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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2004, 2005 Oracle.  All rights reserved.
  */
 
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/jiffies.h>
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/delay.h>
 #include <linux/file.h>
 #include <linux/kthread.h>
 #include <linux/configfs.h>
 #include <linux/random.h>
 #include <linux/crc32.h>
 #include <linux/time.h>
 #include <linux/debugfs.h>
 #include <linux/slab.h>
 #include <linux/bitmap.h>
 #include <linux/ktime.h>
 #include "heartbeat.h"
 #include "tcp.h"
 #include "nodemanager.h"
 #include "quorum.h"
 
 #include "masklog.h"
 
 
 /*
  * The first heartbeat pass had one global thread that would serialize all hb
  * callback calls.  This global serializing sem should only be removed once
  * we've made sure that all callees can deal with being called concurrently
  * from multiple hb region threads.
  */
 static DECLARE_RWSEM(o2hb_callback_sem);
 
 /*
  * multiple hb threads are watching multiple regions.  A node is live
  * whenever any of the threads sees activity from the node in its region.
  */
 static DEFINE_SPINLOCK(o2hb_live_lock);
 static struct list_head o2hb_live_slots[O2NM_MAX_NODES];
 static unsigned long o2hb_live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
 static LIST_HEAD(o2hb_node_events);
 static DECLARE_WAIT_QUEUE_HEAD(o2hb_steady_queue);
 
 /*
  * In global heartbeat, we maintain a series of region bitmaps.
  *  - o2hb_region_bitmap allows us to limit the region number to max region.
  *  - o2hb_live_region_bitmap tracks live regions (seen steady iterations).
  *  - o2hb_quorum_region_bitmap tracks live regions that have seen all nodes
  *      heartbeat on it.
  *  - o2hb_failed_region_bitmap tracks the regions that have seen io timeouts.
  */
 static unsigned long o2hb_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 static unsigned long o2hb_live_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 static unsigned long o2hb_quorum_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 static unsigned long o2hb_failed_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 
 #define O2HB_DB_TYPE_LIVENODES      0
 #define O2HB_DB_TYPE_LIVEREGIONS    1
 #define O2HB_DB_TYPE_QUORUMREGIONS  2
 #define O2HB_DB_TYPE_FAILEDREGIONS  3
 #define O2HB_DB_TYPE_REGION_LIVENODES   4
 #define O2HB_DB_TYPE_REGION_NUMBER  5
 #define O2HB_DB_TYPE_REGION_ELAPSED_TIME    6
 #define O2HB_DB_TYPE_REGION_PINNED  7
 struct o2hb_debug_buf {
     int db_type;
     int db_size;
     int db_len;
     void *db_data;
 };
 
 static struct o2hb_debug_buf *o2hb_db_livenodes;
 static struct o2hb_debug_buf *o2hb_db_liveregions;
 static struct o2hb_debug_buf *o2hb_db_quorumregions;
 static struct o2hb_debug_buf *o2hb_db_failedregions;
 
 #define O2HB_DEBUG_DIR          "o2hb"
 #define O2HB_DEBUG_LIVENODES        "livenodes"
 #define O2HB_DEBUG_LIVEREGIONS      "live_regions"
 #define O2HB_DEBUG_QUORUMREGIONS    "quorum_regions"
 #define O2HB_DEBUG_FAILEDREGIONS    "failed_regions"
 #define O2HB_DEBUG_REGION_NUMBER    "num"
 #define O2HB_DEBUG_REGION_ELAPSED_TIME  "elapsed_time_in_ms"
 #define O2HB_DEBUG_REGION_PINNED    "pinned"
 
 static struct dentry *o2hb_debug_dir;
 
 static LIST_HEAD(o2hb_all_regions);
 
 static struct o2hb_callback {
     struct list_head list;
 } o2hb_callbacks[O2HB_NUM_CB];
 
 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type);
 
 enum o2hb_heartbeat_modes {
     O2HB_HEARTBEAT_LOCAL        = 0,
     O2HB_HEARTBEAT_GLOBAL,
     O2HB_HEARTBEAT_NUM_MODES,
 };
 
 static const char *o2hb_heartbeat_mode_desc[O2HB_HEARTBEAT_NUM_MODES] = {
     "local",    /* O2HB_HEARTBEAT_LOCAL */
     "global",   /* O2HB_HEARTBEAT_GLOBAL */
 };
 
 unsigned int o2hb_dead_threshold = O2HB_DEFAULT_DEAD_THRESHOLD;
 static unsigned int o2hb_heartbeat_mode = O2HB_HEARTBEAT_LOCAL;
 
 /*
  * o2hb_dependent_users tracks the number of registered callbacks that depend
  * on heartbeat. o2net and o2dlm are two entities that register this callback.
  * However only o2dlm depends on the heartbeat. It does not want the heartbeat
  * to stop while a dlm domain is still active.
  */
 static unsigned int o2hb_dependent_users;
 
 /*
  * In global heartbeat mode, all regions are pinned if there are one or more
  * dependent users and the quorum region count is <= O2HB_PIN_CUT_OFF. All
  * regions are unpinned if the region count exceeds the cut off or the number
  * of dependent users falls to zero.
  */
 #define O2HB_PIN_CUT_OFF        3
 
 /*
  * In local heartbeat mode, we assume the dlm domain name to be the same as
  * region uuid. This is true for domains created for the file system but not
  * necessarily true for userdlm domains. This is a known limitation.
  *
  * In global heartbeat mode, we pin/unpin all o2hb regions. This solution
  * works for both file system and userdlm domains.
  */
 static int o2hb_region_pin(const char *region_uuid);
 static void o2hb_region_unpin(const char *region_uuid);
 
 /* Only sets a new threshold if there are no active regions.
  *
  * No locking or otherwise interesting code is required for reading
  * o2hb_dead_threshold as it can't change once regions are active and
  * it's not interesting to anyone until then anyway. */
 static void o2hb_dead_threshold_set(unsigned int threshold)
 {
     if (threshold > O2HB_MIN_DEAD_THRESHOLD) {
         spin_lock(&o2hb_live_lock);
         if (list_empty(&o2hb_all_regions))
             o2hb_dead_threshold = threshold;
         spin_unlock(&o2hb_live_lock);
     }
 }
 
 static int o2hb_global_heartbeat_mode_set(unsigned int hb_mode)
 {
     int ret = -1;
 
     if (hb_mode < O2HB_HEARTBEAT_NUM_MODES) {
         spin_lock(&o2hb_live_lock);
         if (list_empty(&o2hb_all_regions)) {
             o2hb_heartbeat_mode = hb_mode;
             ret = 0;
         }
         spin_unlock(&o2hb_live_lock);
     }
 
     return ret;
 }
 
 struct o2hb_node_event {
     struct list_head        hn_item;
     enum o2hb_callback_type hn_event_type;
     struct o2nm_node        *hn_node;
     int                     hn_node_num;
 };
 
 struct o2hb_disk_slot {
     struct o2hb_disk_heartbeat_block *ds_raw_block;
     u8          ds_node_num;
     u64         ds_last_time;
     u64         ds_last_generation;
     u16         ds_equal_samples;
     u16         ds_changed_samples;
     struct list_head    ds_live_item;
 };
 
 /* each thread owns a region.. when we're asked to tear down the region
  * we ask the thread to stop, who cleans up the region */
 struct o2hb_region {
     struct config_item  hr_item;
 
     struct list_head    hr_all_item;
     unsigned        hr_unclean_stop:1,
                 hr_aborted_start:1,
                 hr_item_pinned:1,
                 hr_item_dropped:1,
                 hr_node_deleted:1;
 
     /* protected by the hr_callback_sem */
     struct task_struct  *hr_task;
 
     unsigned int        hr_blocks;
     unsigned long long  hr_start_block;
 
     unsigned int        hr_block_bits;
     unsigned int        hr_block_bytes;
 
     unsigned int        hr_slots_per_page;
     unsigned int        hr_num_pages;
 
     struct page             **hr_slot_data;
     struct block_device *hr_bdev;
     struct o2hb_disk_slot   *hr_slots;
 
     /* live node map of this region */
     unsigned long       hr_live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
     unsigned int        hr_region_num;
 
     struct dentry       *hr_debug_dir;
     struct o2hb_debug_buf   *hr_db_livenodes;
     struct o2hb_debug_buf   *hr_db_regnum;
     struct o2hb_debug_buf   *hr_db_elapsed_time;
     struct o2hb_debug_buf   *hr_db_pinned;
 
     /* let the person setting up hb wait for it to return until it
      * has reached a 'steady' state.  This will be fixed when we have
      * a more complete api that doesn't lead to this sort of fragility. */
     atomic_t        hr_steady_iterations;
 
     /* terminate o2hb thread if it does not reach steady state
      * (hr_steady_iterations == 0) within hr_unsteady_iterations */
     atomic_t        hr_unsteady_iterations;
 
     unsigned int        hr_timeout_ms;
 
     /* randomized as the region goes up and down so that a node
      * recognizes a node going up and down in one iteration */
     u64         hr_generation;
 
     struct delayed_work hr_write_timeout_work;
     unsigned long       hr_last_timeout_start;
 
     /* negotiate timer, used to negotiate extending hb timeout. */
     struct delayed_work hr_nego_timeout_work;
     unsigned long       hr_nego_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
 
     /* Used during o2hb_check_slot to hold a copy of the block
      * being checked because we temporarily have to zero out the
      * crc field. */
     struct o2hb_disk_heartbeat_block *hr_tmp_block;
 
     /* Message key for negotiate timeout message. */
     unsigned int        hr_key;
     struct list_head    hr_handler_list;
 
     /* last hb status, 0 for success, other value for error. */
     int         hr_last_hb_status;
 };
 
 struct o2hb_bio_wait_ctxt {
     atomic_t          wc_num_reqs;
     struct completion wc_io_complete;
     int               wc_error;
 };
 
 #define O2HB_NEGO_TIMEOUT_MS (O2HB_MAX_WRITE_TIMEOUT_MS/2)
 
 enum {
     O2HB_NEGO_TIMEOUT_MSG = 1,
     O2HB_NEGO_APPROVE_MSG = 2,
 };
 
 struct o2hb_nego_msg {
     u8 node_num;
 };
 
 static void o2hb_write_timeout(struct work_struct *work)
 {
     int failed, quorum;
     struct o2hb_region *reg =
         container_of(work, struct o2hb_region,
                  hr_write_timeout_work.work);
 
     mlog(ML_ERROR, "Heartbeat write timeout to device %pg after %u "
          "milliseconds\n", reg->hr_bdev,
          jiffies_to_msecs(jiffies - reg->hr_last_timeout_start));
 
     if (o2hb_global_heartbeat_active()) {
         spin_lock(&o2hb_live_lock);
         if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
             set_bit(reg->hr_region_num, o2hb_failed_region_bitmap);
         failed = bitmap_weight(o2hb_failed_region_bitmap,
                     O2NM_MAX_REGIONS);
         quorum = bitmap_weight(o2hb_quorum_region_bitmap,
                     O2NM_MAX_REGIONS);
         spin_unlock(&o2hb_live_lock);
 
         mlog(ML_HEARTBEAT, "Number of regions %d, failed regions %d\n",
              quorum, failed);
 
         /*
          * Fence if the number of failed regions >= half the number
          * of  quorum regions
          */
         if ((failed << 1) < quorum)
             return;
     }
 
     o2quo_disk_timeout();
 }
 
 static void o2hb_arm_timeout(struct o2hb_region *reg)
 {
     /* Arm writeout only after thread reaches steady state */
     if (atomic_read(&reg->hr_steady_iterations) != 0)
         return;
 
     mlog(ML_HEARTBEAT, "Queue write timeout for %u ms\n",
          O2HB_MAX_WRITE_TIMEOUT_MS);
 
     if (o2hb_global_heartbeat_active()) {
         spin_lock(&o2hb_live_lock);
         clear_bit(reg->hr_region_num, o2hb_failed_region_bitmap);
         spin_unlock(&o2hb_live_lock);
     }
     cancel_delayed_work(&reg->hr_write_timeout_work);
     schedule_delayed_work(&reg->hr_write_timeout_work,
                   msecs_to_jiffies(O2HB_MAX_WRITE_TIMEOUT_MS));
 
     cancel_delayed_work(&reg->hr_nego_timeout_work);
     /* negotiate timeout must be less than write timeout. */
     schedule_delayed_work(&reg->hr_nego_timeout_work,
                   msecs_to_jiffies(O2HB_NEGO_TIMEOUT_MS));
     memset(reg->hr_nego_node_bitmap, 0, sizeof(reg->hr_nego_node_bitmap));
 }
 
 static void o2hb_disarm_timeout(struct o2hb_region *reg)
 {
     cancel_delayed_work_sync(&reg->hr_write_timeout_work);
     cancel_delayed_work_sync(&reg->hr_nego_timeout_work);
 }
 
 static int o2hb_send_nego_msg(int key, int type, u8 target)
 {
     struct o2hb_nego_msg msg;
     int status, ret;
 
     msg.node_num = o2nm_this_node();
 again:
     ret = o2net_send_message(type, key, &msg, sizeof(msg),
             target, &status);
 
     if (ret == -EAGAIN || ret == -ENOMEM) {
         msleep(100);
         goto again;
     }
 
     return ret;
 }
 
 static void o2hb_nego_timeout(struct work_struct *work)
 {
     unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
     int master_node, i, ret;
     struct o2hb_region *reg;
 
     reg = container_of(work, struct o2hb_region, hr_nego_timeout_work.work);
     /* don't negotiate timeout if last hb failed since it is very
      * possible io failed. Should let write timeout fence self.
      */
     if (reg->hr_last_hb_status)
         return;
 
     o2hb_fill_node_map(live_node_bitmap, sizeof(live_node_bitmap));
     /* lowest node as master node to make negotiate decision. */
     master_node = find_first_bit(live_node_bitmap, O2NM_MAX_NODES);
 
     if (master_node == o2nm_this_node()) {
         if (!test_bit(master_node, reg->hr_nego_node_bitmap)) {
             printk(KERN_NOTICE "o2hb: node %d hb write hung for %ds on region %s (%pg).\n",
                 o2nm_this_node(), O2HB_NEGO_TIMEOUT_MS/1000,
                 config_item_name(&reg->hr_item), reg->hr_bdev);
             set_bit(master_node, reg->hr_nego_node_bitmap);
         }
         if (memcmp(reg->hr_nego_node_bitmap, live_node_bitmap,
                 sizeof(reg->hr_nego_node_bitmap))) {
             /* check negotiate bitmap every second to do timeout
              * approve decision.
              */
             schedule_delayed_work(&reg->hr_nego_timeout_work,
                 msecs_to_jiffies(1000));
 
             return;
         }
 
         printk(KERN_NOTICE "o2hb: all nodes hb write hung, maybe region %s (%pg) is down.\n",
             config_item_name(&reg->hr_item), reg->hr_bdev);
         /* approve negotiate timeout request. */
         o2hb_arm_timeout(reg);
 
         i = -1;
         while ((i = find_next_bit(live_node_bitmap,
                 O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
             if (i == master_node)
                 continue;
 
             mlog(ML_HEARTBEAT, "send NEGO_APPROVE msg to node %d\n", i);
             ret = o2hb_send_nego_msg(reg->hr_key,
                     O2HB_NEGO_APPROVE_MSG, i);
             if (ret)
                 mlog(ML_ERROR, "send NEGO_APPROVE msg to node %d fail %d\n",
                     i, ret);
         }
     } else {
         /* negotiate timeout with master node. */
         printk(KERN_NOTICE "o2hb: node %d hb write hung for %ds on region %s (%pg), negotiate timeout with node %d.\n",
             o2nm_this_node(), O2HB_NEGO_TIMEOUT_MS/1000, config_item_name(&reg->hr_item),
             reg->hr_bdev, master_node);
         ret = o2hb_send_nego_msg(reg->hr_key, O2HB_NEGO_TIMEOUT_MSG,
                 master_node);
         if (ret)
             mlog(ML_ERROR, "send NEGO_TIMEOUT msg to node %d fail %d\n",
                 master_node, ret);
     }
 }
 
 static int o2hb_nego_timeout_handler(struct o2net_msg *msg, u32 len, void *data,
                 void **ret_data)
 {
     struct o2hb_region *reg = data;
     struct o2hb_nego_msg *nego_msg;
 
     nego_msg = (struct o2hb_nego_msg *)msg->buf;
     printk(KERN_NOTICE "o2hb: receive negotiate timeout message from node %d on region %s (%pg).\n",
         nego_msg->node_num, config_item_name(&reg->hr_item), reg->hr_bdev);
     if (nego_msg->node_num < O2NM_MAX_NODES)
         set_bit(nego_msg->node_num, reg->hr_nego_node_bitmap);
     else
         mlog(ML_ERROR, "got nego timeout message from bad node.\n");
 
     return 0;
 }
 
 static int o2hb_nego_approve_handler(struct o2net_msg *msg, u32 len, void *data,
                 void **ret_data)
 {
     struct o2hb_region *reg = data;
 
     printk(KERN_NOTICE "o2hb: negotiate timeout approved by master node on region %s (%pg).\n",
         config_item_name(&reg->hr_item), reg->hr_bdev);
     o2hb_arm_timeout(reg);
     return 0;
 }
 
 static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc)
 {
     atomic_set(&wc->wc_num_reqs, 1);
     init_completion(&wc->wc_io_complete);
     wc->wc_error = 0;
 }
 
 /* Used in error paths too */
 static inline void o2hb_bio_wait_dec(struct o2hb_bio_wait_ctxt *wc,
                      unsigned int num)
 {
     /* sadly atomic_sub_and_test() isn't available on all platforms.  The
      * good news is that the fast path only completes one at a time */
     while(num--) {
         if (atomic_dec_and_test(&wc->wc_num_reqs)) {
             BUG_ON(num > 0);
             complete(&wc->wc_io_complete);
         }
     }
 }
 
 static void o2hb_wait_on_io(struct o2hb_bio_wait_ctxt *wc)
 {
     o2hb_bio_wait_dec(wc, 1);
     wait_for_completion(&wc->wc_io_complete);
 }
 
 static void o2hb_bio_end_io(struct bio *bio)
 {
     struct o2hb_bio_wait_ctxt *wc = bio->bi_private;
 
     if (bio->bi_status) {
         mlog(ML_ERROR, "IO Error %d\n", bio->bi_status);
         wc->wc_error = blk_status_to_errno(bio->bi_status);
     }
 
     o2hb_bio_wait_dec(wc, 1);
     bio_put(bio);
 }
 
 /* Setup a Bio to cover I/O against num_slots slots starting at
  * start_slot. */
 static struct bio *o2hb_setup_one_bio(struct o2hb_region *reg,
                       struct o2hb_bio_wait_ctxt *wc,
                       unsigned int *current_slot,
                       unsigned int max_slots, blk_opf_t opf)
 {
     int len, current_page;
     unsigned int vec_len, vec_start;
     unsigned int bits = reg->hr_block_bits;
     unsigned int spp = reg->hr_slots_per_page;
     unsigned int cs = *current_slot;
     struct bio *bio;
     struct page *page;
 
     /* Testing has shown this allocation to take long enough under
      * GFP_KERNEL that the local node can get fenced. It would be
      * nicest if we could pre-allocate these bios and avoid this
      * all together. */
     bio = bio_alloc(reg->hr_bdev, 16, opf, GFP_ATOMIC);
     if (!bio) {
         mlog(ML_ERROR, "Could not alloc slots BIO!\n");
         bio = ERR_PTR(-ENOMEM);
         goto bail;
     }
 
     /* Must put everything in 512 byte sectors for the bio... */
     bio->bi_iter.bi_sector = (reg->hr_start_block + cs) << (bits - 9);
     bio->bi_private = wc;
     bio->bi_end_io = o2hb_bio_end_io;
 
     vec_start = (cs << bits) % PAGE_SIZE;
     while(cs < max_slots) {
         current_page = cs / spp;
         page = reg->hr_slot_data[current_page];
 
         vec_len = min(PAGE_SIZE - vec_start,
                   (max_slots-cs) * (PAGE_SIZE/spp) );
 
         mlog(ML_HB_BIO, "page %d, vec_len = %u, vec_start = %u\n",
              current_page, vec_len, vec_start);
 
         len = bio_add_page(bio, page, vec_len, vec_start);
         if (len != vec_len) break;
 
         cs += vec_len / (PAGE_SIZE/spp);
         vec_start = 0;
     }
 
 bail:
     *current_slot = cs;
     return bio;
 }
 
 static int o2hb_read_slots(struct o2hb_region *reg,
                unsigned int begin_slot,
                unsigned int max_slots)
 {
     unsigned int current_slot = begin_slot;
     int status;
     struct o2hb_bio_wait_ctxt wc;
     struct bio *bio;
 
     o2hb_bio_wait_init(&wc);
 
     while(current_slot < max_slots) {
         bio = o2hb_setup_one_bio(reg, &wc, &current_slot, max_slots,
                      REQ_OP_READ);
         if (IS_ERR(bio)) {
             status = PTR_ERR(bio);
             mlog_errno(status);
             goto bail_and_wait;
         }
 
         atomic_inc(&wc.wc_num_reqs);
         submit_bio(bio);
     }
 
     status = 0;
 
 bail_and_wait:
     o2hb_wait_on_io(&wc);
     if (wc.wc_error && !status)
         status = wc.wc_error;
 
     return status;
 }
 
 static int o2hb_issue_node_write(struct o2hb_region *reg,
                  struct o2hb_bio_wait_ctxt *write_wc)
 {
     int status;
     unsigned int slot;
     struct bio *bio;
 
     o2hb_bio_wait_init(write_wc);
 
     slot = o2nm_this_node();
 
     bio = o2hb_setup_one_bio(reg, write_wc, &slot, slot+1,
                  REQ_OP_WRITE | REQ_SYNC);
     if (IS_ERR(bio)) {
         status = PTR_ERR(bio);
         mlog_errno(status);
         goto bail;
     }
 
     atomic_inc(&write_wc->wc_num_reqs);
     submit_bio(bio);
 
     status = 0;
 bail:
     return status;
 }
 
 static u32 o2hb_compute_block_crc_le(struct o2hb_region *reg,
                      struct o2hb_disk_heartbeat_block *hb_block)
 {
     __le32 old_cksum;
     u32 ret;
 
     /* We want to compute the block crc with a 0 value in the
      * hb_cksum field. Save it off here and replace after the
      * crc. */
     old_cksum = hb_block->hb_cksum;
     hb_block->hb_cksum = 0;
 
     ret = crc32_le(0, (unsigned char *) hb_block, reg->hr_block_bytes);
 
     hb_block->hb_cksum = old_cksum;
 
     return ret;
 }
 
 static void o2hb_dump_slot(struct o2hb_disk_heartbeat_block *hb_block)
 {
     mlog(ML_ERROR, "Dump slot information: seq = 0x%llx, node = %u, "
          "cksum = 0x%x, generation 0x%llx\n",
          (long long)le64_to_cpu(hb_block->hb_seq),
          hb_block->hb_node, le32_to_cpu(hb_block->hb_cksum),
          (long long)le64_to_cpu(hb_block->hb_generation));
 }
 
 static int o2hb_verify_crc(struct o2hb_region *reg,
                struct o2hb_disk_heartbeat_block *hb_block)
 {
     u32 read, computed;
 
     read = le32_to_cpu(hb_block->hb_cksum);
     computed = o2hb_compute_block_crc_le(reg, hb_block);
 
     return read == computed;
 }
 
 /*
  * Compare the slot data with what we wrote in the last iteration.
  * If the match fails, print an appropriate error message. This is to
  * detect errors like... another node hearting on the same slot,
  * flaky device that is losing writes, etc.
  * Returns 1 if check succeeds, 0 otherwise.
  */
 static int o2hb_check_own_slot(struct o2hb_region *reg)
 {
     struct o2hb_disk_slot *slot;
     struct o2hb_disk_heartbeat_block *hb_block;
     char *errstr;
 
     slot = &reg->hr_slots[o2nm_this_node()];
     /* Don't check on our 1st timestamp */
     if (!slot->ds_last_time)
         return 0;
 
     hb_block = slot->ds_raw_block;
     if (le64_to_cpu(hb_block->hb_seq) == slot->ds_last_time &&
         le64_to_cpu(hb_block->hb_generation) == slot->ds_last_generation &&
         hb_block->hb_node == slot->ds_node_num)
         return 1;
 
 #define ERRSTR1     "Another node is heartbeating on device"
 #define ERRSTR2     "Heartbeat generation mismatch on device"
 #define ERRSTR3     "Heartbeat sequence mismatch on device"
 
     if (hb_block->hb_node != slot->ds_node_num)
         errstr = ERRSTR1;
     else if (le64_to_cpu(hb_block->hb_generation) !=
          slot->ds_last_generation)
         errstr = ERRSTR2;
     else
         errstr = ERRSTR3;
 
     mlog(ML_ERROR, "%s (%pg): expected(%u:0x%llx, 0x%llx), "
          "ondisk(%u:0x%llx, 0x%llx)\n", errstr, reg->hr_bdev,
          slot->ds_node_num, (unsigned long long)slot->ds_last_generation,
          (unsigned long long)slot->ds_last_time, hb_block->hb_node,
          (unsigned long long)le64_to_cpu(hb_block->hb_generation),
          (unsigned long long)le64_to_cpu(hb_block->hb_seq));
 
     return 0;
 }
 
 static inline void o2hb_prepare_block(struct o2hb_region *reg,
                       u64 generation)
 {
     int node_num;
     u64 cputime;
     struct o2hb_disk_slot *slot;
     struct o2hb_disk_heartbeat_block *hb_block;
 
     node_num = o2nm_this_node();
     slot = &reg->hr_slots[node_num];
 
     hb_block = (struct o2hb_disk_heartbeat_block *)slot->ds_raw_block;
     memset(hb_block, 0, reg->hr_block_bytes);
     /* TODO: time stuff */
     cputime = ktime_get_real_seconds();
     if (!cputime)
         cputime = 1;
 
     hb_block->hb_seq = cpu_to_le64(cputime);
     hb_block->hb_node = node_num;
     hb_block->hb_generation = cpu_to_le64(generation);
     hb_block->hb_dead_ms = cpu_to_le32(o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS);
 
     /* This step must always happen last! */
     hb_block->hb_cksum = cpu_to_le32(o2hb_compute_block_crc_le(reg,
                                    hb_block));
 
     mlog(ML_HB_BIO, "our node generation = 0x%llx, cksum = 0x%x\n",
          (long long)generation,
          le32_to_cpu(hb_block->hb_cksum));
 }
 
 static void o2hb_fire_callbacks(struct o2hb_callback *hbcall,
                 struct o2nm_node *node,
                 int idx)
 {
     struct o2hb_callback_func *f;
 
     list_for_each_entry(f, &hbcall->list, hc_item) {
         mlog(ML_HEARTBEAT, "calling funcs %p\n", f);
         (f->hc_func)(node, idx, f->hc_data);
     }
 }
 
 /* Will run the list in order until we process the passed event */
 static void o2hb_run_event_list(struct o2hb_node_event *queued_event)
 {
     struct o2hb_callback *hbcall;
     struct o2hb_node_event *event;
 
     /* Holding callback sem assures we don't alter the callback
      * lists when doing this, and serializes ourselves with other
      * processes wanting callbacks. */
     down_write(&o2hb_callback_sem);
 
     spin_lock(&o2hb_live_lock);
     while (!list_empty(&o2hb_node_events)
            && !list_empty(&queued_event->hn_item)) {
         event = list_entry(o2hb_node_events.next,
                    struct o2hb_node_event,
                    hn_item);
         list_del_init(&event->hn_item);
         spin_unlock(&o2hb_live_lock);
 
         mlog(ML_HEARTBEAT, "Node %s event for %d\n",
              event->hn_event_type == O2HB_NODE_UP_CB ? "UP" : "DOWN",
              event->hn_node_num);
 
         hbcall = hbcall_from_type(event->hn_event_type);
 
         /* We should *never* have gotten on to the list with a
          * bad type... This isn't something that we should try
          * to recover from. */
         BUG_ON(IS_ERR(hbcall));
 
         o2hb_fire_callbacks(hbcall, event->hn_node, event->hn_node_num);
 
         spin_lock(&o2hb_live_lock);
     }
     spin_unlock(&o2hb_live_lock);
 
     up_write(&o2hb_callback_sem);
 }
 
 static void o2hb_queue_node_event(struct o2hb_node_event *event,
                   enum o2hb_callback_type type,
                   struct o2nm_node *node,
                   int node_num)
 {
     assert_spin_locked(&o2hb_live_lock);
 
     BUG_ON((!node) && (type != O2HB_NODE_DOWN_CB));
 
     event->hn_event_type = type;
     event->hn_node = node;
     event->hn_node_num = node_num;
 
     mlog(ML_HEARTBEAT, "Queue node %s event for node %d\n",
          type == O2HB_NODE_UP_CB ? "UP" : "DOWN", node_num);
 
     list_add_tail(&event->hn_item, &o2hb_node_events);
 }
 
 static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
 {
     struct o2hb_node_event event =
         { .hn_item = LIST_HEAD_INIT(event.hn_item), };
     struct o2nm_node *node;
     int queued = 0;
 
     node = o2nm_get_node_by_num(slot->ds_node_num);
     if (!node)
         return;
 
     spin_lock(&o2hb_live_lock);
     if (!list_empty(&slot->ds_live_item)) {
         mlog(ML_HEARTBEAT, "Shutdown, node %d leaves region\n",
              slot->ds_node_num);
 
         list_del_init(&slot->ds_live_item);
 
         if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
             clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);
 
             o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
                           slot->ds_node_num);
             queued = 1;
         }
     }
     spin_unlock(&o2hb_live_lock);
 
     if (queued)
         o2hb_run_event_list(&event);
 
     o2nm_node_put(node);
 }
 
 static void o2hb_set_quorum_device(struct o2hb_region *reg)
 {
     if (!o2hb_global_heartbeat_active())
         return;
 
     /* Prevent race with o2hb_heartbeat_group_drop_item() */
     if (kthread_should_stop())
         return;
 
     /* Tag region as quorum only after thread reaches steady state */
     if (atomic_read(&reg->hr_steady_iterations) != 0)
         return;
 
     spin_lock(&o2hb_live_lock);
 
     if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
         goto unlock;
 
     /*
      * A region can be added to the quorum only when it sees all
      * live nodes heartbeat on it. In other words, the region has been
      * added to all nodes.
      */
     if (memcmp(reg->hr_live_node_bitmap, o2hb_live_node_bitmap,
            sizeof(o2hb_live_node_bitmap)))
         goto unlock;
 
     printk(KERN_NOTICE "o2hb: Region %s (%pg) is now a quorum device\n",
            config_item_name(&reg->hr_item), reg->hr_bdev);
 
     set_bit(reg->hr_region_num, o2hb_quorum_region_bitmap);
 
     /*
      * If global heartbeat active, unpin all regions if the
      * region count > CUT_OFF
      */
     if (bitmap_weight(o2hb_quorum_region_bitmap,
                O2NM_MAX_REGIONS) > O2HB_PIN_CUT_OFF)
         o2hb_region_unpin(NULL);
 unlock:
     spin_unlock(&o2hb_live_lock);
 }
 
 static int o2hb_check_slot(struct o2hb_region *reg,
                struct o2hb_disk_slot *slot)
 {
     int changed = 0, gen_changed = 0;
     struct o2hb_node_event event =
         { .hn_item = LIST_HEAD_INIT(event.hn_item), };
     struct o2nm_node *node;
     struct o2hb_disk_heartbeat_block *hb_block = reg->hr_tmp_block;
     u64 cputime;
     unsigned int dead_ms = o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS;
     unsigned int slot_dead_ms;
     int tmp;
     int queued = 0;
 
     memcpy(hb_block, slot->ds_raw_block, reg->hr_block_bytes);
 
     /*
      * If a node is no longer configured but is still in the livemap, we
      * may need to clear that bit from the livemap.
      */
     node = o2nm_get_node_by_num(slot->ds_node_num);
     if (!node) {
         spin_lock(&o2hb_live_lock);
         tmp = test_bit(slot->ds_node_num, o2hb_live_node_bitmap);
         spin_unlock(&o2hb_live_lock);
         if (!tmp)
             return 0;
     }
 
     if (!o2hb_verify_crc(reg, hb_block)) {
         /* all paths from here will drop o2hb_live_lock for
          * us. */
         spin_lock(&o2hb_live_lock);
 
         /* Don't print an error on the console in this case -
          * a freshly formatted heartbeat area will not have a
          * crc set on it. */
         if (list_empty(&slot->ds_live_item))
             goto out;
 
         /* The node is live but pushed out a bad crc. We
          * consider it a transient miss but don't populate any
          * other values as they may be junk. */
         mlog(ML_ERROR, "Node %d has written a bad crc to %pg\n",
              slot->ds_node_num, reg->hr_bdev);
         o2hb_dump_slot(hb_block);
 
         slot->ds_equal_samples++;
         goto fire_callbacks;
     }
 
     /* we don't care if these wrap.. the state transitions below
      * clear at the right places */
     cputime = le64_to_cpu(hb_block->hb_seq);
     if (slot->ds_last_time != cputime)
         slot->ds_changed_samples++;
     else
         slot->ds_equal_samples++;
     slot->ds_last_time = cputime;
 
     /* The node changed heartbeat generations. We assume this to
      * mean it dropped off but came back before we timed out. We
      * want to consider it down for the time being but don't want
      * to lose any changed_samples state we might build up to
      * considering it live again. */
     if (slot->ds_last_generation != le64_to_cpu(hb_block->hb_generation)) {
         gen_changed = 1;
         slot->ds_equal_samples = 0;
         mlog(ML_HEARTBEAT, "Node %d changed generation (0x%llx "
              "to 0x%llx)\n", slot->ds_node_num,
              (long long)slot->ds_last_generation,
              (long long)le64_to_cpu(hb_block->hb_generation));
     }
 
     slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);
 
     mlog(ML_HEARTBEAT, "Slot %d gen 0x%llx cksum 0x%x "
          "seq %llu last %llu changed %u equal %u\n",
          slot->ds_node_num, (long long)slot->ds_last_generation,
          le32_to_cpu(hb_block->hb_cksum),
          (unsigned long long)le64_to_cpu(hb_block->hb_seq),
          (unsigned long long)slot->ds_last_time, slot->ds_changed_samples,
          slot->ds_equal_samples);
 
     spin_lock(&o2hb_live_lock);
 
 fire_callbacks:
     /* dead nodes only come to life after some number of
      * changes at any time during their dead time */
     if (list_empty(&slot->ds_live_item) &&
         slot->ds_changed_samples >= O2HB_LIVE_THRESHOLD) {
         mlog(ML_HEARTBEAT, "Node %d (id 0x%llx) joined my region\n",
              slot->ds_node_num, (long long)slot->ds_last_generation);
 
         set_bit(slot->ds_node_num, reg->hr_live_node_bitmap);
 
         /* first on the list generates a callback */
         if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
             mlog(ML_HEARTBEAT, "o2hb: Add node %d to live nodes "
                  "bitmap\n", slot->ds_node_num);
             set_bit(slot->ds_node_num, o2hb_live_node_bitmap);
 
             o2hb_queue_node_event(&event, O2HB_NODE_UP_CB, node,
                           slot->ds_node_num);
 
             changed = 1;
             queued = 1;
         }
 
         list_add_tail(&slot->ds_live_item,
                   &o2hb_live_slots[slot->ds_node_num]);
 
         slot->ds_equal_samples = 0;
 
         /* We want to be sure that all nodes agree on the
          * number of milliseconds before a node will be
          * considered dead. The self-fencing timeout is
          * computed from this value, and a discrepancy might
          * result in heartbeat calling a node dead when it
          * hasn't self-fenced yet. */
         slot_dead_ms = le32_to_cpu(hb_block->hb_dead_ms);
         if (slot_dead_ms && slot_dead_ms != dead_ms) {
             /* TODO: Perhaps we can fail the region here. */
             mlog(ML_ERROR, "Node %d on device %pg has a dead count "
                  "of %u ms, but our count is %u ms.\n"
                  "Please double check your configuration values "
                  "for 'O2CB_HEARTBEAT_THRESHOLD'\n",
                  slot->ds_node_num, reg->hr_bdev, slot_dead_ms,
                  dead_ms);
         }
         goto out;
     }
 
     /* if the list is dead, we're done.. */
     if (list_empty(&slot->ds_live_item))
         goto out;
 
     /* live nodes only go dead after enough consequtive missed
      * samples..  reset the missed counter whenever we see
      * activity */
     if (slot->ds_equal_samples >= o2hb_dead_threshold || gen_changed) {
         mlog(ML_HEARTBEAT, "Node %d left my region\n",
              slot->ds_node_num);
 
         clear_bit(slot->ds_node_num, reg->hr_live_node_bitmap);
 
         /* last off the live_slot generates a callback */
         list_del_init(&slot->ds_live_item);
         if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
             mlog(ML_HEARTBEAT, "o2hb: Remove node %d from live "
                  "nodes bitmap\n", slot->ds_node_num);
             clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);
 
             /* node can be null */
             o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB,
                           node, slot->ds_node_num);
 
             changed = 1;
             queued = 1;
         }
 
         /* We don't clear this because the node is still
          * actually writing new blocks. */
         if (!gen_changed)
             slot->ds_changed_samples = 0;
         goto out;
     }
     if (slot->ds_changed_samples) {
         slot->ds_changed_samples = 0;
         slot->ds_equal_samples = 0;
     }
 out:
     spin_unlock(&o2hb_live_lock);
 
     if (queued)
         o2hb_run_event_list(&event);
 
     if (node)
         o2nm_node_put(node);
     return changed;
 }
 
 static int o2hb_highest_node(unsigned long *nodes, int numbits)
 {
     return find_last_bit(nodes, numbits);
 }
 
 static int o2hb_lowest_node(unsigned long *nodes, int numbits)
 {
     return find_first_bit(nodes, numbits);
 }
 
 static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 {
     int i, ret, highest_node, lowest_node;
     int membership_change = 0, own_slot_ok = 0;
     unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
     unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
     struct o2hb_bio_wait_ctxt write_wc;
 
     ret = o2nm_configured_node_map(configured_nodes,
                        sizeof(configured_nodes));
     if (ret) {
         mlog_errno(ret);
         goto bail;
     }
 
     /*
      * If a node is not configured but is in the livemap, we still need
      * to read the slot so as to be able to remove it from the livemap.
      */
     o2hb_fill_node_map(live_node_bitmap, sizeof(live_node_bitmap));
     i = -1;
     while ((i = find_next_bit(live_node_bitmap,
                   O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
         set_bit(i, configured_nodes);
     }
 
     highest_node = o2hb_highest_node(configured_nodes, O2NM_MAX_NODES);
     lowest_node = o2hb_lowest_node(configured_nodes, O2NM_MAX_NODES);
     if (highest_node >= O2NM_MAX_NODES || lowest_node >= O2NM_MAX_NODES) {
         mlog(ML_NOTICE, "o2hb: No configured nodes found!\n");
         ret = -EINVAL;
         goto bail;
     }
 
     /* No sense in reading the slots of nodes that don't exist
      * yet. Of course, if the node definitions have holes in them
      * then we're reading an empty slot anyway... Consider this
      * best-effort. */
     ret = o2hb_read_slots(reg, lowest_node, highest_node + 1);
     if (ret < 0) {
         mlog_errno(ret);
         goto bail;
     }
 
     /* With an up to date view of the slots, we can check that no
      * other node has been improperly configured to heartbeat in
      * our slot. */
     own_slot_ok = o2hb_check_own_slot(reg);
 
     /* fill in the proper info for our next heartbeat */
     o2hb_prepare_block(reg, reg->hr_generation);
 
     ret = o2hb_issue_node_write(reg, &write_wc);
     if (ret < 0) {
         mlog_errno(ret);
         goto bail;
     }
 
     i = -1;
     while((i = find_next_bit(configured_nodes,
                  O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
         membership_change |= o2hb_check_slot(reg, &reg->hr_slots[i]);
     }
 
     /*
      * We have to be sure we've advertised ourselves on disk
      * before we can go to steady state.  This ensures that
      * people we find in our steady state have seen us.
      */
     o2hb_wait_on_io(&write_wc);
     if (write_wc.wc_error) {
         /* Do not re-arm the write timeout on I/O error - we
          * can't be sure that the new block ever made it to
          * disk */
         mlog(ML_ERROR, "Write error %d on device \"%pg\"\n",
              write_wc.wc_error, reg->hr_bdev);
         ret = write_wc.wc_error;
         goto bail;
     }
 
     /* Skip disarming the timeout if own slot has stale/bad data */
     if (own_slot_ok) {
         o2hb_set_quorum_device(reg);
         o2hb_arm_timeout(reg);
         reg->hr_last_timeout_start = jiffies;
     }
 
 bail:
     /* let the person who launched us know when things are steady */
     if (atomic_read(&reg->hr_steady_iterations) != 0) {
         if (!ret && own_slot_ok && !membership_change) {
             if (atomic_dec_and_test(&reg->hr_steady_iterations))
                 wake_up(&o2hb_steady_queue);
         }
     }
 
     if (atomic_read(&reg->hr_steady_iterations) != 0) {
         if (atomic_dec_and_test(&reg->hr_unsteady_iterations)) {
             printk(KERN_NOTICE "o2hb: Unable to stabilize "
                    "heartbeat on region %s (%pg)\n",
                    config_item_name(&reg->hr_item),
                    reg->hr_bdev);
             atomic_set(&reg->hr_steady_iterations, 0);
             reg->hr_aborted_start = 1;
             wake_up(&o2hb_steady_queue);
             ret = -EIO;
         }
     }
 
     return ret;
 }
 
 /*
  * we ride the region ref that the region dir holds.  before the region
  * dir is removed and drops it ref it will wait to tear down this
  * thread.
  */
 static int o2hb_thread(void *data)
 {
     int i, ret;
     struct o2hb_region *reg = data;
     struct o2hb_bio_wait_ctxt write_wc;
     ktime_t before_hb, after_hb;
     unsigned int elapsed_msec;
 
     mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread running\n");
 
     set_user_nice(current, MIN_NICE);
 
     /* Pin node */
     ret = o2nm_depend_this_node();
     if (ret) {
         mlog(ML_ERROR, "Node has been deleted, ret = %d\n", ret);
         reg->hr_node_deleted = 1;
         wake_up(&o2hb_steady_queue);
         return 0;
     }
 
     while (!kthread_should_stop() &&
            !reg->hr_unclean_stop && !reg->hr_aborted_start) {
         /* We track the time spent inside
          * o2hb_do_disk_heartbeat so that we avoid more than
          * hr_timeout_ms between disk writes. On busy systems
          * this should result in a heartbeat which is less
          * likely to time itself out. */
         before_hb = ktime_get_real();
 
         ret = o2hb_do_disk_heartbeat(reg);
         reg->hr_last_hb_status = ret;
 
         after_hb = ktime_get_real();
 
         elapsed_msec = (unsigned int)
                 ktime_ms_delta(after_hb, before_hb);
 
         mlog(ML_HEARTBEAT,
              "start = %lld, end = %lld, msec = %u, ret = %d\n",
              before_hb, after_hb, elapsed_msec, ret);
 
         if (!kthread_should_stop() &&
             elapsed_msec < reg->hr_timeout_ms) {
             /* the kthread api has blocked signals for us so no
              * need to record the return value. */
             msleep_interruptible(reg->hr_timeout_ms - elapsed_msec);
         }
     }
 
     o2hb_disarm_timeout(reg);
 
     /* unclean stop is only used in very bad situation */
     for(i = 0; !reg->hr_unclean_stop && i < reg->hr_blocks; i++)
         o2hb_shutdown_slot(&reg->hr_slots[i]);
 
     /* Explicit down notification - avoid forcing the other nodes
      * to timeout on this region when we could just as easily
      * write a clear generation - thus indicating to them that
      * this node has left this region.
      */
     if (!reg->hr_unclean_stop && !reg->hr_aborted_start) {
         o2hb_prepare_block(reg, 0);
         ret = o2hb_issue_node_write(reg, &write_wc);
         if (ret == 0)
             o2hb_wait_on_io(&write_wc);
         else
             mlog_errno(ret);
     }
 
     /* Unpin node */
     o2nm_undepend_this_node();
 
     mlog(ML_HEARTBEAT|ML_KTHREAD, "o2hb thread exiting\n");
 
     return 0;
 }
 
 #ifdef CONFIG_DEBUG_FS
 static int o2hb_debug_open(struct inode *inode, struct file *file)
 {
     struct o2hb_debug_buf *db = inode->i_private;
     struct o2hb_region *reg;
     unsigned long map[BITS_TO_LONGS(O2NM_MAX_NODES)];
     unsigned long lts;
     char *buf = NULL;
     int i = -1;
     int out = 0;
 
     /* max_nodes should be the largest bitmap we pass here */
     BUG_ON(sizeof(map) < db->db_size);
 
     buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
     if (!buf)
         goto bail;
 
     switch (db->db_type) {
     case O2HB_DB_TYPE_LIVENODES:
     case O2HB_DB_TYPE_LIVEREGIONS:
     case O2HB_DB_TYPE_QUORUMREGIONS:
     case O2HB_DB_TYPE_FAILEDREGIONS:
         spin_lock(&o2hb_live_lock);
         memcpy(map, db->db_data, db->db_size);
         spin_unlock(&o2hb_live_lock);
         break;
 
     case O2HB_DB_TYPE_REGION_LIVENODES:
         spin_lock(&o2hb_live_lock);
         reg = (struct o2hb_region *)db->db_data;
         memcpy(map, reg->hr_live_node_bitmap, db->db_size);
         spin_unlock(&o2hb_live_lock);
         break;
 
     case O2HB_DB_TYPE_REGION_NUMBER:
         reg = (struct o2hb_region *)db->db_data;
         out += scnprintf(buf + out, PAGE_SIZE - out, "%d\n",
                 reg->hr_region_num);
         goto done;
 
     case O2HB_DB_TYPE_REGION_ELAPSED_TIME:
         reg = (struct o2hb_region *)db->db_data;
         lts = reg->hr_last_timeout_start;
         /* If 0, it has never been set before */
         if (lts)
             lts = jiffies_to_msecs(jiffies - lts);
         out += scnprintf(buf + out, PAGE_SIZE - out, "%lu\n", lts);
         goto done;
 
     case O2HB_DB_TYPE_REGION_PINNED:
         reg = (struct o2hb_region *)db->db_data;
         out += scnprintf(buf + out, PAGE_SIZE - out, "%u\n",
                 !!reg->hr_item_pinned);
         goto done;
 
     default:
         goto done;
     }
 
     while ((i = find_next_bit(map, db->db_len, i + 1)) < db->db_len)
         out += scnprintf(buf + out, PAGE_SIZE - out, "%d ", i);
     out += scnprintf(buf + out, PAGE_SIZE - out, "\n");
 
 done:
     i_size_write(inode, out);
 
     file->private_data = buf;
 
     return 0;
 bail:
     return -ENOMEM;
 }
 
 static int o2hb_debug_release(struct inode *inode, struct file *file)
 {
     kfree(file->private_data);
     return 0;
 }
 
 static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
                  size_t nbytes, loff_t *ppos)
 {
     return simple_read_from_buffer(buf, nbytes, ppos, file->private_data,
                        i_size_read(file->f_mapping->host));
 }
 #else
 static int o2hb_debug_open(struct inode *inode, struct file *file)
 {
     return 0;
 }
 static int o2hb_debug_release(struct inode *inode, struct file *file)
 {
     return 0;
 }
 static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
                    size_t nbytes, loff_t *ppos)
 {
     return 0;
 }
 #endif  /* CONFIG_DEBUG_FS */
 
 static const struct file_operations o2hb_debug_fops = {
     .open =     o2hb_debug_open,
     .release =  o2hb_debug_release,
     .read =     o2hb_debug_read,
     .llseek =   generic_file_llseek,
 };
 
 void o2hb_exit(void)
 {
     debugfs_remove_recursive(o2hb_debug_dir);
     kfree(o2hb_db_livenodes);
     kfree(o2hb_db_liveregions);
     kfree(o2hb_db_quorumregions);
     kfree(o2hb_db_failedregions);
 }
 
 static void o2hb_debug_create(const char *name, struct dentry *dir,
                   struct o2hb_debug_buf **db, int db_len, int type,
                   int size, int len, void *data)
 {
     *db = kmalloc(db_len, GFP_KERNEL);
     if (!*db)
         return;
 
     (*db)->db_type = type;
     (*db)->db_size = size;
     (*db)->db_len = len;
     (*db)->db_data = data;
 
     debugfs_create_file(name, S_IFREG|S_IRUSR, dir, *db, &o2hb_debug_fops);
 }
 
 static void o2hb_debug_init(void)
 {
     o2hb_debug_dir = debugfs_create_dir(O2HB_DEBUG_DIR, NULL);
 
     o2hb_debug_create(O2HB_DEBUG_LIVENODES, o2hb_debug_dir,
               &o2hb_db_livenodes, sizeof(*o2hb_db_livenodes),
               O2HB_DB_TYPE_LIVENODES, sizeof(o2hb_live_node_bitmap),
               O2NM_MAX_NODES, o2hb_live_node_bitmap);
 
     o2hb_debug_create(O2HB_DEBUG_LIVEREGIONS, o2hb_debug_dir,
               &o2hb_db_liveregions, sizeof(*o2hb_db_liveregions),
               O2HB_DB_TYPE_LIVEREGIONS,
               sizeof(o2hb_live_region_bitmap), O2NM_MAX_REGIONS,
               o2hb_live_region_bitmap);
 
     o2hb_debug_create(O2HB_DEBUG_QUORUMREGIONS, o2hb_debug_dir,
               &o2hb_db_quorumregions,
               sizeof(*o2hb_db_quorumregions),
               O2HB_DB_TYPE_QUORUMREGIONS,
               sizeof(o2hb_quorum_region_bitmap), O2NM_MAX_REGIONS,
               o2hb_quorum_region_bitmap);
 
     o2hb_debug_create(O2HB_DEBUG_FAILEDREGIONS, o2hb_debug_dir,
               &o2hb_db_failedregions,
               sizeof(*o2hb_db_failedregions),
               O2HB_DB_TYPE_FAILEDREGIONS,
               sizeof(o2hb_failed_region_bitmap), O2NM_MAX_REGIONS,
               o2hb_failed_region_bitmap);
 }
 
 void o2hb_init(void)
 {
     int i;
 
     for (i = 0; i < ARRAY_SIZE(o2hb_callbacks); i++)
         INIT_LIST_HEAD(&o2hb_callbacks[i].list);
 
     for (i = 0; i < ARRAY_SIZE(o2hb_live_slots); i++)
         INIT_LIST_HEAD(&o2hb_live_slots[i]);
 
     memset(o2hb_live_node_bitmap, 0, sizeof(o2hb_live_node_bitmap));
     memset(o2hb_region_bitmap, 0, sizeof(o2hb_region_bitmap));
     memset(o2hb_live_region_bitmap, 0, sizeof(o2hb_live_region_bitmap));
     memset(o2hb_quorum_region_bitmap, 0, sizeof(o2hb_quorum_region_bitmap));
     memset(o2hb_failed_region_bitmap, 0, sizeof(o2hb_failed_region_bitmap));
 
     o2hb_dependent_users = 0;
 
     o2hb_debug_init();
 }
 
 /* if we're already in a callback then we're already serialized by the sem */
 static void o2hb_fill_node_map_from_callback(unsigned long *map,
                          unsigned bytes)
 {
     BUG_ON(bytes < (BITS_TO_LONGS(O2NM_MAX_NODES) * sizeof(unsigned long)));
 
     memcpy(map, &o2hb_live_node_bitmap, bytes);
 }
 
 /*
  * get a map of all nodes that are heartbeating in any regions
  */
 void o2hb_fill_node_map(unsigned long *map, unsigned bytes)
 {
     /* callers want to serialize this map and callbacks so that they
      * can trust that they don't miss nodes coming to the party */
     down_read(&o2hb_callback_sem);
     spin_lock(&o2hb_live_lock);
     o2hb_fill_node_map_from_callback(map, bytes);
     spin_unlock(&o2hb_live_lock);
     up_read(&o2hb_callback_sem);
 }
 EXPORT_SYMBOL_GPL(o2hb_fill_node_map);
 
 /*
  * heartbeat configfs bits.  The heartbeat set is a default set under
  * the cluster set in nodemanager.c.
  */
 
 static struct o2hb_region *to_o2hb_region(struct config_item *item)
 {
     return item ? container_of(item, struct o2hb_region, hr_item) : NULL;
 }
 
 /* drop_item only drops its ref after killing the thread, nothing should
  * be using the region anymore.  this has to clean up any state that
  * attributes might have built up. */
 static void o2hb_region_release(struct config_item *item)
 {
     int i;
     struct page *page;
     struct o2hb_region *reg = to_o2hb_region(item);
 
     mlog(ML_HEARTBEAT, "hb region release (%pg)\n", reg->hr_bdev);
 
     kfree(reg->hr_tmp_block);
 
     if (reg->hr_slot_data) {
         for (i = 0; i < reg->hr_num_pages; i++) {
             page = reg->hr_slot_data[i];
             if (page)
                 __free_page(page);
         }
         kfree(reg->hr_slot_data);
     }
 
     if (reg->hr_bdev)
         blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
 
     kfree(reg->hr_slots);
 
     debugfs_remove_recursive(reg->hr_debug_dir);
     kfree(reg->hr_db_livenodes);
     kfree(reg->hr_db_regnum);
     kfree(reg->hr_db_elapsed_time);
     kfree(reg->hr_db_pinned);
 
     spin_lock(&o2hb_live_lock);
     list_del(&reg->hr_all_item);
     spin_unlock(&o2hb_live_lock);
 
     o2net_unregister_handler_list(&reg->hr_handler_list);
     kfree(reg);
 }
 
 static int o2hb_read_block_input(struct o2hb_region *reg,
                  const char *page,
                  unsigned long *ret_bytes,
                  unsigned int *ret_bits)
 {
     unsigned long bytes;
     char *p = (char *)page;
 
     bytes = simple_strtoul(p, &p, 0);
     if (!p || (*p && (*p != '\n')))
         return -EINVAL;
 
     /* Heartbeat and fs min / max block sizes are the same. */
     if (bytes > 4096 || bytes < 512)
         return -ERANGE;
     if (hweight16(bytes) != 1)
         return -EINVAL;
 
     if (ret_bytes)
         *ret_bytes = bytes;
     if (ret_bits)
         *ret_bits = ffs(bytes) - 1;
 
     return 0;
 }
 
 static ssize_t o2hb_region_block_bytes_show(struct config_item *item,
                         char *page)
 {
     return sprintf(page, "%u\n", to_o2hb_region(item)->hr_block_bytes);
 }
 
 static ssize_t o2hb_region_block_bytes_store(struct config_item *item,
                          const char *page,
                          size_t count)
 {
     struct o2hb_region *reg = to_o2hb_region(item);
     int status;
     unsigned long block_bytes;
     unsigned int block_bits;
 
     if (reg->hr_bdev)
         return -EINVAL;
 
     status = o2hb_read_block_input(reg, page, &block_bytes,
                        &block_bits);
     if (status)
         return status;
 
     reg->hr_block_bytes = (unsigned int)block_bytes;
     reg->hr_block_bits = block_bits;
 
     return count;
 }
 
 static ssize_t o2hb_region_start_block_show(struct config_item *item,
                         char *page)
 {
     return sprintf(page, "%llu\n", to_o2hb_region(item)->hr_start_block);
 }
 
 static ssize_t o2hb_region_start_block_store(struct config_item *item,
                          const char *page,
                          size_t count)
 {
     struct o2hb_region *reg = to_o2hb_region(item);
     unsigned long long tmp;
     char *p = (char *)page;
     ssize_t ret;
 
     if (reg->hr_bdev)
         return -EINVAL;
 
     ret = kstrtoull(p, 0, &tmp);
     if (ret)
         return -EINVAL;
 
     reg->hr_start_block = tmp;
 
     return count;
 }
 
 static ssize_t o2hb_region_blocks_show(struct config_item *item, char *page)
 {
     return sprintf(page, "%d\n", to_o2hb_region(item)->hr_blocks);
 }
 
 static ssize_t o2hb_region_blocks_store(struct config_item *item,
                     const char *page,
                     size_t count)
 {
     struct o2hb_region *reg = to_o2hb_region(item);
     unsigned long tmp;
     char *p = (char *)page;
 
     if (reg->hr_bdev)
         return -EINVAL;
 
     tmp = simple_strtoul(p, &p, 0);
     if (!p || (*p && (*p != '\n')))
         return -EINVAL;
 
     if (tmp > O2NM_MAX_NODES || tmp == 0)
         return -ERANGE;
 
     reg->hr_blocks = (unsigned int)tmp;
 
     return count;
 }
 
 static ssize_t o2hb_region_dev_show(struct config_item *item, char *page)
 {
     unsigned int ret = 0;
 
     if (to_o2hb_region(item)->hr_bdev)
         ret = sprintf(page, "%pg\n", to_o2hb_region(item)->hr_bdev);
 
     return ret;
 }
 
 static void o2hb_init_region_params(struct o2hb_region *reg)
 {
     reg->hr_slots_per_page = PAGE_SIZE >> reg->hr_block_bits;
     reg->hr_timeout_ms = O2HB_REGION_TIMEOUT_MS;
 
     mlog(ML_HEARTBEAT, "hr_start_block = %llu, hr_blocks = %u\n",
          reg->hr_start_block, reg->hr_blocks);
     mlog(ML_HEARTBEAT, "hr_block_bytes = %u, hr_block_bits = %u\n",
          reg->hr_block_bytes, reg->hr_block_bits);
     mlog(ML_HEARTBEAT, "hr_timeout_ms = %u\n", reg->hr_timeout_ms);
     mlog(ML_HEARTBEAT, "dead threshold = %u\n", o2hb_dead_threshold);
 }
 
 static int o2hb_map_slot_data(struct o2hb_region *reg)
 {
     int i, j;
     unsigned int last_slot;
     unsigned int spp = reg->hr_slots_per_page;
     struct page *page;
     char *raw;
     struct o2hb_disk_slot *slot;
 
     reg->hr_tmp_block = kmalloc(reg->hr_block_bytes, GFP_KERNEL);
     if (reg->hr_tmp_block == NULL)
         return -ENOMEM;
 
     reg->hr_slots = kcalloc(reg->hr_blocks,
                 sizeof(struct o2hb_disk_slot), GFP_KERNEL);
     if (reg->hr_slots == NULL)
         return -ENOMEM;
 
     for(i = 0; i < reg->hr_blocks; i++) {
         slot = &reg->hr_slots[i];
         slot->ds_node_num = i;
         INIT_LIST_HEAD(&slot->ds_live_item);
         slot->ds_raw_block = NULL;
     }
 
     reg->hr_num_pages = (reg->hr_blocks + spp - 1) / spp;
     mlog(ML_HEARTBEAT, "Going to require %u pages to cover %u blocks "
                "at %u blocks per page\n",
          reg->hr_num_pages, reg->hr_blocks, spp);
 
     reg->hr_slot_data = kcalloc(reg->hr_num_pages, sizeof(struct page *),
                     GFP_KERNEL);
     if (!reg->hr_slot_data)
         return -ENOMEM;
 
     for(i = 0; i < reg->hr_num_pages; i++) {
         page = alloc_page(GFP_KERNEL);
         if (!page)
             return -ENOMEM;
 
         reg->hr_slot_data[i] = page;
 
         last_slot = i * spp;
         raw = page_address(page);
         for (j = 0;
              (j < spp) && ((j + last_slot) < reg->hr_blocks);
              j++) {
             BUG_ON((j + last_slot) >= reg->hr_blocks);
 
             slot = &reg->hr_slots[j + last_slot];
             slot->ds_raw_block =
                 (struct o2hb_disk_heartbeat_block *) raw;
 
             raw += reg->hr_block_bytes;
         }
     }
 
     return 0;
 }
 
 /* Read in all the slots available and populate the tracking
  * structures so that we can start with a baseline idea of what's
  * there. */
 static int o2hb_populate_slot_data(struct o2hb_region *reg)
 {
     int ret, i;
     struct o2hb_disk_slot *slot;
     struct o2hb_disk_heartbeat_block *hb_block;
 
     ret = o2hb_read_slots(reg, 0, reg->hr_blocks);
     if (ret)
         goto out;
 
     /* We only want to get an idea of the values initially in each
      * slot, so we do no verification - o2hb_check_slot will
      * actually determine if each configured slot is valid and
      * whether any values have changed. */
     for(i = 0; i < reg->hr_blocks; i++) {
         slot = &reg->hr_slots[i];
         hb_block = (struct o2hb_disk_heartbeat_block *) slot->ds_raw_block;
 
         /* Only fill the values that o2hb_check_slot uses to
          * determine changing slots */
         slot->ds_last_time = le64_to_cpu(hb_block->hb_seq);
         slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);
     }
 
 out:
     return ret;
 }
 
 /* this is acting as commit; we set up all of hr_bdev and hr_task or nothing */
 static ssize_t o2hb_region_dev_store(struct config_item *item,
                      const char *page,
                      size_t count)
 {
     struct o2hb_region *reg = to_o2hb_region(item);
     struct task_struct *hb_task;
     long fd;
     int sectsize;
     char *p = (char *)page;
     struct fd f;
     ssize_t ret = -EINVAL;
     int live_threshold;
 
     if (reg->hr_bdev)
         goto out;
 
     /* We can't heartbeat without having had our node number
      * configured yet. */
     if (o2nm_this_node() == O2NM_MAX_NODES)
         goto out;
 
     fd = simple_strtol(p, &p, 0);
     if (!p || (*p && (*p != '\n')))
         goto out;
 
     if (fd < 0 || fd >= INT_MAX)
         goto out;
 
     f = fdget(fd);
     if (f.file == NULL)
         goto out;
 
     if (reg->hr_blocks == 0 || reg->hr_start_block == 0 ||
         reg->hr_block_bytes == 0)
         goto out2;
 
     if (!S_ISBLK(f.file->f_mapping->host->i_mode))
         goto out2;
 
     reg->hr_bdev = blkdev_get_by_dev(f.file->f_mapping->host->i_rdev,
                      FMODE_WRITE | FMODE_READ, NULL);
     if (IS_ERR(reg->hr_bdev)) {
         ret = PTR_ERR(reg->hr_bdev);
         reg->hr_bdev = NULL;
         goto out2;
     }
 
     sectsize = bdev_logical_block_size(reg->hr_bdev);
     if (sectsize != reg->hr_block_bytes) {
         mlog(ML_ERROR,
              "blocksize %u incorrect for device, expected %d",
              reg->hr_block_bytes, sectsize);
         ret = -EINVAL;
         goto out3;
     }
 
     o2hb_init_region_params(reg);
 
     /* Generation of zero is invalid */
     do {
         get_random_bytes(&reg->hr_generation,
                  sizeof(reg->hr_generation));
     } while (reg->hr_generation == 0);
 
     ret = o2hb_map_slot_data(reg);
     if (ret) {
         mlog_errno(ret);
         goto out3;
     }
 
     ret = o2hb_populate_slot_data(reg);
     if (ret) {
         mlog_errno(ret);
         goto out3;
     }
 
     INIT_DELAYED_WORK(&reg->hr_write_timeout_work, o2hb_write_timeout);
     INIT_DELAYED_WORK(&reg->hr_nego_timeout_work, o2hb_nego_timeout);
 
     /*
      * A node is considered live after it has beat LIVE_THRESHOLD
      * times.  We're not steady until we've given them a chance
      * _after_ our first read.
      * The default threshold is bare minimum so as to limit the delay
      * during mounts. For global heartbeat, the threshold doubled for the
      * first region.
      */
     live_threshold = O2HB_LIVE_THRESHOLD;
     if (o2hb_global_heartbeat_active()) {
         spin_lock(&o2hb_live_lock);
         if (bitmap_weight(o2hb_region_bitmap, O2NM_MAX_REGIONS) == 1)
             live_threshold <<= 1;
         spin_unlock(&o2hb_live_lock);
     }
     ++live_threshold;
     atomic_set(&reg->hr_steady_iterations, live_threshold);
     /* unsteady_iterations is triple the steady_iterations */
     atomic_set(&reg->hr_unsteady_iterations, (live_threshold * 3));
 
     hb_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
                   reg->hr_item.ci_name);
     if (IS_ERR(hb_task)) {
         ret = PTR_ERR(hb_task);
         mlog_errno(ret);
         goto out3;
     }
 
     spin_lock(&o2hb_live_lock);
     reg->hr_task = hb_task;
     spin_unlock(&o2hb_live_lock);
 
     ret = wait_event_interruptible(o2hb_steady_queue,
                 atomic_read(&reg->hr_steady_iterations) == 0 ||
                 reg->hr_node_deleted);
     if (ret) {
         atomic_set(&reg->hr_steady_iterations, 0);
         reg->hr_aborted_start = 1;
     }
 
     if (reg->hr_aborted_start) {
         ret = -EIO;
         goto out3;
     }
 
     if (reg->hr_node_deleted) {
         ret = -EINVAL;
         goto out3;
     }
 
     /* Ok, we were woken.  Make sure it wasn't by drop_item() */
     spin_lock(&o2hb_live_lock);
     hb_task = reg->hr_task;
     if (o2hb_global_heartbeat_active())
         set_bit(reg->hr_region_num, o2hb_live_region_bitmap);
     spin_unlock(&o2hb_live_lock);
 
     if (hb_task)
         ret = count;
     else
         ret = -EIO;
 
     if (hb_task && o2hb_global_heartbeat_active())
         printk(KERN_NOTICE "o2hb: Heartbeat started on region %s (%pg)\n",
                config_item_name(&reg->hr_item), reg->hr_bdev);
 
 out3:
     if (ret < 0) {
         blkdev_put(reg->hr_bdev, FMODE_READ | FMODE_WRITE);
         reg->hr_bdev = NULL;
     }
 out2:
     fdput(f);
 out:
     return ret;
 }
 
 static ssize_t o2hb_region_pid_show(struct config_item *item, char *page)
 {
     struct o2hb_region *reg = to_o2hb_region(item);
     pid_t pid = 0;
 
     spin_lock(&o2hb_live_lock);
     if (reg->hr_task)
         pid = task_pid_nr(reg->hr_task);
     spin_unlock(&o2hb_live_lock);
 
     if (!pid)
         return 0;
 
     return sprintf(page, "%u\n", pid);
 }
 
 CONFIGFS_ATTR(o2hb_region_, block_bytes);
 CONFIGFS_ATTR(o2hb_region_, start_block);
 CONFIGFS_ATTR(o2hb_region_, blocks);
 CONFIGFS_ATTR(o2hb_region_, dev);
 CONFIGFS_ATTR_RO(o2hb_region_, pid);
 
 static struct configfs_attribute *o2hb_region_attrs[] = {
     &o2hb_region_attr_block_bytes,
     &o2hb_region_attr_start_block,
     &o2hb_region_attr_blocks,
     &o2hb_region_attr_dev,
     &o2hb_region_attr_pid,
     NULL,
 };
 
 static struct configfs_item_operations o2hb_region_item_ops = {
     .release        = o2hb_region_release,
 };
 
 static const struct config_item_type o2hb_region_type = {
     .ct_item_ops    = &o2hb_region_item_ops,
     .ct_attrs   = o2hb_region_attrs,
     .ct_owner   = THIS_MODULE,
 };
 
 /* heartbeat set */
 
 struct o2hb_heartbeat_group {
     struct config_group hs_group;
     /* some stuff? */
 };
 
 static struct o2hb_heartbeat_group *to_o2hb_heartbeat_group(struct config_group *group)
 {
     return group ?
         container_of(group, struct o2hb_heartbeat_group, hs_group)
         : NULL;
 }
 
 static void o2hb_debug_region_init(struct o2hb_region *reg,
                    struct dentry *parent)
 {
     struct dentry *dir;
 
     dir = debugfs_create_dir(config_item_name(&reg->hr_item), parent);
     reg->hr_debug_dir = dir;
 
     o2hb_debug_create(O2HB_DEBUG_LIVENODES, dir, &(reg->hr_db_livenodes),
               sizeof(*(reg->hr_db_livenodes)),
               O2HB_DB_TYPE_REGION_LIVENODES,
               sizeof(reg->hr_live_node_bitmap), O2NM_MAX_NODES,
               reg);
 
     o2hb_debug_create(O2HB_DEBUG_REGION_NUMBER, dir, &(reg->hr_db_regnum),
               sizeof(*(reg->hr_db_regnum)),
               O2HB_DB_TYPE_REGION_NUMBER, 0, O2NM_MAX_NODES, reg);
 
     o2hb_debug_create(O2HB_DEBUG_REGION_ELAPSED_TIME, dir,
               &(reg->hr_db_elapsed_time),
               sizeof(*(reg->hr_db_elapsed_time)),
               O2HB_DB_TYPE_REGION_ELAPSED_TIME, 0, 0, reg);
 
     o2hb_debug_create(O2HB_DEBUG_REGION_PINNED, dir, &(reg->hr_db_pinned),
               sizeof(*(reg->hr_db_pinned)),
               O2HB_DB_TYPE_REGION_PINNED, 0, 0, reg);
 
 }
 
 static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *group,
                               const char *name)
 {
     struct o2hb_region *reg = NULL;
     int ret;
 
     reg = kzalloc(sizeof(struct o2hb_region), GFP_KERNEL);
     if (reg == NULL)
         return ERR_PTR(-ENOMEM);
 
     if (strlen(name) > O2HB_MAX_REGION_NAME_LEN) {
         ret = -ENAMETOOLONG;
         goto free;
     }
 
     spin_lock(&o2hb_live_lock);
     reg->hr_region_num = 0;
     if (o2hb_global_heartbeat_active()) {
         reg->hr_region_num = find_first_zero_bit(o2hb_region_bitmap,
                              O2NM_MAX_REGIONS);
         if (reg->hr_region_num >= O2NM_MAX_REGIONS) {
             spin_unlock(&o2hb_live_lock);
             ret = -EFBIG;
             goto free;
         }
         set_bit(reg->hr_region_num, o2hb_region_bitmap);
     }
     list_add_tail(&reg->hr_all_item, &o2hb_all_regions);
     spin_unlock(&o2hb_live_lock);
 
     config_item_init_type_name(&reg->hr_item, name, &o2hb_region_type);
 
     /* this is the same way to generate msg key as dlm, for local heartbeat,
      * name is also the same, so make initial crc value different to avoid
      * message key conflict.
      */
     reg->hr_key = crc32_le(reg->hr_region_num + O2NM_MAX_REGIONS,
         name, strlen(name));
     INIT_LIST_HEAD(&reg->hr_handler_list);
     ret = o2net_register_handler(O2HB_NEGO_TIMEOUT_MSG, reg->hr_key,
             sizeof(struct o2hb_nego_msg),
             o2hb_nego_timeout_handler,
             reg, NULL, &reg->hr_handler_list);
     if (ret)
         goto remove_item;
 
     ret = o2net_register_handler(O2HB_NEGO_APPROVE_MSG, reg->hr_key,
             sizeof(struct o2hb_nego_msg),
             o2hb_nego_approve_handler,
             reg, NULL, &reg->hr_handler_list);
     if (ret)
         goto unregister_handler;
 
     o2hb_debug_region_init(reg, o2hb_debug_dir);
 
     return &reg->hr_item;
 
 unregister_handler:
     o2net_unregister_handler_list(&reg->hr_handler_list);
 remove_item:
     spin_lock(&o2hb_live_lock);
     list_del(&reg->hr_all_item);
     if (o2hb_global_heartbeat_active())
         clear_bit(reg->hr_region_num, o2hb_region_bitmap);
     spin_unlock(&o2hb_live_lock);
 free:
     kfree(reg);
     return ERR_PTR(ret);
 }
 
 static void o2hb_heartbeat_group_drop_item(struct config_group *group,
                        struct config_item *item)
 {
     struct task_struct *hb_task;
     struct o2hb_region *reg = to_o2hb_region(item);
     int quorum_region = 0;
 
     /* stop the thread when the user removes the region dir */
     spin_lock(&o2hb_live_lock);
     hb_task = reg->hr_task;
     reg->hr_task = NULL;
     reg->hr_item_dropped = 1;
     spin_unlock(&o2hb_live_lock);
 
     if (hb_task)
         kthread_stop(hb_task);
 
     if (o2hb_global_heartbeat_active()) {
         spin_lock(&o2hb_live_lock);
         clear_bit(reg->hr_region_num, o2hb_region_bitmap);
         clear_bit(reg->hr_region_num, o2hb_live_region_bitmap);
         if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
             quorum_region = 1;
         clear_bit(reg->hr_region_num, o2hb_quorum_region_bitmap);
         spin_unlock(&o2hb_live_lock);
         printk(KERN_NOTICE "o2hb: Heartbeat %s on region %s (%pg)\n",
                ((atomic_read(&reg->hr_steady_iterations) == 0) ?
             "stopped" : "start aborted"), config_item_name(item),
                reg->hr_bdev);
     }
 
     /*
      * If we're racing a dev_write(), we need to wake them.  They will
      * check reg->hr_task
      */
     if (atomic_read(&reg->hr_steady_iterations) != 0) {
         reg->hr_aborted_start = 1;
         atomic_set(&reg->hr_steady_iterations, 0);
         wake_up(&o2hb_steady_queue);
     }
 
     config_item_put(item);
 
     if (!o2hb_global_heartbeat_active() || !quorum_region)
         return;
 
     /*
      * If global heartbeat active and there are dependent users,
      * pin all regions if quorum region count <= CUT_OFF
      */
     spin_lock(&o2hb_live_lock);
 
     if (!o2hb_dependent_users)
         goto unlock;
 
     if (bitmap_weight(o2hb_quorum_region_bitmap,
                O2NM_MAX_REGIONS) <= O2HB_PIN_CUT_OFF)
         o2hb_region_pin(NULL);
 
 unlock:
     spin_unlock(&o2hb_live_lock);
 }
 
 static ssize_t o2hb_heartbeat_group_dead_threshold_show(struct config_item *item,
         char *page)
 {
     return sprintf(page, "%u\n", o2hb_dead_threshold);
 }
 
 static ssize_t o2hb_heartbeat_group_dead_threshold_store(struct config_item *item,
         const char *page, size_t count)
 {
     unsigned long tmp;
     char *p = (char *)page;
 
     tmp = simple_strtoul(p, &p, 10);
     if (!p || (*p && (*p != '\n')))
                 return -EINVAL;
 
     /* this will validate ranges for us. */
     o2hb_dead_threshold_set((unsigned int) tmp);
 
     return count;
 }
 
 static ssize_t o2hb_heartbeat_group_mode_show(struct config_item *item,
         char *page)
 {
     return sprintf(page, "%s\n",
                o2hb_heartbeat_mode_desc[o2hb_heartbeat_mode]);
 }
 
 static ssize_t o2hb_heartbeat_group_mode_store(struct config_item *item,
         const char *page, size_t count)
 {
     unsigned int i;
     int ret;
     size_t len;
 
     len = (page[count - 1] == '\n') ? count - 1 : count;
     if (!len)
         return -EINVAL;
 
     for (i = 0; i < O2HB_HEARTBEAT_NUM_MODES; ++i) {
         if (strncasecmp(page, o2hb_heartbeat_mode_desc[i], len))
             continue;
 
         ret = o2hb_global_heartbeat_mode_set(i);
         if (!ret)
             printk(KERN_NOTICE "o2hb: Heartbeat mode set to %s\n",
                    o2hb_heartbeat_mode_desc[i]);
         return count;
     }
 
     return -EINVAL;
 
 }
 
 CONFIGFS_ATTR(o2hb_heartbeat_group_, dead_threshold);
 CONFIGFS_ATTR(o2hb_heartbeat_group_, mode);
 
 static struct configfs_attribute *o2hb_heartbeat_group_attrs[] = {
     &o2hb_heartbeat_group_attr_dead_threshold,
     &o2hb_heartbeat_group_attr_mode,
     NULL,
 };
 
 static struct configfs_group_operations o2hb_heartbeat_group_group_ops = {
     .make_item  = o2hb_heartbeat_group_make_item,
     .drop_item  = o2hb_heartbeat_group_drop_item,
 };
 
 static const struct config_item_type o2hb_heartbeat_group_type = {
     .ct_group_ops   = &o2hb_heartbeat_group_group_ops,
     .ct_attrs   = o2hb_heartbeat_group_attrs,
     .ct_owner   = THIS_MODULE,
 };
 
 /* this is just here to avoid touching group in heartbeat.h which the
  * entire damn world #includes */
 struct config_group *o2hb_alloc_hb_set(void)
 {
     struct o2hb_heartbeat_group *hs = NULL;
     struct config_group *ret = NULL;
 
     hs = kzalloc(sizeof(struct o2hb_heartbeat_group), GFP_KERNEL);
     if (hs == NULL)
         goto out;
 
     config_group_init_type_name(&hs->hs_group, "heartbeat",
                     &o2hb_heartbeat_group_type);
 
     ret = &hs->hs_group;
 out:
     if (ret == NULL)
         kfree(hs);
     return ret;
 }
 
 void o2hb_free_hb_set(struct config_group *group)
 {
     struct o2hb_heartbeat_group *hs = to_o2hb_heartbeat_group(group);
     kfree(hs);
 }
 
 /* hb callback registration and issuing */
 
 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type)
 {
     if (type == O2HB_NUM_CB)
         return ERR_PTR(-EINVAL);
 
     return &o2hb_callbacks[type];
 }
 
 void o2hb_setup_callback(struct o2hb_callback_func *hc,
              enum o2hb_callback_type type,
              o2hb_cb_func *func,
              void *data,
              int priority)
 {
     INIT_LIST_HEAD(&hc->hc_item);
     hc->hc_func = func;
     hc->hc_data = data;
     hc->hc_priority = priority;
     hc->hc_type = type;
     hc->hc_magic = O2HB_CB_MAGIC;
 }
 EXPORT_SYMBOL_GPL(o2hb_setup_callback);
 
 /*
  * In local heartbeat mode, region_uuid passed matches the dlm domain name.
  * In global heartbeat mode, region_uuid passed is NULL.
  *
  * In local, we only pin the matching region. In global we pin all the active
  * regions.
  */
 static int o2hb_region_pin(const char *region_uuid)
 {
     int ret = 0, found = 0;
     struct o2hb_region *reg;
     char *uuid;
 
     assert_spin_locked(&o2hb_live_lock);
 
     list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
         if (reg->hr_item_dropped)
             continue;
 
         uuid = config_item_name(&reg->hr_item);
 
         /* local heartbeat */
         if (region_uuid) {
             if (strcmp(region_uuid, uuid))
                 continue;
             found = 1;
         }
 
         if (reg->hr_item_pinned || reg->hr_item_dropped)
             goto skip_pin;
 
         /* Ignore ENOENT only for local hb (userdlm domain) */
         ret = o2nm_depend_item(&reg->hr_item);
         if (!ret) {
             mlog(ML_CLUSTER, "Pin region %s\n", uuid);
             reg->hr_item_pinned = 1;
         } else {
             if (ret == -ENOENT && found)
                 ret = 0;
             else {
                 mlog(ML_ERROR, "Pin region %s fails with %d\n",
                      uuid, ret);
                 break;
             }
         }
 skip_pin:
         if (found)
             break;
     }
 
     return ret;
 }
 
 /*
  * In local heartbeat mode, region_uuid passed matches the dlm domain name.
  * In global heartbeat mode, region_uuid passed is NULL.
  *
  * In local, we only unpin the matching region. In global we unpin all the
  * active regions.
  */
 static void o2hb_region_unpin(const char *region_uuid)
 {
     struct o2hb_region *reg;
     char *uuid;
     int found = 0;
 
     assert_spin_locked(&o2hb_live_lock);
 
     list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
         if (reg->hr_item_dropped)
             continue;
 
         uuid = config_item_name(&reg->hr_item);
         if (region_uuid) {
             if (strcmp(region_uuid, uuid))
                 continue;
             found = 1;
         }
 
         if (reg->hr_item_pinned) {
             mlog(ML_CLUSTER, "Unpin region %s\n", uuid);
             o2nm_undepend_item(&reg->hr_item);
             reg->hr_item_pinned = 0;
         }
         if (found)
             break;
     }
 }
 
 static int o2hb_region_inc_user(const char *region_uuid)
 {
     int ret = 0;
 
     spin_lock(&o2hb_live_lock);
 
     /* local heartbeat */
     if (!o2hb_global_heartbeat_active()) {
         ret = o2hb_region_pin(region_uuid);
         goto unlock;
     }
 
     /*
      * if global heartbeat active and this is the first dependent user,
      * pin all regions if quorum region count <= CUT_OFF
      */
     o2hb_dependent_users++;
     if (o2hb_dependent_users > 1)
         goto unlock;
 
     if (bitmap_weight(o2hb_quorum_region_bitmap,
                O2NM_MAX_REGIONS) <= O2HB_PIN_CUT_OFF)
         ret = o2hb_region_pin(NULL);
 
 unlock:
     spin_unlock(&o2hb_live_lock);
     return ret;
 }
 
 static void o2hb_region_dec_user(const char *region_uuid)
 {
     spin_lock(&o2hb_live_lock);
 
     /* local heartbeat */
     if (!o2hb_global_heartbeat_active()) {
         o2hb_region_unpin(region_uuid);
         goto unlock;
     }
 
     /*
      * if global heartbeat active and there are no dependent users,
      * unpin all quorum regions
      */
     o2hb_dependent_users--;
     if (!o2hb_dependent_users)
         o2hb_region_unpin(NULL);
 
 unlock:
     spin_unlock(&o2hb_live_lock);
 }
 
 int o2hb_register_callback(const char *region_uuid,
                struct o2hb_callback_func *hc)
 {
     struct o2hb_callback_func *f;
     struct o2hb_callback *hbcall;
     int ret;
 
     BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
     BUG_ON(!list_empty(&hc->hc_item));
 
     hbcall = hbcall_from_type(hc->hc_type);
     if (IS_ERR(hbcall)) {
         ret = PTR_ERR(hbcall);
         goto out;
     }
 
     if (region_uuid) {
         ret = o2hb_region_inc_user(region_uuid);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     down_write(&o2hb_callback_sem);
 
     list_for_each_entry(f, &hbcall->list, hc_item) {
         if (hc->hc_priority < f->hc_priority) {
             list_add_tail(&hc->hc_item, &f->hc_item);
             break;
         }
     }
     if (list_empty(&hc->hc_item))
         list_add_tail(&hc->hc_item, &hbcall->list);
 
     up_write(&o2hb_callback_sem);
     ret = 0;
 out:
     mlog(ML_CLUSTER, "returning %d on behalf of %p for funcs %p\n",
          ret, __builtin_return_address(0), hc);
     return ret;
 }
 EXPORT_SYMBOL_GPL(o2hb_register_callback);
 
 void o2hb_unregister_callback(const char *region_uuid,
                   struct o2hb_callback_func *hc)
 {
     BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
 
     mlog(ML_CLUSTER, "on behalf of %p for funcs %p\n",
          __builtin_return_address(0), hc);
 
     /* XXX Can this happen _with_ a region reference? */
     if (list_empty(&hc->hc_item))
         return;
 
     if (region_uuid)
         o2hb_region_dec_user(region_uuid);
 
     down_write(&o2hb_callback_sem);
 
     list_del_init(&hc->hc_item);
 
     up_write(&o2hb_callback_sem);
 }
 EXPORT_SYMBOL_GPL(o2hb_unregister_callback);
 
 int o2hb_check_node_heartbeating_no_sem(u8 node_num)
 {
     unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
 
     spin_lock(&o2hb_live_lock);
     o2hb_fill_node_map_from_callback(testing_map, sizeof(testing_map));
     spin_unlock(&o2hb_live_lock);
     if (!test_bit(node_num, testing_map)) {
         mlog(ML_HEARTBEAT,
              "node (%u) does not have heartbeating enabled.\n",
              node_num);
         return 0;
     }
 
     return 1;
 }
 EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating_no_sem);
 
 int o2hb_check_node_heartbeating_from_callback(u8 node_num)
 {
     unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
 
     o2hb_fill_node_map_from_callback(testing_map, sizeof(testing_map));
     if (!test_bit(node_num, testing_map)) {
         mlog(ML_HEARTBEAT,
              "node (%u) does not have heartbeating enabled.\n",
              node_num);
         return 0;
     }
 
     return 1;
 }
 EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating_from_callback);
 
 /*
  * this is just a hack until we get the plumbing which flips file systems
  * read only and drops the hb ref instead of killing the node dead.
  */
 void o2hb_stop_all_regions(void)
 {
     struct o2hb_region *reg;
 
     mlog(ML_ERROR, "stopping heartbeat on all active regions.\n");
 
     spin_lock(&o2hb_live_lock);
 
     list_for_each_entry(reg, &o2hb_all_regions, hr_all_item)
         reg->hr_unclean_stop = 1;
 
     spin_unlock(&o2hb_live_lock);
 }
 EXPORT_SYMBOL_GPL(o2hb_stop_all_regions);
 
 int o2hb_get_all_regions(char *region_uuids, u8 max_regions)
 {
     struct o2hb_region *reg;
     int numregs = 0;
     char *p;
 
     spin_lock(&o2hb_live_lock);
 
     p = region_uuids;
     list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
         if (reg->hr_item_dropped)
             continue;
 
         mlog(0, "Region: %s\n", config_item_name(&reg->hr_item));
         if (numregs < max_regions) {
             memcpy(p, config_item_name(&reg->hr_item),
                    O2HB_MAX_REGION_NAME_LEN);
             p += O2HB_MAX_REGION_NAME_LEN;
         }
         numregs++;
     }
 
     spin_unlock(&o2hb_live_lock);
 
     return numregs;
 }
 EXPORT_SYMBOL_GPL(o2hb_get_all_regions);
 
 int o2hb_global_heartbeat_active(void)
 {
     return (o2hb_heartbeat_mode == O2HB_HEARTBEAT_GLOBAL);
 }
 EXPORT_SYMBOL(o2hb_global_heartbeat_active);

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