/*
   *  gendisk handling
   */

  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/genhd.h>

  #include <linux/kdev_t.h>

  #include <linux/kernel.h>
  #include <linux/blkdev.h>
  #include <linux/init.h>
  #include <linux/spinlock.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
  #include <linux/kmod.h>
  #include <linux/kobj_map.h>

  #include <linux/buffer_head.h>

  #include <linux/mutex.h>

  struct kset block_subsys;

  static DEFINE_MUTEX(block_subsys_lock);

  
  /*
   * Can be deleted altogether. Later.
   *
   */
  static struct blk_major_name {
  	struct blk_major_name *next;
  	int major;
  	char name[16];

  } *major_names[BLKDEV_MAJOR_HASH_SIZE];

  
  /* index in the above - for now: assume no multimajor ranges */
  static inline int major_to_index(int major)
  {

  	return major % BLKDEV_MAJOR_HASH_SIZE;

  }

  #ifdef CONFIG_PROC_FS

  void blkdev_show(struct seq_file *f, off_t offset)

  {

  	struct blk_major_name *dp;

  	if (offset < BLKDEV_MAJOR_HASH_SIZE) {
  		mutex_lock(&block_subsys_lock);
  		for (dp = major_names[offset]; dp; dp = dp->next)
  			seq_printf(f, "%3d %s
  ", dp->major, dp->name);
  		mutex_unlock(&block_subsys_lock);

  	}

  }

  #endif /* CONFIG_PROC_FS */

  
  int register_blkdev(unsigned int major, const char *name)
  {
  	struct blk_major_name **n, *p;
  	int index, ret = 0;

  	mutex_lock(&block_subsys_lock);

  
  	/* temporary */
  	if (major == 0) {
  		for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
  			if (major_names[index] == NULL)
  				break;
  		}
  
  		if (index == 0) {
  			printk("register_blkdev: failed to get major for %s
  ",
  			       name);
  			ret = -EBUSY;
  			goto out;
  		}
  		major = index;
  		ret = major;
  	}
  
  	p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
  	if (p == NULL) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	p->major = major;
  	strlcpy(p->name, name, sizeof(p->name));
  	p->next = NULL;
  	index = major_to_index(major);
  
  	for (n = &major_names[index]; *n; n = &(*n)->next) {
  		if ((*n)->major == major)
  			break;
  	}
  	if (!*n)
  		*n = p;
  	else
  		ret = -EBUSY;
  
  	if (ret < 0) {
  		printk("register_blkdev: cannot get major %d for %s
  ",
  		       major, name);
  		kfree(p);
  	}
  out:

  	mutex_unlock(&block_subsys_lock);

  	return ret;
  }
  
  EXPORT_SYMBOL(register_blkdev);

  void unregister_blkdev(unsigned int major, const char *name)

  {
  	struct blk_major_name **n;
  	struct blk_major_name *p = NULL;
  	int index = major_to_index(major);

  	mutex_lock(&block_subsys_lock);

  	for (n = &major_names[index]; *n; n = &(*n)->next)
  		if ((*n)->major == major)
  			break;

  	if (!*n || strcmp((*n)->name, name)) {
  		WARN_ON(1);

  	} else {

  		p = *n;
  		*n = p->next;
  	}

  	mutex_unlock(&block_subsys_lock);

  	kfree(p);

  }
  
  EXPORT_SYMBOL(unregister_blkdev);
  
  static struct kobj_map *bdev_map;
  
  /*
   * Register device numbers dev..(dev+range-1)
   * range must be nonzero
   * The hash chain is sorted on range, so that subranges can override.
   */
  void blk_register_region(dev_t dev, unsigned long range, struct module *module,
  			 struct kobject *(*probe)(dev_t, int *, void *),
  			 int (*lock)(dev_t, void *), void *data)
  {
  	kobj_map(bdev_map, dev, range, module, probe, lock, data);
  }
  
  EXPORT_SYMBOL(blk_register_region);
  
  void blk_unregister_region(dev_t dev, unsigned long range)
  {
  	kobj_unmap(bdev_map, dev, range);
  }
  
  EXPORT_SYMBOL(blk_unregister_region);
  
  static struct kobject *exact_match(dev_t dev, int *part, void *data)
  {
  	struct gendisk *p = data;
  	return &p->kobj;
  }
  
  static int exact_lock(dev_t dev, void *data)
  {
  	struct gendisk *p = data;
  
  	if (!get_disk(p))
  		return -1;
  	return 0;
  }
  
  /**
   * add_disk - add partitioning information to kernel list
   * @disk: per-device partitioning information
   *
   * This function registers the partitioning information in @disk
   * with the kernel.
   */
  void add_disk(struct gendisk *disk)
  {
  	disk->flags |= GENHD_FL_UP;
  	blk_register_region(MKDEV(disk->major, disk->first_minor),
  			    disk->minors, NULL, exact_match, exact_lock, disk);
  	register_disk(disk);
  	blk_register_queue(disk);
  }
  
  EXPORT_SYMBOL(add_disk);
  EXPORT_SYMBOL(del_gendisk);	/* in partitions/check.c */
  
  void unlink_gendisk(struct gendisk *disk)
  {
  	blk_unregister_queue(disk);
  	blk_unregister_region(MKDEV(disk->major, disk->first_minor),
  			      disk->minors);
  }
  
  #define to_disk(obj) container_of(obj,struct gendisk,kobj)
  
  /**
   * get_gendisk - get partitioning information for a given device
   * @dev: device to get partitioning information for
   *
   * This function gets the structure containing partitioning
   * information for the given device @dev.
   */
  struct gendisk *get_gendisk(dev_t dev, int *part)
  {
  	struct kobject *kobj = kobj_lookup(bdev_map, dev, part);
  	return  kobj ? to_disk(kobj) : NULL;
  }

  /*
   * print a full list of all partitions - intended for places where the root
   * filesystem can't be mounted and thus to give the victim some idea of what
   * went wrong
   */
  void __init printk_all_partitions(void)
  {
  	int n;
  	struct gendisk *sgp;
  
  	mutex_lock(&block_subsys_lock);
  	/* For each block device... */
  	list_for_each_entry(sgp, &block_subsys.list, kobj.entry) {
  		char buf[BDEVNAME_SIZE];
  		/*
  		 * Don't show empty devices or things that have been surpressed
  		 */
  		if (get_capacity(sgp) == 0 ||
  		    (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
  			continue;
  
  		/*
  		 * Note, unlike /proc/partitions, I am showing the numbers in
  		 * hex - the same format as the root= option takes.
  		 */
  		printk("%02x%02x %10llu %s",
  			sgp->major, sgp->first_minor,
  			(unsigned long long)get_capacity(sgp) >> 1,
  			disk_name(sgp, 0, buf));
  		if (sgp->driverfs_dev != NULL &&
  		    sgp->driverfs_dev->driver != NULL)
  			printk(" driver: %s
  ",
  				sgp->driverfs_dev->driver->name);
  		else
  			printk(" (driver?)
  ");
  
  		/* now show the partitions */
  		for (n = 0; n < sgp->minors - 1; ++n) {
  			if (sgp->part[n] == NULL)
  				continue;
  			if (sgp->part[n]->nr_sects == 0)
  				continue;
  			printk("  %02x%02x %10llu %s
  ",
  				sgp->major, n + 1 + sgp->first_minor,
  				(unsigned long long)sgp->part[n]->nr_sects >> 1,
  				disk_name(sgp, n + 1, buf));
  		} /* partition subloop */
  	} /* Block device loop */
  
  	mutex_unlock(&block_subsys_lock);
  	return;
  }

  #ifdef CONFIG_PROC_FS
  /* iterator */
  static void *part_start(struct seq_file *part, loff_t *pos)
  {
  	struct list_head *p;
  	loff_t l = *pos;

  	mutex_lock(&block_subsys_lock);

  	list_for_each(p, &block_subsys.list)

  		if (!l--)
  			return list_entry(p, struct gendisk, kobj.entry);
  	return NULL;
  }
  
  static void *part_next(struct seq_file *part, void *v, loff_t *pos)
  {
  	struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
  	++*pos;

  	return p==&block_subsys.list ? NULL :

  		list_entry(p, struct gendisk, kobj.entry);
  }
  
  static void part_stop(struct seq_file *part, void *v)
  {

  	mutex_unlock(&block_subsys_lock);

  }
  
  static int show_partition(struct seq_file *part, void *v)
  {
  	struct gendisk *sgp = v;
  	int n;
  	char buf[BDEVNAME_SIZE];

  	if (&sgp->kobj.entry == block_subsys.list.next)

  		seq_puts(part, "major minor  #blocks  name
  
  ");
  
  	/* Don't show non-partitionable removeable devices or empty devices */
  	if (!get_capacity(sgp) ||
  			(sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
  		return 0;
  	if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
  		return 0;
  
  	/* show the full disk and all non-0 size partitions of it */
  	seq_printf(part, "%4d  %4d %10llu %s
  ",
  		sgp->major, sgp->first_minor,
  		(unsigned long long)get_capacity(sgp) >> 1,
  		disk_name(sgp, 0, buf));
  	for (n = 0; n < sgp->minors - 1; n++) {
  		if (!sgp->part[n])
  			continue;
  		if (sgp->part[n]->nr_sects == 0)
  			continue;
  		seq_printf(part, "%4d  %4d %10llu %s
  ",
  			sgp->major, n + 1 + sgp->first_minor,
  			(unsigned long long)sgp->part[n]->nr_sects >> 1 ,
  			disk_name(sgp, n + 1, buf));
  	}
  
  	return 0;
  }
  
  struct seq_operations partitions_op = {
  	.start =part_start,
  	.next =	part_next,
  	.stop =	part_stop,
  	.show =	show_partition
  };
  #endif
  
  
  extern int blk_dev_init(void);
  
  static struct kobject *base_probe(dev_t dev, int *part, void *data)
  {
  	if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
  		/* Make old-style 2.4 aliases work */
  		request_module("block-major-%d", MAJOR(dev));
  	return NULL;
  }
  
  static int __init genhd_device_init(void)
  {

  	int err;

  	bdev_map = kobj_map_init(base_probe, &block_subsys_lock);

  	blk_dev_init();

  	err = subsystem_register(&block_subsys);
  	if (err < 0)
  		printk(KERN_WARNING "%s: subsystem_register error: %d
  ",
  			__FUNCTION__, err);
  	return err;

  }
  
  subsys_initcall(genhd_device_init);
  
  
  
  /*
   * kobject & sysfs bindings for block devices
   */
  static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
  			      char *page)
  {
  	struct gendisk *disk = to_disk(kobj);
  	struct disk_attribute *disk_attr =
  		container_of(attr,struct disk_attribute,attr);

  	ssize_t ret = -EIO;

  
  	if (disk_attr->show)
  		ret = disk_attr->show(disk,page);
  	return ret;
  }

  static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
  			       const char *page, size_t count)
  {
  	struct gendisk *disk = to_disk(kobj);
  	struct disk_attribute *disk_attr =
  		container_of(attr,struct disk_attribute,attr);
  	ssize_t ret = 0;
  
  	if (disk_attr->store)
  		ret = disk_attr->store(disk, page, count);
  	return ret;
  }

  static struct sysfs_ops disk_sysfs_ops = {
  	.show	= &disk_attr_show,

  	.store	= &disk_attr_store,

  };

  static ssize_t disk_uevent_store(struct gendisk * disk,
  				 const char *buf, size_t count)
  {

  	kobject_uevent(&disk->kobj, KOBJ_ADD);

  	return count;
  }

  static ssize_t disk_dev_read(struct gendisk * disk, char *page)
  {
  	dev_t base = MKDEV(disk->major, disk->first_minor); 
  	return print_dev_t(page, base);
  }
  static ssize_t disk_range_read(struct gendisk * disk, char *page)
  {
  	return sprintf(page, "%d
  ", disk->minors);
  }
  static ssize_t disk_removable_read(struct gendisk * disk, char *page)
  {
  	return sprintf(page, "%d
  ",
  		       (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
  
  }
  static ssize_t disk_size_read(struct gendisk * disk, char *page)
  {
  	return sprintf(page, "%llu
  ", (unsigned long long)get_capacity(disk));
  }

  static ssize_t disk_capability_read(struct gendisk *disk, char *page)
  {
  	return sprintf(page, "%x
  ", disk->flags);
  }

  static ssize_t disk_stats_read(struct gendisk * disk, char *page)
  {
  	preempt_disable();
  	disk_round_stats(disk);
  	preempt_enable();
  	return sprintf(page,

  		"%8lu %8lu %8llu %8u "
  		"%8lu %8lu %8llu %8u "

  		"%8u %8u %8u"
  		"
  ",

  		disk_stat_read(disk, ios[READ]),
  		disk_stat_read(disk, merges[READ]),
  		(unsigned long long)disk_stat_read(disk, sectors[READ]),
  		jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
  		disk_stat_read(disk, ios[WRITE]),
  		disk_stat_read(disk, merges[WRITE]),
  		(unsigned long long)disk_stat_read(disk, sectors[WRITE]),
  		jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),

  		disk->in_flight,
  		jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
  		jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
  }

  static struct disk_attribute disk_attr_uevent = {
  	.attr = {.name = "uevent", .mode = S_IWUSR },
  	.store	= disk_uevent_store
  };

  static struct disk_attribute disk_attr_dev = {
  	.attr = {.name = "dev", .mode = S_IRUGO },
  	.show	= disk_dev_read
  };
  static struct disk_attribute disk_attr_range = {
  	.attr = {.name = "range", .mode = S_IRUGO },
  	.show	= disk_range_read
  };
  static struct disk_attribute disk_attr_removable = {
  	.attr = {.name = "removable", .mode = S_IRUGO },
  	.show	= disk_removable_read
  };
  static struct disk_attribute disk_attr_size = {
  	.attr = {.name = "size", .mode = S_IRUGO },
  	.show	= disk_size_read
  };

  static struct disk_attribute disk_attr_capability = {
  	.attr = {.name = "capability", .mode = S_IRUGO },
  	.show	= disk_capability_read
  };

  static struct disk_attribute disk_attr_stat = {
  	.attr = {.name = "stat", .mode = S_IRUGO },
  	.show	= disk_stats_read
  };

  #ifdef CONFIG_FAIL_MAKE_REQUEST
  
  static ssize_t disk_fail_store(struct gendisk * disk,
  			       const char *buf, size_t count)
  {
  	int i;
  
  	if (count > 0 && sscanf(buf, "%d", &i) > 0) {
  		if (i == 0)
  			disk->flags &= ~GENHD_FL_FAIL;
  		else
  			disk->flags |= GENHD_FL_FAIL;
  	}
  
  	return count;
  }
  static ssize_t disk_fail_read(struct gendisk * disk, char *page)
  {
  	return sprintf(page, "%d
  ", disk->flags & GENHD_FL_FAIL ? 1 : 0);
  }
  static struct disk_attribute disk_attr_fail = {
  	.attr = {.name = "make-it-fail", .mode = S_IRUGO | S_IWUSR },
  	.store	= disk_fail_store,
  	.show	= disk_fail_read
  };
  
  #endif

  static struct attribute * default_attrs[] = {

  	&disk_attr_uevent.attr,

  	&disk_attr_dev.attr,
  	&disk_attr_range.attr,
  	&disk_attr_removable.attr,
  	&disk_attr_size.attr,
  	&disk_attr_stat.attr,

  	&disk_attr_capability.attr,

  #ifdef CONFIG_FAIL_MAKE_REQUEST
  	&disk_attr_fail.attr,
  #endif

  	NULL,
  };
  
  static void disk_release(struct kobject * kobj)
  {
  	struct gendisk *disk = to_disk(kobj);
  	kfree(disk->random);
  	kfree(disk->part);
  	free_disk_stats(disk);
  	kfree(disk);
  }
  
  static struct kobj_type ktype_block = {
  	.release	= disk_release,
  	.sysfs_ops	= &disk_sysfs_ops,
  	.default_attrs	= default_attrs,
  };
  
  extern struct kobj_type ktype_part;

  static int block_uevent_filter(struct kset *kset, struct kobject *kobj)

  {
  	struct kobj_type *ktype = get_ktype(kobj);
  
  	return ((ktype == &ktype_block) || (ktype == &ktype_part));
  }

  static int block_uevent(struct kset *kset, struct kobject *kobj, char **envp,

  			 int num_envp, char *buffer, int buffer_size)
  {
  	struct kobj_type *ktype = get_ktype(kobj);
  	struct device *physdev;
  	struct gendisk *disk;
  	struct hd_struct *part;
  	int length = 0;
  	int i = 0;
  
  	if (ktype == &ktype_block) {
  		disk = container_of(kobj, struct gendisk, kobj);

  		add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
  			       &length, "MINOR=%u", disk->first_minor);

  	} else if (ktype == &ktype_part) {
  		disk = container_of(kobj->parent, struct gendisk, kobj);
  		part = container_of(kobj, struct hd_struct, kobj);

  		add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
  			       &length, "MINOR=%u",
  			       disk->first_minor + part->partno);

  	} else
  		return 0;

  	add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
  		       "MAJOR=%u", disk->major);

  
  	/* add physical device, backing this device  */
  	physdev = disk->driverfs_dev;
  	if (physdev) {
  		char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL);

  		add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
  			       &length, "PHYSDEVPATH=%s", path);

  		kfree(path);
  
  		if (physdev->bus)

  			add_uevent_var(envp, num_envp, &i,
  				       buffer, buffer_size, &length,
  				       "PHYSDEVBUS=%s",
  				       physdev->bus->name);

  
  		if (physdev->driver)

  			add_uevent_var(envp, num_envp, &i,
  				       buffer, buffer_size, &length,
  				       "PHYSDEVDRIVER=%s",
  				       physdev->driver->name);

  	}
  
  	/* terminate, set to next free slot, shrink available space */
  	envp[i] = NULL;
  	envp = &envp[i];
  	num_envp -= i;
  	buffer = &buffer[length];
  	buffer_size -= length;
  
  	return 0;
  }

  static struct kset_uevent_ops block_uevent_ops = {
  	.filter		= block_uevent_filter,
  	.uevent		= block_uevent,

  };

  decl_subsys(block, &ktype_block, &block_uevent_ops);

  
  /*
   * aggregate disk stat collector.  Uses the same stats that the sysfs
   * entries do, above, but makes them available through one seq_file.
   * Watching a few disks may be efficient through sysfs, but watching
   * all of them will be more efficient through this interface.
   *
   * The output looks suspiciously like /proc/partitions with a bunch of
   * extra fields.
   */
  
  /* iterator */
  static void *diskstats_start(struct seq_file *part, loff_t *pos)
  {
  	loff_t k = *pos;
  	struct list_head *p;

  	mutex_lock(&block_subsys_lock);

  	list_for_each(p, &block_subsys.list)

  		if (!k--)
  			return list_entry(p, struct gendisk, kobj.entry);
  	return NULL;
  }
  
  static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
  {
  	struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
  	++*pos;

  	return p==&block_subsys.list ? NULL :

  		list_entry(p, struct gendisk, kobj.entry);
  }
  
  static void diskstats_stop(struct seq_file *part, void *v)
  {

  	mutex_unlock(&block_subsys_lock);

  }
  
  static int diskstats_show(struct seq_file *s, void *v)
  {
  	struct gendisk *gp = v;
  	char buf[BDEVNAME_SIZE];
  	int n = 0;
  
  	/*
  	if (&sgp->kobj.entry == block_subsys.kset.list.next)
  		seq_puts(s,	"major minor name"
  				"     rio rmerge rsect ruse wio wmerge "
  				"wsect wuse running use aveq"
  				"
  
  ");
  	*/
   
  	preempt_disable();
  	disk_round_stats(gp);
  	preempt_enable();

  	seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u
  ",

  		gp->major, n + gp->first_minor, disk_name(gp, n, buf),

  		disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
  		(unsigned long long)disk_stat_read(gp, sectors[0]),
  		jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
  		disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
  		(unsigned long long)disk_stat_read(gp, sectors[1]),
  		jiffies_to_msecs(disk_stat_read(gp, ticks[1])),

  		gp->in_flight,
  		jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
  		jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
  
  	/* now show all non-0 size partitions of it */
  	for (n = 0; n < gp->minors - 1; n++) {
  		struct hd_struct *hd = gp->part[n];
  
  		if (hd && hd->nr_sects)
  			seq_printf(s, "%4d %4d %s %u %u %u %u
  ",
  				gp->major, n + gp->first_minor + 1,
  				disk_name(gp, n + 1, buf),

  				hd->ios[0], hd->sectors[0],
  				hd->ios[1], hd->sectors[1]);

  	}
   
  	return 0;
  }
  
  struct seq_operations diskstats_op = {
  	.start	= diskstats_start,
  	.next	= diskstats_next,
  	.stop	= diskstats_stop,
  	.show	= diskstats_show
  };

  static void media_change_notify_thread(struct work_struct *work)
  {
  	struct gendisk *gd = container_of(work, struct gendisk, async_notify);
  	char event[] = "MEDIA_CHANGE=1";
  	char *envp[] = { event, NULL };
  
  	/*
  	 * set enviroment vars to indicate which event this is for
  	 * so that user space will know to go check the media status.
  	 */
  	kobject_uevent_env(&gd->kobj, KOBJ_CHANGE, envp);
  	put_device(gd->driverfs_dev);
  }
  
  void genhd_media_change_notify(struct gendisk *disk)
  {
  	get_device(disk->driverfs_dev);
  	schedule_work(&disk->async_notify);
  }
  EXPORT_SYMBOL_GPL(genhd_media_change_notify);

  struct gendisk *alloc_disk(int minors)
  {

  	return alloc_disk_node(minors, -1);
  }
  
  struct gendisk *alloc_disk_node(int minors, int node_id)
  {
  	struct gendisk *disk;

  	disk = kmalloc_node(sizeof(struct gendisk),
  				GFP_KERNEL | __GFP_ZERO, node_id);

  	if (disk) {

  		if (!init_disk_stats(disk)) {
  			kfree(disk);
  			return NULL;
  		}
  		if (minors > 1) {
  			int size = (minors - 1) * sizeof(struct hd_struct *);

  			disk->part = kmalloc_node(size,
  				GFP_KERNEL | __GFP_ZERO, node_id);

  			if (!disk->part) {
  				kfree(disk);
  				return NULL;
  			}

  		}
  		disk->minors = minors;
  		kobj_set_kset_s(disk,block_subsys);
  		kobject_init(&disk->kobj);
  		rand_initialize_disk(disk);

  		INIT_WORK(&disk->async_notify,
  			media_change_notify_thread);

  	}
  	return disk;
  }
  
  EXPORT_SYMBOL(alloc_disk);

  EXPORT_SYMBOL(alloc_disk_node);

  
  struct kobject *get_disk(struct gendisk *disk)
  {
  	struct module *owner;
  	struct kobject *kobj;
  
  	if (!disk->fops)
  		return NULL;
  	owner = disk->fops->owner;
  	if (owner && !try_module_get(owner))
  		return NULL;
  	kobj = kobject_get(&disk->kobj);
  	if (kobj == NULL) {
  		module_put(owner);
  		return NULL;
  	}
  	return kobj;
  
  }
  
  EXPORT_SYMBOL(get_disk);
  
  void put_disk(struct gendisk *disk)
  {
  	if (disk)
  		kobject_put(&disk->kobj);
  }
  
  EXPORT_SYMBOL(put_disk);
  
  void set_device_ro(struct block_device *bdev, int flag)
  {
  	if (bdev->bd_contains != bdev)
  		bdev->bd_part->policy = flag;
  	else
  		bdev->bd_disk->policy = flag;
  }
  
  EXPORT_SYMBOL(set_device_ro);
  
  void set_disk_ro(struct gendisk *disk, int flag)
  {
  	int i;
  	disk->policy = flag;
  	for (i = 0; i < disk->minors - 1; i++)
  		if (disk->part[i]) disk->part[i]->policy = flag;
  }
  
  EXPORT_SYMBOL(set_disk_ro);
  
  int bdev_read_only(struct block_device *bdev)
  {
  	if (!bdev)
  		return 0;
  	else if (bdev->bd_contains != bdev)
  		return bdev->bd_part->policy;
  	else
  		return bdev->bd_disk->policy;
  }
  
  EXPORT_SYMBOL(bdev_read_only);
  
  int invalidate_partition(struct gendisk *disk, int index)
  {
  	int res = 0;
  	struct block_device *bdev = bdget_disk(disk, index);
  	if (bdev) {

  		fsync_bdev(bdev);
  		res = __invalidate_device(bdev);

  		bdput(bdev);
  	}
  	return res;
  }
  
  EXPORT_SYMBOL(invalidate_partition);