[patch 08/52] [PATCH] dasd: support DIAG access for read-only devices

Martin Schwidefsky
2009-11-13T15:16:55Z

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From: Stefan Weinhuber <wein@de.ibm.com>

When a DASD device is used with the DIAG discipline, the DIAG
initialization will indicate success or error with a respective
return code. So far we have interpreted a return code of 4 as error,
but it actually means that the initialization was successful, but
the device is read-only. To allow read-only devices to be used with
DIAG we need to accept a return code of 4 as success.

Re-initialization of the DIAG access is also part of the DIAG error
recovery. If we find that the access mode of a device has been
changed from writable to read-only while the device was in use,
we print an error message.

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

drivers/s390/block/dasd_diag.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)

Index: quilt-2.6/drivers/s390/block/dasd_diag.c
===================================================================
--- quilt-2.6.orig/drivers/s390/block/dasd_diag.c 2009-11-13 15:48:33.000000000 +0100
+++ quilt-2.6/drivers/s390/block/dasd_diag.c 2009-11-13 16:08:13.000000000 +0100
@@ -145,6 +145,15 @@

mdsk_term_io(device);
rc = mdsk_init_io(device, device->block->bp_block, 0, NULL);
+ if (rc == 4) {
+ if (!(device->features & DASD_FEATURE_READONLY)) {
+ dev_warn(&device->cdev->dev,
+ "The access mode of a DIAG device changed"
+ " to read-only");
+ device->features |= DASD_FEATURE_READONLY;
+ }
+ rc = 0;
+ }
if (rc)
dev_warn(&device->cdev->dev, "DIAG ERP failed with "
"rc=%d\n", rc);
@@ -433,16 +442,20 @@
for (sb = 512; sb < bsize; sb = sb << 1)
block->s2b_shift++;
rc = mdsk_init_io(device, block->bp_block, 0, NULL);
- if (rc) {
+ if (rc && (rc != 4)) {
dev_warn(&device->cdev->dev, "DIAG initialization "
"failed with rc=%d\n", rc);
rc = -EIO;
} else {
+ if (rc == 4)
+ device->features |= DASD_FEATURE_READONLY;
dev_info(&device->cdev->dev,
- "New DASD with %ld byte/block, total size %ld KB\n",
+ "New DASD with %ld byte/block, total size %ld KB%s\n",
(unsigned long) block->bp_block,
(unsigned long) (block->blocks <<
- block->s2b_shift) >> 1);
+ block->s2b_shift) >> 1,
+ (rc == 4) ? ", read-only device" : "");
+ rc = 0;
}
out_label:
free_page((long) label);