rbd: add ioctl for rbd

When running the following commands:
    [root@ceph0 mnt]# blockdev --setro /dev/rbd1
    [root@ceph0 mnt]# blockdev --getro /dev/rbd1
    0

The block setro didn't take effect, it is because
the rbd doesn't support ioctl of block driver.

This resolves:
	http://tracker.ceph.com/issues/6265

Signed-off-by: Guangliang Zhao <guangliang@unitedstack.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 60 insertions, 2 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 8295b3afa8e0..1c88fba98c8e 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -559,10 +559,69 @@ static void rbd_release(struct gendisk *disk, fmode_t mode)
         put_device(&rbd_dev->dev);
 }
 
+static int rbd_ioctl_set_ro(struct rbd_device *rbd_dev, unsigned long arg)
+{
+        int val;
+        bool ro;
+
+        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;
+
+        if (rbd_dev->mapping.read_only != ro) {
+                rbd_dev->mapping.read_only = ro;
+                set_disk_ro(rbd_dev->disk, ro ? 1 : 0);
+        }
+
+        return 0;
+}
+
+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;
+
+        spin_lock_irq(&rbd_dev->lock);
+        /* prevent others open this device */
+        if (rbd_dev->open_count > 1) {
+                ret = -EBUSY;
+                goto out;
+        }
+
+        switch (cmd) {
+        case BLKROSET:
+                ret = rbd_ioctl_set_ro(rbd_dev, arg);
+                break;
+        default:
+                ret = -ENOTTY;
+        }
+
+out:
+        spin_unlock_irq(&rbd_dev->lock);
+        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 */
+
 static const struct block_device_operations rbd_bd_ops = {
         .owner                  = THIS_MODULE,
         .open                   = rbd_open,
         .release                = rbd_release,
+        .ioctl                  = rbd_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl           = rbd_compat_ioctl,
+#endif
 };
 
 /*
@@ -3114,7 +3173,6 @@ static void rbd_request_fn(struct request_queue *q)
                 __releases(q->queue_lock) __acquires(q->queue_lock)
 {
         struct rbd_device *rbd_dev = q->queuedata;
-        bool read_only = rbd_dev->mapping.read_only;
         struct request *rq;
         int result;
 
@@ -3150,7 +3208,7 @@ static void rbd_request_fn(struct request_queue *q)
 
                 if (write_request) {
                         result = -EROFS;
-                        if (read_only)
+                        if (rbd_dev->mapping.read_only)
                                 goto end_request;
                         rbd_assert(rbd_dev->spec->snap_id == CEPH_NOSNAP);
                 }