[S390] dasd: Improve handling of stolen DASD reservation

If a DASD device has been reserved by a Linux system, and later
this reservation is ‘stolen’ by a second system by means of an
unconditional reserve, then the first system receives a
notification about this fact. With this patch such an event can
be either ignored, as before, or it can be used to let the device
fail all I/O request, so that the device will not block anymore.

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

arch/s390/include/asm/dasd.h

@@ -80,6 +80,7 @@ typedef struct dasd_information2_t {
 #define DASD_FEATURE_INITIAL_ONLINE  0x04
 #define DASD_FEATURE_ERPLOG	     0x08
 #define DASD_FEATURE_FAILFAST	     0x10
+#define DASD_FEATURE_FAILONSLCK      0x20
 
 #define DASD_PARTN_BITS 2
 

drivers/s390/block/dasd.c

@@ -902,6 +902,16 @@ int dasd_start_IO(struct dasd_ccw_req *cqr)
 		return rc;
 	}
 	device = (struct dasd_device *) cqr->startdev;
+	if (((cqr->block &&
+	      test_bit(DASD_FLAG_LOCK_STOLEN, &cqr->block->base->flags)) ||
+	     test_bit(DASD_FLAG_LOCK_STOLEN, &device->flags)) &&
+	    !test_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags)) {
+		DBF_DEV_EVENT(DBF_DEBUG, device, "start_IO: return request %p "
+			      "because of stolen lock", cqr);
+		cqr->status = DASD_CQR_ERROR;
+		cqr->intrc = -EPERM;
+		return -EPERM;
+	}
 	if (cqr->retries < 0) {
 		/* internal error 14 - start_IO run out of retries */
 		sprintf(errorstring, "14 %p", cqr);
@@ -1115,16 +1125,11 @@ void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 	}
 
 	now = get_clock();
-
-	/* check for unsolicited interrupts */
 	cqr = (struct dasd_ccw_req *) intparm;
-	if (!cqr || ((scsw_cc(&irb->scsw) == 1) &&
-		     (scsw_fctl(&irb->scsw) & SCSW_FCTL_START_FUNC) &&
-		     ((scsw_stctl(&irb->scsw) == SCSW_STCTL_STATUS_PEND) ||
-		      (scsw_stctl(&irb->scsw) == (SCSW_STCTL_STATUS_PEND |
-						  SCSW_STCTL_ALERT_STATUS))))) {
-		if (cqr && cqr->status == DASD_CQR_IN_IO)
-			cqr->status = DASD_CQR_QUEUED;
+	/* check for conditions that should be handled immediately */
+	if (!cqr ||
+	    !(scsw_dstat(&irb->scsw) == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&
+	      scsw_cstat(&irb->scsw) == 0)) {
 		if (cqr)
 			memcpy(&cqr->irb, irb, sizeof(*irb));
 		device = dasd_device_from_cdev_locked(cdev);
@@ -1135,17 +1140,14 @@ void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 			dasd_put_device(device);
 			return;
 		}
-		device->discipline->dump_sense_dbf(device, irb,
-						   "unsolicited");
-		if ((device->features & DASD_FEATURE_ERPLOG))
-			device->discipline->dump_sense(device, cqr,
-						       irb);
-		dasd_device_clear_timer(device);
-		device->discipline->handle_unsolicited_interrupt(device,
-								 irb);
+		device->discipline->dump_sense_dbf(device, irb, "int");
+		if (device->features & DASD_FEATURE_ERPLOG)
+			device->discipline->dump_sense(device, cqr, irb);
+		device->discipline->check_for_device_change(device, cqr, irb);
 		dasd_put_device(device);
-		return;
 	}
+	if (!cqr)
+		return;
 
 	device = (struct dasd_device *) cqr->startdev;
 	if (!device ||
@@ -1185,13 +1187,6 @@ void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 					  struct dasd_ccw_req, devlist);
 		}
 	} else {  /* error */
-		memcpy(&cqr->irb, irb, sizeof(struct irb));
-		/* log sense for every failed I/O to s390 debugfeature */
-		dasd_log_sense_dbf(cqr, irb);
-		if (device->features & DASD_FEATURE_ERPLOG) {
-			dasd_log_sense(cqr, irb);
-		}
-
 		/*
 		 * If we don't want complex ERP for this request, then just
 		 * reset this and retry it in the fastpath
@@ -1232,13 +1227,13 @@ enum uc_todo dasd_generic_uc_handler(struct ccw_device *cdev, struct irb *irb)
 		goto out;
 	if (test_bit(DASD_FLAG_OFFLINE, &device->flags) ||
 	   device->state != device->target ||
-	   !device->discipline->handle_unsolicited_interrupt){
+	   !device->discipline->check_for_device_change){
 		dasd_put_device(device);
 		goto out;
 	}
-
-	dasd_device_clear_timer(device);
-	device->discipline->handle_unsolicited_interrupt(device, irb);
+	if (device->discipline->dump_sense_dbf)
+		device->discipline->dump_sense_dbf(device, irb, "uc");
+	device->discipline->check_for_device_change(device, NULL, irb);
 	dasd_put_device(device);
 out:
 	return UC_TODO_RETRY;
@@ -1659,15 +1654,19 @@ static int _dasd_sleep_on(struct dasd_ccw_req *maincqr, int interruptible)
 			continue;
 		if (cqr->status != DASD_CQR_FILLED) /* could be failed */
 			continue;
-
+		if (test_bit(DASD_FLAG_LOCK_STOLEN, &device->flags) &&
+		    !test_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags)) {
+			cqr->status = DASD_CQR_FAILED;
+			cqr->intrc = -EPERM;
+			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(
@@ -1752,13 +1751,18 @@ int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr)
 	int rc;
 
 	device = cqr->startdev;
+	if (test_bit(DASD_FLAG_LOCK_STOLEN, &device->flags) &&
+	    !test_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags)) {
+		cqr->status = DASD_CQR_FAILED;
+		cqr->intrc = -EPERM;
+		return -EIO;
+	}
 	spin_lock_irq(get_ccwdev_lock(device->cdev));
 	rc = _dasd_term_running_cqr(device);
 	if (rc) {
 		spin_unlock_irq(get_ccwdev_lock(device->cdev));
 		return rc;
 	}
-
 	cqr->callback = dasd_wakeup_cb;
 	cqr->callback_data = DASD_SLEEPON_START_TAG;
 	cqr->status = DASD_CQR_QUEUED;
@@ -2062,6 +2066,13 @@ static void __dasd_block_start_head(struct dasd_block *block)
 	list_for_each_entry(cqr, &block->ccw_queue, blocklist) {
 		if (cqr->status != DASD_CQR_FILLED)
 			continue;
+		if (test_bit(DASD_FLAG_LOCK_STOLEN, &block->base->flags) &&
+		    !test_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags)) {
+			cqr->status = DASD_CQR_FAILED;
+			cqr->intrc = -EPERM;
+			dasd_schedule_block_bh(block);
+			continue;
+		}
 		/* Non-temporary stop condition will trigger fail fast */
 		if (block->base->stopped & ~DASD_STOPPED_PENDING &&
 		    test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&

drivers/s390/block/dasd_devmap.c

@@ -1127,6 +1127,103 @@ dasd_expires_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(expires, 0644, dasd_expires_show, dasd_expires_store);
 
+static ssize_t dasd_reservation_policy_show(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	struct dasd_devmap *devmap;
+	int rc = 0;
+
+	devmap = dasd_find_busid(dev_name(dev));
+	if (IS_ERR(devmap)) {
+		rc = snprintf(buf, PAGE_SIZE, "ignore\n");
+	} else {
+		spin_lock(&dasd_devmap_lock);
+		if (devmap->features & DASD_FEATURE_FAILONSLCK)
+			rc = snprintf(buf, PAGE_SIZE, "fail\n");
+		else
+			rc = snprintf(buf, PAGE_SIZE, "ignore\n");
+		spin_unlock(&dasd_devmap_lock);
+	}
+	return rc;
+}
+
+static ssize_t dasd_reservation_policy_store(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t count)
+{
+	struct dasd_devmap *devmap;
+	int rc;
+
+	devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
+	if (IS_ERR(devmap))
+		return PTR_ERR(devmap);
+	rc = 0;
+	spin_lock(&dasd_devmap_lock);
+	if (sysfs_streq("ignore", buf))
+		devmap->features &= ~DASD_FEATURE_FAILONSLCK;
+	else if (sysfs_streq("fail", buf))
+		devmap->features |= DASD_FEATURE_FAILONSLCK;
+	else
+		rc = -EINVAL;
+	if (devmap->device)
+		devmap->device->features = devmap->features;
+	spin_unlock(&dasd_devmap_lock);
+	if (rc)
+		return rc;
+	else
+		return count;
+}
+
+static DEVICE_ATTR(reservation_policy, 0644,
+		   dasd_reservation_policy_show, dasd_reservation_policy_store);
+
+static ssize_t dasd_reservation_state_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct dasd_device *device;
+	int rc = 0;
+
+	device = dasd_device_from_cdev(to_ccwdev(dev));
+	if (IS_ERR(device))
+		return snprintf(buf, PAGE_SIZE, "none\n");
+
+	if (test_bit(DASD_FLAG_IS_RESERVED, &device->flags))
+		rc = snprintf(buf, PAGE_SIZE, "reserved\n");
+	else if (test_bit(DASD_FLAG_LOCK_STOLEN, &device->flags))
+		rc = snprintf(buf, PAGE_SIZE, "lost\n");
+	else
+		rc = snprintf(buf, PAGE_SIZE, "none\n");
+	dasd_put_device(device);
+	return rc;
+}
+
+static ssize_t dasd_reservation_state_store(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf, size_t count)
+{
+	struct dasd_device *device;
+	int rc = 0;
+
+	device = dasd_device_from_cdev(to_ccwdev(dev));
+	if (IS_ERR(device))
+		return -ENODEV;
+	if (sysfs_streq("reset", buf))
+		clear_bit(DASD_FLAG_LOCK_STOLEN, &device->flags);
+	else
+		rc = -EINVAL;
+	dasd_put_device(device);
+
+	if (rc)
+		return rc;
+	else
+		return count;
+}
+
+static DEVICE_ATTR(last_known_reservation_state, 0644,
+		   dasd_reservation_state_show, dasd_reservation_state_store);
+
 static struct attribute * dasd_attrs[] = {
 	&dev_attr_readonly.attr,
 	&dev_attr_discipline.attr,
@@ -1139,6 +1236,8 @@ static struct attribute * dasd_attrs[] = {
 	&dev_attr_erplog.attr,
 	&dev_attr_failfast.attr,
 	&dev_attr_expires.attr,
+	&dev_attr_reservation_policy.attr,
+	&dev_attr_last_known_reservation_state.attr,
 	NULL,
 };
 

drivers/s390/block/dasd_eckd.c

@@ -817,6 +817,7 @@ static int dasd_eckd_read_conf_immediately(struct dasd_device *device,
 
 	dasd_eckd_fill_rcd_cqr(device, cqr, rcd_buffer, lpm);
 	clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
+	set_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags);
 	cqr->retries = 5;
 	rc = dasd_sleep_on_immediatly(cqr);
 	return rc;
@@ -1947,9 +1948,9 @@ dasd_eckd_erp_postaction(struct dasd_ccw_req * cqr)
 	return dasd_default_erp_postaction;
 }
 
-
-static void dasd_eckd_handle_unsolicited_interrupt(struct dasd_device *device,
-						   struct irb *irb)
+static void dasd_eckd_check_for_device_change(struct dasd_device *device,
+					      struct dasd_ccw_req *cqr,
+					      struct irb *irb)
 {
 	char mask;
 	char *sense = NULL;
@@ -1973,40 +1974,41 @@ static void dasd_eckd_handle_unsolicited_interrupt(struct dasd_device *device,
 			/* schedule worker to reload device */
 			dasd_reload_device(device);
 		}
-
 		dasd_generic_handle_state_change(device);
 		return;
 	}
 
-	/* summary unit check */
 	sense = dasd_get_sense(irb);
-	if (sense && (sense[7] == 0x0D) &&
+	if (!sense)
+		return;
+
+	/* summary unit check */
+	if ((sense[7] == 0x0D) &&
 	    (scsw_dstat(&irb->scsw) & DEV_STAT_UNIT_CHECK)) {
 		dasd_alias_handle_summary_unit_check(device, irb);
 		return;
 	}
 
 	/* service information message SIM */
-	if (sense && !(sense[27] & DASD_SENSE_BIT_0) &&
+	if (!cqr && !(sense[27] & DASD_SENSE_BIT_0) &&
 	    ((sense[6] & DASD_SIM_SENSE) == DASD_SIM_SENSE)) {
 		dasd_3990_erp_handle_sim(device, sense);
-		dasd_schedule_device_bh(device);
 		return;
 	}
 
-	if ((scsw_cc(&irb->scsw) == 1) && !sense &&
-	    (scsw_fctl(&irb->scsw) == SCSW_FCTL_START_FUNC) &&
-	    (scsw_actl(&irb->scsw) == SCSW_ACTL_START_PEND) &&
-	    (scsw_stctl(&irb->scsw) == SCSW_STCTL_STATUS_PEND)) {
-		/* fake irb do nothing, they are handled elsewhere */
-		dasd_schedule_device_bh(device);
-		return;
+	/* loss of device reservation is handled via base devices only
+	 * as alias devices may be used with several bases
+	 */
+	if (device->block && (sense[7] == 0x3F) &&
+	    (scsw_dstat(&irb->scsw) & DEV_STAT_UNIT_CHECK) &&
+	    test_bit(DASD_FLAG_IS_RESERVED, &device->flags)) {
+		if (device->features & DASD_FEATURE_FAILONSLCK)
+			set_bit(DASD_FLAG_LOCK_STOLEN, &device->flags);
+		clear_bit(DASD_FLAG_IS_RESERVED, &device->flags);
+		dev_err(&device->cdev->dev,
+			"The device reservation was lost\n");
 	}
-
-	dasd_schedule_device_bh(device);
-	return;
-};
-
+}
 
 static struct dasd_ccw_req *dasd_eckd_build_cp_cmd_single(
 					       struct dasd_device *startdev,
@@ -2931,6 +2933,8 @@ dasd_eckd_release(struct dasd_device *device)
 	cqr->status = DASD_CQR_FILLED;
 
 	rc = dasd_sleep_on_immediatly(cqr);
+	if (!rc)
+		clear_bit(DASD_FLAG_IS_RESERVED, &device->flags);
 
 	if (useglobal)
 		mutex_unlock(&dasd_reserve_mutex);
@@ -2984,6 +2988,8 @@ dasd_eckd_reserve(struct dasd_device *device)
 	cqr->status = DASD_CQR_FILLED;
 
 	rc = dasd_sleep_on_immediatly(cqr);
+	if (!rc)
+		set_bit(DASD_FLAG_IS_RESERVED, &device->flags);
 
 	if (useglobal)
 		mutex_unlock(&dasd_reserve_mutex);
@@ -3036,6 +3042,8 @@ dasd_eckd_steal_lock(struct dasd_device *device)
 	cqr->status = DASD_CQR_FILLED;
 
 	rc = dasd_sleep_on_immediatly(cqr);
+	if (!rc)
+		set_bit(DASD_FLAG_IS_RESERVED, &device->flags);
 
 	if (useglobal)
 		mutex_unlock(&dasd_reserve_mutex);
@@ -3088,6 +3096,7 @@ static int dasd_eckd_snid(struct dasd_device *device,
 	cqr->memdev = device;
 	clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 	set_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags);
+	set_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags);
 	cqr->retries = 5;
 	cqr->expires = 10 * HZ;
 	cqr->buildclk = get_clock();
@@ -3832,7 +3841,7 @@ static struct dasd_discipline dasd_eckd_discipline = {
 	.format_device = dasd_eckd_format_device,
 	.erp_action = dasd_eckd_erp_action,
 	.erp_postaction = dasd_eckd_erp_postaction,
-	.handle_unsolicited_interrupt = dasd_eckd_handle_unsolicited_interrupt,
+	.check_for_device_change = dasd_eckd_check_for_device_change,
 	.build_cp = dasd_eckd_build_alias_cp,
 	.free_cp = dasd_eckd_free_alias_cp,
 	.dump_sense = dasd_eckd_dump_sense,