md: get sysfs entry after redundancy attr group create

"sync_completed" and "degraded" belongs to redundancy attr group,
it was not exist yet when md device was created.

Reported-by: kernel test robot <rong.a.chen@intel.com>
Fixes: e1a86db ("md: fix deadlock causing by sysfs_notify")
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Song Liu <songliubraving@fb.com>

drivers/md/md.c

@@ -876,7 +876,13 @@ void mddev_unlock(struct mddev *mddev)
 				sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
 				if (mddev->sysfs_action)
 					sysfs_put(mddev->sysfs_action);
+				if (mddev->sysfs_completed)
+					sysfs_put(mddev->sysfs_completed);
+				if (mddev->sysfs_degraded)
+					sysfs_put(mddev->sysfs_degraded);
 				mddev->sysfs_action = NULL;
+				mddev->sysfs_completed = NULL;
+				mddev->sysfs_degraded = NULL;
 			}
 		}
 		mddev->sysfs_active = 0;
@@ -4094,6 +4100,8 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
 			pr_warn("md: cannot register extra attributes for %s\n",
 				mdname(mddev));
 		mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, "sync_action");
+		mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
+		mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
 	}
 	if (oldpers->sync_request != NULL &&
 	    pers->sync_request == NULL) {
@@ -5609,14 +5617,9 @@ static void md_free(struct kobject *ko)
 
 	if (mddev->sysfs_state)
 		sysfs_put(mddev->sysfs_state);
-	if (mddev->sysfs_completed)
-		sysfs_put(mddev->sysfs_completed);
-	if (mddev->sysfs_degraded)
-		sysfs_put(mddev->sysfs_degraded);
 	if (mddev->sysfs_level)
 		sysfs_put(mddev->sysfs_level);
 
-
 	if (mddev->gendisk)
 		del_gendisk(mddev->gendisk);
 	if (mddev->queue)
@@ -5783,8 +5786,6 @@ static int md_alloc(dev_t dev, char *name)
 	if (!error && mddev->kobj.sd) {
 		kobject_uevent(&mddev->kobj, KOBJ_ADD);
 		mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
-		mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
-		mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
 		mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
 	}
 	mddev_put(mddev);
@@ -6064,6 +6065,8 @@ int md_run(struct mddev *mddev)
 			pr_warn("md: cannot register extra attributes for %s\n",
 				mdname(mddev));
 		mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
+		mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
+		mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
 	} else if (mddev->ro == 2) /* auto-readonly not meaningful */
 		mddev->ro = 0;