s390/dasd: Implement block timeout handling

This patch implements generic block layer timeout handling
callbacks for DASDs. When the timeout expires the respective
cqr is aborted.

With this timeout handler time-critical request abort
is guaranteed as the abort does not depend on the internal
state of the various DASD driver queues.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Acked-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

4 files changed, 88 insertions, 2 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 000e5140bda4..87478becedb0 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -2573,8 +2573,10 @@ static void __dasd_process_request_queue(struct dasd_block *block)
                  */
                 cqr->callback_data = (void *) req;
                 cqr->status = DASD_CQR_FILLED;
+                req->completion_data = cqr;
                 blk_start_request(req);
                 list_add_tail(&cqr->blocklist, &block->ccw_queue);
+                INIT_LIST_HEAD(&cqr->devlist);
                 dasd_profile_start(block, cqr, req);
         }
 }
@@ -2862,6 +2864,80 @@ static void do_dasd_request(struct request_queue *queue)
 }
 
 /*
+ * Block timeout callback, called from the block layer
+ *
+ * request_queue lock is held on entry.
+ *
+ * Return values:
+ * BLK_EH_RESET_TIMER if the request should be left running
+ * BLK_EH_NOT_HANDLED if the request is handled or terminated
+ *                    by the driver.
+ */
+enum blk_eh_timer_return dasd_times_out(struct request *req)
+{
+        struct dasd_ccw_req *cqr = req->completion_data;
+        struct dasd_block *block = req->q->queuedata;
+        struct dasd_device *device;
+        int rc = 0;
+
+        if (!cqr)
+                return BLK_EH_NOT_HANDLED;
+
+        device = cqr->startdev ? cqr->startdev : block->base;
+        DBF_DEV_EVENT(DBF_WARNING, device,
+                      " dasd_times_out cqr %p status %x",
+                      cqr, cqr->status);
+
+        spin_lock(&block->queue_lock);
+        spin_lock(get_ccwdev_lock(device->cdev));
+        cqr->retries = -1;
+        cqr->intrc = -ETIMEDOUT;
+        if (cqr->status >= DASD_CQR_QUEUED) {
+                spin_unlock(get_ccwdev_lock(device->cdev));
+                rc = dasd_cancel_req(cqr);
+        } else if (cqr->status == DASD_CQR_FILLED ||
+                   cqr->status == DASD_CQR_NEED_ERP) {
+                cqr->status = DASD_CQR_TERMINATED;
+                spin_unlock(get_ccwdev_lock(device->cdev));
+        } else if (cqr->status == DASD_CQR_IN_ERP) {
+                struct dasd_ccw_req *searchcqr, *nextcqr, *tmpcqr;
+
+                list_for_each_entry_safe(searchcqr, nextcqr,
+                                         &block->ccw_queue, blocklist) {
+                        tmpcqr = searchcqr;
+                        while (tmpcqr->refers)
+                                tmpcqr = tmpcqr->refers;
+                        if (tmpcqr != cqr)
+                                continue;
+                        /* searchcqr is an ERP request for cqr */
+                        searchcqr->retries = -1;
+                        searchcqr->intrc = -ETIMEDOUT;
+                        if (searchcqr->status >= DASD_CQR_QUEUED) {
+                                spin_unlock(get_ccwdev_lock(device->cdev));
+                                rc = dasd_cancel_req(searchcqr);
+                                spin_lock(get_ccwdev_lock(device->cdev));
+                        } else if ((searchcqr->status == DASD_CQR_FILLED) ||
+                                   (searchcqr->status == DASD_CQR_NEED_ERP)) {
+                                searchcqr->status = DASD_CQR_TERMINATED;
+                                rc = 0;
+                        } else if (searchcqr->status == DASD_CQR_IN_ERP) {
+                                /*
+                                 * Shouldn't happen; most recent ERP
+                                 * request is at the front of queue
+                                 */
+                                continue;
+                        }
+                        break;
+                }
+                spin_unlock(get_ccwdev_lock(device->cdev));
+        }
+        dasd_schedule_block_bh(block);
+        spin_unlock(&block->queue_lock);
+
+        return rc ? BLK_EH_RESET_TIMER : BLK_EH_NOT_HANDLED;
+}
+
+/*
  * Allocate and initialize request queue and default I/O scheduler.
  */
 static int dasd_alloc_queue(struct dasd_block *block)
diff --git a/drivers/s390/block/dasd_diag.c b/drivers/s390/block/dasd_diag.c
index 154842242c3d..feca317b33de 100644
--- a/drivers/s390/block/dasd_diag.c
+++ b/drivers/s390/block/dasd_diag.c
@@ -583,7 +583,10 @@ dasd_diag_free_cp(struct dasd_ccw_req *cqr, struct request *req)
 
 static void dasd_diag_handle_terminated_request(struct dasd_ccw_req *cqr)
 {
-        cqr->status = DASD_CQR_FILLED;
+        if (cqr->retries < 0)
+                cqr->status = DASD_CQR_FAILED;
+        else
+                cqr->status = DASD_CQR_FILLED;
 };
 
 /* Fill in IOCTL data for device. */
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 05f5694c9c49..e61a6deea3c0 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -2381,6 +2381,10 @@ sleep:
 
 static void dasd_eckd_handle_terminated_request(struct dasd_ccw_req *cqr)
 {
+        if (cqr->retries < 0) {
+                cqr->status = DASD_CQR_FAILED;
+                return;
+        }
         cqr->status = DASD_CQR_FILLED;
         if (cqr->block && (cqr->startdev != cqr->block->base)) {
                 dasd_eckd_reset_ccw_to_base_io(cqr);
diff --git a/drivers/s390/block/dasd_fba.c b/drivers/s390/block/dasd_fba.c
index d232c83ea95a..9cbc8c32ba59 100644
--- a/drivers/s390/block/dasd_fba.c
+++ b/drivers/s390/block/dasd_fba.c
@@ -428,7 +428,10 @@ out:
 
 static void dasd_fba_handle_terminated_request(struct dasd_ccw_req *cqr)
 {
-        cqr->status = DASD_CQR_FILLED;
+        if (cqr->retries < 0)
+                cqr->status = DASD_CQR_FAILED;
+        else
+                cqr->status = DASD_CQR_FILLED;
 };
 
 static int