md: reinitialise more mddev fields in do_md_stop.

I keep finding problems where an mddev gets reused and some fields has a value
from a previous usage that confuses the new usage.  So clear all fields that
could possible need clearing when calling do_md_stop.

Also initialise the 'level' of a new array to LEVEL_NONE (which isn't 0).

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/md/md.c

@@ -276,6 +276,7 @@ static mddev_t * mddev_find(dev_t unit)
 	init_waitqueue_head(&new->sb_wait);
 	new->reshape_position = MaxSector;
 	new->resync_max = MaxSector;
+	new->level = LEVEL_NONE;
 
 	new->queue = blk_alloc_queue(GFP_KERNEL);
 	if (!new->queue) {
@@ -3714,6 +3715,30 @@ static int do_md_stop(mddev_t * mddev, int mode)
 		mddev->reshape_position = MaxSector;
 		mddev->external = 0;
 		mddev->persistent = 0;
+		mddev->level = LEVEL_NONE;
+		mddev->clevel[0] = 0;
+		mddev->flags = 0;
+		mddev->ro = 0;
+		mddev->metadata_type[0] = 0;
+		mddev->chunk_size = 0;
+		mddev->ctime = mddev->utime = 0;
+		mddev->layout = 0;
+		mddev->max_disks = 0;
+		mddev->events = 0;
+		mddev->delta_disks = 0;
+		mddev->new_level = LEVEL_NONE;
+		mddev->new_layout = 0;
+		mddev->new_chunk = 0;
+		mddev->curr_resync = 0;
+		mddev->resync_mismatches = 0;
+		mddev->suspend_lo = mddev->suspend_hi = 0;
+		mddev->sync_speed_min = mddev->sync_speed_max = 0;
+		mddev->recovery = 0;
+		mddev->in_sync = 0;
+		mddev->changed = 0;
+		mddev->degraded = 0;
+		mddev->barriers_work = 0;
+		mddev->safemode = 0;
 
 	} else if (mddev->pers)
 		printk(KERN_INFO "md: %s switched to read-only mode.\n",