pktcdvd.c

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/*
 * Copyright (C) 2000 Jens Axboe <[email protected]>
 * Copyright (C) 2001-2004 Peter Osterlund <[email protected]>
 * Copyright (C) 2006 Thomas Maier <[email protected]>
 *
 * May be copied or modified under the terms of the GNU General Public
 * License.  See linux/COPYING for more information.
 *
 * Packet writing layer for ATAPI and SCSI CD-RW, DVD+RW, DVD-RW and
 * DVD-RAM devices.
 *
 * Theory of operation:
 *
 * At the lowest level, there is the standard driver for the CD/DVD device,
 * typically ide-cd.c or sr.c. This driver can handle read and write requests,
 * but it doesn't know anything about the special restrictions that apply to
 * packet writing. One restriction is that write requests must be aligned to
 * packet boundaries on the physical media, and the size of a write request
 * must be equal to the packet size. Another restriction is that a
 * GPCMD_FLUSH_CACHE command has to be issued to the drive before a read
 * command, if the previous command was a write.
 *
 * The purpose of the packet writing driver is to hide these restrictions from
 * higher layers, such as file systems, and present a block device that can be
 * randomly read and written using 2kB-sized blocks.
 *
 * The lowest layer in the packet writing driver is the packet I/O scheduler.
 * Its data is defined by the struct packet_iosched and includes two bio
 * queues with pending read and write requests. These queues are processed
 * by the pkt_iosched_process_queue() function. The write requests in this
 * queue are already properly aligned and sized. This layer is responsible for
 * issuing the flush cache commands and scheduling the I/O in a good order.
 *
 * The next layer transforms unaligned write requests to aligned writes. This
 * transformation requires reading missing pieces of data from the underlying
 * block device, assembling the pieces to full packets and queuing them to the
 * packet I/O scheduler.
 *
 * At the top layer there is a custom make_request_fn function that forwards
 * read requests directly to the iosched queue and puts write requests in the
 * unaligned write queue. A kernel thread performs the necessary read
 * gathering to convert the unaligned writes to aligned writes and then feeds
 * them to the packet I/O scheduler.
 *
 *************************************************************************/

#include <linux/pktcdvd.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/compat.h>
#include <linux/kthread.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/file.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/miscdevice.h>
#include <linux/freezer.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi.h>
#include <linux/debugfs.h>
#include <linux/device.h>

#include <asm/uaccess.h>

#define DRIVER_NAME "pktcdvd"

#if PACKET_DEBUG
#define DPRINTK(fmt, args...) printk(KERN_NOTICE fmt, ##args)
#else
#define DPRINTK(fmt, args...)
#endif

#if PACKET_DEBUG > 1
#define VPRINTK(fmt, args...) printk(KERN_NOTICE fmt, ##args)
#else
#define VPRINTK(fmt, args...)
#endif

#define MAX_SPEED 0xffff

#define ZONE(sector, pd) (((sector) + (pd)->offset) & ~((pd)->settings.size - 1))

static DEFINE_MUTEX(pktcdvd_mutex);
static struct pktcdvd_device *pkt_devs[MAX_WRITERS];
static struct proc_dir_entry *pkt_proc;
static int pktdev_major;
static int write_congestion_on  = PKT_WRITE_CONGESTION_ON;
static int write_congestion_off = PKT_WRITE_CONGESTION_OFF;
static struct mutex ctl_mutex;  /* Serialize open/close/setup/teardown */
static mempool_t *psd_pool;

static struct class *class_pktcdvd = NULL;    /* /sys/class/pktcdvd */
static struct dentry    *pkt_debugfs_root = NULL; /* /sys/kernel/debug/pktcdvd */

/* forward declaration */
static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev);
static int pkt_remove_dev(dev_t pkt_dev);
static int pkt_seq_show(struct seq_file *m, void *p);



/*
 * create and register a pktcdvd kernel object.
 */
static struct pktcdvd_kobj* pkt_kobj_create(struct pktcdvd_device *pd,
                    const char* name,
                    struct kobject* parent,
                    struct kobj_type* ktype)
{
    struct pktcdvd_kobj *p;
    int error;

    p = kzalloc(sizeof(*p), GFP_KERNEL);
    if (!p)
        return NULL;
    p->pd = pd;
    error = kobject_init_and_add(&p->kobj, ktype, parent, "%s", name);
    if (error) {
        kobject_put(&p->kobj);
        return NULL;
    }
    kobject_uevent(&p->kobj, KOBJ_ADD);
    return p;
}
/*
 * remove a pktcdvd kernel object.
 */
static void pkt_kobj_remove(struct pktcdvd_kobj *p)
{
    if (p)
        kobject_put(&p->kobj);
}
/*
 * default release function for pktcdvd kernel objects.
 */
static void pkt_kobj_release(struct kobject *kobj)
{
    kfree(to_pktcdvdkobj(kobj));
}


/**********************************************************
 *
 * sysfs interface for pktcdvd
 * by (C) 2006  Thomas Maier <[email protected]>
 *
 **********************************************************/

#define DEF_ATTR(_obj,_name,_mode) \
    static struct attribute _obj = { .name = _name, .mode = _mode }

/**********************************************************
  /sys/class/pktcdvd/pktcdvd[0-7]/
                     stat/reset
                     stat/packets_started
                     stat/packets_finished
                     stat/kb_written
                     stat/kb_read
                     stat/kb_read_gather
                     write_queue/size
                     write_queue/congestion_off
                     write_queue/congestion_on
 **********************************************************/

DEF_ATTR(kobj_pkt_attr_st1, "reset", 0200);
DEF_ATTR(kobj_pkt_attr_st2, "packets_started", 0444);
DEF_ATTR(kobj_pkt_attr_st3, "packets_finished", 0444);
DEF_ATTR(kobj_pkt_attr_st4, "kb_written", 0444);
DEF_ATTR(kobj_pkt_attr_st5, "kb_read", 0444);
DEF_ATTR(kobj_pkt_attr_st6, "kb_read_gather", 0444);

static struct attribute *kobj_pkt_attrs_stat[] = {
    &kobj_pkt_attr_st1,
    &kobj_pkt_attr_st2,
    &kobj_pkt_attr_st3,
    &kobj_pkt_attr_st4,
    &kobj_pkt_attr_st5,
    &kobj_pkt_attr_st6,
    NULL
};

DEF_ATTR(kobj_pkt_attr_wq1, "size", 0444);
DEF_ATTR(kobj_pkt_attr_wq2, "congestion_off", 0644);
DEF_ATTR(kobj_pkt_attr_wq3, "congestion_on",  0644);

static struct attribute *kobj_pkt_attrs_wqueue[] = {
    &kobj_pkt_attr_wq1,
    &kobj_pkt_attr_wq2,
    &kobj_pkt_attr_wq3,
    NULL
};

static ssize_t kobj_pkt_show(struct kobject *kobj,
            struct attribute *attr, char *data)
{
    struct pktcdvd_device *pd = to_pktcdvdkobj(kobj)->pd;
    int n = 0;
    int v;
    if (strcmp(attr->name, "packets_started") == 0) {
        n = sprintf(data, "%lu\n", pd->stats.pkt_started);

    } else if (strcmp(attr->name, "packets_finished") == 0) {
        n = sprintf(data, "%lu\n", pd->stats.pkt_ended);

    } else if (strcmp(attr->name, "kb_written") == 0) {
        n = sprintf(data, "%lu\n", pd->stats.secs_w >> 1);

    } else if (strcmp(attr->name, "kb_read") == 0) {
        n = sprintf(data, "%lu\n", pd->stats.secs_r >> 1);

    } else if (strcmp(attr->name, "kb_read_gather") == 0) {
        n = sprintf(data, "%lu\n", pd->stats.secs_rg >> 1);

    } else if (strcmp(attr->name, "size") == 0) {
        spin_lock(&pd->lock);
        v = pd->bio_queue_size;
        spin_unlock(&pd->lock);
        n = sprintf(data, "%d\n", v);

    } else if (strcmp(attr->name, "congestion_off") == 0) {
        spin_lock(&pd->lock);
        v = pd->write_congestion_off;
        spin_unlock(&pd->lock);
        n = sprintf(data, "%d\n", v);

    } else if (strcmp(attr->name, "congestion_on") == 0) {
        spin_lock(&pd->lock);
        v = pd->write_congestion_on;
        spin_unlock(&pd->lock);
        n = sprintf(data, "%d\n", v);
    }
    return n;
}

static void init_write_congestion_marks(int* lo, int* hi)
{
    if (*hi > 0) {
        *hi = max(*hi, 500);
        *hi = min(*hi, 1000000);
        if (*lo <= 0)
            *lo = *hi - 100;
        else {
            *lo = min(*lo, *hi - 100);
            *lo = max(*lo, 100);
        }
    } else {
        *hi = -1;
        *lo = -1;
    }
}

static ssize_t kobj_pkt_store(struct kobject *kobj,
            struct attribute *attr,
            const char *data, size_t len)
{
    struct pktcdvd_device *pd = to_pktcdvdkobj(kobj)->pd;
    int val;

    if (strcmp(attr->name, "reset") == 0 && len > 0) {
        pd->stats.pkt_started = 0;
        pd->stats.pkt_ended = 0;
        pd->stats.secs_w = 0;
        pd->stats.secs_rg = 0;
        pd->stats.secs_r = 0;

    } else if (strcmp(attr->name, "congestion_off") == 0
           && sscanf(data, "%d", &val) == 1) {
        spin_lock(&pd->lock);
        pd->write_congestion_off = val;
        init_write_congestion_marks(&pd->write_congestion_off,
                    &pd->write_congestion_on);
        spin_unlock(&pd->lock);

    } else if (strcmp(attr->name, "congestion_on") == 0
           && sscanf(data, "%d", &val) == 1) {
        spin_lock(&pd->lock);
        pd->write_congestion_on = val;
        init_write_congestion_marks(&pd->write_congestion_off,
                    &pd->write_congestion_on);
        spin_unlock(&pd->lock);
    }
    return len;
}

static const struct sysfs_ops kobj_pkt_ops = {
    .show = kobj_pkt_show,
    .store = kobj_pkt_store
};
static struct kobj_type kobj_pkt_type_stat = {
    .release = pkt_kobj_release,
    .sysfs_ops = &kobj_pkt_ops,
    .default_attrs = kobj_pkt_attrs_stat
};
static struct kobj_type kobj_pkt_type_wqueue = {
    .release = pkt_kobj_release,
    .sysfs_ops = &kobj_pkt_ops,
    .default_attrs = kobj_pkt_attrs_wqueue
};

static void pkt_sysfs_dev_new(struct pktcdvd_device *pd)
{
    if (class_pktcdvd) {
        pd->dev = device_create(class_pktcdvd, NULL, MKDEV(0, 0), NULL,
                    "%s", pd->name);
        if (IS_ERR(pd->dev))
            pd->dev = NULL;
    }
    if (pd->dev) {
        pd->kobj_stat = pkt_kobj_create(pd, "stat",
                    &pd->dev->kobj,
                    &kobj_pkt_type_stat);
        pd->kobj_wqueue = pkt_kobj_create(pd, "write_queue",
                    &pd->dev->kobj,
                    &kobj_pkt_type_wqueue);
    }
}

static void pkt_sysfs_dev_remove(struct pktcdvd_device *pd)
{
    pkt_kobj_remove(pd->kobj_stat);
    pkt_kobj_remove(pd->kobj_wqueue);
    if (class_pktcdvd)
        device_unregister(pd->dev);
}


/********************************************************************
  /sys/class/pktcdvd/
                     add            map block device
                     remove         unmap packet dev
                     device_map     show mappings
 *******************************************************************/

static void class_pktcdvd_release(struct class *cls)
{
    kfree(cls);
}
static ssize_t class_pktcdvd_show_map(struct class *c,
                    struct class_attribute *attr,
                    char *data)
{
    int n = 0;
    int idx;
    mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
    for (idx = 0; idx < MAX_WRITERS; idx++) {
        struct pktcdvd_device *pd = pkt_devs[idx];
        if (!pd)
            continue;
        n += sprintf(data+n, "%s %u:%u %u:%u\n",
            pd->name,
            MAJOR(pd->pkt_dev), MINOR(pd->pkt_dev),
            MAJOR(pd->bdev->bd_dev),
            MINOR(pd->bdev->bd_dev));
    }
    mutex_unlock(&ctl_mutex);
    return n;
}

static ssize_t class_pktcdvd_store_add(struct class *c,
                    struct class_attribute *attr,
                    const char *buf,
                    size_t count)
{
    unsigned int major, minor;

    if (sscanf(buf, "%u:%u", &major, &minor) == 2) {
        /* pkt_setup_dev() expects caller to hold reference to self */
        if (!try_module_get(THIS_MODULE))
            return -ENODEV;

        pkt_setup_dev(MKDEV(major, minor), NULL);

        module_put(THIS_MODULE);

        return count;
    }

    return -EINVAL;
}

static ssize_t class_pktcdvd_store_remove(struct class *c,
                      struct class_attribute *attr,
                      const char *buf,
                    size_t count)
{
    unsigned int major, minor;
    if (sscanf(buf, "%u:%u", &major, &minor) == 2) {
        pkt_remove_dev(MKDEV(major, minor));
        return count;
    }
    return -EINVAL;
}

static struct class_attribute class_pktcdvd_attrs[] = {
 __ATTR(add,            0200, NULL, class_pktcdvd_store_add),
 __ATTR(remove,         0200, NULL, class_pktcdvd_store_remove),
 __ATTR(device_map,     0444, class_pktcdvd_show_map, NULL),
 __ATTR_NULL
};


static int pkt_sysfs_init(void)
{
    int ret = 0;

    /*
     * create control files in sysfs
     * /sys/class/pktcdvd/...
     */
    class_pktcdvd = kzalloc(sizeof(*class_pktcdvd), GFP_KERNEL);
    if (!class_pktcdvd)
        return -ENOMEM;
    class_pktcdvd->name = DRIVER_NAME;
    class_pktcdvd->owner = THIS_MODULE;
    class_pktcdvd->class_release = class_pktcdvd_release;
    class_pktcdvd->class_attrs = class_pktcdvd_attrs;
    ret = class_register(class_pktcdvd);
    if (ret) {
        kfree(class_pktcdvd);
        class_pktcdvd = NULL;
        printk(DRIVER_NAME": failed to create class pktcdvd\n");
        return ret;
    }
    return 0;
}

static void pkt_sysfs_cleanup(void)
{
    if (class_pktcdvd)
        class_destroy(class_pktcdvd);
    class_pktcdvd = NULL;
}

/********************************************************************
  entries in debugfs

  /sys/kernel/debug/pktcdvd[0-7]/
            info

 *******************************************************************/

static int pkt_debugfs_seq_show(struct seq_file *m, void *p)
{
    return pkt_seq_show(m, p);
}

static int pkt_debugfs_fops_open(struct inode *inode, struct file *file)
{
    return single_open(file, pkt_debugfs_seq_show, inode->i_private);
}

static const struct file_operations debug_fops = {
    .open       = pkt_debugfs_fops_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
    .owner      = THIS_MODULE,
};

static void pkt_debugfs_dev_new(struct pktcdvd_device *pd)
{
    if (!pkt_debugfs_root)
        return;
    pd->dfs_f_info = NULL;
    pd->dfs_d_root = debugfs_create_dir(pd->name, pkt_debugfs_root);
    if (IS_ERR(pd->dfs_d_root)) {
        pd->dfs_d_root = NULL;
        return;
    }
    pd->dfs_f_info = debugfs_create_file("info", S_IRUGO,
                pd->dfs_d_root, pd, &debug_fops);
    if (IS_ERR(pd->dfs_f_info)) {
        pd->dfs_f_info = NULL;
        return;
    }
}

static void pkt_debugfs_dev_remove(struct pktcdvd_device *pd)
{
    if (!pkt_debugfs_root)
        return;
    if (pd->dfs_f_info)
        debugfs_remove(pd->dfs_f_info);
    pd->dfs_f_info = NULL;
    if (pd->dfs_d_root)
        debugfs_remove(pd->dfs_d_root);
    pd->dfs_d_root = NULL;
}

static void pkt_debugfs_init(void)
{
    pkt_debugfs_root = debugfs_create_dir(DRIVER_NAME, NULL);
    if (IS_ERR(pkt_debugfs_root)) {
        pkt_debugfs_root = NULL;
        return;
    }
}

static void pkt_debugfs_cleanup(void)
{
    if (!pkt_debugfs_root)
        return;
    debugfs_remove(pkt_debugfs_root);
    pkt_debugfs_root = NULL;
}

/* ----------------------------------------------------------*/


static void pkt_bio_finished(struct pktcdvd_device *pd)
{
    BUG_ON(atomic_read(&pd->cdrw.pending_bios) <= 0);
    if (atomic_dec_and_test(&pd->cdrw.pending_bios)) {
        VPRINTK(DRIVER_NAME": queue empty\n");
        atomic_set(&pd->iosched.attention, 1);
        wake_up(&pd->wqueue);
    }
}

/*
 * Allocate a packet_data struct
 */
static struct packet_data *pkt_alloc_packet_data(int frames)
{
    int i;
    struct packet_data *pkt;

    pkt = kzalloc(sizeof(struct packet_data), GFP_KERNEL);
    if (!pkt)
        goto no_pkt;

    pkt->frames = frames;
    pkt->w_bio = bio_kmalloc(GFP_KERNEL, frames);
    if (!pkt->w_bio)
        goto no_bio;

    for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
        pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
        if (!pkt->pages[i])
            goto no_page;
    }

    spin_lock_init(&pkt->lock);
    bio_list_init(&pkt->orig_bios);

    for (i = 0; i < frames; i++) {
        struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);
        if (!bio)
            goto no_rd_bio;

        pkt->r_bios[i] = bio;
    }

    return pkt;

no_rd_bio:
    for (i = 0; i < frames; i++) {
        struct bio *bio = pkt->r_bios[i];
        if (bio)
            bio_put(bio);
    }

no_page:
    for (i = 0; i < frames / FRAMES_PER_PAGE; i++)
        if (pkt->pages[i])
            __free_page(pkt->pages[i]);
    bio_put(pkt->w_bio);
no_bio:
    kfree(pkt);
no_pkt:
    return NULL;
}

/*
 * Free a packet_data struct
 */
static void pkt_free_packet_data(struct packet_data *pkt)
{
    int i;

    for (i = 0; i < pkt->frames; i++) {
        struct bio *bio = pkt->r_bios[i];
        if (bio)
            bio_put(bio);
    }
    for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)
        __free_page(pkt->pages[i]);
    bio_put(pkt->w_bio);
    kfree(pkt);
}

static void pkt_shrink_pktlist(struct pktcdvd_device *pd)
{
    struct packet_data *pkt, *next;

    BUG_ON(!list_empty(&pd->cdrw.pkt_active_list));

    list_for_each_entry_safe(pkt, next, &pd->cdrw.pkt_free_list, list) {
        pkt_free_packet_data(pkt);
    }
    INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
}

static int pkt_grow_pktlist(struct pktcdvd_device *pd, int nr_packets)
{
    struct packet_data *pkt;

    BUG_ON(!list_empty(&pd->cdrw.pkt_free_list));

    while (nr_packets > 0) {
        pkt = pkt_alloc_packet_data(pd->settings.size >> 2);
        if (!pkt) {
            pkt_shrink_pktlist(pd);
            return 0;
        }
        pkt->id = nr_packets;
        pkt->pd = pd;
        list_add(&pkt->list, &pd->cdrw.pkt_free_list);
        nr_packets--;
    }
    return 1;
}

static inline struct pkt_rb_node *pkt_rbtree_next(struct pkt_rb_node *node)
{
    struct rb_node *n = rb_next(&node->rb_node);
    if (!n)
        return NULL;
    return rb_entry(n, struct pkt_rb_node, rb_node);
}

static void pkt_rbtree_erase(struct pktcdvd_device *pd, struct pkt_rb_node *node)
{
    rb_erase(&node->rb_node, &pd->bio_queue);
    mempool_free(node, pd->rb_pool);
    pd->bio_queue_size--;
    BUG_ON(pd->bio_queue_size < 0);
}

/*
 * Find the first node in the pd->bio_queue rb tree with a starting sector >= s.
 */
static struct pkt_rb_node *pkt_rbtree_find(struct pktcdvd_device *pd, sector_t s)
{
    struct rb_node *n = pd->bio_queue.rb_node;
    struct rb_node *next;
    struct pkt_rb_node *tmp;

    if (!n) {
        BUG_ON(pd->bio_queue_size > 0);
        return NULL;
    }

    for (;;) {
        tmp = rb_entry(n, struct pkt_rb_node, rb_node);
        if (s <= tmp->bio->bi_sector)
            next = n->rb_left;
        else
            next = n->rb_right;
        if (!next)
            break;
        n = next;
    }

    if (s > tmp->bio->bi_sector) {
        tmp = pkt_rbtree_next(tmp);
        if (!tmp)
            return NULL;
    }
    BUG_ON(s > tmp->bio->bi_sector);
    return tmp;
}

/*
 * Insert a node into the pd->bio_queue rb tree.
 */
static void pkt_rbtree_insert(struct pktcdvd_device *pd, struct pkt_rb_node *node)
{
    struct rb_node **p = &pd->bio_queue.rb_node;
    struct rb_node *parent = NULL;
    sector_t s = node->bio->bi_sector;
    struct pkt_rb_node *tmp;

    while (*p) {
        parent = *p;
        tmp = rb_entry(parent, struct pkt_rb_node, rb_node);
        if (s < tmp->bio->bi_sector)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }
    rb_link_node(&node->rb_node, parent, p);
    rb_insert_color(&node->rb_node, &pd->bio_queue);
    pd->bio_queue_size++;
}

/*
 * Send a packet_command to the underlying block device and
 * wait for completion.
 */
static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *cgc)
{
    struct request_queue *q = bdev_get_queue(pd->bdev);
    struct request *rq;
    int ret = 0;

    rq = blk_get_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
                 WRITE : READ, __GFP_WAIT);

    if (cgc->buflen) {
        if (blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen, __GFP_WAIT))
            goto out;
    }

    rq->cmd_len = COMMAND_SIZE(cgc->cmd[0]);
    memcpy(rq->cmd, cgc->cmd, CDROM_PACKET_SIZE);

    rq->timeout = 60*HZ;
    rq->cmd_type = REQ_TYPE_BLOCK_PC;
    if (cgc->quiet)
        rq->cmd_flags |= REQ_QUIET;

    blk_execute_rq(rq->q, pd->bdev->bd_disk, rq, 0);
    if (rq->errors)
        ret = -EIO;
out:
    blk_put_request(rq);
    return ret;
}

/*
 * A generic sense dump / resolve mechanism should be implemented across
 * all ATAPI + SCSI devices.
 */
static void pkt_dump_sense(struct packet_command *cgc)
{
    static char *info[9] = { "No sense", "Recovered error", "Not ready",
                 "Medium error", "Hardware error", "Illegal request",
                 "Unit attention", "Data protect", "Blank check" };
    int i;
    struct request_sense *sense = cgc->sense;

    printk(DRIVER_NAME":");
    for (i = 0; i < CDROM_PACKET_SIZE; i++)
        printk(" %02x", cgc->cmd[i]);
    printk(" - ");

    if (sense == NULL) {
        printk("no sense\n");
        return;
    }

    printk("sense %02x.%02x.%02x", sense->sense_key, sense->asc, sense->ascq);

    if (sense->sense_key > 8) {
        printk(" (INVALID)\n");
        return;
    }

    printk(" (%s)\n", info[sense->sense_key]);
}

/*
 * flush the drive cache to media
 */
static int pkt_flush_cache(struct pktcdvd_device *pd)
{
    struct packet_command cgc;

    init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
    cgc.cmd[0] = GPCMD_FLUSH_CACHE;
    cgc.quiet = 1;

    /*
     * the IMMED bit -- we default to not setting it, although that
     * would allow a much faster close, this is safer
     */
#if 0
    cgc.cmd[1] = 1 << 1;
#endif
    return pkt_generic_packet(pd, &cgc);
}

/*
 * speed is given as the normal factor, e.g. 4 for 4x
 */
static noinline_for_stack int pkt_set_speed(struct pktcdvd_device *pd,
                unsigned write_speed, unsigned read_speed)
{
    struct packet_command cgc;
    struct request_sense sense;
    int ret;

    init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
    cgc.sense = &sense;
    cgc.cmd[0] = GPCMD_SET_SPEED;
    cgc.cmd[2] = (read_speed >> 8) & 0xff;
    cgc.cmd[3] = read_speed & 0xff;
    cgc.cmd[4] = (write_speed >> 8) & 0xff;
    cgc.cmd[5] = write_speed & 0xff;

    if ((ret = pkt_generic_packet(pd, &cgc)))
        pkt_dump_sense(&cgc);

    return ret;
}

/*
 * Queue a bio for processing by the low-level CD device. Must be called
 * from process context.
 */
static void pkt_queue_bio(struct pktcdvd_device *pd, struct bio *bio)
{
    spin_lock(&pd->iosched.lock);
    if (bio_data_dir(bio) == READ)
        bio_list_add(&pd->iosched.read_queue, bio);
    else
        bio_list_add(&pd->iosched.write_queue, bio);
    spin_unlock(&pd->iosched.lock);

    atomic_set(&pd->iosched.attention, 1);
    wake_up(&pd->wqueue);
}

/*
 * Process the queued read/write requests. This function handles special
 * requirements for CDRW drives:
 * - A cache flush command must be inserted before a read request if the
 *   previous request was a write.
 * - Switching between reading and writing is slow, so don't do it more often
 *   than necessary.
 * - Optimize for throughput at the expense of latency. This means that streaming
 *   writes will never be interrupted by a read, but if the drive has to seek
 *   before the next write, switch to reading instead if there are any pending
 *   read requests.
 * - Set the read speed according to current usage pattern. When only reading
 *   from the device, it's best to use the highest possible read speed, but
 *   when switching often between reading and writing, it's better to have the
 *   same read and write speeds.
 */
static void pkt_iosched_process_queue(struct pktcdvd_device *pd)
{

    if (atomic_read(&pd->iosched.attention) == 0)
        return;
    atomic_set(&pd->iosched.attention, 0);

    for (;;) {
        struct bio *bio;
        int reads_queued, writes_queued;

        spin_lock(&pd->iosched.lock);
        reads_queued = !bio_list_empty(&pd->iosched.read_queue);
        writes_queued = !bio_list_empty(&pd->iosched.write_queue);
        spin_unlock(&pd->iosched.lock);

        if (!reads_queued && !writes_queued)
            break;

        if (pd->iosched.writing) {
            int need_write_seek = 1;
            spin_lock(&pd->iosched.lock);
            bio = bio_list_peek(&pd->iosched.write_queue);
            spin_unlock(&pd->iosched.lock);
            if (bio && (bio->bi_sector == pd->iosched.last_write))
                need_write_seek = 0;
            if (need_write_seek && reads_queued) {
                if (atomic_read(&pd->cdrw.pending_bios) > 0) {
                    VPRINTK(DRIVER_NAME": write, waiting\n");
                    break;
                }
                pkt_flush_cache(pd);
                pd->iosched.writing = 0;
            }
        } else {
            if (!reads_queued && writes_queued) {
                if (atomic_read(&pd->cdrw.pending_bios) > 0) {
                    VPRINTK(DRIVER_NAME": read, waiting\n");
                    break;
                }
                pd->iosched.writing = 1;
            }
        }

        spin_lock(&pd->iosched.lock);
        if (pd->iosched.writing)
            bio = bio_list_pop(&pd->iosched.write_queue);
        else
            bio = bio_list_pop(&pd->iosched.read_queue);
        spin_unlock(&pd->iosched.lock);

        if (!bio)
            continue;

        if (bio_data_dir(bio) == READ)
            pd->iosched.successive_reads += bio->bi_size >> 10;
        else {
            pd->iosched.successive_reads = 0;
            pd->iosched.last_write = bio->bi_sector + bio_sectors(bio);
        }
        if (pd->iosched.successive_reads >= HI_SPEED_SWITCH) {
            if (pd->read_speed == pd->write_speed) {
                pd->read_speed = MAX_SPEED;
                pkt_set_speed(pd, pd->write_speed, pd->read_speed);
            }
        } else {
            if (pd->read_speed != pd->write_speed) {
                pd->read_speed = pd->write_speed;
                pkt_set_speed(pd, pd->write_speed, pd->read_speed);
            }
        }

        atomic_inc(&pd->cdrw.pending_bios);
        generic_make_request(bio);
    }
}

/*
 * Special care is needed if the underlying block device has a small
 * max_phys_segments value.
 */
static int pkt_set_segment_merging(struct pktcdvd_device *pd, struct request_queue *q)
{
    if ((pd->settings.size << 9) / CD_FRAMESIZE
        <= queue_max_segments(q)) {
        /*
         * The cdrom device can handle one segment/frame
         */
        clear_bit(PACKET_MERGE_SEGS, &pd->flags);
        return 0;
    } else if ((pd->settings.size << 9) / PAGE_SIZE
           <= queue_max_segments(q)) {
        /*
         * We can handle this case at the expense of some extra memory
         * copies during write operations
         */
        set_bit(PACKET_MERGE_SEGS, &pd->flags);
        return 0;
    } else {
        printk(DRIVER_NAME": cdrom max_phys_segments too small\n");
        return -EIO;
    }
}

/*
 * Copy CD_FRAMESIZE bytes from src_bio into a destination page
 */
static void pkt_copy_bio_data(struct bio *src_bio, int seg, int offs, struct page *dst_page, int dst_offs)
{
    unsigned int copy_size = CD_FRAMESIZE;

    while (copy_size > 0) {
        struct bio_vec *src_bvl = bio_iovec_idx(src_bio, seg);
        void *vfrom = kmap_atomic(src_bvl->bv_page) +
            src_bvl->bv_offset + offs;
        void *vto = page_address(dst_page) + dst_offs;
        int len = min_t(int, copy_size, src_bvl->bv_len - offs);

        BUG_ON(len < 0);
        memcpy(vto, vfrom, len);
        kunmap_atomic(vfrom);

        seg++;
        offs = 0;
        dst_offs += len;
        copy_size -= len;
    }
}

/*
 * Copy all data for this packet to pkt->pages[], so that
 * a) The number of required segments for the write bio is minimized, which
 *    is necessary for some scsi controllers.
 * b) The data can be used as cache to avoid read requests if we receive a
 *    new write request for the same zone.
 */
static void pkt_make_local_copy(struct packet_data *pkt, struct bio_vec *bvec)
{
    int f, p, offs;

    /* Copy all data to pkt->pages[] */
    p = 0;
    offs = 0;
    for (f = 0; f < pkt->frames; f++) {
        if (bvec[f].bv_page != pkt->pages[p]) {
            void *vfrom = kmap_atomic(bvec[f].bv_page) + bvec[f].bv_offset;
            void *vto = page_address(pkt->pages[p]) + offs;
            memcpy(vto, vfrom, CD_FRAMESIZE);
            kunmap_atomic(vfrom);
            bvec[f].bv_page = pkt->pages[p];
            bvec[f].bv_offset = offs;
        } else {
            BUG_ON(bvec[f].bv_offset != offs);
        }
        offs += CD_FRAMESIZE;
        if (offs >= PAGE_SIZE) {
            offs = 0;
            p++;
        }
    }
}

static void pkt_end_io_read(struct bio *bio, int err)
{
    struct packet_data *pkt = bio->bi_private;
    struct pktcdvd_device *pd = pkt->pd;
    BUG_ON(!pd);

    VPRINTK("pkt_end_io_read: bio=%p sec0=%llx sec=%llx err=%d\n", bio,
        (unsigned long long)pkt->sector, (unsigned long long)bio->bi_sector, err);

    if (err)
        atomic_inc(&pkt->io_errors);
    if (atomic_dec_and_test(&pkt->io_wait)) {
        atomic_inc(&pkt->run_sm);
        wake_up(&pd->wqueue);
    }
    pkt_bio_finished(pd);
}

static void pkt_end_io_packet_write(struct bio *bio, int err)
{
    struct packet_data *pkt = bio->bi_private;
    struct pktcdvd_device *pd = pkt->pd;
    BUG_ON(!pd);

    VPRINTK("pkt_end_io_packet_write: id=%d, err=%d\n", pkt->id, err);

    pd->stats.pkt_ended++;

    pkt_bio_finished(pd);
    atomic_dec(&pkt->io_wait);
    atomic_inc(&pkt->run_sm);
    wake_up(&pd->wqueue);
}

/*
 * Schedule reads for the holes in a packet
 */
static void pkt_gather_data(struct pktcdvd_device *pd, struct packet_data *pkt)
{
    int frames_read = 0;
    struct bio *bio;
    int f;
    char written[PACKET_MAX_SIZE];

    BUG_ON(bio_list_empty(&pkt->orig_bios));

    atomic_set(&pkt->io_wait, 0);
    atomic_set(&pkt->io_errors, 0);

    /*
     * Figure out which frames we need to read before we can write.
     */
    memset(written, 0, sizeof(written));
    spin_lock(&pkt->lock);
    bio_list_for_each(bio, &pkt->orig_bios) {
        int first_frame = (bio->bi_sector - pkt->sector) / (CD_FRAMESIZE >> 9);
        int num_frames = bio->bi_size / CD_FRAMESIZE;
        pd->stats.secs_w += num_frames * (CD_FRAMESIZE >> 9);
        BUG_ON(first_frame < 0);
        BUG_ON(first_frame + num_frames > pkt->frames);
        for (f = first_frame; f < first_frame + num_frames; f++)
            written[f] = 1;
    }
    spin_unlock(&pkt->lock);

    if (pkt->cache_valid) {
        VPRINTK("pkt_gather_data: zone %llx cached\n",
            (unsigned long long)pkt->sector);
        goto out_account;
    }

    /*
     * Schedule reads for missing parts of the packet.
     */
    for (f = 0; f < pkt->frames; f++) {
        int p, offset;

        if (written[f])
            continue;

        bio = pkt->r_bios[f];
        bio_reset(bio);
        bio->bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
        bio->bi_bdev = pd->bdev;
        bio->bi_end_io = pkt_end_io_read;
        bio->bi_private = pkt;

        p = (f * CD_FRAMESIZE) / PAGE_SIZE;
        offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
        VPRINTK("pkt_gather_data: Adding frame %d, page:%p offs:%d\n",
            f, pkt->pages[p], offset);
        if (!bio_add_page(bio, pkt->pages[p], CD_FRAMESIZE, offset))
            BUG();

        atomic_inc(&pkt->io_wait);
        bio->bi_rw = READ;
        pkt_queue_bio(pd, bio);
        frames_read++;
    }

out_account:
    VPRINTK("pkt_gather_data: need %d frames for zone %llx\n",
        frames_read, (unsigned long long)pkt->sector);
    pd->stats.pkt_started++;
    pd->stats.secs_rg += frames_read * (CD_FRAMESIZE >> 9);
}

/*
 * Find a packet matching zone, or the least recently used packet if
 * there is no match.
 */
static struct packet_data *pkt_get_packet_data(struct pktcdvd_device *pd, int zone)
{
    struct packet_data *pkt;

    list_for_each_entry(pkt, &pd->cdrw.pkt_free_list, list) {
        if (pkt->sector == zone || pkt->list.next == &pd->cdrw.pkt_free_list) {
            list_del_init(&pkt->list);
            if (pkt->sector != zone)
                pkt->cache_valid = 0;
            return pkt;
        }
    }
    BUG();
    return NULL;
}

static void pkt_put_packet_data(struct pktcdvd_device *pd, struct packet_data *pkt)
{
    if (pkt->cache_valid) {
        list_add(&pkt->list, &pd->cdrw.pkt_free_list);
    } else {
        list_add_tail(&pkt->list, &pd->cdrw.pkt_free_list);
    }
}

/*
 * recover a failed write, query for relocation if possible
 *
 * returns 1 if recovery is possible, or 0 if not
 *
 */
static int pkt_start_recovery(struct packet_data *pkt)
{
    /*
     * FIXME. We need help from the file system to implement
     * recovery handling.
     */
    return 0;
#if 0
    struct request *rq = pkt->rq;
    struct pktcdvd_device *pd = rq->rq_disk->private_data;
    struct block_device *pkt_bdev;
    struct super_block *sb = NULL;
    unsigned long old_block, new_block;
    sector_t new_sector;

    pkt_bdev = bdget(kdev_t_to_nr(pd->pkt_dev));
    if (pkt_bdev) {
        sb = get_super(pkt_bdev);
        bdput(pkt_bdev);
    }

    if (!sb)
        return 0;

    if (!sb->s_op->relocate_blocks)
        goto out;

    old_block = pkt->sector / (CD_FRAMESIZE >> 9);
    if (sb->s_op->relocate_blocks(sb, old_block, &new_block))
        goto out;

    new_sector = new_block * (CD_FRAMESIZE >> 9);
    pkt->sector = new_sector;

    pkt->bio->bi_sector = new_sector;
    pkt->bio->bi_next = NULL;
    pkt->bio->bi_flags = 1 << BIO_UPTODATE;
    pkt->bio->bi_idx = 0;

    BUG_ON(pkt->bio->bi_rw != REQ_WRITE);
    BUG_ON(pkt->bio->bi_vcnt != pkt->frames);
    BUG_ON(pkt->bio->bi_size != pkt->frames * CD_FRAMESIZE);
    BUG_ON(pkt->bio->bi_end_io != pkt_end_io_packet_write);
    BUG_ON(pkt->bio->bi_private != pkt);

    drop_super(sb);
    return 1;

out:
    drop_super(sb);
    return 0;
#endif
}

static inline void pkt_set_state(struct packet_data *pkt, enum packet_data_state state)
{
#if PACKET_DEBUG > 1
    static const char *state_name[] = {
        "IDLE", "WAITING", "READ_WAIT", "WRITE_WAIT", "RECOVERY", "FINISHED"
    };
    enum packet_data_state old_state = pkt->state;
    VPRINTK("pkt %2d : s=%6llx %s -> %s\n", pkt->id, (unsigned long long)pkt->sector,
        state_name[old_state], state_name[state]);
#endif
    pkt->state = state;
}

/*
 * Scan the work queue to see if we can start a new packet.
 * returns non-zero if any work was done.
 */
static int pkt_handle_queue(struct pktcdvd_device *pd)
{
    struct packet_data *pkt, *p;
    struct bio *bio = NULL;
    sector_t zone = 0; /* Suppress gcc warning */
    struct pkt_rb_node *node, *first_node;
    struct rb_node *n;
    int wakeup;

    VPRINTK("handle_queue\n");

    atomic_set(&pd->scan_queue, 0);

    if (list_empty(&pd->cdrw.pkt_free_list)) {
        VPRINTK("handle_queue: no pkt\n");
        return 0;
    }

    /*
     * Try to find a zone we are not already working on.
     */
    spin_lock(&pd->lock);
    first_node = pkt_rbtree_find(pd, pd->current_sector);
    if (!first_node) {
        n = rb_first(&pd->bio_queue);
        if (n)
            first_node = rb_entry(n, struct pkt_rb_node, rb_node);
    }
    node = first_node;
    while (node) {
        bio = node->bio;
        zone = ZONE(bio->bi_sector, pd);
        list_for_each_entry(p, &pd->cdrw.pkt_active_list, list) {
            if (p->sector == zone) {
                bio = NULL;
                goto try_next_bio;
            }
        }
        break;
try_next_bio:
        node = pkt_rbtree_next(node);
        if (!node) {
            n = rb_first(&pd->bio_queue);
            if (n)
                node = rb_entry(n, struct pkt_rb_node, rb_node);
        }
        if (node == first_node)
            node = NULL;
    }
    spin_unlock(&pd->lock);
    if (!bio) {
        VPRINTK("handle_queue: no bio\n");
        return 0;
    }

    pkt = pkt_get_packet_data(pd, zone);

    pd->current_sector = zone + pd->settings.size;
    pkt->sector = zone;
    BUG_ON(pkt->frames != pd->settings.size >> 2);
    pkt->write_size = 0;

    /*
     * Scan work queue for bios in the same zone and link them
     * to this packet.
     */
    spin_lock(&pd->lock);
    VPRINTK("pkt_handle_queue: looking for zone %llx\n", (unsigned long long)zone);
    while ((node = pkt_rbtree_find(pd, zone)) != NULL) {
        bio = node->bio;
        VPRINTK("pkt_handle_queue: found zone=%llx\n",
            (unsigned long long)ZONE(bio->bi_sector, pd));
        if (ZONE(bio->bi_sector, pd) != zone)
            break;
        pkt_rbtree_erase(pd, node);
        spin_lock(&pkt->lock);
        bio_list_add(&pkt->orig_bios, bio);
        pkt->write_size += bio->bi_size / CD_FRAMESIZE;
        spin_unlock(&pkt->lock);
    }
    /* check write congestion marks, and if bio_queue_size is
       below, wake up any waiters */
    wakeup = (pd->write_congestion_on > 0
            && pd->bio_queue_size <= pd->write_congestion_off);
    spin_unlock(&pd->lock);
    if (wakeup) {
        clear_bdi_congested(&pd->disk->queue->backing_dev_info,
                    BLK_RW_ASYNC);
    }

    pkt->sleep_time = max(PACKET_WAIT_TIME, 1);
    pkt_set_state(pkt, PACKET_WAITING_STATE);
    atomic_set(&pkt->run_sm, 1);

    spin_lock(&pd->cdrw.active_list_lock);
    list_add(&pkt->list, &pd->cdrw.pkt_active_list);
    spin_unlock(&pd->cdrw.active_list_lock);

    return 1;
}

/*
 * Assemble a bio to write one packet and queue the bio for processing
 * by the underlying block device.
 */
static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
{
    struct bio *bio;
    int f;
    int frames_write;
    struct bio_vec *bvec = pkt->w_bio->bi_io_vec;

    for (f = 0; f < pkt->frames; f++) {
        bvec[f].bv_page = pkt->pages[(f * CD_FRAMESIZE) / PAGE_SIZE];
        bvec[f].bv_offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
    }

    /*
     * Fill-in bvec with data from orig_bios.
     */
    frames_write = 0;
    spin_lock(&pkt->lock);
    bio_list_for_each(bio, &pkt->orig_bios) {
        int segment = bio->bi_idx;
        int src_offs = 0;
        int first_frame = (bio->bi_sector - pkt->sector) / (CD_FRAMESIZE >> 9);
        int num_frames = bio->bi_size / CD_FRAMESIZE;
        BUG_ON(first_frame < 0);
        BUG_ON(first_frame + num_frames > pkt->frames);
        for (f = first_frame; f < first_frame + num_frames; f++) {
            struct bio_vec *src_bvl = bio_iovec_idx(bio, segment);

            while (src_offs >= src_bvl->bv_len) {
                src_offs -= src_bvl->bv_len;
                segment++;
                BUG_ON(segment >= bio->bi_vcnt);
                src_bvl = bio_iovec_idx(bio, segment);
            }

            if (src_bvl->bv_len - src_offs >= CD_FRAMESIZE) {
                bvec[f].bv_page = src_bvl->bv_page;
                bvec[f].bv_offset = src_bvl->bv_offset + src_offs;
            } else {
                pkt_copy_bio_data(bio, segment, src_offs,
                          bvec[f].bv_page, bvec[f].bv_offset);
            }
            src_offs += CD_FRAMESIZE;
            frames_write++;
        }
    }
    pkt_set_state(pkt, PACKET_WRITE_WAIT_STATE);
    spin_unlock(&pkt->lock);

    VPRINTK("pkt_start_write: Writing %d frames for zone %llx\n",
        frames_write, (unsigned long long)pkt->sector);
    BUG_ON(frames_write != pkt->write_size);

    if (test_bit(PACKET_MERGE_SEGS, &pd->flags) || (pkt->write_size < pkt->frames)) {
        pkt_make_local_copy(pkt, bvec);
        pkt->cache_valid = 1;
    } else {
        pkt->cache_valid = 0;
    }

    /* Start the write request */
    bio_reset(pkt->w_bio);
    pkt->w_bio->bi_sector = pkt->sector;
    pkt->w_bio->bi_bdev = pd->bdev;
    pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
    pkt->w_bio->bi_private = pkt;
    for (f = 0; f < pkt->frames; f++)
        if (!bio_add_page(pkt->w_bio, bvec[f].bv_page, CD_FRAMESIZE, bvec[f].bv_offset))
            BUG();
    VPRINTK(DRIVER_NAME": vcnt=%d\n", pkt->w_bio->bi_vcnt);

    atomic_set(&pkt->io_wait, 1);
    pkt->w_bio->bi_rw = WRITE;
    pkt_queue_bio(pd, pkt->w_bio);
}

static void pkt_finish_packet(struct packet_data *pkt, int uptodate)
{
    struct bio *bio;

    if (!uptodate)
        pkt->cache_valid = 0;

    /* Finish all bios corresponding to this packet */
    while ((bio = bio_list_pop(&pkt->orig_bios)))
        bio_endio(bio, uptodate ? 0 : -EIO);
}

static void pkt_run_state_machine(struct pktcdvd_device *pd, struct packet_data *pkt)
{
    int uptodate;

    VPRINTK("run_state_machine: pkt %d\n", pkt->id);

    for (;;) {
        switch (pkt->state) {
        case PACKET_WAITING_STATE:
            if ((pkt->write_size < pkt->frames) && (pkt->sleep_time > 0))
                return;

            pkt->sleep_time = 0;
            pkt_gather_data(pd, pkt);
            pkt_set_state(pkt, PACKET_READ_WAIT_STATE);
            break;

        case PACKET_READ_WAIT_STATE:
            if (atomic_read(&pkt->io_wait) > 0)
                return;

            if (atomic_read(&pkt->io_errors) > 0) {
                pkt_set_state(pkt, PACKET_RECOVERY_STATE);
            } else {
                pkt_start_write(pd, pkt);
            }
            break;

        case PACKET_WRITE_WAIT_STATE:
            if (atomic_read(&pkt->io_wait) > 0)
                return;

            if (test_bit(BIO_UPTODATE, &pkt->w_bio->bi_flags)) {
                pkt_set_state(pkt, PACKET_FINISHED_STATE);
            } else {
                pkt_set_state(pkt, PACKET_RECOVERY_STATE);
            }
            break;

        case PACKET_RECOVERY_STATE:
            if (pkt_start_recovery(pkt)) {
                pkt_start_write(pd, pkt);
            } else {
                VPRINTK("No recovery possible\n");
                pkt_set_state(pkt, PACKET_FINISHED_STATE);
            }
            break;

        case PACKET_FINISHED_STATE:
            uptodate = test_bit(BIO_UPTODATE, &pkt->w_bio->bi_flags);
            pkt_finish_packet(pkt, uptodate);
            return;

        default:
            BUG();
            break;
        }
    }
}

static void pkt_handle_packets(struct pktcdvd_device *pd)
{
    struct packet_data *pkt, *next;

    VPRINTK("pkt_handle_packets\n");

    /*
     * Run state machine for active packets
     */
    list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
        if (atomic_read(&pkt->run_sm) > 0) {
            atomic_set(&pkt->run_sm, 0);
            pkt_run_state_machine(pd, pkt);
        }
    }

    /*
     * Move no longer active packets to the free list
     */
    spin_lock(&pd->cdrw.active_list_lock);
    list_for_each_entry_safe(pkt, next, &pd->cdrw.pkt_active_list, list) {
        if (pkt->state == PACKET_FINISHED_STATE) {
            list_del(&pkt->list);
            pkt_put_packet_data(pd, pkt);
            pkt_set_state(pkt, PACKET_IDLE_STATE);
            atomic_set(&pd->scan_queue, 1);
        }
    }
    spin_unlock(&pd->cdrw.active_list_lock);
}

static void pkt_count_states(struct pktcdvd_device *pd, int *states)
{
    struct packet_data *pkt;
    int i;

    for (i = 0; i < PACKET_NUM_STATES; i++)
        states[i] = 0;

    spin_lock(&pd->cdrw.active_list_lock);
    list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
        states[pkt->state]++;
    }
    spin_unlock(&pd->cdrw.active_list_lock);
}

/*
 * kcdrwd is woken up when writes have been queued for one of our
 * registered devices
 */
static int kcdrwd(void *foobar)
{
    struct pktcdvd_device *pd = foobar;
    struct packet_data *pkt;
    long min_sleep_time, residue;

    set_user_nice(current, -20);
    set_freezable();

    for (;;) {
        DECLARE_WAITQUEUE(wait, current);

        /*
         * Wait until there is something to do
         */
        add_wait_queue(&pd->wqueue, &wait);
        for (;;) {
            set_current_state(TASK_INTERRUPTIBLE);

            /* Check if we need to run pkt_handle_queue */
            if (atomic_read(&pd->scan_queue) > 0)
                goto work_to_do;

            /* Check if we need to run the state machine for some packet */
            list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
                if (atomic_read(&pkt->run_sm) > 0)
                    goto work_to_do;
            }

            /* Check if we need to process the iosched queues */
            if (atomic_read(&pd->iosched.attention) != 0)
                goto work_to_do;

            /* Otherwise, go to sleep */
            if (PACKET_DEBUG > 1) {
                int states[PACKET_NUM_STATES];
                pkt_count_states(pd, states);
                VPRINTK("kcdrwd: i:%d ow:%d rw:%d ww:%d rec:%d fin:%d\n",
                    states[0], states[1], states[2], states[3],
                    states[4], states[5]);
            }

            min_sleep_time = MAX_SCHEDULE_TIMEOUT;
            list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
                if (pkt->sleep_time && pkt->sleep_time < min_sleep_time)
                    min_sleep_time = pkt->sleep_time;
            }

            VPRINTK("kcdrwd: sleeping\n");
            residue = schedule_timeout(min_sleep_time);
            VPRINTK("kcdrwd: wake up\n");

            /* make swsusp happy with our thread */
            try_to_freeze();

            list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
                if (!pkt->sleep_time)
                    continue;
                pkt->sleep_time -= min_sleep_time - residue;
                if (pkt->sleep_time <= 0) {
                    pkt->sleep_time = 0;
                    atomic_inc(&pkt->run_sm);
                }
            }

            if (kthread_should_stop())
                break;
        }
work_to_do:
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&pd->wqueue, &wait);

        if (kthread_should_stop())
            break;

        /*
         * if pkt_handle_queue returns true, we can queue
         * another request.
         */
        while (pkt_handle_queue(pd))
            ;

        /*
         * Handle packet state machine
         */
        pkt_handle_packets(pd);

        /*
         * Handle iosched queues
         */
        pkt_iosched_process_queue(pd);
    }

    return 0;
}

static void pkt_print_settings(struct pktcdvd_device *pd)
{
    printk(DRIVER_NAME": %s packets, ", pd->settings.fp ? "Fixed" : "Variable");
    printk("%u blocks, ", pd->settings.size >> 2);
    printk("Mode-%c disc\n", pd->settings.block_mode == 8 ? '1' : '2');
}

static int pkt_mode_sense(struct pktcdvd_device *pd, struct packet_command *cgc, int page_code, int page_control)
{
    memset(cgc->cmd, 0, sizeof(cgc->cmd));

    cgc->cmd[0] = GPCMD_MODE_SENSE_10;
    cgc->cmd[2] = page_code | (page_control << 6);
    cgc->cmd[7] = cgc->buflen >> 8;
    cgc->cmd[8] = cgc->buflen & 0xff;
    cgc->data_direction = CGC_DATA_READ;
    return pkt_generic_packet(pd, cgc);
}

static int pkt_mode_select(struct pktcdvd_device *pd, struct packet_command *cgc)
{
    memset(cgc->cmd, 0, sizeof(cgc->cmd));
    memset(cgc->buffer, 0, 2);
    cgc->cmd[0] = GPCMD_MODE_SELECT_10;
    cgc->cmd[1] = 0x10;     /* PF */
    cgc->cmd[7] = cgc->buflen >> 8;
    cgc->cmd[8] = cgc->buflen & 0xff;
    cgc->data_direction = CGC_DATA_WRITE;
    return pkt_generic_packet(pd, cgc);
}

static int pkt_get_disc_info(struct pktcdvd_device *pd, disc_information *di)
{
    struct packet_command cgc;
    int ret;

    /* set up command and get the disc info */
    init_cdrom_command(&cgc, di, sizeof(*di), CGC_DATA_READ);
    cgc.cmd[0] = GPCMD_READ_DISC_INFO;
    cgc.cmd[8] = cgc.buflen = 2;
    cgc.quiet = 1;

    if ((ret = pkt_generic_packet(pd, &cgc)))
        return ret;

    /* not all drives have the same disc_info length, so requeue
     * packet with the length the drive tells us it can supply
     */
    cgc.buflen = be16_to_cpu(di->disc_information_length) +
             sizeof(di->disc_information_length);

    if (cgc.buflen > sizeof(disc_information))
        cgc.buflen = sizeof(disc_information);

    cgc.cmd[8] = cgc.buflen;
    return pkt_generic_packet(pd, &cgc);
}

static int pkt_get_track_info(struct pktcdvd_device *pd, __u16 track, __u8 type, track_information *ti)
{
    struct packet_command cgc;
    int ret;

    init_cdrom_command(&cgc, ti, 8, CGC_DATA_READ);
    cgc.cmd[0] = GPCMD_READ_TRACK_RZONE_INFO;
    cgc.cmd[1] = type & 3;
    cgc.cmd[4] = (track & 0xff00) >> 8;
    cgc.cmd[5] = track & 0xff;
    cgc.cmd[8] = 8;
    cgc.quiet = 1;

    if ((ret = pkt_generic_packet(pd, &cgc)))
        return ret;

    cgc.buflen = be16_to_cpu(ti->track_information_length) +
             sizeof(ti->track_information_length);

    if (cgc.buflen > sizeof(track_information))
        cgc.buflen = sizeof(track_information);

    cgc.cmd[8] = cgc.buflen;
    return pkt_generic_packet(pd, &cgc);
}

static noinline_for_stack int pkt_get_last_written(struct pktcdvd_device *pd,
                        long *last_written)
{
    disc_information di;
    track_information ti;
    __u32 last_track;
    int ret = -1;

    if ((ret = pkt_get_disc_info(pd, &di)))
        return ret;

    last_track = (di.last_track_msb << 8) | di.last_track_lsb;
    if ((ret = pkt_get_track_info(pd, last_track, 1, &ti)))
        return ret;

    /* if this track is blank, try the previous. */
    if (ti.blank) {
        last_track--;
        if ((ret = pkt_get_track_info(pd, last_track, 1, &ti)))
            return ret;
    }

    /* if last recorded field is valid, return it. */
    if (ti.lra_v) {
        *last_written = be32_to_cpu(ti.last_rec_address);
    } else {
        /* make it up instead */
        *last_written = be32_to_cpu(ti.track_start) +
                be32_to_cpu(ti.track_size);
        if (ti.free_blocks)
            *last_written -= (be32_to_cpu(ti.free_blocks) + 7);
    }
    return 0;
}

/*
 * write mode select package based on pd->settings
 */
static noinline_for_stack int pkt_set_write_settings(struct pktcdvd_device *pd)
{
    struct packet_command cgc;
    struct request_sense sense;
    write_param_page *wp;
    char buffer[128];
    int ret, size;

    /* doesn't apply to DVD+RW or DVD-RAM */
    if ((pd->mmc3_profile == 0x1a) || (pd->mmc3_profile == 0x12))
        return 0;

    memset(buffer, 0, sizeof(buffer));
    init_cdrom_command(&cgc, buffer, sizeof(*wp), CGC_DATA_READ);
    cgc.sense = &sense;
    if ((ret = pkt_mode_sense(pd, &cgc, GPMODE_WRITE_PARMS_PAGE, 0))) {
        pkt_dump_sense(&cgc);
        return ret;
    }

    size = 2 + ((buffer[0] << 8) | (buffer[1] & 0xff));
    pd->mode_offset = (buffer[6] << 8) | (buffer[7] & 0xff);
    if (size > sizeof(buffer))
        size = sizeof(buffer);

    /*
     * now get it all
     */
    init_cdrom_command(&cgc, buffer, size, CGC_DATA_READ);
    cgc.sense = &sense;
    if ((ret = pkt_mode_sense(pd, &cgc, GPMODE_WRITE_PARMS_PAGE, 0))) {
        pkt_dump_sense(&cgc);
        return ret;
    }

    /*
     * write page is offset header + block descriptor length
     */
    wp = (write_param_page *) &buffer[sizeof(struct mode_page_header) + pd->mode_offset];

    wp->fp = pd->settings.fp;
    wp->track_mode = pd->settings.track_mode;
    wp->write_type = pd->settings.write_type;
    wp->data_block_type = pd->settings.block_mode;

    wp->multi_session = 0;

#ifdef PACKET_USE_LS
    wp->link_size = 7;
    wp->ls_v = 1;
#endif

    if (wp->data_block_type == PACKET_BLOCK_MODE1) {
        wp->session_format = 0;
        wp->subhdr2 = 0x20;
    } else if (wp->data_block_type == PACKET_BLOCK_MODE2) {
        wp->session_format = 0x20;
        wp->subhdr2 = 8;
#if 0
        wp->mcn[0] = 0x80;
        memcpy(&wp->mcn[1], PACKET_MCN, sizeof(wp->mcn) - 1);
#endif
    } else {
        /*
         * paranoia
         */
        printk(DRIVER_NAME": write mode wrong %d\n", wp->data_block_type);
        return 1;
    }
    wp->packet_size = cpu_to_be32(pd->settings.size >> 2);

    cgc.buflen = cgc.cmd[8] = size;
    if ((ret = pkt_mode_select(pd, &cgc))) {
        pkt_dump_sense(&cgc);
        return ret;
    }

    pkt_print_settings(pd);
    return 0;
}

/*
 * 1 -- we can write to this track, 0 -- we can't
 */
static int pkt_writable_track(struct pktcdvd_device *pd, track_information *ti)
{
    switch (pd->mmc3_profile) {
        case 0x1a: /* DVD+RW */
        case 0x12: /* DVD-RAM */
            /* The track is always writable on DVD+RW/DVD-RAM */
            return 1;
        default:
            break;
    }

    if (!ti->packet || !ti->fp)
        return 0;

    /*
     * "good" settings as per Mt Fuji.
     */
    if (ti->rt == 0 && ti->blank == 0)
        return 1;

    if (ti->rt == 0 && ti->blank == 1)
        return 1;

    if (ti->rt == 1 && ti->blank == 0)
        return 1;

    printk(DRIVER_NAME": bad state %d-%d-%d\n", ti->rt, ti->blank, ti->packet);
    return 0;
}

/*
 * 1 -- we can write to this disc, 0 -- we can't
 */
static int pkt_writable_disc(struct pktcdvd_device *pd, disc_information *di)
{
    switch (pd->mmc3_profile) {
        case 0x0a: /* CD-RW */
        case 0xffff: /* MMC3 not supported */
            break;
        case 0x1a: /* DVD+RW */
        case 0x13: /* DVD-RW */
        case 0x12: /* DVD-RAM */
            return 1;
        default:
            VPRINTK(DRIVER_NAME": Wrong disc profile (%x)\n", pd->mmc3_profile);
            return 0;
    }

    /*
     * for disc type 0xff we should probably reserve a new track.
     * but i'm not sure, should we leave this to user apps? probably.
     */
    if (di->disc_type == 0xff) {
        printk(DRIVER_NAME": Unknown disc. No track?\n");
        return 0;
    }

    if (di->disc_type != 0x20 && di->disc_type != 0) {
        printk(DRIVER_NAME": Wrong disc type (%x)\n", di->disc_type);
        return 0;
    }

    if (di->erasable == 0) {
        printk(DRIVER_NAME": Disc not erasable\n");
        return 0;
    }

    if (di->border_status == PACKET_SESSION_RESERVED) {
        printk(DRIVER_NAME": Can't write to last track (reserved)\n");
        return 0;
    }

    return 1;
}

static noinline_for_stack int pkt_probe_settings(struct pktcdvd_device *pd)
{
    struct packet_command cgc;
    unsigned char buf[12];
    disc_information di;
    track_information ti;
    int ret, track;

    init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
    cgc.cmd[0] = GPCMD_GET_CONFIGURATION;
    cgc.cmd[8] = 8;
    ret = pkt_generic_packet(pd, &cgc);
    pd->mmc3_profile = ret ? 0xffff : buf[6] << 8 | buf[7];

    memset(&di, 0, sizeof(disc_information));
    memset(&ti, 0, sizeof(track_information));

    if ((ret = pkt_get_disc_info(pd, &di))) {
        printk("failed get_disc\n");
        return ret;
    }

    if (!pkt_writable_disc(pd, &di))
        return -EROFS;

    pd->type = di.erasable ? PACKET_CDRW : PACKET_CDR;

    track = 1; /* (di.last_track_msb << 8) | di.last_track_lsb; */
    if ((ret = pkt_get_track_info(pd, track, 1, &ti))) {
        printk(DRIVER_NAME": failed get_track\n");
        return ret;
    }

    if (!pkt_writable_track(pd, &ti)) {
        printk(DRIVER_NAME": can't write to this track\n");
        return -EROFS;
    }

    /*
     * we keep packet size in 512 byte units, makes it easier to
     * deal with request calculations.
     */
    pd->settings.size = be32_to_cpu(ti.fixed_packet_size) << 2;
    if (pd->settings.size == 0) {
        printk(DRIVER_NAME": detected zero packet size!\n");
        return -ENXIO;
    }
    if (pd->settings.size > PACKET_MAX_SECTORS) {
        printk(DRIVER_NAME": packet size is too big\n");
        return -EROFS;
    }
    pd->settings.fp = ti.fp;
    pd->offset = (be32_to_cpu(ti.track_start) << 2) & (pd->settings.size - 1);

    if (ti.nwa_v) {
        pd->nwa = be32_to_cpu(ti.next_writable);
        set_bit(PACKET_NWA_VALID, &pd->flags);
    }

    /*
     * in theory we could use lra on -RW media as well and just zero
     * blocks that haven't been written yet, but in practice that
     * is just a no-go. we'll use that for -R, naturally.
     */
    if (ti.lra_v) {
        pd->lra = be32_to_cpu(ti.last_rec_address);
        set_bit(PACKET_LRA_VALID, &pd->flags);
    } else {
        pd->lra = 0xffffffff;
        set_bit(PACKET_LRA_VALID, &pd->flags);
    }

    /*
     * fine for now
     */
    pd->settings.link_loss = 7;
    pd->settings.write_type = 0;    /* packet */
    pd->settings.track_mode = ti.track_mode;

    /*
     * mode1 or mode2 disc
     */
    switch (ti.data_mode) {
        case PACKET_MODE1:
            pd->settings.block_mode = PACKET_BLOCK_MODE1;
            break;
        case PACKET_MODE2:
            pd->settings.block_mode = PACKET_BLOCK_MODE2;
            break;
        default:
            printk(DRIVER_NAME": unknown data mode\n");
            return -EROFS;
    }
    return 0;
}

/*
 * enable/disable write caching on drive
 */
static noinline_for_stack int pkt_write_caching(struct pktcdvd_device *pd,
                        int set)
{
    struct packet_command cgc;
    struct request_sense sense;
    unsigned char buf[64];
    int ret;

    init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
    cgc.sense = &sense;
    cgc.buflen = pd->mode_offset + 12;

    /*
     * caching mode page might not be there, so quiet this command
     */
    cgc.quiet = 1;

    if ((ret = pkt_mode_sense(pd, &cgc, GPMODE_WCACHING_PAGE, 0)))
        return ret;

    buf[pd->mode_offset + 10] |= (!!set << 2);

    cgc.buflen = cgc.cmd[8] = 2 + ((buf[0] << 8) | (buf[1] & 0xff));
    ret = pkt_mode_select(pd, &cgc);
    if (ret) {
        printk(DRIVER_NAME": write caching control failed\n");
        pkt_dump_sense(&cgc);
    } else if (!ret && set)
        printk(DRIVER_NAME": enabled write caching on %s\n", pd->name);
    return ret;
}

static int pkt_lock_door(struct pktcdvd_device *pd, int lockflag)
{
    struct packet_command cgc;

    init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
    cgc.cmd[0] = GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL;
    cgc.cmd[4] = lockflag ? 1 : 0;
    return pkt_generic_packet(pd, &cgc);
}

/*
 * Returns drive maximum write speed
 */
static noinline_for_stack int pkt_get_max_speed(struct pktcdvd_device *pd,
                        unsigned *write_speed)
{
    struct packet_command cgc;
    struct request_sense sense;
    unsigned char buf[256+18];
    unsigned char *cap_buf;
    int ret, offset;

    cap_buf = &buf[sizeof(struct mode_page_header) + pd->mode_offset];
    init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_UNKNOWN);
    cgc.sense = &sense;

    ret = pkt_mode_sense(pd, &cgc, GPMODE_CAPABILITIES_PAGE, 0);
    if (ret) {
        cgc.buflen = pd->mode_offset + cap_buf[1] + 2 +
                 sizeof(struct mode_page_header);
        ret = pkt_mode_sense(pd, &cgc, GPMODE_CAPABILITIES_PAGE, 0);
        if (ret) {
            pkt_dump_sense(&cgc);
            return ret;
        }
    }

    offset = 20;                /* Obsoleted field, used by older drives */
    if (cap_buf[1] >= 28)
        offset = 28;            /* Current write speed selected */
    if (cap_buf[1] >= 30) {
        /* If the drive reports at least one "Logical Unit Write
         * Speed Performance Descriptor Block", use the information
         * in the first block. (contains the highest speed)
         */
        int num_spdb = (cap_buf[30] << 8) + cap_buf[31];
        if (num_spdb > 0)
            offset = 34;
    }

    *write_speed = (cap_buf[offset] << 8) | cap_buf[offset + 1];
    return 0;
}

/* These tables from cdrecord - I don't have orange book */
/* standard speed CD-RW (1-4x) */
static char clv_to_speed[16] = {
    /* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
       0, 2, 4, 6, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
/* high speed CD-RW (-10x) */
static char hs_clv_to_speed[16] = {
    /* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
       0, 2, 4, 6, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
/* ultra high speed CD-RW */
static char us_clv_to_speed[16] = {
    /* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
       0, 2, 4, 8, 0, 0,16, 0,24,32,40,48, 0, 0, 0, 0
};

/*
 * reads the maximum media speed from ATIP
 */
static noinline_for_stack int pkt_media_speed(struct pktcdvd_device *pd,
                        unsigned *speed)
{
    struct packet_command cgc;
    struct request_sense sense;
    unsigned char buf[64];
    unsigned int size, st, sp;
    int ret;

    init_cdrom_command(&cgc, buf, 2, CGC_DATA_READ);
    cgc.sense = &sense;
    cgc.cmd[0] = GPCMD_READ_TOC_PMA_ATIP;
    cgc.cmd[1] = 2;
    cgc.cmd[2] = 4; /* READ ATIP */
    cgc.cmd[8] = 2;
    ret = pkt_generic_packet(pd, &cgc);
    if (ret) {
        pkt_dump_sense(&cgc);
        return ret;
    }
    size = ((unsigned int) buf[0]<<8) + buf[1] + 2;
    if (size > sizeof(buf))
        size = sizeof(buf);

    init_cdrom_command(&cgc, buf, size, CGC_DATA_READ);
    cgc.sense = &sense;
    cgc.cmd[0] = GPCMD_READ_TOC_PMA_ATIP;
    cgc.cmd[1] = 2;
    cgc.cmd[2] = 4;
    cgc.cmd[8] = size;
    ret = pkt_generic_packet(pd, &cgc);
    if (ret) {
        pkt_dump_sense(&cgc);
        return ret;
    }

    if (!(buf[6] & 0x40)) {
        printk(DRIVER_NAME": Disc type is not CD-RW\n");
        return 1;
    }
    if (!(buf[6] & 0x4)) {
        printk(DRIVER_NAME": A1 values on media are not valid, maybe not CDRW?\n");
        return 1;
    }

    st = (buf[6] >> 3) & 0x7; /* disc sub-type */

    sp = buf[16] & 0xf; /* max speed from ATIP A1 field */

    /* Info from cdrecord */
    switch (st) {
        case 0: /* standard speed */
            *speed = clv_to_speed[sp];
            break;
        case 1: /* high speed */
            *speed = hs_clv_to_speed[sp];
            break;
        case 2: /* ultra high speed */
            *speed = us_clv_to_speed[sp];
            break;
        default:
            printk(DRIVER_NAME": Unknown disc sub-type %d\n",st);
            return 1;
    }
    if (*speed) {
        printk(DRIVER_NAME": Max. media speed: %d\n",*speed);
        return 0;
    } else {
        printk(DRIVER_NAME": Unknown speed %d for sub-type %d\n",sp,st);
        return 1;
    }
}

static noinline_for_stack int pkt_perform_opc(struct pktcdvd_device *pd)
{
    struct packet_command cgc;
    struct request_sense sense;
    int ret;

    VPRINTK(DRIVER_NAME": Performing OPC\n");

    init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
    cgc.sense = &sense;
    cgc.timeout = 60*HZ;
    cgc.cmd[0] = GPCMD_SEND_OPC;
    cgc.cmd[1] = 1;
    if ((ret = pkt_generic_packet(pd, &cgc)))
        pkt_dump_sense(&cgc);
    return ret;
}

static int pkt_open_write(struct pktcdvd_device *pd)
{
    int ret;
    unsigned int write_speed, media_write_speed, read_speed;

    if ((ret = pkt_probe_settings(pd))) {
        VPRINTK(DRIVER_NAME": %s failed probe\n", pd->name);
        return ret;
    }

    if ((ret = pkt_set_write_settings(pd))) {
        DPRINTK(DRIVER_NAME": %s failed saving write settings\n", pd->name);
        return -EIO;
    }

    pkt_write_caching(pd, USE_WCACHING);

    if ((ret = pkt_get_max_speed(pd, &write_speed)))
        write_speed = 16 * 177;
    switch (pd->mmc3_profile) {
        case 0x13: /* DVD-RW */
        case 0x1a: /* DVD+RW */
        case 0x12: /* DVD-RAM */
            DPRINTK(DRIVER_NAME": write speed %ukB/s\n", write_speed);
            break;
        default:
            if ((ret = pkt_media_speed(pd, &media_write_speed)))
                media_write_speed = 16;
            write_speed = min(write_speed, media_write_speed * 177);
            DPRINTK(DRIVER_NAME": write speed %ux\n", write_speed / 176);
            break;
    }
    read_speed = write_speed;

    if ((ret = pkt_set_speed(pd, write_speed, read_speed))) {
        DPRINTK(DRIVER_NAME": %s couldn't set write speed\n", pd->name);
        return -EIO;
    }
    pd->write_speed = write_speed;
    pd->read_speed = read_speed;

    if ((ret = pkt_perform_opc(pd))) {
        DPRINTK(DRIVER_NAME": %s Optimum Power Calibration failed\n", pd->name);
    }

    return 0;
}

/*
 * called at open time.
 */
static int pkt_open_dev(struct pktcdvd_device *pd, fmode_t write)
{
    int ret;
    long lba;
    struct request_queue *q;

    /*
     * We need to re-open the cdrom device without O_NONBLOCK to be able
     * to read/write from/to it. It is already opened in O_NONBLOCK mode
     * so bdget() can't fail.
     */
    bdget(pd->bdev->bd_dev);
    if ((ret = blkdev_get(pd->bdev, FMODE_READ | FMODE_EXCL, pd)))
        goto out;

    if ((ret = pkt_get_last_written(pd, &lba))) {
        printk(DRIVER_NAME": pkt_get_last_written failed\n");
        goto out_putdev;
    }

    set_capacity(pd->disk, lba << 2);
    set_capacity(pd->bdev->bd_disk, lba << 2);
    bd_set_size(pd->bdev, (loff_t)lba << 11);

    q = bdev_get_queue(pd->bdev);
    if (write) {
        if ((ret = pkt_open_write(pd)))
            goto out_putdev;
        /*
         * Some CDRW drives can not handle writes larger than one packet,
         * even if the size is a multiple of the packet size.
         */
        spin_lock_irq(q->queue_lock);
        blk_queue_max_hw_sectors(q, pd->settings.size);
        spin_unlock_irq(q->queue_lock);
        set_bit(PACKET_WRITABLE, &pd->flags);
    } else {
        pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
        clear_bit(PACKET_WRITABLE, &pd->flags);
    }

    if ((ret = pkt_set_segment_merging(pd, q)))
        goto out_putdev;

    if (write) {
        if (!pkt_grow_pktlist(pd, CONFIG_CDROM_PKTCDVD_BUFFERS)) {
            printk(DRIVER_NAME": not enough memory for buffers\n");
            ret = -ENOMEM;
            goto out_putdev;
        }
        printk(DRIVER_NAME": %lukB available on disc\n", lba << 1);
    }

    return 0;

out_putdev:
    blkdev_put(pd->bdev, FMODE_READ | FMODE_EXCL);
out:
    return ret;
}

/*
 * called when the device is closed. makes sure that the device flushes
 * the internal cache before we close.
 */
static void pkt_release_dev(struct pktcdvd_device *pd, int flush)
{
    if (flush && pkt_flush_cache(pd))
        DPRINTK(DRIVER_NAME": %s not flushing cache\n", pd->name);

    pkt_lock_door(pd, 0);

    pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
    blkdev_put(pd->bdev, FMODE_READ | FMODE_EXCL);

    pkt_shrink_pktlist(pd);
}

static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor)
{
    if (dev_minor >= MAX_WRITERS)
        return NULL;
    return pkt_devs[dev_minor];
}

static int pkt_open(struct block_device *bdev, fmode_t mode)
{
    struct pktcdvd_device *pd = NULL;
    int ret;

    VPRINTK(DRIVER_NAME": entering open\n");

    mutex_lock(&pktcdvd_mutex);
    mutex_lock(&ctl_mutex);
    pd = pkt_find_dev_from_minor(MINOR(bdev->bd_dev));
    if (!pd) {
        ret = -ENODEV;
        goto out;
    }
    BUG_ON(pd->refcnt < 0);

    pd->refcnt++;
    if (pd->refcnt > 1) {
        if ((mode & FMODE_WRITE) &&
            !test_bit(PACKET_WRITABLE, &pd->flags)) {
            ret = -EBUSY;
            goto out_dec;
        }
    } else {
        ret = pkt_open_dev(pd, mode & FMODE_WRITE);
        if (ret)
            goto out_dec;
        /*
         * needed here as well, since ext2 (among others) may change
         * the blocksize at mount time
         */
        set_blocksize(bdev, CD_FRAMESIZE);
    }

    mutex_unlock(&ctl_mutex);
    mutex_unlock(&pktcdvd_mutex);
    return 0;

out_dec:
    pd->refcnt--;
out:
    VPRINTK(DRIVER_NAME": failed open (%d)\n", ret);
    mutex_unlock(&ctl_mutex);
    mutex_unlock(&pktcdvd_mutex);
    return ret;
}

static int pkt_close(struct gendisk *disk, fmode_t mode)
{
    struct pktcdvd_device *pd = disk->private_data;
    int ret = 0;

    mutex_lock(&pktcdvd_mutex);
    mutex_lock(&ctl_mutex);
    pd->refcnt--;
    BUG_ON(pd->refcnt < 0);
    if (pd->refcnt == 0) {
        int flush = test_bit(PACKET_WRITABLE, &pd->flags);
        pkt_release_dev(pd, flush);
    }
    mutex_unlock(&ctl_mutex);
    mutex_unlock(&pktcdvd_mutex);
    return ret;
}


static void pkt_end_io_read_cloned(struct bio *bio, int err)
{
    struct packet_stacked_data *psd = bio->bi_private;
    struct pktcdvd_device *pd = psd->pd;

    bio_put(bio);
    bio_endio(psd->bio, err);
    mempool_free(psd, psd_pool);
    pkt_bio_finished(pd);
}

static void pkt_make_request(struct request_queue *q, struct bio *bio)
{
    struct pktcdvd_device *pd;
    char b[BDEVNAME_SIZE];
    sector_t zone;
    struct packet_data *pkt;
    int was_empty, blocked_bio;
    struct pkt_rb_node *node;

    pd = q->queuedata;
    if (!pd) {
        printk(DRIVER_NAME": %s incorrect request queue\n", bdevname(bio->bi_bdev, b));
        goto end_io;
    }

    /*
     * Clone READ bios so we can have our own bi_end_io callback.
     */
    if (bio_data_dir(bio) == READ) {
        struct bio *cloned_bio = bio_clone(bio, GFP_NOIO);
        struct packet_stacked_data *psd = mempool_alloc(psd_pool, GFP_NOIO);

        psd->pd = pd;
        psd->bio = bio;
        cloned_bio->bi_bdev = pd->bdev;
        cloned_bio->bi_private = psd;
        cloned_bio->bi_end_io = pkt_end_io_read_cloned;
        pd->stats.secs_r += bio->bi_size >> 9;
        pkt_queue_bio(pd, cloned_bio);
        return;
    }

    if (!test_bit(PACKET_WRITABLE, &pd->flags)) {
        printk(DRIVER_NAME": WRITE for ro device %s (%llu)\n",
            pd->name, (unsigned long long)bio->bi_sector);
        goto end_io;
    }

    if (!bio->bi_size || (bio->bi_size % CD_FRAMESIZE)) {
        printk(DRIVER_NAME": wrong bio size\n");
        goto end_io;
    }

    blk_queue_bounce(q, &bio);

    zone = ZONE(bio->bi_sector, pd);
    VPRINTK("pkt_make_request: start = %6llx stop = %6llx\n",
        (unsigned long long)bio->bi_sector,
        (unsigned long long)(bio->bi_sector + bio_sectors(bio)));

    /* Check if we have to split the bio */
    {
        struct bio_pair *bp;
        sector_t last_zone;
        int first_sectors;

        last_zone = ZONE(bio->bi_sector + bio_sectors(bio) - 1, pd);
        if (last_zone != zone) {
            BUG_ON(last_zone != zone + pd->settings.size);
            first_sectors = last_zone - bio->bi_sector;
            bp = bio_split(bio, first_sectors);
            BUG_ON(!bp);
            pkt_make_request(q, &bp->bio1);
            pkt_make_request(q, &bp->bio2);
            bio_pair_release(bp);
            return;
        }
    }

    /*
     * If we find a matching packet in state WAITING or READ_WAIT, we can
     * just append this bio to that packet.
     */
    spin_lock(&pd->cdrw.active_list_lock);
    blocked_bio = 0;
    list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
        if (pkt->sector == zone) {
            spin_lock(&pkt->lock);
            if ((pkt->state == PACKET_WAITING_STATE) ||
                (pkt->state == PACKET_READ_WAIT_STATE)) {
                bio_list_add(&pkt->orig_bios, bio);
                pkt->write_size += bio->bi_size / CD_FRAMESIZE;
                if ((pkt->write_size >= pkt->frames) &&
                    (pkt->state == PACKET_WAITING_STATE)) {
                    atomic_inc(&pkt->run_sm);
                    wake_up(&pd->wqueue);
                }
                spin_unlock(&pkt->lock);
                spin_unlock(&pd->cdrw.active_list_lock);
                return;
            } else {
                blocked_bio = 1;
            }
            spin_unlock(&pkt->lock);
        }
    }
    spin_unlock(&pd->cdrw.active_list_lock);

    /*
     * Test if there is enough room left in the bio work queue
     * (queue size >= congestion on mark).
     * If not, wait till the work queue size is below the congestion off mark.
     */
    spin_lock(&pd->lock);
    if (pd->write_congestion_on > 0
        && pd->bio_queue_size >= pd->write_congestion_on) {
        set_bdi_congested(&q->backing_dev_info, BLK_RW_ASYNC);
        do {
            spin_unlock(&pd->lock);
            congestion_wait(BLK_RW_ASYNC, HZ);
            spin_lock(&pd->lock);
        } while(pd->bio_queue_size > pd->write_congestion_off);
    }
    spin_unlock(&pd->lock);

    /*
     * No matching packet found. Store the bio in the work queue.
     */
    node = mempool_alloc(pd->rb_pool, GFP_NOIO);
    node->bio = bio;
    spin_lock(&pd->lock);
    BUG_ON(pd->bio_queue_size < 0);
    was_empty = (pd->bio_queue_size == 0);
    pkt_rbtree_insert(pd, node);
    spin_unlock(&pd->lock);

    /*
     * Wake up the worker thread.
     */
    atomic_set(&pd->scan_queue, 1);
    if (was_empty) {
        /* This wake_up is required for correct operation */
        wake_up(&pd->wqueue);
    } else if (!list_empty(&pd->cdrw.pkt_free_list) && !blocked_bio) {
        /*
         * This wake up is not required for correct operation,
         * but improves performance in some cases.
         */
        wake_up(&pd->wqueue);
    }
    return;
end_io:
    bio_io_error(bio);
}



static int pkt_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
              struct bio_vec *bvec)
{
    struct pktcdvd_device *pd = q->queuedata;
    sector_t zone = ZONE(bmd->bi_sector, pd);
    int used = ((bmd->bi_sector - zone) << 9) + bmd->bi_size;
    int remaining = (pd->settings.size << 9) - used;
    int remaining2;

    /*
     * A bio <= PAGE_SIZE must be allowed. If it crosses a packet
     * boundary, pkt_make_request() will split the bio.
     */
    remaining2 = PAGE_SIZE - bmd->bi_size;
    remaining = max(remaining, remaining2);

    BUG_ON(remaining < 0);
    return remaining;
}

static void pkt_init_queue(struct pktcdvd_device *pd)
{
    struct request_queue *q = pd->disk->queue;

    blk_queue_make_request(q, pkt_make_request);
    blk_queue_logical_block_size(q, CD_FRAMESIZE);
    blk_queue_max_hw_sectors(q, PACKET_MAX_SECTORS);
    blk_queue_merge_bvec(q, pkt_merge_bvec);
    q->queuedata = pd;
}

static int pkt_seq_show(struct seq_file *m, void *p)
{
    struct pktcdvd_device *pd = m->private;
    char *msg;
    char bdev_buf[BDEVNAME_SIZE];
    int states[PACKET_NUM_STATES];

    seq_printf(m, "Writer %s mapped to %s:\n", pd->name,
           bdevname(pd->bdev, bdev_buf));

    seq_printf(m, "\nSettings:\n");
    seq_printf(m, "\tpacket size:\t\t%dkB\n", pd->settings.size / 2);

    if (pd->settings.write_type == 0)
        msg = "Packet";
    else
        msg = "Unknown";
    seq_printf(m, "\twrite type:\t\t%s\n", msg);

    seq_printf(m, "\tpacket type:\t\t%s\n", pd->settings.fp ? "Fixed" : "Variable");
    seq_printf(m, "\tlink loss:\t\t%d\n", pd->settings.link_loss);

    seq_printf(m, "\ttrack mode:\t\t%d\n", pd->settings.track_mode);

    if (pd->settings.block_mode == PACKET_BLOCK_MODE1)
        msg = "Mode 1";
    else if (pd->settings.block_mode == PACKET_BLOCK_MODE2)
        msg = "Mode 2";
    else
        msg = "Unknown";
    seq_printf(m, "\tblock mode:\t\t%s\n", msg);

    seq_printf(m, "\nStatistics:\n");
    seq_printf(m, "\tpackets started:\t%lu\n", pd->stats.pkt_started);
    seq_printf(m, "\tpackets ended:\t\t%lu\n", pd->stats.pkt_ended);
    seq_printf(m, "\twritten:\t\t%lukB\n", pd->stats.secs_w >> 1);
    seq_printf(m, "\tread gather:\t\t%lukB\n", pd->stats.secs_rg >> 1);
    seq_printf(m, "\tread:\t\t\t%lukB\n", pd->stats.secs_r >> 1);

    seq_printf(m, "\nMisc:\n");
    seq_printf(m, "\treference count:\t%d\n", pd->refcnt);
    seq_printf(m, "\tflags:\t\t\t0x%lx\n", pd->flags);
    seq_printf(m, "\tread speed:\t\t%ukB/s\n", pd->read_speed);
    seq_printf(m, "\twrite speed:\t\t%ukB/s\n", pd->write_speed);
    seq_printf(m, "\tstart offset:\t\t%lu\n", pd->offset);
    seq_printf(m, "\tmode page offset:\t%u\n", pd->mode_offset);

    seq_printf(m, "\nQueue state:\n");
    seq_printf(m, "\tbios queued:\t\t%d\n", pd->bio_queue_size);
    seq_printf(m, "\tbios pending:\t\t%d\n", atomic_read(&pd->cdrw.pending_bios));
    seq_printf(m, "\tcurrent sector:\t\t0x%llx\n", (unsigned long long)pd->current_sector);

    pkt_count_states(pd, states);
    seq_printf(m, "\tstate:\t\t\ti:%d ow:%d rw:%d ww:%d rec:%d fin:%d\n",
           states[0], states[1], states[2], states[3], states[4], states[5]);

    seq_printf(m, "\twrite congestion marks:\toff=%d on=%d\n",
            pd->write_congestion_off,
            pd->write_congestion_on);
    return 0;
}

static int pkt_seq_open(struct inode *inode, struct file *file)
{
    return single_open(file, pkt_seq_show, PDE(inode)->data);
}

static const struct file_operations pkt_proc_fops = {
    .open   = pkt_seq_open,
    .read   = seq_read,
    .llseek = seq_lseek,
    .release = single_release
};

static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
{
    int i;
    int ret = 0;
    char b[BDEVNAME_SIZE];
    struct block_device *bdev;

    if (pd->pkt_dev == dev) {
        printk(DRIVER_NAME": Recursive setup not allowed\n");
        return -EBUSY;
    }
    for (i = 0; i < MAX_WRITERS; i++) {
        struct pktcdvd_device *pd2 = pkt_devs[i];
        if (!pd2)
            continue;
        if (pd2->bdev->bd_dev == dev) {
            printk(DRIVER_NAME": %s already setup\n", bdevname(pd2->bdev, b));
            return -EBUSY;
        }
        if (pd2->pkt_dev == dev) {
            printk(DRIVER_NAME": Can't chain pktcdvd devices\n");
            return -EBUSY;
        }
    }

    bdev = bdget(dev);
    if (!bdev)
        return -ENOMEM;
    ret = blkdev_get(bdev, FMODE_READ | FMODE_NDELAY, NULL);
    if (ret)
        return ret;

    /* This is safe, since we have a reference from open(). */
    __module_get(THIS_MODULE);

    pd->bdev = bdev;
    set_blocksize(bdev, CD_FRAMESIZE);

    pkt_init_queue(pd);

    atomic_set(&pd->cdrw.pending_bios, 0);
    pd->cdrw.thread = kthread_run(kcdrwd, pd, "%s", pd->name);
    if (IS_ERR(pd->cdrw.thread)) {
        printk(DRIVER_NAME": can't start kernel thread\n");
        ret = -ENOMEM;
        goto out_mem;
    }

    proc_create_data(pd->name, 0, pkt_proc, &pkt_proc_fops, pd);
    DPRINTK(DRIVER_NAME": writer %s mapped to %s\n", pd->name, bdevname(bdev, b));
    return 0;

out_mem:
    blkdev_put(bdev, FMODE_READ | FMODE_NDELAY);
    /* This is safe: open() is still holding a reference. */
    module_put(THIS_MODULE);
    return ret;
}

static int pkt_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
{
    struct pktcdvd_device *pd = bdev->bd_disk->private_data;
    int ret;

    VPRINTK("pkt_ioctl: cmd %x, dev %d:%d\n", cmd,
        MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev));

    mutex_lock(&pktcdvd_mutex);
    switch (cmd) {
    case CDROMEJECT:
        /*
         * The door gets locked when the device is opened, so we
         * have to unlock it or else the eject command fails.
         */
        if (pd->refcnt == 1)
            pkt_lock_door(pd, 0);
        /* fallthru */
    /*
     * forward selected CDROM ioctls to CD-ROM, for UDF
     */
    case CDROMMULTISESSION:
    case CDROMREADTOCENTRY:
    case CDROM_LAST_WRITTEN:
    case CDROM_SEND_PACKET:
    case SCSI_IOCTL_SEND_COMMAND:
        ret = __blkdev_driver_ioctl(pd->bdev, mode, cmd, arg);
        break;

    default:
        VPRINTK(DRIVER_NAME": Unknown ioctl for %s (%x)\n", pd->name, cmd);
        ret = -ENOTTY;
    }
    mutex_unlock(&pktcdvd_mutex);

    return ret;
}

static unsigned int pkt_check_events(struct gendisk *disk,
                     unsigned int clearing)
{
    struct pktcdvd_device *pd = disk->private_data;
    struct gendisk *attached_disk;

    if (!pd)
        return 0;
    if (!pd->bdev)
        return 0;
    attached_disk = pd->bdev->bd_disk;
    if (!attached_disk || !attached_disk->fops->check_events)
        return 0;
    return attached_disk->fops->check_events(attached_disk, clearing);
}

static const struct block_device_operations pktcdvd_ops = {
    .owner =        THIS_MODULE,
    .open =         pkt_open,
    .release =      pkt_close,
    .ioctl =        pkt_ioctl,
    .check_events =     pkt_check_events,
};

static char *pktcdvd_devnode(struct gendisk *gd, umode_t *mode)
{
    return kasprintf(GFP_KERNEL, "pktcdvd/%s", gd->disk_name);
}

/*
 * Set up mapping from pktcdvd device to CD-ROM device.
 */
static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
{
    int idx;
    int ret = -ENOMEM;
    struct pktcdvd_device *pd;
    struct gendisk *disk;

    mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);

    for (idx = 0; idx < MAX_WRITERS; idx++)
        if (!pkt_devs[idx])
            break;
    if (idx == MAX_WRITERS) {
        printk(DRIVER_NAME": max %d writers supported\n", MAX_WRITERS);
        ret = -EBUSY;
        goto out_mutex;
    }

    pd = kzalloc(sizeof(struct pktcdvd_device), GFP_KERNEL);
    if (!pd)
        goto out_mutex;

    pd->rb_pool = mempool_create_kmalloc_pool(PKT_RB_POOL_SIZE,
                          sizeof(struct pkt_rb_node));
    if (!pd->rb_pool)
        goto out_mem;

    INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
    INIT_LIST_HEAD(&pd->cdrw.pkt_active_list);
    spin_lock_init(&pd->cdrw.active_list_lock);

    spin_lock_init(&pd->lock);
    spin_lock_init(&pd->iosched.lock);
    bio_list_init(&pd->iosched.read_queue);
    bio_list_init(&pd->iosched.write_queue);
    sprintf(pd->name, DRIVER_NAME"%d", idx);
    init_waitqueue_head(&pd->wqueue);
    pd->bio_queue = RB_ROOT;

    pd->write_congestion_on  = write_congestion_on;
    pd->write_congestion_off = write_congestion_off;

    disk = alloc_disk(1);
    if (!disk)
        goto out_mem;
    pd->disk = disk;
    disk->major = pktdev_major;
    disk->first_minor = idx;
    disk->fops = &pktcdvd_ops;
    disk->flags = GENHD_FL_REMOVABLE;
    strcpy(disk->disk_name, pd->name);
    disk->devnode = pktcdvd_devnode;
    disk->private_data = pd;
    disk->queue = blk_alloc_queue(GFP_KERNEL);
    if (!disk->queue)
        goto out_mem2;

    pd->pkt_dev = MKDEV(pktdev_major, idx);
    ret = pkt_new_dev(pd, dev);
    if (ret)
        goto out_new_dev;

    /* inherit events of the host device */
    disk->events = pd->bdev->bd_disk->events;
    disk->async_events = pd->bdev->bd_disk->async_events;

    add_disk(disk);

    pkt_sysfs_dev_new(pd);
    pkt_debugfs_dev_new(pd);

    pkt_devs[idx] = pd;
    if (pkt_dev)
        *pkt_dev = pd->pkt_dev;

    mutex_unlock(&ctl_mutex);
    return 0;

out_new_dev:
    blk_cleanup_queue(disk->queue);
out_mem2:
    put_disk(disk);
out_mem:
    if (pd->rb_pool)
        mempool_destroy(pd->rb_pool);
    kfree(pd);
out_mutex:
    mutex_unlock(&ctl_mutex);
    printk(DRIVER_NAME": setup of pktcdvd device failed\n");
    return ret;
}

/*
 * Tear down mapping from pktcdvd device to CD-ROM device.
 */
static int pkt_remove_dev(dev_t pkt_dev)
{
    struct pktcdvd_device *pd;
    int idx;
    int ret = 0;

    mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);

    for (idx = 0; idx < MAX_WRITERS; idx++) {
        pd = pkt_devs[idx];
        if (pd && (pd->pkt_dev == pkt_dev))
            break;
    }
    if (idx == MAX_WRITERS) {
        DPRINTK(DRIVER_NAME": dev not setup\n");
        ret = -ENXIO;
        goto out;
    }

    if (pd->refcnt > 0) {
        ret = -EBUSY;
        goto out;
    }
    if (!IS_ERR(pd->cdrw.thread))
        kthread_stop(pd->cdrw.thread);

    pkt_devs[idx] = NULL;

    pkt_debugfs_dev_remove(pd);
    pkt_sysfs_dev_remove(pd);

    blkdev_put(pd->bdev, FMODE_READ | FMODE_NDELAY);

    remove_proc_entry(pd->name, pkt_proc);
    DPRINTK(DRIVER_NAME": writer %s unmapped\n", pd->name);

    del_gendisk(pd->disk);
    blk_cleanup_queue(pd->disk->queue);
    put_disk(pd->disk);

    mempool_destroy(pd->rb_pool);
    kfree(pd);

    /* This is safe: open() is still holding a reference. */
    module_put(THIS_MODULE);

out:
    mutex_unlock(&ctl_mutex);
    return ret;
}

static void pkt_get_status(struct pkt_ctrl_command *ctrl_cmd)
{
    struct pktcdvd_device *pd;

    mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);

    pd = pkt_find_dev_from_minor(ctrl_cmd->dev_index);
    if (pd) {
        ctrl_cmd->dev = new_encode_dev(pd->bdev->bd_dev);
        ctrl_cmd->pkt_dev = new_encode_dev(pd->pkt_dev);
    } else {
        ctrl_cmd->dev = 0;
        ctrl_cmd->pkt_dev = 0;
    }
    ctrl_cmd->num_devices = MAX_WRITERS;

    mutex_unlock(&ctl_mutex);
}

static long pkt_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    struct pkt_ctrl_command ctrl_cmd;
    int ret = 0;
    dev_t pkt_dev = 0;

    if (cmd != PACKET_CTRL_CMD)
        return -ENOTTY;

    if (copy_from_user(&ctrl_cmd, argp, sizeof(struct pkt_ctrl_command)))
        return -EFAULT;

    switch (ctrl_cmd.command) {
    case PKT_CTRL_CMD_SETUP:
        if (!capable(CAP_SYS_ADMIN))
            return -EPERM;
        ret = pkt_setup_dev(new_decode_dev(ctrl_cmd.dev), &pkt_dev);
        ctrl_cmd.pkt_dev = new_encode_dev(pkt_dev);
        break;
    case PKT_CTRL_CMD_TEARDOWN:
        if (!capable(CAP_SYS_ADMIN))
            return -EPERM;
        ret = pkt_remove_dev(new_decode_dev(ctrl_cmd.pkt_dev));
        break;
    case PKT_CTRL_CMD_STATUS:
        pkt_get_status(&ctrl_cmd);
        break;
    default:
        return -ENOTTY;
    }

    if (copy_to_user(argp, &ctrl_cmd, sizeof(struct pkt_ctrl_command)))
        return -EFAULT;
    return ret;
}

#ifdef CONFIG_COMPAT
static long pkt_ctl_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    return pkt_ctl_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
}
#endif

static const struct file_operations pkt_ctl_fops = {
    .open       = nonseekable_open,
    .unlocked_ioctl = pkt_ctl_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = pkt_ctl_compat_ioctl,
#endif
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
};

static struct miscdevice pkt_misc = {
    .minor      = MISC_DYNAMIC_MINOR,
    .name       = DRIVER_NAME,
    .nodename   = "pktcdvd/control",
    .fops       = &pkt_ctl_fops
};

static int __init pkt_init(void)
{
    int ret;

    mutex_init(&ctl_mutex);

    psd_pool = mempool_create_kmalloc_pool(PSD_POOL_SIZE,
                    sizeof(struct packet_stacked_data));
    if (!psd_pool)
        return -ENOMEM;

    ret = register_blkdev(pktdev_major, DRIVER_NAME);
    if (ret < 0) {
        printk(DRIVER_NAME": Unable to register block device\n");
        goto out2;
    }
    if (!pktdev_major)
        pktdev_major = ret;

    ret = pkt_sysfs_init();
    if (ret)
        goto out;

    pkt_debugfs_init();

    ret = misc_register(&pkt_misc);
    if (ret) {
        printk(DRIVER_NAME": Unable to register misc device\n");
        goto out_misc;
    }

    pkt_proc = proc_mkdir("driver/"DRIVER_NAME, NULL);

    return 0;

out_misc:
    pkt_debugfs_cleanup();
    pkt_sysfs_cleanup();
out:
    unregister_blkdev(pktdev_major, DRIVER_NAME);
out2:
    mempool_destroy(psd_pool);
    return ret;
}

static void __exit pkt_exit(void)
{
    remove_proc_entry("driver/"DRIVER_NAME, NULL);
    misc_deregister(&pkt_misc);

    pkt_debugfs_cleanup();
    pkt_sysfs_cleanup();

    unregister_blkdev(pktdev_major, DRIVER_NAME);
    mempool_destroy(psd_pool);
}

MODULE_DESCRIPTION("Packet writing layer for CD/DVD drives");
MODULE_AUTHOR("Jens Axboe <[email protected]>");
MODULE_LICENSE("GPL");

module_init(pkt_init);
module_exit(pkt_exit);