[S390] dasd: add hyper PAV support to DASD device driver, part 1

Parallel access volumes (PAV) is a storage server feature, that allows
to start multiple channel programs on the same DASD in parallel. It
defines alias devices which can be used as alternative paths to the
same disk. With the old base PAV support we only needed rudimentary
functionality in the DASD device driver. As the mapping between base
and alias devices was static, we just had to export an identifier
(uid) and could leave the combining of devices to external layers
like a device mapper multipath.
Now hyper PAV removes the requirement to dedicate alias devices to
specific base devices. Instead each alias devices can be combined with
multiple base device on a per request basis. This requires full
support by the DASD device driver as now each channel program itself
has to identify the target base device.
The changes to the dasd device driver and the ECKD discipline are:
- Separate subchannel device representation (dasd_device) from block
  device representation (dasd_block). Only base devices are block
  devices.
- Gather information about base and alias devices and possible
  combinations.
- For each request decide which dasd_device should be used (base or
  alias) and build specific channel program.
- Support summary unit checks, which allow the storage server to
  upgrade / downgrade between base and hyper PAV at runtime (support
  is mandatory).

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

1 files changed, 944 insertions, 736 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index da4fe1ecef9..db9193d3898 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -48,13 +48,15 @@ MODULE_LICENSE("GPL");
 /*
  * SECTION: prototypes for static functions of dasd.c
  */
-static int  dasd_alloc_queue(struct dasd_device * device);
-static void dasd_setup_queue(struct dasd_device * device);
-static void dasd_free_queue(struct dasd_device * device);
-static void dasd_flush_request_queue(struct dasd_device *);
-static int dasd_flush_ccw_queue(struct dasd_device *, int);
-static void dasd_tasklet(struct dasd_device *);
+static int  dasd_alloc_queue(struct dasd_block *);
+static void dasd_setup_queue(struct dasd_block *);
+static void dasd_free_queue(struct dasd_block *);
+static void dasd_flush_request_queue(struct dasd_block *);
+static int dasd_flush_block_queue(struct dasd_block *);
+static void dasd_device_tasklet(struct dasd_device *);
+static void dasd_block_tasklet(struct dasd_block *);
 static void do_kick_device(struct work_struct *);
+static void dasd_return_cqr_cb(struct dasd_ccw_req *, void *);
 
 /*
  * SECTION: Operations on the device structure.
@@ -65,26 +67,23 @@ static wait_queue_head_t dasd_flush_wq;
 /*
  * Allocate memory for a new device structure.
  */
-struct dasd_device *
-dasd_alloc_device(void)
+struct dasd_device *dasd_alloc_device(void)
 {
 	struct dasd_device *device;
 
-	device = kzalloc(sizeof (struct dasd_device), GFP_ATOMIC);
-	if (device == NULL)
+	device = kzalloc(sizeof(struct dasd_device), GFP_ATOMIC);
+	if (!device)
 		return ERR_PTR(-ENOMEM);
-	/* open_count = 0 means device online but not in use */
-	atomic_set(&device->open_count, -1);
 
 	/* Get two pages for normal block device operations. */
 	device->ccw_mem = (void *) __get_free_pages(GFP_ATOMIC | GFP_DMA, 1);
-	if (device->ccw_mem == NULL) {
+	if (!device->ccw_mem) {
 		kfree(device);
 		return ERR_PTR(-ENOMEM);
 	}
 	/* Get one page for error recovery. */
 	device->erp_mem = (void *) get_zeroed_page(GFP_ATOMIC | GFP_DMA);
-	if (device->erp_mem == NULL) {
+	if (!device->erp_mem) {
 		free_pages((unsigned long) device->ccw_mem, 1);
 		kfree(device);
 		return ERR_PTR(-ENOMEM);
@@ -93,10 +92,9 @@ dasd_alloc_device(void)
 	dasd_init_chunklist(&device->ccw_chunks, device->ccw_mem, PAGE_SIZE*2);
 	dasd_init_chunklist(&device->erp_chunks, device->erp_mem, PAGE_SIZE);
 	spin_lock_init(&device->mem_lock);
-	spin_lock_init(&device->request_queue_lock);
-	atomic_set (&device->tasklet_scheduled, 0);
+	atomic_set(&device->tasklet_scheduled, 0);
 	tasklet_init(&device->tasklet,
-		     (void (*)(unsigned long)) dasd_tasklet,
+		     (void (*)(unsigned long)) dasd_device_tasklet,
 		     (unsigned long) device);
 	INIT_LIST_HEAD(&device->ccw_queue);
 	init_timer(&device->timer);
@@ -110,8 +108,7 @@ dasd_alloc_device(void)
 /*
  * Free memory of a device structure.
  */
-void
-dasd_free_device(struct dasd_device *device)
+void dasd_free_device(struct dasd_device *device)
 {
 	kfree(device->private);
 	free_page((unsigned long) device->erp_mem);
@@ -120,10 +117,42 @@ dasd_free_device(struct dasd_device *device)
 }
 
 /*
+ * Allocate memory for a new device structure.
+ */
+struct dasd_block *dasd_alloc_block(void)
+{
+	struct dasd_block *block;
+
+	block = kzalloc(sizeof(*block), GFP_ATOMIC);
+	if (!block)
+		return ERR_PTR(-ENOMEM);
+	/* open_count = 0 means device online but not in use */
+	atomic_set(&block->open_count, -1);
+
+	spin_lock_init(&block->request_queue_lock);
+	atomic_set(&block->tasklet_scheduled, 0);
+	tasklet_init(&block->tasklet,
+		     (void (*)(unsigned long)) dasd_block_tasklet,
+		     (unsigned long) block);
+	INIT_LIST_HEAD(&block->ccw_queue);
+	spin_lock_init(&block->queue_lock);
+	init_timer(&block->timer);
+
+	return block;
+}
+
+/*
+ * Free memory of a device structure.
+ */
+void dasd_free_block(struct dasd_block *block)
+{
+	kfree(block);
+}
+
+/*
  * Make a new device known to the system.
  */
-static int
-dasd_state_new_to_known(struct dasd_device *device)
+static int dasd_state_new_to_known(struct dasd_device *device)
 {
 	int rc;
 
@@ -133,12 +162,13 @@ dasd_state_new_to_known(struct dasd_device *device)
 	 */
 	dasd_get_device(device);
 
-	rc = dasd_alloc_queue(device);
-	if (rc) {
-		dasd_put_device(device);
-		return rc;
+	if (device->block) {
+		rc = dasd_alloc_queue(device->block);
+		if (rc) {
+			dasd_put_device(device);
+			return rc;
+		}
 	}
-
 	device->state = DASD_STATE_KNOWN;
 	return 0;
 }
@@ -146,21 +176,24 @@ dasd_state_new_to_known(struct dasd_device *device)
 /*
  * Let the system forget about a device.
  */
-static int
-dasd_state_known_to_new(struct dasd_device * device)
+static int dasd_state_known_to_new(struct dasd_device *device)
 {
 	/* Disable extended error reporting for this device. */
 	dasd_eer_disable(device);
 	/* Forget the discipline information. */
-	if (device->discipline)
+	if (device->discipline) {
+		if (device->discipline->uncheck_device)
+			device->discipline->uncheck_device(device);
 		module_put(device->discipline->owner);
+	}
 	device->discipline = NULL;
 	if (device->base_discipline)
 		module_put(device->base_discipline->owner);
 	device->base_discipline = NULL;
 	device->state = DASD_STATE_NEW;
 
-	dasd_free_queue(device);
+	if (device->block)
+		dasd_free_queue(device->block);
 
 	/* Give up reference we took in dasd_state_new_to_known. */
 	dasd_put_device(device);
@@ -170,19 +203,19 @@ dasd_state_known_to_new(struct dasd_device * device)
 /*
  * Request the irq line for the device.
  */
-static int
-dasd_state_known_to_basic(struct dasd_device * device)
+static int dasd_state_known_to_basic(struct dasd_device *device)
 {
 	int rc;
 
 	/* Allocate and register gendisk structure. */
-	rc = dasd_gendisk_alloc(device);
-	if (rc)
-		return rc;
-
+	if (device->block) {
+		rc = dasd_gendisk_alloc(device->block);
+		if (rc)
+			return rc;
+	}
 	/* register 'device' debug area, used for all DBF_DEV_XXX calls */
 	device->debug_area = debug_register(device->cdev->dev.bus_id, 1, 2,
-					    8 * sizeof (long));
+					    8 * sizeof(long));
 	debug_register_view(device->debug_area, &debug_sprintf_view);
 	debug_set_level(device->debug_area, DBF_WARNING);
 	DBF_DEV_EVENT(DBF_EMERG, device, "%s", "debug area created");
@@ -194,16 +227,17 @@ dasd_state_known_to_basic(struct dasd_device * device)
 /*
  * Release the irq line for the device. Terminate any running i/o.
  */
-static int
-dasd_state_basic_to_known(struct dasd_device * device)
+static int dasd_state_basic_to_known(struct dasd_device *device)
 {
 	int rc;
-
-	dasd_gendisk_free(device);
-	rc = dasd_flush_ccw_queue(device, 1);
+	if (device->block) {
+		dasd_gendisk_free(device->block);
+		dasd_block_clear_timer(device->block);
+	}
+	rc = dasd_flush_device_queue(device);
 	if (rc)
 		return rc;
-	dasd_clear_timer(device);
+	dasd_device_clear_timer(device);
 
 	DBF_DEV_EVENT(DBF_EMERG, device, "%p debug area deleted", device);
 	if (device->debug_area != NULL) {
@@ -228,26 +262,32 @@ dasd_state_basic_to_known(struct dasd_device * device)
  * In case the analysis returns an error, the device setup is stopped
  * (a fake disk was already added to allow formatting).
  */
-static int
-dasd_state_basic_to_ready(struct dasd_device * device)
+static int dasd_state_basic_to_ready(struct dasd_device *device)
 {
 	int rc;
+	struct dasd_block *block;
 
 	rc = 0;
-	if (device->discipline->do_analysis != NULL)
-		rc = device->discipline->do_analysis(device);
-	if (rc) {
-		if (rc != -EAGAIN)
-			device->state = DASD_STATE_UNFMT;
-		return rc;
-	}
+	block = device->block;
 	/* make disk known with correct capacity */
-	dasd_setup_queue(device);
-	set_capacity(device->gdp, device->blocks << device->s2b_shift);
-	device->state = DASD_STATE_READY;
-	rc = dasd_scan_partitions(device);
-	if (rc)
-		device->state = DASD_STATE_BASIC;
+	if (block) {
+		if (block->base->discipline->do_analysis != NULL)
+			rc = block->base->discipline->do_analysis(block);
+		if (rc) {
+			if (rc != -EAGAIN)
+				device->state = DASD_STATE_UNFMT;
+			return rc;
+		}
+		dasd_setup_queue(block);
+		set_capacity(block->gdp,
+			     block->blocks << block->s2b_shift);
+		device->state = DASD_STATE_READY;
+		rc = dasd_scan_partitions(block);
+		if (rc)
+			device->state = DASD_STATE_BASIC;
+	} else {
+		device->state = DASD_STATE_READY;
+	}
 	return rc;
 }
 
@@ -256,28 +296,31 @@ dasd_state_basic_to_ready(struct dasd_device * device)
  * Forget format information. Check if the target level is basic
  * and if it is create fake disk for formatting.
  */
-static int
-dasd_state_ready_to_basic(struct dasd_device * device)
+static int dasd_state_ready_to_basic(struct dasd_device *device)
 {
 	int rc;
 
-	rc = dasd_flush_ccw_queue(device, 0);
-	if (rc)
-		return rc;
-	dasd_destroy_partitions(device);
-	dasd_flush_request_queue(device);
-	device->blocks = 0;
-	device->bp_block = 0;
-	device->s2b_shift = 0;
 	device->state = DASD_STATE_BASIC;
+	if (device->block) {
+		struct dasd_block *block = device->block;
+		rc = dasd_flush_block_queue(block);
+		if (rc) {
+			device->state = DASD_STATE_READY;
+			return rc;
+		}
+		dasd_destroy_partitions(block);
+		dasd_flush_request_queue(block);
+		block->blocks = 0;
+		block->bp_block = 0;
+		block->s2b_shift = 0;
+	}
 	return 0;
 }
 
 /*
  * Back to basic.
  */
-static int
-dasd_state_unfmt_to_basic(struct dasd_device * device)
+static int dasd_state_unfmt_to_basic(struct dasd_device *device)
 {
 	device->state = DASD_STATE_BASIC;
 	return 0;
@@ -291,17 +334,31 @@ dasd_state_unfmt_to_basic(struct dasd_device * device)
 static int
 dasd_state_ready_to_online(struct dasd_device * device)
 {
+	int rc;
+
+	if (device->discipline->ready_to_online) {
+		rc = device->discipline->ready_to_online(device);
+		if (rc)
+			return rc;
+	}
 	device->state = DASD_STATE_ONLINE;
-	dasd_schedule_bh(device);
+	if (device->block)
+		dasd_schedule_block_bh(device->block);
 	return 0;
 }
 
 /*
  * Stop the requeueing of requests again.
  */
-static int
-dasd_state_online_to_ready(struct dasd_device * device)
+static int dasd_state_online_to_ready(struct dasd_device *device)
 {
+	int rc;
+
+	if (device->discipline->online_to_ready) {
+		rc = device->discipline->online_to_ready(device);
+		if (rc)
+			return rc;
+	}
 	device->state = DASD_STATE_READY;
 	return 0;
 }
@@ -309,8 +366,7 @@ dasd_state_online_to_ready(struct dasd_device * device)
 /*
  * Device startup state changes.
  */
-static int
-dasd_increase_state(struct dasd_device *device)
+static int dasd_increase_state(struct dasd_device *device)
 {
 	int rc;
 
@@ -345,8 +401,7 @@ dasd_increase_state(struct dasd_device *device)
 /*
  * Device shutdown state changes.
  */
-static int
-dasd_decrease_state(struct dasd_device *device)
+static int dasd_decrease_state(struct dasd_device *device)
 {
 	int rc;
 
@@ -381,8 +436,7 @@ dasd_decrease_state(struct dasd_device *device)
 /*
  * This is the main startup/shutdown routine.
  */
-static void
-dasd_change_state(struct dasd_device *device)
+static void dasd_change_state(struct dasd_device *device)
 {
         int rc;
 
@@ -409,17 +463,15 @@ dasd_change_state(struct dasd_device *device)
  * dasd_kick_device will schedule a call do do_kick_device to the kernel
  * event daemon.
  */
-static void
-do_kick_device(struct work_struct *work)
+static void do_kick_device(struct work_struct *work)
 {
 	struct dasd_device *device = container_of(work, struct dasd_device, kick_work);
 	dasd_change_state(device);
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
 	dasd_put_device(device);
 }
 
-void
-dasd_kick_device(struct dasd_device *device)
+void dasd_kick_device(struct dasd_device *device)
 {
 	dasd_get_device(device);
 	/* queue call to dasd_kick_device to the kernel event daemon. */
@@ -429,8 +481,7 @@ dasd_kick_device(struct dasd_device *device)
 /*
  * Set the target state for a device and starts the state change.
  */
-void
-dasd_set_target_state(struct dasd_device *device, int target)
+void dasd_set_target_state(struct dasd_device *device, int target)
 {
 	/* If we are in probeonly mode stop at DASD_STATE_READY. */
 	if (dasd_probeonly && target > DASD_STATE_READY)
@@ -447,14 +498,12 @@ dasd_set_target_state(struct dasd_device *device, int target)
 /*
  * Enable devices with device numbers in [from..to].
  */
-static inline int
-_wait_for_device(struct dasd_device *device)
+static inline int _wait_for_device(struct dasd_device *device)
 {
 	return (device->state == device->target);
 }
 
-void
-dasd_enable_device(struct dasd_device *device)
+void dasd_enable_device(struct dasd_device *device)
 {
 	dasd_set_target_state(device, DASD_STATE_ONLINE);
 	if (device->state <= DASD_STATE_KNOWN)
@@ -475,20 +524,20 @@ unsigned int dasd_profile_level = DASD_PROFILE_OFF;
 /*
  * Increments counter in global and local profiling structures.
  */
-#define dasd_profile_counter(value, counter, device) \
+#define dasd_profile_counter(value, counter, block) \
 { \
 	int index; \
 	for (index = 0; index < 31 && value >> (2+index); index++); \
 	dasd_global_profile.counter[index]++; \
-	device->profile.counter[index]++; \
+	block->profile.counter[index]++; \
 }
 
 /*
  * Add profiling information for cqr before execution.
  */
-static void
-dasd_profile_start(struct dasd_device *device, struct dasd_ccw_req * cqr,
-		   struct request *req)
+static void dasd_profile_start(struct dasd_block *block,
+			       struct dasd_ccw_req *cqr,
+			       struct request *req)
 {
 	struct list_head *l;
 	unsigned int counter;
@@ -498,19 +547,19 @@ dasd_profile_start(struct dasd_device *device, struct dasd_ccw_req * cqr,
 
 	/* count the length of the chanq for statistics */
 	counter = 0;
-	list_for_each(l, &device->ccw_queue)
+	list_for_each(l, &block->ccw_queue)
 		if (++counter >= 31)
 			break;
 	dasd_global_profile.dasd_io_nr_req[counter]++;
-	device->profile.dasd_io_nr_req[counter]++;
+	block->profile.dasd_io_nr_req[counter]++;
 }
 
 /*
  * Add profiling information for cqr after execution.
  */
-static void
-dasd_profile_end(struct dasd_device *device, struct dasd_ccw_req * cqr,
-		 struct request *req)
+static void dasd_profile_end(struct dasd_block *block,
+			     struct dasd_ccw_req *cqr,
+			     struct request *req)
 {
 	long strtime, irqtime, endtime, tottime;	/* in microseconds */
 	long tottimeps, sectors;
@@ -532,27 +581,27 @@ dasd_profile_end(struct dasd_device *device, struct dasd_ccw_req * cqr,
 
 	if (!dasd_global_profile.dasd_io_reqs)
 		memset(&dasd_global_profile, 0,
-		       sizeof (struct dasd_profile_info_t));
+		       sizeof(struct dasd_profile_info_t));
 	dasd_global_profile.dasd_io_reqs++;
 	dasd_global_profile.dasd_io_sects += sectors;
 
-	if (!device->profile.dasd_io_reqs)
-		memset(&device->profile, 0,
-		       sizeof (struct dasd_profile_info_t));
-	device->profile.dasd_io_reqs++;
-	device->profile.dasd_io_sects += sectors;
+	if (!block->profile.dasd_io_reqs)
+		memset(&block->profile, 0,
+		       sizeof(struct dasd_profile_info_t));
+	block->profile.dasd_io_reqs++;
+	block->profile.dasd_io_sects += sectors;
 
-	dasd_profile_counter(sectors, dasd_io_secs, device);
-	dasd_profile_counter(tottime, dasd_io_times, device);
-	dasd_profile_counter(tottimeps, dasd_io_timps, device);
-	dasd_profile_counter(strtime, dasd_io_time1, device);
-	dasd_profile_counter(irqtime, dasd_io_time2, device);
-	dasd_profile_counter(irqtime / sectors, dasd_io_time2ps, device);
-	dasd_profile_counter(endtime, dasd_io_time3, device);
+	dasd_profile_counter(sectors, dasd_io_secs, block);
+	dasd_profile_counter(tottime, dasd_io_times, block);
+	dasd_profile_counter(tottimeps, dasd_io_timps, block);
+	dasd_profile_counter(strtime, dasd_io_time1, block);
+	dasd_profile_counter(irqtime, dasd_io_time2, block);
+	dasd_profile_counter(irqtime / sectors, dasd_io_time2ps, block);
+	dasd_profile_counter(endtime, dasd_io_time3, block);
 }
 #else
-#define dasd_profile_start(device, cqr, req) do {} while (0)
-#define dasd_profile_end(device, cqr, req) do {} while (0)
+#define dasd_profile_start(block, cqr, req) do {} while (0)
+#define dasd_profile_end(block, cqr, req) do {} while (0)
 #endif				/* CONFIG_DASD_PROFILE */
 
 /*
@@ -562,9 +611,9 @@ dasd_profile_end(struct dasd_device *device, struct dasd_ccw_req * cqr,
  * memory and 2) dasd_smalloc_request uses the static ccw memory
  * that gets allocated for each device.
  */
-struct dasd_ccw_req *
-dasd_kmalloc_request(char *magic, int cplength, int datasize,
-		   struct dasd_device * device)
+struct dasd_ccw_req *dasd_kmalloc_request(char *magic, int cplength,
+					  int datasize,
+					  struct dasd_device *device)
 {
 	struct dasd_ccw_req *cqr;
 
@@ -600,9 +649,9 @@ dasd_kmalloc_request(char *magic, int cplength, int datasize,
 	return cqr;
 }
 
-struct dasd_ccw_req *
-dasd_smalloc_request(char *magic, int cplength, int datasize,
-		   struct dasd_device * device)
+struct dasd_ccw_req *dasd_smalloc_request(char *magic, int cplength,
+					  int datasize,
+					  struct dasd_device *device)
 {
 	unsigned long flags;
 	struct dasd_ccw_req *cqr;
@@ -649,8 +698,7 @@ dasd_smalloc_request(char *magic, int cplength, int datasize,
  * idal lists that might have been created by dasd_set_cda and the
  * struct dasd_ccw_req itself.
  */
-void
-dasd_kfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
+void dasd_kfree_request(struct dasd_ccw_req *cqr, struct dasd_device *device)
 {
 #ifdef CONFIG_64BIT
 	struct ccw1 *ccw;
@@ -667,8 +715,7 @@ dasd_kfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
 	dasd_put_device(device);
 }
 
-void
-dasd_sfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
+void dasd_sfree_request(struct dasd_ccw_req *cqr, struct dasd_device *device)
 {
 	unsigned long flags;
 
@@ -681,14 +728,13 @@ dasd_sfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
 /*
  * Check discipline magic in cqr.
  */
-static inline int
-dasd_check_cqr(struct dasd_ccw_req *cqr)
+static inline int dasd_check_cqr(struct dasd_ccw_req *cqr)
 {
 	struct dasd_device *device;
 
 	if (cqr == NULL)
 		return -EINVAL;
-	device = cqr->device;
+	device = cqr->startdev;
 	if (strncmp((char *) &cqr->magic, device->discipline->ebcname, 4)) {
 		DEV_MESSAGE(KERN_WARNING, device,
 			    " dasd_ccw_req 0x%08x magic doesn't match"
@@ -706,8 +752,7 @@ dasd_check_cqr(struct dasd_ccw_req *cqr)
  * ccw_device_clear can fail if the i/o subsystem
  * is in a bad mood.
  */
-int
-dasd_term_IO(struct dasd_ccw_req * cqr)
+int dasd_term_IO(struct dasd_ccw_req *cqr)
 {
 	struct dasd_device *device;
 	int retries, rc;
@@ -717,13 +762,13 @@ dasd_term_IO(struct dasd_ccw_req * cqr)
 	if (rc)
 		return rc;
 	retries = 0;
-	device = (struct dasd_device *) cqr->device;
+	device = (struct dasd_device *) cqr->startdev;
 	while ((retries < 5) && (cqr->status == DASD_CQR_IN_IO)) {
 		rc = ccw_device_clear(device->cdev, (long) cqr);
 		switch (rc) {
 		case 0:	/* termination successful */
 			cqr->retries--;
-			cqr->status = DASD_CQR_CLEAR;
+			cqr->status = DASD_CQR_CLEAR_PENDING;
 			cqr->stopclk = get_clock();
 			cqr->starttime = 0;
 			DBF_DEV_EVENT(DBF_DEBUG, device,
@@ -753,7 +798,7 @@ dasd_term_IO(struct dasd_ccw_req * cqr)
 		}
 		retries++;
 	}
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
 	return rc;
 }
 
@@ -761,8 +806,7 @@ dasd_term_IO(struct dasd_ccw_req * cqr)
  * Start the i/o. This start_IO can fail if the channel is really busy.
  * In that case set up a timer to start the request later.
  */
-int
-dasd_start_IO(struct dasd_ccw_req * cqr)
+int dasd_start_IO(struct dasd_ccw_req *cqr)
 {
 	struct dasd_device *device;
 	int rc;
@@ -771,12 +815,12 @@ dasd_start_IO(struct dasd_ccw_req * cqr)
 	rc = dasd_check_cqr(cqr);
 	if (rc)
 		return rc;
-	device = (struct dasd_device *) cqr->device;
+	device = (struct dasd_device *) cqr->startdev;
 	if (cqr->retries < 0) {
 		DEV_MESSAGE(KERN_DEBUG, device,
 			    "start_IO: request %p (%02x/%i) - no retry left.",
 			    cqr, cqr->status, cqr->retries);
-		cqr->status = DASD_CQR_FAILED;
+		cqr->status = DASD_CQR_ERROR;
 		return -EIO;
 	}
 	cqr->startclk = get_clock();
@@ -833,8 +877,7 @@ dasd_start_IO(struct dasd_ccw_req * cqr)
  * The head of the ccw queue will have status DASD_CQR_IN_IO for 1),
  * DASD_CQR_QUEUED for 2) and 3).
  */
-static void
-dasd_timeout_device(unsigned long ptr)
+static void dasd_device_timeout(unsigned long ptr)
 {
 	unsigned long flags;
 	struct dasd_device *device;
@@ -844,14 +887,13 @@ dasd_timeout_device(unsigned long ptr)
 	/* re-activate request queue */
         device->stopped &= ~DASD_STOPPED_PENDING;
 	spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
 }
 
 /*
  * Setup timeout for a device in jiffies.
  */
-void
-dasd_set_timer(struct dasd_device *device, int expires)
+void dasd_device_set_timer(struct dasd_device *device, int expires)
 {
 	if (expires == 0) {
 		if (timer_pending(&device->timer))
@@ -862,7 +904,7 @@ dasd_set_timer(struct dasd_device *device, int expires)
 		if (mod_timer(&device->timer, jiffies + expires))
 			return;
 	}
-	device->timer.function = dasd_timeout_device;
+	device->timer.function = dasd_device_timeout;
 	device->timer.data = (unsigned long) device;
 	device->timer.expires = jiffies + expires;
 	add_timer(&device->timer);
@@ -871,15 +913,14 @@ dasd_set_timer(struct dasd_device *device, int expires)
 /*
  * Clear timeout for a device.
  */
-void
-dasd_clear_timer(struct dasd_device *device)
+void dasd_device_clear_timer(struct dasd_device *device)
 {
 	if (timer_pending(&device->timer))
 		del_timer(&device->timer);
 }
 
-static void
-dasd_handle_killed_request(struct ccw_device *cdev, unsigned long intparm)
+static void dasd_handle_killed_request(struct ccw_device *cdev,
+				       unsigned long intparm)
 {
 	struct dasd_ccw_req *cqr;
 	struct dasd_device *device;
@@ -893,7 +934,7 @@ dasd_handle_killed_request(struct ccw_device *cdev, unsigned long intparm)
 		return;
 	}
 
-	device = (struct dasd_device *) cqr->device;
+	device = (struct dasd_device *) cqr->startdev;
 	if (device == NULL ||
 	    device != dasd_device_from_cdev_locked(cdev) ||
 	    strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
@@ -905,46 +946,32 @@ dasd_handle_killed_request(struct ccw_device *cdev, unsigned long intparm)
 	/* Schedule request to be retried. */
 	cqr->status = DASD_CQR_QUEUED;
 
-	dasd_clear_timer(device);
-	dasd_schedule_bh(device);
+	dasd_device_clear_timer(device);
+	dasd_schedule_device_bh(device);
 	dasd_put_device(device);
 }
 
-static void
-dasd_handle_state_change_pending(struct dasd_device *device)
+void dasd_generic_handle_state_change(struct dasd_device *device)
 {
-	struct dasd_ccw_req *cqr;
-	struct list_head *l, *n;
-
 	/* First of all start sense subsystem status request. */
 	dasd_eer_snss(device);
 
 	device->stopped &= ~DASD_STOPPED_PENDING;
-
-        /* restart all 'running' IO on queue */
-	list_for_each_safe(l, n, &device->ccw_queue) {
-		cqr = list_entry(l, struct dasd_ccw_req, list);
-                if (cqr->status == DASD_CQR_IN_IO) {
-                        cqr->status = DASD_CQR_QUEUED;
-		}
-        }
-	dasd_clear_timer(device);
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
+	if (device->block)
+		dasd_schedule_block_bh(device->block);
 }
 
 /*
  * Interrupt handler for "normal" ssch-io based dasd devices.
  */
-void
-dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
-		 struct irb *irb)
+void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
+		      struct irb *irb)
 {
 	struct dasd_ccw_req *cqr, *next;
 	struct dasd_device *device;
 	unsigned long long now;
 	int expires;
-	dasd_era_t era;
-	char mask;
 
 	if (IS_ERR(irb)) {
 		switch (PTR_ERR(irb)) {
@@ -969,29 +996,25 @@ dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 		  cdev->dev.bus_id, ((irb->scsw.cstat<<8)|irb->scsw.dstat),
 		  (unsigned int) intparm);
 
-	/* first of all check for state change pending interrupt */
-	mask = DEV_STAT_ATTENTION | DEV_STAT_DEV_END | DEV_STAT_UNIT_EXCEP;
-	if ((irb->scsw.dstat & mask) == mask) {
+	/* check for unsolicited interrupts */
+	cqr = (struct dasd_ccw_req *) intparm;
+	if (!cqr || ((irb->scsw.cc == 1) &&
+		     (irb->scsw.fctl & SCSW_FCTL_START_FUNC) &&
+		     (irb->scsw.stctl & SCSW_STCTL_STATUS_PEND)) ) {
+		if (cqr && cqr->status == DASD_CQR_IN_IO)
+			cqr->status = DASD_CQR_QUEUED;
 		device = dasd_device_from_cdev_locked(cdev);
 		if (!IS_ERR(device)) {
-			dasd_handle_state_change_pending(device);
+			dasd_device_clear_timer(device);
+			device->discipline->handle_unsolicited_interrupt(device,
+									 irb);
 			dasd_put_device(device);
 		}
 		return;
 	}
 
-	cqr = (struct dasd_ccw_req *) intparm;
-
-	/* check for unsolicited interrupts */
-	if (cqr == NULL) {
-		MESSAGE(KERN_DEBUG,
-			"unsolicited interrupt received: bus_id %s",
-			cdev->dev.bus_id);
-		return;
-	}
-
-	device = (struct dasd_device *) cqr->device;
-	if (device == NULL ||
+	device = (struct dasd_device *) cqr->startdev;
+	if (!device ||
 	    strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
 		MESSAGE(KERN_DEBUG, "invalid device in request: bus_id %s",
 			cdev->dev.bus_id);
@@ -999,12 +1022,12 @@ dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 	}
 
 	/* Check for clear pending */
-	if (cqr->status == DASD_CQR_CLEAR &&
+	if (cqr->status == DASD_CQR_CLEAR_PENDING &&
 	    irb->scsw.fctl & SCSW_FCTL_CLEAR_FUNC) {
-		cqr->status = DASD_CQR_QUEUED;
-		dasd_clear_timer(device);
+		cqr->status = DASD_CQR_CLEARED;
+		dasd_device_clear_timer(device);
 		wake_up(&dasd_flush_wq);
-		dasd_schedule_bh(device);
+		dasd_schedule_device_bh(device);
 		return;
 	}
 
@@ -1017,272 +1040,164 @@ dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 	}
 	DBF_DEV_EVENT(DBF_DEBUG, device, "Int: CS/DS 0x%04x for cqr %p",
 		      ((irb->scsw.cstat << 8) | irb->scsw.dstat), cqr);
-
- 	/* Find out the appropriate era_action. */
-	if (irb->scsw.fctl & SCSW_FCTL_HALT_FUNC)
-		era = dasd_era_fatal;
-	else if (irb->scsw.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&
-		 irb->scsw.cstat == 0 &&
-		 !irb->esw.esw0.erw.cons)
-		era = dasd_era_none;
-	else if (irb->esw.esw0.erw.cons)
-		era = device->discipline->examine_error(cqr, irb);
-	else
-		era = dasd_era_recover;
-
-	DBF_DEV_EVENT(DBF_DEBUG, device, "era_code %d", era);
+	next = NULL;
 	expires = 0;
-	if (era == dasd_era_none) {
-		cqr->status = DASD_CQR_DONE;
+	if (irb->scsw.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&
+	    irb->scsw.cstat == 0 && !irb->esw.esw0.erw.cons) {
+		/* request was completed successfully */
+		cqr->status = DASD_CQR_SUCCESS;
 		cqr->stopclk = now;
 		/* Start first request on queue if possible -> fast_io. */
-		if (cqr->list.next != &device->ccw_queue) {
-			next = list_entry(cqr->list.next,
-					  struct dasd_ccw_req, list);
-			if ((next->status == DASD_CQR_QUEUED) &&
-			    (!device->stopped)) {
-				if (device->discipline->start_IO(next) == 0)
-					expires = next->expires;
-				else
-					DEV_MESSAGE(KERN_DEBUG, device, "%s",
-						    "Interrupt fastpath "
-						    "failed!");
-			}
+		if (cqr->devlist.next != &device->ccw_queue) {
+			next = list_entry(cqr->devlist.next,
+					  struct dasd_ccw_req, devlist);
 		}
-	} else {		/* error */
-		memcpy(&cqr->irb, irb, sizeof (struct irb));
+	} else {  /* error */
+		memcpy(&cqr->irb, irb, sizeof(struct irb));
 		if (device->features & DASD_FEATURE_ERPLOG) {
-			/* dump sense data */
 			dasd_log_sense(cqr, irb);
 		}
-		switch (era) {
-		case dasd_era_fatal:
-			cqr->status = DASD_CQR_FAILED;
-			cqr->stopclk = now;
-			break;
-		case dasd_era_recover:
+		/* If we have no sense data, or we just don't want complex ERP
+		 * for this request, but if we have retries left, then just
+		 * reset this request and retry it in the fastpath
+		 */
+		if (!(cqr->irb.esw.esw0.erw.cons &&
+		      test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags)) &&
+		    cqr->retries > 0) {
+			DEV_MESSAGE(KERN_DEBUG, device,
+				    "default ERP in fastpath (%i retries left)",
+				    cqr->retries);
+			cqr->lpm    = LPM_ANYPATH;
+			cqr->status = DASD_CQR_QUEUED;
+			next = cqr;
+		} else
 			cqr->status = DASD_CQR_ERROR;
-			break;
-		default:
-			BUG();
-		}
+	}
+	if (next && (next->status == DASD_CQR_QUEUED) &&
+	    (!device->stopped)) {
+		if (device->discipline->start_IO(next) == 0)
+			expires = next->expires;
+		else
+			DEV_MESSAGE(KERN_DEBUG, device, "%s",
+				    "Interrupt fastpath "
+				    "failed!");
 	}
 	if (expires != 0)
-		dasd_set_timer(device, expires);
+		dasd_device_set_timer(device, expires);
 	else
-		dasd_clear_timer(device);
-	dasd_schedule_bh(device);
+		dasd_device_clear_timer(device);
+	dasd_schedule_device_bh(device);
 }
 
 /*
- * posts the buffer_cache about a finalized request
+ * If we have an error on a dasd_block layer request then we cancel
+ * and return all further requests from the same dasd_block as well.
  */
-static inline void
-dasd_end_request(struct request *req, int uptodate)
+static void __dasd_device_recovery(struct dasd_device *device,
+				   struct dasd_ccw_req *ref_cqr)
 {
-	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
-		BUG();
-	add_disk_randomness(req->rq_disk);
-	end_that_request_last(req, uptodate);
-}
+	struct list_head *l, *n;
+	struct dasd_ccw_req *cqr;
 
-/*
- * Process finished error recovery ccw.
- */
-static inline void
-__dasd_process_erp(struct dasd_device *device, struct dasd_ccw_req *cqr)
-{
-	dasd_erp_fn_t erp_fn;
+	/*
+	 * only requeue request that came from the dasd_block layer
+	 */
+	if (!ref_cqr->block)
+		return;
 
-	if (cqr->status == DASD_CQR_DONE)
-		DBF_DEV_EVENT(DBF_NOTICE, device, "%s", "ERP successful");
-	else
-		DEV_MESSAGE(KERN_ERR, device, "%s", "ERP unsuccessful");
-	erp_fn = device->discipline->erp_postaction(cqr);
-	erp_fn(cqr);
-}
+	list_for_each_safe(l, n, &device->ccw_queue) {
+		cqr = list_entry(l, struct dasd_ccw_req, devlist);
+		if (cqr->status == DASD_CQR_QUEUED &&
+		    ref_cqr->block == cqr->block) {
+			cqr->status = DASD_CQR_CLEARED;
+		}
+	}
+};
 
 /*
- * Process ccw request queue.
+ * Remove those ccw requests from the queue that need to be returned
+ * to the upper layer.
  */
-static void
-__dasd_process_ccw_queue(struct dasd_device * device,
-			 struct list_head *final_queue)
+static void __dasd_device_process_ccw_queue(struct dasd_device *device,
+					    struct list_head *final_queue)
 {
 	struct list_head *l, *n;
 	struct dasd_ccw_req *cqr;
-	dasd_erp_fn_t erp_fn;
 
-restart:
 	/* Process request with final status. */
 	list_for_each_safe(l, n, &device->ccw_queue) {
-		cqr = list_entry(l, struct dasd_ccw_req, list);
+		cqr = list_entry(l, struct dasd_ccw_req, devlist);
+
 		/* Stop list processing at the first non-final request. */
-		if (cqr->status != DASD_CQR_DONE &&
-		    cqr->status != DASD_CQR_FAILED &&
-		    cqr->status != DASD_CQR_ERROR)
+		if (cqr->status == DASD_CQR_QUEUED ||
+		    cqr->status == DASD_CQR_IN_IO ||
+		    cqr->status == DASD_CQR_CLEAR_PENDING)
 			break;
-		/*  Process requests with DASD_CQR_ERROR */
 		if (cqr->status == DASD_CQR_ERROR) {
-			if (cqr->irb.scsw.fctl & SCSW_FCTL_HALT_FUNC) {
-				cqr->status = DASD_CQR_FAILED;
-				cqr->stopclk = get_clock();
-			} else {
-				if (cqr->irb.esw.esw0.erw.cons &&
-				    test_bit(DASD_CQR_FLAGS_USE_ERP,
-					     &cqr->flags)) {
-					erp_fn = device->discipline->
-						erp_action(cqr);
-					erp_fn(cqr);
-				} else
-					dasd_default_erp_action(cqr);
-			}
-			goto restart;
-		}
-
-		/* First of all call extended error reporting. */
-		if (dasd_eer_enabled(device) &&
-		    cqr->status == DASD_CQR_FAILED) {
-			dasd_eer_write(device, cqr, DASD_EER_FATALERROR);
-
-			/* restart request  */
-			cqr->status = DASD_CQR_QUEUED;
-			cqr->retries = 255;
-			device->stopped |= DASD_STOPPED_QUIESCE;
-			goto restart;
+			__dasd_device_recovery(device, cqr);
 		}
-
-		/* Process finished ERP request. */
-		if (cqr->refers) {
-			__dasd_process_erp(device, cqr);
-			goto restart;
-		}
-
 		/* Rechain finished requests to final queue */
-		cqr->endclk = get_clock();
-		list_move_tail(&cqr->list, final_queue);
+		list_move_tail(&cqr->devlist, final_queue);
 	}
 }
 
-static void
-dasd_end_request_cb(struct dasd_ccw_req * cqr, void *data)
-{
-	struct request *req;
-	struct dasd_device *device;
-	int status;
-
-	req = (struct request *) data;
-	device = cqr->device;
-	dasd_profile_end(device, cqr, req);
-	status = cqr->device->discipline->free_cp(cqr,req);
-	spin_lock_irq(&device->request_queue_lock);
-	dasd_end_request(req, status);
-	spin_unlock_irq(&device->request_queue_lock);
-}
-
-
 /*
- * Fetch requests from the block device queue.
+ * the cqrs from the final queue are returned to the upper layer
+ * by setting a dasd_block state and calling the callback function
  */
-static void
-__dasd_process_blk_queue(struct dasd_device * device)
+static void __dasd_device_process_final_queue(struct dasd_device *device,
+					      struct list_head *final_queue)
 {
-	struct request_queue *queue;
-	struct request *req;
+	struct list_head *l, *n;
 	struct dasd_ccw_req *cqr;
-	int nr_queued;
-
-	queue = device->request_queue;
-	/* No queue ? Then there is nothing to do. */
-	if (queue == NULL)
-		return;
-
-	/*
-	 * We requeue request from the block device queue to the ccw
-	 * queue only in two states. In state DASD_STATE_READY the
-	 * partition detection is done and we need to requeue requests
-	 * for that. State DASD_STATE_ONLINE is normal block device
-	 * operation.
-	 */
-	if (device->state != DASD_STATE_READY &&
-	    device->state != DASD_STATE_ONLINE)
-		return;
-	nr_queued = 0;
-	/* Now we try to fetch requests from the request queue */
-	list_for_each_entry(cqr, &device->ccw_queue, list)
-		if (cqr->status == DASD_CQR_QUEUED)
-			nr_queued++;
-	while (!blk_queue_plugged(queue) &&
-	       elv_next_request(queue) &&
-		nr_queued < DASD_CHANQ_MAX_SIZE) {
-		req = elv_next_request(queue);
 
-		if (device->features & DASD_FEATURE_READONLY &&
-		    rq_data_dir(req) == WRITE) {
-			DBF_DEV_EVENT(DBF_ERR, device,
-				      "Rejecting write request %p",
-				      req);
-			blkdev_dequeue_request(req);
-			dasd_end_request(req, 0);
-			continue;
-		}
-		if (device->stopped & DASD_STOPPED_DC_EIO) {
-			blkdev_dequeue_request(req);
-			dasd_end_request(req, 0);
-			continue;
-		}
-		cqr = device->discipline->build_cp(device, req);
-		if (IS_ERR(cqr)) {
-			if (PTR_ERR(cqr) == -ENOMEM)
-				break;	/* terminate request queue loop */
-			if (PTR_ERR(cqr) == -EAGAIN) {
-				/*
-				 * The current request cannot be build right
-				 * now, we have to try later. If this request
-				 * is the head-of-queue we stop the device
-				 * for 1/2 second.
-				 */
-				if (!list_empty(&device->ccw_queue))
-					break;
-				device->stopped |= DASD_STOPPED_PENDING;
-				dasd_set_timer(device, HZ/2);
-				break;
-			}
-			DBF_DEV_EVENT(DBF_ERR, device,
-				      "CCW creation failed (rc=%ld) "
-				      "on request %p",
-				      PTR_ERR(cqr), req);
-			blkdev_dequeue_request(req);
-			dasd_end_request(req, 0);
-			continue;
+	list_for_each_safe(l, n, final_queue) {
+		cqr = list_entry(l, struct dasd_ccw_req, devlist);
+		list_del_init(&cqr->devlist);
+		if (cqr->block)
+			spin_lock_bh(&cqr->block->queue_lock);
+		switch (cqr->status) {
+		case DASD_CQR_SUCCESS:
+			cqr->status = DASD_CQR_DONE;
+			break;
+		case DASD_CQR_ERROR:
+			cqr->status = DASD_CQR_NEED_ERP;
+			break;
+		case DASD_CQR_CLEARED:
+			cqr->status = DASD_CQR_TERMINATED;
+			break;
+		default:
+			DEV_MESSAGE(KERN_ERR, device,
+				    "wrong cqr status in __dasd_process_final_queue "
+				    "for cqr %p, status %x",
+				    cqr, cqr->status);
+			BUG();
 		}
-		cqr->callback = dasd_end_request_cb;
-		cqr->callback_data = (void *) req;
-		cqr->status = DASD_CQR_QUEUED;
-		blkdev_dequeue_request(req);
-		list_add_tail(&cqr->list, &device->ccw_queue);
-		dasd_profile_start(device, cqr, req);
-		nr_queued++;
+		if (cqr->block)
+			spin_unlock_bh(&cqr->block->queue_lock);
+		if (cqr->callback != NULL)
+			(cqr->callback)(cqr, cqr->callback_data);
 	}
 }
 
+
+
 /*
  * Take a look at the first request on the ccw queue and check
  * if it reached its expire time. If so, terminate the IO.
  */
-static void
-__dasd_check_expire(struct dasd_device * device)
+static void __dasd_device_check_expire(struct dasd_device *device)
 {
 	struct dasd_ccw_req *cqr;
 
 	if (list_empty(&device->ccw_queue))
 		return;
-	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
+	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, devlist);
 	if ((cqr->status == DASD_CQR_IN_IO && cqr->expires != 0) &&
 	    (time_after_eq(jiffies, cqr->expires + cqr->starttime))) {
 		if (device->discipline->term_IO(cqr) != 0) {
 			/* Hmpf, try again in 5 sec */
-			dasd_set_timer(device, 5*HZ);
+			dasd_device_set_timer(device, 5*HZ);
 			DEV_MESSAGE(KERN_ERR, device,
 				    "internal error - timeout (%is) expired "
 				    "for cqr %p, termination failed, "
@@ -1301,77 +1216,53 @@ __dasd_check_expire(struct dasd_device * device)
  * Take a look at the first request on the ccw queue and check
  * if it needs to be started.
  */
-static void
-__dasd_start_head(struct dasd_device * device)
+static void __dasd_device_start_head(struct dasd_device *device)
 {
 	struct dasd_ccw_req *cqr;
 	int rc;
 
 	if (list_empty(&device->ccw_queue))
 		return;
-	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
+	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, devlist);
 	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);
+	/* when device is stopped, return request to previous layer */
+	if (device->stopped) {
+		cqr->status = DASD_CQR_CLEARED;
+		dasd_schedule_device_bh(device);
 		return;
 	}
-	/* 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);
+		dasd_device_set_timer(device, cqr->expires);
 	else if (rc == -EACCES) {
-		dasd_schedule_bh(device);
+		dasd_schedule_device_bh(device);
 	} else
 		/* Hmpf, try again in 1/2 sec */
-		dasd_set_timer(device, 50);
-}
-
-static inline int
-_wait_for_clear(struct dasd_ccw_req *cqr)
-{
-	return (cqr->status == DASD_CQR_QUEUED);
+		dasd_device_set_timer(device, 50);
 }
 
 /*
- * Remove all requests from the ccw queue (all = '1') or only block device
- * requests in case all = '0'.
- * Take care of the erp-chain (chained via cqr->refers) and remove either
- * the whole erp-chain or none of the erp-requests.
- * If a request is currently running, term_IO is called and the request
- * is re-queued. Prior to removing the terminated request we need to wait
- * for the clear-interrupt.
- * In case termination is not possible we stop processing and just finishing
- * the already moved requests.
+ * Go through all request on the dasd_device request queue,
+ * terminate them on the cdev if necessary, and return them to the
+ * submitting layer via callback.
+ * Note:
+ * Make sure that all 'submitting layers' still exist when
+ * this function is called!. In other words, when 'device' is a base
+ * device then all block layer requests must have been removed before
+ * via dasd_flush_block_queue.
  */
-static int
-dasd_flush_ccw_queue(struct dasd_device * device, int all)
+int dasd_flush_device_queue(struct dasd_device *device)
 {
-	struct dasd_ccw_req *cqr, *orig, *n;
-	int rc, i;
-
+	struct dasd_ccw_req *cqr, *n;
+	int rc;
 	struct list_head flush_queue;
 
 	INIT_LIST_HEAD(&flush_queue);
 	spin_lock_irq(get_ccwdev_lock(device->cdev));
 	rc = 0;
-restart:
-	list_for_each_entry_safe(cqr, n, &device->ccw_queue, list) {
-		/* get original request of erp request-chain */
-		for (orig = cqr; orig->refers != NULL; orig = orig->refers);
-
-		/* Flush all request or only block device requests? */
-		if (all == 0 && cqr->callback != dasd_end_request_cb &&
-		    orig->callback != dasd_end_request_cb) {
-			continue;
-		}
+	list_for_each_entry_safe(cqr, n, &device->ccw_queue, devlist) {
 		/* Check status and move request to flush_queue */
 		switch (cqr->status) {
 		case DASD_CQR_IN_IO:
@@ -1387,90 +1278,60 @@ restart:
 			}
 			break;
 		case DASD_CQR_QUEUED:
-		case DASD_CQR_ERROR:
-			/* set request to FAILED */
 			cqr->stopclk = get_clock();
-			cqr->status = DASD_CQR_FAILED;
+			cqr->status = DASD_CQR_CLEARED;
 			break;
-		default: /* do not touch the others */
+		default: /* no need to modify the others */
 			break;
 		}
-		/* Rechain request (including erp chain) */
-		for (i = 0; cqr != NULL; cqr = cqr->refers, i++) {
-			cqr->endclk = get_clock();
-			list_move_tail(&cqr->list, &flush_queue);
-		}
-		if (i > 1)
-			/* moved more than one request - need to restart */
-			goto restart;
+		list_move_tail(&cqr->devlist, &flush_queue);
 	}
-
 finished:
 	spin_unlock_irq(get_ccwdev_lock(device->cdev));
-	/* Now call the callback function of flushed requests */
-restart_cb:
-	list_for_each_entry_safe(cqr, n, &flush_queue, list) {
-		if (cqr->status == DASD_CQR_CLEAR) {
-			/* wait for clear interrupt! */
-			wait_event(dasd_flush_wq, _wait_for_clear(cqr));
-			cqr->status = DASD_CQR_FAILED;
-		}
-		/* Process finished ERP request. */
-		if (cqr->refers) {
-			__dasd_process_erp(device, cqr);
-			/* restart list_for_xx loop since dasd_process_erp
-			 * might remove multiple elements */
-			goto restart_cb;
-		}
-		/* call the callback function */
-		cqr->endclk = get_clock();
-		if (cqr->callback != NULL)
-			(cqr->callback)(cqr, cqr->callback_data);
-	}
+	/*
+	 * After this point all requests must be in state CLEAR_PENDING,
+	 * CLEARED, SUCCESS or ERROR. Now wait for CLEAR_PENDING to become
+	 * one of the others.
+	 */
+	list_for_each_entry_safe(cqr, n, &flush_queue, devlist)
+		wait_event(dasd_flush_wq,
+			   (cqr->status != DASD_CQR_CLEAR_PENDING));
+	/*
+	 * Now set each request back to TERMINATED, DONE or NEED_ERP
+	 * and call the callback function of flushed requests
+	 */
+	__dasd_device_process_final_queue(device, &flush_queue);
 	return rc;
 }
 
 /*
  * Acquire the device lock and process queues for the device.
  */
-static void
-dasd_tasklet(struct dasd_device * device)
+static void dasd_device_tasklet(struct dasd_device *device)
 {
 	struct list_head final_queue;
-	struct list_head *l, *n;
-	struct dasd_ccw_req *cqr;
 
 	atomic_set (&device->tasklet_scheduled, 0);
 	INIT_LIST_HEAD(&final_queue);
 	spin_lock_irq(get_ccwdev_lock(device->cdev));
 	/* Check expire time of first request on the ccw queue. */
-	__dasd_check_expire(device);
-	/* Finish off requests on ccw queue */
-	__dasd_process_ccw_queue(device, &final_queue);
+	__dasd_device_check_expire(device);
+	/* find final requests on ccw queue */
+	__dasd_device_process_ccw_queue(device, &final_queue);
 	spin_unlock_irq(get_ccwdev_lock(device->cdev));
 	/* Now call the callback function of requests with final status */
-	list_for_each_safe(l, n, &final_queue) {
-		cqr = list_entry(l, struct dasd_ccw_req, list);
-		list_del_init(&cqr->list);
-		if (cqr->callback != NULL)
-			(cqr->callback)(cqr, cqr->callback_data);
-	}
-	spin_lock_irq(&device->request_queue_lock);
-	spin_lock(get_ccwdev_lock(device->cdev));
-	/* Get new request from the block device request queue */
-	__dasd_process_blk_queue(device);
+	__dasd_device_process_final_queue(device, &final_queue);
+	spin_lock_irq(get_ccwdev_lock(device->cdev));
 	/* Now check if the head of the ccw queue needs to be started. */
-	__dasd_start_head(device);
-	spin_unlock(get_ccwdev_lock(device->cdev));
-	spin_unlock_irq(&device->request_queue_lock);
+	__dasd_device_start_head(device);
+	spin_unlock_irq(get_ccwdev_lock(device->cdev));
 	dasd_put_device(device);
 }
 
 /*
  * Schedules a call to dasd_tasklet over the device tasklet.
  */
-void
-dasd_schedule_bh(struct dasd_device * device)
+void dasd_schedule_device_bh(struct dasd_device *device)
 {
 	/* Protect against rescheduling. */
 	if (atomic_cmpxchg (&device->tasklet_scheduled, 0, 1) != 0)
@@ -1480,160 +1341,109 @@ dasd_schedule_bh(struct dasd_device * device)
 }
 
 /*
- * Queue a request to the head of the ccw_queue. Start the I/O if
- * possible.
+ * Queue a request to the head of the device ccw_queue.
+ * Start the I/O if possible.
  */
-void
-dasd_add_request_head(struct dasd_ccw_req *req)
+void dasd_add_request_head(struct dasd_ccw_req *cqr)
 {
 	struct dasd_device *device;
 	unsigned long flags;
 
-	device = req->device;
+	device = cqr->startdev;
 	spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
-	req->status = DASD_CQR_QUEUED;
-	req->device = device;
-	list_add(&req->list, &device->ccw_queue);
+	cqr->status = DASD_CQR_QUEUED;
+	list_add(&cqr->devlist, &device->ccw_queue);
 	/* let the bh start the request to keep them in order */
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
 	spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 }
 
 /*
- * Queue a request to the tail of the ccw_queue. Start the I/O if
- * possible.
+ * Queue a request to the tail of the device ccw_queue.
+ * Start the I/O if possible.
  */
-void
-dasd_add_request_tail(struct dasd_ccw_req *req)
+void dasd_add_request_tail(struct dasd_ccw_req *cqr)
 {
 	struct dasd_device *device;
 	unsigned long flags;
 
-	device = req->device;
+	device = cqr->startdev;
 	spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
-	req->status = DASD_CQR_QUEUED;
-	req->device = device;
-	list_add_tail(&req->list, &device->ccw_queue);
+	cqr->status = DASD_CQR_QUEUED;
+	list_add_tail(&cqr->devlist, &device->ccw_queue);
 	/* let the bh start the request to keep them in order */
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
 	spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 }
 
 /*
- * Wakeup callback.
+ * Wakeup helper for the 'sleep_on' functions.
  */
-static void
-dasd_wakeup_cb(struct dasd_ccw_req *cqr, void *data)
+static void dasd_wakeup_cb(struct dasd_ccw_req *cqr, void *data)
 {
 	wake_up((wait_queue_head_t *) data);
 }
 
-static inline int
-_wait_for_wakeup(struct dasd_ccw_req *cqr)
+static inline int _wait_for_wakeup(struct dasd_ccw_req *cqr)
 {
 	struct dasd_device *device;
 	int rc;
 
-	device = cqr->device;
+	device = cqr->startdev;
 	spin_lock_irq(get_ccwdev_lock(device->cdev));
 	rc = ((cqr->status == DASD_CQR_DONE ||
-	       cqr->status == DASD_CQR_FAILED) &&
-	      list_empty(&cqr->list));
+	       cqr->status == DASD_CQR_NEED_ERP ||
+	       cqr->status == DASD_CQR_TERMINATED) &&
+	      list_empty(&cqr->devlist));
 	spin_unlock_irq(get_ccwdev_lock(device->cdev));
 	return rc;
 }
 
 /*
- * Attempts to start a special ccw queue and waits for its completion.
+ * 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)
+int dasd_sleep_on(struct dasd_ccw_req *cqr)
 {
 	wait_queue_head_t wait_q;
 	struct dasd_device *device;
 	int rc;
 
-	device = cqr->device;
-	spin_lock_irq(get_ccwdev_lock(device->cdev));
+	device = cqr->startdev;
 
 	init_waitqueue_head (&wait_q);
 	cqr->callback = dasd_wakeup_cb;
 	cqr->callback_data = (void *) &wait_q;
-	cqr->status = DASD_CQR_QUEUED;
-	list_add_tail(&cqr->list, &device->ccw_queue);
-
-	/* let the bh start the request to keep them in order */
-	dasd_schedule_bh(device);
-
-	spin_unlock_irq(get_ccwdev_lock(device->cdev));
-
+	dasd_add_request_tail(cqr);
 	wait_event(wait_q, _wait_for_wakeup(cqr));
 
 	/* Request status is either done or failed. */
-	rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
+	rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
 	return rc;
 }
 
 /*
- * Attempts to start a special ccw queue and wait interruptible
- * for its completion.
+ * 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)
+int dasd_sleep_on_interruptible(struct dasd_ccw_req *cqr)
 {
 	wait_queue_head_t wait_q;
 	struct dasd_device *device;
-	int rc, finished;
-
-	device = cqr->device;
-	spin_lock_irq(get_ccwdev_lock(device->cdev));
+	int rc;
 
+	device = cqr->startdev;
 	init_waitqueue_head (&wait_q);
 	cqr->callback = dasd_wakeup_cb;
 	cqr->callback_data = (void *) &wait_q;
-	cqr->status = DASD_CQR_QUEUED;
-	list_add_tail(&cqr->list, &device->ccw_queue);
-
-	/* let the bh start the request to keep them in order */
-	dasd_schedule_bh(device);
-	spin_unlock_irq(get_ccwdev_lock(device->cdev));
-
-	finished = 0;
-	while (!finished) {
-		rc = wait_event_interruptible(wait_q, _wait_for_wakeup(cqr));
-		if (rc != -ERESTARTSYS) {
-			/* Request is final (done or failed) */
-			rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
-			break;
-		}
-		spin_lock_irq(get_ccwdev_lock(device->cdev));
-		switch (cqr->status) {
-		case DASD_CQR_IN_IO:
-                        /* terminate runnig cqr */
-			if (device->discipline->term_IO) {
-				cqr->retries = -1;
-				device->discipline->term_IO(cqr);
-				/* wait (non-interruptible) for final status
-				 * because signal ist still pending */
-				spin_unlock_irq(get_ccwdev_lock(device->cdev));
-				wait_event(wait_q, _wait_for_wakeup(cqr));
-				spin_lock_irq(get_ccwdev_lock(device->cdev));
-				rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
-				finished = 1;
-			}
-			break;
-		case DASD_CQR_QUEUED:
-			/* request  */
-			list_del_init(&cqr->list);
-			rc = -EIO;
-			finished = 1;
-			break;
-		default:
-			/* cqr with 'non-interruptable' status - just wait */
-			break;
-		}
-		spin_unlock_irq(get_ccwdev_lock(device->cdev));
+	dasd_add_request_tail(cqr);
+	rc = wait_event_interruptible(wait_q, _wait_for_wakeup(cqr));
+	if (rc == -ERESTARTSYS) {
+		dasd_cancel_req(cqr);
+		/* wait (non-interruptible) for final status */
+		wait_event(wait_q, _wait_for_wakeup(cqr));
 	}
+	rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
 	return rc;
 }
 
@@ -1643,25 +1453,23 @@ dasd_sleep_on_interruptible(struct dasd_ccw_req * cqr)
  * and be put back to status queued, before the special request is added
  * to the head of the queue. Then the special request is waited on normally.
  */
-static inline int
-_dasd_term_running_cqr(struct dasd_device *device)
+static inline int _dasd_term_running_cqr(struct dasd_device *device)
 {
 	struct dasd_ccw_req *cqr;
 
 	if (list_empty(&device->ccw_queue))
 		return 0;
-	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
+	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, devlist);
 	return device->discipline->term_IO(cqr);
 }
 
-int
-dasd_sleep_on_immediatly(struct dasd_ccw_req * cqr)
+int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr)
 {
 	wait_queue_head_t wait_q;
 	struct dasd_device *device;
 	int rc;
 
-	device = cqr->device;
+	device = cqr->startdev;
 	spin_lock_irq(get_ccwdev_lock(device->cdev));
 	rc = _dasd_term_running_cqr(device);
 	if (rc) {
@@ -1673,17 +1481,17 @@ dasd_sleep_on_immediatly(struct dasd_ccw_req * cqr)
 	cqr->callback = dasd_wakeup_cb;
 	cqr->callback_data = (void *) &wait_q;
 	cqr->status = DASD_CQR_QUEUED;
-	list_add(&cqr->list, &device->ccw_queue);
+	list_add(&cqr->devlist, &device->ccw_queue);
 
 	/* let the bh start the request to keep them in order */
-	dasd_schedule_bh(device);
+	dasd_schedule_device_bh(device);
 
 	spin_unlock_irq(get_ccwdev_lock(device->cdev));
 
 	wait_event(wait_q, _wait_for_wakeup(cqr));
 
 	/* Request status is either done or failed. */
-	rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
+	rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
 	return rc;
 }
 
@@ -1692,11 +1500,14 @@ dasd_sleep_on_immediatly(struct dasd_ccw_req * cqr)
  * This is useful to timeout requests. The request will be
  * terminated if it is currently in i/o.
  * Returns 1 if the request has been terminated.
+ *	   0 if there was no need to terminate the request (not started yet)
+ *	   negative error code if termination failed
+ * Cancellation of a request is an asynchronous operation! The calling
+ * function has to wait until the request is properly returned via callback.
  */
-int
-dasd_cancel_req(struct dasd_ccw_req *cqr)
+int dasd_cancel_req(struct dasd_ccw_req *cqr)
 {
-	struct dasd_device *device = cqr->device;
+	struct dasd_device *device = cqr->startdev;
 	unsigned long flags;
 	int rc;
 
@@ -1704,74 +1515,453 @@ dasd_cancel_req(struct dasd_ccw_req *cqr)
 	spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 	switch (cqr->status) {
 	case DASD_CQR_QUEUED:
-		/* request was not started - just set to failed */
-		cqr->status = DASD_CQR_FAILED;
+		/* request was not started - just set to cleared */
+		cqr->status = DASD_CQR_CLEARED;
 		break;
 	case DASD_CQR_IN_IO:
 		/* request in IO - terminate IO and release again */
-		if (device->discipline->term_IO(cqr) != 0)
-			/* what to do if unable to terminate ??????
-			   e.g. not _IN_IO */
-			cqr->status = DASD_CQR_FAILED;
-		cqr->stopclk = get_clock();
-		rc = 1;
+		rc = device->discipline->term_IO(cqr);
+		if (rc) {
+			DEV_MESSAGE(KERN_ERR, device,
+				    "dasd_cancel_req is unable "
+				    " to terminate request %p, rc = %d",
+				    cqr, rc);
+		} else {
+			cqr->stopclk = get_clock();
+			rc = 1;
+		}
 		break;
-	case DASD_CQR_DONE:
-	case DASD_CQR_FAILED:
-		/* already finished - do nothing */
+	default: /* already finished or clear pending - do nothing */
 		break;
-	default:
-		DEV_MESSAGE(KERN_ALERT, device,
-			    "invalid status %02x in request",
-			    cqr->status);
+	}
+	spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
+	dasd_schedule_device_bh(device);
+	return rc;
+}
+
+
+/*
+ * SECTION: Operations of the dasd_block layer.
+ */
+
+/*
+ * Timeout function for dasd_block. This is used when the block layer
+ * is waiting for something that may not come reliably, (e.g. a state
+ * change interrupt)
+ */
+static void dasd_block_timeout(unsigned long ptr)
+{
+	unsigned long flags;
+	struct dasd_block *block;
+
+	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;
+	spin_unlock_irqrestore(get_ccwdev_lock(block->base->cdev), flags);
+	dasd_schedule_block_bh(block);
+}
+
+/*
+ * Setup timeout for a dasd_block in jiffies.
+ */
+void dasd_block_set_timer(struct dasd_block *block, int expires)
+{
+	if (expires == 0) {
+		if (timer_pending(&block->timer))
+			del_timer(&block->timer);
+		return;
+	}
+	if (timer_pending(&block->timer)) {
+		if (mod_timer(&block->timer, jiffies + expires))
+			return;
+	}
+	block->timer.function = dasd_block_timeout;
+	block->timer.data = (unsigned long) block;
+	block->timer.expires = jiffies + expires;
+	add_timer(&block->timer);
+}
+
+/*
+ * Clear timeout for a dasd_block.
+ */
+void dasd_block_clear_timer(struct dasd_block *block)
+{
+	if (timer_pending(&block->timer))
+		del_timer(&block->timer);
+}
+
+/*
+ * posts the buffer_cache about a finalized request
+ */
+static inline void dasd_end_request(struct request *req, int uptodate)
+{
+	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
 		BUG();
+	add_disk_randomness(req->rq_disk);
+	end_that_request_last(req, uptodate);
+}
 
+/*
+ * Process finished error recovery ccw.
+ */
+static inline void __dasd_block_process_erp(struct dasd_block *block,
+					    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");
+	else
+		DEV_MESSAGE(KERN_ERR, device, "%s", "ERP unsuccessful");
+	erp_fn = device->discipline->erp_postaction(cqr);
+	erp_fn(cqr);
+}
+
+/*
+ * Fetch requests from the block device queue.
+ */
+static void __dasd_process_request_queue(struct dasd_block *block)
+{
+	struct request_queue *queue;
+	struct request *req;
+	struct dasd_ccw_req *cqr;
+	struct dasd_device *basedev;
+	unsigned long flags;
+	queue = block->request_queue;
+	basedev = block->base;
+	/* No queue ? Then there is nothing to do. */
+	if (queue == NULL)
+		return;
+
+	/*
+	 * We requeue request from the block device queue to the ccw
+	 * queue only in two states. In state DASD_STATE_READY the
+	 * partition detection is done and we need to requeue requests
+	 * for that. State DASD_STATE_ONLINE is normal block device
+	 * operation.
+	 */
+	if (basedev->state < DASD_STATE_READY)
+		return;
+	/* Now we try to fetch requests from the request queue */
+	while (!blk_queue_plugged(queue) &&
+	       elv_next_request(queue)) {
+
+		req = elv_next_request(queue);
+
+		if (basedev->features & DASD_FEATURE_READONLY &&
+		    rq_data_dir(req) == WRITE) {
+			DBF_DEV_EVENT(DBF_ERR, basedev,
+				      "Rejecting write request %p",
+				      req);
+			blkdev_dequeue_request(req);
+			dasd_end_request(req, 0);
+			continue;
+		}
+		cqr = basedev->discipline->build_cp(basedev, block, req);
+		if (IS_ERR(cqr)) {
+			if (PTR_ERR(cqr) == -EBUSY)
+				break;	/* normal end condition */
+			if (PTR_ERR(cqr) == -ENOMEM)
+				break;	/* terminate request queue loop */
+			if (PTR_ERR(cqr) == -EAGAIN) {
+				/*
+				 * The current request cannot be build right
+				 * now, we have to try later. If this request
+				 * is the head-of-queue we stop the device
+				 * for 1/2 second.
+				 */
+				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);
+				dasd_block_set_timer(block, HZ/2);
+				break;
+			}
+			DBF_DEV_EVENT(DBF_ERR, basedev,
+				      "CCW creation failed (rc=%ld) "
+				      "on request %p",
+				      PTR_ERR(cqr), req);
+			blkdev_dequeue_request(req);
+			dasd_end_request(req, 0);
+			continue;
+		}
+		/*
+		 *  Note: callback is set to dasd_return_cqr_cb in
+		 * __dasd_block_start_head to cover erp requests as well
+		 */
+		cqr->callback_data = (void *) req;
+		cqr->status = DASD_CQR_FILLED;
+		blkdev_dequeue_request(req);
+		list_add_tail(&cqr->blocklist, &block->ccw_queue);
+		dasd_profile_start(block, cqr, req);
+	}
+}
+
+static void __dasd_cleanup_cqr(struct dasd_ccw_req *cqr)
+{
+	struct request *req;
+	int status;
+
+	req = (struct request *) cqr->callback_data;
+	dasd_profile_end(cqr->block, cqr, req);
+	status = cqr->memdev->discipline->free_cp(cqr, req);
+	dasd_end_request(req, status);
+}
+
+/*
+ * Process ccw request queue.
+ */
+static void __dasd_process_block_ccw_queue(struct dasd_block *block,
+					   struct list_head *final_queue)
+{
+	struct list_head *l, *n;
+	struct dasd_ccw_req *cqr;
+	dasd_erp_fn_t erp_fn;
+	unsigned long flags;
+	struct dasd_device *base = block->base;
+
+restart:
+	/* Process request with final status. */
+	list_for_each_safe(l, n, &block->ccw_queue) {
+		cqr = list_entry(l, struct dasd_ccw_req, blocklist);
+		if (cqr->status != DASD_CQR_DONE &&
+		    cqr->status != DASD_CQR_FAILED &&
+		    cqr->status != DASD_CQR_NEED_ERP &&
+		    cqr->status != DASD_CQR_TERMINATED)
+			continue;
+
+		if (cqr->status == DASD_CQR_TERMINATED) {
+			base->discipline->handle_terminated_request(cqr);
+			goto restart;
+		}
+
+		/*  Process requests that may be recovered */
+		if (cqr->status == DASD_CQR_NEED_ERP) {
+			if (cqr->irb.esw.esw0.erw.cons &&
+			    test_bit(DASD_CQR_FLAGS_USE_ERP,
+				     &cqr->flags)) {
+				erp_fn = base->discipline->erp_action(cqr);
+				erp_fn(cqr);
+			}
+			goto restart;
+		}
+
+		/* First of all call extended error reporting. */
+		if (dasd_eer_enabled(base) &&
+		    cqr->status == DASD_CQR_FAILED) {
+			dasd_eer_write(base, cqr, DASD_EER_FATALERROR);
+
+			/* restart request  */
+			cqr->status = DASD_CQR_FILLED;
+			cqr->retries = 255;
+			spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
+			base->stopped |= DASD_STOPPED_QUIESCE;
+			spin_unlock_irqrestore(get_ccwdev_lock(base->cdev),
+					       flags);
+			goto restart;
+		}
+
+		/* Process finished ERP request. */
+		if (cqr->refers) {
+			__dasd_block_process_erp(block, cqr);
+			goto restart;
+		}
+
+		/* Rechain finished requests to final queue */
+		cqr->endclk = get_clock();
+		list_move_tail(&cqr->blocklist, final_queue);
+	}
+}
+
+static void dasd_return_cqr_cb(struct dasd_ccw_req *cqr, void *data)
+{
+	dasd_schedule_block_bh(cqr->block);
+}
+
+static void __dasd_block_start_head(struct dasd_block *block)
+{
+	struct dasd_ccw_req *cqr;
+
+	if (list_empty(&block->ccw_queue))
+		return;
+	/* We allways begin with the first requests on the queue, as some
+	 * of previously started requests have to be enqueued on a
+	 * dasd_device again for error recovery.
+	 */
+	list_for_each_entry(cqr, &block->ccw_queue, blocklist) {
+		if (cqr->status != DASD_CQR_FILLED)
+			continue;
+		/* Non-temporary stop condition will trigger fail fast */
+		if (block->base->stopped & ~DASD_STOPPED_PENDING &&
+		    test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
+		    (!dasd_eer_enabled(block->base))) {
+			cqr->status = DASD_CQR_FAILED;
+			dasd_schedule_block_bh(block);
+			continue;
+		}
+		/* Don't try to start requests if device is stopped */
+		if (block->base->stopped)
+			return;
+
+		/* just a fail safe check, should not happen */
+		if (!cqr->startdev)
+			cqr->startdev = block->base;
+
+		/* make sure that the requests we submit find their way back */
+		cqr->callback = dasd_return_cqr_cb;
+
+		dasd_add_request_tail(cqr);
+	}
+}
+
+/*
+ * Central dasd_block layer routine. Takes requests from the generic
+ * block layer request queue, creates ccw requests, enqueues them on
+ * a dasd_device and processes ccw requests that have been returned.
+ */
+static void dasd_block_tasklet(struct dasd_block *block)
+{
+	struct list_head final_queue;
+	struct list_head *l, *n;
+	struct dasd_ccw_req *cqr;
+
+	atomic_set(&block->tasklet_scheduled, 0);
+	INIT_LIST_HEAD(&final_queue);
+	spin_lock(&block->queue_lock);
+	/* Finish off requests on ccw queue */
+	__dasd_process_block_ccw_queue(block, &final_queue);
+	spin_unlock(&block->queue_lock);
+	/* Now call the callback function of requests with final status */
+	spin_lock_irq(&block->request_queue_lock);
+	list_for_each_safe(l, n, &final_queue) {
+		cqr = list_entry(l, struct dasd_ccw_req, blocklist);
+		list_del_init(&cqr->blocklist);
+		__dasd_cleanup_cqr(cqr);
+	}
+	spin_lock(&block->queue_lock);
+	/* Get new request from the block device request queue */
+	__dasd_process_request_queue(block);
+	/* Now check if the head of the ccw queue needs to be started. */
+	__dasd_block_start_head(block);
+	spin_unlock(&block->queue_lock);
+	spin_unlock_irq(&block->request_queue_lock);
+	dasd_put_device(block->base);
+}
+
+static void _dasd_wake_block_flush_cb(struct dasd_ccw_req *cqr, void *data)
+{
+	wake_up(&dasd_flush_wq);
+}
+
+/*
+ * Go through all request on the dasd_block request queue, cancel them
+ * on the respective dasd_device, and return them to the generic
+ * block layer.
+ */
+static int dasd_flush_block_queue(struct dasd_block *block)
+{
+	struct dasd_ccw_req *cqr, *n;
+	int rc, i;
+	struct list_head flush_queue;
+
+	INIT_LIST_HEAD(&flush_queue);
+	spin_lock_bh(&block->queue_lock);
+	rc = 0;
+restart:
+	list_for_each_entry_safe(cqr, n, &block->ccw_queue, blocklist) {
+		/* if this request currently owned by a dasd_device cancel it */
+		if (cqr->status >= DASD_CQR_QUEUED)
+			rc = dasd_cancel_req(cqr);
+		if (rc < 0)
+			break;
+		/* Rechain request (including erp chain) so it won't be
+		 * touched by the dasd_block_tasklet anymore.
+		 * Replace the callback so we notice when the request
+		 * is returned from the dasd_device layer.
+		 */
+		cqr->callback = _dasd_wake_block_flush_cb;
+		for (i = 0; cqr != NULL; cqr = cqr->refers, i++)
+			list_move_tail(&cqr->blocklist, &flush_queue);
+		if (i > 1)
+			/* moved more than one request - need to restart */
+			goto restart;
+	}
+	spin_unlock_bh(&block->queue_lock);
+	/* Now call the callback function of flushed requests */
+restart_cb:
+	list_for_each_entry_safe(cqr, n, &flush_queue, blocklist) {
+		wait_event(dasd_flush_wq, (cqr->status < DASD_CQR_QUEUED));
+		/* Process finished ERP request. */
+		if (cqr->refers) {
+			__dasd_block_process_erp(block, cqr);
+			/* restart list_for_xx loop since dasd_process_erp
+			 * might remove multiple elements */
+			goto restart_cb;
+		}
+		/* call the callback function */
+		cqr->endclk = get_clock();
+		list_del_init(&cqr->blocklist);
+		__dasd_cleanup_cqr(cqr);
 	}
-	spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
-	dasd_schedule_bh(device);
 	return rc;
 }
 
 /*
- * SECTION: Block device operations (request queue, partitions, open, release).
+ * Schedules a call to dasd_tasklet over the device tasklet.
+ */
+void dasd_schedule_block_bh(struct dasd_block *block)
+{
+	/* Protect against rescheduling. */
+	if (atomic_cmpxchg(&block->tasklet_scheduled, 0, 1) != 0)
+		return;
+	/* life cycle of block is bound to it's base device */
+	dasd_get_device(block->base);
+	tasklet_hi_schedule(&block->tasklet);
+}
+
+
+/*
+ * SECTION: external block device operations
+ * (request queue handling, open, release, etc.)
  */
 
 /*
  * Dasd request queue function. Called from ll_rw_blk.c
  */
-static void
-do_dasd_request(struct request_queue * queue)
+static void do_dasd_request(struct request_queue *queue)
 {
-	struct dasd_device *device;
+	struct dasd_block *block;
 
-	device = (struct dasd_device *) queue->queuedata;
-	spin_lock(get_ccwdev_lock(device->cdev));
+	block = queue->queuedata;
+	spin_lock(&block->queue_lock);
 	/* Get new request from the block device request queue */
-	__dasd_process_blk_queue(device);
+	__dasd_process_request_queue(block);
 	/* Now check if the head of the ccw queue needs to be started. */
-	__dasd_start_head(device);
-	spin_unlock(get_ccwdev_lock(device->cdev));
+	__dasd_block_start_head(block);
+	spin_unlock(&block->queue_lock);
 }
 
 /*
  * Allocate and initialize request queue and default I/O scheduler.
  */
-static int
-dasd_alloc_queue(struct dasd_device * device)
+static int dasd_alloc_queue(struct dasd_block *block)
 {
 	int rc;
 
-	device->request_queue = blk_init_queue(do_dasd_request,
-					       &device->request_queue_lock);
-	if (device->request_queue == NULL)
+	block->request_queue = blk_init_queue(do_dasd_request,
+					       &block->request_queue_lock);
+	if (block->request_queue == NULL)
 		return -ENOMEM;
 
-	device->request_queue->queuedata = device;
+	block->request_queue->queuedata = block;
 
-	elevator_exit(device->request_queue->elevator);
-	rc = elevator_init(device->request_queue, "deadline");
+	elevator_exit(block->request_queue->elevator);
+	rc = elevator_init(block->request_queue, "deadline");
 	if (rc) {
-		blk_cleanup_queue(device->request_queue);
+		blk_cleanup_queue(block->request_queue);
 		return rc;
 	}
 	return 0;
@@ -1780,79 +1970,76 @@ dasd_alloc_queue(struct dasd_device * device)
 /*
  * Allocate and initialize request queue.
  */
-static void
-dasd_setup_queue(struct dasd_device * device)
+static void dasd_setup_queue(struct dasd_block *block)
 {
 	int max;
 
-	blk_queue_hardsect_size(device->request_queue, device->bp_block);
-	max = device->discipline->max_blocks << device->s2b_shift;
-	blk_queue_max_sectors(device->request_queue, max);
-	blk_queue_max_phys_segments(device->request_queue, -1L);
-	blk_queue_max_hw_segments(device->request_queue, -1L);
-	blk_queue_max_segment_size(device->request_queue, -1L);
-	blk_queue_segment_boundary(device->request_queue, -1L);
-	blk_queue_ordered(device->request_queue, QUEUE_ORDERED_TAG, NULL);
+	blk_queue_hardsect_size(block->request_queue, block->bp_block);
+	max = block->base->discipline->max_blocks << block->s2b_shift;
+	blk_queue_max_sectors(block->request_queue, max);
+	blk_queue_max_phys_segments(block->request_queue, -1L);
+	blk_queue_max_hw_segments(block->request_queue, -1L);
+	blk_queue_max_segment_size(block->request_queue, -1L);
+	blk_queue_segment_boundary(block->request_queue, -1L);
+	blk_queue_ordered(block->request_queue, QUEUE_ORDERED_DRAIN, NULL);
 }
 
 /*
  * Deactivate and free request queue.
  */
-static void
-dasd_free_queue(struct dasd_device * device)
+static void dasd_free_queue(struct dasd_block *block)
 {
-	if (device->request_queue) {
-		blk_cleanup_queue(device->request_queue);
-		device->request_queue = NULL;
+	if (block->request_queue) {
+		blk_cleanup_queue(block->request_queue);
+		block->request_queue = NULL;
 	}
 }
 
 /*
  * Flush request on the request queue.
  */
-static void
-dasd_flush_request_queue(struct dasd_device * device)
+static void dasd_flush_request_queue(struct dasd_block *block)
 {
 	struct request *req;
 
-	if (!device->request_queue)
+	if (!block->request_queue)
 		return;
 
-	spin_lock_irq(&device->request_queue_lock);
-	while ((req = elv_next_request(device->request_queue))) {
+	spin_lock_irq(&block->request_queue_lock);
+	while ((req = elv_next_request(block->request_queue))) {
 		blkdev_dequeue_request(req);
 		dasd_end_request(req, 0);
 	}
-	spin_unlock_irq(&device->request_queue_lock);
+	spin_unlock_irq(&block->request_queue_lock);
 }
 
-static int
-dasd_open(struct inode *inp, struct file *filp)
+static int dasd_open(struct inode *inp, struct file *filp)
 {
 	struct gendisk *disk = inp->i_bdev->bd_disk;
-	struct dasd_device *device = disk->private_data;
+	struct dasd_block *block = disk->private_data;
+	struct dasd_device *base = block->base;
 	int rc;
 
-        atomic_inc(&device->open_count);
-	if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {
+	atomic_inc(&block->open_count);
+	if (test_bit(DASD_FLAG_OFFLINE, &base->flags)) {
 		rc = -ENODEV;
 		goto unlock;
 	}
 
-	if (!try_module_get(device->discipline->owner)) {
+	if (!try_module_get(base->discipline->owner)) {
 		rc = -EINVAL;
 		goto unlock;
 	}
 
 	if (dasd_probeonly) {
-		DEV_MESSAGE(KERN_INFO, device, "%s",
+		DEV_MESSAGE(KERN_INFO, base, "%s",
 			    "No access to device due to probeonly mode");
 		rc = -EPERM;
 		goto out;
 	}
 
-	if (device->state <= DASD_STATE_BASIC) {
-		DBF_DEV_EVENT(DBF_ERR, device, " %s",
+	if (base->state <= DASD_STATE_BASIC) {
+		DBF_DEV_EVENT(DBF_ERR, base, " %s",
 			      " Cannot open unrecognized device");
 		rc = -ENODEV;
 		goto out;
@@ -1861,41 +2048,41 @@ dasd_open(struct inode *inp, struct file *filp)
 	return 0;
 
 out:
-	module_put(device->discipline->owner);
+	module_put(base->discipline->owner);
 unlock:
-	atomic_dec(&device->open_count);
+	atomic_dec(&block->open_count);
 	return rc;
 }
 
-static int
-dasd_release(struct inode *inp, struct file *filp)
+static int dasd_release(struct inode *inp, struct file *filp)
 {
 	struct gendisk *disk = inp->i_bdev->bd_disk;
-	struct dasd_device *device = disk->private_data;
+	struct dasd_block *block = disk->private_data;
 
-	atomic_dec(&device->open_count);
-	module_put(device->discipline->owner);
+	atomic_dec(&block->open_count);
+	module_put(block->base->discipline->owner);
 	return 0;
 }
 
 /*
  * Return disk geometry.
  */
-static int
-dasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
+static int dasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
-	struct dasd_device *device;
+	struct dasd_block *block;
+	struct dasd_device *base;
 
-	device = bdev->bd_disk->private_data;
-	if (!device)
+	block = bdev->bd_disk->private_data;
+	base = block->base;
+	if (!block)
 		return -ENODEV;
 
-	if (!device->discipline ||
-	    !device->discipline->fill_geometry)
+	if (!base->discipline ||
+	    !base->discipline->fill_geometry)
 		return -EINVAL;
 
-	device->discipline->fill_geometry(device, geo);
-	geo->start = get_start_sect(bdev) >> device->s2b_shift;
+	base->discipline->fill_geometry(block, geo);
+	geo->start = get_start_sect(bdev) >> block->s2b_shift;
 	return 0;
 }
 
@@ -1909,6 +2096,9 @@ dasd_device_operations = {
 	.getgeo		= dasd_getgeo,
 };
 
+/*******************************************************************************
+ * end of block device operations
+ */
 
 static void
 dasd_exit(void)
@@ -1937,9 +2127,8 @@ dasd_exit(void)
  * Initial attempt at a probe function. this can be simplified once
  * the other detection code is gone.
  */
-int
-dasd_generic_probe (struct ccw_device *cdev,
-		    struct dasd_discipline *discipline)
+int dasd_generic_probe(struct ccw_device *cdev,
+		       struct dasd_discipline *discipline)
 {
 	int ret;
 
@@ -1979,10 +2168,10 @@ dasd_generic_probe (struct ccw_device *cdev,
  * This will one day be called from a global not_oper handler.
  * It is also used by driver_unregister during module unload.
  */
-void
-dasd_generic_remove (struct ccw_device *cdev)
+void dasd_generic_remove(struct ccw_device *cdev)
 {
 	struct dasd_device *device;
+	struct dasd_block *block;
 
 	cdev->handler = NULL;
 
@@ -2002,7 +2191,15 @@ dasd_generic_remove (struct ccw_device *cdev)
 	 */
 	dasd_set_target_state(device, DASD_STATE_NEW);
 	/* dasd_delete_device destroys the device reference. */
+	block = device->block;
+	device->block = NULL;
 	dasd_delete_device(device);
+	/*
+	 * life cycle of block is bound to device, so delete it after
+	 * device was safely removed
+	 */
+	if (block)
+		dasd_free_block(block);
 }
 
 /*
@@ -2010,10 +2207,8 @@ dasd_generic_remove (struct ccw_device *cdev)
  * the device is detected for the first time and is supposed to be used
  * or the user has started activation through sysfs.
  */
-int
-dasd_generic_set_online (struct ccw_device *cdev,
-			 struct dasd_discipline *base_discipline)
-
+int dasd_generic_set_online(struct ccw_device *cdev,
+			    struct dasd_discipline *base_discipline)
 {
 	struct dasd_discipline *discipline;
 	struct dasd_device *device;
@@ -2049,6 +2244,7 @@ dasd_generic_set_online (struct ccw_device *cdev,
 	device->base_discipline = base_discipline;
 	device->discipline = discipline;
 
+	/* check_device will allocate block device if necessary */
 	rc = discipline->check_device(device);
 	if (rc) {
 		printk (KERN_WARNING
@@ -2068,6 +2264,8 @@ dasd_generic_set_online (struct ccw_device *cdev,
 			cdev->dev.bus_id);
 		rc = -ENODEV;
 		dasd_set_target_state(device, DASD_STATE_NEW);
+		if (device->block)
+			dasd_free_block(device->block);
 		dasd_delete_device(device);
 	} else
 		pr_debug("dasd_generic device %s found\n",
@@ -2082,10 +2280,10 @@ dasd_generic_set_online (struct ccw_device *cdev,
 	return rc;
 }
 
-int
-dasd_generic_set_offline (struct ccw_device *cdev)
+int dasd_generic_set_offline(struct ccw_device *cdev)
 {
 	struct dasd_device *device;
+	struct dasd_block *block;
 	int max_count, open_count;
 
 	device = dasd_device_from_cdev(cdev);
@@ -2102,30 +2300,39 @@ dasd_generic_set_offline (struct ccw_device *cdev)
 	 * the blkdev_get in dasd_scan_partitions. We are only interested
 	 * in the other openers.
 	 */
-	max_count = device->bdev ? 0 : -1;
-	open_count = (int) atomic_read(&device->open_count);
-	if (open_count > max_count) {
-		if (open_count > 0)
-			printk (KERN_WARNING "Can't offline dasd device with "
-				"open count = %i.\n",
-				open_count);
-		else
-			printk (KERN_WARNING "%s",
-				"Can't offline dasd device due to internal "
-				"use\n");
-		clear_bit(DASD_FLAG_OFFLINE, &device->flags);
-		dasd_put_device(device);
-		return -EBUSY;
+	if (device->block) {
+		struct dasd_block *block = device->block;
+		max_count = block->bdev ? 0 : -1;
+		open_count = (int) atomic_read(&block->open_count);
+		if (open_count > max_count) {
+			if (open_count > 0)
+				printk(KERN_WARNING "Can't offline dasd "
+				       "device with open count = %i.\n",
+				       open_count);
+			else
+				printk(KERN_WARNING "%s",
+				       "Can't offline dasd device due "
+				       "to internal use\n");
+			clear_bit(DASD_FLAG_OFFLINE, &device->flags);
+			dasd_put_device(device);
+			return -EBUSY;
+		}
 	}
 	dasd_set_target_state(device, DASD_STATE_NEW);
 	/* dasd_delete_device destroys the device reference. */
+	block = device->block;
+	device->block = NULL;
 	dasd_delete_device(device);
-
+	/*
+	 * life cycle of block is bound to device, so delete it after
+	 * device was safely removed
+	 */
+	if (block)
+		dasd_free_block(block);
 	return 0;
 }
 
-int
-dasd_generic_notify(struct ccw_device *cdev, int event)
+int dasd_generic_notify(struct ccw_device *cdev, int event)
 {
 	struct dasd_device *device;
 	struct dasd_ccw_req *cqr;
@@ -2146,27 +2353,22 @@ dasd_generic_notify(struct ccw_device *cdev, int event)
 		if (device->state < DASD_STATE_BASIC)
 			break;
 		/* Device is active. We want to keep it. */
-		if (test_bit(DASD_FLAG_DSC_ERROR, &device->flags)) {
-			list_for_each_entry(cqr, &device->ccw_queue, list)
-				if (cqr->status == DASD_CQR_IN_IO)
-					cqr->status = DASD_CQR_FAILED;
-			device->stopped |= DASD_STOPPED_DC_EIO;
-		} else {
-			list_for_each_entry(cqr, &device->ccw_queue, list)
-				if (cqr->status == DASD_CQR_IN_IO) {
-					cqr->status = DASD_CQR_QUEUED;
-					cqr->retries++;
-				}
-			device->stopped |= DASD_STOPPED_DC_WAIT;
-			dasd_set_timer(device, 0);
-		}
-		dasd_schedule_bh(device);
+		list_for_each_entry(cqr, &device->ccw_queue, devlist)
+			if (cqr->status == DASD_CQR_IN_IO) {
+				cqr->status = DASD_CQR_QUEUED;
+				cqr->retries++;
+			}
+		device->stopped |= 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_STOPPED_DC_EIO);
-		dasd_schedule_bh(device);
+		device->stopped &= ~DASD_STOPPED_DC_WAIT;
+		dasd_schedule_device_bh(device);
+		if (device->block)
+			dasd_schedule_block_bh(device->block);
 		ret = 1;
 		break;
 	}
@@ -2196,7 +2398,8 @@ static struct dasd_ccw_req *dasd_generic_build_rdc(struct dasd_device *device,
 	ccw->cda = (__u32)(addr_t)rdc_buffer;
 	ccw->count = rdc_buffer_size;
 
-	cqr->device = device;
+	cqr->startdev = device;
+	cqr->memdev = device;
 	cqr->expires = 10*HZ;
 	clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 	cqr->retries = 2;
@@ -2218,13 +2421,12 @@ int dasd_generic_read_dev_chars(struct dasd_device *device, char *magic,
 		return PTR_ERR(cqr);
 
 	ret = dasd_sleep_on(cqr);
-	dasd_sfree_request(cqr, cqr->device);
+	dasd_sfree_request(cqr, cqr->memdev);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(dasd_generic_read_dev_chars);
 
-static int __init
-dasd_init(void)
+static int __init dasd_init(void)
 {
 	int rc;
 
@@ -2232,7 +2434,7 @@ dasd_init(void)
 	init_waitqueue_head(&dasd_flush_wq);
 
 	/* register 'common' DASD debug area, used for all DBF_XXX calls */
-	dasd_debug_area = debug_register("dasd", 1, 2, 8 * sizeof (long));
+	dasd_debug_area = debug_register("dasd", 1, 2, 8 * sizeof(long));
 	if (dasd_debug_area == NULL) {
 		rc = -ENOMEM;
 		goto failed;
@@ -2278,15 +2480,18 @@ EXPORT_SYMBOL(dasd_diag_discipline_pointer);
 EXPORT_SYMBOL(dasd_add_request_head);
 EXPORT_SYMBOL(dasd_add_request_tail);
 EXPORT_SYMBOL(dasd_cancel_req);
-EXPORT_SYMBOL(dasd_clear_timer);
+EXPORT_SYMBOL(dasd_device_clear_timer);
+EXPORT_SYMBOL(dasd_block_clear_timer);
 EXPORT_SYMBOL(dasd_enable_device);
 EXPORT_SYMBOL(dasd_int_handler);
 EXPORT_SYMBOL(dasd_kfree_request);
 EXPORT_SYMBOL(dasd_kick_device);
 EXPORT_SYMBOL(dasd_kmalloc_request);
-EXPORT_SYMBOL(dasd_schedule_bh);
+EXPORT_SYMBOL(dasd_schedule_device_bh);
+EXPORT_SYMBOL(dasd_schedule_block_bh);
 EXPORT_SYMBOL(dasd_set_target_state);
-EXPORT_SYMBOL(dasd_set_timer);
+EXPORT_SYMBOL(dasd_device_set_timer);
+EXPORT_SYMBOL(dasd_block_set_timer);
 EXPORT_SYMBOL(dasd_sfree_request);
 EXPORT_SYMBOL(dasd_sleep_on);
 EXPORT_SYMBOL(dasd_sleep_on_immediatly);
@@ -2300,4 +2505,7 @@ EXPORT_SYMBOL_GPL(dasd_generic_remove);
 EXPORT_SYMBOL_GPL(dasd_generic_notify);
 EXPORT_SYMBOL_GPL(dasd_generic_set_online);
 EXPORT_SYMBOL_GPL(dasd_generic_set_offline);
-
+EXPORT_SYMBOL_GPL(dasd_generic_handle_state_change);
+EXPORT_SYMBOL_GPL(dasd_flush_device_queue);
+EXPORT_SYMBOL_GPL(dasd_alloc_block);
+EXPORT_SYMBOL_GPL(dasd_free_block);