nbd: use the structured req attr check

Use the macro for checking presence of required attributes.
It has the advantage of reporting to the user which attr
was missing in a machine-readable format (extack).
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20230224021301.1630703-2-kuba@kernel.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/nbd.c

@@ -1934,11 +1934,11 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
 			return -EINVAL;
 		}
 	}
-	if (!info->attrs[NBD_ATTR_SOCKETS]) {
+	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_SOCKETS)) {
 		pr_err("must specify at least one socket\n");
 		return -EINVAL;
 	}
-	if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
+	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_SIZE_BYTES)) {
 		pr_err("must specify a size in bytes for the device\n");
 		return -EINVAL;
 	}
@@ -2123,7 +2123,7 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
 	if (!netlink_capable(skb, CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (!info->attrs[NBD_ATTR_INDEX]) {
+	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_INDEX)) {
 		pr_err("must specify an index to disconnect\n");
 		return -EINVAL;
 	}
@@ -2161,7 +2161,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
 	if (!netlink_capable(skb, CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (!info->attrs[NBD_ATTR_INDEX]) {
+	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_INDEX)) {
 		pr_err("must specify a device to reconfigure\n");
 		return -EINVAL;
 	}