md: suspend i/o during runtime blk_integrity_unregister

Synchronize pending i/o against a change in the integrity profile to
avoid the possibility of spurious integrity errors.  Given linear_add()
is suspending the mddev before manipulating the mddev, do the same for
the other personalities.
Acked-by: NeilBrown <neilb@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/md/md.c

@@ -1994,6 +1994,7 @@ void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
 	if (bi_rdev && blk_integrity_compare(mddev->gendisk,
 					     rdev->bdev->bd_disk) >= 0)
 		return;
+	WARN_ON_ONCE(!mddev->suspended);
 	printk(KERN_NOTICE "disabling data integrity on %s\n", mdname(mddev));
 	blk_integrity_unregister(mddev->gendisk);
 }

drivers/md/multipath.c

@@ -264,7 +264,9 @@ static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 			spin_unlock_irq(&conf->device_lock);
 			rcu_assign_pointer(p->rdev, rdev);
 			err = 0;
+			mddev_suspend(mddev);
 			md_integrity_add_rdev(rdev, mddev);
+			mddev_resume(mddev);
 			break;
 		}
 

drivers/md/raid1.c

@@ -1621,7 +1621,9 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 			break;
 		}
 	}
+	mddev_suspend(mddev);
 	md_integrity_add_rdev(rdev, mddev);
+	mddev_resume(mddev);
 	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 	print_conf(conf);

drivers/md/raid10.c

@@ -1736,7 +1736,9 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 		rcu_assign_pointer(p->rdev, rdev);
 		break;
 	}
+	mddev_suspend(mddev);
 	md_integrity_add_rdev(rdev, mddev);
+	mddev_resume(mddev);
 	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);