+static int rbd_ioctl_set_ro(struct rbd_device *rbd_dev, unsigned long arg)
+{
+ int ret = 0;
+ int val;
+ bool ro;
+ bool ro_changed = false;
+
+ /* get_user() may sleep, so call it before taking rbd_dev->lock */
+ if (get_user(val, (int __user *)(arg)))
+ return -EFAULT;
+
+ ro = val ? true : false;
+ /* Snapshot doesn't allow to write*/
+ if (rbd_dev->spec->snap_id != CEPH_NOSNAP && !ro)
+ return -EROFS;
+
+ spin_lock_irq(&rbd_dev->lock);
+ /* prevent others open this device */
+ if (rbd_dev->open_count > 1) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ if (rbd_dev->mapping.read_only != ro) {
+ rbd_dev->mapping.read_only = ro;
+ ro_changed = true;
+ }
+
+out:
+ spin_unlock_irq(&rbd_dev->lock);
+ /* set_disk_ro() may sleep, so call it after releasing rbd_dev->lock */
+ if (ret == 0 && ro_changed)
+ set_disk_ro(rbd_dev->disk, ro ? 1 : 0);
+
+ return ret;
+}
+
+static int rbd_ioctl(struct block_device *bdev, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
+ int ret = 0;
+
+ switch (cmd) {
+ case BLKROSET:
+ ret = rbd_ioctl_set_ro(rbd_dev, arg);
+ break;
+ default:
+ ret = -ENOTTY;
+ }
+
+ return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static int rbd_compat_ioctl(struct block_device *bdev, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ return rbd_ioctl(bdev, mode, cmd, arg);
+}
+#endif /* CONFIG_COMPAT */
+