md: remove unneeded sysfs files more promptly

[safe/jmp/linux-2.6] / drivers / md / md.c

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 08f6651..edf777f 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -507,9 +507,32 @@ static inline int mddev_trylock(mddev_t * mddev)
        return mutex_trylock(&mddev->reconfig_mutex);
 }
 
+static struct attribute_group md_redundancy_group;
+
 static inline void mddev_unlock(mddev_t * mddev)
 {
-       mutex_unlock(&mddev->reconfig_mutex);
+       if (mddev->pers == NULL && mddev->private) {
+               /* These cannot be removed under reconfig_mutex as
+                * an access to the files will try to take reconfig_mutex
+                * while holding the file unremovable, which leads to
+                * a deadlock.
+                * So hold open_mutex instead - we are allowed to take
+                * it while holding reconfig_mutex, and md_run can
+                * use it to wait for the remove to complete.
+                */
+               mutex_lock(&mddev->open_mutex);
+               mutex_unlock(&mddev->reconfig_mutex);
+
+               sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
+               if (mddev->private != (void*)1)
+                       sysfs_remove_group(&mddev->kobj, mddev->private);
+               if (mddev->sysfs_action)
+                       sysfs_put(mddev->sysfs_action);
+               mddev->sysfs_action = NULL;
+               mddev->private = NULL;
+               mutex_unlock(&mddev->open_mutex);
+       } else
+               mutex_unlock(&mddev->reconfig_mutex);
 
        md_wakeup_thread(mddev->thread);
 }
@@ -4075,15 +4098,6 @@ static void mddev_delayed_delete(struct work_struct *ws)
 {
        mddev_t *mddev = container_of(ws, mddev_t, del_work);
 
-       if (mddev->private) {
-               sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
-               if (mddev->private != (void*)1)
-                       sysfs_remove_group(&mddev->kobj, mddev->private);
-               if (mddev->sysfs_action)
-                       sysfs_put(mddev->sysfs_action);
-               mddev->sysfs_action = NULL;
-               mddev->private = NULL;
-       }
        sysfs_remove_group(&mddev->kobj, &md_bitmap_group);
        kobject_del(&mddev->kobj);
        kobject_put(&mddev->kobj);
@@ -4241,6 +4255,13 @@ static int do_md_run(mddev_t * mddev)
        if (mddev->pers)
                return -EBUSY;
 
+       /* These two calls synchronise us with the
+        * sysfs_remove_group calls in mddev_unlock,
+        * so they must have completed.
+        */
+       mutex_lock(&mddev->open_mutex);
+       mutex_unlock(&mddev->open_mutex);
+
        /*
         * Analyze all RAID superblock(s)
         */