+static long loop_control_ioctl(struct file *file, unsigned int cmd,
+ unsigned long parm)
+{
+ struct loop_device *lo;
+ int ret = -ENOSYS;
+
+ mutex_lock(&loop_index_mutex);
+ switch (cmd) {
+ case LOOP_CTL_ADD:
+ ret = loop_lookup(&lo, parm);
+ if (ret >= 0) {
+ ret = -EEXIST;
+ break;
+ }
+ ret = loop_add(&lo, parm);
+ break;
+ case LOOP_CTL_REMOVE:
+ ret = loop_lookup(&lo, parm);
+ if (ret < 0)
+ break;
+ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_state != Lo_unbound) {
+ ret = -EBUSY;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ if (lo->lo_refcnt > 0) {
+ ret = -EBUSY;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ lo->lo_disk->private_data = NULL;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ idr_remove(&loop_index_idr, lo->lo_number);
+ loop_remove(lo);
+ break;
+ case LOOP_CTL_GET_FREE:
+ ret = loop_lookup(&lo, -1);
+ if (ret >= 0)
+ break;
+ ret = loop_add(&lo, -1);
+ }
+ mutex_unlock(&loop_index_mutex);
+
+ return ret;
+}
+
+static const struct file_operations loop_ctl_fops = {
+ .open = nonseekable_open,
+ .unlocked_ioctl = loop_control_ioctl,
+ .compat_ioctl = loop_control_ioctl,
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+};
+
+static struct miscdevice loop_misc = {
+ .minor = LOOP_CTRL_MINOR,
+ .name = "loop-control",
+ .fops = &loop_ctl_fops,
+};
+
+MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
+MODULE_ALIAS("devname:loop-control");
+