1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7bcc1d8bc967..8299e2d3b611 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device *lo)
 	ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 	if (ret) {
 		printk(KERN_ERR "nbd: sysfs_create_file failed!");
+		lo->pid = 0;
 		return ret;
 	}
 
@@ -413,6 +414,7 @@ static int nbd_do_it(struct nbd_device *lo)
 		nbd_end_request(req);
 
 	sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
+	lo->pid = 0;
 	return 0;
 }
 
@@ -547,6 +549,15 @@ static void do_nbd_request(struct request_queue * q)
 
 		BUG_ON(lo->magic != LO_MAGIC);
 
+		if (unlikely(!lo->sock)) {
+			printk(KERN_ERR "%s: Attempted send on closed socket\n",
+				lo->disk->disk_name);
+			req->errors++;
+			nbd_end_request(req);
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
 		spin_lock_irq(&lo->queue_lock);
 		list_add_tail(&req->queuelist, &lo->waiting_queue);
 		spin_unlock_irq(&lo->queue_lock);
@@ -648,6 +659,8 @@ static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 		set_capacity(lo->disk, lo->bytesize >> 9);
 		return 0;
 	case NBD_DO_IT:
+		if (lo->pid)
+			return -EBUSY;
 		if (!lo->file)
 			return -EINVAL;
 		thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);