s390/dasd: fix unresumed device after suspend/resume

The DASD device driver only has a limited amount of memory to build
I/O requests.
This memory was used by blocklayer requests leading to an inability
to build needed internal requests to resume the device.
Fix by preventing the DASD driver to fetch requests for a stopped
device.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Reference-ID: RQM 2520
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/block/dasd.c

@@ -2527,6 +2527,11 @@ static void __dasd_process_request_queue(struct dasd_block *block)
 			__blk_end_request_all(req, -EIO);
 		return;
 	}
+
+	/* if device ist stopped do not fetch new requests */
+	if (basedev->stopped)
+		return;
+
 	/* Now we try to fetch requests from the request queue */
 	while ((req = blk_peek_request(queue))) {
 		if (basedev->features & DASD_FEATURE_READONLY &&