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genhd.c

/*
 *  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\n", 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\n",
                         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\n",
                   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\n",
                        sgp->driverfs_dev->driver->name);
            else
                  printk(" (driver?)\n");

            /* 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\n",
                        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\n\n");

      /* 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\n",
            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\n",
                  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\n",
                  __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\n", disk->minors);
}
static ssize_t disk_removable_read(struct gendisk * disk, char *page)
{
      return sprintf(page, "%d\n",
                   (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));

}
static ssize_t disk_size_read(struct gendisk * disk, char *page)
{
      return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk));
}
static ssize_t disk_capability_read(struct gendisk *disk, char *page)
{
      return sprintf(page, "%x\n", 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"
            "\n",
            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\n", 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,
                  struct kobj_uevent_env *env)
{
      struct kobj_type *ktype = get_ktype(kobj);
      struct device *physdev;
      struct gendisk *disk;
      struct hd_struct *part;

      if (ktype == &ktype_block) {
            disk = container_of(kobj, struct gendisk, kobj);
            add_uevent_var(env, "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(env, "MINOR=%u",
                         disk->first_minor + part->partno);
      } else
            return 0;

      add_uevent_var(env, "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(env, "PHYSDEVPATH=%s", path);
            kfree(path);

            if (physdev->bus)
                  add_uevent_var(env, "PHYSDEVBUS=%s", physdev->bus->name);

            if (physdev->driver)
                  add_uevent_var(env, physdev->driver->name);
      }

      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"
                        "\n\n");
      */
 
      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\n",
            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\n",
                        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) {
                        free_disk_stats(disk);
                        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);

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