scsi/i2o: restore ioctl changes

This restores the changes from "scsi/i2o_block: cleanup ioctl
handling", which accidentally got reverted.

Origignal changelog:
      This fixes the ioctl function of the i2o_block driver, which
      has multiple problems:

      * The BLKI2OSRSTRAT and BLKI2OSWSTRAT commands always return
        -ENOTTY on success, where they should return 0.
      * Support for 32 bit compat is missing
      * The driver should use the .ioctl function and because
        .locked_ioctl is going away.

      The use of the big kernel lock remains for now, but gets
      made explictit in the ioctl function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/message/i2o/i2o_block.c

@@ -657,30 +657,40 @@ static int i2o_block_ioctl(struct block_device *bdev, fmode_t mode,
 {
 	struct gendisk *disk = bdev->bd_disk;
 	struct i2o_block_device *dev = disk->private_data;
+	int ret = -ENOTTY;
 
 	/* Anyone capable of this syscall can do *real bad* things */
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
+	lock_kernel();
 	switch (cmd) {
 	case BLKI2OGRSTRAT:
-		return put_user(dev->rcache, (int __user *)arg);
+		ret = put_user(dev->rcache, (int __user *)arg);
+		break;
 	case BLKI2OGWSTRAT:
-		return put_user(dev->wcache, (int __user *)arg);
+		ret = put_user(dev->wcache, (int __user *)arg);
+		break;
 	case BLKI2OSRSTRAT:
+		ret = -EINVAL;
 		if (arg < 0 || arg > CACHE_SMARTFETCH)
-			return -EINVAL;
+			break;
 		dev->rcache = arg;
+		ret = 0;
 		break;
 	case BLKI2OSWSTRAT:
+		ret = -EINVAL;
 		if (arg != 0
 		    && (arg < CACHE_WRITETHROUGH || arg > CACHE_SMARTBACK))
-			return -EINVAL;
+			break;
 		dev->wcache = arg;
+		ret = 0;
 		break;
 	}
-	return -ENOTTY;
+	unlock_kernel();
+
+	return ret;
 };
 
 /**
@@ -936,6 +946,7 @@ static const struct block_device_operations i2o_block_fops = {
 	.open = i2o_block_open,
 	.release = i2o_block_release,
 	.ioctl = i2o_block_ioctl,
+	.compat_ioctl = i2o_block_ioctl,
 	.getgeo = i2o_block_getgeo,
 	.media_changed = i2o_block_media_changed
 };