block: don't call into the driver for BLKROSET

Now that all drivers that want to hook into setting or clearing the
read-only flag use the set_read_only method, this code can be removed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/ioctl.c

@@ -346,26 +346,6 @@ static int blkdev_pr_clear(struct block_device *bdev,
 	return ops->pr_clear(bdev, c.key);
 }
 
-/*
- * Is it an unrecognized ioctl? The correct returns are either
- * ENOTTY (final) or ENOIOCTLCMD ("I don't know this one, try a
- * fallback"). ENOIOCTLCMD gets turned into ENOTTY by the ioctl
- * code before returning.
- *
- * Confused drivers sometimes return EINVAL, which is wrong. It
- * means "I understood the ioctl command, but the parameters to
- * it were wrong".
- *
- * We should aim to just fix the broken drivers, the EINVAL case
- * should go away.
- */
-static inline int is_unrecognized_ioctl(int ret)
-{
-	return	ret == -EINVAL ||
-		ret == -ENOTTY ||
-		ret == -ENOIOCTLCMD;
-}
-
 static int blkdev_flushbuf(struct block_device *bdev, fmode_t mode,
 		unsigned cmd, unsigned long arg)
 {
@@ -384,9 +364,6 @@ static int blkdev_roset(struct block_device *bdev, fmode_t mode,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
-	ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
-	if (!is_unrecognized_ioctl(ret))
-		return ret;
 	if (get_user(n, (int __user *)arg))
 		return -EFAULT;
 	if (bdev->bd_disk->fops->set_read_only) {