1 files changed, 60 insertions, 1 deletions

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 6542110c0da4..81627b502a56 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -27,6 +27,8 @@
 
 static const char name_prefix[] = "dlm";
 static const struct file_operations device_fops;
+static atomic_t dlm_monitor_opened;
+static int dlm_monitor_unused = 1;
 
 #ifdef CONFIG_COMPAT
 
@@ -890,6 +892,26 @@ static unsigned int device_poll(struct file *file, poll_table *wait)
         return 0;
 }
 
+int dlm_user_daemon_available(void)
+{
+        /* dlm_controld hasn't started (or, has started, but not
+           properly populated configfs) */
+
+        if (!dlm_our_nodeid())
+                return 0;
+
+        /* This is to deal with versions of dlm_controld that don't
+           know about the monitor device.  We assume that if the
+           dlm_controld was started (above), but the monitor device
+           was never opened, that it's an old version.  dlm_controld
+           should open the monitor device before populating configfs. */
+
+        if (dlm_monitor_unused)
+                return 1;
+
+        return atomic_read(&dlm_monitor_opened) ? 1 : 0;
+}
+
 static int ctl_device_open(struct inode *inode, struct file *file)
 {
         cycle_kernel_lock();
@@ -902,6 +924,20 @@ static int ctl_device_close(struct inode *inode, struct file *file)
         return 0;
 }
 
+static int monitor_device_open(struct inode *inode, struct file *file)
+{
+        atomic_inc(&dlm_monitor_opened);
+        dlm_monitor_unused = 0;
+        return 0;
+}
+
+static int monitor_device_close(struct inode *inode, struct file *file)
+{
+        if (atomic_dec_and_test(&dlm_monitor_opened))
+                dlm_stop_lockspaces();
+        return 0;
+}
+
 static const struct file_operations device_fops = {
         .open    = device_open,
         .release = device_close,
@@ -925,19 +961,42 @@ static struct miscdevice ctl_device = {
         .minor = MISC_DYNAMIC_MINOR,
 };
 
+static const struct file_operations monitor_device_fops = {
+        .open    = monitor_device_open,
+        .release = monitor_device_close,
+        .owner   = THIS_MODULE,
+};
+
+static struct miscdevice monitor_device = {
+        .name  = "dlm-monitor",
+        .fops  = &monitor_device_fops,
+        .minor = MISC_DYNAMIC_MINOR,
+};
+
 int __init dlm_user_init(void)
 {
         int error;
 
+        atomic_set(&dlm_monitor_opened, 0);
+
         error = misc_register(&ctl_device);
-        if (error)
+        if (error) {
                 log_print("misc_register failed for control device");
+                goto out;
+        }
 
+        error = misc_register(&monitor_device);
+        if (error) {
+                log_print("misc_register failed for monitor device");
+                misc_deregister(&ctl_device);
+        }
+ out:
         return error;
 }
 
 void dlm_user_exit(void)
 {
         misc_deregister(&ctl_device);
+        misc_deregister(&monitor_device);
 }