block/genhd.c

   1 /*
   2  *  gendisk handling
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/fs.h>
   7 #include <linux/genhd.h>
   8 #include <linux/kdev_t.h>
   9 #include <linux/kernel.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/init.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/slab.h>
  15 #include <linux/kmod.h>
  16 #include <linux/kobj_map.h>
  17 #include <linux/buffer_head.h>
  18 #include <linux/mutex.h>
  19
  20 static DEFINE_MUTEX(block_class_lock);
  21 #ifndef CONFIG_SYSFS_DEPRECATED
  22 struct kobject *block_depr;
  23 #endif
  24
  25 /*
  26  * Can be deleted altogether. Later.
  27  *
  28  */
  29 static struct blk_major_name {
  30         struct blk_major_name *next;
  31         int major;
  32         char name[16];
  33 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
  34
  35 /* index in the above - for now: assume no multimajor ranges */
  36 static inline int major_to_index(int major)
  37 {
  38         return major % BLKDEV_MAJOR_HASH_SIZE;
  39 }
  40
  41 #ifdef CONFIG_PROC_FS
  42 void blkdev_show(struct seq_file *f, off_t offset)
  43 {
  44         struct blk_major_name *dp;
  45
  46         if (offset < BLKDEV_MAJOR_HASH_SIZE) {
  47                 mutex_lock(&block_class_lock);
  48                 for (dp = major_names[offset]; dp; dp = dp->next)
  49                         seq_printf(f, "%3d %s\n", dp->major, dp->name);
  50                 mutex_unlock(&block_class_lock);
  51         }
  52 }
  53 #endif /* CONFIG_PROC_FS */
  54
  55 int register_blkdev(unsigned int major, const char *name)
  56 {
  57         struct blk_major_name **n, *p;
  58         int index, ret = 0;
  59
  60         mutex_lock(&block_class_lock);
  61
  62         /* temporary */
  63         if (major == 0) {
  64                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
  65                         if (major_names[index] == NULL)
  66                                 break;
  67                 }
  68
  69                 if (index == 0) {
  70                         printk("register_blkdev: failed to get major for %s\n",
  71                                name);
  72                         ret = -EBUSY;
  73                         goto out;
  74                 }
  75                 major = index;
  76                 ret = major;
  77         }
  78
  79         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
  80         if (p == NULL) {
  81                 ret = -ENOMEM;
  82                 goto out;
  83         }
  84
  85         p->major = major;
  86         strlcpy(p->name, name, sizeof(p->name));
  87         p->next = NULL;
  88         index = major_to_index(major);
  89
  90         for (n = &major_names[index]; *n; n = &(*n)->next) {
  91                 if ((*n)->major == major)
  92                         break;
  93         }
  94         if (!*n)
  95                 *n = p;
  96         else
  97                 ret = -EBUSY;
  98
  99         if (ret < 0) {
 100                 printk("register_blkdev: cannot get major %d for %s\n",
 101                        major, name);
 102                 kfree(p);
 103         }
 104 out:
 105         mutex_unlock(&block_class_lock);
 106         return ret;
 107 }
 108
 109 EXPORT_SYMBOL(register_blkdev);
 110
 111 void unregister_blkdev(unsigned int major, const char *name)
 112 {
 113         struct blk_major_name **n;
 114         struct blk_major_name *p = NULL;
 115         int index = major_to_index(major);
 116
 117         mutex_lock(&block_class_lock);
 118         for (n = &major_names[index]; *n; n = &(*n)->next)
 119                 if ((*n)->major == major)
 120                         break;
 121         if (!*n || strcmp((*n)->name, name)) {
 122                 WARN_ON(1);
 123         } else {
 124                 p = *n;
 125                 *n = p->next;
 126         }
 127         mutex_unlock(&block_class_lock);
 128         kfree(p);
 129 }
 130
 131 EXPORT_SYMBOL(unregister_blkdev);
 132
 133 static struct kobj_map *bdev_map;
 134
 135 /*
 136  * Register device numbers dev..(dev+range-1)
 137  * range must be nonzero
 138  * The hash chain is sorted on range, so that subranges can override.
 139  */
 140 void blk_register_region(dev_t devt, unsigned long range, struct module *module,
 141                          struct kobject *(*probe)(dev_t, int *, void *),
 142                          int (*lock)(dev_t, void *), void *data)
 143 {
 144         kobj_map(bdev_map, devt, range, module, probe, lock, data);
 145 }
 146
 147 EXPORT_SYMBOL(blk_register_region);
 148
 149 void blk_unregister_region(dev_t devt, unsigned long range)
 150 {
 151         kobj_unmap(bdev_map, devt, range);
 152 }
 153
 154 EXPORT_SYMBOL(blk_unregister_region);
 155
 156 static struct kobject *exact_match(dev_t devt, int *part, void *data)
 157 {
 158         struct gendisk *p = data;
 159
 160         return &p->dev.kobj;
 161 }
 162
 163 static int exact_lock(dev_t devt, void *data)
 164 {
 165         struct gendisk *p = data;
 166
 167         if (!get_disk(p))
 168                 return -1;
 169         return 0;
 170 }
 171
 172 /**
 173  * add_disk - add partitioning information to kernel list
 174  * @disk: per-device partitioning information
 175  *
 176  * This function registers the partitioning information in @disk
 177  * with the kernel.
 178  */
 179 void add_disk(struct gendisk *disk)
 180 {
 181         disk->flags |= GENHD_FL_UP;
 182         blk_register_region(MKDEV(disk->major, disk->first_minor),
 183                             disk->minors, NULL, exact_match, exact_lock, disk);
 184         register_disk(disk);
 185         blk_register_queue(disk);
 186 }
 187
 188 EXPORT_SYMBOL(add_disk);
 189 EXPORT_SYMBOL(del_gendisk);     /* in partitions/check.c */
 190
 191 void unlink_gendisk(struct gendisk *disk)
 192 {
 193         blk_unregister_queue(disk);
 194         blk_unregister_region(MKDEV(disk->major, disk->first_minor),
 195                               disk->minors);
 196 }
 197
 198 /**
 199  * get_gendisk - get partitioning information for a given device
 200  * @dev: device to get partitioning information for
 201  *
 202  * This function gets the structure containing partitioning
 203  * information for the given device @dev.
 204  */
 205 struct gendisk *get_gendisk(dev_t devt, int *part)
 206 {
 207         struct kobject *kobj = kobj_lookup(bdev_map, devt, part);
 208         struct device *dev = kobj_to_dev(kobj);
 209
 210         return  kobj ? dev_to_disk(dev) : NULL;
 211 }
 212
 213 /*
 214  * print a full list of all partitions - intended for places where the root
 215  * filesystem can't be mounted and thus to give the victim some idea of what
 216  * went wrong
 217  */
 218 void __init printk_all_partitions(void)
 219 {
 220         struct device *dev;
 221         struct gendisk *sgp;
 222         char buf[BDEVNAME_SIZE];
 223         int n;
 224
 225         mutex_lock(&block_class_lock);
 226         /* For each block device... */
 227         list_for_each_entry(dev, &block_class.devices, node) {
 228                 if (dev->type != &disk_type)
 229                         continue;
 230                 sgp = dev_to_disk(dev);
 231                 /*
 232                  * Don't show empty devices or things that have been surpressed
 233                  */
 234                 if (get_capacity(sgp) == 0 ||
 235                     (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
 236                         continue;
 237
 238                 /*
 239                  * Note, unlike /proc/partitions, I am showing the numbers in
 240                  * hex - the same format as the root= option takes.
 241                  */
 242                 printk("%02x%02x %10llu %s",
 243                         sgp->major, sgp->first_minor,
 244                         (unsigned long long)get_capacity(sgp) >> 1,
 245                         disk_name(sgp, 0, buf));
 246                 if (sgp->driverfs_dev != NULL &&
 247                     sgp->driverfs_dev->driver != NULL)
 248                         printk(" driver: %s\n",
 249                                 sgp->driverfs_dev->driver->name);
 250                 else
 251                         printk(" (driver?)\n");
 252
 253                 /* now show the partitions */
 254                 for (n = 0; n < sgp->minors - 1; ++n) {
 255                         if (sgp->part[n] == NULL)
 256                                 continue;
 257                         if (sgp->part[n]->nr_sects == 0)
 258                                 continue;
 259                         printk("  %02x%02x %10llu %s\n",
 260                                 sgp->major, n + 1 + sgp->first_minor,
 261                                 (unsigned long long)sgp->part[n]->nr_sects >> 1,
 262                                 disk_name(sgp, n + 1, buf));
 263                 }
 264         }
 265
 266         mutex_unlock(&block_class_lock);
 267 }
 268
 269 #ifdef CONFIG_PROC_FS
 270 /* iterator */
 271 static void *part_start(struct seq_file *part, loff_t *pos)
 272 {
 273         loff_t k = *pos;
 274         struct device *dev;
 275
 276         mutex_lock(&block_class_lock);
 277         list_for_each_entry(dev, &block_class.devices, node) {
 278                 if (dev->type != &disk_type)
 279                         continue;
 280                 if (!k--)
 281                         return dev_to_disk(dev);
 282         }
 283         return NULL;
 284 }
 285
 286 static void *part_next(struct seq_file *part, void *v, loff_t *pos)
 287 {
 288         struct gendisk *gp = v;
 289         struct device *dev;
 290         ++*pos;
 291         list_for_each_entry(dev, &gp->dev.node, node) {
 292                 if (&dev->node == &block_class.devices)
 293                         return NULL;
 294                 if (dev->type == &disk_type)
 295                         return dev_to_disk(dev);
 296         }
 297         return NULL;
 298 }
 299
 300 static void part_stop(struct seq_file *part, void *v)
 301 {
 302         mutex_unlock(&block_class_lock);
 303 }
 304
 305 static int show_partition(struct seq_file *part, void *v)
 306 {
 307         struct gendisk *sgp = v;
 308         int n;
 309         char buf[BDEVNAME_SIZE];
 310
 311         if (&sgp->dev.node == block_class.devices.next)
 312                 seq_puts(part, "major minor  #blocks  name\n\n");
 313
 314         /* Don't show non-partitionable removeable devices or empty devices */
 315         if (!get_capacity(sgp) ||
 316                         (sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
 317                 return 0;
 318         if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
 319                 return 0;
 320
 321         /* show the full disk and all non-0 size partitions of it */
 322         seq_printf(part, "%4d  %4d %10llu %s\n",
 323                 sgp->major, sgp->first_minor,
 324                 (unsigned long long)get_capacity(sgp) >> 1,
 325                 disk_name(sgp, 0, buf));
 326         for (n = 0; n < sgp->minors - 1; n++) {
 327                 if (!sgp->part[n])
 328                         continue;
 329                 if (sgp->part[n]->nr_sects == 0)
 330                         continue;
 331                 seq_printf(part, "%4d  %4d %10llu %s\n",
 332                         sgp->major, n + 1 + sgp->first_minor,
 333                         (unsigned long long)sgp->part[n]->nr_sects >> 1 ,
 334                         disk_name(sgp, n + 1, buf));
 335         }
 336
 337         return 0;
 338 }
 339
 340 struct seq_operations partitions_op = {
 341         .start  = part_start,
 342         .next   = part_next,
 343         .stop   = part_stop,
 344         .show   = show_partition
 345 };
 346 #endif
 347
 348
 349 extern int blk_dev_init(void);
 350
 351 static struct kobject *base_probe(dev_t devt, int *part, void *data)
 352 {
 353         if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
 354                 /* Make old-style 2.4 aliases work */
 355                 request_module("block-major-%d", MAJOR(devt));
 356         return NULL;
 357 }
 358
 359 static int __init genhd_device_init(void)
 360 {
 361         class_register(&block_class);
 362         bdev_map = kobj_map_init(base_probe, &block_class_lock);
 363         blk_dev_init();
 364
 365 #ifndef CONFIG_SYSFS_DEPRECATED
 366         /* create top-level block dir */
 367         block_depr = kobject_create_and_add("block", NULL);
 368 #endif
 369         return 0;
 370 }
 371
 372 subsys_initcall(genhd_device_init);
 373
 374 static ssize_t disk_range_show(struct device *dev,
 375                                struct device_attribute *attr, char *buf)
 376 {
 377         struct gendisk *disk = dev_to_disk(dev);
 378
 379         return sprintf(buf, "%d\n", disk->minors);
 380 }
 381
 382 static ssize_t disk_removable_show(struct device *dev,
 383                                    struct device_attribute *attr, char *buf)
 384 {
 385         struct gendisk *disk = dev_to_disk(dev);
 386
 387         return sprintf(buf, "%d\n",
 388                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 389 }
 390
 391 static ssize_t disk_size_show(struct device *dev,
 392                               struct device_attribute *attr, char *buf)
 393 {
 394         struct gendisk *disk = dev_to_disk(dev);
 395
 396         return sprintf(buf, "%llu\n", (unsigned long long)get_capacity(disk));
 397 }
 398
 399 static ssize_t disk_capability_show(struct device *dev,
 400                                     struct device_attribute *attr, char *buf)
 401 {
 402         struct gendisk *disk = dev_to_disk(dev);
 403
 404         return sprintf(buf, "%x\n", disk->flags);
 405 }
 406
 407 static ssize_t disk_stat_show(struct device *dev,
 408                               struct device_attribute *attr, char *buf)
 409 {
 410         struct gendisk *disk = dev_to_disk(dev);
 411
 412         preempt_disable();
 413         disk_round_stats(disk);
 414         preempt_enable();
 415         return sprintf(buf,
 416                 "%8lu %8lu %8llu %8u "
 417                 "%8lu %8lu %8llu %8u "
 418                 "%8u %8u %8u"
 419                 "\n",
 420                 disk_stat_read(disk, ios[READ]),
 421                 disk_stat_read(disk, merges[READ]),
 422                 (unsigned long long)disk_stat_read(disk, sectors[READ]),
 423                 jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
 424                 disk_stat_read(disk, ios[WRITE]),
 425                 disk_stat_read(disk, merges[WRITE]),
 426                 (unsigned long long)disk_stat_read(disk, sectors[WRITE]),
 427                 jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),
 428                 disk->in_flight,
 429                 jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
 430                 jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
 431 }
 432
 433 #ifdef CONFIG_FAIL_MAKE_REQUEST
 434 static ssize_t disk_fail_show(struct device *dev,
 435                               struct device_attribute *attr, char *buf)
 436 {
 437         struct gendisk *disk = dev_to_disk(dev);
 438
 439         return sprintf(buf, "%d\n", disk->flags & GENHD_FL_FAIL ? 1 : 0);
 440 }
 441
 442 static ssize_t disk_fail_store(struct device *dev,
 443                                struct device_attribute *attr,
 444                                const char *buf, size_t count)
 445 {
 446         struct gendisk *disk = dev_to_disk(dev);
 447         int i;
 448
 449         if (count > 0 && sscanf(buf, "%d", &i) > 0) {
 450                 if (i == 0)
 451                         disk->flags &= ~GENHD_FL_FAIL;
 452                 else
 453                         disk->flags |= GENHD_FL_FAIL;
 454         }
 455
 456         return count;
 457 }
 458
 459 #endif
 460
 461 static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
 462 static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
 463 static DEVICE_ATTR(size, S_IRUGO, disk_size_show, NULL);
 464 static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
 465 static DEVICE_ATTR(stat, S_IRUGO, disk_stat_show, NULL);
 466 #ifdef CONFIG_FAIL_MAKE_REQUEST
 467 static struct device_attribute dev_attr_fail =
 468         __ATTR(make-it-fail, S_IRUGO|S_IWUSR, disk_fail_show, disk_fail_store);
 469 #endif
 470
 471 static struct attribute *disk_attrs[] = {
 472         &dev_attr_range.attr,
 473         &dev_attr_removable.attr,
 474         &dev_attr_size.attr,
 475         &dev_attr_capability.attr,
 476         &dev_attr_stat.attr,
 477 #ifdef CONFIG_FAIL_MAKE_REQUEST
 478         &dev_attr_fail.attr,
 479 #endif
 480         NULL
 481 };
 482
 483 static struct attribute_group disk_attr_group = {
 484         .attrs = disk_attrs,
 485 };
 486
 487 static struct attribute_group *disk_attr_groups[] = {
 488         &disk_attr_group,
 489         NULL
 490 };
 491
 492 static void disk_release(struct device *dev)
 493 {
 494         struct gendisk *disk = dev_to_disk(dev);
 495
 496         kfree(disk->random);
 497         kfree(disk->part);
 498         free_disk_stats(disk);
 499         kfree(disk);
 500 }
 501 struct class block_class = {
 502         .name           = "block",
 503 };
 504
 505 struct device_type disk_type = {
 506         .name           = "disk",
 507         .groups         = disk_attr_groups,
 508         .release        = disk_release,
 509 };
 510
 511 /*
 512  * aggregate disk stat collector.  Uses the same stats that the sysfs
 513  * entries do, above, but makes them available through one seq_file.
 514  *
 515  * The output looks suspiciously like /proc/partitions with a bunch of
 516  * extra fields.
 517  */
 518
 519 static void *diskstats_start(struct seq_file *part, loff_t *pos)
 520 {
 521         loff_t k = *pos;
 522         struct device *dev;
 523
 524         mutex_lock(&block_class_lock);
 525         list_for_each_entry(dev, &block_class.devices, node) {
 526                 if (dev->type != &disk_type)
 527                         continue;
 528                 if (!k--)
 529                         return dev_to_disk(dev);
 530         }
 531         return NULL;
 532 }
 533
 534 static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
 535 {
 536         struct gendisk *gp = v;
 537         struct device *dev;
 538
 539         ++*pos;
 540         list_for_each_entry(dev, &gp->dev.node, node) {
 541                 if (&dev->node == &block_class.devices)
 542                         return NULL;
 543                 if (dev->type == &disk_type)
 544                         return dev_to_disk(dev);
 545         }
 546         return NULL;
 547 }
 548
 549 static void diskstats_stop(struct seq_file *part, void *v)
 550 {
 551         mutex_unlock(&block_class_lock);
 552 }
 553
 554 static int diskstats_show(struct seq_file *s, void *v)
 555 {
 556         struct gendisk *gp = v;
 557         char buf[BDEVNAME_SIZE];
 558         int n = 0;
 559
 560         /*
 561         if (&gp->dev.kobj.entry == block_class.devices.next)
 562                 seq_puts(s,     "major minor name"
 563                                 "     rio rmerge rsect ruse wio wmerge "
 564                                 "wsect wuse running use aveq"
 565                                 "\n\n");
 566         */
 567
 568         preempt_disable();
 569         disk_round_stats(gp);
 570         preempt_enable();
 571         seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
 572                 gp->major, n + gp->first_minor, disk_name(gp, n, buf),
 573                 disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
 574                 (unsigned long long)disk_stat_read(gp, sectors[0]),
 575                 jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
 576                 disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
 577                 (unsigned long long)disk_stat_read(gp, sectors[1]),
 578                 jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
 579                 gp->in_flight,
 580                 jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
 581                 jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
 582
 583         /* now show all non-0 size partitions of it */
 584         for (n = 0; n < gp->minors - 1; n++) {
 585                 struct hd_struct *hd = gp->part[n];
 586
 587                 if (hd && hd->nr_sects)
 588                         seq_printf(s, "%4d %4d %s %u %u %u %u\n",
 589                                 gp->major, n + gp->first_minor + 1,
 590                                 disk_name(gp, n + 1, buf),
 591                                 hd->ios[0], hd->sectors[0],
 592                                 hd->ios[1], hd->sectors[1]);
 593         }
 594
 595         return 0;
 596 }
 597
 598 struct seq_operations diskstats_op = {
 599         .start  = diskstats_start,
 600         .next   = diskstats_next,
 601         .stop   = diskstats_stop,
 602         .show   = diskstats_show
 603 };
 604
 605 static void media_change_notify_thread(struct work_struct *work)
 606 {
 607         struct gendisk *gd = container_of(work, struct gendisk, async_notify);
 608         char event[] = "MEDIA_CHANGE=1";
 609         char *envp[] = { event, NULL };
 610
 611         /*
 612          * set enviroment vars to indicate which event this is for
 613          * so that user space will know to go check the media status.
 614          */
 615         kobject_uevent_env(&gd->dev.kobj, KOBJ_CHANGE, envp);
 616         put_device(gd->driverfs_dev);
 617 }
 618
 619 void genhd_media_change_notify(struct gendisk *disk)
 620 {
 621         get_device(disk->driverfs_dev);
 622         schedule_work(&disk->async_notify);
 623 }
 624 EXPORT_SYMBOL_GPL(genhd_media_change_notify);
 625
 626 dev_t blk_lookup_devt(const char *name)
 627 {
 628         struct device *dev;
 629         dev_t devt = MKDEV(0, 0);
 630
 631         mutex_lock(&block_class_lock);
 632         list_for_each_entry(dev, &block_class.devices, node) {
 633                 if (strcmp(dev->bus_id, name) == 0) {
 634                         devt = dev->devt;
 635                         break;
 636                 }
 637         }
 638         mutex_unlock(&block_class_lock);
 639
 640         return devt;
 641 }
 642
 643 EXPORT_SYMBOL(blk_lookup_devt);
 644
 645 struct gendisk *alloc_disk(int minors)
 646 {
 647         return alloc_disk_node(minors, -1);
 648 }
 649
 650 struct gendisk *alloc_disk_node(int minors, int node_id)
 651 {
 652         struct gendisk *disk;
 653
 654         disk = kmalloc_node(sizeof(struct gendisk),
 655                                 GFP_KERNEL | __GFP_ZERO, node_id);
 656         if (disk) {
 657                 if (!init_disk_stats(disk)) {
 658                         kfree(disk);
 659                         return NULL;
 660                 }
 661                 if (minors > 1) {
 662                         int size = (minors - 1) * sizeof(struct hd_struct *);
 663                         disk->part = kmalloc_node(size,
 664                                 GFP_KERNEL | __GFP_ZERO, node_id);
 665                         if (!disk->part) {
 666                                 free_disk_stats(disk);
 667                                 kfree(disk);
 668                                 return NULL;
 669                         }
 670                 }
 671                 disk->minors = minors;
 672                 rand_initialize_disk(disk);
 673                 disk->dev.class = &block_class;
 674                 disk->dev.type = &disk_type;
 675                 device_initialize(&disk->dev);
 676                 INIT_WORK(&disk->async_notify,
 677                         media_change_notify_thread);
 678         }
 679         return disk;
 680 }
 681
 682 EXPORT_SYMBOL(alloc_disk);
 683 EXPORT_SYMBOL(alloc_disk_node);
 684
 685 struct kobject *get_disk(struct gendisk *disk)
 686 {
 687         struct module *owner;
 688         struct kobject *kobj;
 689
 690         if (!disk->fops)
 691                 return NULL;
 692         owner = disk->fops->owner;
 693         if (owner && !try_module_get(owner))
 694                 return NULL;
 695         kobj = kobject_get(&disk->dev.kobj);
 696         if (kobj == NULL) {
 697                 module_put(owner);
 698                 return NULL;
 699         }
 700         return kobj;
 701
 702 }
 703
 704 EXPORT_SYMBOL(get_disk);
 705
 706 void put_disk(struct gendisk *disk)
 707 {
 708         if (disk)
 709                 kobject_put(&disk->dev.kobj);
 710 }
 711
 712 EXPORT_SYMBOL(put_disk);
 713
 714 void set_device_ro(struct block_device *bdev, int flag)
 715 {
 716         if (bdev->bd_contains != bdev)
 717                 bdev->bd_part->policy = flag;
 718         else
 719                 bdev->bd_disk->policy = flag;
 720 }
 721
 722 EXPORT_SYMBOL(set_device_ro);
 723
 724 void set_disk_ro(struct gendisk *disk, int flag)
 725 {
 726         int i;
 727         disk->policy = flag;
 728         for (i = 0; i < disk->minors - 1; i++)
 729                 if (disk->part[i]) disk->part[i]->policy = flag;
 730 }
 731
 732 EXPORT_SYMBOL(set_disk_ro);
 733
 734 int bdev_read_only(struct block_device *bdev)
 735 {
 736         if (!bdev)
 737                 return 0;
 738         else if (bdev->bd_contains != bdev)
 739                 return bdev->bd_part->policy;
 740         else
 741                 return bdev->bd_disk->policy;
 742 }
 743
 744 EXPORT_SYMBOL(bdev_read_only);
 745
 746 int invalidate_partition(struct gendisk *disk, int index)
 747 {
 748         int res = 0;
 749         struct block_device *bdev = bdget_disk(disk, index);
 750         if (bdev) {
 751                 fsync_bdev(bdev);
 752                 res = __invalidate_device(bdev);
 753                 bdput(bdev);
 754         }
 755         return res;
 756 }
 757
 758 EXPORT_SYMBOL(invalidate_partition);