iscsi_ibft: Add prefix-len attr and display netmask

The iBFT table only specifies a prefix length, not a netmask.
And the netmask is pretty much pointless for IPv6.
So introduce a new attribute 'prefix-len'.

Some older user-space code might rely on the netmask attribute
being present, so we should always display it.

Changes from v1:
 - Combined two patches into one

Changes from v2:
 - Cleaned up/corrected wording for patch description

v3: [Put Hannes back as author]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Konrad Rzeszutek Wilk <konrad@kernel.org>

drivers/firmware/iscsi_ibft.c

@@ -319,6 +319,9 @@ static ssize_t ibft_attr_show_nic(void *data, int type, char *buf)
 		val = cpu_to_be32(~((1 << (32-nic->subnet_mask_prefix))-1));
 		str += sprintf(str, "%pI4", &val);
 		break;
+	case ISCSI_BOOT_ETH_PREFIX_LEN:
+		str += sprintf(str, "%d\n", nic->subnet_mask_prefix);
+		break;
 	case ISCSI_BOOT_ETH_ORIGIN:
 		str += sprintf(str, "%d\n", nic->origin);
 		break;
@@ -460,6 +463,7 @@ static umode_t ibft_check_nic_for(void *data, int type)
 		if (address_not_null(nic->ip_addr))
 			rc = S_IRUGO;
 		break;
+	case ISCSI_BOOT_ETH_PREFIX_LEN:
 	case ISCSI_BOOT_ETH_SUBNET_MASK:
 		if (nic->subnet_mask_prefix)
 			rc = S_IRUGO;

drivers/scsi/iscsi_boot_sysfs.c

@@ -166,6 +166,7 @@ static struct attribute_group iscsi_boot_target_attr_group = {
 iscsi_boot_rd_attr(eth_index, index, ISCSI_BOOT_ETH_INDEX);
 iscsi_boot_rd_attr(eth_flags, flags, ISCSI_BOOT_ETH_FLAGS);
 iscsi_boot_rd_attr(eth_ip, ip-addr, ISCSI_BOOT_ETH_IP_ADDR);
+iscsi_boot_rd_attr(eth_prefix, prefix-len, ISCSI_BOOT_ETH_PREFIX_LEN);
 iscsi_boot_rd_attr(eth_subnet, subnet-mask, ISCSI_BOOT_ETH_SUBNET_MASK);
 iscsi_boot_rd_attr(eth_origin, origin, ISCSI_BOOT_ETH_ORIGIN);
 iscsi_boot_rd_attr(eth_gateway, gateway, ISCSI_BOOT_ETH_GATEWAY);
@@ -181,6 +182,7 @@ static struct attribute *ethernet_attrs[] = {
 	&iscsi_boot_attr_eth_index.attr,
 	&iscsi_boot_attr_eth_flags.attr,
 	&iscsi_boot_attr_eth_ip.attr,
+	&iscsi_boot_attr_eth_prefix.attr,
 	&iscsi_boot_attr_eth_subnet.attr,
 	&iscsi_boot_attr_eth_origin.attr,
 	&iscsi_boot_attr_eth_gateway.attr,
@@ -208,6 +210,9 @@ static umode_t iscsi_boot_eth_attr_is_visible(struct kobject *kobj,
 	else if (attr ==  &iscsi_boot_attr_eth_ip.attr)
 		return boot_kobj->is_visible(boot_kobj->data,
 					     ISCSI_BOOT_ETH_IP_ADDR);
+	else if (attr ==  &iscsi_boot_attr_eth_prefix.attr)
+		return boot_kobj->is_visible(boot_kobj->data,
+					     ISCSI_BOOT_ETH_PREFIX_LEN);
 	else if (attr ==  &iscsi_boot_attr_eth_subnet.attr)
 		return boot_kobj->is_visible(boot_kobj->data,
 					     ISCSI_BOOT_ETH_SUBNET_MASK);

include/linux/iscsi_boot_sysfs.h

@@ -23,6 +23,7 @@ enum iscsi_boot_eth_properties_enum {
 	ISCSI_BOOT_ETH_INDEX,
 	ISCSI_BOOT_ETH_FLAGS,
 	ISCSI_BOOT_ETH_IP_ADDR,
+	ISCSI_BOOT_ETH_PREFIX_LEN,
 	ISCSI_BOOT_ETH_SUBNET_MASK,
 	ISCSI_BOOT_ETH_ORIGIN,
 	ISCSI_BOOT_ETH_GATEWAY,