1 files changed, 17 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) {