dasd.c

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/*
 * Author(s)......: Holger Smolinski <[email protected]>
 *          Horst Hummel <[email protected]>
 *          Carsten Otte <[email protected]>
 *          Martin Schwidefsky <[email protected]>
 * Bugreports.to..: <[email protected]>
 * Copyright IBM Corp. 1999, 2009
 */

#define KMSG_COMPONENT "dasd"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ctype.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/hdreg.h>
#include <linux/async.h>
#include <linux/mutex.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>

#include <asm/ccwdev.h>
#include <asm/ebcdic.h>
#include <asm/idals.h>
#include <asm/itcw.h>
#include <asm/diag.h>

/* This is ugly... */
#define PRINTK_HEADER "dasd:"

#include "dasd_int.h"
/*
 * SECTION: Constant definitions to be used within this file
 */
#define DASD_CHANQ_MAX_SIZE 4

#define DASD_SLEEPON_START_TAG  (void *) 1
#define DASD_SLEEPON_END_TAG    (void *) 2

/*
 * SECTION: exported variables of dasd.c
 */
debug_info_t *dasd_debug_area;
static struct dentry *dasd_debugfs_root_entry;
struct dasd_discipline *dasd_diag_discipline_pointer;
void dasd_int_handler(struct ccw_device *, unsigned long, struct irb *);

MODULE_AUTHOR("Holger Smolinski <[email protected]>");
MODULE_DESCRIPTION("Linux on S/390 DASD device driver,"
           " Copyright IBM Corp. 2000");
MODULE_SUPPORTED_DEVICE("dasd");
MODULE_LICENSE("GPL");

/*
 * SECTION: prototypes for static functions of dasd.c
 */
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 do_restore_device(struct work_struct *);
static void do_reload_device(struct work_struct *);
static void dasd_return_cqr_cb(struct dasd_ccw_req *, void *);
static void dasd_device_timeout(unsigned long);
static void dasd_block_timeout(unsigned long);
static void __dasd_process_erp(struct dasd_device *, struct dasd_ccw_req *);
static void dasd_profile_init(struct dasd_profile *, struct dentry *);
static void dasd_profile_exit(struct dasd_profile *);

/*
 * SECTION: Operations on the device structure.
 */
static wait_queue_head_t dasd_init_waitq;
static wait_queue_head_t dasd_flush_wq;
static wait_queue_head_t generic_waitq;
static wait_queue_head_t shutdown_waitq;

/*
 * Allocate memory for a new device structure.
 */
struct dasd_device *dasd_alloc_device(void)
{
    struct dasd_device *device;

    device = kzalloc(sizeof(struct dasd_device), GFP_ATOMIC);
    if (!device)
        return ERR_PTR(-ENOMEM);

    /* Get two pages for normal block device operations. */
    device->ccw_mem = (void *) __get_free_pages(GFP_ATOMIC | GFP_DMA, 1);
    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) {
        free_pages((unsigned long) device->ccw_mem, 1);
        kfree(device);
        return ERR_PTR(-ENOMEM);
    }

    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);
    atomic_set(&device->tasklet_scheduled, 0);
    tasklet_init(&device->tasklet,
             (void (*)(unsigned long)) dasd_device_tasklet,
             (unsigned long) device);
    INIT_LIST_HEAD(&device->ccw_queue);
    init_timer(&device->timer);
    device->timer.function = dasd_device_timeout;
    device->timer.data = (unsigned long) device;
    INIT_WORK(&device->kick_work, do_kick_device);
    INIT_WORK(&device->restore_device, do_restore_device);
    INIT_WORK(&device->reload_device, do_reload_device);
    device->state = DASD_STATE_NEW;
    device->target = DASD_STATE_NEW;
    mutex_init(&device->state_mutex);
    spin_lock_init(&device->profile.lock);
    return device;
}

/*
 * Free memory of a device structure.
 */
void dasd_free_device(struct dasd_device *device)
{
    kfree(device->private);
    free_page((unsigned long) device->erp_mem);
    free_pages((unsigned long) device->ccw_mem, 1);
    kfree(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);
    block->timer.function = dasd_block_timeout;
    block->timer.data = (unsigned long) block;
    spin_lock_init(&block->profile.lock);

    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)
{
    int rc;

    /*
     * As long as the device is not in state DASD_STATE_NEW we want to
     * keep the reference count > 0.
     */
    dasd_get_device(device);

    if (device->block) {
        rc = dasd_alloc_queue(device->block);
        if (rc) {
            dasd_put_device(device);
            return rc;
        }
    }
    device->state = DASD_STATE_KNOWN;
    return 0;
}

/*
 * Let the system forget about a 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->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;

    if (device->block)
        dasd_free_queue(device->block);

    /* Give up reference we took in dasd_state_new_to_known. */
    dasd_put_device(device);
    return 0;
}

static struct dentry *dasd_debugfs_setup(const char *name,
                     struct dentry *base_dentry)
{
    struct dentry *pde;

    if (!base_dentry)
        return NULL;
    pde = debugfs_create_dir(name, base_dentry);
    if (!pde || IS_ERR(pde))
        return NULL;
    return pde;
}

/*
 * Request the irq line for the device.
 */
static int dasd_state_known_to_basic(struct dasd_device *device)
{
    struct dasd_block *block = device->block;
    int rc;

    /* Allocate and register gendisk structure. */
    if (block) {
        rc = dasd_gendisk_alloc(block);
        if (rc)
            return rc;
        block->debugfs_dentry =
            dasd_debugfs_setup(block->gdp->disk_name,
                       dasd_debugfs_root_entry);
        dasd_profile_init(&block->profile, block->debugfs_dentry);
        if (dasd_global_profile_level == DASD_PROFILE_ON)
            dasd_profile_on(&device->block->profile);
    }
    device->debugfs_dentry =
        dasd_debugfs_setup(dev_name(&device->cdev->dev),
                   dasd_debugfs_root_entry);
    dasd_profile_init(&device->profile, device->debugfs_dentry);

    /* register 'device' debug area, used for all DBF_DEV_XXX calls */
    device->debug_area = debug_register(dev_name(&device->cdev->dev), 4, 1,
                        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");

    device->state = DASD_STATE_BASIC;
    return 0;
}

/*
 * Release the irq line for the device. Terminate any running i/o.
 */
static int dasd_state_basic_to_known(struct dasd_device *device)
{
    int rc;
    if (device->block) {
        dasd_profile_exit(&device->block->profile);
        if (device->block->debugfs_dentry)
            debugfs_remove(device->block->debugfs_dentry);
        dasd_gendisk_free(device->block);
        dasd_block_clear_timer(device->block);
    }
    rc = dasd_flush_device_queue(device);
    if (rc)
        return rc;
    dasd_device_clear_timer(device);
    dasd_profile_exit(&device->profile);
    if (device->debugfs_dentry)
        debugfs_remove(device->debugfs_dentry);

    DBF_DEV_EVENT(DBF_EMERG, device, "%p debug area deleted", device);
    if (device->debug_area != NULL) {
        debug_unregister(device->debug_area);
        device->debug_area = NULL;
    }
    device->state = DASD_STATE_KNOWN;
    return 0;
}

/*
 * Do the initial analysis. The do_analysis function may return
 * -EAGAIN in which case the device keeps the state DASD_STATE_BASIC
 * until the discipline decides to continue the startup sequence
 * by calling the function dasd_change_state. The eckd disciplines
 * uses this to start a ccw that detects the format. The completion
 * interrupt for this detection ccw uses the kernel event daemon to
 * trigger the call to dasd_change_state. All this is done in the
 * discipline code, see dasd_eckd.c.
 * After the analysis ccw is done (do_analysis returned 0) the block
 * device is setup.
 * 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)
{
    int rc;
    struct dasd_block *block;

    rc = 0;
    block = device->block;
    /* make disk known with correct capacity */
    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;
}

/*
 * Remove device from block device layer. Destroy dirty buffers.
 * 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)
{
    int rc;

    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_flush_request_queue(block);
        dasd_destroy_partitions(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)
{
    device->state = DASD_STATE_BASIC;
    return 0;
}

/*
 * Make the device online and schedule the bottom half to start
 * the requeueing of requests from the linux request queue to the
 * ccw queue.
 */
static int
dasd_state_ready_to_online(struct dasd_device * device)
{
    int rc;
    struct gendisk *disk;
    struct disk_part_iter piter;
    struct hd_struct *part;

    if (device->discipline->ready_to_online) {
        rc = device->discipline->ready_to_online(device);
        if (rc)
            return rc;
    }
    device->state = DASD_STATE_ONLINE;
    if (device->block) {
        dasd_schedule_block_bh(device->block);
        if ((device->features & DASD_FEATURE_USERAW)) {
            disk = device->block->gdp;
            kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
            return 0;
        }
        disk = device->block->bdev->bd_disk;
        disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
        while ((part = disk_part_iter_next(&piter)))
            kobject_uevent(&part_to_dev(part)->kobj, KOBJ_CHANGE);
        disk_part_iter_exit(&piter);
    }
    return 0;
}

/*
 * Stop the requeueing of requests again.
 */
static int dasd_state_online_to_ready(struct dasd_device *device)
{
    int rc;
    struct gendisk *disk;
    struct disk_part_iter piter;
    struct hd_struct *part;

    if (device->discipline->online_to_ready) {
        rc = device->discipline->online_to_ready(device);
        if (rc)
            return rc;
    }
    device->state = DASD_STATE_READY;
    if (device->block && !(device->features & DASD_FEATURE_USERAW)) {
        disk = device->block->bdev->bd_disk;
        disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
        while ((part = disk_part_iter_next(&piter)))
            kobject_uevent(&part_to_dev(part)->kobj, KOBJ_CHANGE);
        disk_part_iter_exit(&piter);
    }
    return 0;
}

/*
 * Device startup state changes.
 */
static int dasd_increase_state(struct dasd_device *device)
{
    int rc;

    rc = 0;
    if (device->state == DASD_STATE_NEW &&
        device->target >= DASD_STATE_KNOWN)
        rc = dasd_state_new_to_known(device);

    if (!rc &&
        device->state == DASD_STATE_KNOWN &&
        device->target >= DASD_STATE_BASIC)
        rc = dasd_state_known_to_basic(device);

    if (!rc &&
        device->state == DASD_STATE_BASIC &&
        device->target >= DASD_STATE_READY)
        rc = dasd_state_basic_to_ready(device);

    if (!rc &&
        device->state == DASD_STATE_UNFMT &&
        device->target > DASD_STATE_UNFMT)
        rc = -EPERM;

    if (!rc &&
        device->state == DASD_STATE_READY &&
        device->target >= DASD_STATE_ONLINE)
        rc = dasd_state_ready_to_online(device);

    return rc;
}

/*
 * Device shutdown state changes.
 */
static int dasd_decrease_state(struct dasd_device *device)
{
    int rc;

    rc = 0;
    if (device->state == DASD_STATE_ONLINE &&
        device->target <= DASD_STATE_READY)
        rc = dasd_state_online_to_ready(device);

    if (!rc &&
        device->state == DASD_STATE_READY &&
        device->target <= DASD_STATE_BASIC)
        rc = dasd_state_ready_to_basic(device);

    if (!rc &&
        device->state == DASD_STATE_UNFMT &&
        device->target <= DASD_STATE_BASIC)
        rc = dasd_state_unfmt_to_basic(device);

    if (!rc &&
        device->state == DASD_STATE_BASIC &&
        device->target <= DASD_STATE_KNOWN)
        rc = dasd_state_basic_to_known(device);

    if (!rc &&
        device->state == DASD_STATE_KNOWN &&
        device->target <= DASD_STATE_NEW)
        rc = dasd_state_known_to_new(device);

    return rc;
}

/*
 * This is the main startup/shutdown routine.
 */
static void dasd_change_state(struct dasd_device *device)
{
    int rc;

    if (device->state == device->target)
        /* Already where we want to go today... */
        return;
    if (device->state < device->target)
        rc = dasd_increase_state(device);
    else
        rc = dasd_decrease_state(device);
    if (rc == -EAGAIN)
        return;
    if (rc)
        device->target = device->state;

    /* let user-space know that the device status changed */
    kobject_uevent(&device->cdev->dev.kobj, KOBJ_CHANGE);

    if (device->state == device->target)
        wake_up(&dasd_init_waitq);
}

/*
 * Kick starter for devices that did not complete the startup/shutdown
 * procedure or were sleeping because of a pending state.
 * 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)
{
    struct dasd_device *device = container_of(work, struct dasd_device, kick_work);
    mutex_lock(&device->state_mutex);
    dasd_change_state(device);
    mutex_unlock(&device->state_mutex);
    dasd_schedule_device_bh(device);
    dasd_put_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. */
    schedule_work(&device->kick_work);
}

/*
 * dasd_reload_device will schedule a call do do_reload_device to the kernel
 * event daemon.
 */
static void do_reload_device(struct work_struct *work)
{
    struct dasd_device *device = container_of(work, struct dasd_device,
                          reload_device);
    device->discipline->reload(device);
    dasd_put_device(device);
}

void dasd_reload_device(struct dasd_device *device)
{
    dasd_get_device(device);
    /* queue call to dasd_reload_device to the kernel event daemon. */
    schedule_work(&device->reload_device);
}
EXPORT_SYMBOL(dasd_reload_device);

/*
 * dasd_restore_device will schedule a call do do_restore_device to the kernel
 * event daemon.
 */
static void do_restore_device(struct work_struct *work)
{
    struct dasd_device *device = container_of(work, struct dasd_device,
                          restore_device);
    device->cdev->drv->restore(device->cdev);
    dasd_put_device(device);
}

void dasd_restore_device(struct dasd_device *device)
{
    dasd_get_device(device);
    /* queue call to dasd_restore_device to the kernel event daemon. */
    schedule_work(&device->restore_device);
}

/*
 * Set the target state for a device and starts the state change.
 */
void dasd_set_target_state(struct dasd_device *device, int target)
{
    dasd_get_device(device);
    mutex_lock(&device->state_mutex);
    /* If we are in probeonly mode stop at DASD_STATE_READY. */
    if (dasd_probeonly && target > DASD_STATE_READY)
        target = DASD_STATE_READY;
    if (device->target != target) {
        if (device->state == target)
            wake_up(&dasd_init_waitq);
        device->target = target;
    }
    if (device->state != device->target)
        dasd_change_state(device);
    mutex_unlock(&device->state_mutex);
    dasd_put_device(device);
}

/*
 * Enable devices with device numbers in [from..to].
 */
static inline int _wait_for_device(struct dasd_device *device)
{
    return (device->state == device->target);
}

void dasd_enable_device(struct dasd_device *device)
{
    dasd_set_target_state(device, DASD_STATE_ONLINE);
    if (device->state <= DASD_STATE_KNOWN)
        /* No discipline for device found. */
        dasd_set_target_state(device, DASD_STATE_NEW);
    /* Now wait for the devices to come up. */
    wait_event(dasd_init_waitq, _wait_for_device(device));

    dasd_reload_device(device);
    if (device->discipline->kick_validate)
        device->discipline->kick_validate(device);
}

/*
 * SECTION: device operation (interrupt handler, start i/o, term i/o ...)
 */

unsigned int dasd_global_profile_level = DASD_PROFILE_OFF;

#ifdef CONFIG_DASD_PROFILE
struct dasd_profile_info dasd_global_profile_data;
static struct dentry *dasd_global_profile_dentry;
static struct dentry *dasd_debugfs_global_entry;

/*
 * Add profiling information for cqr before execution.
 */
static void dasd_profile_start(struct dasd_block *block,
                   struct dasd_ccw_req *cqr,
                   struct request *req)
{
    struct list_head *l;
    unsigned int counter;
    struct dasd_device *device;

    /* count the length of the chanq for statistics */
    counter = 0;
    if (dasd_global_profile_level || block->profile.data)
        list_for_each(l, &block->ccw_queue)
            if (++counter >= 31)
                break;

    if (dasd_global_profile_level) {
        dasd_global_profile_data.dasd_io_nr_req[counter]++;
        if (rq_data_dir(req) == READ)
            dasd_global_profile_data.dasd_read_nr_req[counter]++;
    }

    spin_lock(&block->profile.lock);
    if (block->profile.data)
        block->profile.data->dasd_io_nr_req[counter]++;
        if (rq_data_dir(req) == READ)
            block->profile.data->dasd_read_nr_req[counter]++;
    spin_unlock(&block->profile.lock);

    /*
     * We count the request for the start device, even though it may run on
     * some other device due to error recovery. This way we make sure that
     * we count each request only once.
     */
    device = cqr->startdev;
    if (device->profile.data) {
        counter = 1; /* request is not yet queued on the start device */
        list_for_each(l, &device->ccw_queue)
            if (++counter >= 31)
                break;
    }
    spin_lock(&device->profile.lock);
    if (device->profile.data) {
        device->profile.data->dasd_io_nr_req[counter]++;
        if (rq_data_dir(req) == READ)
            device->profile.data->dasd_read_nr_req[counter]++;
    }
    spin_unlock(&device->profile.lock);
}

/*
 * Add profiling information for cqr after execution.
 */

#define dasd_profile_counter(value, index)             \
{                                  \
    for (index = 0; index < 31 && value >> (2+index); index++) \
        ;                          \
}

static void dasd_profile_end_add_data(struct dasd_profile_info *data,
                      int is_alias,
                      int is_tpm,
                      int is_read,
                      long sectors,
                      int sectors_ind,
                      int tottime_ind,
                      int tottimeps_ind,
                      int strtime_ind,
                      int irqtime_ind,
                      int irqtimeps_ind,
                      int endtime_ind)
{
    /* in case of an overflow, reset the whole profile */
    if (data->dasd_io_reqs == UINT_MAX) {
            memset(data, 0, sizeof(*data));
            getnstimeofday(&data->starttod);
    }
    data->dasd_io_reqs++;
    data->dasd_io_sects += sectors;
    if (is_alias)
        data->dasd_io_alias++;
    if (is_tpm)
        data->dasd_io_tpm++;

    data->dasd_io_secs[sectors_ind]++;
    data->dasd_io_times[tottime_ind]++;
    data->dasd_io_timps[tottimeps_ind]++;
    data->dasd_io_time1[strtime_ind]++;
    data->dasd_io_time2[irqtime_ind]++;
    data->dasd_io_time2ps[irqtimeps_ind]++;
    data->dasd_io_time3[endtime_ind]++;

    if (is_read) {
        data->dasd_read_reqs++;
        data->dasd_read_sects += sectors;
        if (is_alias)
            data->dasd_read_alias++;
        if (is_tpm)
            data->dasd_read_tpm++;
        data->dasd_read_secs[sectors_ind]++;
        data->dasd_read_times[tottime_ind]++;
        data->dasd_read_time1[strtime_ind]++;
        data->dasd_read_time2[irqtime_ind]++;
        data->dasd_read_time3[endtime_ind]++;
    }
}

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;
    struct dasd_device *device;
    int sectors_ind, tottime_ind, tottimeps_ind, strtime_ind;
    int irqtime_ind, irqtimeps_ind, endtime_ind;

    device = cqr->startdev;
    if (!(dasd_global_profile_level ||
          block->profile.data ||
          device->profile.data))
        return;

    sectors = blk_rq_sectors(req);
    if (!cqr->buildclk || !cqr->startclk ||
        !cqr->stopclk || !cqr->endclk ||
        !sectors)
        return;

    strtime = ((cqr->startclk - cqr->buildclk) >> 12);
    irqtime = ((cqr->stopclk - cqr->startclk) >> 12);
    endtime = ((cqr->endclk - cqr->stopclk) >> 12);
    tottime = ((cqr->endclk - cqr->buildclk) >> 12);
    tottimeps = tottime / sectors;

    dasd_profile_counter(sectors, sectors_ind);
    dasd_profile_counter(tottime, tottime_ind);
    dasd_profile_counter(tottimeps, tottimeps_ind);
    dasd_profile_counter(strtime, strtime_ind);
    dasd_profile_counter(irqtime, irqtime_ind);
    dasd_profile_counter(irqtime / sectors, irqtimeps_ind);
    dasd_profile_counter(endtime, endtime_ind);

    if (dasd_global_profile_level) {
        dasd_profile_end_add_data(&dasd_global_profile_data,
                      cqr->startdev != block->base,
                      cqr->cpmode == 1,
                      rq_data_dir(req) == READ,
                      sectors, sectors_ind, tottime_ind,
                      tottimeps_ind, strtime_ind,
                      irqtime_ind, irqtimeps_ind,
                      endtime_ind);
    }

    spin_lock(&block->profile.lock);
    if (block->profile.data)
        dasd_profile_end_add_data(block->profile.data,
                      cqr->startdev != block->base,
                      cqr->cpmode == 1,
                      rq_data_dir(req) == READ,
                      sectors, sectors_ind, tottime_ind,
                      tottimeps_ind, strtime_ind,
                      irqtime_ind, irqtimeps_ind,
                      endtime_ind);
    spin_unlock(&block->profile.lock);

    spin_lock(&device->profile.lock);
    if (device->profile.data)
        dasd_profile_end_add_data(device->profile.data,
                      cqr->startdev != block->base,
                      cqr->cpmode == 1,
                      rq_data_dir(req) == READ,
                      sectors, sectors_ind, tottime_ind,
                      tottimeps_ind, strtime_ind,
                      irqtime_ind, irqtimeps_ind,
                      endtime_ind);
    spin_unlock(&device->profile.lock);
}

void dasd_profile_reset(struct dasd_profile *profile)
{
    struct dasd_profile_info *data;

    spin_lock_bh(&profile->lock);
    data = profile->data;
    if (!data) {
        spin_unlock_bh(&profile->lock);
        return;
    }
    memset(data, 0, sizeof(*data));
    getnstimeofday(&data->starttod);
    spin_unlock_bh(&profile->lock);
}

void dasd_global_profile_reset(void)
{
    memset(&dasd_global_profile_data, 0, sizeof(dasd_global_profile_data));
    getnstimeofday(&dasd_global_profile_data.starttod);
}

int dasd_profile_on(struct dasd_profile *profile)
{
    struct dasd_profile_info *data;

    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (!data)
        return -ENOMEM;
    spin_lock_bh(&profile->lock);
    if (profile->data) {
        spin_unlock_bh(&profile->lock);
        kfree(data);
        return 0;
    }
    getnstimeofday(&data->starttod);
    profile->data = data;
    spin_unlock_bh(&profile->lock);
    return 0;
}

void dasd_profile_off(struct dasd_profile *profile)
{
    spin_lock_bh(&profile->lock);
    kfree(profile->data);
    profile->data = NULL;
    spin_unlock_bh(&profile->lock);
}

char *dasd_get_user_string(const char __user *user_buf, size_t user_len)
{
    char *buffer;

    buffer = vmalloc(user_len + 1);
    if (buffer == NULL)
        return ERR_PTR(-ENOMEM);
    if (copy_from_user(buffer, user_buf, user_len) != 0) {
        vfree(buffer);
        return ERR_PTR(-EFAULT);
    }
    /* got the string, now strip linefeed. */
    if (buffer[user_len - 1] == '\n')
        buffer[user_len - 1] = 0;
    else
        buffer[user_len] = 0;
    return buffer;
}

static ssize_t dasd_stats_write(struct file *file,
                const char __user *user_buf,
                size_t user_len, loff_t *pos)
{
    char *buffer, *str;
    int rc;
    struct seq_file *m = (struct seq_file *)file->private_data;
    struct dasd_profile *prof = m->private;

    if (user_len > 65536)
        user_len = 65536;
    buffer = dasd_get_user_string(user_buf, user_len);
    if (IS_ERR(buffer))
        return PTR_ERR(buffer);

    str = skip_spaces(buffer);
    rc = user_len;
    if (strncmp(str, "reset", 5) == 0) {
        dasd_profile_reset(prof);
    } else if (strncmp(str, "on", 2) == 0) {
        rc = dasd_profile_on(prof);
        if (!rc)
            rc = user_len;
    } else if (strncmp(str, "off", 3) == 0) {
        dasd_profile_off(prof);
    } else
        rc = -EINVAL;
    vfree(buffer);
    return rc;
}

static void dasd_stats_array(struct seq_file *m, unsigned int *array)
{
    int i;

    for (i = 0; i < 32; i++)
        seq_printf(m, "%u ", array[i]);
    seq_putc(m, '\n');
}

static void dasd_stats_seq_print(struct seq_file *m,
                 struct dasd_profile_info *data)
{
    seq_printf(m, "start_time %ld.%09ld\n",
           data->starttod.tv_sec, data->starttod.tv_nsec);
    seq_printf(m, "total_requests %u\n", data->dasd_io_reqs);
    seq_printf(m, "total_sectors %u\n", data->dasd_io_sects);
    seq_printf(m, "total_pav %u\n", data->dasd_io_alias);
    seq_printf(m, "total_hpf %u\n", data->dasd_io_tpm);
    seq_printf(m, "histogram_sectors ");
    dasd_stats_array(m, data->dasd_io_secs);
    seq_printf(m, "histogram_io_times ");
    dasd_stats_array(m, data->dasd_io_times);
    seq_printf(m, "histogram_io_times_weighted ");
    dasd_stats_array(m, data->dasd_io_timps);
    seq_printf(m, "histogram_time_build_to_ssch ");
    dasd_stats_array(m, data->dasd_io_time1);
    seq_printf(m, "histogram_time_ssch_to_irq ");
    dasd_stats_array(m, data->dasd_io_time2);
    seq_printf(m, "histogram_time_ssch_to_irq_weighted ");
    dasd_stats_array(m, data->dasd_io_time2ps);
    seq_printf(m, "histogram_time_irq_to_end ");
    dasd_stats_array(m, data->dasd_io_time3);
    seq_printf(m, "histogram_ccw_queue_length ");
    dasd_stats_array(m, data->dasd_io_nr_req);
    seq_printf(m, "total_read_requests %u\n", data->dasd_read_reqs);
    seq_printf(m, "total_read_sectors %u\n", data->dasd_read_sects);
    seq_printf(m, "total_read_pav %u\n", data->dasd_read_alias);
    seq_printf(m, "total_read_hpf %u\n", data->dasd_read_tpm);
    seq_printf(m, "histogram_read_sectors ");
    dasd_stats_array(m, data->dasd_read_secs);
    seq_printf(m, "histogram_read_times ");
    dasd_stats_array(m, data->dasd_read_times);
    seq_printf(m, "histogram_read_time_build_to_ssch ");
    dasd_stats_array(m, data->dasd_read_time1);
    seq_printf(m, "histogram_read_time_ssch_to_irq ");
    dasd_stats_array(m, data->dasd_read_time2);
    seq_printf(m, "histogram_read_time_irq_to_end ");
    dasd_stats_array(m, data->dasd_read_time3);
    seq_printf(m, "histogram_read_ccw_queue_length ");
    dasd_stats_array(m, data->dasd_read_nr_req);
}

static int dasd_stats_show(struct seq_file *m, void *v)
{
    struct dasd_profile *profile;
    struct dasd_profile_info *data;

    profile = m->private;
    spin_lock_bh(&profile->lock);
    data = profile->data;
    if (!data) {
        spin_unlock_bh(&profile->lock);
        seq_printf(m, "disabled\n");
        return 0;
    }
    dasd_stats_seq_print(m, data);
    spin_unlock_bh(&profile->lock);
    return 0;
}

static int dasd_stats_open(struct inode *inode, struct file *file)
{
    struct dasd_profile *profile = inode->i_private;
    return single_open(file, dasd_stats_show, profile);
}

static const struct file_operations dasd_stats_raw_fops = {
    .owner      = THIS_MODULE,
    .open       = dasd_stats_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
    .write      = dasd_stats_write,
};

static ssize_t dasd_stats_global_write(struct file *file,
                       const char __user *user_buf,
                       size_t user_len, loff_t *pos)
{
    char *buffer, *str;
    ssize_t rc;

    if (user_len > 65536)
        user_len = 65536;
    buffer = dasd_get_user_string(user_buf, user_len);
    if (IS_ERR(buffer))
        return PTR_ERR(buffer);
    str = skip_spaces(buffer);
    rc = user_len;
    if (strncmp(str, "reset", 5) == 0) {
        dasd_global_profile_reset();
    } else if (strncmp(str, "on", 2) == 0) {
        dasd_global_profile_reset();
        dasd_global_profile_level = DASD_PROFILE_GLOBAL_ONLY;
    } else if (strncmp(str, "off", 3) == 0) {
        dasd_global_profile_level = DASD_PROFILE_OFF;
    } else
        rc = -EINVAL;
    vfree(buffer);
    return rc;
}

static int dasd_stats_global_show(struct seq_file *m, void *v)
{
    if (!dasd_global_profile_level) {
        seq_printf(m, "disabled\n");
        return 0;
    }
    dasd_stats_seq_print(m, &dasd_global_profile_data);
    return 0;
}

static int dasd_stats_global_open(struct inode *inode, struct file *file)
{
    return single_open(file, dasd_stats_global_show, NULL);
}

static const struct file_operations dasd_stats_global_fops = {
    .owner      = THIS_MODULE,
    .open       = dasd_stats_global_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
    .write      = dasd_stats_global_write,
};

static void dasd_profile_init(struct dasd_profile *profile,
                  struct dentry *base_dentry)
{
    umode_t mode;
    struct dentry *pde;

    if (!base_dentry)
        return;
    profile->dentry = NULL;
    profile->data = NULL;
    mode = (S_IRUSR | S_IWUSR | S_IFREG);
    pde = debugfs_create_file("statistics", mode, base_dentry,
                  profile, &dasd_stats_raw_fops);
    if (pde && !IS_ERR(pde))
        profile->dentry = pde;
    return;
}

static void dasd_profile_exit(struct dasd_profile *profile)
{
    dasd_profile_off(profile);
    if (profile->dentry) {
        debugfs_remove(profile->dentry);
        profile->dentry = NULL;
    }
}

static void dasd_statistics_removeroot(void)
{
    dasd_global_profile_level = DASD_PROFILE_OFF;
    if (dasd_global_profile_dentry) {
        debugfs_remove(dasd_global_profile_dentry);
        dasd_global_profile_dentry = NULL;
    }
    if (dasd_debugfs_global_entry)
        debugfs_remove(dasd_debugfs_global_entry);
    if (dasd_debugfs_root_entry)
        debugfs_remove(dasd_debugfs_root_entry);
}

static void dasd_statistics_createroot(void)
{
    umode_t mode;
    struct dentry *pde;

    dasd_debugfs_root_entry = NULL;
    dasd_debugfs_global_entry = NULL;
    dasd_global_profile_dentry = NULL;
    pde = debugfs_create_dir("dasd", NULL);
    if (!pde || IS_ERR(pde))
        goto error;
    dasd_debugfs_root_entry = pde;
    pde = debugfs_create_dir("global", dasd_debugfs_root_entry);
    if (!pde || IS_ERR(pde))
        goto error;
    dasd_debugfs_global_entry = pde;

    mode = (S_IRUSR | S_IWUSR | S_IFREG);
    pde = debugfs_create_file("statistics", mode, dasd_debugfs_global_entry,
                  NULL, &dasd_stats_global_fops);
    if (!pde || IS_ERR(pde))
        goto error;
    dasd_global_profile_dentry = pde;
    return;

error:
    DBF_EVENT(DBF_ERR, "%s",
          "Creation of the dasd debugfs interface failed");
    dasd_statistics_removeroot();
    return;
}

#else
#define dasd_profile_start(block, cqr, req) do {} while (0)
#define dasd_profile_end(block, cqr, req) do {} while (0)

static void dasd_statistics_createroot(void)
{
    return;
}

static void dasd_statistics_removeroot(void)
{
    return;
}

int dasd_stats_generic_show(struct seq_file *m, void *v)
{
    seq_printf(m, "Statistics are not activated in this kernel\n");
    return 0;
}

static void dasd_profile_init(struct dasd_profile *profile,
                  struct dentry *base_dentry)
{
    return;
}

static void dasd_profile_exit(struct dasd_profile *profile)
{
    return;
}

int dasd_profile_on(struct dasd_profile *profile)
{
    return 0;
}

#endif              /* CONFIG_DASD_PROFILE */

/*
 * Allocate memory for a channel program with 'cplength' channel
 * command words and 'datasize' additional space. There are two
 * variantes: 1) dasd_kmalloc_request uses kmalloc to get the needed
 * memory and 2) dasd_smalloc_request uses the static ccw memory
 * that gets allocated for each device.
 */
struct dasd_ccw_req *dasd_kmalloc_request(int magic, int cplength,
                      int datasize,
                      struct dasd_device *device)
{
    struct dasd_ccw_req *cqr;

    /* Sanity checks */
    BUG_ON(datasize > PAGE_SIZE ||
         (cplength*sizeof(struct ccw1)) > PAGE_SIZE);

    cqr = kzalloc(sizeof(struct dasd_ccw_req), GFP_ATOMIC);
    if (cqr == NULL)
        return ERR_PTR(-ENOMEM);
    cqr->cpaddr = NULL;
    if (cplength > 0) {
        cqr->cpaddr = kcalloc(cplength, sizeof(struct ccw1),
                      GFP_ATOMIC | GFP_DMA);
        if (cqr->cpaddr == NULL) {
            kfree(cqr);
            return ERR_PTR(-ENOMEM);
        }
    }
    cqr->data = NULL;
    if (datasize > 0) {
        cqr->data = kzalloc(datasize, GFP_ATOMIC | GFP_DMA);
        if (cqr->data == NULL) {
            kfree(cqr->cpaddr);
            kfree(cqr);
            return ERR_PTR(-ENOMEM);
        }
    }
    cqr->magic =  magic;
    set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
    dasd_get_device(device);
    return cqr;
}

struct dasd_ccw_req *dasd_smalloc_request(int magic, int cplength,
                      int datasize,
                      struct dasd_device *device)
{
    unsigned long flags;
    struct dasd_ccw_req *cqr;
    char *data;
    int size;

    size = (sizeof(struct dasd_ccw_req) + 7L) & -8L;
    if (cplength > 0)
        size += cplength * sizeof(struct ccw1);
    if (datasize > 0)
        size += datasize;
    spin_lock_irqsave(&device->mem_lock, flags);
    cqr = (struct dasd_ccw_req *)
        dasd_alloc_chunk(&device->ccw_chunks, size);
    spin_unlock_irqrestore(&device->mem_lock, flags);
    if (cqr == NULL)
        return ERR_PTR(-ENOMEM);
    memset(cqr, 0, sizeof(struct dasd_ccw_req));
    data = (char *) cqr + ((sizeof(struct dasd_ccw_req) + 7L) & -8L);
    cqr->cpaddr = NULL;
    if (cplength > 0) {
        cqr->cpaddr = (struct ccw1 *) data;
        data += cplength*sizeof(struct ccw1);
        memset(cqr->cpaddr, 0, cplength*sizeof(struct ccw1));
    }
    cqr->data = NULL;
    if (datasize > 0) {
        cqr->data = data;
        memset(cqr->data, 0, datasize);
    }
    cqr->magic = magic;
    set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
    dasd_get_device(device);
    return cqr;
}

/*
 * Free memory of a channel program. This function needs to free all the
 * 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)
{
#ifdef CONFIG_64BIT
    struct ccw1 *ccw;

    /* Clear any idals used for the request. */
    ccw = cqr->cpaddr;
    do {
        clear_normalized_cda(ccw);
    } while (ccw++->flags & (CCW_FLAG_CC | CCW_FLAG_DC));
#endif
    kfree(cqr->cpaddr);
    kfree(cqr->data);
    kfree(cqr);
    dasd_put_device(device);
}

void dasd_sfree_request(struct dasd_ccw_req *cqr, struct dasd_device *device)
{
    unsigned long flags;

    spin_lock_irqsave(&device->mem_lock, flags);
    dasd_free_chunk(&device->ccw_chunks, cqr);
    spin_unlock_irqrestore(&device->mem_lock, flags);
    dasd_put_device(device);
}

/*
 * Check discipline magic in cqr.
 */
static inline int dasd_check_cqr(struct dasd_ccw_req *cqr)
{
    struct dasd_device *device;

    if (cqr == NULL)
        return -EINVAL;
    device = cqr->startdev;
    if (strncmp((char *) &cqr->magic, device->discipline->ebcname, 4)) {
        DBF_DEV_EVENT(DBF_WARNING, device,
                " dasd_ccw_req 0x%08x magic doesn't match"
                " discipline 0x%08x",
                cqr->magic,
                *(unsigned int *) device->discipline->name);
        return -EINVAL;
    }
    return 0;
}

/*
 * Terminate the current i/o and set the request to clear_pending.
 * Timer keeps device runnig.
 * ccw_device_clear can fail if the i/o subsystem
 * is in a bad mood.
 */
int dasd_term_IO(struct dasd_ccw_req *cqr)
{
    struct dasd_device *device;
    int retries, rc;
    char errorstring[ERRORLENGTH];

    /* Check the cqr */
    rc = dasd_check_cqr(cqr);
    if (rc)
        return rc;
    retries = 0;
    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->status = DASD_CQR_CLEAR_PENDING;
            cqr->stopclk = get_clock();
            cqr->starttime = 0;
            DBF_DEV_EVENT(DBF_DEBUG, device,
                      "terminate cqr %p successful",
                      cqr);
            break;
        case -ENODEV:
            DBF_DEV_EVENT(DBF_ERR, device, "%s",
                      "device gone, retry");
            break;
        case -EIO:
            DBF_DEV_EVENT(DBF_ERR, device, "%s",
                      "I/O error, retry");
            break;
        case -EINVAL:
        case -EBUSY:
            DBF_DEV_EVENT(DBF_ERR, device, "%s",
                      "device busy, retry later");
            break;
        default:
            /* internal error 10 - unknown rc*/
            snprintf(errorstring, ERRORLENGTH, "10 %d", rc);
            dev_err(&device->cdev->dev, "An error occurred in the "
                "DASD device driver, reason=%s\n", errorstring);
            BUG();
            break;
        }
        retries++;
    }
    dasd_schedule_device_bh(device);
    return rc;
}

/*
 * 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)
{
    struct dasd_device *device;
    int rc;
    char errorstring[ERRORLENGTH];

    /* Check the cqr */
    rc = dasd_check_cqr(cqr);
    if (rc) {
        cqr->intrc = rc;
        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);
        dev_err(&device->cdev->dev, "An error occurred in the DASD "
            "device driver, reason=%s\n", errorstring);
        cqr->status = DASD_CQR_ERROR;
        return -EIO;
    }
    cqr->startclk = get_clock();
    cqr->starttime = jiffies;
    cqr->retries--;
    if (!test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags)) {
        cqr->lpm &= device->path_data.opm;
        if (!cqr->lpm)
            cqr->lpm = device->path_data.opm;
    }
    if (cqr->cpmode == 1) {
        rc = ccw_device_tm_start(device->cdev, cqr->cpaddr,
                     (long) cqr, cqr->lpm);
    } else {
        rc = ccw_device_start(device->cdev, cqr->cpaddr,
                      (long) cqr, cqr->lpm, 0);
    }
    switch (rc) {
    case 0:
        cqr->status = DASD_CQR_IN_IO;
        break;
    case -EBUSY:
        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                  "start_IO: device busy, retry later");
        break;
    case -ETIMEDOUT:
        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                  "start_IO: request timeout, retry later");
        break;
    case -EACCES:
        /* -EACCES indicates that the request used only a subset of the
         * available paths and all these paths are gone. If the lpm of
         * this request was only a subset of the opm (e.g. the ppm) then
         * we just do a retry with all available paths.
         * If we already use the full opm, something is amiss, and we
         * need a full path verification.
         */
        if (test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags)) {
            DBF_DEV_EVENT(DBF_WARNING, device,
                      "start_IO: selected paths gone (%x)",
                      cqr->lpm);
        } else if (cqr->lpm != device->path_data.opm) {
            cqr->lpm = device->path_data.opm;
            DBF_DEV_EVENT(DBF_DEBUG, device, "%s",
                      "start_IO: selected paths gone,"
                      " retry on all paths");
        } else {
            DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                      "start_IO: all paths in opm gone,"
                      " do path verification");
            dasd_generic_last_path_gone(device);
            device->path_data.opm = 0;
            device->path_data.ppm = 0;
            device->path_data.npm = 0;
            device->path_data.tbvpm =
                ccw_device_get_path_mask(device->cdev);
        }
        break;
    case -ENODEV:
        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                  "start_IO: -ENODEV device gone, retry");
        break;
    case -EIO:
        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                  "start_IO: -EIO device gone, retry");
        break;
    case -EINVAL:
        /* most likely caused in power management context */
        DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                  "start_IO: -EINVAL device currently "
                  "not accessible");
        break;
    default:
        /* internal error 11 - unknown rc */
        snprintf(errorstring, ERRORLENGTH, "11 %d", rc);
        dev_err(&device->cdev->dev,
            "An error occurred in the DASD device driver, "
            "reason=%s\n", errorstring);
        BUG();
        break;
    }
    cqr->intrc = rc;
    return rc;
}

/*
 * Timeout function for dasd devices. This is used for different purposes
 *  1) missing interrupt handler for normal operation
 *  2) delayed start of request where start_IO failed with -EBUSY
 *  3) timeout for missing state change interrupts
 * 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_device_timeout(unsigned long ptr)
{
    unsigned long flags;
    struct dasd_device *device;

    device = (struct dasd_device *) ptr;
    spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
    /* re-activate request queue */
    dasd_device_remove_stop_bits(device, DASD_STOPPED_PENDING);
    spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
    dasd_schedule_device_bh(device);
}

/*
 * Setup timeout for a device in jiffies.
 */
void dasd_device_set_timer(struct dasd_device *device, int expires)
{
    if (expires == 0)
        del_timer(&device->timer);
    else
        mod_timer(&device->timer, jiffies + expires);
}

/*
 * Clear timeout for a device.
 */
void dasd_device_clear_timer(struct dasd_device *device)
{
    del_timer(&device->timer);
}

static void dasd_handle_killed_request(struct ccw_device *cdev,
                       unsigned long intparm)
{
    struct dasd_ccw_req *cqr;
    struct dasd_device *device;

    if (!intparm)
        return;
    cqr = (struct dasd_ccw_req *) intparm;
    if (cqr->status != DASD_CQR_IN_IO) {
        DBF_EVENT_DEVID(DBF_DEBUG, cdev,
                "invalid status in handle_killed_request: "
                "%02x", cqr->status);
        return;
    }

    device = dasd_device_from_cdev_locked(cdev);
    if (IS_ERR(device)) {
        DBF_EVENT_DEVID(DBF_DEBUG, cdev, "%s",
                "unable to get device from cdev");
        return;
    }

    if (!cqr->startdev ||
        device != cqr->startdev ||
        strncmp(cqr->startdev->discipline->ebcname,
            (char *) &cqr->magic, 4)) {
        DBF_EVENT_DEVID(DBF_DEBUG, cdev, "%s",
                "invalid device in request");
        dasd_put_device(device);
        return;
    }

    /* Schedule request to be retried. */
    cqr->status = DASD_CQR_QUEUED;

    dasd_device_clear_timer(device);
    dasd_schedule_device_bh(device);
    dasd_put_device(device);
}

void dasd_generic_handle_state_change(struct dasd_device *device)
{
    /* First of all start sense subsystem status request. */
    dasd_eer_snss(device);

    dasd_device_remove_stop_bits(device, DASD_STOPPED_PENDING);
    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)
{
    struct dasd_ccw_req *cqr, *next;
    struct dasd_device *device;
    unsigned long long now;
    int expires;

    if (IS_ERR(irb)) {
        switch (PTR_ERR(irb)) {
        case -EIO:
            break;
        case -ETIMEDOUT:
            DBF_EVENT_DEVID(DBF_WARNING, cdev, "%s: "
                    "request timed out\n", __func__);
            break;
        default:
            DBF_EVENT_DEVID(DBF_WARNING, cdev, "%s: "
                    "unknown error %ld\n", __func__,
                    PTR_ERR(irb));
        }
        dasd_handle_killed_request(cdev, intparm);
        return;
    }

    now = get_clock();
    cqr = (struct dasd_ccw_req *) intparm;
    /* 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);
        if (IS_ERR(device))
            return;
        /* ignore unsolicited interrupts for DIAG discipline */
        if (device->discipline == dasd_diag_discipline_pointer) {
            dasd_put_device(device);
            return;
        }
        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);
    }
    if (!cqr)
        return;

    device = (struct dasd_device *) cqr->startdev;
    if (!device ||
        strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
        DBF_EVENT_DEVID(DBF_DEBUG, cdev, "%s",
                "invalid device in request");
        return;
    }

    /* Check for clear pending */
    if (cqr->status == DASD_CQR_CLEAR_PENDING &&
        scsw_fctl(&irb->scsw) & SCSW_FCTL_CLEAR_FUNC) {
        cqr->status = DASD_CQR_CLEARED;
        dasd_device_clear_timer(device);
        wake_up(&dasd_flush_wq);
        dasd_schedule_device_bh(device);
        return;
    }

    /* check status - the request might have been killed by dyn detach */
    if (cqr->status != DASD_CQR_IN_IO) {
        DBF_DEV_EVENT(DBF_DEBUG, device, "invalid status: bus_id %s, "
                  "status %02x", dev_name(&cdev->dev), cqr->status);
        return;
    }

    next = NULL;
    expires = 0;
    if (scsw_dstat(&irb->scsw) == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&
        scsw_cstat(&irb->scsw) == 0) {
        /* request was completed successfully */
        cqr->status = DASD_CQR_SUCCESS;
        cqr->stopclk = now;
        /* Start first request on queue if possible -> fast_io. */
        if (cqr->devlist.next != &device->ccw_queue) {
            next = list_entry(cqr->devlist.next,
                      struct dasd_ccw_req, devlist);
        }
    } else {  /* error */
        /*
         * If we don't want complex ERP for this request, then just
         * reset this and retry it in the fastpath
         */
        if (!test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags) &&
            cqr->retries > 0) {
            if (cqr->lpm == device->path_data.opm)
                DBF_DEV_EVENT(DBF_DEBUG, device,
                          "default ERP in fastpath "
                          "(%i retries left)",
                          cqr->retries);
            if (!test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags))
                cqr->lpm = device->path_data.opm;
            cqr->status = DASD_CQR_QUEUED;
            next = cqr;
        } else
            cqr->status = DASD_CQR_ERROR;
    }
    if (next && (next->status == DASD_CQR_QUEUED) &&
        (!device->stopped)) {
        if (device->discipline->start_IO(next) == 0)
            expires = next->expires;
    }
    if (expires != 0)
        dasd_device_set_timer(device, expires);
    else
        dasd_device_clear_timer(device);
    dasd_schedule_device_bh(device);
}

enum uc_todo dasd_generic_uc_handler(struct ccw_device *cdev, struct irb *irb)
{
    struct dasd_device *device;

    device = dasd_device_from_cdev_locked(cdev);

    if (IS_ERR(device))
        goto out;
    if (test_bit(DASD_FLAG_OFFLINE, &device->flags) ||
       device->state != device->target ||
       !device->discipline->check_for_device_change){
        dasd_put_device(device);
        goto out;
    }
    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;
}
EXPORT_SYMBOL_GPL(dasd_generic_uc_handler);

/*
 * 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 void __dasd_device_recovery(struct dasd_device *device,
                   struct dasd_ccw_req *ref_cqr)
{
    struct list_head *l, *n;
    struct dasd_ccw_req *cqr;

    /*
     * only requeue request that came from the dasd_block layer
     */
    if (!ref_cqr->block)
        return;

    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;
        }
    }
};

/*
 * Remove those ccw requests from the queue that need to be returned
 * to the upper layer.
 */
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;

    /* Process request with final status. */
    list_for_each_safe(l, n, &device->ccw_queue) {
        cqr = list_entry(l, struct dasd_ccw_req, devlist);

        /* Stop list processing at the first non-final request. */
        if (cqr->status == DASD_CQR_QUEUED ||
            cqr->status == DASD_CQR_IN_IO ||
            cqr->status == DASD_CQR_CLEAR_PENDING)
            break;
        if (cqr->status == DASD_CQR_ERROR) {
            __dasd_device_recovery(device, cqr);
        }
        /* Rechain finished requests to final queue */
        list_move_tail(&cqr->devlist, final_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_device_process_final_queue(struct dasd_device *device,
                          struct list_head *final_queue)
{
    struct list_head *l, *n;
    struct dasd_ccw_req *cqr;
    struct dasd_block *block;
    void (*callback)(struct dasd_ccw_req *, void *data);
    void *callback_data;
    char errorstring[ERRORLENGTH];

    list_for_each_safe(l, n, final_queue) {
        cqr = list_entry(l, struct dasd_ccw_req, devlist);
        list_del_init(&cqr->devlist);
        block = cqr->block;
        callback = cqr->callback;
        callback_data = cqr->callback_data;
        if (block)
            spin_lock_bh(&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:
            /* internal error 12 - wrong cqr status*/
            snprintf(errorstring, ERRORLENGTH, "12 %p %x02", cqr, cqr->status);
            dev_err(&device->cdev->dev,
                "An error occurred in the DASD device driver, "
                "reason=%s\n", errorstring);
            BUG();
        }
        if (cqr->callback != NULL)
            (callback)(cqr, callback_data);
        if (block)
            spin_unlock_bh(&block->queue_lock);
    }
}

/*
 * 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_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, 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 */
            dev_err(&device->cdev->dev,
                "cqr %p timed out (%lus) but cannot be "
                "ended, retrying in 5 s\n",
                cqr, (cqr->expires/HZ));
            cqr->expires += 5*HZ;
            dasd_device_set_timer(device, 5*HZ);
        } else {
            dev_err(&device->cdev->dev,
                "cqr %p timed out (%lus), %i retries "
                "remaining\n", cqr, (cqr->expires/HZ),
                cqr->retries);
        }
    }
}

/*
 * Take a look at the first request on the ccw queue and check
 * if it needs to be started.
 */
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, devlist);
    if (cqr->status != DASD_CQR_QUEUED)
        return;
    /* when device is stopped, return request to previous layer
     * exception: only the disconnect or unresumed bits are set and the
     * cqr is a path verification request
     */
    if (device->stopped &&
        !(!(device->stopped & ~(DASD_STOPPED_DC_WAIT | DASD_UNRESUMED_PM))
          && test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags))) {
        cqr->intrc = -EAGAIN;
        cqr->status = DASD_CQR_CLEARED;
        dasd_schedule_device_bh(device);
        return;
    }

    rc = device->discipline->start_IO(cqr);
    if (rc == 0)
        dasd_device_set_timer(device, cqr->expires);
    else if (rc == -EACCES) {
        dasd_schedule_device_bh(device);
    } else
        /* Hmpf, try again in 1/2 sec */
        dasd_device_set_timer(device, 50);
}

static void __dasd_device_check_path_events(struct dasd_device *device)
{
    int rc;

    if (device->path_data.tbvpm) {
        if (device->stopped & ~(DASD_STOPPED_DC_WAIT |
                    DASD_UNRESUMED_PM))
            return;
        rc = device->discipline->verify_path(
            device, device->path_data.tbvpm);
        if (rc)
            dasd_device_set_timer(device, 50);
        else
            device->path_data.tbvpm = 0;
    }
};

/*
 * 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.
 */
int dasd_flush_device_queue(struct dasd_device *device)
{
    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;
    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:
            rc = device->discipline->term_IO(cqr);
            if (rc) {
                /* unable to terminate requeust */
                dev_err(&device->cdev->dev,
                    "Flushing the DASD request queue "
                    "failed for request %p\n", cqr);
                /* stop flush processing */
                goto finished;
            }
            break;
        case DASD_CQR_QUEUED:
            cqr->stopclk = get_clock();
            cqr->status = DASD_CQR_CLEARED;
            break;
        default: /* no need to modify the others */
            break;
        }
        list_move_tail(&cqr->devlist, &flush_queue);
    }
finished:
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    /*
     * 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_device_tasklet(struct dasd_device *device)
{
    struct list_head final_queue;

    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_device_check_expire(device);
    /* find final requests on ccw queue */
    __dasd_device_process_ccw_queue(device, &final_queue);
    __dasd_device_check_path_events(device);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    /* Now call the callback function of requests with final status */
    __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_device_start_head(device);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    if (waitqueue_active(&shutdown_waitq))
        wake_up(&shutdown_waitq);
    dasd_put_device(device);
}

/*
 * Schedules a call to dasd_tasklet over the device tasklet.
 */
void dasd_schedule_device_bh(struct dasd_device *device)
{
    /* Protect against rescheduling. */
    if (atomic_cmpxchg (&device->tasklet_scheduled, 0, 1) != 0)
        return;
    dasd_get_device(device);
    tasklet_hi_schedule(&device->tasklet);
}

void dasd_device_set_stop_bits(struct dasd_device *device, int bits)
{
    device->stopped |= bits;
}
EXPORT_SYMBOL_GPL(dasd_device_set_stop_bits);

void dasd_device_remove_stop_bits(struct dasd_device *device, int bits)
{
    device->stopped &= ~bits;
    if (!device->stopped)
        wake_up(&generic_waitq);
}
EXPORT_SYMBOL_GPL(dasd_device_remove_stop_bits);

/*
 * Queue a request to the head of the device ccw_queue.
 * Start the I/O if possible.
 */
void dasd_add_request_head(struct dasd_ccw_req *cqr)
{
    struct dasd_device *device;
    unsigned long flags;

    device = cqr->startdev;
    spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
    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_device_bh(device);
    spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
}

/*
 * 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 *cqr)
{
    struct dasd_device *device;
    unsigned long flags;

    device = cqr->startdev;
    spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
    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_device_bh(device);
    spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
}

/*
 * Wakeup helper for the 'sleep_on' functions.
 */
void dasd_wakeup_cb(struct dasd_ccw_req *cqr, void *data)
{
    spin_lock_irq(get_ccwdev_lock(cqr->startdev->cdev));
    cqr->callback_data = DASD_SLEEPON_END_TAG;
    spin_unlock_irq(get_ccwdev_lock(cqr->startdev->cdev));
    wake_up(&generic_waitq);
}
EXPORT_SYMBOL_GPL(dasd_wakeup_cb);

static inline int _wait_for_wakeup(struct dasd_ccw_req *cqr)
{
    struct dasd_device *device;
    int rc;

    device = cqr->startdev;
    spin_lock_irq(get_ccwdev_lock(device->cdev));
    rc = (cqr->callback_data == DASD_SLEEPON_END_TAG);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    return rc;
}

/*
 * checks if error recovery is necessary, returns 1 if yes, 0 otherwise.
 */
static int __dasd_sleep_on_erp(struct dasd_ccw_req *cqr)
{
    struct dasd_device *device;
    dasd_erp_fn_t erp_fn;

    if (cqr->status == DASD_CQR_FILLED)
        return 0;
    device = cqr->startdev;
    if (test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags)) {
        if (cqr->status == DASD_CQR_TERMINATED) {
            device->discipline->handle_terminated_request(cqr);
            return 1;
        }
        if (cqr->status == DASD_CQR_NEED_ERP) {
            erp_fn = device->discipline->erp_action(cqr);
            erp_fn(cqr);
            return 1;
        }
        if (cqr->status == DASD_CQR_FAILED)
            dasd_log_sense(cqr, &cqr->irb);
        if (cqr->refers) {
            __dasd_process_erp(device, cqr);
            return 1;
        }
    }
    return 0;
}

static int __dasd_sleep_on_loop_condition(struct dasd_ccw_req *cqr)
{
    if (test_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags)) {
        if (cqr->refers) /* erp is not done yet */
            return 1;
        return ((cqr->status != DASD_CQR_DONE) &&
            (cqr->status != DASD_CQR_FAILED));
    } else
        return (cqr->status == DASD_CQR_FILLED);
}

static int _dasd_sleep_on(struct dasd_ccw_req *maincqr, int interruptible)
{
    struct dasd_device *device;
    int rc;
    struct list_head ccw_queue;
    struct dasd_ccw_req *cqr;

    INIT_LIST_HEAD(&ccw_queue);
    maincqr->status = DASD_CQR_FILLED;
    device = maincqr->startdev;
    list_add(&maincqr->blocklist, &ccw_queue);
    for (cqr = maincqr;  __dasd_sleep_on_loop_condition(cqr);
         cqr = list_first_entry(&ccw_queue,
                    struct dasd_ccw_req, blocklist)) {

        if (__dasd_sleep_on_erp(cqr))
            continue;
        if (cqr->status != DASD_CQR_FILLED) /* could be failed */
            continue;
        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;
            cqr->intrc = -EAGAIN;
            continue;
        }
        /* Don't try to start requests if device is stopped */
        if (interruptible) {
            rc = wait_event_interruptible(
                generic_waitq, !(device->stopped));
            if (rc == -ERESTARTSYS) {
                cqr->status = DASD_CQR_FAILED;
                maincqr->intrc = rc;
                continue;
            }
        } else
            wait_event(generic_waitq, !(device->stopped));

        if (!cqr->callback)
            cqr->callback = dasd_wakeup_cb;

        cqr->callback_data = DASD_SLEEPON_START_TAG;
        dasd_add_request_tail(cqr);
        if (interruptible) {
            rc = wait_event_interruptible(
                generic_waitq, _wait_for_wakeup(cqr));
            if (rc == -ERESTARTSYS) {
                dasd_cancel_req(cqr);
                /* wait (non-interruptible) for final status */
                wait_event(generic_waitq,
                       _wait_for_wakeup(cqr));
                cqr->status = DASD_CQR_FAILED;
                maincqr->intrc = rc;
                continue;
            }
        } else
            wait_event(generic_waitq, _wait_for_wakeup(cqr));
    }

    maincqr->endclk = get_clock();
    if ((maincqr->status != DASD_CQR_DONE) &&
        (maincqr->intrc != -ERESTARTSYS))
        dasd_log_sense(maincqr, &maincqr->irb);
    if (maincqr->status == DASD_CQR_DONE)
        rc = 0;
    else if (maincqr->intrc)
        rc = maincqr->intrc;
    else
        rc = -EIO;
    return rc;
}

/*
 * Queue a request to the tail of the device ccw_queue and wait for
 * it's completion.
 */
int dasd_sleep_on(struct dasd_ccw_req *cqr)
{
    return _dasd_sleep_on(cqr, 0);
}

/*
 * Queue a request to the tail of the device ccw_queue and wait
 * interruptible for it's completion.
 */
int dasd_sleep_on_interruptible(struct dasd_ccw_req *cqr)
{
    return _dasd_sleep_on(cqr, 1);
}

/*
 * Whoa nelly now it gets really hairy. For some functions (e.g. steal lock
 * for eckd devices) the currently running request has to be terminated
 * 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)
{
    struct dasd_ccw_req *cqr;
    int rc;

    if (list_empty(&device->ccw_queue))
        return 0;
    cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, devlist);
    rc = device->discipline->term_IO(cqr);
    if (!rc)
        /*
         * CQR terminated because a more important request is pending.
         * Undo decreasing of retry counter because this is
         * not an error case.
         */
        cqr->retries++;
    return rc;
}

int dasd_sleep_on_immediatly(struct dasd_ccw_req *cqr)
{
    struct dasd_device *device;
    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;
    /*
     * add new request as second
     * first the terminated cqr needs to be finished
     */
    list_add(&cqr->devlist, device->ccw_queue.next);

    /* let the bh start the request to keep them in order */
    dasd_schedule_device_bh(device);

    spin_unlock_irq(get_ccwdev_lock(device->cdev));

    wait_event(generic_waitq, _wait_for_wakeup(cqr));

    if (cqr->status == DASD_CQR_DONE)
        rc = 0;
    else if (cqr->intrc)
        rc = cqr->intrc;
    else
        rc = -EIO;
    return rc;
}

/*
 * Cancels a request that was started with dasd_sleep_on_req.
 * 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)
{
    struct dasd_device *device = cqr->startdev;
    unsigned long flags;
    int rc;

    rc = 0;
    spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
    switch (cqr->status) {
    case DASD_CQR_QUEUED:
        /* 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 */
        rc = device->discipline->term_IO(cqr);
        if (rc) {
            dev_err(&device->cdev->dev,
                "Cancelling request %p failed with rc=%d\n",
                cqr, rc);
        } else {
            cqr->stopclk = get_clock();
        }
        break;
    default: /* already finished or clear pending - do nothing */
        break;
    }
    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 */
    dasd_device_remove_stop_bits(block->base, DASD_STOPPED_PENDING);
    spin_unlock_irqrestore(get_ccwdev_lock(block->base->cdev), flags);
    dasd_schedule_block_bh(block);
}

/*
 * Setup timeout for a dasd_block in jiffies.
 */
void dasd_block_set_timer(struct dasd_block *block, int expires)
{
    if (expires == 0)
        del_timer(&block->timer);
    else
        mod_timer(&block->timer, jiffies + expires);
}

/*
 * Clear timeout for a dasd_block.
 */
void dasd_block_clear_timer(struct dasd_block *block)
{
    del_timer(&block->timer);
}

/*
 * Process finished error recovery ccw.
 */
static void __dasd_process_erp(struct dasd_device *device,
                   struct dasd_ccw_req *cqr)
{
    dasd_erp_fn_t erp_fn;

    if (cqr->status == DASD_CQR_DONE)
        DBF_DEV_EVENT(DBF_NOTICE, device, "%s", "ERP successful");
    else
        dev_err(&device->cdev->dev, "ERP failed for the DASD\n");
    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) {
        while ((req = blk_fetch_request(block->request_queue)))
            __blk_end_request_all(req, -EIO);
        return;
    }
    /* Now we try to fetch requests from the request queue */
    while ((req = blk_peek_request(queue))) {
        if (basedev->features & DASD_FEATURE_READONLY &&
            rq_data_dir(req) == WRITE) {
            DBF_DEV_EVENT(DBF_ERR, basedev,
                      "Rejecting write request %p",
                      req);
            blk_start_request(req);
            __blk_end_request_all(req, -EIO);
            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);
                dasd_device_set_stop_bits(basedev,
                              DASD_STOPPED_PENDING);
                spin_unlock_irqrestore(
                    get_ccwdev_lock(basedev->cdev), flags);
                dasd_block_set_timer(block, HZ/2);
                break;
            }
            DBF_DEV_EVENT(DBF_ERR, basedev,
                      "CCW creation failed (rc=%ld) "
                      "on request %p",
                      PTR_ERR(cqr), req);
            blk_start_request(req);
            __blk_end_request_all(req, -EIO);
            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;
        blk_start_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;
    int error = 0;

    req = (struct request *) cqr->callback_data;
    dasd_profile_end(cqr->block, cqr, req);
    status = cqr->block->base->discipline->free_cp(cqr, req);
    if (status <= 0)
        error = status ? status : -EIO;
    __blk_end_request_all(req, error);
}

/*
 * 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) {
            erp_fn = base->discipline->erp_action(cqr);
            if (IS_ERR(erp_fn(cqr)))
                continue;
            goto restart;
        }

        /* log sense for fatal error */
        if (cqr->status == DASD_CQR_FAILED) {
            dasd_log_sense(cqr, &cqr->irb);
        }

        /* 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);
            dasd_device_set_stop_bits(base, DASD_STOPPED_QUIESCE);
            spin_unlock_irqrestore(get_ccwdev_lock(base->cdev),
                           flags);
            goto restart;
        }

        /* Process finished ERP request. */
        if (cqr->refers) {
            __dasd_process_erp(base, 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;
        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) &&
            (!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);
    if (waitqueue_active(&shutdown_waitq))
        wake_up(&shutdown_waitq);
    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) {
            spin_lock_bh(&block->queue_lock);
            __dasd_process_erp(block->base, cqr);
            spin_unlock_bh(&block->queue_lock);
            /* restart list_for_xx loop since dasd_process_erp
             * might remove multiple elements */
            goto restart_cb;
        }
        /* call the callback function */
        spin_lock_irq(&block->request_queue_lock);
        cqr->endclk = get_clock();
        list_del_init(&cqr->blocklist);
        __dasd_cleanup_cqr(cqr);
        spin_unlock_irq(&block->request_queue_lock);
    }
    return rc;
}

/*
 * 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)
{
    struct dasd_block *block;

    block = queue->queuedata;
    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);
}

/*
 * Allocate and initialize request queue and default I/O scheduler.
 */
static int dasd_alloc_queue(struct dasd_block *block)
{
    int rc;

    block->request_queue = blk_init_queue(do_dasd_request,
                           &block->request_queue_lock);
    if (block->request_queue == NULL)
        return -ENOMEM;

    block->request_queue->queuedata = block;

    elevator_exit(block->request_queue->elevator);
    block->request_queue->elevator = NULL;
    rc = elevator_init(block->request_queue, "deadline");
    if (rc) {
        blk_cleanup_queue(block->request_queue);
        return rc;
    }
    return 0;
}

/*
 * Allocate and initialize request queue.
 */
static void dasd_setup_queue(struct dasd_block *block)
{
    int max;

    if (block->base->features & DASD_FEATURE_USERAW) {
        /*
         * the max_blocks value for raw_track access is 256
         * it is higher than the native ECKD value because we
         * only need one ccw per track
         * so the max_hw_sectors are
         * 2048 x 512B = 1024kB = 16 tracks
         */
        max = 2048;
    } else {
        max = block->base->discipline->max_blocks << block->s2b_shift;
    }
    blk_queue_logical_block_size(block->request_queue,
                     block->bp_block);
    blk_queue_max_hw_sectors(block->request_queue, max);
    blk_queue_max_segments(block->request_queue, -1L);
    /* with page sized segments we can translate each segement into
     * one idaw/tidaw
     */
    blk_queue_max_segment_size(block->request_queue, PAGE_SIZE);
    blk_queue_segment_boundary(block->request_queue, PAGE_SIZE - 1);
}

/*
 * Deactivate and free request queue.
 */
static void dasd_free_queue(struct dasd_block *block)
{
    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_block *block)
{
    struct request *req;

    if (!block->request_queue)
        return;

    spin_lock_irq(&block->request_queue_lock);
    while ((req = blk_fetch_request(block->request_queue)))
        __blk_end_request_all(req, -EIO);
    spin_unlock_irq(&block->request_queue_lock);
}

static int dasd_open(struct block_device *bdev, fmode_t mode)
{
    struct dasd_device *base;
    int rc;

    base = dasd_device_from_gendisk(bdev->bd_disk);
    if (!base)
        return -ENODEV;

    atomic_inc(&base->block->open_count);
    if (test_bit(DASD_FLAG_OFFLINE, &base->flags)) {
        rc = -ENODEV;
        goto unlock;
    }

    if (!try_module_get(base->discipline->owner)) {
        rc = -EINVAL;
        goto unlock;
    }

    if (dasd_probeonly) {
        dev_info(&base->cdev->dev,
             "Accessing the DASD failed because it is in "
             "probeonly mode\n");
        rc = -EPERM;
        goto out;
    }

    if (base->state <= DASD_STATE_BASIC) {
        DBF_DEV_EVENT(DBF_ERR, base, " %s",
                  " Cannot open unrecognized device");
        rc = -ENODEV;
        goto out;
    }

    if ((mode & FMODE_WRITE) &&
        (test_bit(DASD_FLAG_DEVICE_RO, &base->flags) ||
         (base->features & DASD_FEATURE_READONLY))) {
        rc = -EROFS;
        goto out;
    }

    dasd_put_device(base);
    return 0;

out:
    module_put(base->discipline->owner);
unlock:
    atomic_dec(&base->block->open_count);
    dasd_put_device(base);
    return rc;
}

static int dasd_release(struct gendisk *disk, fmode_t mode)
{
    struct dasd_device *base;

    base = dasd_device_from_gendisk(disk);
    if (!base)
        return -ENODEV;

    atomic_dec(&base->block->open_count);
    module_put(base->discipline->owner);
    dasd_put_device(base);
    return 0;
}

/*
 * Return disk geometry.
 */
static int dasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
    struct dasd_device *base;

    base = dasd_device_from_gendisk(bdev->bd_disk);
    if (!base)
        return -ENODEV;

    if (!base->discipline ||
        !base->discipline->fill_geometry) {
        dasd_put_device(base);
        return -EINVAL;
    }
    base->discipline->fill_geometry(base->block, geo);
    geo->start = get_start_sect(bdev) >> base->block->s2b_shift;
    dasd_put_device(base);
    return 0;
}

const struct block_device_operations
dasd_device_operations = {
    .owner      = THIS_MODULE,
    .open       = dasd_open,
    .release    = dasd_release,
    .ioctl      = dasd_ioctl,
    .compat_ioctl   = dasd_ioctl,
    .getgeo     = dasd_getgeo,
};

/*******************************************************************************
 * end of block device operations
 */

static void
dasd_exit(void)
{
#ifdef CONFIG_PROC_FS
    dasd_proc_exit();
#endif
    dasd_eer_exit();
        if (dasd_page_cache != NULL) {
        kmem_cache_destroy(dasd_page_cache);
        dasd_page_cache = NULL;
    }
    dasd_gendisk_exit();
    dasd_devmap_exit();
    if (dasd_debug_area != NULL) {
        debug_unregister(dasd_debug_area);
        dasd_debug_area = NULL;
    }
    dasd_statistics_removeroot();
}

/*
 * SECTION: common functions for ccw_driver use
 */

/*
 * Is the device read-only?
 * Note that this function does not report the setting of the
 * readonly device attribute, but how it is configured in z/VM.
 */
int dasd_device_is_ro(struct dasd_device *device)
{
    struct ccw_dev_id dev_id;
    struct diag210 diag_data;
    int rc;

    if (!MACHINE_IS_VM)
        return 0;
    ccw_device_get_id(device->cdev, &dev_id);
    memset(&diag_data, 0, sizeof(diag_data));
    diag_data.vrdcdvno = dev_id.devno;
    diag_data.vrdclen = sizeof(diag_data);
    rc = diag210(&diag_data);
    if (rc == 0 || rc == 2) {
        return diag_data.vrdcvfla & 0x80;
    } else {
        DBF_EVENT(DBF_WARNING, "diag210 failed for dev=%04x with rc=%d",
              dev_id.devno, rc);
        return 0;
    }
}
EXPORT_SYMBOL_GPL(dasd_device_is_ro);

static void dasd_generic_auto_online(void *data, async_cookie_t cookie)
{
    struct ccw_device *cdev = data;
    int ret;

    ret = ccw_device_set_online(cdev);
    if (ret)
        pr_warning("%s: Setting the DASD online failed with rc=%d\n",
               dev_name(&cdev->dev), ret);
}

/*
 * 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 ret;

    ret = dasd_add_sysfs_files(cdev);
    if (ret) {
        DBF_EVENT_DEVID(DBF_WARNING, cdev, "%s",
                "dasd_generic_probe: could not add "
                "sysfs entries");
        return ret;
    }
    cdev->handler = &dasd_int_handler;

    /*
     * Automatically online either all dasd devices (dasd_autodetect)
     * or all devices specified with dasd= parameters during
     * initial probe.
     */
    if ((dasd_get_feature(cdev, DASD_FEATURE_INITIAL_ONLINE) > 0 ) ||
        (dasd_autodetect && dasd_busid_known(dev_name(&cdev->dev)) != 0))
        async_schedule(dasd_generic_auto_online, cdev);
    return 0;
}

/*
 * 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)
{
    struct dasd_device *device;
    struct dasd_block *block;

    cdev->handler = NULL;

    dasd_remove_sysfs_files(cdev);
    device = dasd_device_from_cdev(cdev);
    if (IS_ERR(device))
        return;
    if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {
        /* Already doing offline processing */
        dasd_put_device(device);
        return;
    }
    /*
     * This device is removed unconditionally. Set offline
     * flag to prevent dasd_open from opening it while it is
     * no quite down yet.
     */
    dasd_set_target_state(device, DASD_STATE_NEW);
    /* dasd_delete_device destroys the device reference. */
    block = device->block;
    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);
}

/*
 * Activate a device. This is called from dasd_{eckd,fba}_probe() when either
 * 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)
{
    struct dasd_discipline *discipline;
    struct dasd_device *device;
    int rc;

    /* first online clears initial online feature flag */
    dasd_set_feature(cdev, DASD_FEATURE_INITIAL_ONLINE, 0);
    device = dasd_create_device(cdev);
    if (IS_ERR(device))
        return PTR_ERR(device);

    discipline = base_discipline;
    if (device->features & DASD_FEATURE_USEDIAG) {
        if (!dasd_diag_discipline_pointer) {
            pr_warning("%s Setting the DASD online failed because "
                   "of missing DIAG discipline\n",
                   dev_name(&cdev->dev));
            dasd_delete_device(device);
            return -ENODEV;
        }
        discipline = dasd_diag_discipline_pointer;
    }
    if (!try_module_get(base_discipline->owner)) {
        dasd_delete_device(device);
        return -EINVAL;
    }
    if (!try_module_get(discipline->owner)) {
        module_put(base_discipline->owner);
        dasd_delete_device(device);
        return -EINVAL;
    }
    device->base_discipline = base_discipline;
    device->discipline = discipline;

    /* check_device will allocate block device if necessary */
    rc = discipline->check_device(device);
    if (rc) {
        pr_warning("%s Setting the DASD online with discipline %s "
               "failed with rc=%i\n",
               dev_name(&cdev->dev), discipline->name, rc);
        module_put(discipline->owner);
        module_put(base_discipline->owner);
        dasd_delete_device(device);
        return rc;
    }

    dasd_set_target_state(device, DASD_STATE_ONLINE);
    if (device->state <= DASD_STATE_KNOWN) {
        pr_warning("%s Setting the DASD online failed because of a "
               "missing discipline\n", dev_name(&cdev->dev));
        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",
                dev_name(&cdev->dev));

    wait_event(dasd_init_waitq, _wait_for_device(device));

    dasd_put_device(device);
    return rc;
}

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);
    if (IS_ERR(device))
        return PTR_ERR(device);
    if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {
        /* Already doing offline processing */
        dasd_put_device(device);
        return 0;
    }
    /*
     * We must make sure that this device is currently not in use.
     * The open_count is increased for every opener, that includes
     * the blkdev_get in dasd_scan_partitions. We are only interested
     * in the other openers.
     */
    if (device->block) {
        max_count = device->block->bdev ? 0 : -1;
        open_count = atomic_read(&device->block->open_count);
        if (open_count > max_count) {
            if (open_count > 0)
                pr_warning("%s: The DASD cannot be set offline "
                       "with open count %i\n",
                       dev_name(&cdev->dev), open_count);
            else
                pr_warning("%s: The DASD cannot be set offline "
                       "while it is in use\n",
                       dev_name(&cdev->dev));
            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;
    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_last_path_gone(struct dasd_device *device)
{
    struct dasd_ccw_req *cqr;

    dev_warn(&device->cdev->dev, "No operational channel path is left "
         "for the device\n");
    DBF_DEV_EVENT(DBF_WARNING, device, "%s", "last path gone");
    /* First of all call extended error reporting. */
    dasd_eer_write(device, NULL, DASD_EER_NOPATH);

    if (device->state < DASD_STATE_BASIC)
        return 0;
    /* Device is active. We want to keep it. */
    list_for_each_entry(cqr, &device->ccw_queue, devlist)
        if ((cqr->status == DASD_CQR_IN_IO) ||
            (cqr->status == DASD_CQR_CLEAR_PENDING)) {
            cqr->status = DASD_CQR_QUEUED;
            cqr->retries++;
        }
    dasd_device_set_stop_bits(device, DASD_STOPPED_DC_WAIT);
    dasd_device_clear_timer(device);
    dasd_schedule_device_bh(device);
    return 1;
}
EXPORT_SYMBOL_GPL(dasd_generic_last_path_gone);

int dasd_generic_path_operational(struct dasd_device *device)
{
    dev_info(&device->cdev->dev, "A channel path to the device has become "
         "operational\n");
    DBF_DEV_EVENT(DBF_WARNING, device, "%s", "path operational");
    dasd_device_remove_stop_bits(device, DASD_STOPPED_DC_WAIT);
    if (device->stopped & DASD_UNRESUMED_PM) {
        dasd_device_remove_stop_bits(device, DASD_UNRESUMED_PM);
        dasd_restore_device(device);
        return 1;
    }
    dasd_schedule_device_bh(device);
    if (device->block)
        dasd_schedule_block_bh(device->block);
    return 1;
}
EXPORT_SYMBOL_GPL(dasd_generic_path_operational);

int dasd_generic_notify(struct ccw_device *cdev, int event)
{
    struct dasd_device *device;
    int ret;

    device = dasd_device_from_cdev_locked(cdev);
    if (IS_ERR(device))
        return 0;
    ret = 0;
    switch (event) {
    case CIO_GONE:
    case CIO_BOXED:
    case CIO_NO_PATH:
        device->path_data.opm = 0;
        device->path_data.ppm = 0;
        device->path_data.npm = 0;
        ret = dasd_generic_last_path_gone(device);
        break;
    case CIO_OPER:
        ret = 1;
        if (device->path_data.opm)
            ret = dasd_generic_path_operational(device);
        break;
    }
    dasd_put_device(device);
    return ret;
}

void dasd_generic_path_event(struct ccw_device *cdev, int *path_event)
{
    int chp;
    __u8 oldopm, eventlpm;
    struct dasd_device *device;

    device = dasd_device_from_cdev_locked(cdev);
    if (IS_ERR(device))
        return;
    for (chp = 0; chp < 8; chp++) {
        eventlpm = 0x80 >> chp;
        if (path_event[chp] & PE_PATH_GONE) {
            oldopm = device->path_data.opm;
            device->path_data.opm &= ~eventlpm;
            device->path_data.ppm &= ~eventlpm;
            device->path_data.npm &= ~eventlpm;
            if (oldopm && !device->path_data.opm)
                dasd_generic_last_path_gone(device);
        }
        if (path_event[chp] & PE_PATH_AVAILABLE) {
            device->path_data.opm &= ~eventlpm;
            device->path_data.ppm &= ~eventlpm;
            device->path_data.npm &= ~eventlpm;
            device->path_data.tbvpm |= eventlpm;
            dasd_schedule_device_bh(device);
        }
        if (path_event[chp] & PE_PATHGROUP_ESTABLISHED) {
            if (!(device->path_data.opm & eventlpm) &&
                !(device->path_data.tbvpm & eventlpm)) {
                /*
                 * we can not establish a pathgroup on an
                 * unavailable path, so trigger a path
                 * verification first
                 */
                device->path_data.tbvpm |= eventlpm;
                dasd_schedule_device_bh(device);
            }
            DBF_DEV_EVENT(DBF_WARNING, device, "%s",
                      "Pathgroup re-established\n");
            if (device->discipline->kick_validate)
                device->discipline->kick_validate(device);
        }
    }
    dasd_put_device(device);
}
EXPORT_SYMBOL_GPL(dasd_generic_path_event);

int dasd_generic_verify_path(struct dasd_device *device, __u8 lpm)
{
    if (!device->path_data.opm && lpm) {
        device->path_data.opm = lpm;
        dasd_generic_path_operational(device);
    } else
        device->path_data.opm |= lpm;
    return 0;
}
EXPORT_SYMBOL_GPL(dasd_generic_verify_path);


int dasd_generic_pm_freeze(struct ccw_device *cdev)
{
    struct dasd_ccw_req *cqr, *n;
    int rc;
    struct list_head freeze_queue;
    struct dasd_device *device = dasd_device_from_cdev(cdev);

    if (IS_ERR(device))
        return PTR_ERR(device);

    /* mark device as suspended */
    set_bit(DASD_FLAG_SUSPENDED, &device->flags);

    if (device->discipline->freeze)
        rc = device->discipline->freeze(device);

    /* disallow new I/O  */
    dasd_device_set_stop_bits(device, DASD_STOPPED_PM);
    /* clear active requests */
    INIT_LIST_HEAD(&freeze_queue);
    spin_lock_irq(get_ccwdev_lock(cdev));
    rc = 0;
    list_for_each_entry_safe(cqr, n, &device->ccw_queue, devlist) {
        /* Check status and move request to flush_queue */
        if (cqr->status == DASD_CQR_IN_IO) {
            rc = device->discipline->term_IO(cqr);
            if (rc) {
                /* unable to terminate requeust */
                dev_err(&device->cdev->dev,
                    "Unable to terminate request %p "
                    "on suspend\n", cqr);
                spin_unlock_irq(get_ccwdev_lock(cdev));
                dasd_put_device(device);
                return rc;
            }
        }
        list_move_tail(&cqr->devlist, &freeze_queue);
    }

    spin_unlock_irq(get_ccwdev_lock(cdev));

    list_for_each_entry_safe(cqr, n, &freeze_queue, devlist) {
        wait_event(dasd_flush_wq,
               (cqr->status != DASD_CQR_CLEAR_PENDING));
        if (cqr->status == DASD_CQR_CLEARED)
            cqr->status = DASD_CQR_QUEUED;
    }
    /* move freeze_queue to start of the ccw_queue */
    spin_lock_irq(get_ccwdev_lock(cdev));
    list_splice_tail(&freeze_queue, &device->ccw_queue);
    spin_unlock_irq(get_ccwdev_lock(cdev));

    dasd_put_device(device);
    return rc;
}
EXPORT_SYMBOL_GPL(dasd_generic_pm_freeze);

int dasd_generic_restore_device(struct ccw_device *cdev)
{
    struct dasd_device *device = dasd_device_from_cdev(cdev);
    int rc = 0;

    if (IS_ERR(device))
        return PTR_ERR(device);

    /* allow new IO again */
    dasd_device_remove_stop_bits(device,
                     (DASD_STOPPED_PM | DASD_UNRESUMED_PM));

    dasd_schedule_device_bh(device);

    /*
     * call discipline restore function
     * if device is stopped do nothing e.g. for disconnected devices
     */
    if (device->discipline->restore && !(device->stopped))
        rc = device->discipline->restore(device);
    if (rc || device->stopped)
        /*
         * if the resume failed for the DASD we put it in
         * an UNRESUMED stop state
         */
        device->stopped |= DASD_UNRESUMED_PM;

    if (device->block)
        dasd_schedule_block_bh(device->block);

    clear_bit(DASD_FLAG_SUSPENDED, &device->flags);
    dasd_put_device(device);
    return 0;
}
EXPORT_SYMBOL_GPL(dasd_generic_restore_device);

static struct dasd_ccw_req *dasd_generic_build_rdc(struct dasd_device *device,
                           void *rdc_buffer,
                           int rdc_buffer_size,
                           int magic)
{
    struct dasd_ccw_req *cqr;
    struct ccw1 *ccw;
    unsigned long *idaw;

    cqr = dasd_smalloc_request(magic, 1 /* RDC */, rdc_buffer_size, device);

    if (IS_ERR(cqr)) {
        /* internal error 13 - Allocating the RDC request failed*/
        dev_err(&device->cdev->dev,
             "An error occurred in the DASD device driver, "
             "reason=%s\n", "13");
        return cqr;
    }

    ccw = cqr->cpaddr;
    ccw->cmd_code = CCW_CMD_RDC;
    if (idal_is_needed(rdc_buffer, rdc_buffer_size)) {
        idaw = (unsigned long *) (cqr->data);
        ccw->cda = (__u32)(addr_t) idaw;
        ccw->flags = CCW_FLAG_IDA;
        idaw = idal_create_words(idaw, rdc_buffer, rdc_buffer_size);
    } else {
        ccw->cda = (__u32)(addr_t) rdc_buffer;
        ccw->flags = 0;
    }

    ccw->count = rdc_buffer_size;
    cqr->startdev = device;
    cqr->memdev = device;
    cqr->expires = 10*HZ;
    cqr->retries = 256;
    cqr->buildclk = get_clock();
    cqr->status = DASD_CQR_FILLED;
    return cqr;
}


int dasd_generic_read_dev_chars(struct dasd_device *device, int magic,
                void *rdc_buffer, int rdc_buffer_size)
{
    int ret;
    struct dasd_ccw_req *cqr;

    cqr = dasd_generic_build_rdc(device, rdc_buffer, rdc_buffer_size,
                     magic);
    if (IS_ERR(cqr))
        return PTR_ERR(cqr);

    ret = dasd_sleep_on(cqr);
    dasd_sfree_request(cqr, cqr->memdev);
    return ret;
}
EXPORT_SYMBOL_GPL(dasd_generic_read_dev_chars);

/*
 *   In command mode and transport mode we need to look for sense
 *   data in different places. The sense data itself is allways
 *   an array of 32 bytes, so we can unify the sense data access
 *   for both modes.
 */
char *dasd_get_sense(struct irb *irb)
{
    struct tsb *tsb = NULL;
    char *sense = NULL;

    if (scsw_is_tm(&irb->scsw) && (irb->scsw.tm.fcxs == 0x01)) {
        if (irb->scsw.tm.tcw)
            tsb = tcw_get_tsb((struct tcw *)(unsigned long)
                      irb->scsw.tm.tcw);
        if (tsb && tsb->length == 64 && tsb->flags)
            switch (tsb->flags & 0x07) {
            case 1: /* tsa_iostat */
                sense = tsb->tsa.iostat.sense;
                break;
            case 2: /* tsa_ddpc */
                sense = tsb->tsa.ddpc.sense;
                break;
            default:
                /* currently we don't use interrogate data */
                break;
            }
    } else if (irb->esw.esw0.erw.cons) {
        sense = irb->ecw;
    }
    return sense;
}
EXPORT_SYMBOL_GPL(dasd_get_sense);

static inline int _wait_for_empty_queues(struct dasd_device *device)
{
    if (device->block)
        return list_empty(&device->ccw_queue) &&
            list_empty(&device->block->ccw_queue);
    else
        return list_empty(&device->ccw_queue);
}

void dasd_generic_shutdown(struct ccw_device *cdev)
{
    struct dasd_device *device;

    device = dasd_device_from_cdev(cdev);
    if (IS_ERR(device))
        return;

    if (device->block)
        dasd_schedule_block_bh(device->block);

    dasd_schedule_device_bh(device);

    wait_event(shutdown_waitq, _wait_for_empty_queues(device));
}
EXPORT_SYMBOL_GPL(dasd_generic_shutdown);

static int __init dasd_init(void)
{
    int rc;

    init_waitqueue_head(&dasd_init_waitq);
    init_waitqueue_head(&dasd_flush_wq);
    init_waitqueue_head(&generic_waitq);
    init_waitqueue_head(&shutdown_waitq);

    /* register 'common' DASD debug area, used for all DBF_XXX calls */
    dasd_debug_area = debug_register("dasd", 1, 1, 8 * sizeof(long));
    if (dasd_debug_area == NULL) {
        rc = -ENOMEM;
        goto failed;
    }
    debug_register_view(dasd_debug_area, &debug_sprintf_view);
    debug_set_level(dasd_debug_area, DBF_WARNING);

    DBF_EVENT(DBF_EMERG, "%s", "debug area created");

    dasd_diag_discipline_pointer = NULL;

    dasd_statistics_createroot();

    rc = dasd_devmap_init();
    if (rc)
        goto failed;
    rc = dasd_gendisk_init();
    if (rc)
        goto failed;
    rc = dasd_parse();
    if (rc)
        goto failed;
    rc = dasd_eer_init();
    if (rc)
        goto failed;
#ifdef CONFIG_PROC_FS
    rc = dasd_proc_init();
    if (rc)
        goto failed;
#endif

    return 0;
failed:
    pr_info("The DASD device driver could not be initialized\n");
    dasd_exit();
    return rc;
}

module_init(dasd_init);
module_exit(dasd_exit);

EXPORT_SYMBOL(dasd_debug_area);
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_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_device_bh);
EXPORT_SYMBOL(dasd_schedule_block_bh);
EXPORT_SYMBOL(dasd_set_target_state);
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);
EXPORT_SYMBOL(dasd_sleep_on_interruptible);
EXPORT_SYMBOL(dasd_smalloc_request);
EXPORT_SYMBOL(dasd_start_IO);
EXPORT_SYMBOL(dasd_term_IO);

EXPORT_SYMBOL_GPL(dasd_generic_probe);
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);