ocfs2: Wake up a starting region if it gets killed in the background.

Tell o2cb_region_dev_write() to wake up if rmdir(2) happens on the
heartbeat region while it is starting up.  Then o2hb_region_dev_write()
can check to see if it is alive and act accordingly.  This prevents a hang
(not being woken) and a crash (if it's woken by a signal).

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 2877d468f115..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);
 }