/*
   * 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 ->submit_bio 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.

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

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/pktcdvd.h>

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/compat.h>

  #include <linux/kthread.h>
  #include <linux/errno.h>
  #include <linux/spinlock.h>
  #include <linux/file.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/miscdevice.h>

  #include <linux/freezer.h>

  #include <linux/mutex.h>

  #include <linux/slab.h>

  #include <linux/backing-dev.h>

  #include <scsi/scsi_cmnd.h>
  #include <scsi/scsi_ioctl.h>

  #include <scsi/scsi.h>

  #include <linux/debugfs.h>
  #include <linux/device.h>

  #include <linux/nospec.h>

  #include <linux/uaccess.h>

  #define DRIVER_NAME	"pktcdvd"

  #define pkt_err(pd, fmt, ...)						\
  	pr_err("%s: " fmt, pd->name, ##__VA_ARGS__)

  #define pkt_notice(pd, fmt, ...)					\
  	pr_notice("%s: " fmt, pd->name, ##__VA_ARGS__)

  #define pkt_info(pd, fmt, ...)						\
  	pr_info("%s: " fmt, pd->name, ##__VA_ARGS__)

  #define pkt_dbg(level, pd, fmt, ...)					\
  do {									\
  	if (level == 2 && PACKET_DEBUG >= 2)				\
  		pr_notice("%s: %s():" fmt,				\
  			  pd->name, __func__, ##__VA_ARGS__);		\
  	else if (level == 1 && PACKET_DEBUG >= 1)			\
  		pr_notice("%s: " fmt, pd->name, ##__VA_ARGS__);		\

  } while (0)

  
  #define MAX_SPEED 0xffff

  static DEFINE_MUTEX(pktcdvd_mutex);

  static struct pktcdvd_device *pkt_devs[MAX_WRITERS];
  static struct proc_dir_entry *pkt_proc;

  static int pktdev_major;

  static int write_congestion_on  = PKT_WRITE_CONGESTION_ON;
  static int write_congestion_off = PKT_WRITE_CONGESTION_OFF;

  static struct mutex ctl_mutex;	/* Serialize open/close/setup/teardown */

  static mempool_t psd_pool;
  static struct bio_set pkt_bio_set;

  static struct class	*class_pktcdvd = NULL;    /* /sys/class/pktcdvd */

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

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

  static sector_t get_zone(sector_t sector, struct pktcdvd_device *pd)
  {
  	return (sector + pd->offset) & ~(sector_t)(pd->settings.size - 1);
  }

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

  	int error;

  	p = kzalloc(sizeof(*p), GFP_KERNEL);
  	if (!p)
  		return NULL;

  	p->pd = pd;

  	error = kobject_init_and_add(&p->kobj, ktype, parent, "%s", name);
  	if (error) {

  		kobject_put(&p->kobj);

  		return NULL;

  	}

  	kobject_uevent(&p->kobj, KOBJ_ADD);

  	return p;
  }
  /*
   * remove a pktcdvd kernel object.
   */
  static void pkt_kobj_remove(struct pktcdvd_kobj *p)
  {
  	if (p)

  		kobject_put(&p->kobj);

  }
  /*
   * default release function for pktcdvd kernel objects.
   */
  static void pkt_kobj_release(struct kobject *kobj)
  {
  	kfree(to_pktcdvdkobj(kobj));
  }
  
  
  /**********************************************************
   *
   * sysfs interface for pktcdvd
   * by (C) 2006  Thomas Maier <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
  ", pd->stats.pkt_started);
  
  	} else if (strcmp(attr->name, "packets_finished") == 0) {
  		n = sprintf(data, "%lu
  ", pd->stats.pkt_ended);
  
  	} else if (strcmp(attr->name, "kb_written") == 0) {
  		n = sprintf(data, "%lu
  ", pd->stats.secs_w >> 1);
  
  	} else if (strcmp(attr->name, "kb_read") == 0) {
  		n = sprintf(data, "%lu
  ", pd->stats.secs_r >> 1);
  
  	} else if (strcmp(attr->name, "kb_read_gather") == 0) {
  		n = sprintf(data, "%lu
  ", 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
  ", 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
  ", 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
  ", v);
  	}
  	return n;
  }
  
  static void init_write_congestion_marks(int* lo, int* hi)
  {
  	if (*hi > 0) {
  		*hi = max(*hi, 500);
  		*hi = min(*hi, 1000000);
  		if (*lo <= 0)
  			*lo = *hi - 100;
  		else {
  			*lo = min(*lo, *hi - 100);
  			*lo = max(*lo, 100);
  		}
  	} else {
  		*hi = -1;
  		*lo = -1;
  	}
  }
  
  static ssize_t kobj_pkt_store(struct kobject *kobj,
  			struct attribute *attr,
  			const char *data, size_t len)
  {
  	struct pktcdvd_device *pd = to_pktcdvdkobj(kobj)->pd;
  	int val;

  	if (strcmp(attr->name, "reset") == 0 && len > 0) {

  		pd->stats.pkt_started = 0;
  		pd->stats.pkt_ended = 0;
  		pd->stats.secs_w = 0;
  		pd->stats.secs_rg = 0;
  		pd->stats.secs_r = 0;
  
  	} else if (strcmp(attr->name, "congestion_off") == 0

  		   && sscanf(data, "%d", &val) == 1) {

  		spin_lock(&pd->lock);
  		pd->write_congestion_off = val;
  		init_write_congestion_marks(&pd->write_congestion_off,
  					&pd->write_congestion_on);
  		spin_unlock(&pd->lock);
  
  	} else if (strcmp(attr->name, "congestion_on") == 0

  		   && sscanf(data, "%d", &val) == 1) {

  		spin_lock(&pd->lock);
  		pd->write_congestion_on = val;
  		init_write_congestion_marks(&pd->write_congestion_off,
  					&pd->write_congestion_on);
  		spin_unlock(&pd->lock);
  	}
  	return len;
  }

  static const struct sysfs_ops kobj_pkt_ops = {

  	.show = kobj_pkt_show,
  	.store = kobj_pkt_store
  };
  static struct kobj_type kobj_pkt_type_stat = {
  	.release = pkt_kobj_release,
  	.sysfs_ops = &kobj_pkt_ops,
  	.default_attrs = kobj_pkt_attrs_stat
  };
  static struct kobj_type kobj_pkt_type_wqueue = {
  	.release = pkt_kobj_release,
  	.sysfs_ops = &kobj_pkt_ops,
  	.default_attrs = kobj_pkt_attrs_wqueue
  };
  
  static void pkt_sysfs_dev_new(struct pktcdvd_device *pd)
  {
  	if (class_pktcdvd) {

  		pd->dev = device_create(class_pktcdvd, NULL, MKDEV(0, 0), NULL,

  					"%s", pd->name);

  		if (IS_ERR(pd->dev))
  			pd->dev = NULL;

  	}

  	if (pd->dev) {

  		pd->kobj_stat = pkt_kobj_create(pd, "stat",

  					&pd->dev->kobj,

  					&kobj_pkt_type_stat);
  		pd->kobj_wqueue = pkt_kobj_create(pd, "write_queue",

  					&pd->dev->kobj,

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

  		device_unregister(pd->dev);

  }
  
  
  /********************************************************************
    /sys/class/pktcdvd/
                       add            map block device
                       remove         unmap packet dev
                       device_map     show mappings
   *******************************************************************/
  
  static void class_pktcdvd_release(struct class *cls)
  {
  	kfree(cls);
  }

  
  static ssize_t device_map_show(struct class *c, struct class_attribute *attr,
  			       char *data)

  {
  	int n = 0;
  	int idx;
  	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
  	for (idx = 0; idx < MAX_WRITERS; idx++) {
  		struct pktcdvd_device *pd = pkt_devs[idx];
  		if (!pd)
  			continue;
  		n += sprintf(data+n, "%s %u:%u %u:%u
  ",
  			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 CLASS_ATTR_RO(device_map);

  static ssize_t add_store(struct class *c, struct class_attribute *attr,
  			 const char *buf, size_t count)

  {
  	unsigned int major, minor;

  	if (sscanf(buf, "%u:%u", &major, &minor) == 2) {

  		/* pkt_setup_dev() expects caller to hold reference to self */
  		if (!try_module_get(THIS_MODULE))
  			return -ENODEV;

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

  
  		module_put(THIS_MODULE);

  		return count;
  	}

  	return -EINVAL;
  }

  static CLASS_ATTR_WO(add);

  static ssize_t remove_store(struct class *c, struct class_attribute *attr,
  			    const char *buf, size_t count)

  {
  	unsigned int major, minor;

  	if (sscanf(buf, "%u:%u", &major, &minor) == 2) {

  		pkt_remove_dev(MKDEV(major, minor));
  		return count;
  	}
  	return -EINVAL;
  }

  static CLASS_ATTR_WO(remove);

  static struct attribute *class_pktcdvd_attrs[] = {
  	&class_attr_add.attr,
  	&class_attr_remove.attr,
  	&class_attr_device_map.attr,
  	NULL,

  };

  ATTRIBUTE_GROUPS(class_pktcdvd);

  
  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_groups = class_pktcdvd_groups;

  	ret = class_register(class_pktcdvd);
  	if (ret) {
  		kfree(class_pktcdvd);
  		class_pktcdvd = NULL;

  		pr_err("failed to create class pktcdvd
  ");

  		return ret;
  	}
  	return 0;
  }
  
  static void pkt_sysfs_cleanup(void)
  {
  	if (class_pktcdvd)
  		class_destroy(class_pktcdvd);
  	class_pktcdvd = NULL;
  }
  
  /********************************************************************
    entries in debugfs

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

  			info
  
   *******************************************************************/
  
  static int pkt_debugfs_seq_show(struct seq_file *m, void *p)
  {
  	return pkt_seq_show(m, p);
  }
  
  static int pkt_debugfs_fops_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, pkt_debugfs_seq_show, inode->i_private);
  }

  static const struct file_operations debug_fops = {

  	.open		= pkt_debugfs_fops_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  	.owner		= THIS_MODULE,
  };
  
  static void pkt_debugfs_dev_new(struct pktcdvd_device *pd)
  {
  	if (!pkt_debugfs_root)
  		return;

  	pd->dfs_d_root = debugfs_create_dir(pd->name, pkt_debugfs_root);

  	if (!pd->dfs_d_root)

  		return;

  	pd->dfs_f_info = debugfs_create_file("info", 0444,
  					     pd->dfs_d_root, pd, &debug_fops);

  }
  
  static void pkt_debugfs_dev_remove(struct pktcdvd_device *pd)
  {
  	if (!pkt_debugfs_root)
  		return;

  	debugfs_remove(pd->dfs_f_info);
  	debugfs_remove(pd->dfs_d_root);

  	pd->dfs_f_info = NULL;

  	pd->dfs_d_root = NULL;
  }
  
  static void pkt_debugfs_init(void)
  {
  	pkt_debugfs_root = debugfs_create_dir(DRIVER_NAME, NULL);

  }
  
  static void pkt_debugfs_cleanup(void)
  {

  	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)) {

  		pkt_dbg(2, pd, "queue empty
  ");

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

  /*
   * Allocate a packet_data struct
   */

  static struct packet_data *pkt_alloc_packet_data(int frames)

  {
  	int i;
  	struct packet_data *pkt;

  	pkt = kzalloc(sizeof(struct packet_data), GFP_KERNEL);

  	if (!pkt)
  		goto no_pkt;

  	pkt->frames = frames;

  	pkt->w_bio = bio_kmalloc(GFP_KERNEL, frames);

  	if (!pkt->w_bio)
  		goto no_bio;

  	for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {

  		pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
  		if (!pkt->pages[i])
  			goto no_page;
  	}
  
  	spin_lock_init(&pkt->lock);

  	bio_list_init(&pkt->orig_bios);

  	for (i = 0; i < frames; i++) {

  		struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);

  		if (!bio)
  			goto no_rd_bio;

  		pkt->r_bios[i] = bio;
  	}
  
  	return pkt;
  
  no_rd_bio:

  	for (i = 0; i < frames; i++) {

  		struct bio *bio = pkt->r_bios[i];
  		if (bio)
  			bio_put(bio);
  	}
  
  no_page:

  	for (i = 0; i < frames / FRAMES_PER_PAGE; i++)

  		if (pkt->pages[i])
  			__free_page(pkt->pages[i]);
  	bio_put(pkt->w_bio);
  no_bio:
  	kfree(pkt);
  no_pkt:
  	return NULL;
  }
  
  /*
   * Free a packet_data struct
   */
  static void pkt_free_packet_data(struct packet_data *pkt)
  {
  	int i;

  	for (i = 0; i < pkt->frames; i++) {

  		struct bio *bio = pkt->r_bios[i];
  		if (bio)
  			bio_put(bio);
  	}

  	for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)

  		__free_page(pkt->pages[i]);
  	bio_put(pkt->w_bio);
  	kfree(pkt);
  }
  
  static void pkt_shrink_pktlist(struct pktcdvd_device *pd)
  {
  	struct packet_data *pkt, *next;
  
  	BUG_ON(!list_empty(&pd->cdrw.pkt_active_list));
  
  	list_for_each_entry_safe(pkt, next, &pd->cdrw.pkt_free_list, list) {
  		pkt_free_packet_data(pkt);
  	}

  	INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);

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

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

  	while (nr_packets > 0) {

  		pkt = pkt_alloc_packet_data(pd->settings.size >> 2);

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

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

  static void pkt_rbtree_erase(struct pktcdvd_device *pd, struct pkt_rb_node *node)

  {
  	rb_erase(&node->rb_node, &pd->bio_queue);

  	mempool_free(node, &pd->rb_pool);

  	pd->bio_queue_size--;
  	BUG_ON(pd->bio_queue_size < 0);
  }
  
  /*
   * Find the first node in the pd->bio_queue rb tree with a starting sector >= s.
   */
  static struct pkt_rb_node *pkt_rbtree_find(struct pktcdvd_device *pd, sector_t s)
  {
  	struct rb_node *n = pd->bio_queue.rb_node;
  	struct rb_node *next;
  	struct pkt_rb_node *tmp;
  
  	if (!n) {
  		BUG_ON(pd->bio_queue_size > 0);
  		return NULL;
  	}
  
  	for (;;) {
  		tmp = rb_entry(n, struct pkt_rb_node, rb_node);

  		if (s <= tmp->bio->bi_iter.bi_sector)

  			next = n->rb_left;
  		else
  			next = n->rb_right;
  		if (!next)
  			break;
  		n = next;
  	}

  	if (s > tmp->bio->bi_iter.bi_sector) {

  		tmp = pkt_rbtree_next(tmp);
  		if (!tmp)
  			return NULL;
  	}

  	BUG_ON(s > tmp->bio->bi_iter.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_iter.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_iter.bi_sector)

  			p = &(*p)->rb_left;
  		else
  			p = &(*p)->rb_right;
  	}
  	rb_link_node(&node->rb_node, parent, p);
  	rb_insert_color(&node->rb_node, &pd->bio_queue);
  	pd->bio_queue_size++;
  }
  
  /*

   * Send a packet_command to the underlying block device and
   * wait for completion.
   */
  static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *cgc)
  {

  	struct request_queue *q = bdev_get_queue(pd->bdev);

  	struct request *rq;

  	int ret = 0;
  
  	rq = blk_get_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?

  			     REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);

  	if (IS_ERR(rq))
  		return PTR_ERR(rq);

  
  	if (cgc->buflen) {

  		ret = blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen,

  				      GFP_NOIO);

  		if (ret)

  			goto out;
  	}

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

  	rq->timeout = 60*HZ;

  	if (cgc->quiet)

  		rq->rq_flags |= RQF_QUIET;

  	blk_execute_rq(rq->q, pd->bdev->bd_disk, rq, 0);

  	if (scsi_req(rq)->result)

  		ret = -EIO;

  out:

  	blk_put_request(rq);

  	return ret;

  }

  static const char *sense_key_string(__u8 index)
  {
  	static const char * const info[] = {
  		"No sense", "Recovered error", "Not ready",
  		"Medium error", "Hardware error", "Illegal request",
  		"Unit attention", "Data protect", "Blank check",
  	};
  
  	return index < ARRAY_SIZE(info) ? info[index] : "INVALID";
  }

  /*
   * A generic sense dump / resolve mechanism should be implemented across
   * all ATAPI + SCSI devices.
   */

  static void pkt_dump_sense(struct pktcdvd_device *pd,
  			   struct packet_command *cgc)

  {

  	struct scsi_sense_hdr *sshdr = cgc->sshdr;

  	if (sshdr)

  		pkt_err(pd, "%*ph - sense %02x.%02x.%02x (%s)
  ",
  			CDROM_PACKET_SIZE, cgc->cmd,

  			sshdr->sense_key, sshdr->asc, sshdr->ascq,
  			sense_key_string(sshdr->sense_key));

  	else

  		pkt_err(pd, "%*ph - no sense
  ", CDROM_PACKET_SIZE, cgc->cmd);

  }
  
  /*
   * flush the drive cache to media
   */
  static int pkt_flush_cache(struct pktcdvd_device *pd)
  {
  	struct packet_command cgc;
  
  	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
  	cgc.cmd[0] = GPCMD_FLUSH_CACHE;
  	cgc.quiet = 1;
  
  	/*
  	 * the IMMED bit -- we default to not setting it, although that
  	 * would allow a much faster close, this is safer
  	 */
  #if 0
  	cgc.cmd[1] = 1 << 1;
  #endif
  	return pkt_generic_packet(pd, &cgc);
  }
  
  /*
   * speed is given as the normal factor, e.g. 4 for 4x
   */

  static noinline_for_stack int pkt_set_speed(struct pktcdvd_device *pd,
  				unsigned write_speed, unsigned read_speed)

  {
  	struct packet_command cgc;

  	struct scsi_sense_hdr sshdr;

  	int ret;
  
  	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);

  	cgc.sshdr = &sshdr;

  	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;

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

  		pkt_dump_sense(pd, &cgc);

  
  	return ret;
  }
  
  /*
   * Queue a bio for processing by the low-level CD device. Must be called
   * from process context.
   */

  static void pkt_queue_bio(struct pktcdvd_device *pd, struct bio *bio)

  {
  	spin_lock(&pd->iosched.lock);

  	if (bio_data_dir(bio) == READ)
  		bio_list_add(&pd->iosched.read_queue, bio);
  	else
  		bio_list_add(&pd->iosched.write_queue, bio);

  	spin_unlock(&pd->iosched.lock);
  
  	atomic_set(&pd->iosched.attention, 1);
  	wake_up(&pd->wqueue);
  }
  
  /*
   * Process the queued read/write requests. This function handles special
   * requirements for CDRW drives:
   * - A cache flush command must be inserted before a read request if the
   *   previous request was a write.

   * - Switching between reading and writing is slow, so don't do it more often

   *   than necessary.

   * - Optimize for throughput at the expense of latency. This means that streaming
   *   writes will never be interrupted by a read, but if the drive has to seek
   *   before the next write, switch to reading instead if there are any pending
   *   read requests.

   * - Set the read speed according to current usage pattern. When only reading
   *   from the device, it's best to use the highest possible read speed, but
   *   when switching often between reading and writing, it's better to have the
   *   same read and write speeds.

   */
  static void pkt_iosched_process_queue(struct pktcdvd_device *pd)
  {

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

  	for (;;) {
  		struct bio *bio;

  		int reads_queued, writes_queued;

  
  		spin_lock(&pd->iosched.lock);

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

  		spin_unlock(&pd->iosched.lock);
  
  		if (!reads_queued && !writes_queued)
  			break;
  
  		if (pd->iosched.writing) {

  			int need_write_seek = 1;
  			spin_lock(&pd->iosched.lock);

  			bio = bio_list_peek(&pd->iosched.write_queue);

  			spin_unlock(&pd->iosched.lock);

  			if (bio && (bio->bi_iter.bi_sector ==
  				    pd->iosched.last_write))

  				need_write_seek = 0;
  			if (need_write_seek && reads_queued) {

  				if (atomic_read(&pd->cdrw.pending_bios) > 0) {

  					pkt_dbg(2, pd, "write, waiting
  ");

  					break;
  				}
  				pkt_flush_cache(pd);
  				pd->iosched.writing = 0;
  			}
  		} else {
  			if (!reads_queued && writes_queued) {
  				if (atomic_read(&pd->cdrw.pending_bios) > 0) {

  					pkt_dbg(2, pd, "read, waiting
  ");

  					break;
  				}
  				pd->iosched.writing = 1;
  			}
  		}
  
  		spin_lock(&pd->iosched.lock);

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

  		spin_unlock(&pd->iosched.lock);
  
  		if (!bio)
  			continue;
  
  		if (bio_data_dir(bio) == READ)

  			pd->iosched.successive_reads +=
  				bio->bi_iter.bi_size >> 10;

  		else {

  			pd->iosched.successive_reads = 0;

  			pd->iosched.last_write = bio_end_sector(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);

  		submit_bio_noacct(bio);

  	}
  }
  
  /*
   * Special care is needed if the underlying block device has a small
   * max_phys_segments value.
   */

  static int pkt_set_segment_merging(struct pktcdvd_device *pd, struct request_queue *q)

  {

  	if ((pd->settings.size << 9) / CD_FRAMESIZE

  	    <= queue_max_segments(q)) {

  		/*
  		 * The cdrom device can handle one segment/frame
  		 */
  		clear_bit(PACKET_MERGE_SEGS, &pd->flags);
  		return 0;

  	} else if ((pd->settings.size << 9) / PAGE_SIZE

  		   <= queue_max_segments(q)) {

  		/*
  		 * We can handle this case at the expense of some extra memory
  		 * copies during write operations
  		 */
  		set_bit(PACKET_MERGE_SEGS, &pd->flags);
  		return 0;
  	} else {

  		pkt_err(pd, "cdrom max_phys_segments too small
  ");

  		return -EIO;
  	}
  }

  static void pkt_end_io_read(struct bio *bio)

  {
  	struct packet_data *pkt = bio->bi_private;
  	struct pktcdvd_device *pd = pkt->pd;
  	BUG_ON(!pd);

  	pkt_dbg(2, pd, "bio=%p sec0=%llx sec=%llx err=%d
  ",

  		bio, (unsigned long long)pkt->sector,

  		(unsigned long long)bio->bi_iter.bi_sector, bio->bi_status);

  	if (bio->bi_status)

  		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)

  {
  	struct packet_data *pkt = bio->bi_private;
  	struct pktcdvd_device *pd = pkt->pd;
  	BUG_ON(!pd);

  	pkt_dbg(2, pd, "id=%d, err=%d
  ", pkt->id, bio->bi_status);

  
  	pd->stats.pkt_ended++;
  
  	pkt_bio_finished(pd);
  	atomic_dec(&pkt->io_wait);
  	atomic_inc(&pkt->run_sm);
  	wake_up(&pd->wqueue);

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

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

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

  	/*
  	 * Figure out which frames we need to read before we can write.
  	 */
  	memset(written, 0, sizeof(written));
  	spin_lock(&pkt->lock);

  	bio_list_for_each(bio, &pkt->orig_bios) {

  		int first_frame = (bio->bi_iter.bi_sector - pkt->sector) /
  			(CD_FRAMESIZE >> 9);
  		int num_frames = bio->bi_iter.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) {

  		pkt_dbg(2, pd, "zone %llx cached
  ",

  			(unsigned long long)pkt->sector);
  		goto out_account;
  	}

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

  		if (written[f])
  			continue;

  		bio = pkt->r_bios[f];

  		bio_reset(bio);

  		bio->bi_iter.bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);

  		bio_set_dev(bio, pd->bdev);

  		bio->bi_end_io = pkt_end_io_read;
  		bio->bi_private = pkt;
  
  		p = (f * CD_FRAMESIZE) / PAGE_SIZE;
  		offset = (f * CD_FRAMESIZE) % PAGE_SIZE;

  		pkt_dbg(2, pd, "Adding frame %d, page:%p offs:%d
  ",

  			f, pkt->pages[p], offset);
  		if (!bio_add_page(bio, pkt->pages[p], CD_FRAMESIZE, offset))
  			BUG();
  
  		atomic_inc(&pkt->io_wait);

  		bio_set_op_attrs(bio, REQ_OP_READ, 0);

  		pkt_queue_bio(pd, bio);

  		frames_read++;
  	}
  
  out_account:

  	pkt_dbg(2, pd, "need %d frames for zone %llx
  ",

  		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);
  	}
  }

  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;

  	pkt_dbg(2, pd, "pkt %2d : s=%6llx %s -> %s
  ",

  		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;

  	atomic_set(&pd->scan_queue, 0);
  
  	if (list_empty(&pd->cdrw.pkt_free_list)) {

  		pkt_dbg(2, pd, "no pkt
  ");

  		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 = get_zone(bio->bi_iter.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) {

  		pkt_dbg(2, pd, "no bio
  ");

  		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);

  	pkt_dbg(2, pd, "looking for zone %llx
  ", (unsigned long long)zone);

  	while ((node = pkt_rbtree_find(pd, zone)) != NULL) {
  		bio = node->bio;

  		pkt_dbg(2, pd, "found zone=%llx
  ", (unsigned long long)
  			get_zone(bio->bi_iter.bi_sector, pd));
  		if (get_zone(bio->bi_iter.bi_sector, pd) != zone)

  			break;
  		pkt_rbtree_erase(pd, node);
  		spin_lock(&pkt->lock);

  		bio_list_add(&pkt->orig_bios, bio);

  		pkt->write_size += bio->bi_iter.bi_size / CD_FRAMESIZE;

  		spin_unlock(&pkt->lock);
  	}

  	/* check write congestion marks, and if bio_queue_size is
  	   below, wake up any waiters */
  	wakeup = (pd->write_congestion_on > 0
  	 		&& pd->bio_queue_size <= pd->write_congestion_off);

  	spin_unlock(&pd->lock);

  	if (wakeup) {

  		clear_bdi_congested(pd->disk->queue->backing_dev_info,

  					BLK_RW_ASYNC);
  	}

  
  	pkt->sleep_time = max(PACKET_WAIT_TIME, 1);
  	pkt_set_state(pkt, PACKET_WAITING_STATE);
  	atomic_set(&pkt->run_sm, 1);
  
  	spin_lock(&pd->cdrw.active_list_lock);
  	list_add(&pkt->list, &pd->cdrw.pkt_active_list);
  	spin_unlock(&pd->cdrw.active_list_lock);
  
  	return 1;
  }
  
  /*
   * Assemble a bio to write one packet and queue the bio for processing
   * by the underlying block device.
   */
  static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
  {

  	int f;

  	bio_reset(pkt->w_bio);

  	pkt->w_bio->bi_iter.bi_sector = pkt->sector;

  	bio_set_dev(pkt->w_bio, pd->bdev);

  	pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
  	pkt->w_bio->bi_private = pkt;
  
  	/* XXX: locking? */

  	for (f = 0; f < pkt->frames; f++) {

  		struct page *page = pkt->pages[(f * CD_FRAMESIZE) / PAGE_SIZE];
  		unsigned offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
  
  		if (!bio_add_page(pkt->w_bio, page, CD_FRAMESIZE, offset))

  			BUG();

  	}

  	pkt_dbg(2, pd, "vcnt=%d
  ", pkt->w_bio->bi_vcnt);

  
  	/*

  	 * Fill-in bvec with data from orig_bios.

  	 */

  	spin_lock(&pkt->lock);

  	bio_list_copy_data(pkt->w_bio, pkt->orig_bios.head);

  	pkt_set_state(pkt, PACKET_WRITE_WAIT_STATE);
  	spin_unlock(&pkt->lock);

  	pkt_dbg(2, pd, "Writing %d frames for zone %llx
  ",

  		pkt->write_size, (unsigned long long)pkt->sector);

  	if (test_bit(PACKET_MERGE_SEGS, &pd->flags) || (pkt->write_size < pkt->frames))

  		pkt->cache_valid = 1;

  	else

  		pkt->cache_valid = 0;

  
  	/* Start the write request */

  	atomic_set(&pkt->io_wait, 1);

  	bio_set_op_attrs(pkt->w_bio, REQ_OP_WRITE, 0);

  	pkt_queue_bio(pd, pkt->w_bio);

  }

  static void pkt_finish_packet(struct packet_data *pkt, blk_status_t status)

  {

  	struct bio *bio;

  	if (status)

  		pkt->cache_valid = 0;
  
  	/* Finish all bios corresponding to this packet */

  	while ((bio = bio_list_pop(&pkt->orig_bios))) {

  		bio->bi_status = status;

  		bio_endio(bio);
  	}

  }
  
  static void pkt_run_state_machine(struct pktcdvd_device *pd, struct packet_data *pkt)
  {

  	pkt_dbg(2, pd, "pkt %d
  ", 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 (!pkt->w_bio->bi_status) {

  				pkt_set_state(pkt, PACKET_FINISHED_STATE);
  			} else {
  				pkt_set_state(pkt, PACKET_RECOVERY_STATE);
  			}
  			break;
  
  		case PACKET_RECOVERY_STATE:

  			pkt_dbg(2, pd, "No recovery possible
  ");
  			pkt_set_state(pkt, PACKET_FINISHED_STATE);

  			break;
  
  		case PACKET_FINISHED_STATE:

  			pkt_finish_packet(pkt, pkt->w_bio->bi_status);

  			return;
  
  		default:
  			BUG();
  			break;
  		}
  	}
  }
  
  static void pkt_handle_packets(struct pktcdvd_device *pd)
  {
  	struct packet_data *pkt, *next;

  	/*
  	 * 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, MIN_NICE);

  	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);

  				pkt_dbg(2, pd, "i:%d ow:%d rw:%d ww:%d rec:%d fin:%d
  ",

  					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;
  			}

  			pkt_dbg(2, pd, "sleeping
  ");

  			residue = schedule_timeout(min_sleep_time);

  			pkt_dbg(2, pd, "wake up
  ");

  
  			/* 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)
  {

  	pkt_info(pd, "%s packets, %u blocks, Mode-%c disc
  ",
  		 pd->settings.fp ? "Fixed" : "Variable",
  		 pd->settings.size >> 2,
  		 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;

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

  		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;

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

  		return ret;
  
  	cgc.buflen = be16_to_cpu(ti->track_information_length) +
  		     sizeof(ti->track_information_length);
  
  	if (cgc.buflen > sizeof(track_information))
  		cgc.buflen = sizeof(track_information);
  
  	cgc.cmd[8] = cgc.buflen;
  	return pkt_generic_packet(pd, &cgc);
  }

  static noinline_for_stack int pkt_get_last_written(struct pktcdvd_device *pd,
  						long *last_written)

  {
  	disc_information di;
  	track_information ti;
  	__u32 last_track;

  	int ret;

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

  		return ret;
  
  	last_track = (di.last_track_msb << 8) | di.last_track_lsb;

  	ret = pkt_get_track_info(pd, last_track, 1, &ti);
  	if (ret)

  		return ret;
  
  	/* if this track is blank, try the previous. */
  	if (ti.blank) {
  		last_track--;

  		ret = pkt_get_track_info(pd, last_track, 1, &ti);
  		if (ret)

  			return ret;
  	}
  
  	/* if last recorded field is valid, return it. */
  	if (ti.lra_v) {
  		*last_written = be32_to_cpu(ti.last_rec_address);
  	} else {
  		/* make it up instead */
  		*last_written = be32_to_cpu(ti.track_start) +
  				be32_to_cpu(ti.track_size);
  		if (ti.free_blocks)
  			*last_written -= (be32_to_cpu(ti.free_blocks) + 7);
  	}
  	return 0;
  }
  
  /*
   * write mode select package based on pd->settings
   */

  static noinline_for_stack int pkt_set_write_settings(struct pktcdvd_device *pd)

  {
  	struct packet_command cgc;

  	struct scsi_sense_hdr sshdr;

  	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.sshdr = &sshdr;

  	ret = pkt_mode_sense(pd, &cgc, GPMODE_WRITE_PARMS_PAGE, 0);
  	if (ret) {

  		pkt_dump_sense(pd, &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.sshdr = &sshdr;

  	ret = pkt_mode_sense(pd, &cgc, GPMODE_WRITE_PARMS_PAGE, 0);
  	if (ret) {

  		pkt_dump_sense(pd, &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
  		 */

  		pkt_err(pd, "write mode wrong %d
  ", wp->data_block_type);

  		return 1;
  	}
  	wp->packet_size = cpu_to_be32(pd->settings.size >> 2);
  
  	cgc.buflen = cgc.cmd[8] = size;

  	ret = pkt_mode_select(pd, &cgc);
  	if (ret) {

  		pkt_dump_sense(pd, &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;

  	pkt_err(pd, "bad state %d-%d-%d
  ", 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:

  			pkt_dbg(2, pd, "Wrong disc profile (%x)
  ",

  				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) {

  		pkt_notice(pd, "unknown disc - no track?
  ");

  		return 0;

  	}
  
  	if (di->disc_type != 0x20 && di->disc_type != 0) {

  		pkt_err(pd, "wrong disc type (%x)
  ", di->disc_type);

  		return 0;

  	}
  
  	if (di->erasable == 0) {

  		pkt_notice(pd, "disc not erasable
  ");

  		return 0;

  	}
  
  	if (di->border_status == PACKET_SESSION_RESERVED) {

  		pkt_err(pd, "can't write to last track (reserved)
  ");

  		return 0;

  	}

  	return 1;

  }

  static noinline_for_stack int pkt_probe_settings(struct pktcdvd_device *pd)

  {
  	struct packet_command cgc;
  	unsigned char buf[12];
  	disc_information di;
  	track_information ti;
  	int ret, track;
  
  	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
  	cgc.cmd[0] = GPCMD_GET_CONFIGURATION;
  	cgc.cmd[8] = 8;
  	ret = pkt_generic_packet(pd, &cgc);
  	pd->mmc3_profile = ret ? 0xffff : buf[6] << 8 | buf[7];
  
  	memset(&di, 0, sizeof(disc_information));
  	memset(&ti, 0, sizeof(track_information));

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

  		pkt_err(pd, "failed get_disc
  ");

  		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; */

  	ret = pkt_get_track_info(pd, track, 1, &ti);
  	if (ret) {

  		pkt_err(pd, "failed get_track
  ");

  		return ret;
  	}

  	if (!pkt_writable_track(pd, &ti)) {

  		pkt_err(pd, "can't write to this track
  ");

  		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) {

  		pkt_notice(pd, "detected zero packet size!
  ");

  		return -ENXIO;

  	}

  	if (pd->settings.size > PACKET_MAX_SECTORS) {

  		pkt_err(pd, "packet size is too big
  ");

  		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:

  			pkt_err(pd, "unknown data mode
  ");

  			return -EROFS;

  	}
  	return 0;
  }
  
  /*
   * enable/disable write caching on drive
   */

  static noinline_for_stack int pkt_write_caching(struct pktcdvd_device *pd,
  						int set)

  {
  	struct packet_command cgc;

  	struct scsi_sense_hdr sshdr;

  	unsigned char buf[64];
  	int ret;

  	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);

  	cgc.sshdr = &sshdr;

  	cgc.buflen = pd->mode_offset + 12;
  
  	/*
  	 * caching mode page might not be there, so quiet this command
  	 */
  	cgc.quiet = 1;

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

  		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) {

  		pkt_err(pd, "write caching control failed
  ");

  		pkt_dump_sense(pd, &cgc);

  	} else if (!ret && set)

  		pkt_notice(pd, "enabled write caching
  ");

  	return ret;
  }
  
  static int pkt_lock_door(struct pktcdvd_device *pd, int lockflag)
  {
  	struct packet_command cgc;
  
  	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
  	cgc.cmd[0] = GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL;
  	cgc.cmd[4] = lockflag ? 1 : 0;
  	return pkt_generic_packet(pd, &cgc);
  }
  
  /*
   * Returns drive maximum write speed
   */

  static noinline_for_stack int pkt_get_max_speed(struct pktcdvd_device *pd,
  						unsigned *write_speed)

  {
  	struct packet_command cgc;

  	struct scsi_sense_hdr sshdr;

  	unsigned char buf[256+18];
  	unsigned char *cap_buf;
  	int ret, offset;

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

  	cgc.sshdr = &sshdr;

  
  	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(pd, &cgc);

  			return ret;
  		}
  	}
  
  	offset = 20;			    /* Obsoleted field, used by older drives */
  	if (cap_buf[1] >= 28)
  		offset = 28;		    /* Current write speed selected */
  	if (cap_buf[1] >= 30) {
  		/* If the drive reports at least one "Logical Unit Write
  		 * Speed Performance Descriptor Block", use the information
  		 * in the first block. (contains the highest speed)
  		 */
  		int num_spdb = (cap_buf[30] << 8) + cap_buf[31];
  		if (num_spdb > 0)
  			offset = 34;
  	}
  
  	*write_speed = (cap_buf[offset] << 8) | cap_buf[offset + 1];
  	return 0;
  }
  
  /* These tables from cdrecord - I don't have orange book */
  /* standard speed CD-RW (1-4x) */
  static char clv_to_speed[16] = {
  	/* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
  	   0, 2, 4, 6, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
  /* high speed CD-RW (-10x) */
  static char hs_clv_to_speed[16] = {
  	/* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
  	   0, 2, 4, 6, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
  /* ultra high speed CD-RW */
  static char us_clv_to_speed[16] = {
  	/* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
  	   0, 2, 4, 8, 0, 0,16, 0,24,32,40,48, 0, 0, 0, 0
  };
  
  /*
   * reads the maximum media speed from ATIP
   */

  static noinline_for_stack int pkt_media_speed(struct pktcdvd_device *pd,
  						unsigned *speed)

  {
  	struct packet_command cgc;

  	struct scsi_sense_hdr sshdr;

  	unsigned char buf[64];
  	unsigned int size, st, sp;
  	int ret;
  
  	init_cdrom_command(&cgc, buf, 2, CGC_DATA_READ);

  	cgc.sshdr = &sshdr;

  	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(pd, &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.sshdr = &sshdr;

  	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(pd, &cgc);

  		return ret;
  	}

  	if (!(buf[6] & 0x40)) {

  		pkt_notice(pd, "disc type is not CD-RW
  ");

  		return 1;
  	}

  	if (!(buf[6] & 0x4)) {

  		pkt_notice(pd, "A1 values on media are not valid, maybe not CDRW?
  ");

  		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:

  			pkt_notice(pd, "unknown disc sub-type %d
  ", st);

  			return 1;
  	}
  	if (*speed) {

  		pkt_info(pd, "maximum media speed: %d
  ", *speed);

  		return 0;
  	} else {

  		pkt_notice(pd, "unknown speed %d for sub-type %d
  ", sp, st);

  		return 1;
  	}
  }

  static noinline_for_stack int pkt_perform_opc(struct pktcdvd_device *pd)

  {
  	struct packet_command cgc;

  	struct scsi_sense_hdr sshdr;

  	int ret;

  	pkt_dbg(2, pd, "Performing OPC
  ");

  
  	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);

  	cgc.sshdr = &sshdr;

  	cgc.timeout = 60*HZ;
  	cgc.cmd[0] = GPCMD_SEND_OPC;
  	cgc.cmd[1] = 1;

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

  		pkt_dump_sense(pd, &cgc);

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

  	ret = pkt_probe_settings(pd);
  	if (ret) {

  		pkt_dbg(2, pd, "failed probe
  ");

  		return ret;

  	}

  	ret = pkt_set_write_settings(pd);
  	if (ret) {

  		pkt_dbg(1, pd, "failed saving write settings
  ");

  		return -EIO;
  	}
  
  	pkt_write_caching(pd, USE_WCACHING);

  	ret = pkt_get_max_speed(pd, &write_speed);
  	if (ret)

  		write_speed = 16 * 177;
  	switch (pd->mmc3_profile) {
  		case 0x13: /* DVD-RW */
  		case 0x1a: /* DVD+RW */
  		case 0x12: /* DVD-RAM */

  			pkt_dbg(1, pd, "write speed %ukB/s
  ", write_speed);

  			break;
  		default:

  			ret = pkt_media_speed(pd, &media_write_speed);
  			if (ret)

  				media_write_speed = 16;
  			write_speed = min(write_speed, media_write_speed * 177);

  			pkt_dbg(1, pd, "write speed %ux
  ", write_speed / 176);

  			break;
  	}
  	read_speed = write_speed;

  	ret = pkt_set_speed(pd, write_speed, read_speed);
  	if (ret) {

  		pkt_dbg(1, pd, "couldn't set write speed
  ");

  		return -EIO;
  	}
  	pd->write_speed = write_speed;
  	pd->read_speed = read_speed;

  	ret = pkt_perform_opc(pd);
  	if (ret) {

  		pkt_dbg(1, pd, "Optimum Power Calibration failed
  ");

  	}
  
  	return 0;
  }
  
  /*
   * called at open time.
   */

  static int pkt_open_dev(struct pktcdvd_device *pd, fmode_t write)

  {
  	int ret;
  	long lba;

  	struct request_queue *q;

  	struct block_device *bdev;

  
  	/*
  	 * 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 open should not fail.

  	 */

  	bdev = blkdev_get_by_dev(pd->bdev->bd_dev, FMODE_READ | FMODE_EXCL, pd);
  	if (IS_ERR(bdev)) {
  		ret = PTR_ERR(bdev);

  		goto out;

  	}

  	ret = pkt_get_last_written(pd, &lba);
  	if (ret) {

  		pkt_err(pd, "pkt_get_last_written failed
  ");

  		goto out_putdev;

  	}
  
  	set_capacity(pd->disk, lba << 2);
  	set_capacity(pd->bdev->bd_disk, lba << 2);

  	bd_set_nr_sectors(pd->bdev, lba << 2);

  
  	q = bdev_get_queue(pd->bdev);
  	if (write) {

  		ret = pkt_open_write(pd);
  		if (ret)

  			goto out_putdev;

  		/*
  		 * Some CDRW drives can not handle writes larger than one packet,
  		 * even if the size is a multiple of the packet size.
  		 */

  		blk_queue_max_hw_sectors(q, pd->settings.size);

  		set_bit(PACKET_WRITABLE, &pd->flags);
  	} else {
  		pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
  		clear_bit(PACKET_WRITABLE, &pd->flags);
  	}

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

  		goto out_putdev;

  	if (write) {
  		if (!pkt_grow_pktlist(pd, CONFIG_CDROM_PKTCDVD_BUFFERS)) {

  			pkt_err(pd, "not enough memory for buffers
  ");

  			ret = -ENOMEM;

  			goto out_putdev;

  		}

  		pkt_info(pd, "%lukB available on disc
  ", lba << 1);

  	}

  
  	return 0;
  
  out_putdev:

  	blkdev_put(bdev, FMODE_READ | FMODE_EXCL);

  out:
  	return ret;
  }
  
  /*
   * called when the device is closed. makes sure that the device flushes
   * the internal cache before we close.
   */
  static void pkt_release_dev(struct pktcdvd_device *pd, int flush)
  {
  	if (flush && pkt_flush_cache(pd))

  		pkt_dbg(1, pd, "not flushing cache
  ");

  
  	pkt_lock_door(pd, 0);
  
  	pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);

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

  
  	pkt_shrink_pktlist(pd);

  }

  static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor)

  {
  	if (dev_minor >= MAX_WRITERS)
  		return NULL;

  
  	dev_minor = array_index_nospec(dev_minor, MAX_WRITERS);

  	return pkt_devs[dev_minor];
  }

  static int pkt_open(struct block_device *bdev, fmode_t mode)

  {
  	struct pktcdvd_device *pd = NULL;
  	int ret;

  	mutex_lock(&pktcdvd_mutex);

  	mutex_lock(&ctl_mutex);

  	pd = pkt_find_dev_from_minor(MINOR(bdev->bd_dev));

  	if (!pd) {
  		ret = -ENODEV;
  		goto out;
  	}
  	BUG_ON(pd->refcnt < 0);
  
  	pd->refcnt++;

  	if (pd->refcnt > 1) {

  		if ((mode & FMODE_WRITE) &&

  		    !test_bit(PACKET_WRITABLE, &pd->flags)) {
  			ret = -EBUSY;
  			goto out_dec;
  		}
  	} else {

  		ret = pkt_open_dev(pd, mode & FMODE_WRITE);

  		if (ret)

  			goto out_dec;

  		/*
  		 * needed here as well, since ext2 (among others) may change
  		 * the blocksize at mount time
  		 */

  		set_blocksize(bdev, CD_FRAMESIZE);

  	}

  	mutex_unlock(&ctl_mutex);

  	mutex_unlock(&pktcdvd_mutex);

  	return 0;
  
  out_dec:
  	pd->refcnt--;
  out:

  	mutex_unlock(&ctl_mutex);

  	mutex_unlock(&pktcdvd_mutex);

  	return ret;
  }

  static void pkt_close(struct gendisk *disk, fmode_t mode)

  {

  	struct pktcdvd_device *pd = disk->private_data;

  	mutex_lock(&pktcdvd_mutex);

  	mutex_lock(&ctl_mutex);

  	pd->refcnt--;
  	BUG_ON(pd->refcnt < 0);
  	if (pd->refcnt == 0) {
  		int flush = test_bit(PACKET_WRITABLE, &pd->flags);
  		pkt_release_dev(pd, flush);
  	}

  	mutex_unlock(&ctl_mutex);