md: make sure everything is freed when dm-raid stops an array.

md_stop() would stop an array, but not free various attached
data structures.
For internal arrays, these are freed later in do_md_stop() or
mddev_put(), but they don't apply for dm-raid arrays.
So get md_stop() to free them, and only all it from dm-raid.
For internal arrays we now call __md_stop.
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -5294,7 +5294,7 @@ void md_stop_writes(struct mddev *mddev)
 }
 EXPORT_SYMBOL_GPL(md_stop_writes);
 
-void md_stop(struct mddev *mddev)
+static void __md_stop(struct mddev *mddev)
 {
 	mddev->ready = 0;
 	mddev->pers->stop(mddev);
@@ -5304,6 +5304,18 @@ void md_stop(struct mddev *mddev)
 	mddev->pers = NULL;
 	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 }
+
+void md_stop(struct mddev *mddev)
+{
+	/* stop the array and free an attached data structures.
+	 * This is called from dm-raid
+	 */
+	__md_stop(mddev);
+	bitmap_destroy(mddev);
+	if (mddev->bio_set)
+		bioset_free(mddev->bio_set);
+}
+
 EXPORT_SYMBOL_GPL(md_stop);
 
 static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
@@ -5364,7 +5376,7 @@ static int do_md_stop(struct mddev * mddev, int mode,
 			set_disk_ro(disk, 0);
 
 		__md_stop_writes(mddev);
-		md_stop(mddev);
+		__md_stop(mddev);
 		mddev->queue->merge_bvec_fn = NULL;
 		mddev->queue->backing_dev_info.congested_fn = NULL;