ClabureDB: Classified Bug-Reports Database

   /*
    *  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/proc_fs.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>
  #include <linux/idr.h>
  
  #include "blk.h"
  
  static DEFINE_MUTEX(block_class_lock);
  #ifndef CONFIG_SYSFS_DEPRECATED
  struct kobject *block_depr;
  #endif
  
  /* for extended dynamic devt allocation, currently only one major is used */
  #define MAX_EXT_DEVT                (1 << MINORBITS)
  
  /* For extended devt allocation.  ext_devt_mutex prevents look up
   * results from going away underneath its user.
   */
  static DEFINE_MUTEX(ext_devt_mutex);
  static DEFINE_IDR(ext_devt_idr);
  
  static struct device_type disk_type;
  
  /**
   * disk_get_part - get partition
   * @disk: disk to look partition from
   * @partno: partition number
   *
   * Look for partition @partno from @disk.  If found, increment
   * reference count and return it.
   *
   * CONTEXT:
   * Don't care.
   *
   * RETURNS:
   * Pointer to the found partition on success, NULL if not found.
   */
  struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
  {
          struct hd_struct *part = NULL;
          struct disk_part_tbl *ptbl;
  
          if (unlikely(partno < 0))
                  return NULL;
  
          rcu_read_lock();
  
          ptbl = rcu_dereference(disk->part_tbl);
          if (likely(partno < ptbl->len)) {
                  part = rcu_dereference(ptbl->part[partno]);
                  if (part)
                          get_device(part_to_dev(part));
          }
  
          rcu_read_unlock();
  
          return part;
  }
  EXPORT_SYMBOL_GPL(disk_get_part);
  
  /**
   * disk_part_iter_init - initialize partition iterator
   * @piter: iterator to initialize
   * @disk: disk to iterate over
   * @flags: DISK_PITER_* flags
   *
   * Initialize @piter so that it iterates over partitions of @disk.
   *
   * CONTEXT:
   * Don't care.
   */
  void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
                            unsigned int flags)
  {
          struct disk_part_tbl *ptbl;
  
          rcu_read_lock();
          ptbl = rcu_dereference(disk->part_tbl);
  
          piter->disk = disk;
          piter->part = NULL;
  
          if (flags & DISK_PITER_REVERSE)
                 piter->idx = ptbl->len - 1;
         else if (flags & DISK_PITER_INCL_PART0)
                 piter->idx = 0;
         else
                 piter->idx = 1;
 
         piter->flags = flags;
 
         rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(disk_part_iter_init);
 
 /**
  * disk_part_iter_next - proceed iterator to the next partition and return it
  * @piter: iterator of interest
  *
  * Proceed @piter to the next partition and return it.
  *
  * CONTEXT:
  * Don't care.
  */
 struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
 {
         struct disk_part_tbl *ptbl;
         int inc, end;
 
         /* put the last partition */
         disk_put_part(piter->part);
         piter->part = NULL;
 
         /* get part_tbl */
         rcu_read_lock();
         ptbl = rcu_dereference(piter->disk->part_tbl);
 
         /* determine iteration parameters */
         if (piter->flags & DISK_PITER_REVERSE) {
                 inc = -1;
                 if (piter->flags & DISK_PITER_INCL_PART0)
                         end = -1;
                 else
                         end = 0;
         } else {
                 inc = 1;
                 end = ptbl->len;
         }
 
         /* iterate to the next partition */
         for (; piter->idx != end; piter->idx += inc) {
                 struct hd_struct *part;
 
                 part = rcu_dereference(ptbl->part[piter->idx]);
                 if (!part)
                         continue;
                 if (!(piter->flags & DISK_PITER_INCL_EMPTY) && !part->nr_sects)
                         continue;
 
                 get_device(part_to_dev(part));
                 piter->part = part;
                 piter->idx += inc;
                 break;
         }
 
         rcu_read_unlock();
 
         return piter->part;
 }
 EXPORT_SYMBOL_GPL(disk_part_iter_next);
 
 /**
  * disk_part_iter_exit - finish up partition iteration
  * @piter: iter of interest
  *
  * Called when iteration is over.  Cleans up @piter.
  *
  * CONTEXT:
  * Don't care.
  */
 void disk_part_iter_exit(struct disk_part_iter *piter)
 {
         disk_put_part(piter->part);
         piter->part = NULL;
 }
 EXPORT_SYMBOL_GPL(disk_part_iter_exit);
 
 /**
  * disk_map_sector_rcu - map sector to partition
  * @disk: gendisk of interest
  * @sector: sector to map
  *
  * Find out which partition @sector maps to on @disk.  This is
  * primarily used for stats accounting.
  *
  * CONTEXT:
  * RCU read locked.  The returned partition pointer is valid only
  * while preemption is disabled.
  *
  * RETURNS:
  * Found partition on success, part0 is returned if no partition matches
  */
 struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
 {
         struct disk_part_tbl *ptbl;
         int i;
 
         ptbl = rcu_dereference(disk->part_tbl);
 
         for (i = 1; i < ptbl->len; i++) {
                 struct hd_struct *part = rcu_dereference(ptbl->part[i]);
 
                 if (part && part->start_sect <= sector &&
                     sector < part->start_sect + part->nr_sects)
                         return part;
         }
         return &disk->part0;
 }
 EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
 
 /*
  * 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 *seqf, off_t offset)
 {
         struct blk_major_name *dp;
 
         if (offset < BLKDEV_MAJOR_HASH_SIZE) {
                 mutex_lock(&block_class_lock);
                 for (dp = major_names[offset]; dp; dp = dp->next)
                         seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
                 mutex_unlock(&block_class_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_class_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_class_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_class_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_class_lock);
         kfree(p);
 }
 
 EXPORT_SYMBOL(unregister_blkdev);
 
 static struct kobj_map *bdev_map;
 
 /**
  * blk_mangle_minor - scatter minor numbers apart
  * @minor: minor number to mangle
  *
  * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
  * is enabled.  Mangling twice gives the original value.
  *
  * RETURNS:
  * Mangled value.
  *
  * CONTEXT:
  * Don't care.
  */
 static int blk_mangle_minor(int minor)
 {
 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
         int i;
 
         for (i = 0; i < MINORBITS / 2; i++) {
                 int low = minor & (1 << i);
                 int high = minor & (1 << (MINORBITS - 1 - i));
                 int distance = MINORBITS - 1 - 2 * i;
 
                 minor ^= low | high;        /* clear both bits */
                 low <<= distance;        /* swap the positions */
                 high >>= distance;
                 minor |= low | high;        /* and set */
         }
 #endif
         return minor;
 }
 
 /**
  * blk_alloc_devt - allocate a dev_t for a partition
  * @part: partition to allocate dev_t for
  * @devt: out parameter for resulting dev_t
  *
  * Allocate a dev_t for block device.
  *
  * RETURNS:
  * 0 on success, allocated dev_t is returned in *@devt.  -errno on
  * failure.
  *
  * CONTEXT:
  * Might sleep.
  */
 int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
 {
         struct gendisk *disk = part_to_disk(part);
         int idx, rc;
 
         /* in consecutive minor range? */
         if (part->partno < disk->minors) {
                 *devt = MKDEV(disk->major, disk->first_minor + part->partno);
                 return 0;
         }
 
         /* allocate ext devt */
         do {
                 if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
                         return -ENOMEM;
                 rc = idr_get_new(&ext_devt_idr, part, &idx);
         } while (rc == -EAGAIN);
 
         if (rc)
                 return rc;
 
         if (idx > MAX_EXT_DEVT) {
                 idr_remove(&ext_devt_idr, idx);
                 return -EBUSY;
         }
 
         *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
         return 0;
 }
 
 /**
  * blk_free_devt - free a dev_t
  * @devt: dev_t to free
  *
  * Free @devt which was allocated using blk_alloc_devt().
  *
  * CONTEXT:
  * Might sleep.
  */
 void blk_free_devt(dev_t devt)
 {
         might_sleep();
 
         if (devt == MKDEV(0, 0))
                 return;
 
         if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
                 mutex_lock(&ext_devt_mutex);
                 idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
                 mutex_unlock(&ext_devt_mutex);
         }
 }
 
 static char *bdevt_str(dev_t devt, char *buf)
 {
         if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
                 char tbuf[BDEVT_SIZE];
                 snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
                 snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
         } else
                 snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
 
         return buf;
 }
 
 /*
  * 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 devt, unsigned long range, struct module *module,
                          struct kobject *(*probe)(dev_t, int *, void *),
                          int (*lock)(dev_t, void *), void *data)
 {
         kobj_map(bdev_map, devt, range, module, probe, lock, data);
 }
 
 EXPORT_SYMBOL(blk_register_region);
 
 void blk_unregister_region(dev_t devt, unsigned long range)
 {
         kobj_unmap(bdev_map, devt, range);
 }
 
 EXPORT_SYMBOL(blk_unregister_region);
 
 static struct kobject *exact_match(dev_t devt, int *partno, void *data)
 {
         struct gendisk *p = data;
 
         return &disk_to_dev(p)->kobj;
 }
 
 static int exact_lock(dev_t devt, 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.
  *
  * FIXME: error handling
  */
 void add_disk(struct gendisk *disk)
 {
         struct backing_dev_info *bdi;
         dev_t devt;
         int retval;
 
         /* minors == 0 indicates to use ext devt from part0 and should
          * be accompanied with EXT_DEVT flag.  Make sure all
          * parameters make sense.
          */
         WARN_ON(disk->minors && !(disk->major || disk->first_minor));
         WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
 
         disk->flags |= GENHD_FL_UP;
 
         retval = blk_alloc_devt(&disk->part0, &devt);
         if (retval) {
                 WARN_ON(1);
                 return;
         }
         disk_to_dev(disk)->devt = devt;
 
         /* ->major and ->first_minor aren't supposed to be
          * dereferenced from here on, but set them just in case.
          */
         disk->major = MAJOR(devt);
         disk->first_minor = MINOR(devt);
 
         blk_register_region(disk_devt(disk), disk->minors, NULL,
                             exact_match, exact_lock, disk);
         register_disk(disk);
         blk_register_queue(disk);
 
         bdi = &disk->queue->backing_dev_info;
         bdi_register_dev(bdi, disk_devt(disk));
         retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
                                    "bdi");
         WARN_ON(retval);
 }
 
 EXPORT_SYMBOL(add_disk);
 EXPORT_SYMBOL(del_gendisk);        /* in partitions/check.c */
 
 void unlink_gendisk(struct gendisk *disk)
 {
         sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
         bdi_unregister(&disk->queue->backing_dev_info);
         blk_unregister_queue(disk);
         blk_unregister_region(disk_devt(disk), disk->minors);
 }
 
 /**
  * get_gendisk - get partitioning information for a given device
  * @devt: device to get partitioning information for
  * @partno: returned partition index
  *
  * This function gets the structure containing partitioning
  * information for the given device @devt.
  */
 struct gendisk *get_gendisk(dev_t devt, int *partno)
 {
         struct gendisk *disk = NULL;
 
         if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
                 struct kobject *kobj;
 
                 kobj = kobj_lookup(bdev_map, devt, partno);
                 if (kobj)
                         disk = dev_to_disk(kobj_to_dev(kobj));
         } else {
                 struct hd_struct *part;
 
                 mutex_lock(&ext_devt_mutex);
                 part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
                 if (part && get_disk(part_to_disk(part))) {
                         *partno = part->partno;
                         disk = part_to_disk(part);
                 }
                 mutex_unlock(&ext_devt_mutex);
         }
 
         return disk;
 }
 
 /**
  * bdget_disk - do bdget() by gendisk and partition number
  * @disk: gendisk of interest
  * @partno: partition number
  *
  * Find partition @partno from @disk, do bdget() on it.
  *
  * CONTEXT:
  * Don't care.
  *
  * RETURNS:
  * Resulting block_device on success, NULL on failure.
  */
 struct block_device *bdget_disk(struct gendisk *disk, int partno)
 {
         struct hd_struct *part;
         struct block_device *bdev = NULL;
 
         part = disk_get_part(disk, partno);
         if (part)
                 bdev = bdget(part_devt(part));
         disk_put_part(part);
 
         return bdev;
 }
 EXPORT_SYMBOL(bdget_disk);
 
 /*
  * 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)
 {
         struct class_dev_iter iter;
         struct device *dev;
 
         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
         while ((dev = class_dev_iter_next(&iter))) {
                 struct gendisk *disk = dev_to_disk(dev);
                 struct disk_part_iter piter;
                 struct hd_struct *part;
                 char name_buf[BDEVNAME_SIZE];
                 char devt_buf[BDEVT_SIZE];
 
                 /*
                  * Don't show empty devices or things that have been
                  * surpressed
                  */
                 if (get_capacity(disk) == 0 ||
                     (disk->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.
                  */
                 disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
                 while ((part = disk_part_iter_next(&piter))) {
                         bool is_part0 = part == &disk->part0;
 
                         printk("%s%s %10llu %s", is_part0 ? "" : "  ",
                                bdevt_str(part_devt(part), devt_buf),
                                (unsigned long long)part->nr_sects >> 1,
                                disk_name(disk, part->partno, name_buf));
                         if (is_part0) {
                                 if (disk->driverfs_dev != NULL &&
                                     disk->driverfs_dev->driver != NULL)
                                         printk(" driver: %s\n",
                                               disk->driverfs_dev->driver->name);
                                 else
                                         printk(" (driver?)\n");
                         } else
                                 printk("\n");
                 }
                 disk_part_iter_exit(&piter);
         }
         class_dev_iter_exit(&iter);
 }
 
 #ifdef CONFIG_PROC_FS
 /* iterator */
 static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
 {
         loff_t skip = *pos;
         struct class_dev_iter *iter;
         struct device *dev;
 
         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
         if (!iter)
                 return ERR_PTR(-ENOMEM);
 
         seqf->private = iter;
         class_dev_iter_init(iter, &block_class, NULL, &disk_type);
         do {
                 dev = class_dev_iter_next(iter);
                 if (!dev)
                         return NULL;
         } while (skip--);
 
         return dev_to_disk(dev);
 }
 
 static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
 {
         struct device *dev;
 
         (*pos)++;
         dev = class_dev_iter_next(seqf->private);
         if (dev)
                 return dev_to_disk(dev);
 
         return NULL;
 }
 
 static void disk_seqf_stop(struct seq_file *seqf, void *v)
 {
         struct class_dev_iter *iter = seqf->private;
 
         /* stop is called even after start failed :-( */
         if (iter) {
                 class_dev_iter_exit(iter);
                 kfree(iter);
         }
 }
 
 static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
 {
         static void *p;
 
         p = disk_seqf_start(seqf, pos);
         if (!IS_ERR(p) && p && !*pos)
                 seq_puts(seqf, "major minor  #blocks  name\n\n");
         return p;
 }
 
 static int show_partition(struct seq_file *seqf, void *v)
 {
         struct gendisk *sgp = v;
         struct disk_part_iter piter;
         struct hd_struct *part;
         char buf[BDEVNAME_SIZE];
 
         /* Don't show non-partitionable removeable devices or empty devices */
         if (!get_capacity(sgp) || (!disk_partitionable(sgp) &&
                                    (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 */
         disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
         while ((part = disk_part_iter_next(&piter)))
                 seq_printf(seqf, "%4d  %7d %10llu %s\n",
                            MAJOR(part_devt(part)), MINOR(part_devt(part)),
                            (unsigned long long)part->nr_sects >> 1,
                            disk_name(sgp, part->partno, buf));
         disk_part_iter_exit(&piter);
 
         return 0;
 }
 
 static const struct seq_operations partitions_op = {
         .start        = show_partition_start,
         .next        = disk_seqf_next,
         .stop        = disk_seqf_stop,
         .show        = show_partition
 };
 
 static int partitions_open(struct inode *inode, struct file *file)
 {
         return seq_open(file, &partitions_op);
 }
 
 static const struct file_operations proc_partitions_operations = {
         .open                = partitions_open,
         .read                = seq_read,
         .llseek                = seq_lseek,
         .release        = seq_release,
 };
 #endif
 
 
 static struct kobject *base_probe(dev_t devt, int *partno, void *data)
 {
         if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
                 /* Make old-style 2.4 aliases work */
                 request_module("block-major-%d", MAJOR(devt));
         return NULL;
 }
 
 static int __init genhd_device_init(void)
 {
         int error;
 
         block_class.dev_kobj = sysfs_dev_block_kobj;
         error = class_register(&block_class);
         if (unlikely(error))
                 return error;
         bdev_map = kobj_map_init(base_probe, &block_class_lock);
         blk_dev_init();
 
         register_blkdev(BLOCK_EXT_MAJOR, "blkext");
 
 #ifndef CONFIG_SYSFS_DEPRECATED
         /* create top-level block dir */
         block_depr = kobject_create_and_add("block", NULL);
 #endif
         return 0;
 }
 
 subsys_initcall(genhd_device_init);
 
 static ssize_t disk_range_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
         return sprintf(buf, "%d\n", disk->minors);
 }
 
 static ssize_t disk_ext_range_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
         return sprintf(buf, "%d\n", disk_max_parts(disk));
 }
 
 static ssize_t disk_removable_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
         return sprintf(buf, "%d\n",
                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 }
 
 static ssize_t disk_ro_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
         return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
 }
 
 static ssize_t disk_capability_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
         return sprintf(buf, "%x\n", disk->flags);
 }
 
 static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
 static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
 static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
 static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
 static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
 static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
 static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
 #ifdef CONFIG_FAIL_MAKE_REQUEST
 static struct device_attribute dev_attr_fail =
         __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
 #endif
 #ifdef CONFIG_FAIL_IO_TIMEOUT
 static struct device_attribute dev_attr_fail_timeout =
         __ATTR(io-timeout-fail,  S_IRUGO|S_IWUSR, part_timeout_show,
                 part_timeout_store);
 #endif
 
 static struct attribute *disk_attrs[] = {
         &dev_attr_range.attr,
         &dev_attr_ext_range.attr,
         &dev_attr_removable.attr,
         &dev_attr_ro.attr,
         &dev_attr_size.attr,
         &dev_attr_capability.attr,
         &dev_attr_stat.attr,
 #ifdef CONFIG_FAIL_MAKE_REQUEST
         &dev_attr_fail.attr,
 #endif
 #ifdef CONFIG_FAIL_IO_TIMEOUT
         &dev_attr_fail_timeout.attr,
 #endif
         NULL
 };
 
 static struct attribute_group disk_attr_group = {
         .attrs = disk_attrs,
 };
 
 static struct attribute_group *disk_attr_groups[] = {
         &disk_attr_group,
         NULL
 };
 
 static void disk_free_ptbl_rcu_cb(struct rcu_head *head)
 {
         struct disk_part_tbl *ptbl =
                 container_of(head, struct disk_part_tbl, rcu_head);
 
         kfree(ptbl);
 }
 
 /**
  * disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
  * @disk: disk to replace part_tbl for
  * @new_ptbl: new part_tbl to install
  *
  * Replace disk->part_tbl with @new_ptbl in RCU-safe way.  The
  * original ptbl is freed using RCU callback.
  *
  * LOCKING:
  * Matching bd_mutx locked.
  */
 static void disk_replace_part_tbl(struct gendisk *disk,
                                   struct disk_part_tbl *new_ptbl)
 {
         struct disk_part_tbl *old_ptbl = disk->part_tbl;
 
         rcu_assign_pointer(disk->part_tbl, new_ptbl);
         if (old_ptbl)
                 call_rcu(&old_ptbl->rcu_head, disk_free_ptbl_rcu_cb);
 }
 
 /**
  * disk_expand_part_tbl - expand disk->part_tbl
  * @disk: disk to expand part_tbl for
  * @partno: expand such that this partno can fit in
  *
  * Expand disk->part_tbl such that @partno can fit in.  disk->part_tbl
  * uses RCU to allow unlocked dereferencing for stats and other stuff.
  *
  * LOCKING:
  * Matching bd_mutex locked, might sleep.
  *
  * RETURNS:
  * 0 on success, -errno on failure.
  */
 int disk_expand_part_tbl(struct gendisk *disk, int partno)
 {
         struct disk_part_tbl *old_ptbl = disk->part_tbl;
         struct disk_part_tbl *new_ptbl;
         int len = old_ptbl ? old_ptbl->len : 0;
         int target = partno + 1;
         size_t size;
         int i;
 
         /* disk_max_parts() is zero during initialization, ignore if so */
         if (disk_max_parts(disk) && target > disk_max_parts(disk))
                 return -EINVAL;
 
         if (target <= len)
                 return 0;
 
         size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
         new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
         if (!new_ptbl)
                 return -ENOMEM;
 
         INIT_RCU_HEAD(&new_ptbl->rcu_head);
         new_ptbl->len = target;
 
         for (i = 0; i < len; i++)
                 rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
 
         disk_replace_part_tbl(disk, new_ptbl);
         return 0;
 }
 
 static void disk_release(struct device *dev)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
         kfree(disk->random);
         disk_replace_part_tbl(disk, NULL);
         free_part_stats(&disk->part0);
         kfree(disk);
 }
 struct class block_class = {
         .name                = "block",
 };
 
 static struct device_type disk_type = {
         .name                = "disk",
         .groups                = disk_attr_groups,
         .release        = disk_release,
 };
 
 #ifdef CONFIG_PROC_FS
 /*
  * aggregate disk stat collector.  Uses the same stats that the sysfs
  * entries do, above, but makes them available through one seq_file.
  *
  * The output looks suspiciously like /proc/partitions with a bunch of
  * extra fields.
  */
 static int diskstats_show(struct seq_file *seqf, void *v)
 {
         struct gendisk *gp = v;
         struct disk_part_iter piter;
         struct hd_struct *hd;
         char buf[BDEVNAME_SIZE];
         int cpu;
 
         /*
         if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
                 seq_puts(seqf,        "major minor name"
                                 "     rio rmerge rsect ruse wio wmerge "
                                 "wsect wuse running use aveq"
                                 "\n\n");
         */
  
         disk_part_iter_init(&piter, gp, DISK_PITER_INCL_PART0);
         while ((hd = disk_part_iter_next(&piter))) {
                 cpu = part_stat_lock();
                 part_round_stats(cpu, hd);
                 part_stat_unlock();
                 seq_printf(seqf, "%4d %7d %s %lu %lu %llu "
                            "%u %lu %lu %llu %u %u %u %u\n",
                            MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
                            disk_name(gp, hd->partno, buf),
                            part_stat_read(hd, ios[0]),
                            part_stat_read(hd, merges[0]),
                            (unsigned long long)part_stat_read(hd, sectors[0]),
                            jiffies_to_msecs(part_stat_read(hd, ticks[0])),
                            part_stat_read(hd, ios[1]),
                            part_stat_read(hd, merges[1]),
                            (unsigned long long)part_stat_read(hd, sectors[1]),
                            jiffies_to_msecs(part_stat_read(hd, ticks[1])),
                           hd->in_flight,
                           jiffies_to_msecs(part_stat_read(hd, io_ticks)),
                           jiffies_to_msecs(part_stat_read(hd, time_in_queue))
                        );
        }
        disk_part_iter_exit(&piter);
 
        return 0;
}

static const struct seq_operations diskstats_op = {
        .start        = disk_seqf_start,
        .next        = disk_seqf_next,
        .stop        = disk_seqf_stop,
        .show        = diskstats_show
};

static int diskstats_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &diskstats_op);
}

static const struct file_operations proc_diskstats_operations = {
        .open                = diskstats_open,
        .read                = seq_read,
        .llseek                = seq_lseek,
        .release        = seq_release,
};

static int __init proc_genhd_init(void)
{
        proc_create("diskstats", 0, NULL, &proc_diskstats_operations);
        proc_create("partitions", 0, NULL, &proc_partitions_operations);
        return 0;
}
module_init(proc_genhd_init);
#endif /* CONFIG_PROC_FS */

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(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
        put_device(gd->driverfs_dev);
}

#if 0
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);
#endif  /*  0  */

dev_t blk_lookup_devt(const char *name, int partno)
{
        dev_t devt = MKDEV(0, 0);
        struct class_dev_iter iter;
        struct device *dev;

        class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
        while ((dev = class_dev_iter_next(&iter))) {
                struct gendisk *disk = dev_to_disk(dev);
                struct hd_struct *part;

                if (strcmp(dev->bus_id, name))
                        continue;

                part = disk_get_part(disk, partno);
                if (part) {
                        devt = part_devt(part);
                        disk_put_part(part);
                        break;
                }
                disk_put_part(part);
        }
        class_dev_iter_exit(&iter);
        return devt;
}
EXPORT_SYMBOL(blk_lookup_devt);

struct gendisk *alloc_disk(int minors)
{
        return alloc_disk_node(minors, -1);
}
EXPORT_SYMBOL(alloc_disk);

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_part_stats(&disk->part0)) {
                        kfree(disk);
                        return NULL;
                }
                disk->node_id = node_id;
                if (disk_expand_part_tbl(disk, 0)) {
                        free_part_stats(&disk->part0);
                        kfree(disk);
                        return NULL;
                }
                disk->part_tbl->part[0] = &disk->part0;

                disk->minors = minors;
                rand_initialize_disk(disk);
                disk_to_dev(disk)->class = &block_class;
                disk_to_dev(disk)->type = &disk_type;
                device_initialize(disk_to_dev(disk));
                INIT_WORK(&disk->async_notify,
                        media_change_notify_thread);
        }
        return 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_to_dev(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_to_dev(disk)->kobj);
}

EXPORT_SYMBOL(put_disk);

void set_device_ro(struct block_device *bdev, int flag)
{
        bdev->bd_part->policy = flag;
}

EXPORT_SYMBOL(set_device_ro);

void set_disk_ro(struct gendisk *disk, int flag)
{
        struct disk_part_iter piter;
        struct hd_struct *part;

        disk_part_iter_init(&piter, disk,
                            DISK_PITER_INCL_EMPTY | DISK_PITER_INCL_PART0);
        while ((part = disk_part_iter_next(&piter)))
                part->policy = flag;
        disk_part_iter_exit(&piter);
}

EXPORT_SYMBOL(set_disk_ro);

int bdev_read_only(struct block_device *bdev)
{
        if (!bdev)
                return 0;
        return bdev->bd_part->policy;
}

EXPORT_SYMBOL(bdev_read_only);

int invalidate_partition(struct gendisk *disk, int partno)
{
        int res = 0;
        struct block_device *bdev = bdget_disk(disk, partno);
        if (bdev) {
                fsync_bdev(bdev);
                res = __invalidate_device(bdev);
                bdput(bdev);
        }
        return res;
}

EXPORT_SYMBOL(invalidate_partition);