1 files changed, 94 insertions, 30 deletions

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 34f14a14fb4e..b3832c67194a 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2007 Red Hat, Inc.  All rights reserved.
+ * Copyright (C) 2006-2008 Red Hat, Inc.  All rights reserved.
  *
  * This copyrighted material is made available to anyone wishing to use,
  * modify, copy, or redistribute it subject to the terms and conditions
@@ -15,7 +15,6 @@
 #include <linux/poll.h>
 #include <linux/signal.h>
 #include <linux/spinlock.h>
-#include <linux/smp_lock.h>
 #include <linux/dlm.h>
 #include <linux/dlm_device.h>
 
@@ -27,6 +26,8 @@
 
 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
 
@@ -340,10 +341,15 @@ static int device_user_deadlock(struct dlm_user_proc *proc,
         return error;
 }
 
-static int create_misc_device(struct dlm_ls *ls, char *name)
+static int dlm_device_register(struct dlm_ls *ls, char *name)
 {
         int error, len;
 
+        /* The device is already registered.  This happens when the
+           lockspace is created multiple times from userspace. */
+        if (ls->ls_device.name)
+                return 0;
+
         error = -ENOMEM;
         len = strlen(name) + strlen(name_prefix) + 2;
         ls->ls_device.name = kzalloc(len, GFP_KERNEL);
@@ -363,6 +369,22 @@ fail:
         return error;
 }
 
+int dlm_device_deregister(struct dlm_ls *ls)
+{
+        int error;
+
+        /* The device is not registered.  This happens when the lockspace
+           was never used from userspace, or when device_create_lockspace()
+           calls dlm_release_lockspace() after the register fails. */
+        if (!ls->ls_device.name)
+                return 0;
+
+        error = misc_deregister(&ls->ls_device);
+        if (!error)
+                kfree(ls->ls_device.name);
+        return error;
+}
+
 static int device_user_purge(struct dlm_user_proc *proc,
                              struct dlm_purge_params *params)
 {
@@ -397,7 +419,7 @@ static int device_create_lockspace(struct dlm_lspace_params *params)
         if (!ls)
                 return -ENOENT;
 
-        error = create_misc_device(ls, params->name);
+        error = dlm_device_register(ls, params->name);
         dlm_put_lockspace(ls);
 
         if (error)
@@ -421,31 +443,22 @@ static int device_remove_lockspace(struct dlm_lspace_params *params)
         if (!ls)
                 return -ENOENT;
 
-        /* Deregister the misc device first, so we don't have
-         * a device that's not attached to a lockspace. If
-         * dlm_release_lockspace fails then we can recreate it
-         */
-        error = misc_deregister(&ls->ls_device);
-        if (error) {
-                dlm_put_lockspace(ls);
-                goto out;
-        }
-        kfree(ls->ls_device.name);
-
         if (params->flags & DLM_USER_LSFLG_FORCEFREE)
                 force = 2;
 
         lockspace = ls->ls_local_handle;
+        dlm_put_lockspace(ls);
 
-        /* dlm_release_lockspace waits for references to go to zero,
-           so all processes will need to close their device for the ls
-           before the release will procede */
+        /* The final dlm_release_lockspace waits for references to go to
+           zero, so all processes will need to close their device for the
+           ls before the release will proceed.  release also calls the
+           device_deregister above.  Converting a positive return value
+           from release to zero means that userspace won't know when its
+           release was the final one, but it shouldn't need to know. */
 
-        dlm_put_lockspace(ls);
         error = dlm_release_lockspace(lockspace, force);
-        if (error)
-                create_misc_device(ls, ls->ls_name);
- out:
+        if (error > 0)
+                error = 0;
         return error;
 }
 
@@ -623,17 +636,13 @@ static int device_open(struct inode *inode, struct file *file)
         struct dlm_user_proc *proc;
         struct dlm_ls *ls;
 
-        lock_kernel();
         ls = dlm_find_lockspace_device(iminor(inode));
-        if (!ls) {
-                unlock_kernel();
+        if (!ls)
                 return -ENOENT;
-        }
 
         proc = kzalloc(sizeof(struct dlm_user_proc), GFP_KERNEL);
         if (!proc) {
                 dlm_put_lockspace(ls);
-                unlock_kernel();
                 return -ENOMEM;
         }
 
@@ -645,7 +654,6 @@ static int device_open(struct inode *inode, struct file *file)
         spin_lock_init(&proc->locks_spin);
         init_waitqueue_head(&proc->wait);
         file->private_data = proc;
-        unlock_kernel();
 
         return 0;
 }
@@ -878,9 +886,28 @@ 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();
         file->private_data = NULL;
         return 0;
 }
@@ -890,6 +917,20 @@ 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,
@@ -913,19 +954,42 @@ 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);
 }