md raid0: access mddev->queue (request queue member) conditionally because it...

md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid

The patch makes 3 references to mddev->queue in the raid0 personality
conditional in order to allow for it to be accessed from dm-raid.
Mandatory, because md instances underneath dm-raid don't manage
a request queue of their own which'd lead to oopses without the patch.
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Tested-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid0.c

@@ -271,6 +271,7 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
 		goto abort;
 	}
 
+	if (mddev->queue) {
 		blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
 		blk_queue_io_opt(mddev->queue,
 				 (mddev->chunk_sectors << 9) * mddev->raid_disks);
@@ -279,6 +280,7 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
 			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 		else
 			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
+	}
 
 	pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 	*private_conf = conf;
@@ -429,9 +431,12 @@ static int raid0_run(struct mddev *mddev)
 	}
 	if (md_check_no_bitmap(mddev))
 		return -EINVAL;
+
+	if (mddev->queue) {
 		blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
+	}
 
 	/* if private is not null, we are here after takeover */
 	if (mddev->private == NULL) {
@@ -448,6 +453,8 @@ static int raid0_run(struct mddev *mddev)
 	printk(KERN_INFO "md/raid0:%s: md_size is %llu sectors.\n",
 	       mdname(mddev),
 	       (unsigned long long)mddev->array_sectors);
+
+	if (mddev->queue) {
 		/* calculate the max read-ahead size.
 		 * For read-ahead of large files to be effective, we need to
 		 * readahead at least twice a whole stripe. i.e. number of devices
@@ -457,7 +464,6 @@ static int raid0_run(struct mddev *mddev)
 		 * wants.  We consider this a configuration error: a larger
 		 * chunksize should be used in that case.
 		 */
-	{
 		int stripe = mddev->raid_disks *
 			(mddev->chunk_sectors << 9) / PAGE_SIZE;
 		if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)