From 33b62a30f78536b976183cc764c08038ac011e0a Mon Sep 17 00:00:00 2001
From: Stefan Weinhuber <wein@de.ibm.com>
Date: Mon, 8 Mar 2010 12:26:24 +0100
Subject: [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>
---
 drivers/s390/block/dasd_diag.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

(limited to 'drivers/s390/block/dasd_diag.c')

diff --git a/drivers/s390/block/dasd_diag.c b/drivers/s390/block/dasd_diag.c
index 6e14863f5c70..687f323cdc38 100644
--- a/drivers/s390/block/dasd_diag.c
+++ b/drivers/s390/block/dasd_diag.c
@@ -145,12 +145,10 @@ dasd_diag_erp(struct dasd_device *device)
 	mdsk_term_io(device);
 	rc = mdsk_init_io(device, device->block->bp_block, 0, NULL);
 	if (rc == 4) {
-		if (!(device->features & DASD_FEATURE_READONLY)) {
+		if (!(test_and_set_bit(DASD_FLAG_DEVICE_RO, &device->flags)))
 			pr_warning("%s: The access mode of a DIAG device "
 				   "changed to read-only\n",
 				   dev_name(&device->cdev->dev));
-			device->features |= DASD_FEATURE_READONLY;
-		}
 		rc = 0;
 	}
 	if (rc)
@@ -449,7 +447,7 @@ dasd_diag_check_device(struct dasd_device *device)
 		rc = -EIO;
 	} else {
 		if (rc == 4)
-			device->features |= DASD_FEATURE_READONLY;
+			set_bit(DASD_FLAG_DEVICE_RO, &device->flags);
 		pr_info("%s: New DASD with %ld byte/block, total size %ld "
 			"KB%s\n", dev_name(&device->cdev->dev),
 			(unsigned long) block->bp_block,
-- 
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