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pktcdvd.c

/*
 * Copyright (C) 2000 Jens Axboe <axboe@suse.de>
 * Copyright (C) 2001-2004 Peter Osterlund <petero2@telia.com>
 * Copyright (C) 2006 Thomas Maier <balagi@justmail.de>
 *
 * 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/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 <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 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; /* /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;
      p = kzalloc(sizeof(*p), GFP_KERNEL);
      if (!p)
            return NULL;
      kobject_set_name(&p->kobj, "%s", name);
      p->kobj.parent = parent;
      p->kobj.ktype = ktype;
      p->pd = pd;
      if (kobject_register(&p->kobj) != 0) {
            kobject_put(&p->kobj);
            return NULL;
      }
      return p;
}
/*
 * remove a pktcdvd kernel object.
 */
static void pkt_kobj_remove(struct pktcdvd_kobj *p)
{
      if (p)
            kobject_unregister(&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 <balagi@justmail.de>
 *
 **********************************************************/

#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 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->clsdev = class_device_create(class_pktcdvd,
                              NULL, pd->pkt_dev,
                              NULL, "%s", pd->name);
            if (IS_ERR(pd->clsdev))
                  pd->clsdev = NULL;
      }
      if (pd->clsdev) {
            pd->kobj_stat = pkt_kobj_create(pd, "stat",
                              &pd->clsdev->kobj,
                              &kobj_pkt_type_stat);
            pd->kobj_wqueue = pkt_kobj_create(pd, "write_queue",
                              &pd->clsdev->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)
            class_device_destroy(class_pktcdvd, pd->pkt_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, 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, 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, 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

  /debugfs/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);
      }
}

static void pkt_bio_destructor(struct bio *bio)
{
      kfree(bio->bi_io_vec);
      kfree(bio);
}

static struct bio *pkt_bio_alloc(int nr_iovecs)
{
      struct bio_vec *bvl = NULL;
      struct bio *bio;

      bio = kmalloc(sizeof(struct bio), GFP_KERNEL);
      if (!bio)
            goto no_bio;
      bio_init(bio);

      bvl = kcalloc(nr_iovecs, sizeof(struct bio_vec), GFP_KERNEL);
      if (!bvl)
            goto no_bvl;

      bio->bi_max_vecs = nr_iovecs;
      bio->bi_io_vec = bvl;
      bio->bi_destructor = pkt_bio_destructor;

      return bio;

 no_bvl:
      kfree(bio);
 no_bio:
      return NULL;
}

/*
 * 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 = pkt_bio_alloc(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);

      for (i = 0; i < frames; i++) {
            struct bio *bio = pkt_bio_alloc(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++;
}

/*
 * Add a bio to a single linked list defined by its head and tail pointers.
 */
static void pkt_add_list_last(struct bio *bio, struct bio **list_head, struct bio **list_tail)
{
      bio->bi_next = NULL;
      if (*list_tail) {
            BUG_ON((*list_head) == NULL);
            (*list_tail)->bi_next = bio;
            (*list_tail) = bio;
      } else {
            BUG_ON((*list_head) != NULL);
            (*list_head) = bio;
            (*list_tail) = bio;
      }
}

/*
 * Remove and return the first bio from a single linked list defined by its
 * head and tail pointers.
 */
static inline struct bio *pkt_get_list_first(struct bio **list_head, struct bio **list_tail)
{
      struct bio *bio;

      if (*list_head == NULL)
            return NULL;

      bio = *list_head;
      *list_head = bio->bi_next;
      if (*list_head == NULL)
            *list_tail = NULL;

      bio->bi_next = NULL;
      return bio;
}

/*
 * 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);
      if (sizeof(rq->cmd) > CDROM_PACKET_SIZE)
            memset(rq->cmd + CDROM_PACKET_SIZE, 0, sizeof(rq->cmd) - CDROM_PACKET_SIZE);

      rq->timeout = 60*HZ;
      rq->cmd_type = REQ_TYPE_BLOCK_PC;
      rq->cmd_flags |= REQ_HARDBARRIER;
      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 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) {
            pkt_add_list_last(bio, &pd->iosched.read_queue,
                          &pd->iosched.read_queue_tail);
      } else {
            pkt_add_list_last(bio, &pd->iosched.write_queue,
                          &pd->iosched.write_queue_tail);
      }
      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 = (pd->iosched.read_queue != NULL);
            writes_queued = (pd->iosched.write_queue != NULL);
            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 = 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 = pkt_get_list_first(&pd->iosched.write_queue,
                                     &pd->iosched.write_queue_tail);
            } else {
                  bio = pkt_get_list_first(&pd->iosched.read_queue,
                                     &pd->iosched.read_queue_tail);
            }
            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 <= q->max_phys_segments) {
            /*
             * 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 <= q->max_phys_segments) {
            /*
             * 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, KM_USER0) +
                  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, KM_USER0);

            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, KM_USER0) + bvec[f].bv_offset;
                  void *vto = page_address(pkt->pages[p]) + offs;
                  memcpy(vto, vfrom, CD_FRAMESIZE);
                  kunmap_atomic(vfrom, KM_USER0);
                  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(!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);
      for (bio = pkt->orig_bios; bio; bio = bio->bi_next) {
            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++) {
            struct bio_vec *vec;

            int p, offset;
            if (written[f])
                  continue;
            bio = pkt->r_bios[f];
            vec = bio->bi_io_vec;
            bio_init(bio);
            bio->bi_max_vecs = 1;
            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;
            bio->bi_io_vec = vec;
            bio->bi_destructor = pkt_bio_destructor;

            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 || !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 != (1 << BIO_RW));
      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);
            pkt_add_list_last(bio, &pkt->orig_bios, &pkt->orig_bios_tail);
            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, WRITE);

      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);
      for (bio = pkt->orig_bios; bio; bio = bio->bi_next) {
            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_init(pkt->w_bio);
      pkt->w_bio->bi_max_vecs = PACKET_MAX_SIZE;
      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;
      pkt->w_bio->bi_io_vec = bvec;
      pkt->w_bio->bi_destructor = pkt_bio_destructor;
      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, *next;

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

      /* Finish all bios corresponding to this packet */
      bio = pkt->orig_bios;
      while (bio) {
            next = bio->bi_next;
            bio->bi_next = NULL;
            bio_endio(bio, uptodate ? 0 : -EIO);
            bio = next;
      }
      pkt->orig_bios = pkt->orig_bios_tail = NULL;
}

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;
                  }

                  generic_unplug_device(bdev_get_queue(pd->bdev));

                  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 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 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 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 int pkt_write_caching(struct pktcdvd_device *pd, int set)
{
      struct packet_command cgc;
      struct request_sense sense;
      unsigned char buf[64];
      int ret;

      memset(buf, 0, sizeof(buf));
      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 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;

      memset(buf, 0, sizeof(buf));
      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 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 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, int 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, O_RDONLY)))
            goto out;

      if ((ret = bd_claim(pd->bdev, pd)))
            goto out_putdev;

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

      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_unclaim;
            /*
             * 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_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_unclaim;

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

      return 0;

out_unclaim:
      bd_release(pd->bdev);
out_putdev:
      blkdev_put(pd->bdev);
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);
      bd_release(pd->bdev);
      blkdev_put(pd->bdev);

      pkt_shrink_pktlist(pd);
}

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

static int pkt_open(struct inode *inode, struct file *file)
{
      struct pktcdvd_device *pd = NULL;
      int ret;

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

      mutex_lock(&ctl_mutex);
      pd = pkt_find_dev_from_minor(iminor(inode));
      if (!pd) {
            ret = -ENODEV;
            goto out;
      }
      BUG_ON(pd->refcnt < 0);

      pd->refcnt++;
      if (pd->refcnt > 1) {
            if ((file->f_mode & FMODE_WRITE) &&
                !test_bit(PACKET_WRITABLE, &pd->flags)) {
                  ret = -EBUSY;
                  goto out_dec;
            }
      } else {
            ret = pkt_open_dev(pd, file->f_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(inode->i_bdev, CD_FRAMESIZE);
      }

      mutex_unlock(&ctl_mutex);
      return 0;

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

static int pkt_close(struct inode *inode, struct file *file)
{
      struct pktcdvd_device *pd = inode->i_bdev->bd_disk->private_data;
      int ret = 0;

      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);
      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 int 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 0;
      }

      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, bio_split_pool, first_sectors);
                  BUG_ON(!bp);
                  pkt_make_request(q, &bp->bio1);
                  pkt_make_request(q, &bp->bio2);
                  bio_pair_release(bp);
                  return 0;
            }
      }

      /*
       * 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)) {
                        pkt_add_list_last(bio, &pkt->orig_bios,
                                      &pkt->orig_bios_tail);
                        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 0;
                  } 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, WRITE);
            do {
                  spin_unlock(&pd->lock);
                  congestion_wait(WRITE, 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 0;
end_io:
      bio_io_error(bio);
      return 0;
}



static int pkt_merge_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *bvec)
{
      struct pktcdvd_device *pd = q->queuedata;
      sector_t zone = ZONE(bio->bi_sector, pd);
      int used = ((bio->bi_sector - zone) << 9) + bio->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 - bio->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_hardsect_size(q, CD_FRAMESIZE);
      blk_queue_max_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 proc_dir_entry *proc;
      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, O_RDONLY | O_NONBLOCK);
      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_proc_entry(pd->name, 0, pkt_proc);
      if (proc) {
            proc->data = pd;
            proc->proc_fops = &pkt_proc_fops;
      }
      DPRINTK(DRIVER_NAME": writer %s mapped to %s\n", pd->name, bdevname(bdev, b));
      return 0;

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

static int pkt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
      struct pktcdvd_device *pd = inode->i_bdev->bd_disk->private_data;

      VPRINTK("pkt_ioctl: cmd %x, dev %d:%d\n", cmd, imajor(inode), iminor(inode));

      switch (cmd) {
      /*
       * 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:
            return blkdev_ioctl(pd->bdev->bd_inode, file, cmd, arg);

      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);
            return blkdev_ioctl(pd->bdev->bd_inode, file, cmd, arg);

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

      return 0;
}

static int pkt_media_changed(struct gendisk *disk)
{
      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)
            return 0;
      return attached_disk->fops->media_changed(attached_disk);
}

static struct block_device_operations pktcdvd_ops = {
      .owner =          THIS_MODULE,
      .open =                 pkt_open,
      .release =        pkt_close,
      .ioctl =          pkt_ioctl,
      .media_changed =  pkt_media_changed,
};

/*
 * 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);
      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->private_data = pd;
      disk->queue = blk_alloc_queue(GFP_KERNEL);
      if (!disk->queue)
            goto out_mem2;

      pd->pkt_dev = MKDEV(disk->major, disk->first_minor);
      ret = pkt_new_dev(pd, dev);
      if (ret)
            goto out_new_dev;

      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);

      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 int pkt_ctl_ioctl(struct inode *inode, 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;
}


static const struct file_operations pkt_ctl_fops = {
      .ioctl       = pkt_ctl_ioctl,
      .owner       = THIS_MODULE,
};

static struct miscdevice pkt_misc = {
      .minor            = MISC_DYNAMIC_MINOR,
      .name             = DRIVER_NAME,
      .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_NAME, proc_root_driver);

      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_NAME, proc_root_driver);
      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 <axboe@suse.de>");
MODULE_LICENSE("GPL");

module_init(pkt_init);
module_exit(pkt_exit);

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