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