md: factor do_md_run to separate accesses to ->gendisk

As part of relaxing the binding between an mddev and gendisk,
we separate do_md_run into two functions.
  md_run does all the work internal to md
  do_md_run calls md_run and makes and changes to gendisk
     that are required.
Signed-off-by: NNeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -4297,11 +4297,10 @@ static void md_safemode_timeout(unsigned long data)
 
 static int start_dirty_degraded;
 
-static int do_md_run(mddev_t * mddev)
+static int md_run(mddev_t *mddev)
 {
 	int err;
 	mdk_rdev_t *rdev;
-	struct gendisk *disk;
 	struct mdk_personality *pers;
 
 	if (list_empty(&mddev->disks))
@@ -4366,8 +4365,6 @@ static int do_md_run(mddev_t * mddev)
 		sysfs_notify_dirent(rdev->sysfs_state);
 	}
 
-	disk = mddev->gendisk;
-
 	spin_lock(&pers_lock);
 	pers = find_pers(mddev->level, mddev->clevel);
 	if (!pers || !try_module_get(pers->owner)) {
@@ -4495,21 +4492,32 @@ static int do_md_run(mddev_t * mddev)
 	if (mddev->flags)
 		md_update_sb(mddev, 0);
 
-	set_capacity(disk, mddev->array_sectors);
-
 	md_wakeup_thread(mddev->thread);
 	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
 
-	revalidate_disk(mddev->gendisk);
 	md_new_event(mddev);
 	sysfs_notify_dirent(mddev->sysfs_state);
 	if (mddev->sysfs_action)
 		sysfs_notify_dirent(mddev->sysfs_action);
 	sysfs_notify(&mddev->kobj, NULL, "degraded");
-	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
 	return 0;
 }
 
+static int do_md_run(mddev_t *mddev)
+{
+	int err;
+
+	err = md_run(mddev);
+	if (err)
+		goto out;
+
+	set_capacity(mddev->gendisk, mddev->array_sectors);
+	revalidate_disk(mddev->gendisk);
+	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
+out:
+	return err;
+}
+
 static int restart_array(mddev_t *mddev)
 {
 	struct gendisk *disk = mddev->gendisk;