From: Hans-Joachim Picht <hpicht@redhat.com>
Date: Tue, 22 Sep 2009 22:13:37 +0200
Subject: [s390] dasd: fail requests when dev state is not ready
Message-id: 20090922201337.GC32244@blc4eb509856389.ibm.com
O-Subject: [RHEL5 U5 PATCH 1/1] s390 - dasd: fail requests when device state is less then ready
Bugzilla: 523219
RH-Acked-by: Pete Zaitcev <zaitcev@redhat.com>

Description
===========
Device mapper multipath device blocks when one path is set to state 'basic'

In certain device mapper multipath / PPRC setups a DASD device
gets quiesced and then set to state basic to flush it's queue
and return all already queued requests back to device mapper.
Sometimes it can happen that a request is queued after
the device was set to basic, so that requests stays queued,
is not processed and device mapper is blocked waiting for it.

Solution: A DASD device that is not ready or online has no defined
disk layout, so all requests that arrive in such a state
need to be returned as failed.

Bugzilla
========

BZ 523219
https://bugzilla.redhat.com/show_bug.cgi?id=523219

Upstream status of the patch
============================

The patch will be upstream as of kernel version 2.6.32

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=97f604b07473669f4da52b1f859ee45e8d48d42a

Test status
===========

The patch has been tested and fixes the problem.
The fix has been verified by the IBM test department.

Please ACK.

With best regards,

        Hans

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 17c7224..2ad10fb 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -267,12 +267,12 @@ dasd_state_ready_to_basic(struct dasd_device * device)
 	rc = dasd_flush_ccw_queue(device, 0);
 	if (rc)
 		return rc;
+	device->state = DASD_STATE_BASIC;
 	dasd_destroy_partitions(device);
 	dasd_flush_request_queue(device);
 	device->blocks = 0;
 	device->bp_block = 0;
 	device->s2b_shift = 0;
-	device->state = DASD_STATE_BASIC;
 	return 0;
 }
 
@@ -1210,9 +1210,14 @@ __dasd_process_blk_queue(struct dasd_device * device)
 	 * for that. State DASD_STATE_ONLINE is normal block device
 	 * operation.
 	 */
-	if (device->state != DASD_STATE_READY &&
-	    device->state != DASD_STATE_ONLINE)
+	if (device->state < DASD_STATE_READY) {
+		while ((req = elv_next_request(queue))) {
+			blkdev_dequeue_request(req);
+			dasd_end_request(req, 0);
+		}
 		return;
+	}
+
 	nr_queued = 0;
 	/* Now we try to fetch requests from the request queue */
 	list_for_each_entry(cqr, &device->ccw_queue, list)