[PATCH] s390: fail-fast requests on quiesced devices

Using the fail-fast flag in i/o requests on a dasd disk which has been
quiesced leads to kernel panics.  Modify the request start function to only
work on requests in a valid state.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 13 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 170aae004ceb..a3bfebcf31ef 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1257,25 +1257,28 @@ __dasd_start_head(struct dasd_device * device)
         if (list_empty(&device->ccw_queue))
                 return;
         cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
-        /* check FAILFAST */
+        if (cqr->status != DASD_CQR_QUEUED)
+                return;
+        /* Non-temporary stop condition will trigger fail fast */
         if (device->stopped & ~DASD_STOPPED_PENDING &&
             test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
             (!dasd_eer_enabled(device))) {
                 cqr->status = DASD_CQR_FAILED;
                 dasd_schedule_bh(device);
+                return;
         }
-        if ((cqr->status == DASD_CQR_QUEUED) &&
-            (!device->stopped)) {
-                /* try to start the first I/O that can be started */
-                rc = device->discipline->start_IO(cqr);
-                if (rc == 0)
-                        dasd_set_timer(device, cqr->expires);
-                else if (rc == -EACCES) {
-                        dasd_schedule_bh(device);
-                } else
-                        /* Hmpf, try again in 1/2 sec */
-                        dasd_set_timer(device, 50);
-        }
+        /* Don't try to start requests if device is stopped */
+        if (device->stopped)
+                return;
+
+        rc = device->discipline->start_IO(cqr);
+        if (rc == 0)
+                dasd_set_timer(device, cqr->expires);
+        else if (rc == -EACCES) {
+                dasd_schedule_bh(device);
+        } else
+                /* Hmpf, try again in 1/2 sec */
+                dasd_set_timer(device, 50);
 }
 
 /*