2 files changed, 21 insertions, 14 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 00c3fde39a12..03dcbfbe250f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -580,13 +580,17 @@ static void mddev_unlock(mddev_t * mddev)
                  * 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.
+                 * So hold set sysfs_active while the remove in happeing,
+                 * and anything else which might set ->to_remove or my
+                 * otherwise change the sysfs namespace will fail with
+                 * -EBUSY if sysfs_active is still set.
+                 * We set sysfs_active under reconfig_mutex and elsewhere
+                 * test it under the same mutex to ensure its correct value
+                 * is seen.
                  */
                 struct attribute_group *to_remove = mddev->to_remove;
                 mddev->to_remove = NULL;
-                mutex_lock(&mddev->open_mutex);
+                mddev->sysfs_active = 1;
                 mutex_unlock(&mddev->reconfig_mutex);
 
                 if (mddev->kobj.sd) {
@@ -600,7 +604,7 @@ static void mddev_unlock(mddev_t * mddev)
                                 mddev->sysfs_action = NULL;
                         }
                 }
-                mutex_unlock(&mddev->open_mutex);
+                mddev->sysfs_active = 0;
         } else
                 mutex_unlock(&mddev->reconfig_mutex);
 
@@ -3008,7 +3012,9 @@ level_store(mddev_t *mddev, const char *buf, size_t len)
          *  - new personality will access other array.
          */
 
-        if (mddev->sync_thread || mddev->reshape_position != MaxSector)
+        if (mddev->sync_thread ||
+            mddev->reshape_position != MaxSector ||
+            mddev->sysfs_active)
                 return -EBUSY;
 
         if (!mddev->pers->quiesce) {
@@ -4393,13 +4399,9 @@ int 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);
+        /* Cannot run until previous stop completes properly */
+        if (mddev->sysfs_active)
+                return -EBUSY;
 
         /*
          * Analyze all RAID superblock(s)
@@ -4770,7 +4772,8 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
         mdk_rdev_t *rdev;
 
         mutex_lock(&mddev->open_mutex);
-        if (atomic_read(&mddev->openers) > is_open) {
+        if (atomic_read(&mddev->openers) > is_open ||
+            mddev->sysfs_active) {
                 printk("md: %s still in use.\n",mdname(mddev));
                 err = -EBUSY;
         } else if (mddev->pers) {
diff --git a/drivers/md/md.h b/drivers/md/md.h
index cccbadb31bae..6f797eceae31 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -145,6 +145,10 @@ struct mddev_s
         int                             suspended;
         atomic_t                        active_io;
         int                             ro;
+        int                             sysfs_active; /* set when sysfs deletes
+                                                       * are happening, so run/
+                                                       * takeover/stop are not safe
+                                                       */
 
         struct gendisk                  *gendisk;