dasd: implement ->set_read_only to hook into BLKROSET processing

Implement the ->set_read_only method instead of parsing the actual
ioctl command.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/s390/block/dasd.c

@@ -3394,6 +3394,7 @@ dasd_device_operations = {
 	.ioctl		= dasd_ioctl,
 	.compat_ioctl	= dasd_ioctl,
 	.getgeo		= dasd_getgeo,
+	.set_read_only	= dasd_set_read_only,
 };
 
 /*******************************************************************************

drivers/s390/block/dasd_int.h

@@ -844,7 +844,8 @@ int dasd_scan_partitions(struct dasd_block *);
 void dasd_destroy_partitions(struct dasd_block *);
 
 /* externals in dasd_ioctl.c */
-int  dasd_ioctl(struct block_device *, fmode_t, unsigned int, unsigned long);
+int dasd_ioctl(struct block_device *, fmode_t, unsigned int, unsigned long);
+int dasd_set_read_only(struct block_device *bdev, bool ro);
 
 /* externals in dasd_proc.c */
 int dasd_proc_init(void);

drivers/s390/block/dasd_ioctl.c

@@ -532,28 +532,22 @@ static int dasd_ioctl_information(struct dasd_block *block, void __user *argp,
 /*
  * Set read only
  */
-static int
-dasd_ioctl_set_ro(struct block_device *bdev, void __user *argp)
+int dasd_set_read_only(struct block_device *bdev, bool ro)
 {
 	struct dasd_device *base;
-	int intval, rc;
+	int rc;
 
-	if (!capable(CAP_SYS_ADMIN))
-		return -EACCES;
+	/* do not manipulate hardware state for partitions */
 	if (bdev_is_partition(bdev))
-		// ro setting is not allowed for partitions
-		return -EINVAL;
-	if (get_user(intval, (int __user *)argp))
-		return -EFAULT;
+		return 0;
+
 	base = dasd_device_from_gendisk(bdev->bd_disk);
 	if (!base)
 		return -ENODEV;
-	if (!intval && test_bit(DASD_FLAG_DEVICE_RO, &base->flags)) {
-		dasd_put_device(base);
-		return -EROFS;
-	}
-	set_disk_ro(bdev->bd_disk, intval);
-	rc = dasd_set_feature(base->cdev, DASD_FEATURE_READONLY, intval);
+	if (!ro && test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
+		rc = -EROFS;
+	else
+		rc = dasd_set_feature(base->cdev, DASD_FEATURE_READONLY, ro);
 	dasd_put_device(base);
 	return rc;
 }
@@ -633,9 +627,6 @@ int dasd_ioctl(struct block_device *bdev, fmode_t mode,
 	case BIODASDPRRST:
 		rc = dasd_ioctl_reset_profile(block);
 		break;
-	case BLKROSET:
-		rc = dasd_ioctl_set_ro(bdev, argp);
-		break;
 	case DASDAPIVER:
 		rc = dasd_ioctl_api_version(argp);
 		break;