// SPDX-License-Identifier: GPL-2.0
/*
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 *                  Horst Hummel <Horst.Hummel@de.ibm.com>
 *                  Carsten Otte <Cotte@de.ibm.com>
 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * 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_DIAG_MOD           "dasd_diag_mod"

static unsigned int queue_depth = 32;
static unsigned int nr_hw_queues = 4;

module_param(queue_depth, uint, 0444);
MODULE_PARM_DESC(queue_depth, "Default queue depth for new DASD devices");

module_param(nr_hw_queues, uint, 0444);
MODULE_PARM_DESC(nr_hw_queues, "Default number of hardware queues for new DASD devices");

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

MODULE_AUTHOR("Holger Smolinski <Holger.Smolinski@de.ibm.com>");
MODULE_DESCRIPTION("Linux on S/390 DASD device driver,"
                   " Copyright IBM Corp. 2000");
MODULE_LICENSE("GPL");

/*
 * SECTION: prototypes for static functions of dasd.c
 */
static int  dasd_alloc_queue(struct dasd_block *);
static void dasd_free_queue(struct dasd_block *);
static int dasd_flush_block_queue(struct dasd_block *);
static void dasd_device_tasklet(unsigned long);
static void dasd_block_tasklet(unsigned long);
static void do_kick_device(struct work_struct *);
static void do_reload_device(struct work_struct *);
static void do_requeue_requests(struct work_struct *);
static void dasd_return_cqr_cb(struct dasd_ccw_req *, void *);
static void dasd_device_timeout(struct timer_list *);
static void dasd_block_timeout(struct timer_list *);
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 *);
static void dasd_hosts_init(struct dentry *, struct dasd_device *);
static void dasd_hosts_exit(struct dasd_device *);

/*
 * 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);
        }
        /* Get two pages for ese format. */
        device->ese_mem = (void *)__get_free_pages(GFP_ATOMIC | GFP_DMA, 1);
        if (!device->ese_mem) {
                free_page((unsigned long) 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);
        dasd_init_chunklist(&device->ese_chunks, device->ese_mem, PAGE_SIZE * 2);
        spin_lock_init(&device->mem_lock);
        atomic_set(&device->tasklet_scheduled, 0);
        tasklet_init(&device->tasklet, dasd_device_tasklet,
                     (unsigned long) device);
        INIT_LIST_HEAD(&device->ccw_queue);
        timer_setup(&device->timer, dasd_device_timeout, 0);
        INIT_WORK(&device->kick_work, do_kick_device);
        INIT_WORK(&device->reload_device, do_reload_device);
        INIT_WORK(&device->requeue_requests, do_requeue_requests);
        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_pages((unsigned long) device->ese_mem, 1);
        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);

        atomic_set(&block->tasklet_scheduled, 0);
        tasklet_init(&block->tasklet, dasd_block_tasklet,
                     (unsigned long) block);
        INIT_LIST_HEAD(&block->ccw_queue);
        spin_lock_init(&block->queue_lock);
        INIT_LIST_HEAD(&block->format_list);
        spin_lock_init(&block->format_lock);
        timer_setup(&block->timer, dasd_block_timeout, 0);
        spin_lock_init(&block->profile.lock);

        return block;
}
EXPORT_SYMBOL_GPL(dasd_alloc_block);

/*
 * Free memory of a device structure.
 */
void dasd_free_block(struct dasd_block *block)
{
        kfree(block);
}
EXPORT_SYMBOL_GPL(dasd_free_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);
        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 = 0;

        /* 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);
        dasd_hosts_init(device->debugfs_dentry, device);

        /* 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 rc;
}

/*
 * 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->discipline->basic_to_known) {
                rc = device->discipline->basic_to_known(device);
                if (rc)
                        return rc;
        }

        if (device->block) {
                dasd_profile_exit(&device->block->profile);
                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);
        dasd_hosts_exit(device);
        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;
        struct gendisk *disk;

        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;
                                disk = device->block->gdp;
                                kobject_uevent(&disk_to_dev(disk)->kobj,
                                               KOBJ_CHANGE);
                                goto out;
                        }
                        return rc;
                }
                if (device->discipline->setup_blk_queue)
                        device->discipline->setup_blk_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;
                        return rc;
                }
        } else {
                device->state = DASD_STATE_READY;
        }
out:
        if (device->discipline->basic_to_ready)
                rc = device->discipline->basic_to_ready(device);
        return rc;
}

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);
}

/*
 * 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_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)
{
        device->state = DASD_STATE_ONLINE;
        if (device->block) {
                dasd_schedule_block_bh(device->block);
                if ((device->features & DASD_FEATURE_USERAW)) {
                        kobject_uevent(&disk_to_dev(device->block->gdp)->kobj,
                                        KOBJ_CHANGE);
                        return 0;
                }
                disk_uevent(device->block->bdev->bd_disk, KOBJ_CHANGE);
        }
        return 0;
}

/*
 * Stop the requeueing of requests again.
 */
static int dasd_state_online_to_ready(struct dasd_device *device)
{
        int rc;

        if (device->discipline->online_to_ready) {
                rc = device->discipline->online_to_ready(device);
                if (rc)
                        return rc;
        }

        device->state = DASD_STATE_READY;
        if (device->block && !(device->features & DASD_FEATURE_USERAW))
                disk_uevent(device->block->bdev->bd_disk, KOBJ_CHANGE);
        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. */
        if (!schedule_work(&device->kick_work))
                dasd_put_device(device);
}
EXPORT_SYMBOL(dasd_kick_device);

/*
 * 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. */
        if (!schedule_work(&device->reload_device))
                dasd_put_device(device);
}
EXPORT_SYMBOL(dasd_reload_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);
}
EXPORT_SYMBOL(dasd_enable_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 dasd_global_profile = {
        .lock = __SPIN_LOCK_UNLOCKED(dasd_global_profile.lock),
};
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;

        spin_lock(&dasd_global_profile.lock);
        if (dasd_global_profile.data) {
                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_unlock(&dasd_global_profile.lock);

        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));
                        ktime_get_real_ts64(&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)
{
        unsigned long strtime, irqtime, endtime, tottime;
        unsigned long tottimeps, sectors;
        struct dasd_device *device;
        int sectors_ind, tottime_ind, tottimeps_ind, strtime_ind;
        int irqtime_ind, irqtimeps_ind, endtime_ind;
        struct dasd_profile_info *data;

        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);

        spin_lock(&dasd_global_profile.lock);
        if (dasd_global_profile.data) {
                data = dasd_global_profile.data;
                data->dasd_sum_times += tottime;
                data->dasd_sum_time_str += strtime;
                data->dasd_sum_time_irq += irqtime;
                data->dasd_sum_time_end += endtime;
                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_unlock(&dasd_global_profile.lock);

        spin_lock(&block->profile.lock);
        if (block->profile.data) {
                data = block->profile.data;
                data->dasd_sum_times += tottime;
                data->dasd_sum_time_str += strtime;
                data->dasd_sum_time_irq += irqtime;
                data->dasd_sum_time_end += endtime;
                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) {
                data = device->profile.data;
                data->dasd_sum_times += tottime;
                data->dasd_sum_time_str += strtime;
                data->dasd_sum_time_irq += irqtime;
                data->dasd_sum_time_end += endtime;
                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));
        ktime_get_real_ts64(&data->starttod);
        spin_unlock_bh(&profile->lock);
}

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;
        }
        ktime_get_real_ts64(&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)
                        goto out;
                rc = user_len;
                if (prof == &dasd_global_profile) {
                        dasd_profile_reset(prof);
                        dasd_global_profile_level = DASD_PROFILE_GLOBAL_ONLY;
                }
        } else if (strncmp(str, "off", 3) == 0) {
                if (prof == &dasd_global_profile)
                        dasd_global_profile_level = DASD_PROFILE_OFF;
                dasd_profile_off(prof);
        } else
                rc = -EINVAL;
out:
        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 %lld.%09ld\n",
                   (s64)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, "avg_total %lu\n", data->dasd_io_reqs ?
                   data->dasd_sum_times / data->dasd_io_reqs : 0UL);
        seq_printf(m, "avg_build_to_ssch %lu\n", data->dasd_io_reqs ?
                   data->dasd_sum_time_str / data->dasd_io_reqs : 0UL);
        seq_printf(m, "avg_ssch_to_irq %lu\n", data->dasd_io_reqs ?
                   data->dasd_sum_time_irq / data->dasd_io_reqs : 0UL);
        seq_printf(m, "avg_irq_to_end %lu\n", data->dasd_io_reqs ?
                   data->dasd_sum_time_end / data->dasd_io_reqs : 0UL);
        seq_puts(m, "histogram_sectors ");
        dasd_stats_array(m, data->dasd_io_secs);
        seq_puts(m, "histogram_io_times ");
        dasd_stats_array(m, data->dasd_io_times);
        seq_puts(m, "histogram_io_times_weighted ");
        dasd_stats_array(m, data->dasd_io_timps);
        seq_puts(m, "histogram_time_build_to_ssch ");
        dasd_stats_array(m, data->dasd_io_time1);
        seq_puts(m, "histogram_time_ssch_to_irq ");
        dasd_stats_array(m, data->dasd_io_time2);

        seq_puts(m, "histogram_time_ssch_to_irq_weighted ");
        dasd_stats_array(m, data->dasd_io_time2ps);
        seq_puts(m, "histogram_time_irq_to_end ");
        dasd_stats_array(m, data->dasd_io_time3);
        seq_puts(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_puts(m, "histogram_read_sectors ");
        dasd_stats_array(m, data->dasd_read_secs);
        seq_puts(m, "histogram_read_times ");
        dasd_stats_array(m, data->dasd_read_times);
        seq_puts(m, "histogram_read_time_build_to_ssch ");
        dasd_stats_array(m, data->dasd_read_time1);
        seq_puts(m, "histogram_read_time_ssch_to_irq ");
        dasd_stats_array(m, data->dasd_read_time2);
        seq_puts(m, "histogram_read_time_irq_to_end ");
        dasd_stats_array(m, data->dasd_read_time3);
        seq_puts(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_puts(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 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);
        debugfs_remove(profile->dentry);
        profile->dentry = NULL;
}

static void dasd_statistics_removeroot(void)
{
        dasd_global_profile_level = DASD_PROFILE_OFF;
        dasd_profile_exit(&dasd_global_profile);
        debugfs_remove(dasd_debugfs_global_entry);
        debugfs_remove(dasd_debugfs_root_entry);
}

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

        dasd_debugfs_root_entry = 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;
        dasd_profile_init(&dasd_global_profile, dasd_debugfs_global_entry);
        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_puts(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 */

static int dasd_hosts_show(struct seq_file *m, void *v)
{
        struct dasd_device *device;
        int rc = -EOPNOTSUPP;

        device = m->private;
        dasd_get_device(device);

        if (device->discipline->hosts_print)
                rc = device->discipline->hosts_print(device, m);

        dasd_put_device(device);
        return rc;
}

DEFINE_SHOW_ATTRIBUTE(dasd_hosts);

static void dasd_hosts_exit(struct dasd_device *device)
{
        debugfs_remove(device->hosts_dentry);
        device->hosts_dentry = NULL;
}

static void dasd_hosts_init(struct dentry *base_dentry,
                            struct dasd_device *device)
{
        struct dentry *pde;
        umode_t mode;

        if (!base_dentry)
                return;

        mode = S_IRUSR | S_IFREG;
        pde = debugfs_create_file("host_access_list", mode, base_dentry,
                                  device, &dasd_hosts_fops);
        if (pde && !IS_ERR(pde))
                device->hosts_dentry = pde;
}

struct dasd_ccw_req *dasd_smalloc_request(int magic, int cplength, int datasize,
                                          struct dasd_device *device,
                                          struct dasd_ccw_req *cqr)
{
        unsigned long flags;
        char *data, *chunk;
        int size = 0;

        if (cplength > 0)
                size += cplength * sizeof(struct ccw1);
        if (datasize > 0)
                size += datasize;
        if (!cqr)
                size += (sizeof(*cqr) + 7L) & -8L;

        spin_lock_irqsave(&device->mem_lock, flags);
        data = chunk = dasd_alloc_chunk(&device->ccw_chunks, size);
        spin_unlock_irqrestore(&device->mem_lock, flags);
        if (!chunk)
                return ERR_PTR(-ENOMEM);
        if (!cqr) {
                cqr = (void *) data;
                data += (sizeof(*cqr) + 7L) & -8L;
        }
        memset(cqr, 0, sizeof(*cqr));
        cqr->mem_chunk = chunk;
        if (cplength > 0) {
                cqr->cpaddr = data;
                data += cplength * sizeof(struct ccw1);
                memset(cqr->cpaddr, 0, cplength * sizeof(struct ccw1));
        }
        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;
}
EXPORT_SYMBOL(dasd_smalloc_request);

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

        cqr_size = (sizeof(*cqr) + 7L) & -8L;
        size = cqr_size;
        if (cplength > 0)
                size += cplength * sizeof(struct ccw1);
        if (datasize > 0)
                size += datasize;

        spin_lock_irqsave(&device->mem_lock, flags);
        cqr = dasd_alloc_chunk(&device->ese_chunks, size);
        spin_unlock_irqrestore(&device->mem_lock, flags);
        if (!cqr)
                return ERR_PTR(-ENOMEM);
        memset(cqr, 0, sizeof(*cqr));
        data = (char *)cqr + cqr_size;
        cqr->cpaddr = NULL;
        if (cplength > 0) {
                cqr->cpaddr = 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;
}
EXPORT_SYMBOL(dasd_fmalloc_request);

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->mem_chunk);
        spin_unlock_irqrestore(&device->mem_lock, flags);
        dasd_put_device(device);
}
EXPORT_SYMBOL(dasd_sfree_request);

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

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

/*
 * 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_tod_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 -EINVAL:
                        /*
                         * device not valid so no I/O could be running
                         * handle CQR as termination successful
                         */
                        cqr->status = DASD_CQR_CLEARED;
                        cqr->stopclk = get_tod_clock();
                        cqr->starttime = 0;
                        /* no retries for invalid devices */
                        cqr->retries = -1;
                        DBF_DEV_EVENT(DBF_ERR, device, "%s",
                                      "EINVAL, handle as terminated");
                        /* fake rc to success */
                        rc = 0;
                        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;
}
EXPORT_SYMBOL(dasd_term_IO);

/*
 * 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_tod_clock();
        cqr->starttime = jiffies;
        cqr->retries--;
        if (!test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags)) {
                cqr->lpm &= dasd_path_get_opm(device);
                if (!cqr->lpm)
                        cqr->lpm = dasd_path_get_opm(device);
        }
        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 -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 != dasd_path_get_opm(device)) {
                        cqr->lpm = dasd_path_get_opm(device);
                        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);
                        dasd_path_no_path(device);
                        dasd_path_set_tbvpm(device,
                                          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:
                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;
}
EXPORT_SYMBOL(dasd_start_IO);

/*
 * 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(struct timer_list *t)
{
        unsigned long flags;
        struct dasd_device *device;

        device = from_timer(device, t, timer);
        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);
}
EXPORT_SYMBOL(dasd_device_set_timer);

/*
 * Clear timeout for a device.
 */
void dasd_device_clear_timer(struct dasd_device *device)
{
        del_timer(&device->timer);
}
EXPORT_SYMBOL(dasd_device_clear_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);
                if (device->block->request_queue)
                        blk_mq_run_hw_queues(device->block->request_queue,
                                             true);
        }
}
EXPORT_SYMBOL_GPL(dasd_generic_handle_state_change);

static int dasd_check_hpf_error(struct irb *irb)
{
        return (scsw_tm_is_valid_schxs(&irb->scsw) &&
            (irb->scsw.tm.sesq == SCSW_SESQ_DEV_NOFCX ||
             irb->scsw.tm.sesq == SCSW_SESQ_PATH_NOFCX));
}

static int dasd_ese_needs_format(struct dasd_block *block, struct irb *irb)
{
        struct dasd_device *device = NULL;
        u8 *sense = NULL;

        if (!block)
                return 0;
        device = block->base;
        if (!device || !device->discipline->is_ese)
                return 0;
        if (!device->discipline->is_ese(device))
                return 0;

        sense = dasd_get_sense(irb);
        if (!sense)
                return 0;

        return !!(sense[1] & SNS1_NO_REC_FOUND) ||
                !!(sense[1] & SNS1_FILE_PROTECTED) ||
                scsw_cstat(&irb->scsw) == SCHN_STAT_INCORR_LEN;
}

static int dasd_ese_oos_cond(u8 *sense)
{
        return sense[0] & SNS0_EQUIPMENT_CHECK &&
                sense[1] & SNS1_PERM_ERR &&
                sense[1] & SNS1_WRITE_INHIBITED &&
                sense[25] == 0x01;
}

/*
 * 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, *fcqr;
        struct dasd_device *device;
        unsigned long now;
        int nrf_suppressed = 0;
        int fp_suppressed = 0;
        u8 *sense = NULL;
        int expires;

        cqr = (struct dasd_ccw_req *) intparm;
        if (IS_ERR(irb)) {
                switch (PTR_ERR(irb)) {
                case -EIO:
                        if (cqr && cqr->status == DASD_CQR_CLEAR_PENDING) {
                                device = cqr->startdev;
                                cqr->status = DASD_CQR_CLEARED;
                                dasd_device_clear_timer(device);
                                wake_up(&dasd_flush_wq);
                                dasd_schedule_device_bh(device);
                                return;
                        }
                        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_tod_clock();
        /* 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;
                }

                /*
                 * In some cases 'File Protected' or 'No Record Found' errors
                 * might be expected and debug log messages for the
                 * corresponding interrupts shouldn't be written then.
                 * Check if either of the according suppress bits is set.
                 */
                sense = dasd_get_sense(irb);
                if (sense) {
                        fp_suppressed = (sense[1] & SNS1_FILE_PROTECTED) &&
                                test_bit(DASD_CQR_SUPPRESS_FP, &cqr->flags);
                        nrf_suppressed = (sense[1] & SNS1_NO_REC_FOUND) &&
                                test_bit(DASD_CQR_SUPPRESS_NRF, &cqr->flags);

                        /*
                         * Extent pool probably out-of-space.
                         * Stop device and check exhaust level.
                         */
                        if (dasd_ese_oos_cond(sense)) {
                                dasd_generic_space_exhaust(device, cqr);
                                device->discipline->ext_pool_exhaust(device, cqr);
                                dasd_put_device(device);
                                return;
                        }
                }
                if (!(fp_suppressed || nrf_suppressed))
                        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);
        }

        /* check for for attention message */
        if (scsw_dstat(&irb->scsw) & DEV_STAT_ATTENTION) {
                device = dasd_device_from_cdev_locked(cdev);
                if (!IS_ERR(device)) {
                        device->discipline->check_attention(device,
                                                            irb->esw.esw1.lpum);
                        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;
        }

        if (dasd_ese_needs_format(cqr->block, irb)) {
                if (rq_data_dir((struct request *)cqr->callback_data) == READ) {
                        device->discipline->ese_read(cqr, irb);
                        cqr->status = DASD_CQR_SUCCESS;
                        cqr->stopclk = now;
                        dasd_device_clear_timer(device);
                        dasd_schedule_device_bh(device);
                        return;
                }
                fcqr = device->discipline->ese_format(device, cqr, irb);
                if (IS_ERR(fcqr)) {
                        if (PTR_ERR(fcqr) == -EINVAL) {
                                cqr->status = DASD_CQR_ERROR;
                                return;
                        }
                        /*
                         * If we can't format now, let the request go
                         * one extra round. Maybe we can format later.
                         */
                        cqr->status = DASD_CQR_QUEUED;
                        dasd_schedule_device_bh(device);
                        return;
                } else {
                        fcqr->status = DASD_CQR_QUEUED;
                        cqr->status = DASD_CQR_QUEUED;
                        list_add(&fcqr->devlist, &device->ccw_queue);
                        dasd_schedule_device_bh(device);
                        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 */
                /* check for HPF error
                 * call discipline function to requeue all requests
                 * and disable HPF accordingly
                 */
                if (cqr->cpmode && dasd_check_hpf_error(irb) &&
                    device->discipline->handle_hpf_error)
                        device->discipline->handle_hpf_error(device, irb);
                /*
                 * 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 == dasd_path_get_opm(device))
                                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 = dasd_path_get_opm(device);
                        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);
}
EXPORT_SYMBOL(dasd_int_handler);

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);

                /* Skip any non-final request. */
                if (cqr->status == DASD_CQR_QUEUED ||
                    cqr->status == DASD_CQR_IN_IO ||
                    cqr->status == DASD_CQR_CLEAR_PENDING)
                        continue;
                if (cqr->status == DASD_CQR_ERROR) {
                        __dasd_device_recovery(device, cqr);
                }
                /* Rechain finished requests to final queue */
                list_move_tail(&cqr->devlist, final_queue);
        }
}

static void __dasd_process_cqr(struct dasd_device *device,
                               struct dasd_ccw_req *cqr)
{
        char errorstring[ERRORLENGTH];

        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)
                cqr->callback(cqr, cqr->callback_data);
}

/*
 * 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;

        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;
                if (!block) {
                        __dasd_process_cqr(device, cqr);
                } else {
                        spin_lock_bh(&block->queue_lock);
                        __dasd_process_cqr(device, cqr);
                        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 (test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {
                        /*
                         * IO in safe offline processing should not
                         * run out of retries
                         */
                        cqr->retries++;
                }
                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);
                }

        }
}

/*
 * return 1 when device is not eligible for IO
 */
static int __dasd_device_is_unusable(struct dasd_device *device,
                                     struct dasd_ccw_req *cqr)
{
        int mask = ~(DASD_STOPPED_DC_WAIT | DASD_STOPPED_NOSPC);

        if (test_bit(DASD_FLAG_OFFLINE, &device->flags) &&
            !test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {
                /*
                 * dasd is being set offline
                 * but it is no safe offline where we have to allow I/O
                 */
                return 1;
        }
        if (device->stopped) {
                if (device->stopped & mask) {
                        /* stopped and CQR will not change that. */
                        return 1;
                }
                if (!test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags)) {
                        /* CQR is not able to change device to
                         * operational. */
                        return 1;
                }
                /* CQR required to get device operational. */
        }
        return 0;
}

/*
 * 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;
        /* if device is not usable return request to upper layer */
        if (__dasd_device_is_unusable(device, cqr)) {
                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)
{
        __u8 tbvpm, fcsecpm;
        int rc;

        tbvpm = dasd_path_get_tbvpm(device);
        fcsecpm = dasd_path_get_fcsecpm(device);

        if (!tbvpm && !fcsecpm)
                return;

        if (device->stopped & ~(DASD_STOPPED_DC_WAIT))
                return;
        rc = device->discipline->pe_handler(device, tbvpm, fcsecpm);
        if (rc) {
                dasd_device_set_timer(device, 50);
        } else {
                dasd_path_clear_all_verify(device);
                dasd_path_clear_all_fcsec(device);
        }
};

/*
 * 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_tod_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;
}
EXPORT_SYMBOL_GPL(dasd_flush_device_queue);

/*
 * Acquire the device lock and process queues for the device.
 */
static void dasd_device_tasklet(unsigned long data)
{
        struct dasd_device *device = (struct dasd_device *) data;
        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);
}
EXPORT_SYMBOL(dasd_schedule_device_bh);

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);
}
EXPORT_SYMBOL(dasd_add_request_head);

/*
 * 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);
}
EXPORT_SYMBOL(dasd_add_request_tail);

/*
 * 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 = -ENOLINK;
                        continue;
                }
                /*
                 * Don't try to start requests if device is in
                 * offline processing, it might wait forever
                 */
                if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {
                        cqr->status = DASD_CQR_FAILED;
                        cqr->intrc = -ENODEV;
                        continue;
                }
                /*
                 * Don't try to start requests if device is stopped
                 * except path verification requests
                 */
                if (!test_bit(DASD_CQR_VERIFY_PATH, &cqr->flags)) {
                        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_tod_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;
}

static inline int _wait_for_wakeup_queue(struct list_head *ccw_queue)
{
        struct dasd_ccw_req *cqr;

        list_for_each_entry(cqr, ccw_queue, blocklist) {
                if (cqr->callback_data != DASD_SLEEPON_END_TAG)
                        return 0;
        }

        return 1;
}

static int _dasd_sleep_on_queue(struct list_head *ccw_queue, int interruptible)
{
        struct dasd_device *device;
        struct dasd_ccw_req *cqr, *n;
        u8 *sense = NULL;
        int rc;

retry:
        list_for_each_entry_safe(cqr, n, ccw_queue, blocklist) {
                device = cqr->startdev;
                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;
                                cqr->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);
        }

        wait_event(generic_waitq, _wait_for_wakeup_queue(ccw_queue));

        rc = 0;
        list_for_each_entry_safe(cqr, n, ccw_queue, blocklist) {
                /*
                 * In some cases the 'File Protected' or 'Incorrect Length'
                 * error might be expected and error recovery would be
                 * unnecessary in these cases.  Check if the according suppress
                 * bit is set.
                 */
                sense = dasd_get_sense(&cqr->irb);
                if (sense && sense[1] & SNS1_FILE_PROTECTED &&
                    test_bit(DASD_CQR_SUPPRESS_FP, &cqr->flags))
                        continue;
                if (scsw_cstat(&cqr->irb.scsw) == 0x40 &&
                    test_bit(DASD_CQR_SUPPRESS_IL, &cqr->flags))
                        continue;

                /*
                 * for alias devices simplify error recovery and
                 * return to upper layer
                 * do not skip ERP requests
                 */
                if (cqr->startdev != cqr->basedev && !cqr->refers &&
                    (cqr->status == DASD_CQR_TERMINATED ||
                     cqr->status == DASD_CQR_NEED_ERP))
                        return -EAGAIN;

                /* normal recovery for basedev IO */
                if (__dasd_sleep_on_erp(cqr))
                        /* handle erp first */
                        goto retry;
        }

        return 0;
}

/*
 * 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);
}
EXPORT_SYMBOL(dasd_sleep_on);

/*
 * Start requests from a ccw_queue and wait for their completion.
 */
int dasd_sleep_on_queue(struct list_head *ccw_queue)
{
        return _dasd_sleep_on_queue(ccw_queue, 0);
}
EXPORT_SYMBOL(dasd_sleep_on_queue);

/*
 * Start requests from a ccw_queue and wait interruptible for their completion.
 */
int dasd_sleep_on_queue_interruptible(struct list_head *ccw_queue)
{
        return _dasd_sleep_on_queue(ccw_queue, 1);
}
EXPORT_SYMBOL(dasd_sleep_on_queue_interruptible);

/*
 * 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);
}
EXPORT_SYMBOL(dasd_sleep_on_interruptible);

/*
 * 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;

        /* kick tasklets */
        dasd_schedule_device_bh(device);
        if (device->block)
                dasd_schedule_block_bh(device->block);

        return rc;
}
EXPORT_SYMBOL(dasd_sleep_on_immediatly);

/*
 * 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 0 if request termination was successful
 *         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.
 */
static int __dasd_cancel_req(struct dasd_ccw_req *cqr)
{
        struct dasd_device *device = cqr->startdev;
        int rc = 0;

        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_tod_clock();
                }
                break;
        default: /* already finished or clear pending - do nothing */
                break;
        }
        dasd_schedule_device_bh(device);
        return rc;
}

int dasd_cancel_req(struct dasd_ccw_req *cqr)
{
        struct dasd_device *device = cqr->startdev;
        unsigned long flags;
        int rc;

        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
        rc = __dasd_cancel_req(cqr);
        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
        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(struct timer_list *t)
{
        unsigned long flags;
        struct dasd_block *block;

        block = from_timer(block, t, timer);
        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);
        blk_mq_run_hw_queues(block->request_queue, true);
}

/*
 * 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);
}
EXPORT_SYMBOL(dasd_block_set_timer);

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

static void __dasd_cleanup_cqr(struct dasd_ccw_req *cqr)
{
        struct request *req;
        blk_status_t error = BLK_STS_OK;
        unsigned int proc_bytes;
        int status;

        req = (struct request *) cqr->callback_data;
        dasd_profile_end(cqr->block, cqr, req);

        proc_bytes = cqr->proc_bytes;
        status = cqr->block->base->discipline->free_cp(cqr, req);
        if (status < 0)
                error = errno_to_blk_status(status);
        else if (status == 0) {
                switch (cqr->intrc) {
                case -EPERM:
                        error = BLK_STS_NEXUS;
                        break;
                case -ENOLINK:
                        error = BLK_STS_TRANSPORT;
                        break;
                case -ETIMEDOUT:
                        error = BLK_STS_TIMEOUT;
                        break;
                default:
                        error = BLK_STS_IOERR;
                        break;
                }
        }

        /*
         * We need to take care for ETIMEDOUT errors here since the
         * complete callback does not get called in this case.
         * Take care of all errors here and avoid additional code to
         * transfer the error value to the complete callback.
         */
        if (error) {
                blk_mq_end_request(req, error);
                blk_mq_run_hw_queues(req->q, true);
        } else {
                /*
                 * Partial completed requests can happen with ESE devices.
                 * During read we might have gotten a NRF error and have to
                 * complete a request partially.
                 */
                if (proc_bytes) {
                        blk_update_request(req, BLK_STS_OK,
                                           blk_rq_bytes(req) - proc_bytes);
                        blk_mq_requeue_request(req, true);
                } else if (likely(!blk_should_fake_timeout(req->q))) {
                        blk_mq_complete_request(req);
                }
        }
}

/*
 * 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_tod_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;
                        cqr->intrc = -ENOLINK;
                        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(unsigned long data)
{
        struct dasd_block *block = (struct dasd_block *) data;
        struct list_head final_queue;
        struct list_head *l, *n;
        struct dasd_ccw_req *cqr;
        struct dasd_queue *dq;

        atomic_set(&block->tasklet_scheduled, 0);
        INIT_LIST_HEAD(&final_queue);
        spin_lock_irq(&block->queue_lock);
        /* Finish off requests on ccw queue */
        __dasd_process_block_ccw_queue(block, &final_queue);
        spin_unlock_irq(&block->queue_lock);

        /* Now call the callback function of requests with final status */
        list_for_each_safe(l, n, &final_queue) {
                cqr = list_entry(l, struct dasd_ccw_req, blocklist);
                dq = cqr->dq;
                spin_lock_irq(&dq->lock);
                list_del_init(&cqr->blocklist);
                __dasd_cleanup_cqr(cqr);
                spin_unlock_irq(&dq->lock);
        }

        spin_lock_irq(&block->queue_lock);
        /* Now check if the head of the ccw queue needs to be started. */
        __dasd_block_start_head(block);
        spin_unlock_irq(&block->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);
}

/*
 * Requeue a request back to the block request queue
 * only works for block requests
 */
static int _dasd_requeue_request(struct dasd_ccw_req *cqr)
{
        struct dasd_block *block = cqr->block;
        struct request *req;

        if (!block)
                return -EINVAL;
        /*
         * If the request is an ERP request there is nothing to requeue.
         * This will be done with the remaining original request.
         */
        if (cqr->refers)
                return 0;
        spin_lock_irq(&cqr->dq->lock);
        req = (struct request *) cqr->callback_data;
        blk_mq_requeue_request(req, false);
        spin_unlock_irq(&cqr->dq->lock);

        return 0;
}

/*
 * 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;
        unsigned long flags;

        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) {