s390/block/dasd_genhd: add error handling support for add_disk()

We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.

Be sure to call dasd_gendisk_free() on error.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210927220232.1071926-5-mcgrof@kernel.orgSigned-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

drivers/s390/block/dasd_genhd.c

@@ -33,7 +33,7 @@ int dasd_gendisk_alloc(struct dasd_block *block)
 {
 	struct gendisk *gdp;
 	struct dasd_device *base;
-	int len;
+	int len, rc;
 
 	/* Make sure the minor for this device exists. */
 	base = block->base;
@@ -79,7 +79,13 @@ int dasd_gendisk_alloc(struct dasd_block *block)
 	dasd_add_link_to_gendisk(gdp, base);
 	block->gdp = gdp;
 	set_capacity(block->gdp, 0);
-	device_add_disk(&base->cdev->dev, block->gdp, NULL);
+
+	rc = device_add_disk(&base->cdev->dev, block->gdp, NULL);
+	if (rc) {
+		dasd_gendisk_free(block);
+		return rc;
+	}
+
 	return 0;
 }