block/genhd.c

   1 /*
   2  *  gendisk handling
   3  */
   4
   5 #include <linux/config.h>
   6 #include <linux/module.h>
   7 #include <linux/fs.h>
   8 #include <linux/genhd.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 struct subsystem block_subsys;
  21
  22 static DEFINE_MUTEX(block_subsys_lock);
  23
  24 /*
  25  * Can be deleted altogether. Later.
  26  *
  27  */
  28 static struct blk_major_name {
  29         struct blk_major_name *next;
  30         int major;
  31         char name[16];
  32 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
  33
  34 /* index in the above - for now: assume no multimajor ranges */
  35 static inline int major_to_index(int major)
  36 {
  37         return major % BLKDEV_MAJOR_HASH_SIZE;
  38 }
  39
  40 #ifdef CONFIG_PROC_FS
  41
  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_subsys_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_subsys_lock);
  51         }
  52 }
  53
  54 #endif /* CONFIG_PROC_FS */
  55
  56 int register_blkdev(unsigned int major, const char *name)
  57 {
  58         struct blk_major_name **n, *p;
  59         int index, ret = 0;
  60
  61         mutex_lock(&block_subsys_lock);
  62
  63         /* temporary */
  64         if (major == 0) {
  65                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
  66                         if (major_names[index] == NULL)
  67                                 break;
  68                 }
  69
  70                 if (index == 0) {
  71                         printk("register_blkdev: failed to get major for %s\n",
  72                                name);
  73                         ret = -EBUSY;
  74                         goto out;
  75                 }
  76                 major = index;
  77                 ret = major;
  78         }
  79
  80         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
  81         if (p == NULL) {
  82                 ret = -ENOMEM;
  83                 goto out;
  84         }
  85
  86         p->major = major;
  87         strlcpy(p->name, name, sizeof(p->name));
  88         p->next = NULL;
  89         index = major_to_index(major);
  90
  91         for (n = &major_names[index]; *n; n = &(*n)->next) {
  92                 if ((*n)->major == major)
  93                         break;
  94         }
  95         if (!*n)
  96                 *n = p;
  97         else
  98                 ret = -EBUSY;
  99
 100         if (ret < 0) {
 101                 printk("register_blkdev: cannot get major %d for %s\n",
 102                        major, name);
 103                 kfree(p);
 104         }
 105 out:
 106         mutex_unlock(&block_subsys_lock);
 107         return ret;
 108 }
 109
 110 EXPORT_SYMBOL(register_blkdev);
 111
 112 /* todo: make void - error printk here */
 113 int unregister_blkdev(unsigned int major, const char *name)
 114 {
 115         struct blk_major_name **n;
 116         struct blk_major_name *p = NULL;
 117         int index = major_to_index(major);
 118         int ret = 0;
 119
 120         mutex_lock(&block_subsys_lock);
 121         for (n = &major_names[index]; *n; n = &(*n)->next)
 122                 if ((*n)->major == major)
 123                         break;
 124         if (!*n || strcmp((*n)->name, name))
 125                 ret = -EINVAL;
 126         else {
 127                 p = *n;
 128                 *n = p->next;
 129         }
 130         mutex_unlock(&block_subsys_lock);
 131         kfree(p);
 132
 133         return ret;
 134 }
 135
 136 EXPORT_SYMBOL(unregister_blkdev);
 137
 138 static struct kobj_map *bdev_map;
 139
 140 /*
 141  * Register device numbers dev..(dev+range-1)
 142  * range must be nonzero
 143  * The hash chain is sorted on range, so that subranges can override.
 144  */
 145 void blk_register_region(dev_t dev, unsigned long range, struct module *module,
 146                          struct kobject *(*probe)(dev_t, int *, void *),
 147                          int (*lock)(dev_t, void *), void *data)
 148 {
 149         kobj_map(bdev_map, dev, range, module, probe, lock, data);
 150 }
 151
 152 EXPORT_SYMBOL(blk_register_region);
 153
 154 void blk_unregister_region(dev_t dev, unsigned long range)
 155 {
 156         kobj_unmap(bdev_map, dev, range);
 157 }
 158
 159 EXPORT_SYMBOL(blk_unregister_region);
 160
 161 static struct kobject *exact_match(dev_t dev, int *part, void *data)
 162 {
 163         struct gendisk *p = data;
 164         return &p->kobj;
 165 }
 166
 167 static int exact_lock(dev_t dev, void *data)
 168 {
 169         struct gendisk *p = data;
 170
 171         if (!get_disk(p))
 172                 return -1;
 173         return 0;
 174 }
 175
 176 /**
 177  * add_disk - add partitioning information to kernel list
 178  * @disk: per-device partitioning information
 179  *
 180  * This function registers the partitioning information in @disk
 181  * with the kernel.
 182  */
 183 void add_disk(struct gendisk *disk)
 184 {
 185         get_device(disk->driverfs_dev);
 186         disk->flags |= GENHD_FL_UP;
 187         blk_register_region(MKDEV(disk->major, disk->first_minor),
 188                             disk->minors, NULL, exact_match, exact_lock, disk);
 189         register_disk(disk);
 190         blk_register_queue(disk);
 191 }
 192
 193 EXPORT_SYMBOL(add_disk);
 194 EXPORT_SYMBOL(del_gendisk);     /* in partitions/check.c */
 195
 196 void unlink_gendisk(struct gendisk *disk)
 197 {
 198         blk_unregister_queue(disk);
 199         blk_unregister_region(MKDEV(disk->major, disk->first_minor),
 200                               disk->minors);
 201 }
 202
 203 #define to_disk(obj) container_of(obj,struct gendisk,kobj)
 204
 205 /**
 206  * get_gendisk - get partitioning information for a given device
 207  * @dev: device to get partitioning information for
 208  *
 209  * This function gets the structure containing partitioning
 210  * information for the given device @dev.
 211  */
 212 struct gendisk *get_gendisk(dev_t dev, int *part)
 213 {
 214         struct kobject *kobj = kobj_lookup(bdev_map, dev, part);
 215         return  kobj ? to_disk(kobj) : NULL;
 216 }
 217
 218 #ifdef CONFIG_PROC_FS
 219 /* iterator */
 220 static void *part_start(struct seq_file *part, loff_t *pos)
 221 {
 222         struct list_head *p;
 223         loff_t l = *pos;
 224
 225         mutex_lock(&block_subsys_lock);
 226         list_for_each(p, &block_subsys.kset.list)
 227                 if (!l--)
 228                         return list_entry(p, struct gendisk, kobj.entry);
 229         return NULL;
 230 }
 231
 232 static void *part_next(struct seq_file *part, void *v, loff_t *pos)
 233 {
 234         struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
 235         ++*pos;
 236         return p==&block_subsys.kset.list ? NULL :
 237                 list_entry(p, struct gendisk, kobj.entry);
 238 }
 239
 240 static void part_stop(struct seq_file *part, void *v)
 241 {
 242         mutex_unlock(&block_subsys_lock);
 243 }
 244
 245 static int show_partition(struct seq_file *part, void *v)
 246 {
 247         struct gendisk *sgp = v;
 248         int n;
 249         char buf[BDEVNAME_SIZE];
 250
 251         if (&sgp->kobj.entry == block_subsys.kset.list.next)
 252                 seq_puts(part, "major minor  #blocks  name\n\n");
 253
 254         /* Don't show non-partitionable removeable devices or empty devices */
 255         if (!get_capacity(sgp) ||
 256                         (sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
 257                 return 0;
 258         if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
 259                 return 0;
 260
 261         /* show the full disk and all non-0 size partitions of it */
 262         seq_printf(part, "%4d  %4d %10llu %s\n",
 263                 sgp->major, sgp->first_minor,
 264                 (unsigned long long)get_capacity(sgp) >> 1,
 265                 disk_name(sgp, 0, buf));
 266         for (n = 0; n < sgp->minors - 1; n++) {
 267                 if (!sgp->part[n])
 268                         continue;
 269                 if (sgp->part[n]->nr_sects == 0)
 270                         continue;
 271                 seq_printf(part, "%4d  %4d %10llu %s\n",
 272                         sgp->major, n + 1 + sgp->first_minor,
 273                         (unsigned long long)sgp->part[n]->nr_sects >> 1 ,
 274                         disk_name(sgp, n + 1, buf));
 275         }
 276
 277         return 0;
 278 }
 279
 280 struct seq_operations partitions_op = {
 281         .start =part_start,
 282         .next = part_next,
 283         .stop = part_stop,
 284         .show = show_partition
 285 };
 286 #endif
 287
 288
 289 extern int blk_dev_init(void);
 290
 291 static struct kobject *base_probe(dev_t dev, int *part, void *data)
 292 {
 293         if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
 294                 /* Make old-style 2.4 aliases work */
 295                 request_module("block-major-%d", MAJOR(dev));
 296         return NULL;
 297 }
 298
 299 static int __init genhd_device_init(void)
 300 {
 301         bdev_map = kobj_map_init(base_probe, &block_subsys_lock);
 302         blk_dev_init();
 303         subsystem_register(&block_subsys);
 304         return 0;
 305 }
 306
 307 subsys_initcall(genhd_device_init);
 308
 309
 310
 311 /*
 312  * kobject & sysfs bindings for block devices
 313  */
 314 static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
 315                               char *page)
 316 {
 317         struct gendisk *disk = to_disk(kobj);
 318         struct disk_attribute *disk_attr =
 319                 container_of(attr,struct disk_attribute,attr);
 320         ssize_t ret = -EIO;
 321
 322         if (disk_attr->show)
 323                 ret = disk_attr->show(disk,page);
 324         return ret;
 325 }
 326
 327 static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
 328                                const char *page, size_t count)
 329 {
 330         struct gendisk *disk = to_disk(kobj);
 331         struct disk_attribute *disk_attr =
 332                 container_of(attr,struct disk_attribute,attr);
 333         ssize_t ret = 0;
 334
 335         if (disk_attr->store)
 336                 ret = disk_attr->store(disk, page, count);
 337         return ret;
 338 }
 339
 340 static struct sysfs_ops disk_sysfs_ops = {
 341         .show   = &disk_attr_show,
 342         .store  = &disk_attr_store,
 343 };
 344
 345 static ssize_t disk_uevent_store(struct gendisk * disk,
 346                                  const char *buf, size_t count)
 347 {
 348         kobject_uevent(&disk->kobj, KOBJ_ADD);
 349         return count;
 350 }
 351 static ssize_t disk_dev_read(struct gendisk * disk, char *page)
 352 {
 353         dev_t base = MKDEV(disk->major, disk->first_minor);
 354         return print_dev_t(page, base);
 355 }
 356 static ssize_t disk_range_read(struct gendisk * disk, char *page)
 357 {
 358         return sprintf(page, "%d\n", disk->minors);
 359 }
 360 static ssize_t disk_removable_read(struct gendisk * disk, char *page)
 361 {
 362         return sprintf(page, "%d\n",
 363                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 364
 365 }
 366 static ssize_t disk_size_read(struct gendisk * disk, char *page)
 367 {
 368         return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk));
 369 }
 370
 371 static ssize_t disk_stats_read(struct gendisk * disk, char *page)
 372 {
 373         preempt_disable();
 374         disk_round_stats(disk);
 375         preempt_enable();
 376         return sprintf(page,
 377                 "%8lu %8lu %8llu %8u "
 378                 "%8lu %8lu %8llu %8u "
 379                 "%8u %8u %8u"
 380                 "\n",
 381                 disk_stat_read(disk, ios[READ]),
 382                 disk_stat_read(disk, merges[READ]),
 383                 (unsigned long long)disk_stat_read(disk, sectors[READ]),
 384                 jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
 385                 disk_stat_read(disk, ios[WRITE]),
 386                 disk_stat_read(disk, merges[WRITE]),
 387                 (unsigned long long)disk_stat_read(disk, sectors[WRITE]),
 388                 jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),
 389                 disk->in_flight,
 390                 jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
 391                 jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
 392 }
 393 static struct disk_attribute disk_attr_uevent = {
 394         .attr = {.name = "uevent", .mode = S_IWUSR },
 395         .store  = disk_uevent_store
 396 };
 397 static struct disk_attribute disk_attr_dev = {
 398         .attr = {.name = "dev", .mode = S_IRUGO },
 399         .show   = disk_dev_read
 400 };
 401 static struct disk_attribute disk_attr_range = {
 402         .attr = {.name = "range", .mode = S_IRUGO },
 403         .show   = disk_range_read
 404 };
 405 static struct disk_attribute disk_attr_removable = {
 406         .attr = {.name = "removable", .mode = S_IRUGO },
 407         .show   = disk_removable_read
 408 };
 409 static struct disk_attribute disk_attr_size = {
 410         .attr = {.name = "size", .mode = S_IRUGO },
 411         .show   = disk_size_read
 412 };
 413 static struct disk_attribute disk_attr_stat = {
 414         .attr = {.name = "stat", .mode = S_IRUGO },
 415         .show   = disk_stats_read
 416 };
 417
 418 static struct attribute * default_attrs[] = {
 419         &disk_attr_uevent.attr,
 420         &disk_attr_dev.attr,
 421         &disk_attr_range.attr,
 422         &disk_attr_removable.attr,
 423         &disk_attr_size.attr,
 424         &disk_attr_stat.attr,
 425         NULL,
 426 };
 427
 428 static void disk_release(struct kobject * kobj)
 429 {
 430         struct gendisk *disk = to_disk(kobj);
 431         put_device(disk->driverfs_dev);
 432         kfree(disk->random);
 433         kfree(disk->part);
 434         free_disk_stats(disk);
 435         kfree(disk);
 436 }
 437
 438 static struct kobj_type ktype_block = {
 439         .release        = disk_release,
 440         .sysfs_ops      = &disk_sysfs_ops,
 441         .default_attrs  = default_attrs,
 442 };
 443
 444 extern struct kobj_type ktype_part;
 445
 446 static int block_uevent_filter(struct kset *kset, struct kobject *kobj)
 447 {
 448         struct kobj_type *ktype = get_ktype(kobj);
 449
 450         return ((ktype == &ktype_block) || (ktype == &ktype_part));
 451 }
 452
 453 static int block_uevent(struct kset *kset, struct kobject *kobj, char **envp,
 454                          int num_envp, char *buffer, int buffer_size)
 455 {
 456         struct kobj_type *ktype = get_ktype(kobj);
 457         struct device *physdev;
 458         struct gendisk *disk;
 459         struct hd_struct *part;
 460         int length = 0;
 461         int i = 0;
 462
 463         if (ktype == &ktype_block) {
 464                 disk = container_of(kobj, struct gendisk, kobj);
 465                 add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
 466                                &length, "MINOR=%u", disk->first_minor);
 467         } else if (ktype == &ktype_part) {
 468                 disk = container_of(kobj->parent, struct gendisk, kobj);
 469                 part = container_of(kobj, struct hd_struct, kobj);
 470                 add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
 471                                &length, "MINOR=%u",
 472                                disk->first_minor + part->partno);
 473         } else
 474                 return 0;
 475
 476         add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
 477                        "MAJOR=%u", disk->major);
 478
 479         /* add physical device, backing this device  */
 480         physdev = disk->driverfs_dev;
 481         if (physdev) {
 482                 char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL);
 483
 484                 add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
 485                                &length, "PHYSDEVPATH=%s", path);
 486                 kfree(path);
 487
 488                 if (physdev->bus)
 489                         add_uevent_var(envp, num_envp, &i,
 490                                        buffer, buffer_size, &length,
 491                                        "PHYSDEVBUS=%s",
 492                                        physdev->bus->name);
 493
 494                 if (physdev->driver)
 495                         add_uevent_var(envp, num_envp, &i,
 496                                        buffer, buffer_size, &length,
 497                                        "PHYSDEVDRIVER=%s",
 498                                        physdev->driver->name);
 499         }
 500
 501         /* terminate, set to next free slot, shrink available space */
 502         envp[i] = NULL;
 503         envp = &envp[i];
 504         num_envp -= i;
 505         buffer = &buffer[length];
 506         buffer_size -= length;
 507
 508         return 0;
 509 }
 510
 511 static struct kset_uevent_ops block_uevent_ops = {
 512         .filter         = block_uevent_filter,
 513         .uevent         = block_uevent,
 514 };
 515
 516 /* declare block_subsys. */
 517 static decl_subsys(block, &ktype_block, &block_uevent_ops);
 518
 519
 520 /*
 521  * aggregate disk stat collector.  Uses the same stats that the sysfs
 522  * entries do, above, but makes them available through one seq_file.
 523  * Watching a few disks may be efficient through sysfs, but watching
 524  * all of them will be more efficient through this interface.
 525  *
 526  * The output looks suspiciously like /proc/partitions with a bunch of
 527  * extra fields.
 528  */
 529
 530 /* iterator */
 531 static void *diskstats_start(struct seq_file *part, loff_t *pos)
 532 {
 533         loff_t k = *pos;
 534         struct list_head *p;
 535
 536         mutex_lock(&block_subsys_lock);
 537         list_for_each(p, &block_subsys.kset.list)
 538                 if (!k--)
 539                         return list_entry(p, struct gendisk, kobj.entry);
 540         return NULL;
 541 }
 542
 543 static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
 544 {
 545         struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
 546         ++*pos;
 547         return p==&block_subsys.kset.list ? NULL :
 548                 list_entry(p, struct gendisk, kobj.entry);
 549 }
 550
 551 static void diskstats_stop(struct seq_file *part, void *v)
 552 {
 553         mutex_unlock(&block_subsys_lock);
 554 }
 555
 556 static int diskstats_show(struct seq_file *s, void *v)
 557 {
 558         struct gendisk *gp = v;
 559         char buf[BDEVNAME_SIZE];
 560         int n = 0;
 561
 562         /*
 563         if (&sgp->kobj.entry == block_subsys.kset.list.next)
 564                 seq_puts(s,     "major minor name"
 565                                 "     rio rmerge rsect ruse wio wmerge "
 566                                 "wsect wuse running use aveq"
 567                                 "\n\n");
 568         */
 569
 570         preempt_disable();
 571         disk_round_stats(gp);
 572         preempt_enable();
 573         seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
 574                 gp->major, n + gp->first_minor, disk_name(gp, n, buf),
 575                 disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
 576                 (unsigned long long)disk_stat_read(gp, sectors[0]),
 577                 jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
 578                 disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
 579                 (unsigned long long)disk_stat_read(gp, sectors[1]),
 580                 jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
 581                 gp->in_flight,
 582                 jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
 583                 jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
 584
 585         /* now show all non-0 size partitions of it */
 586         for (n = 0; n < gp->minors - 1; n++) {
 587                 struct hd_struct *hd = gp->part[n];
 588
 589                 if (hd && hd->nr_sects)
 590                         seq_printf(s, "%4d %4d %s %u %u %u %u\n",
 591                                 gp->major, n + gp->first_minor + 1,
 592                                 disk_name(gp, n + 1, buf),
 593                                 hd->ios[0], hd->sectors[0],
 594                                 hd->ios[1], hd->sectors[1]);
 595         }
 596
 597         return 0;
 598 }
 599
 600 struct seq_operations diskstats_op = {
 601         .start  = diskstats_start,
 602         .next   = diskstats_next,
 603         .stop   = diskstats_stop,
 604         .show   = diskstats_show
 605 };
 606
 607 struct gendisk *alloc_disk(int minors)
 608 {
 609         return alloc_disk_node(minors, -1);
 610 }
 611
 612 struct gendisk *alloc_disk_node(int minors, int node_id)
 613 {
 614         struct gendisk *disk;
 615
 616         disk = kmalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
 617         if (disk) {
 618                 memset(disk, 0, sizeof(struct gendisk));
 619                 if (!init_disk_stats(disk)) {
 620                         kfree(disk);
 621                         return NULL;
 622                 }
 623                 if (minors > 1) {
 624                         int size = (minors - 1) * sizeof(struct hd_struct *);
 625                         disk->part = kmalloc_node(size, GFP_KERNEL, node_id);
 626                         if (!disk->part) {
 627                                 kfree(disk);
 628                                 return NULL;
 629                         }
 630                         memset(disk->part, 0, size);
 631                 }
 632                 disk->minors = minors;
 633                 kobj_set_kset_s(disk,block_subsys);
 634                 kobject_init(&disk->kobj);
 635                 rand_initialize_disk(disk);
 636         }
 637         return disk;
 638 }
 639
 640 EXPORT_SYMBOL(alloc_disk);
 641 EXPORT_SYMBOL(alloc_disk_node);
 642
 643 struct kobject *get_disk(struct gendisk *disk)
 644 {
 645         struct module *owner;
 646         struct kobject *kobj;
 647
 648         if (!disk->fops)
 649                 return NULL;
 650         owner = disk->fops->owner;
 651         if (owner && !try_module_get(owner))
 652                 return NULL;
 653         kobj = kobject_get(&disk->kobj);
 654         if (kobj == NULL) {
 655                 module_put(owner);
 656                 return NULL;
 657         }
 658         return kobj;
 659
 660 }
 661
 662 EXPORT_SYMBOL(get_disk);
 663
 664 void put_disk(struct gendisk *disk)
 665 {
 666         if (disk)
 667                 kobject_put(&disk->kobj);
 668 }
 669
 670 EXPORT_SYMBOL(put_disk);
 671
 672 void set_device_ro(struct block_device *bdev, int flag)
 673 {
 674         if (bdev->bd_contains != bdev)
 675                 bdev->bd_part->policy = flag;
 676         else
 677                 bdev->bd_disk->policy = flag;
 678 }
 679
 680 EXPORT_SYMBOL(set_device_ro);
 681
 682 void set_disk_ro(struct gendisk *disk, int flag)
 683 {
 684         int i;
 685         disk->policy = flag;
 686         for (i = 0; i < disk->minors - 1; i++)
 687                 if (disk->part[i]) disk->part[i]->policy = flag;
 688 }
 689
 690 EXPORT_SYMBOL(set_disk_ro);
 691
 692 int bdev_read_only(struct block_device *bdev)
 693 {
 694         if (!bdev)
 695                 return 0;
 696         else if (bdev->bd_contains != bdev)
 697                 return bdev->bd_part->policy;
 698         else
 699                 return bdev->bd_disk->policy;
 700 }
 701
 702 EXPORT_SYMBOL(bdev_read_only);
 703
 704 int invalidate_partition(struct gendisk *disk, int index)
 705 {
 706         int res = 0;
 707         struct block_device *bdev = bdget_disk(disk, index);
 708         if (bdev) {
 709                 fsync_bdev(bdev);
 710                 res = __invalidate_device(bdev);
 711                 bdput(bdev);
 712         }
 713         return res;
 714 }
 715
 716 EXPORT_SYMBOL(invalidate_partition);