text: /*
   * 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);
  