[S390] dasd: improve error recovery for internal I/O

Most of the error conditions reported by a FICON storage server
indicate situations which can be recovered. Sometimes the host just
needs to retry an I/O request, but sometimes the recovery
is more complex and requires the device driver to wait, choose
a different path, etc.

The DASD device driver has a fully featured error recovery
for normal block layer I/O, but not for internal I/O request which
are for example used during the device bring up.
This can lead to situations where the IPL of a system fails because
DASD devices are not properly recognized.
This patch will extend the internal I/O handling to use the existing
error recovery procedures.

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

1 files changed, 152 insertions, 55 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 329115a4d4b3..4f211c175b55 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -63,6 +63,7 @@ static void do_restore_device(struct work_struct *);
 static void dasd_return_cqr_cb(struct dasd_ccw_req *, void *);
 static void dasd_device_timeout(unsigned long);
 static void dasd_block_timeout(unsigned long);
+static void __dasd_process_erp(struct dasd_device *, struct dasd_ccw_req *);
 
 /*
  * SECTION: Operations on the device structure.
@@ -959,7 +960,7 @@ static void dasd_device_timeout(unsigned long ptr)
         device = (struct dasd_device *) ptr;
         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
         /* re-activate request queue */
-        device->stopped &= ~DASD_STOPPED_PENDING;
+        dasd_device_remove_stop_bits(device, DASD_STOPPED_PENDING);
         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
         dasd_schedule_device_bh(device);
 }
@@ -1022,7 +1023,7 @@ void dasd_generic_handle_state_change(struct dasd_device *device)
         /* First of all start sense subsystem status request. */
         dasd_eer_snss(device);
 
-        device->stopped &= ~DASD_STOPPED_PENDING;
+        dasd_device_remove_stop_bits(device, DASD_STOPPED_PENDING);
         dasd_schedule_device_bh(device);
         if (device->block)
                 dasd_schedule_block_bh(device->block);
@@ -1404,6 +1405,20 @@ void dasd_schedule_device_bh(struct dasd_device *device)
         tasklet_hi_schedule(&device->tasklet);
 }
 
+void dasd_device_set_stop_bits(struct dasd_device *device, int bits)
+{
+        device->stopped |= bits;
+}
+EXPORT_SYMBOL_GPL(dasd_device_set_stop_bits);
+
+void dasd_device_remove_stop_bits(struct dasd_device *device, int bits)
+{
+        device->stopped &= ~bits;
+        if (!device->stopped)
+                wake_up(&generic_waitq);
+}
+EXPORT_SYMBOL_GPL(dasd_device_remove_stop_bits);
+
 /*
  * Queue a request to the head of the device ccw_queue.
  * Start the I/O if possible.
@@ -1464,58 +1479,135 @@ static inline int _wait_for_wakeup(struct dasd_ccw_req *cqr)
 }
 
 /*
- * Queue a request to the tail of the device ccw_queue and wait for
- * it's completion.
+ * checks if error recovery is necessary, returns 1 if yes, 0 otherwise.
  */
-int dasd_sleep_on(struct dasd_ccw_req *cqr)
+static int __dasd_sleep_on_erp(struct dasd_ccw_req *cqr)
 {
         struct dasd_device *device;
-        int rc;
+        dasd_erp_fn_t erp_fn;
 
+        if (cqr->status == DASD_CQR_FILLED)
+                return 0;
         device = cqr->startdev;
+        if (test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags)) {
+                if (cqr->status == DASD_CQR_TERMINATED) {
+                        device->discipline->handle_terminated_request(cqr);
+                        return 1;
+                }
+                if (cqr->status == DASD_CQR_NEED_ERP) {
+                        erp_fn = device->discipline->erp_action(cqr);
+                        erp_fn(cqr);
+                        return 1;
+                }
+                if (cqr->status == DASD_CQR_FAILED)
+                        dasd_log_sense(cqr, &cqr->irb);
+                if (cqr->refers) {
+                        __dasd_process_erp(device, cqr);
+                        return 1;
+                }
+        }
+        return 0;
+}
 
-        cqr->callback = dasd_wakeup_cb;
-        cqr->callback_data = (void *) &generic_waitq;
-        dasd_add_request_tail(cqr);
-        wait_event(generic_waitq, _wait_for_wakeup(cqr));
+static int __dasd_sleep_on_loop_condition(struct dasd_ccw_req *cqr)
+{
+        if (test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags)) {
+                if (cqr->refers) /* erp is not done yet */
+                        return 1;
+                return ((cqr->status != DASD_CQR_DONE) &&
+                        (cqr->status != DASD_CQR_FAILED));
+        } else
+                return (cqr->status == DASD_CQR_FILLED);
+}
 
-        if (cqr->status == DASD_CQR_DONE)
+static int _dasd_sleep_on(struct dasd_ccw_req *maincqr, int interruptible)
+{
+        struct dasd_device *device;
+        int rc;
+        struct list_head ccw_queue;
+        struct dasd_ccw_req *cqr;
+
+        INIT_LIST_HEAD(&ccw_queue);
+        maincqr->status = DASD_CQR_FILLED;
+        device = maincqr->startdev;
+        list_add(&maincqr->blocklist, &ccw_queue);
+        for (cqr = maincqr;  __dasd_sleep_on_loop_condition(cqr);
+             cqr = list_first_entry(&ccw_queue,
+                                    struct dasd_ccw_req, blocklist)) {
+
+                if (__dasd_sleep_on_erp(cqr))
+                        continue;
+                if (cqr->status != DASD_CQR_FILLED) /* could be failed */
+                        continue;
+
+                /* 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;
+                        continue;
+                }
+
+                /* Don't try to start requests if device is stopped */
+                if (interruptible) {
+                        rc = wait_event_interruptible(
+                                generic_waitq, !(device->stopped));
+                        if (rc == -ERESTARTSYS) {
+                                cqr->status = DASD_CQR_FAILED;
+                                maincqr->intrc = rc;
+                                continue;
+                        }
+                } else
+                        wait_event(generic_waitq, !(device->stopped));
+
+                cqr->callback = dasd_wakeup_cb;
+                cqr->callback_data = (void *) &generic_waitq;
+                dasd_add_request_tail(cqr);
+                if (interruptible) {
+                        rc = wait_event_interruptible(
+                                generic_waitq, _wait_for_wakeup(cqr));
+                        if (rc == -ERESTARTSYS) {
+                                dasd_cancel_req(cqr);
+                                /* wait (non-interruptible) for final status */
+                                wait_event(generic_waitq,
+                                           _wait_for_wakeup(cqr));
+                                cqr->status = DASD_CQR_FAILED;
+                                maincqr->intrc = rc;
+                                continue;
+                        }
+                } else
+                        wait_event(generic_waitq, _wait_for_wakeup(cqr));
+        }
+
+        maincqr->endclk = get_clock();
+        if ((maincqr->status != DASD_CQR_DONE) &&
+            (maincqr->intrc != -ERESTARTSYS))
+                dasd_log_sense(maincqr, &maincqr->irb);
+        if (maincqr->status == DASD_CQR_DONE)
                 rc = 0;
-        else if (cqr->intrc)
-                rc = cqr->intrc;
+        else if (maincqr->intrc)
+                rc = maincqr->intrc;
         else
                 rc = -EIO;
         return rc;
 }
 
 /*
+ * Queue a request to the tail of the device ccw_queue and wait for
+ * it's completion.
+ */
+int dasd_sleep_on(struct dasd_ccw_req *cqr)
+{
+        return _dasd_sleep_on(cqr, 0);
+}
+
+/*
  * Queue a request to the tail of the device ccw_queue and wait
  * interruptible for it's completion.
  */
 int dasd_sleep_on_interruptible(struct dasd_ccw_req *cqr)
 {
-        struct dasd_device *device;
-        int rc;
-
-        device = cqr->startdev;
-        cqr->callback = dasd_wakeup_cb;
-        cqr->callback_data = (void *) &generic_waitq;
-        dasd_add_request_tail(cqr);
-        rc = wait_event_interruptible(generic_waitq, _wait_for_wakeup(cqr));
-        if (rc == -ERESTARTSYS) {
-                dasd_cancel_req(cqr);
-                /* wait (non-interruptible) for final status */
-                wait_event(generic_waitq, _wait_for_wakeup(cqr));
-                cqr->intrc = rc;
-        }
-
-        if (cqr->status == DASD_CQR_DONE)
-                rc = 0;
-        else if (cqr->intrc)
-                rc = cqr->intrc;
-        else
-                rc = -EIO;
-        return rc;
+        return _dasd_sleep_on(cqr, 1);
 }
 
 /*
@@ -1629,7 +1721,7 @@ static void dasd_block_timeout(unsigned long ptr)
         block = (struct dasd_block *) ptr;
         spin_lock_irqsave(get_ccwdev_lock(block->base->cdev), flags);
         /* re-activate request queue */
-        block->base->stopped &= ~DASD_STOPPED_PENDING;
+        dasd_device_remove_stop_bits(block->base, DASD_STOPPED_PENDING);
         spin_unlock_irqrestore(get_ccwdev_lock(block->base->cdev), flags);
         dasd_schedule_block_bh(block);
 }
@@ -1656,11 +1748,10 @@ void dasd_block_clear_timer(struct dasd_block *block)
 /*
  * Process finished error recovery ccw.
  */
-static inline void __dasd_block_process_erp(struct dasd_block *block,
-                                            struct dasd_ccw_req *cqr)
+static void __dasd_process_erp(struct dasd_device *device,
+                               struct dasd_ccw_req *cqr)
 {
         dasd_erp_fn_t erp_fn;
-        struct dasd_device *device = block->base;
 
         if (cqr->status == DASD_CQR_DONE)
                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s", "ERP successful");
@@ -1724,9 +1815,12 @@ static void __dasd_process_request_queue(struct dasd_block *block)
                                  */
                                 if (!list_empty(&block->ccw_queue))
                                         break;
-                                spin_lock_irqsave(get_ccwdev_lock(basedev->cdev), flags);
-                                basedev->stopped |= DASD_STOPPED_PENDING;
-                                spin_unlock_irqrestore(get_ccwdev_lock(basedev->cdev), flags);
+                                spin_lock_irqsave(
+                                        get_ccwdev_lock(basedev->cdev), flags);
+                                dasd_device_set_stop_bits(basedev,
+                                                          DASD_STOPPED_PENDING);
+                                spin_unlock_irqrestore(
+                                        get_ccwdev_lock(basedev->cdev), flags);
                                 dasd_block_set_timer(block, HZ/2);
                                 break;
                         }
@@ -1812,7 +1906,7 @@ restart:
                         cqr->status = DASD_CQR_FILLED;
                         cqr->retries = 255;
                         spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
-                        base->stopped |= DASD_STOPPED_QUIESCE;
+                        dasd_device_set_stop_bits(base, DASD_STOPPED_QUIESCE);
                         spin_unlock_irqrestore(get_ccwdev_lock(base->cdev),
                                                flags);
                         goto restart;
@@ -1820,7 +1914,7 @@ restart:
 
                 /* Process finished ERP request. */
                 if (cqr->refers) {
-                        __dasd_block_process_erp(block, cqr);
+                        __dasd_process_erp(base, cqr);
                         goto restart;
                 }
 
@@ -1951,7 +2045,7 @@ restart_cb:
                 /* Process finished ERP request. */
                 if (cqr->refers) {
                         spin_lock_bh(&block->queue_lock);
-                        __dasd_block_process_erp(block, cqr);
+                        __dasd_process_erp(block->base, cqr);
                         spin_unlock_bh(&block->queue_lock);
                         /* restart list_for_xx loop since dasd_process_erp
                          * might remove multiple elements */
@@ -2410,16 +2504,16 @@ int dasd_generic_notify(struct ccw_device *cdev, int event)
                                 cqr->status = DASD_CQR_QUEUED;
                                 cqr->retries++;
                         }
-                device->stopped |= DASD_STOPPED_DC_WAIT;
+                dasd_device_set_stop_bits(device, DASD_STOPPED_DC_WAIT);
                 dasd_device_clear_timer(device);
                 dasd_schedule_device_bh(device);
                 ret = 1;
                 break;
         case CIO_OPER:
                 /* FIXME: add a sanity check. */
-                device->stopped &= ~DASD_STOPPED_DC_WAIT;
+                dasd_device_remove_stop_bits(device, DASD_STOPPED_DC_WAIT);
                 if (device->stopped & DASD_UNRESUMED_PM) {
-                        device->stopped &= ~DASD_UNRESUMED_PM;
+                        dasd_device_remove_stop_bits(device, DASD_UNRESUMED_PM);
                         dasd_restore_device(device);
                         ret = 1;
                         break;
@@ -2444,7 +2538,7 @@ int dasd_generic_pm_freeze(struct ccw_device *cdev)
         if (IS_ERR(device))
                 return PTR_ERR(device);
         /* disallow new I/O  */
-        device->stopped |= DASD_STOPPED_PM;
+        dasd_device_set_stop_bits(device, DASD_STOPPED_PM);
         /* clear active requests */
         INIT_LIST_HEAD(&freeze_queue);
         spin_lock_irq(get_ccwdev_lock(cdev));
@@ -2496,14 +2590,18 @@ int dasd_generic_restore_device(struct ccw_device *cdev)
                 return PTR_ERR(device);
 
         /* allow new IO again */
-        device->stopped &= ~DASD_STOPPED_PM;
-        device->stopped &= ~DASD_UNRESUMED_PM;
+        dasd_device_remove_stop_bits(device,
+                                     (DASD_STOPPED_PM | DASD_UNRESUMED_PM));
 
         dasd_schedule_device_bh(device);
 
-        if (device->discipline->restore)
+        /*
+         * call discipline restore function
+         * if device is stopped do nothing e.g. for disconnected devices
+         */
+        if (device->discipline->restore && !(device->stopped))
                 rc = device->discipline->restore(device);
-        if (rc)
+        if (rc || device->stopped)
                 /*
                  * if the resume failed for the DASD we put it in
                  * an UNRESUMED stop state
@@ -2553,8 +2651,7 @@ static struct dasd_ccw_req *dasd_generic_build_rdc(struct dasd_device *device,
         cqr->startdev = device;
         cqr->memdev = device;
         cqr->expires = 10*HZ;
-        clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
-        cqr->retries = 2;
+        cqr->retries = 256;
         cqr->buildclk = get_clock();
         cqr->status = DASD_CQR_FILLED;
         return cqr;