
 396         int node_num, ret;
 397         struct o2hb_disk_slot *slot;
 398         struct o2hb_disk_heartbeat_block *hb_block;
 399
 400         node_num = o2nm_this_node();
 401
 402         ret = 1;
 403         slot = &reg->hr_slots[node_num];
 404         /* Don't check on our 1st timestamp */
 405         if (slot->ds_last_time) {
 406                 hb_block = slot->ds_raw_block;
 407
 408                 if (le64_to_cpu(hb_block->hb_seq) != slot->ds_last_time)
 409                         ret = 0;
 410         }
 411
 412         return ret;
 413 }
 414
 415 static inline void o2hb_prepare_block(struct o2hb_region *reg,
 416                                       u64 generation)
 417 {
 418         int node_num;
 419         u64 cputime;
 420         struct o2hb_disk_slot *slot;
 421         struct o2hb_disk_heartbeat_block *hb_block;
 422
 423         node_num = o2nm_this_node();
 424         slot = &reg->hr_slots[node_num];
 425
 426         hb_block = (struct o2hb_disk_heartbeat_block *)slot->ds_raw_block;
 427         memset(hb_block, 0, reg->hr_block_bytes);
 428         /* TODO: time stuff */
 429         cputime = CURRENT_TIME.tv_sec;
 430         if (!cputime)
 431                 cputime = 1;
 432
 433         hb_block->hb_seq = cpu_to_le64(cputime);
 434         hb_block->hb_node = node_num;
 435         hb_block->hb_generation = cpu_to_le64(generation);
 436         hb_block->hb_dead_ms = cpu_to_le32(o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS);
 437
 438         /* This step must always happen last! */
 439         hb_block->hb_cksum = cpu_to_le32(o2hb_compute_block_crc_le(reg,
 440                                                                    hb_block));
 441
 442         mlog(ML_HB_BIO, "our node generation = 0x%llx, cksum = 0x%x\n",
 443              (long long)generation,
 444              le32_to_cpu(hb_block->hb_cksum));
 445 }
 446
 447 static void o2hb_fire_callbacks(struct o2hb_callback *hbcall,
 448                                 struct o2nm_node *node,
 449                                 int idx)
 450 {
 451         struct list_head *iter;
 452         struct o2hb_callback_func *f;
 453
 454         list_for_each(iter, &hbcall->list) {
 455                 f = list_entry(iter, struct o2hb_callback_func, hc_item);
 456                 mlog(ML_HEARTBEAT, "calling funcs %p\n", f);
 457                 (f->hc_func)(node, idx, f->hc_data);
 458         }
 459 }
 460
 461 /* Will run the list in order until we process the passed event */
 462 static void o2hb_run_event_list(struct o2hb_node_event *queued_event)
 463 {
 464         int empty;
 465         struct o2hb_callback *hbcall;
 466         struct o2hb_node_event *event;
 467
 468         spin_lock(&o2hb_live_lock);
 469         empty = list_empty(&queued_event->hn_item);
 470         spin_unlock(&o2hb_live_lock);
 471         if (empty)
 472                 return;
 473
 474         /* Holding callback sem assures we don't alter the callback
 475          * lists when doing this, and serializes ourselves with other
 476          * processes wanting callbacks. */
 477         down_write(&o2hb_callback_sem);
 478
 479         spin_lock(&o2hb_live_lock);
 480         while (!list_empty(&o2hb_node_events)
 481                && !list_empty(&queued_event->hn_item)) {
 482                 event = list_entry(o2hb_node_events.next,
 483                                    struct o2hb_node_event,
 484                                    hn_item);
 485                 list_del_init(&event->hn_item);
 486                 spin_unlock(&o2hb_live_lock);
 487
 488                 mlog(ML_HEARTBEAT, "Node %s event for %d\n",
 489                      event->hn_event_type == O2HB_NODE_UP_CB ? "UP" : "DOWN",
 490                      event->hn_node_num);
 491
 492                 hbcall = hbcall_from_type(event->hn_event_type);
 493
 494                 /* We should *never* have gotten on to the list with a
 495                  * bad type... This isn't something that we should try
 496                  * to recover from. */
 497                 BUG_ON(IS_ERR(hbcall));
 498
 499                 o2hb_fire_callbacks(hbcall, event->hn_node, event->hn_node_num);
 500
 501                 spin_lock(&o2hb_live_lock);
 502         }
 503         spin_unlock(&o2hb_live_lock);
 504
 505         up_write(&o2hb_callback_sem);
 506 }
 507
 508 static void o2hb_queue_node_event(struct o2hb_node_event *event,
 509                                   enum o2hb_callback_type type,
 510                                   struct o2nm_node *node,
 511                                   int node_num)
 512 {
 513         assert_spin_locked(&o2hb_live_lock);
 514
 515         event->hn_event_type = type;
 516         event->hn_node = node;
 517         event->hn_node_num = node_num;
 518
 519         mlog(ML_HEARTBEAT, "Queue node %s event for node %d\n",
 520              type == O2HB_NODE_UP_CB ? "UP" : "DOWN", node_num);
 521
 522         list_add_tail(&event->hn_item, &o2hb_node_events);
 523 }
 524
 525 static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
 526 {
 527         struct o2hb_node_event event =
 528                 { .hn_item = LIST_HEAD_INIT(event.hn_item), };
 529         struct o2nm_node *node;
 530
 531         node = o2nm_get_node_by_num(slot->ds_node_num);
 532         if (!node)
 533                 return;
 534
 535         spin_lock(&o2hb_live_lock);
 536         if (!list_empty(&slot->ds_live_item)) {
 537                 mlog(ML_HEARTBEAT, "Shutdown, node %d leaves region\n",
 538                      slot->ds_node_num);
 539
 540                 list_del_init(&slot->ds_live_item);
 541
 542                 if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
 543                         clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);
 544
 545                         o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
 546                                               slot->ds_node_num);
 547                 }
 548         }
 549         spin_unlock(&o2hb_live_lock);
 550
 551         o2hb_run_event_list(&event);
 552
 553         o2nm_node_put(node);
 554 }
 555
 556 static int o2hb_check_slot(struct o2hb_region *reg,
 557                            struct o2hb_disk_slot *slot)
 558 {
 559         int changed = 0, gen_changed = 0;
 560         struct o2hb_node_event event =
 561                 { .hn_item = LIST_HEAD_INIT(event.hn_item), };
 562         struct o2nm_node *node;
 563         struct o2hb_disk_heartbeat_block *hb_block = reg->hr_tmp_block;
 564         u64 cputime;
 565         unsigned int dead_ms = o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS;
 566         unsigned int slot_dead_ms;
 567
 568         memcpy(hb_block, slot->ds_raw_block, reg->hr_block_bytes);
 569
 570         /* Is this correct? Do we assume that the node doesn't exist
 571          * if we're not configured for him? */
 572         node = o2nm_get_node_by_num(slot->ds_node_num);
 573         if (!node)
 574                 return 0;
 575
 576         if (!o2hb_verify_crc(reg, hb_block)) {
 577                 /* all paths from here will drop o2hb_live_lock for
 578                  * us. */
 579                 spin_lock(&o2hb_live_lock);
 580
 581                 /* Don't print an error on the console in this case -
 582                  * a freshly formatted heartbeat area will not have a
 583                  * crc set on it. */
 584                 if (list_empty(&slot->ds_live_item))
 585                         goto out;
 586
 587                 /* The node is live but pushed out a bad crc. We
 588                  * consider it a transient miss but don't populate any
 589                  * other values as they may be junk. */
 590                 mlog(ML_ERROR, "Node %d has written a bad crc to %s\n",
 591                      slot->ds_node_num, reg->hr_dev_name);
 592                 o2hb_dump_slot(hb_block);
 593
 594                 slot->ds_equal_samples++;
 595                 goto fire_callbacks;
 596         }
 597
 598         /* we don't care if these wrap.. the state transitions below
 599          * clear at the right places */
 600         cputime = le64_to_cpu(hb_block->hb_seq);
 601         if (slot->ds_last_time != cputime)
 602                 slot->ds_changed_samples++;
 603         else
 604                 slot->ds_equal_samples++;
 605         slot->ds_last_time = cputime;
 606
 607         /* The node changed heartbeat generations. We assume this to
 608          * mean it dropped off but came back before we timed out. We
 609          * want to consider it down for the time being but don't want
 610          * to lose any changed_samples state we might build up to
 611          * considering it live again. */
 612         if (slot->ds_last_generation != le64_to_cpu(hb_block->hb_generation)) {
 613                 gen_changed = 1;
 614                 slot->ds_equal_samples = 0;
 615                 mlog(ML_HEARTBEAT, "Node %d changed generation (0x%llx "
 616                      "to 0x%llx)\n", slot->ds_node_num,
 617                      (long long)slot->ds_last_generation,
 618                      (long long)le64_to_cpu(hb_block->hb_generation));
 619         }
 620
 621         slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);
 622
 623         mlog(ML_HEARTBEAT, "Slot %d gen 0x%llx cksum 0x%x "
 624              "seq %llu last %llu changed %u equal %u\n",
 625              slot->ds_node_num, (long long)slot->ds_last_generation,
 626              le32_to_cpu(hb_block->hb_cksum),
 627              (unsigned long long)le64_to_cpu(hb_block->hb_seq),
 628              (unsigned long long)slot->ds_last_time, slot->ds_changed_samples,
 629              slot->ds_equal_samples);
 630
 631         spin_lock(&o2hb_live_lock);
 632
 633 fire_callbacks:
 634         /* dead nodes only come to life after some number of
 635          * changes at any time during their dead time */
 636         if (list_empty(&slot->ds_live_item) &&
 637             slot->ds_changed_samples >= O2HB_LIVE_THRESHOLD) {
 638                 mlog(ML_HEARTBEAT, "Node %d (id 0x%llx) joined my region\n",
 639                      slot->ds_node_num, (long long)slot->ds_last_generation);
 640
 641                 /* first on the list generates a callback */
 642                 if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
 643                         set_bit(slot->ds_node_num, o2hb_live_node_bitmap);
 644
 645                         o2hb_queue_node_event(&event, O2HB_NODE_UP_CB, node,
 646                                               slot->ds_node_num);
 647
 648                         changed = 1;
 649                 }
 650
 651                 list_add_tail(&slot->ds_live_item,
 652                               &o2hb_live_slots[slot->ds_node_num]);
 653
 654                 slot->ds_equal_samples = 0;
 655
 656                 /* We want to be sure that all nodes agree on the
 657                  * number of milliseconds before a node will be
 658                  * considered dead. The self-fencing timeout is
 659                  * computed from this value, and a discrepancy might
 660                  * result in heartbeat calling a node dead when it
 661                  * hasn't self-fenced yet. */
 662                 slot_dead_ms = le32_to_cpu(hb_block->hb_dead_ms);
 663                 if (slot_dead_ms && slot_dead_ms != dead_ms) {
 664                         /* TODO: Perhaps we can fail the region here. */
 665                         mlog(ML_ERROR, "Node %d on device %s has a dead count "
 666                              "of %u ms, but our count is %u ms.\n"
 667                              "Please double check your configuration values "
 668                              "for 'O2CB_HEARTBEAT_THRESHOLD'\n",
 669                              slot->ds_node_num, reg->hr_dev_name, slot_dead_ms,
 670                              dead_ms);
 671                 }
 672                 goto out;
 673         }
 674
 675         /* if the list is dead, we're done.. */
 676         if (list_empty(&slot->ds_live_item))
 677                 goto out;
 678
 679         /* live nodes only go dead after enough consequtive missed
 680          * samples..  reset the missed counter whenever we see
 681          * activity */
 682         if (slot->ds_equal_samples >= o2hb_dead_threshold || gen_changed) {
 683                 mlog(ML_HEARTBEAT, "Node %d left my region\n",
 684                      slot->ds_node_num);
 685
 686                 /* last off the live_slot generates a callback */
 687                 list_del_init(&slot->ds_live_item);
 688                 if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
 689                         clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);
 690
 691                         o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
 692                                               slot->ds_node_num);
 693
 694                         changed = 1;
 695                 }
 696
 697                 /* We don't clear this because the node is still
 698                  * actually writing new blocks. */
 699                 if (!gen_changed)
 700                         slot->ds_changed_samples = 0;
 701                 goto out;
 702         }
 703         if (slot->ds_changed_samples) {
 704                 slot->ds_changed_samples = 0;
 705                 slot->ds_equal_samples = 0;
 706         }
 707 out:
 708         spin_unlock(&o2hb_live_lock);
 709
 710         o2hb_run_event_list(&event);
 711
 712         o2nm_node_put(node);
 713         return changed;
 714 }
 715
 716 /* This could be faster if we just implmented a find_last_bit, but I
 717  * don't think the circumstances warrant it. */
 718 static int o2hb_highest_node(unsigned long *nodes,
 719                              int numbits)
 720 {
 721         int highest, node;
 722
 723         highest = numbits;
 724         node = -1;
 725         while ((node = find_next_bit(nodes, numbits, node + 1)) != -1) {
 726                 if (node >= numbits)
 727                         break;
 728
 729                 highest = node;
 730         }
 731
 732         return highest;
 733 }
 734
 735 static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 736 {
 737         int i, ret, highest_node, change = 0;
 738         unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
 739         struct o2hb_bio_wait_ctxt write_wc;
 740
 741         ret = o2nm_configured_node_map(configured_nodes,
 742                                        sizeof(configured_nodes));
 743         if (ret) {
 744                 mlog_errno(ret);
 745                 return ret;
 746         }
 747
 748         highest_node = o2hb_highest_node(configured_nodes, O2NM_MAX_NODES);
 749         if (highest_node >= O2NM_MAX_NODES) {
 750                 mlog(ML_NOTICE, "ocfs2_heartbeat: no configured nodes found!\n");
 751                 return -EINVAL;
 752         }
 753
 754         /* No sense in reading the slots of nodes that don't exist
 755          * yet. Of course, if the node definitions have holes in them
 756          * then we're reading an empty slot anyway... Consider this
 757          * best-effort. */
 758         ret = o2hb_read_slots(reg, highest_node + 1);
 759         if (ret < 0) {
 760                 mlog_errno(ret);
 761                 return ret;
 762         }
 763
 764         /* With an up to date view of the slots, we can check that no
 765          * other node has been improperly configured to heartbeat in
 766          * our slot. */
 767         if (!o2hb_check_last_timestamp(reg))
 768                 mlog(ML_ERROR, "Device \"%s\": another node is heartbeating "
 769                      "in our slot!\n", reg->hr_dev_name);
 770
 771         /* fill in the proper info for our next heartbeat */
 772         o2hb_prepare_block(reg, reg->hr_generation);
 773
 774         /* And fire off the write. Note that we don't wait on this I/O
 775          * until later. */
 776         ret = o2hb_issue_node_write(reg, &write_wc);
 777         if (ret < 0) {
 778                 mlog_errno(ret);
 779                 return ret;
 780         }
 781
 782         i = -1;
 783         while((i = find_next_bit(configured_nodes, O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
 784
 785                 change |= o2hb_check_slot(reg, &reg->hr_slots[i]);
 786         }
 787
 788         /*
 789          * We have to be sure we've advertised ourselves on disk
 790          * before we can go to steady state.  This ensures that
 791          * people we find in our steady state have seen us.
 792          */
 793         o2hb_wait_on_io(reg, &write_wc);
 794         if (write_wc.wc_error) {
 795                 /* Do not re-arm the write timeout on I/O error - we
 796                  * can't be sure that the new block ever made it to
 797                  * disk */
 798                 mlog(ML_ERROR, "Write error %d on device \"%s\"\n",
 799                      write_wc.wc_error, reg->hr_dev_name);
 800                 return write_wc.wc_error;
 801         }
 802
 803         o2hb_arm_write_timeout(reg);
 804
 805         /* let the person who launched us know when things are steady */
 806         if (!change && (atomic_read(&reg->hr_steady_iterations) != 0)) {
 807                 if (atomic_dec_and_test(&reg->hr_steady_iterations))
 808                         wake_up(&o2hb_steady_queue);
 809         }
 810
 811         return 0;
 812 }
 813
 814 /* Subtract b from a, storing the result in a. a *must* have a larger
 815  * value than b. */
 816 static void o2hb_tv_subtract(struct timeval *a,
 817                              struct timeval *b)
 818 {
 819         /* just return 0 when a is after b */
 820         if (a->tv_sec < b->tv_sec ||
 821             (a->tv_sec == b->tv_sec && a->tv_usec < b->tv_usec)) {
 822                 a->tv_sec = 0;
 823                 a->tv_usec = 0;
 824                 return;
 825         }
 826
 827         a->tv_sec -= b->tv_sec;
 828         a->tv_usec -= b->tv_usec;
 829         while ( a->tv_usec < 0 ) {
 830                 a->tv_sec--;
 831                 a->tv_usec += 1000000;
 832         }
 833 }
 834
 835 static unsigned int o2hb_elapsed_msecs(struct timeval *start,
 836                                        struct timeval *end)
 837 {
 838         struct timeval res = *end;
 839
 840         o2hb_tv_subtract(&res, start);
 841
 842         return res.tv_sec * 1000 + res.tv_usec / 1000;
 843 }
 844
 845 /*
 846  * we ride the region ref that the region dir holds.  before the region
 847  * dir is removed and drops it ref it will wait to tear down this
 848  * thread.
 849  */
 850 static int o2hb_thread(void *data)
 851 {
 852         int i, ret;
 853         struct o2hb_region *reg = data;
 854         struct o2hb_bio_wait_ctxt write_wc;
 855         struct timeval before_hb, after_hb;
 856         unsigned int elapsed_msec;
 857
 858         mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread running\n");
 859
 860         set_user_nice(current, -20);
 861
 862         while (!kthread_should_stop() && !reg->hr_unclean_stop) {
 863                 /* We track the time spent inside
 864                  * o2hb_do_disk_heartbeat so that we avoid more than
 865                  * hr_timeout_ms between disk writes. On busy systems
 866                  * this should result in a heartbeat which is less
 867                  * likely to time itself out. */
 868                 do_gettimeofday(&before_hb);
 869
 870                 i = 0;
 871                 do {
 872                         ret = o2hb_do_disk_heartbeat(reg);
 873                 } while (ret && ++i < 2);
 874
 875                 do_gettimeofday(&after_hb);
 876                 elapsed_msec = o2hb_elapsed_msecs(&before_hb, &after_hb);
 877
 878                 mlog(ML_HEARTBEAT,
 879                      "start = %lu.%lu, end = %lu.%lu, msec = %u\n",
 880                      before_hb.tv_sec, (unsigned long) before_hb.tv_usec,
 881                      after_hb.tv_sec, (unsigned long) after_hb.tv_usec,
 882                      elapsed_msec);
 883
 884                 if (elapsed_msec < reg->hr_timeout_ms) {
 885                         /* the kthread api has blocked signals for us so no
 886                          * need to record the return value. */
 887                         msleep_interruptible(reg->hr_timeout_ms - elapsed_msec);
 888                 }
 889         }
 890
 891         o2hb_disarm_write_timeout(reg);
 892
 893         /* unclean stop is only used in very bad situation */
 894         for(i = 0; !reg->hr_unclean_stop && i < reg->hr_blocks; i++)
 895                 o2hb_shutdown_slot(&reg->hr_slots[i]);
 896
 897         /* Explicit down notification - avoid forcing the other nodes
 898          * to timeout on this region when we could just as easily
 899          * write a clear generation - thus indicating to them that
 900          * this node has left this region.
 901          *
 902          * XXX: Should we skip this on unclean_stop? */
 903         o2hb_prepare_block(reg, 0);
 904         ret = o2hb_issue_node_write(reg, &write_wc);
 905         if (ret == 0) {
 906                 o2hb_wait_on_io(reg, &write_wc);
 907         } else {
 908                 mlog_errno(ret);
 909         }
 910
 911         mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread exiting\n");
 912
 913         return 0;
 914 }
 915
 916 #ifdef CONFIG_DEBUG_FS
 917 static int o2hb_debug_open(struct inode *inode, struct file *file)
 918 {
 919         unsigned long map[BITS_TO_LONGS(O2NM_MAX_NODES)];
 920         char *buf = NULL;
 921         int i = -1;
 922         int out = 0;
 923
 924         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 925         if (!buf)
 926                 goto bail;
 927
 928         o2hb_fill_node_map(map, sizeof(map));
 929
 930         while ((i = find_next_bit(map, O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES)
 931                 out += snprintf(buf + out, PAGE_SIZE - out, "%d ", i);
 932         out += snprintf(buf + out, PAGE_SIZE - out, "\n");
 933
 934         i_size_write(inode, out);
 935
 936         file->private_data = buf;
 937
 938         return 0;
 939 bail:
 940         return -ENOMEM;
 941 }
 942
 943 static int o2hb_debug_release(struct inode *inode, struct file *file)
 944 {
 945         kfree(file->private_data);
 946         return 0;
 947 }
 948
 949 static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
 950                                  size_t nbytes, loff_t *ppos)
 951 {
 952         return simple_read_from_buffer(buf, nbytes, ppos, file->private_data,
 953                                        i_size_read(file->f_mapping->host));
 954 }
 955 #else
 956 static int o2hb_debug_open(struct inode *inode, struct file *file)
 957 {
 958         return 0;
 959 }
 960 static int o2hb_debug_release(struct inode *inode, struct file *file)
 961 {
 962         return 0;
 963 }
 964 static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
 965                                size_t nbytes, loff_t *ppos)
 966 {
 967         return 0;
 968 }
 969 #endif  /* CONFIG_DEBUG_FS */
 970
 971 static const struct file_operations o2hb_debug_fops = {
 972         .open =         o2hb_debug_open,
 973         .release =      o2hb_debug_release,
 974         .read =         o2hb_debug_read,
 975         .llseek =       generic_file_llseek,
 976 };
 977
 978 void o2hb_exit(void)
 979 {
 980         if (o2hb_debug_livenodes)
 981                 debugfs_remove(o2hb_debug_livenodes);
 982         if (o2hb_debug_dir)
 983                 debugfs_remove(o2hb_debug_dir);
 984 }
 985
 986 int o2hb_init(void)
 987 {
 988         int i;
 989
 990         for (i = 0; i < ARRAY_SIZE(o2hb_callbacks); i++)
 991                 INIT_LIST_HEAD(&o2hb_callbacks[i].list);
 992
 993         for (i = 0; i < ARRAY_SIZE(o2hb_live_slots); i++)
 994                 INIT_LIST_HEAD(&o2hb_live_slots[i]);
 995
 996         INIT_LIST_HEAD(&o2hb_node_events);
 997
 998         memset(o2hb_live_node_bitmap, 0, sizeof(o2hb_live_node_bitmap));
 999
1000         o2hb_debug_dir = debugfs_create_dir(O2HB_DEBUG_DIR, NULL);
1001         if (!o2hb_debug_dir) {
1002                 mlog_errno(-ENOMEM);
1003                 return -ENOMEM;
1004         }
1005
1006         o2hb_debug_livenodes = debugfs_create_file(O2HB_DEBUG_LIVENODES,
1007                                                    S_IFREG|S_IRUSR,
1008                                                    o2hb_debug_dir, NULL,
1009                                                    &o2hb_debug_fops);
1010         if (!o2hb_debug_livenodes) {
1011                 mlog_errno(-ENOMEM);
1012                 debugfs_remove(o2hb_debug_dir);
1013                 return -ENOMEM;
1014         }
1015
1016         return 0;
1017 }
1018
1019 /* if we're already in a callback then we're already serialized by the sem */
1020 static void o2hb_fill_node_map_from_callback(unsigned long *map,
1021                                              unsigned bytes)
1022 {
1023         BUG_ON(bytes < (BITS_TO_LONGS(O2NM_MAX_NODES) * sizeof(unsigned long)));
1024
1025         memcpy(map, &o2hb_live_node_bitmap, bytes);
1026 }
1027
1028 /*
1029  * get a map of all nodes that are heartbeating in any regions
1030  */
1031 void o2hb_fill_node_map(unsigned long *map, unsigned bytes)
1032 {
1033         /* callers want to serialize this map and callbacks so that they
1034          * can trust that they don't miss nodes coming to the party */
1035         down_read(&o2hb_callback_sem);
1036         spin_lock(&o2hb_live_lock);
1037         o2hb_fill_node_map_from_callback(map, bytes);
1038         spin_unlock(&o2hb_live_lock);
1039         up_read(&o2hb_callback_sem);
1040 }
1041 EXPORT_SYMBOL_GPL(o2hb_fill_node_map);
1042
1043 /*
1044  * heartbeat configfs bits.  The heartbeat set is a default set under
1045  * the cluster set in nodemanager.c.
1046  */
1047
1048 static struct o2hb_region *to_o2hb_region(struct config_item *item)
1049 {
1050         return item ? container_of(item, struct o2hb_region, hr_item) : NULL;
1051 }
1052
1053 /* drop_item only drops its ref after killing the thread, nothing should
1054  * be using the region anymore.  this has to clean up any state that
1055  * attributes might have built up. */
1056 static void o2hb_region_release(struct config_item *item)
1057 {
1058         int i;
1059         struct page *page;
1060         struct o2hb_region *reg = to_o2hb_region(item);
1061
1062         if (reg->hr_tmp_block)
1063                 kfree(reg->hr_tmp_block);
1064
1065         if (reg->hr_slot_data) {
1066                 for (i = 0; i < reg->hr_num_pages; i++) {
1067                         page = reg->hr_slot_data[i];
1068                         if (page)
1069                                 __free_page(page);
1070                 }
1071                 kfree(reg->hr_slot_data);
1072         }
1073
1074         if (reg->hr_bdev)
1075                 blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
1076
1077         if (reg->hr_slots)
1078                 kfree(reg->hr_slots);
1079
1080         spin_lock(&o2hb_live_lock);
1081         list_del(&reg->hr_all_item);
1082         spin_unlock(&o2hb_live_lock);
1083
1084         kfree(reg);
1085 }
1086
1087 static int o2hb_read_block_input(struct o2hb_region *reg,
1088                                  const char *page,
1089                                  size_t count,
1090                                  unsigned long *ret_bytes,
1091                                  unsigned int *ret_bits)
1092 {
1093         unsigned long bytes;
1094         char *p = (char *)page;
1095
1096         bytes = simple_strtoul(p, &p, 0);
1097         if (!p || (*p && (*p != '\n')))
1098                 return -EINVAL;
1099
1100         /* Heartbeat and fs min / max block sizes are the same. */
1101         if (bytes > 4096 || bytes < 512)
1102                 return -ERANGE;
1103         if (hweight16(bytes) != 1)
1104                 return -EINVAL;
1105
1106         if (ret_bytes)
1107                 *ret_bytes = bytes;
1108         if (ret_bits)
1109                 *ret_bits = ffs(bytes) - 1;
1110
1111         return 0;
1112 }
1113
1114 static ssize_t o2hb_region_block_bytes_read(struct o2hb_region *reg,
1115                                             char *page)
1116 {
1117         return sprintf(page, "%u\n", reg->hr_block_bytes);
1118 }
1119
1120 static ssize_t o2hb_region_block_bytes_write(struct o2hb_region *reg,
1121                                              const char *page,
1122                                              size_t count)
1123 {
1124         int status;
1125         unsigned long block_bytes;
1126         unsigned int block_bits;
1127
1128         if (reg->hr_bdev)
1129                 return -EINVAL;
1130
1131         status = o2hb_read_block_input(reg, page, count,
1132                                        &block_bytes, &block_bits);
1133         if (status)
1134                 return status;
1135
1136         reg->hr_block_bytes = (unsigned int)block_bytes;
1137         reg->hr_block_bits = block_bits;
1138
1139         return count;
1140 }
1141
1142 static ssize_t o2hb_region_start_block_read(struct o2hb_region *reg,
1143                                             char *page)
1144 {
1145         return sprintf(page, "%llu\n", reg->hr_start_block);
1146 }
1147
1148 static ssize_t o2hb_region_start_block_write(struct o2hb_region *reg,
1149                                              const char *page,
1150                                              size_t count)
1151 {
1152         unsigned long long tmp;
1153         char *p = (char *)page;
1154
1155         if (reg->hr_bdev)
1156                 return -EINVAL;
1157
1158         tmp = simple_strtoull(p, &p, 0);
1159         if (!p || (*p && (*p != '\n')))
1160                 return -EINVAL;
1161
1162         reg->hr_start_block = tmp;
1163
1164         return count;
1165 }
1166
1167 static ssize_t o2hb_region_blocks_read(struct o2hb_region *reg,
1168                                        char *page)
1169 {
1170         return sprintf(page, "%d\n", reg->hr_blocks);
1171 }
1172
1173 static ssize_t o2hb_region_blocks_write(struct o2hb_region *reg,
1174                                         const char *page,
1175                                         size_t count)
1176 {
1177         unsigned long tmp;
1178         char *p = (char *)page;
1179
1180         if (reg->hr_bdev)
1181                 return -EINVAL;
1182
1183         tmp = simple_strtoul(p, &p, 0);
1184         if (!p || (*p && (*p != '\n')))
1185                 return -EINVAL;
1186
1187         if (tmp > O2NM_MAX_NODES || tmp == 0)
1188                 return -ERANGE;
1189
1190         reg->hr_blocks = (unsigned int)tmp;
1191
1192         return count;
1193 }
1194
1195 static ssize_t o2hb_region_dev_read(struct o2hb_region *reg,
1196                                     char *page)
1197 {
1198         unsigned int ret = 0;
1199
1200         if (reg->hr_bdev)
1201                 ret = sprintf(page, "%s\n", reg->hr_dev_name);
1202
1203         return ret;
1204 }
1205
1206 static void o2hb_init_region_params(struct o2hb_region *reg)
1207 {
1208         reg->hr_slots_per_page = PAGE_CACHE_SIZE >> reg->hr_block_bits;
1209         reg->hr_timeout_ms = O2HB_REGION_TIMEOUT_MS;
1210
1211         mlog(ML_HEARTBEAT, "hr_start_block = %llu, hr_blocks = %u\n",
1212              reg->hr_start_block, reg->hr_blocks);
1213         mlog(ML_HEARTBEAT, "hr_block_bytes = %u, hr_block_bits = %u\n",
1214              reg->hr_block_bytes, reg->hr_block_bits);
1215         mlog(ML_HEARTBEAT, "hr_timeout_ms = %u\n", reg->hr_timeout_ms);
1216         mlog(ML_HEARTBEAT, "dead threshold = %u\n", o2hb_dead_threshold);
1217 }
1218
1219 static int o2hb_map_slot_data(struct o2hb_region *reg)
1220 {
1221         int i, j;
1222         unsigned int last_slot;
1223         unsigned int spp = reg->hr_slots_per_page;
1224         struct page *page;
1225         char *raw;
1226         struct o2hb_disk_slot *slot;
1227
1228         reg->hr_tmp_block = kmalloc(reg->hr_block_bytes, GFP_KERNEL);
1229         if (reg->hr_tmp_block == NULL) {
1230                 mlog_errno(-ENOMEM);
1231                 return -ENOMEM;
1232         }
1233
1234         reg->hr_slots = kcalloc(reg->hr_blocks,
1235                                 sizeof(struct o2hb_disk_slot), GFP_KERNEL);
1236         if (reg->hr_slots == NULL) {
1237                 mlog_errno(-ENOMEM);
1238                 return -ENOMEM;
1239         }
1240
1241         for(i = 0; i < reg->hr_blocks; i++) {
1242                 slot = &reg->hr_slots[i];
1243                 slot->ds_node_num = i;
1244                 INIT_LIST_HEAD(&slot->ds_live_item);
1245                 slot->ds_raw_block = NULL;
1246         }
1247
1248         reg->hr_num_pages = (reg->hr_blocks + spp - 1) / spp;
1249         mlog(ML_HEARTBEAT, "Going to require %u pages to cover %u blocks "
1250                            "at %u blocks per page\n",
1251              reg->hr_num_pages, reg->hr_blocks, spp);
1252
1253         reg->hr_slot_data = kcalloc(reg->hr_num_pages, sizeof(struct page *),
1254                                     GFP_KERNEL);
1255         if (!reg->hr_slot_data) {
1256                 mlog_errno(-ENOMEM);
1257                 return -ENOMEM;
1258         }
1259
1260         for(i = 0; i < reg->hr_num_pages; i++) {
1261                 page = alloc_page(GFP_KERNEL);
1262                 if (!page) {
1263                         mlog_errno(-ENOMEM);
1264                         return -ENOMEM;
1265                 }
1266
1267                 reg->hr_slot_data[i] = page;
1268
1269                 last_slot = i * spp;
1270                 raw = page_address(page);
1271                 for (j = 0;
1272                      (j < spp) && ((j + last_slot) < reg->hr_blocks);
1273                      j++) {
1274                         BUG_ON((j + last_slot) >= reg->hr_blocks);
1275
1276                         slot = &reg->hr_slots[j + last_slot];
1277                         slot->ds_raw_block =
1278                                 (struct o2hb_disk_heartbeat_block *) raw;
1279
1280                         raw += reg->hr_block_bytes;
1281                 }
1282         }
1283
1284         return 0;
1285 }
1286
1287 /* Read in all the slots available and populate the tracking
1288  * structures so that we can start with a baseline idea of what's
1289  * there. */
1290 static int o2hb_populate_slot_data(struct o2hb_region *reg)
1291 {
1292         int ret, i;
1293         struct o2hb_disk_slot *slot;
1294         struct o2hb_disk_heartbeat_block *hb_block;
1295
1296         mlog_entry_void();
1297
1298         ret = o2hb_read_slots(reg, reg->hr_blocks);
1299         if (ret) {
1300                 mlog_errno(ret);
1301                 goto out;
1302         }
1303
1304         /* We only want to get an idea of the values initially in each
1305          * slot, so we do no verification - o2hb_check_slot will
1306          * actually determine if each configured slot is valid and
1307          * whether any values have changed. */
1308         for(i = 0; i < reg->hr_blocks; i++) {
1309                 slot = &reg->hr_slots[i];
1310                 hb_block = (struct o2hb_disk_heartbeat_block *) slot->ds_raw_block;
1311
1312                 /* Only fill the values that o2hb_check_slot uses to
1313                  * determine changing slots */
1314                 slot->ds_last_time = le64_to_cpu(hb_block->hb_seq);
1315                 slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);
1316         }
1317
1318 out:
1319         mlog_exit(ret);
1320         return ret;
1321 }
1322
1323 /* this is acting as commit; we set up all of hr_bdev and hr_task or nothing */
1324 static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
1325                                      const char *page,
1326                                      size_t count)
1327 {
1328         struct task_struct *hb_task;
1329         long fd;
1330         int sectsize;
1331         char *p = (char *)page;
1332         struct file *filp = NULL;
1333         struct inode *inode = NULL;
1334         ssize_t ret = -EINVAL;
1335
1336         if (reg->hr_bdev)
1337                 goto out;
1338
1339         /* We can't heartbeat without having had our node number
1340          * configured yet. */
1341         if (o2nm_this_node() == O2NM_MAX_NODES)
1342                 goto out;
1343
1344         fd = simple_strtol(p, &p, 0);
1345         if (!p || (*p && (*p != '\n')))
1346                 goto out;
1347
1348         if (fd < 0 || fd >= INT_MAX)
1349                 goto out;
1350
1351         filp = fget(fd);
1352         if (filp == NULL)
1353                 goto out;
1354
1355         if (reg->hr_blocks == 0 || reg->hr_start_block == 0 ||
1356             reg->hr_block_bytes == 0)
1357                 goto out;
1358
1359         inode = igrab(filp->f_mapping->host);
1360         if (inode == NULL)
1361                 goto out;
1362
1363         if (!S_ISBLK(inode->i_mode))
1364                 goto out;
1365
1366         reg->hr_bdev = I_BDEV(filp->f_mapping->host);
1367         ret = blkdev_get(reg->hr_bdev, FMODE_WRITE | FMODE_READ);
1368         if (ret) {
1369                 reg->hr_bdev = NULL;
1370                 goto out;
1371         }
1372         inode = NULL;
1373
1374         bdevname(reg->hr_bdev, reg->hr_dev_name);
1375
1376         sectsize = bdev_logical_block_size(reg->hr_bdev);
1377         if (sectsize != reg->hr_block_bytes) {
1378                 mlog(ML_ERROR,
1379                      "blocksize %u incorrect for device, expected %d",
1380                      reg->hr_block_bytes, sectsize);
1381                 ret = -EINVAL;
1382                 goto out;
1383         }
1384
1385         o2hb_init_region_params(reg);
1386
1387         /* Generation of zero is invalid */
1388         do {
1389                 get_random_bytes(&reg->hr_generation,
1390                                  sizeof(reg->hr_generation));
1391         } while (reg->hr_generation == 0);
1392
1393         ret = o2hb_map_slot_data(reg);
1394         if (ret) {
1395                 mlog_errno(ret);
1396                 goto out;
1397         }
1398
1399         ret = o2hb_populate_slot_data(reg);
1400         if (ret) {
1401                 mlog_errno(ret);
1402                 goto out;
1403         }
1404
1405         INIT_DELAYED_WORK(&reg->hr_write_timeout_work, o2hb_write_timeout);
1406
1407         /*
1408          * A node is considered live after it has beat LIVE_THRESHOLD
1409          * times.  We're not steady until we've given them a chance
1410          * _after_ our first read.
1411          */
1412         atomic_set(&reg->hr_steady_iterations, O2HB_LIVE_THRESHOLD + 1);
1413
1414         hb_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
1415                               reg->hr_item.ci_name);
1416         if (IS_ERR(hb_task)) {
1417                 ret = PTR_ERR(hb_task);
1418                 mlog_errno(ret);
1419                 goto out;
1420         }
1421
1422         spin_lock(&o2hb_live_lock);
1423         reg->hr_task = hb_task;
1424         spin_unlock(&o2hb_live_lock);
1425
1426         ret = wait_event_interruptible(o2hb_steady_queue,
1427                                 atomic_read(&reg->hr_steady_iterations) == 0);
1428         if (ret) {
1429                 /* We got interrupted (hello ptrace!).  Clean up */
1430                 spin_lock(&o2hb_live_lock);
1431                 hb_task = reg->hr_task;
1432                 reg->hr_task = NULL;
1433                 spin_unlock(&o2hb_live_lock);
1434
1435                 if (hb_task)
1436                         kthread_stop(hb_task);
1437                 goto out;
1438         }
1439
1440         /* Ok, we were woken.  Make sure it wasn't by drop_item() */
1441         spin_lock(&o2hb_live_lock);
1442         hb_task = reg->hr_task;
1443         spin_unlock(&o2hb_live_lock);
1444
1445         if (hb_task)
1446                 ret = count;
1447         else
1448                 ret = -EIO;
1449
1450 out:
1451         if (filp)
1452                 fput(filp);
1453         if (inode)
1454                 iput(inode);
1455         if (ret < 0) {
1456                 if (reg->hr_bdev) {
1457                         blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
1458                         reg->hr_bdev = NULL;
1459                 }
1460         }
1461         return ret;
1462 }
1463
1464 static ssize_t o2hb_region_pid_read(struct o2hb_region *reg,
1465                                       char *page)
1466 {
1467         pid_t pid = 0;
1468
1469         spin_lock(&o2hb_live_lock);
1470         if (reg->hr_task)
1471                 pid = task_pid_nr(reg->hr_task);
1472         spin_unlock(&o2hb_live_lock);
1473
1474         if (!pid)
1475                 return 0;
1476
1477         return sprintf(page, "%u\n", pid);
1478 }
1479
1480 struct o2hb_region_attribute {
1481         struct configfs_attribute attr;
1482         ssize_t (*show)(struct o2hb_region *, char *);
1483         ssize_t (*store)(struct o2hb_region *, const char *, size_t);
1484 };
1485
1486 static struct o2hb_region_attribute o2hb_region_attr_block_bytes = {
1487         .attr   = { .ca_owner = THIS_MODULE,
1488                     .ca_name = "block_bytes",
1489                     .ca_mode = S_IRUGO | S_IWUSR },
1490         .show   = o2hb_region_block_bytes_read,
1491         .store  = o2hb_region_block_bytes_write,
1492 };
1493
1494 static struct o2hb_region_attribute o2hb_region_attr_start_block = {
1495         .attr   = { .ca_owner = THIS_MODULE,
1496                     .ca_name = "start_block",
1497                     .ca_mode = S_IRUGO | S_IWUSR },
1498         .show   = o2hb_region_start_block_read,
1499         .store  = o2hb_region_start_block_write,
1500 };
1501
1502 static struct o2hb_region_attribute o2hb_region_attr_blocks = {
1503         .attr   = { .ca_owner = THIS_MODULE,
1504                     .ca_name = "blocks",
1505                     .ca_mode = S_IRUGO | S_IWUSR },
1506         .show   = o2hb_region_blocks_read,
1507         .store  = o2hb_region_blocks_write,
1508 };
1509
1510 static struct o2hb_region_attribute o2hb_region_attr_dev = {
1511         .attr   = { .ca_owner = THIS_MODULE,
1512                     .ca_name = "dev",
1513                     .ca_mode = S_IRUGO | S_IWUSR },
1514         .show   = o2hb_region_dev_read,
1515         .store  = o2hb_region_dev_write,
1516 };
1517
1518 static struct o2hb_region_attribute o2hb_region_attr_pid = {
1519        .attr   = { .ca_owner = THIS_MODULE,
1520                    .ca_name = "pid",
1521                    .ca_mode = S_IRUGO | S_IRUSR },
1522        .show   = o2hb_region_pid_read,
1523 };
1524
1525 static struct configfs_attribute *o2hb_region_attrs[] = {
1526         &o2hb_region_attr_block_bytes.attr,
1527         &o2hb_region_attr_start_block.attr,
1528         &o2hb_region_attr_blocks.attr,
1529         &o2hb_region_attr_dev.attr,
1530         &o2hb_region_attr_pid.attr,
1531         NULL,
1532 };
1533
1534 static ssize_t o2hb_region_show(struct config_item *item,
1535                                 struct configfs_attribute *attr,
1536                                 char *page)
1537 {
1538         struct o2hb_region *reg = to_o2hb_region(item);
1539         struct o2hb_region_attribute *o2hb_region_attr =
1540                 container_of(attr, struct o2hb_region_attribute, attr);
1541         ssize_t ret = 0;
1542
1543         if (o2hb_region_attr->show)
1544                 ret = o2hb_region_attr->show(reg, page);
1545         return ret;
1546 }
1547
1548 static ssize_t o2hb_region_store(struct config_item *item,
1549                                  struct configfs_attribute *attr,
1550                                  const char *page, size_t count)
1551 {
1552         struct o2hb_region *reg = to_o2hb_region(item);
1553         struct o2hb_region_attribute *o2hb_region_attr =
1554                 container_of(attr, struct o2hb_region_attribute, attr);
1555         ssize_t ret = -EINVAL;
1556
1557         if (o2hb_region_attr->store)
1558                 ret = o2hb_region_attr->store(reg, page, count);
1559         return ret;
1560 }
1561
1562 static struct configfs_item_operations o2hb_region_item_ops = {
1563         .release                = o2hb_region_release,
1564         .show_attribute         = o2hb_region_show,
1565         .store_attribute        = o2hb_region_store,
1566 };
1567
1568 static struct config_item_type o2hb_region_type = {
1569         .ct_item_ops    = &o2hb_region_item_ops,
1570         .ct_attrs       = o2hb_region_attrs,
1571         .ct_owner       = THIS_MODULE,
1572 };
1573
1574 /* heartbeat set */
1575
1576 struct o2hb_heartbeat_group {
1577         struct config_group hs_group;
1578         /* some stuff? */
1579 };
1580
1581 static struct o2hb_heartbeat_group *to_o2hb_heartbeat_group(struct config_group *group)
1582 {
1583         return group ?
1584                 container_of(group, struct o2hb_heartbeat_group, hs_group)
1585                 : NULL;
1586 }
1587
1588 static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *group,
1589                                                           const char *name)
1590 {
1591         struct o2hb_region *reg = NULL;
1592
1593         reg = kzalloc(sizeof(struct o2hb_region), GFP_KERNEL);
1594         if (reg == NULL)
1595                 return ERR_PTR(-ENOMEM);
1596
1597         config_item_init_type_name(&reg->hr_item, name, &o2hb_region_type);
1598
1599         spin_lock(&o2hb_live_lock);
1600         list_add_tail(&reg->hr_all_item, &o2hb_all_regions);
1601         spin_unlock(&o2hb_live_lock);
1602
1603         return &reg->hr_item;
1604 }
1605
1606 static void o2hb_heartbeat_group_drop_item(struct config_group *group,
1607                                            struct config_item *item)
1608 {
1609         struct task_struct *hb_task;
1610         struct o2hb_region *reg = to_o2hb_region(item);
1611
1612         /* stop the thread when the user removes the region dir */
1613         spin_lock(&o2hb_live_lock);
1614         hb_task = reg->hr_task;
1615         reg->hr_task = NULL;
1616         spin_unlock(&o2hb_live_lock);
1617
1618         if (hb_task)
1619                 kthread_stop(hb_task);
1620
1621         /*
1622          * If we're racing a dev_write(), we need to wake them.  They will
1623          * check reg->hr_task
1624          */
1625         if (atomic_read(&reg->hr_steady_iterations) != 0) {
1626                 atomic_set(&reg->hr_steady_iterations, 0);
1627                 wake_up(&o2hb_steady_queue);
1628         }
1629
1630         config_item_put(item);
1631 }
1632
1633 struct o2hb_heartbeat_group_attribute {
1634         struct configfs_attribute attr;
1635         ssize_t (*show)(struct o2hb_heartbeat_group *, char *);
1636         ssize_t (*store)(struct o2hb_heartbeat_group *, const char *, size_t);
1637 };
1638
1639 static ssize_t o2hb_heartbeat_group_show(struct config_item *item,
1640                                          struct configfs_attribute *attr,
1641                                          char *page)
1642 {
1643         struct o2hb_heartbeat_group *reg = to_o2hb_heartbeat_group(to_config_group(item));
1644         struct o2hb_heartbeat_group_attribute *o2hb_heartbeat_group_attr =
1645                 container_of(attr, struct o2hb_heartbeat_group_attribute, attr);
1646         ssize_t ret = 0;
1647
1648         if (o2hb_heartbeat_group_attr->show)
1649                 ret = o2hb_heartbeat_group_attr->show(reg, page);
1650         return ret;
1651 }
1652
1653 static ssize_t o2hb_heartbeat_group_store(struct config_item *item,
1654                                           struct configfs_attribute *attr,
1655                                           const char *page, size_t count)
1656 {
1657         struct o2hb_heartbeat_group *reg = to_o2hb_heartbeat_group(to_config_group(item));
1658         struct o2hb_heartbeat_group_attribute *o2hb_heartbeat_group_attr =
1659                 container_of(attr, struct o2hb_heartbeat_group_attribute, attr);
1660         ssize_t ret = -EINVAL;
1661
1662         if (o2hb_heartbeat_group_attr->store)
1663                 ret = o2hb_heartbeat_group_attr->store(reg, page, count);
1664         return ret;
1665 }
1666
1667 static ssize_t o2hb_heartbeat_group_threshold_show(struct o2hb_heartbeat_group *group,
1668                                                      char *page)
1669 {
1670         return sprintf(page, "%u\n", o2hb_dead_threshold);
1671 }
1672
1673 static ssize_t o2hb_heartbeat_group_threshold_store(struct o2hb_heartbeat_group *group,
1674                                                     const char *page,
1675                                                     size_t count)
1676 {
1677         unsigned long tmp;
1678         char *p = (char *)page;
1679
1680         tmp = simple_strtoul(p, &p, 10);
1681         if (!p || (*p && (*p != '\n')))
1682                 return -EINVAL;
1683
1684         /* this will validate ranges for us. */
1685         o2hb_dead_threshold_set((unsigned int) tmp);
1686
1687         return count;
1688 }
1689
1690 static struct o2hb_heartbeat_group_attribute o2hb_heartbeat_group_attr_threshold = {
1691         .attr   = { .ca_owner = THIS_MODULE,
1692                     .ca_name = "dead_threshold",
1693                     .ca_mode = S_IRUGO | S_IWUSR },
1694         .show   = o2hb_heartbeat_group_threshold_show,
1695         .store  = o2hb_heartbeat_group_threshold_store,
1696 };
1697
1698 static struct configfs_attribute *o2hb_heartbeat_group_attrs[] = {
1699         &o2hb_heartbeat_group_attr_threshold.attr,
1700         NULL,
1701 };
1702
1703 static struct configfs_item_operations o2hb_hearbeat_group_item_ops = {
1704         .show_attribute         = o2hb_heartbeat_group_show,
1705         .store_attribute        = o2hb_heartbeat_group_store,
1706 };
1707
1708 static struct configfs_group_operations o2hb_heartbeat_group_group_ops = {
1709         .make_item      = o2hb_heartbeat_group_make_item,
1710         .drop_item      = o2hb_heartbeat_group_drop_item,
1711 };
1712
1713 static struct config_item_type o2hb_heartbeat_group_type = {
1714         .ct_group_ops   = &o2hb_heartbeat_group_group_ops,
1715         .ct_item_ops    = &o2hb_hearbeat_group_item_ops,
1716         .ct_attrs       = o2hb_heartbeat_group_attrs,
1717         .ct_owner       = THIS_MODULE,
1718 };
1719
1720 /* this is just here to avoid touching group in heartbeat.h which the
1721  * entire damn world #includes */
1722 struct config_group *o2hb_alloc_hb_set(void)
1723 {
1724         struct o2hb_heartbeat_group *hs = NULL;
1725         struct config_group *ret = NULL;
1726
1727         hs = kzalloc(sizeof(struct o2hb_heartbeat_group), GFP_KERNEL);
1728         if (hs == NULL)
1729                 goto out;
1730
1731         config_group_init_type_name(&hs->hs_group, "heartbeat",
1732                                     &o2hb_heartbeat_group_type);
1733
1734         ret = &hs->hs_group;
1735 out:
1736         if (ret == NULL)
1737                 kfree(hs);
1738         return ret;
1739 }
1740
1741 void o2hb_free_hb_set(struct config_group *group)
1742 {
1743         struct o2hb_heartbeat_group *hs = to_o2hb_heartbeat_group(group);
1744         kfree(hs);
1745 }
1746
1747 /* hb callback registration and issueing */
1748
1749 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type)
1750 {
1751         if (type == O2HB_NUM_CB)
1752                 return ERR_PTR(-EINVAL);
1753
1754         return &o2hb_callbacks[type];
1755 }
1756
1757 void o2hb_setup_callback(struct o2hb_callback_func *hc,
1758                          enum o2hb_callback_type type,
1759                          o2hb_cb_func *func,
1760                          void *data,
1761                          int priority)
1762 {
1763         INIT_LIST_HEAD(&hc->hc_item);
1764         hc->hc_func = func;
1765         hc->hc_data = data;
1766         hc->hc_priority = priority;
1767         hc->hc_type = type;
1768         hc->hc_magic = O2HB_CB_MAGIC;
1769 }
1770 EXPORT_SYMBOL_GPL(o2hb_setup_callback);
1771
1772 static struct o2hb_region *o2hb_find_region(const char *region_uuid)
1773 {
1774         struct o2hb_region *p, *reg = NULL;
1775
1776         assert_spin_locked(&o2hb_live_lock);
1777
1778         list_for_each_entry(p, &o2hb_all_regions, hr_all_item) {
1779                 if (!strcmp(region_uuid, config_item_name(&p->hr_item))) {
1780                         reg = p;
1781                         break;
1782                 }
1783         }
1784
1785         return reg;
1786 }
1787
1788 static int o2hb_region_get(const char *region_uuid)
1789 {
1790         int ret = 0;
1791         struct o2hb_region *reg;
1792
1793         spin_lock(&o2hb_live_lock);
1794
1795         reg = o2hb_find_region(region_uuid);
1796         if (!reg)
1797                 ret = -ENOENT;
1798         spin_unlock(&o2hb_live_lock);
1799
1800         if (ret)
1801                 goto out;
1802
1803         ret = o2nm_depend_this_node();
1804         if (ret)
1805                 goto out;
1806
1807         ret = o2nm_depend_item(&reg->hr_item);
1808         if (ret)
1809                 o2nm_undepend_this_node();
1810
1811 out:
1812         return ret;
1813 }
1814
1815 static void o2hb_region_put(const char *region_uuid)
1816 {
1817         struct o2hb_region *reg;
1818
1819         spin_lock(&o2hb_live_lock);
1820
1821         reg = o2hb_find_region(region_uuid);
1822
1823         spin_unlock(&o2hb_live_lock);
1824
1825         if (reg) {
1826                 o2nm_undepend_item(&reg->hr_item);
1827                 o2nm_undepend_this_node();
1828         }
1829 }
1830
1831 int o2hb_register_callback(const char *region_uuid,
1832                            struct o2hb_callback_func *hc)
1833 {
1834         struct o2hb_callback_func *tmp;
1835         struct list_head *iter;
1836         struct o2hb_callback *hbcall;
1837         int ret;
1838
1839         BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
1840         BUG_ON(!list_empty(&hc->hc_item));
1841
1842         hbcall = hbcall_from_type(hc->hc_type);
1843         if (IS_ERR(hbcall)) {
1844                 ret = PTR_ERR(hbcall);
1845                 goto out;
1846         }
1847
1848         if (region_uuid) {
1849                 ret = o2hb_region_get(region_uuid);
1850                 if (ret)
1851                         goto out;
1852         }
1853
1854         down_write(&o2hb_callback_sem);
1855
1856         list_for_each(iter, &hbcall->list) {
1857                 tmp = list_entry(iter, struct o2hb_callback_func, hc_item);
1858                 if (hc->hc_priority < tmp->hc_priority) {
1859                         list_add_tail(&hc->hc_item, iter);
1860                         break;
1861                 }
1862         }
1863         if (list_empty(&hc->hc_item))
1864                 list_add_tail(&hc->hc_item, &hbcall->list);
1865
1866         up_write(&o2hb_callback_sem);
1867         ret = 0;
1868 out:
1869         mlog(ML_HEARTBEAT, "returning %d on behalf of %p for funcs %p\n",
1870              ret, __builtin_return_address(0), hc);
1871         return ret;
1872 }
1873 EXPORT_SYMBOL_GPL(o2hb_register_callback);
1874
1875 void o2hb_unregister_callback(const char *region_uuid,
1876                               struct o2hb_callback_func *hc)
1877 {
1878         BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
1879
1880         mlog(ML_HEARTBEAT, "on behalf of %p for funcs %p\n",
1881              __builtin_return_address(0), hc);
1882
1883         /* XXX Can this happen _with_ a region reference? */
1884         if (list_empty(&hc->hc_item))
1885                 return;
1886
1887         if (region_uuid)
1888                 o2hb_region_put(region_uuid);
1889
1890         down_write(&o2hb_callback_sem);
1891
1892         list_del_init(&hc->hc_item);
1893
1894         up_write(&o2hb_callback_sem);
1895 }
1896 EXPORT_SYMBOL_GPL(o2hb_unregister_callback);
1897
1898 int o2hb_check_node_heartbeating(u8 node_num)
1899 {
1900         unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
1901
1902         o2hb_fill_node_map(testing_map, sizeof(testing_map));
1903         if (!test_bit(node_num, testing_map)) {
1904                 mlog(ML_HEARTBEAT,
1905                      "node (%u) does not have heartbeating enabled.\n",
1906                      node_num);
1907                 return 0;
1908         }
1909
1910         return 1;
1911 }
1912 EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating);
1913
1914 int o2hb_check_node_heartbeating_from_callback(u8 node_num)
1915 {
1916         unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
1917
1918         o2hb_fill_node_map_from_callback(testing_map, sizeof(testing_map));
1919         if (!test_bit(node_num, testing_map)) {
1920                 mlog(ML_HEARTBEAT,
1921                      "node (%u) does not have heartbeating enabled.\n",
1922                      node_num);
1923                 return 0;
1924         }
1925
1926         return 1;
1927 }
1928 EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating_from_callback);
1929
1930 /* Makes sure our local node is configured with a node number, and is
1931  * heartbeating. */
1932 int o2hb_check_local_node_heartbeating(void)
1933 {
1934         u8 node_num;
1935
1936         /* if this node was set then we have networking */
1937         node_num = o2nm_this_node();
1938         if (node_num == O2NM_MAX_NODES) {
1939                 mlog(ML_HEARTBEAT, "this node has not been configured.\n");
1940                 return 0;
1941         }
1942
1943         return o2hb_check_node_heartbeating(node_num);
1944 }
1945 EXPORT_SYMBOL_GPL(o2hb_check_local_node_heartbeating);
1946
1947 /*
1948  * this is just a hack until we get the plumbing which flips file systems
1949  * read only and drops the hb ref instead of killing the node dead.
1950  */
1951 void o2hb_stop_all_regions(void)
1952 {
1953         struct o2hb_region *reg;
1954
1955         mlog(ML_ERROR, "stopping heartbeat on all active regions.\n");
1956
1957         spin_lock(&o2hb_live_lock);
1958
1959         list_for_each_entry(reg, &o2hb_all_regions, hr_all_item)
1960                 reg->hr_unclean_stop = 1;
1961
1962         spin_unlock(&o2hb_live_lock);
1963 }
1964 EXPORT_SYMBOL_GPL(o2hb_stop_all_regions);