[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, 4 insertions, 2 deletions

diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index 7039d9cf0fb4..3479f8158a1b 100644
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -199,7 +199,8 @@ dasd_ioctl_format(struct block_device *bdev, void __user *argp)
         if (!argp)
                 return -EINVAL;
 
-        if (block->base->features & DASD_FEATURE_READONLY)
+        if (block->base->features & DASD_FEATURE_READONLY ||
+            test_bit(DASD_FLAG_DEVICE_RO, &block->base->flags))
                 return -EROFS;
         if (copy_from_user(&fdata, argp, sizeof(struct format_data_t)))
                 return -EFAULT;
@@ -349,7 +350,8 @@ dasd_ioctl_set_ro(struct block_device *bdev, void __user *argp)
                 return -EINVAL;
         if (get_user(intval, (int __user *)argp))
                 return -EFAULT;
-
+        if (!intval && test_bit(DASD_FLAG_DEVICE_RO, &block->base->flags))
+                return -EROFS;
         set_disk_ro(bdev->bd_disk, intval);
         return dasd_set_feature(block->base->cdev, DASD_FEATURE_READONLY, intval);
 }