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TOMOYO Linux Cross Reference
Linux/fs/ocfs2/cluster/heartbeat.c

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  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 #include <linux/slab.h>
 38 
 39 #include "heartbeat.h"
 40 #include "tcp.h"
 41 #include "nodemanager.h"
 42 #include "quorum.h"
 43 
 44 #include "masklog.h"
 45 
 46 
 47 /*
 48  * The first heartbeat pass had one global thread that would serialize all hb
 49  * callback calls.  This global serializing sem should only be removed once
 50  * we've made sure that all callees can deal with being called concurrently
 51  * from multiple hb region threads.
 52  */
 53 static DECLARE_RWSEM(o2hb_callback_sem);
 54 
 55 /*
 56  * multiple hb threads are watching multiple regions.  A node is live
 57  * whenever any of the threads sees activity from the node in its region.
 58  */
 59 static DEFINE_SPINLOCK(o2hb_live_lock);
 60 static struct list_head o2hb_live_slots[O2NM_MAX_NODES];
 61 static unsigned long o2hb_live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
 62 static LIST_HEAD(o2hb_node_events);
 63 static DECLARE_WAIT_QUEUE_HEAD(o2hb_steady_queue);
 64 
 65 /*
 66  * In global heartbeat, we maintain a series of region bitmaps.
 67  *      - o2hb_region_bitmap allows us to limit the region number to max region.
 68  *      - o2hb_live_region_bitmap tracks live regions (seen steady iterations).
 69  *      - o2hb_quorum_region_bitmap tracks live regions that have seen all nodes
 70  *              heartbeat on it.
 71  *      - o2hb_failed_region_bitmap tracks the regions that have seen io timeouts.
 72  */
 73 static unsigned long o2hb_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 74 static unsigned long o2hb_live_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 75 static unsigned long o2hb_quorum_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 76 static unsigned long o2hb_failed_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 77 
 78 #define O2HB_DB_TYPE_LIVENODES          0
 79 #define O2HB_DB_TYPE_LIVEREGIONS        1
 80 #define O2HB_DB_TYPE_QUORUMREGIONS      2
 81 #define O2HB_DB_TYPE_FAILEDREGIONS      3
 82 #define O2HB_DB_TYPE_REGION_LIVENODES   4
 83 #define O2HB_DB_TYPE_REGION_NUMBER      5
 84 #define O2HB_DB_TYPE_REGION_ELAPSED_TIME        6
 85 #define O2HB_DB_TYPE_REGION_PINNED      7
 86 struct o2hb_debug_buf {
 87         int db_type;
 88         int db_size;
 89         int db_len;
 90         void *db_data;
 91 };
 92 
 93 static struct o2hb_debug_buf *o2hb_db_livenodes;
 94 static struct o2hb_debug_buf *o2hb_db_liveregions;
 95 static struct o2hb_debug_buf *o2hb_db_quorumregions;
 96 static struct o2hb_debug_buf *o2hb_db_failedregions;
 97 
 98 #define O2HB_DEBUG_DIR                  "o2hb"
 99 #define O2HB_DEBUG_LIVENODES            "livenodes"
100 #define O2HB_DEBUG_LIVEREGIONS          "live_regions"
101 #define O2HB_DEBUG_QUORUMREGIONS        "quorum_regions"
102 #define O2HB_DEBUG_FAILEDREGIONS        "failed_regions"
103 #define O2HB_DEBUG_REGION_NUMBER        "num"
104 #define O2HB_DEBUG_REGION_ELAPSED_TIME  "elapsed_time_in_ms"
105 #define O2HB_DEBUG_REGION_PINNED        "pinned"
106 
107 static struct dentry *o2hb_debug_dir;
108 static struct dentry *o2hb_debug_livenodes;
109 static struct dentry *o2hb_debug_liveregions;
110 static struct dentry *o2hb_debug_quorumregions;
111 static struct dentry *o2hb_debug_failedregions;
112 
113 static LIST_HEAD(o2hb_all_regions);
114 
115 static struct o2hb_callback {
116         struct list_head list;
117 } o2hb_callbacks[O2HB_NUM_CB];
118 
119 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type);
120 
121 #define O2HB_DEFAULT_BLOCK_BITS       9
122 
123 enum o2hb_heartbeat_modes {
124         O2HB_HEARTBEAT_LOCAL            = 0,
125         O2HB_HEARTBEAT_GLOBAL,
126         O2HB_HEARTBEAT_NUM_MODES,
127 };
128 
129 char *o2hb_heartbeat_mode_desc[O2HB_HEARTBEAT_NUM_MODES] = {
130                 "local",        /* O2HB_HEARTBEAT_LOCAL */
131                 "global",       /* O2HB_HEARTBEAT_GLOBAL */
132 };
133 
134 unsigned int o2hb_dead_threshold = O2HB_DEFAULT_DEAD_THRESHOLD;
135 unsigned int o2hb_heartbeat_mode = O2HB_HEARTBEAT_LOCAL;
136 
137 /*
138  * o2hb_dependent_users tracks the number of registered callbacks that depend
139  * on heartbeat. o2net and o2dlm are two entities that register this callback.
140  * However only o2dlm depends on the heartbeat. It does not want the heartbeat
141  * to stop while a dlm domain is still active.
142  */
143 unsigned int o2hb_dependent_users;
144 
145 /*
146  * In global heartbeat mode, all regions are pinned if there are one or more
147  * dependent users and the quorum region count is <= O2HB_PIN_CUT_OFF. All
148  * regions are unpinned if the region count exceeds the cut off or the number
149  * of dependent users falls to zero.
150  */
151 #define O2HB_PIN_CUT_OFF                3
152 
153 /*
154  * In local heartbeat mode, we assume the dlm domain name to be the same as
155  * region uuid. This is true for domains created for the file system but not
156  * necessarily true for userdlm domains. This is a known limitation.
157  *
158  * In global heartbeat mode, we pin/unpin all o2hb regions. This solution
159  * works for both file system and userdlm domains.
160  */
161 static int o2hb_region_pin(const char *region_uuid);
162 static void o2hb_region_unpin(const char *region_uuid);
163 
164 /* Only sets a new threshold if there are no active regions.
165  *
166  * No locking or otherwise interesting code is required for reading
167  * o2hb_dead_threshold as it can't change once regions are active and
168  * it's not interesting to anyone until then anyway. */
169 static void o2hb_dead_threshold_set(unsigned int threshold)
170 {
171         if (threshold > O2HB_MIN_DEAD_THRESHOLD) {
172                 spin_lock(&o2hb_live_lock);
173                 if (list_empty(&o2hb_all_regions))
174                         o2hb_dead_threshold = threshold;
175                 spin_unlock(&o2hb_live_lock);
176         }
177 }
178 
179 static int o2hb_global_hearbeat_mode_set(unsigned int hb_mode)
180 {
181         int ret = -1;
182 
183         if (hb_mode < O2HB_HEARTBEAT_NUM_MODES) {
184                 spin_lock(&o2hb_live_lock);
185                 if (list_empty(&o2hb_all_regions)) {
186                         o2hb_heartbeat_mode = hb_mode;
187                         ret = 0;
188                 }
189                 spin_unlock(&o2hb_live_lock);
190         }
191 
192         return ret;
193 }
194 
195 struct o2hb_node_event {
196         struct list_head        hn_item;
197         enum o2hb_callback_type hn_event_type;
198         struct o2nm_node        *hn_node;
199         int                     hn_node_num;
200 };
201 
202 struct o2hb_disk_slot {
203         struct o2hb_disk_heartbeat_block *ds_raw_block;
204         u8                      ds_node_num;
205         u64                     ds_last_time;
206         u64                     ds_last_generation;
207         u16                     ds_equal_samples;
208         u16                     ds_changed_samples;
209         struct list_head        ds_live_item;
210 };
211 
212 /* each thread owns a region.. when we're asked to tear down the region
213  * we ask the thread to stop, who cleans up the region */
214 struct o2hb_region {
215         struct config_item      hr_item;
216 
217         struct list_head        hr_all_item;
218         unsigned                hr_unclean_stop:1,
219                                 hr_aborted_start:1,
220                                 hr_item_pinned:1,
221                                 hr_item_dropped:1;
222 
223         /* protected by the hr_callback_sem */
224         struct task_struct      *hr_task;
225 
226         unsigned int            hr_blocks;
227         unsigned long long      hr_start_block;
228 
229         unsigned int            hr_block_bits;
230         unsigned int            hr_block_bytes;
231 
232         unsigned int            hr_slots_per_page;
233         unsigned int            hr_num_pages;
234 
235         struct page             **hr_slot_data;
236         struct block_device     *hr_bdev;
237         struct o2hb_disk_slot   *hr_slots;
238 
239         /* live node map of this region */
240         unsigned long           hr_live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
241         unsigned int            hr_region_num;
242 
243         struct dentry           *hr_debug_dir;
244         struct dentry           *hr_debug_livenodes;
245         struct dentry           *hr_debug_regnum;
246         struct dentry           *hr_debug_elapsed_time;
247         struct dentry           *hr_debug_pinned;
248         struct o2hb_debug_buf   *hr_db_livenodes;
249         struct o2hb_debug_buf   *hr_db_regnum;
250         struct o2hb_debug_buf   *hr_db_elapsed_time;
251         struct o2hb_debug_buf   *hr_db_pinned;
252 
253         /* let the person setting up hb wait for it to return until it
254          * has reached a 'steady' state.  This will be fixed when we have
255          * a more complete api that doesn't lead to this sort of fragility. */
256         atomic_t                hr_steady_iterations;
257 
258         /* terminate o2hb thread if it does not reach steady state
259          * (hr_steady_iterations == 0) within hr_unsteady_iterations */
260         atomic_t                hr_unsteady_iterations;
261 
262         char                    hr_dev_name[BDEVNAME_SIZE];
263 
264         unsigned int            hr_timeout_ms;
265 
266         /* randomized as the region goes up and down so that a node
267          * recognizes a node going up and down in one iteration */
268         u64                     hr_generation;
269 
270         struct delayed_work     hr_write_timeout_work;
271         unsigned long           hr_last_timeout_start;
272 
273         /* Used during o2hb_check_slot to hold a copy of the block
274          * being checked because we temporarily have to zero out the
275          * crc field. */
276         struct o2hb_disk_heartbeat_block *hr_tmp_block;
277 };
278 
279 struct o2hb_bio_wait_ctxt {
280         atomic_t          wc_num_reqs;
281         struct completion wc_io_complete;
282         int               wc_error;
283 };
284 
285 static int o2hb_pop_count(void *map, int count)
286 {
287         int i = -1, pop = 0;
288 
289         while ((i = find_next_bit(map, count, i + 1)) < count)
290                 pop++;
291         return pop;
292 }
293 
294 static void o2hb_write_timeout(struct work_struct *work)
295 {
296         int failed, quorum;
297         unsigned long flags;
298         struct o2hb_region *reg =
299                 container_of(work, struct o2hb_region,
300                              hr_write_timeout_work.work);
301 
302         mlog(ML_ERROR, "Heartbeat write timeout to device %s after %u "
303              "milliseconds\n", reg->hr_dev_name,
304              jiffies_to_msecs(jiffies - reg->hr_last_timeout_start));
305 
306         if (o2hb_global_heartbeat_active()) {
307                 spin_lock_irqsave(&o2hb_live_lock, flags);
308                 if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
309                         set_bit(reg->hr_region_num, o2hb_failed_region_bitmap);
310                 failed = o2hb_pop_count(&o2hb_failed_region_bitmap,
311                                         O2NM_MAX_REGIONS);
312                 quorum = o2hb_pop_count(&o2hb_quorum_region_bitmap,
313                                         O2NM_MAX_REGIONS);
314                 spin_unlock_irqrestore(&o2hb_live_lock, flags);
315 
316                 mlog(ML_HEARTBEAT, "Number of regions %d, failed regions %d\n",
317                      quorum, failed);
318 
319                 /*
320                  * Fence if the number of failed regions >= half the number
321                  * of  quorum regions
322                  */
323                 if ((failed << 1) < quorum)
324                         return;
325         }
326 
327         o2quo_disk_timeout();
328 }
329 
330 static void o2hb_arm_write_timeout(struct o2hb_region *reg)
331 {
332         /* Arm writeout only after thread reaches steady state */
333         if (atomic_read(&reg->hr_steady_iterations) != 0)
334                 return;
335 
336         mlog(ML_HEARTBEAT, "Queue write timeout for %u ms\n",
337              O2HB_MAX_WRITE_TIMEOUT_MS);
338 
339         if (o2hb_global_heartbeat_active()) {
340                 spin_lock(&o2hb_live_lock);
341                 clear_bit(reg->hr_region_num, o2hb_failed_region_bitmap);
342                 spin_unlock(&o2hb_live_lock);
343         }
344         cancel_delayed_work(&reg->hr_write_timeout_work);
345         reg->hr_last_timeout_start = jiffies;
346         schedule_delayed_work(&reg->hr_write_timeout_work,
347                               msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS));
348 }
349 
350 static void o2hb_disarm_write_timeout(struct o2hb_region *reg)
351 {
352         cancel_delayed_work_sync(&reg->hr_write_timeout_work);
353 }
354 
355 static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc)
356 {
357         atomic_set(&wc->wc_num_reqs, 1);
358         init_completion(&wc->wc_io_complete);
359         wc->wc_error = 0;
360 }
361 
362 /* Used in error paths too */
363 static inline void o2hb_bio_wait_dec(struct o2hb_bio_wait_ctxt *wc,
364                                      unsigned int num)
365 {
366         /* sadly atomic_sub_and_test() isn't available on all platforms.  The
367          * good news is that the fast path only completes one at a time */
368         while(num--) {
369                 if (atomic_dec_and_test(&wc->wc_num_reqs)) {
370                         BUG_ON(num > 0);
371                         complete(&wc->wc_io_complete);
372                 }
373         }
374 }
375 
376 static void o2hb_wait_on_io(struct o2hb_region *reg,
377                             struct o2hb_bio_wait_ctxt *wc)
378 {
379         o2hb_bio_wait_dec(wc, 1);
380         wait_for_completion(&wc->wc_io_complete);
381 }
382 
383 static void o2hb_bio_end_io(struct bio *bio,
384                            int error)
385 {
386         struct o2hb_bio_wait_ctxt *wc = bio->bi_private;
387 
388         if (error) {
389                 mlog(ML_ERROR, "IO Error %d\n", error);
390                 wc->wc_error = error;
391         }
392 
393         o2hb_bio_wait_dec(wc, 1);
394         bio_put(bio);
395 }
396 
397 /* Setup a Bio to cover I/O against num_slots slots starting at
398  * start_slot. */
399 static struct bio *o2hb_setup_one_bio(struct o2hb_region *reg,
400                                       struct o2hb_bio_wait_ctxt *wc,
401                                       unsigned int *current_slot,
402                                       unsigned int max_slots)
403 {
404         int len, current_page;
405         unsigned int vec_len, vec_start;
406         unsigned int bits = reg->hr_block_bits;
407         unsigned int spp = reg->hr_slots_per_page;
408         unsigned int cs = *current_slot;
409         struct bio *bio;
410         struct page *page;
411 
412         /* Testing has shown this allocation to take long enough under
413          * GFP_KERNEL that the local node can get fenced. It would be
414          * nicest if we could pre-allocate these bios and avoid this
415          * all together. */
416         bio = bio_alloc(GFP_ATOMIC, 16);
417         if (!bio) {
418                 mlog(ML_ERROR, "Could not alloc slots BIO!\n");
419                 bio = ERR_PTR(-ENOMEM);
420                 goto bail;
421         }
422 
423         /* Must put everything in 512 byte sectors for the bio... */
424         bio->bi_sector = (reg->hr_start_block + cs) << (bits - 9);
425         bio->bi_bdev = reg->hr_bdev;
426         bio->bi_private = wc;
427         bio->bi_end_io = o2hb_bio_end_io;
428 
429         vec_start = (cs << bits) % PAGE_CACHE_SIZE;
430         while(cs < max_slots) {
431                 current_page = cs / spp;
432                 page = reg->hr_slot_data[current_page];
433 
434                 vec_len = min(PAGE_CACHE_SIZE - vec_start,
435                               (max_slots-cs) * (PAGE_CACHE_SIZE/spp) );
436 
437                 mlog(ML_HB_BIO, "page %d, vec_len = %u, vec_start = %u\n",
438                      current_page, vec_len, vec_start);
439 
440                 len = bio_add_page(bio, page, vec_len, vec_start);
441                 if (len != vec_len) break;
442 
443                 cs += vec_len / (PAGE_CACHE_SIZE/spp);
444                 vec_start = 0;
445         }
446 
447 bail:
448         *current_slot = cs;
449         return bio;
450 }
451 
452 static int o2hb_read_slots(struct o2hb_region *reg,
453                            unsigned int max_slots)
454 {
455         unsigned int current_slot=0;
456         int status;
457         struct o2hb_bio_wait_ctxt wc;
458         struct bio *bio;
459 
460         o2hb_bio_wait_init(&wc);
461 
462         while(current_slot < max_slots) {
463                 bio = o2hb_setup_one_bio(reg, &wc, &current_slot, max_slots);
464                 if (IS_ERR(bio)) {
465                         status = PTR_ERR(bio);
466                         mlog_errno(status);
467                         goto bail_and_wait;
468                 }
469 
470                 atomic_inc(&wc.wc_num_reqs);
471                 submit_bio(READ, bio);
472         }
473 
474         status = 0;
475 
476 bail_and_wait:
477         o2hb_wait_on_io(reg, &wc);
478         if (wc.wc_error && !status)
479                 status = wc.wc_error;
480 
481         return status;
482 }
483 
484 static int o2hb_issue_node_write(struct o2hb_region *reg,
485                                  struct o2hb_bio_wait_ctxt *write_wc)
486 {
487         int status;
488         unsigned int slot;
489         struct bio *bio;
490 
491         o2hb_bio_wait_init(write_wc);
492 
493         slot = o2nm_this_node();
494 
495         bio = o2hb_setup_one_bio(reg, write_wc, &slot, slot+1);
496         if (IS_ERR(bio)) {
497                 status = PTR_ERR(bio);
498                 mlog_errno(status);
499                 goto bail;
500         }
501 
502         atomic_inc(&write_wc->wc_num_reqs);
503         submit_bio(WRITE, bio);
504 
505         status = 0;
506 bail:
507         return status;
508 }
509 
510 static u32 o2hb_compute_block_crc_le(struct o2hb_region *reg,
511                                      struct o2hb_disk_heartbeat_block *hb_block)
512 {
513         __le32 old_cksum;
514         u32 ret;
515 
516         /* We want to compute the block crc with a 0 value in the
517          * hb_cksum field. Save it off here and replace after the
518          * crc. */
519         old_cksum = hb_block->hb_cksum;
520         hb_block->hb_cksum = 0;
521 
522         ret = crc32_le(0, (unsigned char *) hb_block, reg->hr_block_bytes);
523 
524         hb_block->hb_cksum = old_cksum;
525 
526         return ret;
527 }
528 
529 static void o2hb_dump_slot(struct o2hb_disk_heartbeat_block *hb_block)
530 {
531         mlog(ML_ERROR, "Dump slot information: seq = 0x%llx, node = %u, "
532              "cksum = 0x%x, generation 0x%llx\n",
533              (long long)le64_to_cpu(hb_block->hb_seq),
534              hb_block->hb_node, le32_to_cpu(hb_block->hb_cksum),
535              (long long)le64_to_cpu(hb_block->hb_generation));
536 }
537 
538 static int o2hb_verify_crc(struct o2hb_region *reg,
539                            struct o2hb_disk_heartbeat_block *hb_block)
540 {
541         u32 read, computed;
542 
543         read = le32_to_cpu(hb_block->hb_cksum);
544         computed = o2hb_compute_block_crc_le(reg, hb_block);
545 
546         return read == computed;
547 }
548 
549 /*
550  * Compare the slot data with what we wrote in the last iteration.
551  * If the match fails, print an appropriate error message. This is to
552  * detect errors like... another node hearting on the same slot,
553  * flaky device that is losing writes, etc.
554  * Returns 1 if check succeeds, 0 otherwise.
555  */
556 static int o2hb_check_own_slot(struct o2hb_region *reg)
557 {
558         struct o2hb_disk_slot *slot;
559         struct o2hb_disk_heartbeat_block *hb_block;
560         char *errstr;
561 
562         slot = &reg->hr_slots[o2nm_this_node()];
563         /* Don't check on our 1st timestamp */
564         if (!slot->ds_last_time)
565                 return 0;
566 
567         hb_block = slot->ds_raw_block;
568         if (le64_to_cpu(hb_block->hb_seq) == slot->ds_last_time &&
569             le64_to_cpu(hb_block->hb_generation) == slot->ds_last_generation &&
570             hb_block->hb_node == slot->ds_node_num)
571                 return 1;
572 
573 #define ERRSTR1         "Another node is heartbeating on device"
574 #define ERRSTR2         "Heartbeat generation mismatch on device"
575 #define ERRSTR3         "Heartbeat sequence mismatch on device"
576 
577         if (hb_block->hb_node != slot->ds_node_num)
578                 errstr = ERRSTR1;
579         else if (le64_to_cpu(hb_block->hb_generation) !=
580                  slot->ds_last_generation)
581                 errstr = ERRSTR2;
582         else
583                 errstr = ERRSTR3;
584 
585         mlog(ML_ERROR, "%s (%s): expected(%u:0x%llx, 0x%llx), "
586              "ondisk(%u:0x%llx, 0x%llx)\n", errstr, reg->hr_dev_name,
587              slot->ds_node_num, (unsigned long long)slot->ds_last_generation,
588              (unsigned long long)slot->ds_last_time, hb_block->hb_node,
589              (unsigned long long)le64_to_cpu(hb_block->hb_generation),
590              (unsigned long long)le64_to_cpu(hb_block->hb_seq));
591 
592         return 0;
593 }
594 
595 static inline void o2hb_prepare_block(struct o2hb_region *reg,
596                                       u64 generation)
597 {
598         int node_num;
599         u64 cputime;
600         struct o2hb_disk_slot *slot;
601         struct o2hb_disk_heartbeat_block *hb_block;
602 
603         node_num = o2nm_this_node();
604         slot = &reg->hr_slots[node_num];
605 
606         hb_block = (struct o2hb_disk_heartbeat_block *)slot->ds_raw_block;
607         memset(hb_block, 0, reg->hr_block_bytes);
608         /* TODO: time stuff */
609         cputime = CURRENT_TIME.tv_sec;
610         if (!cputime)
611                 cputime = 1;
612 
613         hb_block->hb_seq = cpu_to_le64(cputime);
614         hb_block->hb_node = node_num;
615         hb_block->hb_generation = cpu_to_le64(generation);
616         hb_block->hb_dead_ms = cpu_to_le32(o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS);
617 
618         /* This step must always happen last! */
619         hb_block->hb_cksum = cpu_to_le32(o2hb_compute_block_crc_le(reg,
620                                                                    hb_block));
621 
622         mlog(ML_HB_BIO, "our node generation = 0x%llx, cksum = 0x%x\n",
623              (long long)generation,
624              le32_to_cpu(hb_block->hb_cksum));
625 }
626 
627 static void o2hb_fire_callbacks(struct o2hb_callback *hbcall,
628                                 struct o2nm_node *node,
629                                 int idx)
630 {
631         struct list_head *iter;
632         struct o2hb_callback_func *f;
633 
634         list_for_each(iter, &hbcall->list) {
635                 f = list_entry(iter, struct o2hb_callback_func, hc_item);
636                 mlog(ML_HEARTBEAT, "calling funcs %p\n", f);
637                 (f->hc_func)(node, idx, f->hc_data);
638         }
639 }
640 
641 /* Will run the list in order until we process the passed event */
642 static void o2hb_run_event_list(struct o2hb_node_event *queued_event)
643 {
644         int empty;
645         struct o2hb_callback *hbcall;
646         struct o2hb_node_event *event;
647 
648         spin_lock(&o2hb_live_lock);
649         empty = list_empty(&queued_event->hn_item);
650         spin_unlock(&o2hb_live_lock);
651         if (empty)
652                 return;
653 
654         /* Holding callback sem assures we don't alter the callback
655          * lists when doing this, and serializes ourselves with other
656          * processes wanting callbacks. */
657         down_write(&o2hb_callback_sem);
658 
659         spin_lock(&o2hb_live_lock);
660         while (!list_empty(&o2hb_node_events)
661                && !list_empty(&queued_event->hn_item)) {
662                 event = list_entry(o2hb_node_events.next,
663                                    struct o2hb_node_event,
664                                    hn_item);
665                 list_del_init(&event->hn_item);
666                 spin_unlock(&o2hb_live_lock);
667 
668                 mlog(ML_HEARTBEAT, "Node %s event for %d\n",
669                      event->hn_event_type == O2HB_NODE_UP_CB ? "UP" : "DOWN",
670                      event->hn_node_num);
671 
672                 hbcall = hbcall_from_type(event->hn_event_type);
673 
674                 /* We should *never* have gotten on to the list with a
675                  * bad type... This isn't something that we should try
676                  * to recover from. */
677                 BUG_ON(IS_ERR(hbcall));
678 
679                 o2hb_fire_callbacks(hbcall, event->hn_node, event->hn_node_num);
680 
681                 spin_lock(&o2hb_live_lock);
682         }
683         spin_unlock(&o2hb_live_lock);
684 
685         up_write(&o2hb_callback_sem);
686 }
687 
688 static void o2hb_queue_node_event(struct o2hb_node_event *event,
689                                   enum o2hb_callback_type type,
690                                   struct o2nm_node *node,
691                                   int node_num)
692 {
693         assert_spin_locked(&o2hb_live_lock);
694 
695         BUG_ON((!node) && (type != O2HB_NODE_DOWN_CB));
696 
697         event->hn_event_type = type;
698         event->hn_node = node;
699         event->hn_node_num = node_num;
700 
701         mlog(ML_HEARTBEAT, "Queue node %s event for node %d\n",
702              type == O2HB_NODE_UP_CB ? "UP" : "DOWN", node_num);
703 
704         list_add_tail(&event->hn_item, &o2hb_node_events);
705 }
706 
707 static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
708 {
709         struct o2hb_node_event event =
710                 { .hn_item = LIST_HEAD_INIT(event.hn_item), };
711         struct o2nm_node *node;
712 
713         node = o2nm_get_node_by_num(slot->ds_node_num);
714         if (!node)
715                 return;
716 
717         spin_lock(&o2hb_live_lock);
718         if (!list_empty(&slot->ds_live_item)) {
719                 mlog(ML_HEARTBEAT, "Shutdown, node %d leaves region\n",
720                      slot->ds_node_num);
721 
722                 list_del_init(&slot->ds_live_item);
723 
724                 if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
725                         clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);
726 
727                         o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
728                                               slot->ds_node_num);
729                 }
730         }
731         spin_unlock(&o2hb_live_lock);
732 
733         o2hb_run_event_list(&event);
734 
735         o2nm_node_put(node);
736 }
737 
738 static void o2hb_set_quorum_device(struct o2hb_region *reg)
739 {
740         if (!o2hb_global_heartbeat_active())
741                 return;
742 
743         /* Prevent race with o2hb_heartbeat_group_drop_item() */
744         if (kthread_should_stop())
745                 return;
746 
747         /* Tag region as quorum only after thread reaches steady state */
748         if (atomic_read(&reg->hr_steady_iterations) != 0)
749                 return;
750 
751         spin_lock(&o2hb_live_lock);
752 
753         if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
754                 goto unlock;
755 
756         /*
757          * A region can be added to the quorum only when it sees all
758          * live nodes heartbeat on it. In other words, the region has been
759          * added to all nodes.
760          */
761         if (memcmp(reg->hr_live_node_bitmap, o2hb_live_node_bitmap,
762                    sizeof(o2hb_live_node_bitmap)))
763                 goto unlock;
764 
765         printk(KERN_NOTICE "o2hb: Region %s (%s) is now a quorum device\n",
766                config_item_name(&reg->hr_item), reg->hr_dev_name);
767 
768         set_bit(reg->hr_region_num, o2hb_quorum_region_bitmap);
769 
770         /*
771          * If global heartbeat active, unpin all regions if the
772          * region count > CUT_OFF
773          */
774         if (o2hb_pop_count(&o2hb_quorum_region_bitmap,
775                            O2NM_MAX_REGIONS) > O2HB_PIN_CUT_OFF)
776                 o2hb_region_unpin(NULL);
777 unlock:
778         spin_unlock(&o2hb_live_lock);
779 }
780 
781 static int o2hb_check_slot(struct o2hb_region *reg,
782                            struct o2hb_disk_slot *slot)
783 {
784         int changed = 0, gen_changed = 0;
785         struct o2hb_node_event event =
786                 { .hn_item = LIST_HEAD_INIT(event.hn_item), };
787         struct o2nm_node *node;
788         struct o2hb_disk_heartbeat_block *hb_block = reg->hr_tmp_block;
789         u64 cputime;
790         unsigned int dead_ms = o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS;
791         unsigned int slot_dead_ms;
792         int tmp;
793 
794         memcpy(hb_block, slot->ds_raw_block, reg->hr_block_bytes);
795 
796         /*
797          * If a node is no longer configured but is still in the livemap, we
798          * may need to clear that bit from the livemap.
799          */
800         node = o2nm_get_node_by_num(slot->ds_node_num);
801         if (!node) {
802                 spin_lock(&o2hb_live_lock);
803                 tmp = test_bit(slot->ds_node_num, o2hb_live_node_bitmap);
804                 spin_unlock(&o2hb_live_lock);
805                 if (!tmp)
806                         return 0;
807         }
808 
809         if (!o2hb_verify_crc(reg, hb_block)) {
810                 /* all paths from here will drop o2hb_live_lock for
811                  * us. */
812                 spin_lock(&o2hb_live_lock);
813 
814                 /* Don't print an error on the console in this case -
815                  * a freshly formatted heartbeat area will not have a
816                  * crc set on it. */
817                 if (list_empty(&slot->ds_live_item))
818                         goto out;
819 
820                 /* The node is live but pushed out a bad crc. We
821                  * consider it a transient miss but don't populate any
822                  * other values as they may be junk. */
823                 mlog(ML_ERROR, "Node %d has written a bad crc to %s\n",
824                      slot->ds_node_num, reg->hr_dev_name);
825                 o2hb_dump_slot(hb_block);
826 
827                 slot->ds_equal_samples++;
828                 goto fire_callbacks;
829         }
830 
831         /* we don't care if these wrap.. the state transitions below
832          * clear at the right places */
833         cputime = le64_to_cpu(hb_block->hb_seq);
834         if (slot->ds_last_time != cputime)
835                 slot->ds_changed_samples++;
836         else
837                 slot->ds_equal_samples++;
838         slot->ds_last_time = cputime;
839 
840         /* The node changed heartbeat generations. We assume this to
841          * mean it dropped off but came back before we timed out. We
842          * want to consider it down for the time being but don't want
843          * to lose any changed_samples state we might build up to
844          * considering it live again. */
845         if (slot->ds_last_generation != le64_to_cpu(hb_block->hb_generation)) {
846                 gen_changed = 1;
847                 slot->ds_equal_samples = 0;
848                 mlog(ML_HEARTBEAT, "Node %d changed generation (0x%llx "
849                      "to 0x%llx)\n", slot->ds_node_num,
850                      (long long)slot->ds_last_generation,
851                      (long long)le64_to_cpu(hb_block->hb_generation));
852         }
853 
854         slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);
855 
856         mlog(ML_HEARTBEAT, "Slot %d gen 0x%llx cksum 0x%x "
857              "seq %llu last %llu changed %u equal %u\n",
858              slot->ds_node_num, (long long)slot->ds_last_generation,
859              le32_to_cpu(hb_block->hb_cksum),
860              (unsigned long long)le64_to_cpu(hb_block->hb_seq),
861              (unsigned long long)slot->ds_last_time, slot->ds_changed_samples,
862              slot->ds_equal_samples);
863 
864         spin_lock(&o2hb_live_lock);
865 
866 fire_callbacks:
867         /* dead nodes only come to life after some number of
868          * changes at any time during their dead time */
869         if (list_empty(&slot->ds_live_item) &&
870             slot->ds_changed_samples >= O2HB_LIVE_THRESHOLD) {
871                 mlog(ML_HEARTBEAT, "Node %d (id 0x%llx) joined my region\n",
872                      slot->ds_node_num, (long long)slot->ds_last_generation);
873 
874                 set_bit(slot->ds_node_num, reg->hr_live_node_bitmap);
875 
876                 /* first on the list generates a callback */
877                 if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
878                         mlog(ML_HEARTBEAT, "o2hb: Add node %d to live nodes "
879                              "bitmap\n", slot->ds_node_num);
880                         set_bit(slot->ds_node_num, o2hb_live_node_bitmap);
881 
882                         o2hb_queue_node_event(&event, O2HB_NODE_UP_CB, node,
883                                               slot->ds_node_num);
884 
885                         changed = 1;
886                 }
887 
888                 list_add_tail(&slot->ds_live_item,
889                               &o2hb_live_slots[slot->ds_node_num]);
890 
891                 slot->ds_equal_samples = 0;
892 
893                 /* We want to be sure that all nodes agree on the
894                  * number of milliseconds before a node will be
895                  * considered dead. The self-fencing timeout is
896                  * computed from this value, and a discrepancy might
897                  * result in heartbeat calling a node dead when it
898                  * hasn't self-fenced yet. */
899                 slot_dead_ms = le32_to_cpu(hb_block->hb_dead_ms);
900                 if (slot_dead_ms && slot_dead_ms != dead_ms) {
901                         /* TODO: Perhaps we can fail the region here. */
902                         mlog(ML_ERROR, "Node %d on device %s has a dead count "
903                              "of %u ms, but our count is %u ms.\n"
904                              "Please double check your configuration values "
905                              "for 'O2CB_HEARTBEAT_THRESHOLD'\n",
906                              slot->ds_node_num, reg->hr_dev_name, slot_dead_ms,
907                              dead_ms);
908                 }
909                 goto out;
910         }
911 
912         /* if the list is dead, we're done.. */
913         if (list_empty(&slot->ds_live_item))
914                 goto out;
915 
916         /* live nodes only go dead after enough consequtive missed
917          * samples..  reset the missed counter whenever we see
918          * activity */
919         if (slot->ds_equal_samples >= o2hb_dead_threshold || gen_changed) {
920                 mlog(ML_HEARTBEAT, "Node %d left my region\n",
921                      slot->ds_node_num);
922 
923                 clear_bit(slot->ds_node_num, reg->hr_live_node_bitmap);
924 
925                 /* last off the live_slot generates a callback */
926                 list_del_init(&slot->ds_live_item);
927                 if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
928                         mlog(ML_HEARTBEAT, "o2hb: Remove node %d from live "
929                              "nodes bitmap\n", slot->ds_node_num);
930                         clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);
931 
932                         /* node can be null */
933                         o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB,
934                                               node, slot->ds_node_num);
935 
936                         changed = 1;
937                 }
938 
939                 /* We don't clear this because the node is still
940                  * actually writing new blocks. */
941                 if (!gen_changed)
942                         slot->ds_changed_samples = 0;
943                 goto out;
944         }
945         if (slot->ds_changed_samples) {
946                 slot->ds_changed_samples = 0;
947                 slot->ds_equal_samples = 0;
948         }
949 out:
950         spin_unlock(&o2hb_live_lock);
951 
952         o2hb_run_event_list(&event);
953 
954         if (node)
955                 o2nm_node_put(node);
956         return changed;
957 }
958 
959 /* This could be faster if we just implmented a find_last_bit, but I
960  * don't think the circumstances warrant it. */
961 static int o2hb_highest_node(unsigned long *nodes,
962                              int numbits)
963 {
964         int highest, node;
965 
966         highest = numbits;
967         node = -1;
968         while ((node = find_next_bit(nodes, numbits, node + 1)) != -1) {
969                 if (node >= numbits)
970                         break;
971 
972                 highest = node;
973         }
974 
975         return highest;
976 }
977 
978 static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
979 {
980         int i, ret, highest_node;
981         int membership_change = 0, own_slot_ok = 0;
982         unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
983         unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
984         struct o2hb_bio_wait_ctxt write_wc;
985 
986         ret = o2nm_configured_node_map(configured_nodes,
987                                        sizeof(configured_nodes));
988         if (ret) {
989                 mlog_errno(ret);
990                 goto bail;
991         }
992 
993         /*
994          * If a node is not configured but is in the livemap, we still need
995          * to read the slot so as to be able to remove it from the livemap.
996          */
997         o2hb_fill_node_map(live_node_bitmap, sizeof(live_node_bitmap));
998         i = -1;
999         while ((i = find_next_bit(live_node_bitmap,
1000                                   O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
1001                 set_bit(i, configured_nodes);
1002         }
1003 
1004         highest_node = o2hb_highest_node(configured_nodes, O2NM_MAX_NODES);
1005         if (highest_node >= O2NM_MAX_NODES) {
1006                 mlog(ML_NOTICE, "o2hb: No configured nodes found!\n");
1007                 ret = -EINVAL;
1008                 goto bail;
1009         }
1010 
1011         /* No sense in reading the slots of nodes that don't exist
1012          * yet. Of course, if the node definitions have holes in them
1013          * then we're reading an empty slot anyway... Consider this
1014          * best-effort. */
1015         ret = o2hb_read_slots(reg, highest_node + 1);
1016         if (ret < 0) {
1017                 mlog_errno(ret);
1018                 goto bail;
1019         }
1020 
1021         /* With an up to date view of the slots, we can check that no
1022          * other node has been improperly configured to heartbeat in
1023          * our slot. */
1024         own_slot_ok = o2hb_check_own_slot(reg);
1025 
1026         /* fill in the proper info for our next heartbeat */
1027         o2hb_prepare_block(reg, reg->hr_generation);
1028 
1029         ret = o2hb_issue_node_write(reg, &write_wc);
1030         if (ret < 0) {
1031                 mlog_errno(ret);
1032                 goto bail;
1033         }
1034 
1035         i = -1;
1036         while((i = find_next_bit(configured_nodes,
1037                                  O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
1038                 membership_change |= o2hb_check_slot(reg, &reg->hr_slots[i]);
1039         }
1040 
1041         /*
1042          * We have to be sure we've advertised ourselves on disk
1043          * before we can go to steady state.  This ensures that
1044          * people we find in our steady state have seen us.
1045          */
1046         o2hb_wait_on_io(reg, &write_wc);
1047         if (write_wc.wc_error) {
1048                 /* Do not re-arm the write timeout on I/O error - we
1049                  * can't be sure that the new block ever made it to
1050                  * disk */
1051                 mlog(ML_ERROR, "Write error %d on device \"%s\"\n",
1052                      write_wc.wc_error, reg->hr_dev_name);
1053                 ret = write_wc.wc_error;
1054                 goto bail;
1055         }
1056 
1057         /* Skip disarming the timeout if own slot has stale/bad data */
1058         if (own_slot_ok) {
1059                 o2hb_set_quorum_device(reg);
1060                 o2hb_arm_write_timeout(reg);
1061         }
1062 
1063 bail:
1064         /* let the person who launched us know when things are steady */
1065         if (atomic_read(&reg->hr_steady_iterations) != 0) {
1066                 if (!ret && own_slot_ok && !membership_change) {
1067                         if (atomic_dec_and_test(&reg->hr_steady_iterations))
1068                                 wake_up(&o2hb_steady_queue);
1069                 }
1070         }
1071 
1072         if (atomic_read(&reg->hr_steady_iterations) != 0) {
1073                 if (atomic_dec_and_test(&reg->hr_unsteady_iterations)) {
1074                         printk(KERN_NOTICE "o2hb: Unable to stabilize "
1075                                "heartbeart on region %s (%s)\n",
1076                                config_item_name(&reg->hr_item),
1077                                reg->hr_dev_name);
1078                         atomic_set(&reg->hr_steady_iterations, 0);
1079                         reg->hr_aborted_start = 1;
1080                         wake_up(&o2hb_steady_queue);
1081                         ret = -EIO;
1082                 }
1083         }
1084 
1085         return ret;
1086 }
1087 
1088 /* Subtract b from a, storing the result in a. a *must* have a larger
1089  * value than b. */
1090 static void o2hb_tv_subtract(struct timeval *a,
1091                              struct timeval *b)
1092 {
1093         /* just return 0 when a is after b */
1094         if (a->tv_sec < b->tv_sec ||
1095             (a->tv_sec == b->tv_sec && a->tv_usec < b->tv_usec)) {
1096                 a->tv_sec = 0;
1097                 a->tv_usec = 0;
1098                 return;
1099         }
1100 
1101         a->tv_sec -= b->tv_sec;
1102         a->tv_usec -= b->tv_usec;
1103         while ( a->tv_usec < 0 ) {
1104                 a->tv_sec--;
1105                 a->tv_usec += 1000000;
1106         }
1107 }
1108 
1109 static unsigned int o2hb_elapsed_msecs(struct timeval *start,
1110                                        struct timeval *end)
1111 {
1112         struct timeval res = *end;
1113 
1114         o2hb_tv_subtract(&res, start);
1115 
1116         return res.tv_sec * 1000 + res.tv_usec / 1000;
1117 }
1118 
1119 /*
1120  * we ride the region ref that the region dir holds.  before the region
1121  * dir is removed and drops it ref it will wait to tear down this
1122  * thread.
1123  */
1124 static int o2hb_thread(void *data)
1125 {
1126         int i, ret;
1127         struct o2hb_region *reg = data;
1128         struct o2hb_bio_wait_ctxt write_wc;
1129         struct timeval before_hb, after_hb;
1130         unsigned int elapsed_msec;
1131 
1132         mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread running\n");
1133 
1134         set_user_nice(current, -20);
1135 
1136         /* Pin node */
1137         o2nm_depend_this_node();
1138 
1139         while (!kthread_should_stop() &&
1140                !reg->hr_unclean_stop && !reg->hr_aborted_start) {
1141                 /* We track the time spent inside
1142                  * o2hb_do_disk_heartbeat so that we avoid more than
1143                  * hr_timeout_ms between disk writes. On busy systems
1144                  * this should result in a heartbeat which is less
1145                  * likely to time itself out. */
1146                 do_gettimeofday(&before_hb);
1147 
1148                 ret = o2hb_do_disk_heartbeat(reg);
1149 
1150                 do_gettimeofday(&after_hb);
1151                 elapsed_msec = o2hb_elapsed_msecs(&before_hb, &after_hb);
1152 
1153                 mlog(ML_HEARTBEAT,
1154                      "start = %lu.%lu, end = %lu.%lu, msec = %u\n",
1155                      before_hb.tv_sec, (unsigned long) before_hb.tv_usec,
1156                      after_hb.tv_sec, (unsigned long) after_hb.tv_usec,
1157                      elapsed_msec);
1158 
1159                 if (!kthread_should_stop() &&
1160                     elapsed_msec < reg->hr_timeout_ms) {
1161                         /* the kthread api has blocked signals for us so no
1162                          * need to record the return value. */
1163                         msleep_interruptible(reg->hr_timeout_ms - elapsed_msec);
1164                 }
1165         }
1166 
1167         o2hb_disarm_write_timeout(reg);
1168 
1169         /* unclean stop is only used in very bad situation */
1170         for(i = 0; !reg->hr_unclean_stop && i < reg->hr_blocks; i++)
1171                 o2hb_shutdown_slot(&reg->hr_slots[i]);
1172 
1173         /* Explicit down notification - avoid forcing the other nodes
1174          * to timeout on this region when we could just as easily
1175          * write a clear generation - thus indicating to them that
1176          * this node has left this region.
1177          */
1178         if (!reg->hr_unclean_stop && !reg->hr_aborted_start) {
1179                 o2hb_prepare_block(reg, 0);
1180                 ret = o2hb_issue_node_write(reg, &write_wc);
1181                 if (ret == 0)
1182                         o2hb_wait_on_io(reg, &write_wc);
1183                 else
1184                         mlog_errno(ret);
1185         }
1186 
1187         /* Unpin node */
1188         o2nm_undepend_this_node();
1189 
1190         mlog(ML_HEARTBEAT|ML_KTHREAD, "o2hb thread exiting\n");
1191 
1192         return 0;
1193 }
1194 
1195 #ifdef CONFIG_DEBUG_FS
1196 static int o2hb_debug_open(struct inode *inode, struct file *file)
1197 {
1198         struct o2hb_debug_buf *db = inode->i_private;
1199         struct o2hb_region *reg;
1200         unsigned long map[BITS_TO_LONGS(O2NM_MAX_NODES)];
1201         unsigned long lts;
1202         char *buf = NULL;
1203         int i = -1;
1204         int out = 0;
1205 
1206         /* max_nodes should be the largest bitmap we pass here */
1207         BUG_ON(sizeof(map) < db->db_size);
1208 
1209         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1210         if (!buf)
1211                 goto bail;
1212 
1213         switch (db->db_type) {
1214         case O2HB_DB_TYPE_LIVENODES:
1215         case O2HB_DB_TYPE_LIVEREGIONS:
1216         case O2HB_DB_TYPE_QUORUMREGIONS:
1217         case O2HB_DB_TYPE_FAILEDREGIONS:
1218                 spin_lock(&o2hb_live_lock);
1219                 memcpy(map, db->db_data, db->db_size);
1220                 spin_unlock(&o2hb_live_lock);
1221                 break;
1222 
1223         case O2HB_DB_TYPE_REGION_LIVENODES:
1224                 spin_lock(&o2hb_live_lock);
1225                 reg = (struct o2hb_region *)db->db_data;
1226                 memcpy(map, reg->hr_live_node_bitmap, db->db_size);
1227                 spin_unlock(&o2hb_live_lock);
1228                 break;
1229 
1230         case O2HB_DB_TYPE_REGION_NUMBER:
1231                 reg = (struct o2hb_region *)db->db_data;
1232                 out += snprintf(buf + out, PAGE_SIZE - out, "%d\n",
1233                                 reg->hr_region_num);
1234                 goto done;
1235 
1236         case O2HB_DB_TYPE_REGION_ELAPSED_TIME:
1237                 reg = (struct o2hb_region *)db->db_data;
1238                 lts = reg->hr_last_timeout_start;
1239                 /* If 0, it has never been set before */
1240                 if (lts)
1241                         lts = jiffies_to_msecs(jiffies - lts);
1242                 out += snprintf(buf + out, PAGE_SIZE - out, "%lu\n", lts);
1243                 goto done;
1244 
1245         case O2HB_DB_TYPE_REGION_PINNED:
1246                 reg = (struct o2hb_region *)db->db_data;
1247                 out += snprintf(buf + out, PAGE_SIZE - out, "%u\n",
1248                                 !!reg->hr_item_pinned);
1249                 goto done;
1250 
1251         default:
1252                 goto done;
1253         }
1254 
1255         while ((i = find_next_bit(map, db->db_len, i + 1)) < db->db_len)
1256                 out += snprintf(buf + out, PAGE_SIZE - out, "%d ", i);
1257         out += snprintf(buf + out, PAGE_SIZE - out, "\n");
1258 
1259 done:
1260         i_size_write(inode, out);
1261 
1262         file->private_data = buf;
1263 
1264         return 0;
1265 bail:
1266         return -ENOMEM;
1267 }
1268 
1269 static int o2hb_debug_release(struct inode *inode, struct file *file)
1270 {
1271         kfree(file->private_data);
1272         return 0;
1273 }
1274 
1275 static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
1276                                  size_t nbytes, loff_t *ppos)
1277 {
1278         return simple_read_from_buffer(buf, nbytes, ppos, file->private_data,
1279                                        i_size_read(file->f_mapping->host));
1280 }
1281 #else
1282 static int o2hb_debug_open(struct inode *inode, struct file *file)
1283 {
1284         return 0;
1285 }
1286 static int o2hb_debug_release(struct inode *inode, struct file *file)
1287 {
1288         return 0;
1289 }
1290 static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
1291                                size_t nbytes, loff_t *ppos)
1292 {
1293         return 0;
1294 }
1295 #endif  /* CONFIG_DEBUG_FS */
1296 
1297 static const struct file_operations o2hb_debug_fops = {
1298         .open =         o2hb_debug_open,
1299         .release =      o2hb_debug_release,
1300         .read =         o2hb_debug_read,
1301         .llseek =       generic_file_llseek,
1302 };
1303 
1304 void o2hb_exit(void)
1305 {
1306         kfree(o2hb_db_livenodes);
1307         kfree(o2hb_db_liveregions);
1308         kfree(o2hb_db_quorumregions);
1309         kfree(o2hb_db_failedregions);
1310         debugfs_remove(o2hb_debug_failedregions);
1311         debugfs_remove(o2hb_debug_quorumregions);
1312         debugfs_remove(o2hb_debug_liveregions);
1313         debugfs_remove(o2hb_debug_livenodes);
1314         debugfs_remove(o2hb_debug_dir);
1315 }
1316 
1317 static struct dentry *o2hb_debug_create(const char *name, struct dentry *dir,
1318                                         struct o2hb_debug_buf **db, int db_len,
1319                                         int type, int size, int len, void *data)
1320 {
1321         *db = kmalloc(db_len, GFP_KERNEL);
1322         if (!*db)
1323                 return NULL;
1324 
1325         (*db)->db_type = type;
1326         (*db)->db_size = size;
1327         (*db)->db_len = len;
1328         (*db)->db_data = data;
1329 
1330         return debugfs_create_file(name, S_IFREG|S_IRUSR, dir, *db,
1331                                    &o2hb_debug_fops);
1332 }
1333 
1334 static int o2hb_debug_init(void)
1335 {
1336         int ret = -ENOMEM;
1337 
1338         o2hb_debug_dir = debugfs_create_dir(O2HB_DEBUG_DIR, NULL);
1339         if (!o2hb_debug_dir) {
1340                 mlog_errno(ret);
1341                 goto bail;
1342         }
1343 
1344         o2hb_debug_livenodes = o2hb_debug_create(O2HB_DEBUG_LIVENODES,
1345                                                  o2hb_debug_dir,
1346                                                  &o2hb_db_livenodes,
1347                                                  sizeof(*o2hb_db_livenodes),
1348                                                  O2HB_DB_TYPE_LIVENODES,
1349                                                  sizeof(o2hb_live_node_bitmap),
1350                                                  O2NM_MAX_NODES,
1351                                                  o2hb_live_node_bitmap);
1352         if (!o2hb_debug_livenodes) {
1353                 mlog_errno(ret);
1354                 goto bail;
1355         }
1356 
1357         o2hb_debug_liveregions = o2hb_debug_create(O2HB_DEBUG_LIVEREGIONS,
1358                                                    o2hb_debug_dir,
1359                                                    &o2hb_db_liveregions,
1360                                                    sizeof(*o2hb_db_liveregions),
1361                                                    O2HB_DB_TYPE_LIVEREGIONS,
1362                                                    sizeof(o2hb_live_region_bitmap),
1363                                                    O2NM_MAX_REGIONS,
1364                                                    o2hb_live_region_bitmap);
1365         if (!o2hb_debug_liveregions) {
1366                 mlog_errno(ret);
1367                 goto bail;
1368         }
1369 
1370         o2hb_debug_quorumregions =
1371                         o2hb_debug_create(O2HB_DEBUG_QUORUMREGIONS,
1372                                           o2hb_debug_dir,
1373                                           &o2hb_db_quorumregions,
1374                                           sizeof(*o2hb_db_quorumregions),
1375                                           O2HB_DB_TYPE_QUORUMREGIONS,
1376                                           sizeof(o2hb_quorum_region_bitmap),
1377                                           O2NM_MAX_REGIONS,
1378                                           o2hb_quorum_region_bitmap);
1379         if (!o2hb_debug_quorumregions) {
1380                 mlog_errno(ret);
1381                 goto bail;
1382         }
1383 
1384         o2hb_debug_failedregions =
1385                         o2hb_debug_create(O2HB_DEBUG_FAILEDREGIONS,
1386                                           o2hb_debug_dir,
1387                                           &o2hb_db_failedregions,
1388                                           sizeof(*o2hb_db_failedregions),
1389                                           O2HB_DB_TYPE_FAILEDREGIONS,
1390                                           sizeof(o2hb_failed_region_bitmap),
1391                                           O2NM_MAX_REGIONS,
1392                                           o2hb_failed_region_bitmap);
1393         if (!o2hb_debug_failedregions) {
1394                 mlog_errno(ret);
1395                 goto bail;
1396         }
1397 
1398         ret = 0;
1399 bail:
1400         if (ret)
1401                 o2hb_exit();
1402 
1403         return ret;
1404 }
1405 
1406 int o2hb_init(void)
1407 {
1408         int i;
1409 
1410         for (i = 0; i < ARRAY_SIZE(o2hb_callbacks); i++)
1411                 INIT_LIST_HEAD(&o2hb_callbacks[i].list);
1412 
1413         for (i = 0; i < ARRAY_SIZE(o2hb_live_slots); i++)
1414                 INIT_LIST_HEAD(&o2hb_live_slots[i]);
1415 
1416         INIT_LIST_HEAD(&o2hb_node_events);
1417 
1418         memset(o2hb_live_node_bitmap, 0, sizeof(o2hb_live_node_bitmap));
1419         memset(o2hb_region_bitmap, 0, sizeof(o2hb_region_bitmap));
1420         memset(o2hb_live_region_bitmap, 0, sizeof(o2hb_live_region_bitmap));
1421         memset(o2hb_quorum_region_bitmap, 0, sizeof(o2hb_quorum_region_bitmap));
1422         memset(o2hb_failed_region_bitmap, 0, sizeof(o2hb_failed_region_bitmap));
1423 
1424         o2hb_dependent_users = 0;
1425 
1426         return o2hb_debug_init();
1427 }
1428 
1429 /* if we're already in a callback then we're already serialized by the sem */
1430 static void o2hb_fill_node_map_from_callback(unsigned long *map,
1431                                              unsigned bytes)
1432 {
1433         BUG_ON(bytes < (BITS_TO_LONGS(O2NM_MAX_NODES) * sizeof(unsigned long)));
1434 
1435         memcpy(map, &o2hb_live_node_bitmap, bytes);
1436 }
1437 
1438 /*
1439  * get a map of all nodes that are heartbeating in any regions
1440  */
1441 void o2hb_fill_node_map(unsigned long *map, unsigned bytes)
1442 {
1443         /* callers want to serialize this map and callbacks so that they
1444          * can trust that they don't miss nodes coming to the party */
1445         down_read(&o2hb_callback_sem);
1446         spin_lock(&o2hb_live_lock);
1447         o2hb_fill_node_map_from_callback(map, bytes);
1448         spin_unlock(&o2hb_live_lock);
1449         up_read(&o2hb_callback_sem);
1450 }
1451 EXPORT_SYMBOL_GPL(o2hb_fill_node_map);
1452 
1453 /*
1454  * heartbeat configfs bits.  The heartbeat set is a default set under
1455  * the cluster set in nodemanager.c.
1456  */
1457 
1458 static struct o2hb_region *to_o2hb_region(struct config_item *item)
1459 {
1460         return item ? container_of(item, struct o2hb_region, hr_item) : NULL;
1461 }
1462 
1463 /* drop_item only drops its ref after killing the thread, nothing should
1464  * be using the region anymore.  this has to clean up any state that
1465  * attributes might have built up. */
1466 static void o2hb_region_release(struct config_item *item)
1467 {
1468         int i;
1469         struct page *page;
1470         struct o2hb_region *reg = to_o2hb_region(item);
1471 
1472         mlog(ML_HEARTBEAT, "hb region release (%s)\n", reg->hr_dev_name);
1473 
1474         kfree(reg->hr_tmp_block);
1475 
1476         if (reg->hr_slot_data) {
1477                 for (i = 0; i < reg->hr_num_pages; i++) {
1478                         page = reg->hr_slot_data[i];
1479                         if (page)
1480                                 __free_page(page);
1481                 }
1482                 kfree(reg->hr_slot_data);
1483         }
1484 
1485         if (reg->hr_bdev)
1486                 blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
1487 
1488         kfree(reg->hr_slots);
1489 
1490         kfree(reg->hr_db_regnum);
1491         kfree(reg->hr_db_livenodes);
1492         debugfs_remove(reg->hr_debug_livenodes);
1493         debugfs_remove(reg->hr_debug_regnum);
1494         debugfs_remove(reg->hr_debug_elapsed_time);
1495         debugfs_remove(reg->hr_debug_pinned);
1496         debugfs_remove(reg->hr_debug_dir);
1497 
1498         spin_lock(&o2hb_live_lock);
1499         list_del(&reg->hr_all_item);
1500         spin_unlock(&o2hb_live_lock);
1501 
1502         kfree(reg);
1503 }
1504 
1505 static int o2hb_read_block_input(struct o2hb_region *reg,
1506                                  const char *page,
1507                                  size_t count,
1508                                  unsigned long *ret_bytes,
1509                                  unsigned int *ret_bits)
1510 {
1511         unsigned long bytes;
1512         char *p = (char *)page;
1513 
1514         bytes = simple_strtoul(p, &p, 0);
1515         if (!p || (*p && (*p != '\n')))
1516                 return -EINVAL;
1517 
1518         /* Heartbeat and fs min / max block sizes are the same. */
1519         if (bytes > 4096 || bytes < 512)
1520                 return -ERANGE;
1521         if (hweight16(bytes) != 1)
1522                 return -EINVAL;
1523 
1524         if (ret_bytes)
1525                 *ret_bytes = bytes;
1526         if (ret_bits)
1527                 *ret_bits = ffs(bytes) - 1;
1528 
1529         return 0;
1530 }
1531 
1532 static ssize_t o2hb_region_block_bytes_read(struct o2hb_region *reg,
1533                                             char *page)
1534 {
1535         return sprintf(page, "%u\n", reg->hr_block_bytes);
1536 }
1537 
1538 static ssize_t o2hb_region_block_bytes_write(struct o2hb_region *reg,
1539                                              const char *page,
1540                                              size_t count)
1541 {
1542         int status;
1543         unsigned long block_bytes;
1544         unsigned int block_bits;
1545 
1546         if (reg->hr_bdev)
1547                 return -EINVAL;
1548 
1549         status = o2hb_read_block_input(reg, page, count,
1550                                        &block_bytes, &block_bits);
1551         if (status)
1552                 return status;
1553 
1554         reg->hr_block_bytes = (unsigned int)block_bytes;
1555         reg->hr_block_bits = block_bits;
1556 
1557         return count;
1558 }
1559 
1560 static ssize_t o2hb_region_start_block_read(struct o2hb_region *reg,
1561                                             char *page)
1562 {
1563         return sprintf(page, "%llu\n", reg->hr_start_block);
1564 }
1565 
1566 static ssize_t o2hb_region_start_block_write(struct o2hb_region *reg,
1567                                              const char *page,
1568                                              size_t count)
1569 {
1570         unsigned long long tmp;
1571         char *p = (char *)page;
1572 
1573         if (reg->hr_bdev)
1574                 return -EINVAL;
1575 
1576         tmp = simple_strtoull(p, &p, 0);
1577         if (!p || (*p && (*p != '\n')))
1578                 return -EINVAL;
1579 
1580         reg->hr_start_block = tmp;
1581 
1582         return count;
1583 }
1584 
1585 static ssize_t o2hb_region_blocks_read(struct o2hb_region *reg,
1586                                        char *page)
1587 {
1588         return sprintf(page, "%d\n", reg->hr_blocks);
1589 }
1590 
1591 static ssize_t o2hb_region_blocks_write(struct o2hb_region *reg,
1592                                         const char *page,
1593                                         size_t count)
1594 {
1595         unsigned long tmp;
1596         char *p = (char *)page;
1597 
1598         if (reg->hr_bdev)
1599                 return -EINVAL;
1600 
1601         tmp = simple_strtoul(p, &p, 0);
1602         if (!p || (*p && (*p != '\n')))
1603                 return -EINVAL;
1604 
1605         if (tmp > O2NM_MAX_NODES || tmp == 0)
1606                 return -ERANGE;
1607 
1608         reg->hr_blocks = (unsigned int)tmp;
1609 
1610         return count;
1611 }
1612 
1613 static ssize_t o2hb_region_dev_read(struct o2hb_region *reg,
1614                                     char *page)
1615 {
1616         unsigned int ret = 0;
1617 
1618         if (reg->hr_bdev)
1619                 ret = sprintf(page, "%s\n", reg->hr_dev_name);
1620 
1621         return ret;
1622 }
1623 
1624 static void o2hb_init_region_params(struct o2hb_region *reg)
1625 {
1626         reg->hr_slots_per_page = PAGE_CACHE_SIZE >> reg->hr_block_bits;
1627         reg->hr_timeout_ms = O2HB_REGION_TIMEOUT_MS;
1628 
1629         mlog(ML_HEARTBEAT, "hr_start_block = %llu, hr_blocks = %u\n",
1630              reg->hr_start_block, reg->hr_blocks);
1631         mlog(ML_HEARTBEAT, "hr_block_bytes = %u, hr_block_bits = %u\n",
1632              reg->hr_block_bytes, reg->hr_block_bits);
1633         mlog(ML_HEARTBEAT, "hr_timeout_ms = %u\n", reg->hr_timeout_ms);
1634         mlog(ML_HEARTBEAT, "dead threshold = %u\n", o2hb_dead_threshold);
1635 }
1636 
1637 static int o2hb_map_slot_data(struct o2hb_region *reg)
1638 {
1639         int i, j;
1640         unsigned int last_slot;
1641         unsigned int spp = reg->hr_slots_per_page;
1642         struct page *page;
1643         char *raw;
1644         struct o2hb_disk_slot *slot;
1645 
1646         reg->hr_tmp_block = kmalloc(reg->hr_block_bytes, GFP_KERNEL);
1647         if (reg->hr_tmp_block == NULL) {
1648                 mlog_errno(-ENOMEM);
1649                 return -ENOMEM;
1650         }
1651 
1652         reg->hr_slots = kcalloc(reg->hr_blocks,
1653                                 sizeof(struct o2hb_disk_slot), GFP_KERNEL);
1654         if (reg->hr_slots == NULL) {
1655                 mlog_errno(-ENOMEM);
1656                 return -ENOMEM;
1657         }
1658 
1659         for(i = 0; i < reg->hr_blocks; i++) {
1660                 slot = &reg->hr_slots[i];
1661                 slot->ds_node_num = i;
1662                 INIT_LIST_HEAD(&slot->ds_live_item);
1663                 slot->ds_raw_block = NULL;
1664         }
1665 
1666         reg->hr_num_pages = (reg->hr_blocks + spp - 1) / spp;
1667         mlog(ML_HEARTBEAT, "Going to require %u pages to cover %u blocks "
1668                            "at %u blocks per page\n",
1669              reg->hr_num_pages, reg->hr_blocks, spp);
1670 
1671         reg->hr_slot_data = kcalloc(reg->hr_num_pages, sizeof(struct page *),
1672                                     GFP_KERNEL);
1673         if (!reg->hr_slot_data) {
1674                 mlog_errno(-ENOMEM);
1675                 return -ENOMEM;
1676         }
1677 
1678         for(i = 0; i < reg->hr_num_pages; i++) {
1679                 page = alloc_page(GFP_KERNEL);
1680                 if (!page) {
1681                         mlog_errno(-ENOMEM);
1682                         return -ENOMEM;
1683                 }
1684 
1685                 reg->hr_slot_data[i] = page;
1686 
1687                 last_slot = i * spp;
1688                 raw = page_address(page);
1689                 for (j = 0;
1690                      (j < spp) && ((j + last_slot) < reg->hr_blocks);
1691                      j++) {
1692                         BUG_ON((j + last_slot) >= reg->hr_blocks);
1693 
1694                         slot = &reg->hr_slots[j + last_slot];
1695                         slot->ds_raw_block =
1696                                 (struct o2hb_disk_heartbeat_block *) raw;
1697 
1698                         raw += reg->hr_block_bytes;
1699                 }
1700         }
1701 
1702         return 0;
1703 }
1704 
1705 /* Read in all the slots available and populate the tracking
1706  * structures so that we can start with a baseline idea of what's
1707  * there. */
1708 static int o2hb_populate_slot_data(struct o2hb_region *reg)
1709 {
1710         int ret, i;
1711         struct o2hb_disk_slot *slot;
1712         struct o2hb_disk_heartbeat_block *hb_block;
1713 
1714         ret = o2hb_read_slots(reg, reg->hr_blocks);
1715         if (ret) {
1716                 mlog_errno(ret);
1717                 goto out;
1718         }
1719 
1720         /* We only want to get an idea of the values initially in each
1721          * slot, so we do no verification - o2hb_check_slot will
1722          * actually determine if each configured slot is valid and
1723          * whether any values have changed. */
1724         for(i = 0; i < reg->hr_blocks; i++) {
1725                 slot = &reg->hr_slots[i];
1726                 hb_block = (struct o2hb_disk_heartbeat_block *) slot->ds_raw_block;
1727 
1728                 /* Only fill the values that o2hb_check_slot uses to
1729                  * determine changing slots */
1730                 slot->ds_last_time = le64_to_cpu(hb_block->hb_seq);
1731                 slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);
1732         }
1733 
1734 out:
1735         return ret;
1736 }
1737 
1738 /* this is acting as commit; we set up all of hr_bdev and hr_task or nothing */
1739 static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
1740                                      const char *page,
1741                                      size_t count)
1742 {
1743         struct task_struct *hb_task;
1744         long fd;
1745         int sectsize;
1746         char *p = (char *)page;
1747         struct fd f;
1748         struct inode *inode;
1749         ssize_t ret = -EINVAL;
1750         int live_threshold;
1751 
1752         if (reg->hr_bdev)
1753                 goto out;
1754 
1755         /* We can't heartbeat without having had our node number
1756          * configured yet. */
1757         if (o2nm_this_node() == O2NM_MAX_NODES)
1758                 goto out;
1759 
1760         fd = simple_strtol(p, &p, 0);
1761         if (!p || (*p && (*p != '\n')))
1762                 goto out;
1763 
1764         if (fd < 0 || fd >= INT_MAX)
1765                 goto out;
1766 
1767         f = fdget(fd);
1768         if (f.file == NULL)
1769                 goto out;
1770 
1771         if (reg->hr_blocks == 0 || reg->hr_start_block == 0 ||
1772             reg->hr_block_bytes == 0)
1773                 goto out2;
1774 
1775         inode = igrab(f.file->f_mapping->host);
1776         if (inode == NULL)
1777                 goto out2;
1778 
1779         if (!S_ISBLK(inode->i_mode))
1780                 goto out3;
1781 
1782         reg->hr_bdev = I_BDEV(f.file->f_mapping->host);
1783         ret = blkdev_get(reg->hr_bdev, FMODE_WRITE | FMODE_READ, NULL);
1784         if (ret) {
1785                 reg->hr_bdev = NULL;
1786                 goto out3;
1787         }
1788         inode = NULL;
1789 
1790         bdevname(reg->hr_bdev, reg->hr_dev_name);
1791 
1792         sectsize = bdev_logical_block_size(reg->hr_bdev);
1793         if (sectsize != reg->hr_block_bytes) {
1794                 mlog(ML_ERROR,
1795                      "blocksize %u incorrect for device, expected %d",
1796                      reg->hr_block_bytes, sectsize);
1797                 ret = -EINVAL;
1798                 goto out3;
1799         }
1800 
1801         o2hb_init_region_params(reg);
1802 
1803         /* Generation of zero is invalid */
1804         do {
1805                 get_random_bytes(&reg->hr_generation,
1806                                  sizeof(reg->hr_generation));
1807         } while (reg->hr_generation == 0);
1808 
1809         ret = o2hb_map_slot_data(reg);
1810         if (ret) {
1811                 mlog_errno(ret);
1812                 goto out3;
1813         }
1814 
1815         ret = o2hb_populate_slot_data(reg);
1816         if (ret) {
1817                 mlog_errno(ret);
1818                 goto out3;
1819         }
1820 
1821         INIT_DELAYED_WORK(&reg->hr_write_timeout_work, o2hb_write_timeout);
1822 
1823         /*
1824          * A node is considered live after it has beat LIVE_THRESHOLD
1825          * times.  We're not steady until we've given them a chance
1826          * _after_ our first read.
1827          * The default threshold is bare minimum so as to limit the delay
1828          * during mounts. For global heartbeat, the threshold doubled for the
1829          * first region.
1830          */
1831         live_threshold = O2HB_LIVE_THRESHOLD;
1832         if (o2hb_global_heartbeat_active()) {
1833                 spin_lock(&o2hb_live_lock);
1834                 if (o2hb_pop_count(&o2hb_region_bitmap, O2NM_MAX_REGIONS) == 1)
1835                         live_threshold <<= 1;
1836                 spin_unlock(&o2hb_live_lock);
1837         }
1838         ++live_threshold;
1839         atomic_set(&reg->hr_steady_iterations, live_threshold);
1840         /* unsteady_iterations is double the steady_iterations */
1841         atomic_set(&reg->hr_unsteady_iterations, (live_threshold << 1));
1842 
1843         hb_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
1844                               reg->hr_item.ci_name);
1845         if (IS_ERR(hb_task)) {
1846                 ret = PTR_ERR(hb_task);
1847                 mlog_errno(ret);
1848                 goto out3;
1849         }
1850 
1851         spin_lock(&o2hb_live_lock);
1852         reg->hr_task = hb_task;
1853         spin_unlock(&o2hb_live_lock);
1854 
1855         ret = wait_event_interruptible(o2hb_steady_queue,
1856                                 atomic_read(&reg->hr_steady_iterations) == 0);
1857         if (ret) {
1858                 atomic_set(&reg->hr_steady_iterations, 0);
1859                 reg->hr_aborted_start = 1;
1860         }
1861 
1862         if (reg->hr_aborted_start) {
1863                 ret = -EIO;
1864                 goto out3;
1865         }
1866 
1867         /* Ok, we were woken.  Make sure it wasn't by drop_item() */
1868         spin_lock(&o2hb_live_lock);
1869         hb_task = reg->hr_task;
1870         if (o2hb_global_heartbeat_active())
1871                 set_bit(reg->hr_region_num, o2hb_live_region_bitmap);
1872         spin_unlock(&o2hb_live_lock);
1873 
1874         if (hb_task)
1875                 ret = count;
1876         else
1877                 ret = -EIO;
1878 
1879         if (hb_task && o2hb_global_heartbeat_active())
1880                 printk(KERN_NOTICE "o2hb: Heartbeat started on region %s (%s)\n",
1881                        config_item_name(&reg->hr_item), reg->hr_dev_name);
1882 
1883 out3:
1884         iput(inode);
1885 out2:
1886         fdput(f);
1887 out:
1888         if (ret < 0) {
1889                 if (reg->hr_bdev) {
1890                         blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
1891                         reg->hr_bdev = NULL;
1892                 }
1893         }
1894         return ret;
1895 }
1896 
1897 static ssize_t o2hb_region_pid_read(struct o2hb_region *reg,
1898                                       char *page)
1899 {
1900         pid_t pid = 0;
1901 
1902         spin_lock(&o2hb_live_lock);
1903         if (reg->hr_task)
1904                 pid = task_pid_nr(reg->hr_task);
1905         spin_unlock(&o2hb_live_lock);
1906 
1907         if (!pid)
1908                 return 0;
1909 
1910         return sprintf(page, "%u\n", pid);
1911 }
1912 
1913 struct o2hb_region_attribute {
1914         struct configfs_attribute attr;
1915         ssize_t (*show)(struct o2hb_region *, char *);
1916         ssize_t (*store)(struct o2hb_region *, const char *, size_t);
1917 };
1918 
1919 static struct o2hb_region_attribute o2hb_region_attr_block_bytes = {
1920         .attr   = { .ca_owner = THIS_MODULE,
1921                     .ca_name = "block_bytes",
1922                     .ca_mode = S_IRUGO | S_IWUSR },
1923         .show   = o2hb_region_block_bytes_read,
1924         .store  = o2hb_region_block_bytes_write,
1925 };
1926 
1927 static struct o2hb_region_attribute o2hb_region_attr_start_block = {
1928         .attr   = { .ca_owner = THIS_MODULE,
1929                     .ca_name = "start_block",
1930                     .ca_mode = S_IRUGO | S_IWUSR },
1931         .show   = o2hb_region_start_block_read,
1932         .store  = o2hb_region_start_block_write,
1933 };
1934 
1935 static struct o2hb_region_attribute o2hb_region_attr_blocks = {
1936         .attr   = { .ca_owner = THIS_MODULE,
1937                     .ca_name = "blocks",
1938                     .ca_mode = S_IRUGO | S_IWUSR },
1939         .show   = o2hb_region_blocks_read,
1940         .store  = o2hb_region_blocks_write,
1941 };
1942 
1943 static struct o2hb_region_attribute o2hb_region_attr_dev = {
1944         .attr   = { .ca_owner = THIS_MODULE,
1945                     .ca_name = "dev",
1946                     .ca_mode = S_IRUGO | S_IWUSR },
1947         .show   = o2hb_region_dev_read,
1948         .store  = o2hb_region_dev_write,
1949 };
1950 
1951 static struct o2hb_region_attribute o2hb_region_attr_pid = {
1952        .attr   = { .ca_owner = THIS_MODULE,
1953                    .ca_name = "pid",
1954                    .ca_mode = S_IRUGO | S_IRUSR },
1955        .show   = o2hb_region_pid_read,
1956 };
1957 
1958 static struct configfs_attribute *o2hb_region_attrs[] = {
1959         &o2hb_region_attr_block_bytes.attr,
1960         &o2hb_region_attr_start_block.attr,
1961         &o2hb_region_attr_blocks.attr,
1962         &o2hb_region_attr_dev.attr,
1963         &o2hb_region_attr_pid.attr,
1964         NULL,
1965 };
1966 
1967 static ssize_t o2hb_region_show(struct config_item *item,
1968                                 struct configfs_attribute *attr,
1969                                 char *page)
1970 {
1971         struct o2hb_region *reg = to_o2hb_region(item);
1972         struct o2hb_region_attribute *o2hb_region_attr =
1973                 container_of(attr, struct o2hb_region_attribute, attr);
1974         ssize_t ret = 0;
1975 
1976         if (o2hb_region_attr->show)
1977                 ret = o2hb_region_attr->show(reg, page);
1978         return ret;
1979 }
1980 
1981 static ssize_t o2hb_region_store(struct config_item *item,
1982                                  struct configfs_attribute *attr,
1983                                  const char *page, size_t count)
1984 {
1985         struct o2hb_region *reg = to_o2hb_region(item);
1986         struct o2hb_region_attribute *o2hb_region_attr =
1987                 container_of(attr, struct o2hb_region_attribute, attr);
1988         ssize_t ret = -EINVAL;
1989 
1990         if (o2hb_region_attr->store)
1991                 ret = o2hb_region_attr->store(reg, page, count);
1992         return ret;
1993 }
1994 
1995 static struct configfs_item_operations o2hb_region_item_ops = {
1996         .release                = o2hb_region_release,
1997         .show_attribute         = o2hb_region_show,
1998         .store_attribute        = o2hb_region_store,
1999 };
2000 
2001 static struct config_item_type o2hb_region_type = {
2002         .ct_item_ops    = &o2hb_region_item_ops,
2003         .ct_attrs       = o2hb_region_attrs,
2004         .ct_owner       = THIS_MODULE,
2005 };
2006 
2007 /* heartbeat set */
2008 
2009 struct o2hb_heartbeat_group {
2010         struct config_group hs_group;
2011         /* some stuff? */
2012 };
2013 
2014 static struct o2hb_heartbeat_group *to_o2hb_heartbeat_group(struct config_group *group)
2015 {
2016         return group ?
2017                 container_of(group, struct o2hb_heartbeat_group, hs_group)
2018                 : NULL;
2019 }
2020 
2021 static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
2022 {
2023         int ret = -ENOMEM;
2024 
2025         reg->hr_debug_dir =
2026                 debugfs_create_dir(config_item_name(&reg->hr_item), dir);
2027         if (!reg->hr_debug_dir) {
2028                 mlog_errno(ret);
2029                 goto bail;
2030         }
2031 
2032         reg->hr_debug_livenodes =
2033                         o2hb_debug_create(O2HB_DEBUG_LIVENODES,
2034                                           reg->hr_debug_dir,
2035                                           &(reg->hr_db_livenodes),
2036                                           sizeof(*(reg->hr_db_livenodes)),
2037                                           O2HB_DB_TYPE_REGION_LIVENODES,
2038                                           sizeof(reg->hr_live_node_bitmap),
2039                                           O2NM_MAX_NODES, reg);
2040         if (!reg->hr_debug_livenodes) {
2041                 mlog_errno(ret);
2042                 goto bail;
2043         }
2044 
2045         reg->hr_debug_regnum =
2046                         o2hb_debug_create(O2HB_DEBUG_REGION_NUMBER,
2047                                           reg->hr_debug_dir,
2048                                           &(reg->hr_db_regnum),
2049                                           sizeof(*(reg->hr_db_regnum)),
2050                                           O2HB_DB_TYPE_REGION_NUMBER,
2051                                           0, O2NM_MAX_NODES, reg);
2052         if (!reg->hr_debug_regnum) {
2053                 mlog_errno(ret);
2054                 goto bail;
2055         }
2056 
2057         reg->hr_debug_elapsed_time =
2058                         o2hb_debug_create(O2HB_DEBUG_REGION_ELAPSED_TIME,
2059                                           reg->hr_debug_dir,
2060                                           &(reg->hr_db_elapsed_time),
2061                                           sizeof(*(reg->hr_db_elapsed_time)),
2062                                           O2HB_DB_TYPE_REGION_ELAPSED_TIME,
2063                                           0, 0, reg);
2064         if (!reg->hr_debug_elapsed_time) {
2065                 mlog_errno(ret);
2066                 goto bail;
2067         }
2068 
2069         reg->hr_debug_pinned =
2070                         o2hb_debug_create(O2HB_DEBUG_REGION_PINNED,
2071                                           reg->hr_debug_dir,
2072                                           &(reg->hr_db_pinned),
2073                                           sizeof(*(reg->hr_db_pinned)),
2074                                           O2HB_DB_TYPE_REGION_PINNED,
2075                                           0, 0, reg);
2076         if (!reg->hr_debug_pinned) {
2077                 mlog_errno(ret);
2078                 goto bail;
2079         }
2080 
2081         ret = 0;
2082 bail:
2083         return ret;
2084 }
2085 
2086 static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *group,
2087                                                           const char *name)
2088 {
2089         struct o2hb_region *reg = NULL;
2090         int ret;
2091 
2092         reg = kzalloc(sizeof(struct o2hb_region), GFP_KERNEL);
2093         if (reg == NULL)
2094                 return ERR_PTR(-ENOMEM);
2095 
2096         if (strlen(name) > O2HB_MAX_REGION_NAME_LEN) {
2097                 ret = -ENAMETOOLONG;
2098                 goto free;
2099         }
2100 
2101         spin_lock(&o2hb_live_lock);
2102         reg->hr_region_num = 0;
2103         if (o2hb_global_heartbeat_active()) {
2104                 reg->hr_region_num = find_first_zero_bit(o2hb_region_bitmap,
2105                                                          O2NM_MAX_REGIONS);
2106                 if (reg->hr_region_num >= O2NM_MAX_REGIONS) {
2107                         spin_unlock(&o2hb_live_lock);
2108                         ret = -EFBIG;
2109                         goto free;
2110                 }
2111                 set_bit(reg->hr_region_num, o2hb_region_bitmap);
2112         }
2113         list_add_tail(&reg->hr_all_item, &o2hb_all_regions);
2114         spin_unlock(&o2hb_live_lock);
2115 
2116         config_item_init_type_name(&reg->hr_item, name, &o2hb_region_type);
2117 
2118         ret = o2hb_debug_region_init(reg, o2hb_debug_dir);
2119         if (ret) {
2120                 config_item_put(&reg->hr_item);
2121                 goto free;
2122         }
2123 
2124         return &reg->hr_item;
2125 free:
2126         kfree(reg);
2127         return ERR_PTR(ret);
2128 }
2129 
2130 static void o2hb_heartbeat_group_drop_item(struct config_group *group,
2131                                            struct config_item *item)
2132 {
2133         struct task_struct *hb_task;
2134         struct o2hb_region *reg = to_o2hb_region(item);
2135         int quorum_region = 0;
2136 
2137         /* stop the thread when the user removes the region dir */
2138         spin_lock(&o2hb_live_lock);
2139         hb_task = reg->hr_task;
2140         reg->hr_task = NULL;
2141         reg->hr_item_dropped = 1;
2142         spin_unlock(&o2hb_live_lock);
2143 
2144         if (hb_task)
2145                 kthread_stop(hb_task);
2146 
2147         if (o2hb_global_heartbeat_active()) {
2148                 spin_lock(&o2hb_live_lock);
2149                 clear_bit(reg->hr_region_num, o2hb_region_bitmap);
2150                 clear_bit(reg->hr_region_num, o2hb_live_region_bitmap);
2151                 if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
2152                         quorum_region = 1;
2153                 clear_bit(reg->hr_region_num, o2hb_quorum_region_bitmap);
2154                 spin_unlock(&o2hb_live_lock);
2155                 printk(KERN_NOTICE "o2hb: Heartbeat %s on region %s (%s)\n",
2156                        ((atomic_read(&reg->hr_steady_iterations) == 0) ?
2157                         "stopped" : "start aborted"), config_item_name(item),
2158                        reg->hr_dev_name);
2159         }
2160 
2161         /*
2162          * If we're racing a dev_write(), we need to wake them.  They will
2163          * check reg->hr_task
2164          */
2165         if (atomic_read(&reg->hr_steady_iterations) != 0) {
2166                 reg->hr_aborted_start = 1;
2167                 atomic_set(&reg->hr_steady_iterations, 0);
2168                 wake_up(&o2hb_steady_queue);
2169         }
2170 
2171         config_item_put(item);
2172 
2173         if (!o2hb_global_heartbeat_active() || !quorum_region)
2174                 return;
2175 
2176         /*
2177          * If global heartbeat active and there are dependent users,
2178          * pin all regions if quorum region count <= CUT_OFF
2179          */
2180         spin_lock(&o2hb_live_lock);
2181 
2182         if (!o2hb_dependent_users)
2183                 goto unlock;
2184 
2185         if (o2hb_pop_count(&o2hb_quorum_region_bitmap,
2186                            O2NM_MAX_REGIONS) <= O2HB_PIN_CUT_OFF)
2187                 o2hb_region_pin(NULL);
2188 
2189 unlock:
2190         spin_unlock(&o2hb_live_lock);
2191 }
2192 
2193 struct o2hb_heartbeat_group_attribute {
2194         struct configfs_attribute attr;
2195         ssize_t (*show)(struct o2hb_heartbeat_group *, char *);
2196         ssize_t (*store)(struct o2hb_heartbeat_group *, const char *, size_t);
2197 };
2198 
2199 static ssize_t o2hb_heartbeat_group_show(struct config_item *item,
2200                                          struct configfs_attribute *attr,
2201                                          char *page)
2202 {
2203         struct o2hb_heartbeat_group *reg = to_o2hb_heartbeat_group(to_config_group(item));
2204         struct o2hb_heartbeat_group_attribute *o2hb_heartbeat_group_attr =
2205                 container_of(attr, struct o2hb_heartbeat_group_attribute, attr);
2206         ssize_t ret = 0;
2207 
2208         if (o2hb_heartbeat_group_attr->show)
2209                 ret = o2hb_heartbeat_group_attr->show(reg, page);
2210         return ret;
2211 }
2212 
2213 static ssize_t o2hb_heartbeat_group_store(struct config_item *item,
2214                                           struct configfs_attribute *attr,
2215                                           const char *page, size_t count)
2216 {
2217         struct o2hb_heartbeat_group *reg = to_o2hb_heartbeat_group(to_config_group(item));
2218         struct o2hb_heartbeat_group_attribute *o2hb_heartbeat_group_attr =
2219                 container_of(attr, struct o2hb_heartbeat_group_attribute, attr);
2220         ssize_t ret = -EINVAL;
2221 
2222         if (o2hb_heartbeat_group_attr->store)
2223                 ret = o2hb_heartbeat_group_attr->store(reg, page, count);
2224         return ret;
2225 }
2226 
2227 static ssize_t o2hb_heartbeat_group_threshold_show(struct o2hb_heartbeat_group *group,
2228                                                      char *page)
2229 {
2230         return sprintf(page, "%u\n", o2hb_dead_threshold);
2231 }
2232 
2233 static ssize_t o2hb_heartbeat_group_threshold_store(struct o2hb_heartbeat_group *group,
2234                                                     const char *page,
2235                                                     size_t count)
2236 {
2237         unsigned long tmp;
2238         char *p = (char *)page;
2239 
2240         tmp = simple_strtoul(p, &p, 10);
2241         if (!p || (*p && (*p != '\n')))
2242                 return -EINVAL;
2243 
2244         /* this will validate ranges for us. */
2245         o2hb_dead_threshold_set((unsigned int) tmp);
2246 
2247         return count;
2248 }
2249 
2250 static
2251 ssize_t o2hb_heartbeat_group_mode_show(struct o2hb_heartbeat_group *group,
2252                                        char *page)
2253 {
2254         return sprintf(page, "%s\n",
2255                        o2hb_heartbeat_mode_desc[o2hb_heartbeat_mode]);
2256 }
2257 
2258 static
2259 ssize_t o2hb_heartbeat_group_mode_store(struct o2hb_heartbeat_group *group,
2260                                         const char *page, size_t count)
2261 {
2262         unsigned int i;
2263         int ret;
2264         size_t len;
2265 
2266         len = (page[count - 1] == '\n') ? count - 1 : count;
2267         if (!len)
2268                 return -EINVAL;
2269 
2270         for (i = 0; i < O2HB_HEARTBEAT_NUM_MODES; ++i) {
2271                 if (strnicmp(page, o2hb_heartbeat_mode_desc[i], len))
2272                         continue;
2273 
2274                 ret = o2hb_global_hearbeat_mode_set(i);
2275                 if (!ret)
2276                         printk(KERN_NOTICE "o2hb: Heartbeat mode set to %s\n",
2277                                o2hb_heartbeat_mode_desc[i]);
2278                 return count;
2279         }
2280 
2281         return -EINVAL;
2282 
2283 }
2284 
2285 static struct o2hb_heartbeat_group_attribute o2hb_heartbeat_group_attr_threshold = {
2286         .attr   = { .ca_owner = THIS_MODULE,
2287                     .ca_name = "dead_threshold",
2288                     .ca_mode = S_IRUGO | S_IWUSR },
2289         .show   = o2hb_heartbeat_group_threshold_show,
2290         .store  = o2hb_heartbeat_group_threshold_store,
2291 };
2292 
2293 static struct o2hb_heartbeat_group_attribute o2hb_heartbeat_group_attr_mode = {
2294         .attr   = { .ca_owner = THIS_MODULE,
2295                 .ca_name = "mode",
2296                 .ca_mode = S_IRUGO | S_IWUSR },
2297         .show   = o2hb_heartbeat_group_mode_show,
2298         .store  = o2hb_heartbeat_group_mode_store,
2299 };
2300 
2301 static struct configfs_attribute *o2hb_heartbeat_group_attrs[] = {
2302         &o2hb_heartbeat_group_attr_threshold.attr,
2303         &o2hb_heartbeat_group_attr_mode.attr,
2304         NULL,
2305 };
2306 
2307 static struct configfs_item_operations o2hb_hearbeat_group_item_ops = {
2308         .show_attribute         = o2hb_heartbeat_group_show,
2309         .store_attribute        = o2hb_heartbeat_group_store,
2310 };
2311 
2312 static struct configfs_group_operations o2hb_heartbeat_group_group_ops = {
2313         .make_item      = o2hb_heartbeat_group_make_item,
2314         .drop_item      = o2hb_heartbeat_group_drop_item,
2315 };
2316 
2317 static struct config_item_type o2hb_heartbeat_group_type = {
2318         .ct_group_ops   = &o2hb_heartbeat_group_group_ops,
2319         .ct_item_ops    = &o2hb_hearbeat_group_item_ops,
2320         .ct_attrs       = o2hb_heartbeat_group_attrs,
2321         .ct_owner       = THIS_MODULE,
2322 };
2323 
2324 /* this is just here to avoid touching group in heartbeat.h which the
2325  * entire damn world #includes */
2326 struct config_group *o2hb_alloc_hb_set(void)
2327 {
2328         struct o2hb_heartbeat_group *hs = NULL;
2329         struct config_group *ret = NULL;
2330 
2331         hs = kzalloc(sizeof(struct o2hb_heartbeat_group), GFP_KERNEL);
2332         if (hs == NULL)
2333                 goto out;
2334 
2335         config_group_init_type_name(&hs->hs_group, "heartbeat",
2336                                     &o2hb_heartbeat_group_type);
2337 
2338         ret = &hs->hs_group;
2339 out:
2340         if (ret == NULL)
2341                 kfree(hs);
2342         return ret;
2343 }
2344 
2345 void o2hb_free_hb_set(struct config_group *group)
2346 {
2347         struct o2hb_heartbeat_group *hs = to_o2hb_heartbeat_group(group);
2348         kfree(hs);
2349 }
2350 
2351 /* hb callback registration and issuing */
2352 
2353 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type)
2354 {
2355         if (type == O2HB_NUM_CB)
2356                 return ERR_PTR(-EINVAL);
2357 
2358         return &o2hb_callbacks[type];
2359 }
2360 
2361 void o2hb_setup_callback(struct o2hb_callback_func *hc,
2362                          enum o2hb_callback_type type,
2363                          o2hb_cb_func *func,
2364                          void *data,
2365                          int priority)
2366 {
2367         INIT_LIST_HEAD(&hc->hc_item);
2368         hc->hc_func = func;
2369         hc->hc_data = data;
2370         hc->hc_priority = priority;
2371         hc->hc_type = type;
2372         hc->hc_magic = O2HB_CB_MAGIC;
2373 }
2374 EXPORT_SYMBOL_GPL(o2hb_setup_callback);
2375 
2376 /*
2377  * In local heartbeat mode, region_uuid passed matches the dlm domain name.
2378  * In global heartbeat mode, region_uuid passed is NULL.
2379  *
2380  * In local, we only pin the matching region. In global we pin all the active
2381  * regions.
2382  */
2383 static int o2hb_region_pin(const char *region_uuid)
2384 {
2385         int ret = 0, found = 0;
2386         struct o2hb_region *reg;
2387         char *uuid;
2388 
2389         assert_spin_locked(&o2hb_live_lock);
2390 
2391         list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
2392                 uuid = config_item_name(&reg->hr_item);
2393 
2394                 /* local heartbeat */
2395                 if (region_uuid) {
2396                         if (strcmp(region_uuid, uuid))
2397                                 continue;
2398                         found = 1;
2399                 }
2400 
2401                 if (reg->hr_item_pinned || reg->hr_item_dropped)
2402                         goto skip_pin;
2403 
2404                 /* Ignore ENOENT only for local hb (userdlm domain) */
2405                 ret = o2nm_depend_item(&reg->hr_item);
2406                 if (!ret) {
2407                         mlog(ML_CLUSTER, "Pin region %s\n", uuid);
2408                         reg->hr_item_pinned = 1;
2409                 } else {
2410                         if (ret == -ENOENT && found)
2411                                 ret = 0;
2412                         else {
2413                                 mlog(ML_ERROR, "Pin region %s fails with %d\n",
2414                                      uuid, ret);
2415                                 break;
2416                         }
2417                 }
2418 skip_pin:
2419                 if (found)
2420                         break;
2421         }
2422 
2423         return ret;
2424 }
2425 
2426 /*
2427  * In local heartbeat mode, region_uuid passed matches the dlm domain name.
2428  * In global heartbeat mode, region_uuid passed is NULL.
2429  *
2430  * In local, we only unpin the matching region. In global we unpin all the
2431  * active regions.
2432  */
2433 static void o2hb_region_unpin(const char *region_uuid)
2434 {
2435         struct o2hb_region *reg;
2436         char *uuid;
2437         int found = 0;
2438 
2439         assert_spin_locked(&o2hb_live_lock);
2440 
2441         list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
2442                 uuid = config_item_name(&reg->hr_item);
2443                 if (region_uuid) {
2444                         if (strcmp(region_uuid, uuid))
2445                                 continue;
2446                         found = 1;
2447                 }
2448 
2449                 if (reg->hr_item_pinned) {
2450                         mlog(ML_CLUSTER, "Unpin region %s\n", uuid);
2451                         o2nm_undepend_item(&reg->hr_item);
2452                         reg->hr_item_pinned = 0;
2453                 }
2454                 if (found)
2455                         break;
2456         }
2457 }
2458 
2459 static int o2hb_region_inc_user(const char *region_uuid)
2460 {
2461         int ret = 0;
2462 
2463         spin_lock(&o2hb_live_lock);
2464 
2465         /* local heartbeat */
2466         if (!o2hb_global_heartbeat_active()) {
2467             ret = o2hb_region_pin(region_uuid);
2468             goto unlock;
2469         }
2470 
2471         /*
2472          * if global heartbeat active and this is the first dependent user,
2473          * pin all regions if quorum region count <= CUT_OFF
2474          */
2475         o2hb_dependent_users++;
2476         if (o2hb_dependent_users > 1)
2477                 goto unlock;
2478 
2479         if (o2hb_pop_count(&o2hb_quorum_region_bitmap,
2480                            O2NM_MAX_REGIONS) <= O2HB_PIN_CUT_OFF)
2481                 ret = o2hb_region_pin(NULL);
2482 
2483 unlock:
2484         spin_unlock(&o2hb_live_lock);
2485         return ret;
2486 }
2487 
2488 void o2hb_region_dec_user(const char *region_uuid)
2489 {
2490         spin_lock(&o2hb_live_lock);
2491 
2492         /* local heartbeat */
2493         if (!o2hb_global_heartbeat_active()) {
2494             o2hb_region_unpin(region_uuid);
2495             goto unlock;
2496         }
2497 
2498         /*
2499          * if global heartbeat active and there are no dependent users,
2500          * unpin all quorum regions
2501          */
2502         o2hb_dependent_users--;
2503         if (!o2hb_dependent_users)
2504                 o2hb_region_unpin(NULL);
2505 
2506 unlock:
2507         spin_unlock(&o2hb_live_lock);
2508 }
2509 
2510 int o2hb_register_callback(const char *region_uuid,
2511                            struct o2hb_callback_func *hc)
2512 {
2513         struct o2hb_callback_func *tmp;
2514         struct list_head *iter;
2515         struct o2hb_callback *hbcall;
2516         int ret;
2517 
2518         BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
2519         BUG_ON(!list_empty(&hc->hc_item));
2520 
2521         hbcall = hbcall_from_type(hc->hc_type);
2522         if (IS_ERR(hbcall)) {
2523                 ret = PTR_ERR(hbcall);
2524                 goto out;
2525         }
2526 
2527         if (region_uuid) {
2528                 ret = o2hb_region_inc_user(region_uuid);
2529                 if (ret) {
2530                         mlog_errno(ret);
2531                         goto out;
2532                 }
2533         }
2534 
2535         down_write(&o2hb_callback_sem);
2536 
2537         list_for_each(iter, &hbcall->list) {
2538                 tmp = list_entry(iter, struct o2hb_callback_func, hc_item);
2539                 if (hc->hc_priority < tmp->hc_priority) {
2540                         list_add_tail(&hc->hc_item, iter);
2541                         break;
2542                 }
2543         }
2544         if (list_empty(&hc->hc_item))
2545                 list_add_tail(&hc->hc_item, &hbcall->list);
2546 
2547         up_write(&o2hb_callback_sem);
2548         ret = 0;
2549 out:
2550         mlog(ML_CLUSTER, "returning %d on behalf of %p for funcs %p\n",
2551              ret, __builtin_return_address(0), hc);
2552         return ret;
2553 }
2554 EXPORT_SYMBOL_GPL(o2hb_register_callback);
2555 
2556 void o2hb_unregister_callback(const char *region_uuid,
2557                               struct o2hb_callback_func *hc)
2558 {
2559         BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
2560 
2561         mlog(ML_CLUSTER, "on behalf of %p for funcs %p\n",
2562              __builtin_return_address(0), hc);
2563 
2564         /* XXX Can this happen _with_ a region reference? */
2565         if (list_empty(&hc->hc_item))
2566                 return;
2567 
2568         if (region_uuid)
2569                 o2hb_region_dec_user(region_uuid);
2570 
2571         down_write(&o2hb_callback_sem);
2572 
2573         list_del_init(&hc->hc_item);
2574 
2575         up_write(&o2hb_callback_sem);
2576 }
2577 EXPORT_SYMBOL_GPL(o2hb_unregister_callback);
2578 
2579 int o2hb_check_node_heartbeating(u8 node_num)
2580 {
2581         unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
2582 
2583         o2hb_fill_node_map(testing_map, sizeof(testing_map));
2584         if (!test_bit(node_num, testing_map)) {
2585                 mlog(ML_HEARTBEAT,
2586                      "node (%u) does not have heartbeating enabled.\n",
2587                      node_num);
2588                 return 0;
2589         }
2590 
2591         return 1;
2592 }
2593 EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating);
2594 
2595 int o2hb_check_node_heartbeating_from_callback(u8 node_num)
2596 {
2597         unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
2598 
2599         o2hb_fill_node_map_from_callback(testing_map, sizeof(testing_map));
2600         if (!test_bit(node_num, testing_map)) {
2601                 mlog(ML_HEARTBEAT,
2602                      "node (%u) does not have heartbeating enabled.\n",
2603                      node_num);
2604                 return 0;
2605         }
2606 
2607         return 1;
2608 }
2609 EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating_from_callback);
2610 
2611 /* Makes sure our local node is configured with a node number, and is
2612  * heartbeating. */
2613 int o2hb_check_local_node_heartbeating(void)
2614 {
2615         u8 node_num;
2616 
2617         /* if this node was set then we have networking */
2618         node_num = o2nm_this_node();
2619         if (node_num == O2NM_MAX_NODES) {
2620                 mlog(ML_HEARTBEAT, "this node has not been configured.\n");
2621                 return 0;
2622         }
2623 
2624         return o2hb_check_node_heartbeating(node_num);
2625 }
2626 EXPORT_SYMBOL_GPL(o2hb_check_local_node_heartbeating);
2627 
2628 /*
2629  * this is just a hack until we get the plumbing which flips file systems
2630  * read only and drops the hb ref instead of killing the node dead.
2631  */
2632 void o2hb_stop_all_regions(void)
2633 {
2634         struct o2hb_region *reg;
2635 
2636         mlog(ML_ERROR, "stopping heartbeat on all active regions.\n");
2637 
2638         spin_lock(&o2hb_live_lock);
2639 
2640         list_for_each_entry(reg, &o2hb_all_regions, hr_all_item)
2641                 reg->hr_unclean_stop = 1;
2642 
2643         spin_unlock(&o2hb_live_lock);
2644 }
2645 EXPORT_SYMBOL_GPL(o2hb_stop_all_regions);
2646 
2647 int o2hb_get_all_regions(char *region_uuids, u8 max_regions)
2648 {
2649         struct o2hb_region *reg;
2650         int numregs = 0;
2651         char *p;
2652 
2653         spin_lock(&o2hb_live_lock);
2654 
2655         p = region_uuids;
2656         list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
2657                 mlog(0, "Region: %s\n", config_item_name(&reg->hr_item));
2658                 if (numregs < max_regions) {
2659                         memcpy(p, config_item_name(&reg->hr_item),
2660                                O2HB_MAX_REGION_NAME_LEN);
2661                         p += O2HB_MAX_REGION_NAME_LEN;
2662                 }
2663                 numregs++;
2664         }
2665 
2666         spin_unlock(&o2hb_live_lock);
2667 
2668         return numregs;
2669 }
2670 EXPORT_SYMBOL_GPL(o2hb_get_all_regions);
2671 
2672 int o2hb_global_heartbeat_active(void)
2673 {
2674         return (o2hb_heartbeat_mode == O2HB_HEARTBEAT_GLOBAL);
2675 }
2676 EXPORT_SYMBOL(o2hb_global_heartbeat_active);
2677 

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