From: Stefan Haberland <sth@linux.vnet.ibm.com>
Date: Thu, 26 Oct 2017 14:37:35 +0200
Subject: s390/dasd: prevent prefix I/O error
Git-commit: da340f921d3454f1521671c7a5a43ad3331fbe50
Patch-mainline: v4.15-rc3
References: bsc#1103421

Prevent that a prefix flag is set based on invalid configuration data.
The validity.verify_base flag should only be set for alias devices.
Usually the unit address type is either one of base, PAV alias or
HyperPAV alias. But in cases where the unit address type is not set or
any other value the validity.verify_base flag might be set as well.
This would lead to follow on errors.
Explicitly check for alias devices and set the validity flag only for
them.

Signed-off-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/s390/block/dasd_eckd.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -521,10 +521,12 @@ static int prefix_LRE(struct ccw1 *ccw,
 	pfxdata->validity.define_extent = 1;
 
 	/* private uid is kept up to date, conf_data may be outdated */
-	if (startpriv->uid.type != UA_BASE_DEVICE) {
+	if (startpriv->uid.type == UA_BASE_PAV_ALIAS)
 		pfxdata->validity.verify_base = 1;
-		if (startpriv->uid.type == UA_HYPER_PAV_ALIAS)
-			pfxdata->validity.hyper_pav = 1;
+
+	if (startpriv->uid.type == UA_HYPER_PAV_ALIAS) {
+		pfxdata->validity.verify_base = 1;
+		pfxdata->validity.hyper_pav = 1;
 	}
 
 	/* define extend data (mostly)*/
@@ -3488,10 +3490,12 @@ static int prepare_itcw(struct itcw *itc
 	pfxdata.validity.define_extent = 1;
 
 	/* private uid is kept up to date, conf_data may be outdated */
-	if (startpriv->uid.type != UA_BASE_DEVICE) {
+	if (startpriv->uid.type == UA_BASE_PAV_ALIAS)
+		pfxdata.validity.verify_base = 1;
+
+	if (startpriv->uid.type == UA_HYPER_PAV_ALIAS) {
 		pfxdata.validity.verify_base = 1;
-		if (startpriv->uid.type == UA_HYPER_PAV_ALIAS)
-			pfxdata.validity.hyper_pav = 1;
+		pfxdata.validity.hyper_pav = 1;
 	}
 
 	switch (cmd) {