1 files changed, 93 insertions, 3 deletions

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 979113479c66..2bd7f788cf34 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -1335,6 +1335,7 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
         ret = wait_event_interruptible(o2hb_steady_queue,
                                 atomic_read(&reg->hr_steady_iterations) == 0);
         if (ret) {
+                /* We got interrupted (hello ptrace!).  Clean up */
                 spin_lock(&o2hb_live_lock);
                 hb_task = reg->hr_task;
                 reg->hr_task = NULL;
@@ -1345,7 +1346,16 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
                 goto out;
         }
 
-        ret = count;
+        /* Ok, we were woken.  Make sure it wasn't by drop_item() */
+        spin_lock(&o2hb_live_lock);
+        hb_task = reg->hr_task;
+        spin_unlock(&o2hb_live_lock);
+
+        if (hb_task)
+                ret = count;
+        else
+                ret = -EIO;
+
 out:
         if (filp)
                 fput(filp);
@@ -1523,6 +1533,15 @@ static void o2hb_heartbeat_group_drop_item(struct config_group *group,
         if (hb_task)
                 kthread_stop(hb_task);
 
+        /*
+         * 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) {
+                atomic_set(&reg->hr_steady_iterations, 0);
+                wake_up(&o2hb_steady_queue);
+        }
+
         config_item_put(item);
 }
 
@@ -1665,7 +1684,67 @@ void o2hb_setup_callback(struct o2hb_callback_func *hc,
 }
 EXPORT_SYMBOL_GPL(o2hb_setup_callback);
 
-int o2hb_register_callback(struct o2hb_callback_func *hc)
+static struct o2hb_region *o2hb_find_region(const char *region_uuid)
+{
+        struct o2hb_region *p, *reg = NULL;
+
+        assert_spin_locked(&o2hb_live_lock);
+
+        list_for_each_entry(p, &o2hb_all_regions, hr_all_item) {
+                if (!strcmp(region_uuid, config_item_name(&p->hr_item))) {
+                        reg = p;
+                        break;
+                }
+        }
+
+        return reg;
+}
+
+static int o2hb_region_get(const char *region_uuid)
+{
+        int ret = 0;
+        struct o2hb_region *reg;
+
+        spin_lock(&o2hb_live_lock);
+
+        reg = o2hb_find_region(region_uuid);
+        if (!reg)
+                ret = -ENOENT;
+        spin_unlock(&o2hb_live_lock);
+
+        if (ret)
+                goto out;
+
+        ret = o2nm_depend_this_node();
+        if (ret)
+                goto out;
+
+        ret = o2nm_depend_item(&reg->hr_item);
+        if (ret)
+                o2nm_undepend_this_node();
+
+out:
+        return ret;
+}
+
+static void o2hb_region_put(const char *region_uuid)
+{
+        struct o2hb_region *reg;
+
+        spin_lock(&o2hb_live_lock);
+
+        reg = o2hb_find_region(region_uuid);
+
+        spin_unlock(&o2hb_live_lock);
+
+        if (reg) {
+                o2nm_undepend_item(&reg->hr_item);
+                o2nm_undepend_this_node();
+        }
+}
+
+int o2hb_register_callback(const char *region_uuid,
+                           struct o2hb_callback_func *hc)
 {
         struct o2hb_callback_func *tmp;
         struct list_head *iter;
@@ -1681,6 +1760,12 @@ int o2hb_register_callback(struct o2hb_callback_func *hc)
                 goto out;
         }
 
+        if (region_uuid) {
+                ret = o2hb_region_get(region_uuid);
+                if (ret)
+                        goto out;
+        }
+
         down_write(&o2hb_callback_sem);
 
         list_for_each(iter, &hbcall->list) {
@@ -1702,16 +1787,21 @@ out:
 }
 EXPORT_SYMBOL_GPL(o2hb_register_callback);
 
-void o2hb_unregister_callback(struct o2hb_callback_func *hc)
+void o2hb_unregister_callback(const char *region_uuid,
+                              struct o2hb_callback_func *hc)
 {
         BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
 
         mlog(ML_HEARTBEAT, "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_put(region_uuid);
+
         down_write(&o2hb_callback_sem);
 
         list_del_init(&hc->hc_item);