[S390] dasd: automatic recognition of read-only devices

In z/VM it is possible to attach a device as read-only. To prevent
unintentional write requests and subsequent I/O errors, we can detect
this configuration using the z/VM DIAG 210 interface and set the
respective linux block device to read-only as well.

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/s390/block/dasd_genhd.c b/drivers/s390/block/dasd_genhd.c
index 94f92a1247f2..30a1ca3d08b7 100644
--- a/drivers/s390/block/dasd_genhd.c
+++ b/drivers/s390/block/dasd_genhd.c
@@ -70,7 +70,8 @@ int dasd_gendisk_alloc(struct dasd_block *block)
         }
         len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));
 
-        if (block->base->features & DASD_FEATURE_READONLY)
+        if (base->features & DASD_FEATURE_READONLY ||
+            test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
                 set_disk_ro(gdp, 1);
         gdp->private_data = block;
         gdp->queue = block->request_queue;