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         int err;
 299
 300         bdev_map = kobj_map_init(base_probe, &block_subsys_lock);
 301         blk_dev_init();
 302         err = subsystem_register(&block_subsys);
 303         if (err < 0)
 304                 printk(KERN_WARNING "%s: subsystem_register error: %d\n",
 305                         __FUNCTION__, err);
 306         return err;
 307 }
 308
 309 subsys_initcall(genhd_device_init);
 310
 311
 312
 313 /*
 314  * kobject & sysfs bindings for block devices
 315  */
 316 static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
 317                               char *page)
 318 {
 319         struct gendisk *disk = to_disk(kobj);
 320         struct disk_attribute *disk_attr =
 321                 container_of(attr,struct disk_attribute,attr);
 322         ssize_t ret = -EIO;
 323
 324         if (disk_attr->show)
 325                 ret = disk_attr->show(disk,page);
 326         return ret;
 327 }
 328
 329 static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
 330                                const char *page, size_t count)
 331 {
 332         struct gendisk *disk = to_disk(kobj);
 333         struct disk_attribute *disk_attr =
 334                 container_of(attr,struct disk_attribute,attr);
 335         ssize_t ret = 0;
 336
 337         if (disk_attr->store)
 338                 ret = disk_attr->store(disk, page, count);
 339         return ret;
 340 }
 341
 342 static struct sysfs_ops disk_sysfs_ops = {
 343         .show   = &disk_attr_show,
 344         .store  = &disk_attr_store,
 345 };
 346
 347 static ssize_t disk_uevent_store(struct gendisk * disk,
 348                                  const char *buf, size_t count)
 349 {
 350         kobject_uevent(&disk->kobj, KOBJ_ADD);
 351         return count;
 352 }
 353 static ssize_t disk_dev_read(struct gendisk * disk, char *page)
 354 {
 355         dev_t base = MKDEV(disk->major, disk->first_minor);
 356         return print_dev_t(page, base);
 357 }
 358 static ssize_t disk_range_read(struct gendisk * disk, char *page)
 359 {
 360         return sprintf(page, "%d\n", disk->minors);
 361 }
 362 static ssize_t disk_removable_read(struct gendisk * disk, char *page)
 363 {
 364         return sprintf(page, "%d\n",
 365                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 366
 367 }
 368 static ssize_t disk_size_read(struct gendisk * disk, char *page)
 369 {
 370         return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk));
 371 }
 372
 373 static ssize_t disk_stats_read(struct gendisk * disk, char *page)
 374 {
 375         preempt_disable();
 376         disk_round_stats(disk);
 377         preempt_enable();
 378         return sprintf(page,
 379                 "%8lu %8lu %8llu %8u "
 380                 "%8lu %8lu %8llu %8u "
 381                 "%8u %8u %8u"
 382                 "\n",
 383                 disk_stat_read(disk, ios[READ]),
 384                 disk_stat_read(disk, merges[READ]),
 385                 (unsigned long long)disk_stat_read(disk, sectors[READ]),
 386                 jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
 387                 disk_stat_read(disk, ios[WRITE]),
 388                 disk_stat_read(disk, merges[WRITE]),
 389                 (unsigned long long)disk_stat_read(disk, sectors[WRITE]),
 390                 jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),
 391                 disk->in_flight,
 392                 jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
 393                 jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
 394 }
 395 static struct disk_attribute disk_attr_uevent = {
 396         .attr = {.name = "uevent", .mode = S_IWUSR },
 397         .store  = disk_uevent_store
 398 };
 399 static struct disk_attribute disk_attr_dev = {
 400         .attr = {.name = "dev", .mode = S_IRUGO },
 401         .show   = disk_dev_read
 402 };
 403 static struct disk_attribute disk_attr_range = {
 404         .attr = {.name = "range", .mode = S_IRUGO },
 405         .show   = disk_range_read
 406 };
 407 static struct disk_attribute disk_attr_removable = {
 408         .attr = {.name = "removable", .mode = S_IRUGO },
 409         .show   = disk_removable_read
 410 };
 411 static struct disk_attribute disk_attr_size = {
 412         .attr = {.name = "size", .mode = S_IRUGO },
 413         .show   = disk_size_read
 414 };
 415 static struct disk_attribute disk_attr_stat = {
 416         .attr = {.name = "stat", .mode = S_IRUGO },
 417         .show   = disk_stats_read
 418 };
 419
 420 static struct attribute * default_attrs[] = {
 421         &disk_attr_uevent.attr,
 422         &disk_attr_dev.attr,
 423         &disk_attr_range.attr,
 424         &disk_attr_removable.attr,
 425         &disk_attr_size.attr,
 426         &disk_attr_stat.attr,
 427         NULL,
 428 };
 429
 430 static void disk_release(struct kobject * kobj)
 431 {
 432         struct gendisk *disk = to_disk(kobj);
 433         kfree(disk->random);
 434         kfree(disk->part);
 435         free_disk_stats(disk);
 436         kfree(disk);
 437 }
 438
 439 static struct kobj_type ktype_block = {
 440         .release        = disk_release,
 441         .sysfs_ops      = &disk_sysfs_ops,
 442         .default_attrs  = default_attrs,
 443 };
 444
 445 extern struct kobj_type ktype_part;
 446
 447 static int block_uevent_filter(struct kset *kset, struct kobject *kobj)
 448 {
 449         struct kobj_type *ktype = get_ktype(kobj);
 450
 451         return ((ktype == &ktype_block) || (ktype == &ktype_part));
 452 }
 453
 454 static int block_uevent(struct kset *kset, struct kobject *kobj, char **envp,
 455                          int num_envp, char *buffer, int buffer_size)
 456 {
 457         struct kobj_type *ktype = get_ktype(kobj);
 458         struct device *physdev;
 459         struct gendisk *disk;
 460         struct hd_struct *part;
 461         int length = 0;
 462         int i = 0;
 463
 464         if (ktype == &ktype_block) {
 465                 disk = container_of(kobj, struct gendisk, kobj);
 466                 add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
 467                                &length, "MINOR=%u", disk->first_minor);
 468         } else if (ktype == &ktype_part) {
 469                 disk = container_of(kobj->parent, struct gendisk, kobj);
 470                 part = container_of(kobj, struct hd_struct, kobj);
 471                 add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
 472                                &length, "MINOR=%u",
 473                                disk->first_minor + part->partno);
 474         } else
 475                 return 0;
 476
 477         add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
 478                        "MAJOR=%u", disk->major);
 479
 480         /* add physical device, backing this device  */
 481         physdev = disk->driverfs_dev;
 482         if (physdev) {
 483                 char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL);
 484
 485                 add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
 486                                &length, "PHYSDEVPATH=%s", path);
 487                 kfree(path);
 488
 489                 if (physdev->bus)
 490                         add_uevent_var(envp, num_envp, &i,
 491                                        buffer, buffer_size, &length,
 492                                        "PHYSDEVBUS=%s",
 493                                        physdev->bus->name);
 494
 495                 if (physdev->driver)
 496                         add_uevent_var(envp, num_envp, &i,
 497                                        buffer, buffer_size, &length,
 498                                        "PHYSDEVDRIVER=%s",
 499                                        physdev->driver->name);
 500         }
 501
 502         /* terminate, set to next free slot, shrink available space */
 503         envp[i] = NULL;
 504         envp = &envp[i];
 505         num_envp -= i;
 506         buffer = &buffer[length];
 507         buffer_size -= length;
 508
 509         return 0;
 510 }
 511
 512 static struct kset_uevent_ops block_uevent_ops = {
 513         .filter         = block_uevent_filter,
 514         .uevent         = block_uevent,
 515 };
 516
 517 decl_subsys(block, &ktype_block, &block_uevent_ops);
 518
 519 /*
 520  * aggregate disk stat collector.  Uses the same stats that the sysfs
 521  * entries do, above, but makes them available through one seq_file.
 522  * Watching a few disks may be efficient through sysfs, but watching
 523  * all of them will be more efficient through this interface.
 524  *
 525  * The output looks suspiciously like /proc/partitions with a bunch of
 526  * extra fields.
 527  */
 528
 529 /* iterator */
 530 static void *diskstats_start(struct seq_file *part, loff_t *pos)
 531 {
 532         loff_t k = *pos;
 533         struct list_head *p;
 534
 535         mutex_lock(&block_subsys_lock);
 536         list_for_each(p, &block_subsys.kset.list)
 537                 if (!k--)
 538                         return list_entry(p, struct gendisk, kobj.entry);
 539         return NULL;
 540 }
 541
 542 static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
 543 {
 544         struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
 545         ++*pos;
 546         return p==&block_subsys.kset.list ? NULL :
 547                 list_entry(p, struct gendisk, kobj.entry);
 548 }
 549
 550 static void diskstats_stop(struct seq_file *part, void *v)
 551 {
 552         mutex_unlock(&block_subsys_lock);
 553 }
 554
 555 static int diskstats_show(struct seq_file *s, void *v)
 556 {
 557         struct gendisk *gp = v;
 558         char buf[BDEVNAME_SIZE];
 559         int n = 0;
 560
 561         /*
 562         if (&sgp->kobj.entry == block_subsys.kset.list.next)
 563                 seq_puts(s,     "major minor name"
 564                                 "     rio rmerge rsect ruse wio wmerge "
 565                                 "wsect wuse running use aveq"
 566                                 "\n\n");
 567         */
 568
 569         preempt_disable();
 570         disk_round_stats(gp);
 571         preempt_enable();
 572         seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
 573                 gp->major, n + gp->first_minor, disk_name(gp, n, buf),
 574                 disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
 575                 (unsigned long long)disk_stat_read(gp, sectors[0]),
 576                 jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
 577                 disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
 578                 (unsigned long long)disk_stat_read(gp, sectors[1]),
 579                 jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
 580                 gp->in_flight,
 581                 jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
 582                 jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
 583
 584         /* now show all non-0 size partitions of it */
 585         for (n = 0; n < gp->minors - 1; n++) {
 586                 struct hd_struct *hd = gp->part[n];
 587
 588                 if (hd && hd->nr_sects)
 589                         seq_printf(s, "%4d %4d %s %u %u %u %u\n",
 590                                 gp->major, n + gp->first_minor + 1,
 591                                 disk_name(gp, n + 1, buf),
 592                                 hd->ios[0], hd->sectors[0],
 593                                 hd->ios[1], hd->sectors[1]);
 594         }
 595
 596         return 0;
 597 }
 598
 599 struct seq_operations diskstats_op = {
 600         .start  = diskstats_start,
 601         .next   = diskstats_next,
 602         .stop   = diskstats_stop,
 603         .show   = diskstats_show
 604 };
 605
 606 struct gendisk *alloc_disk(int minors)
 607 {
 608         return alloc_disk_node(minors, -1);
 609 }
 610
 611 struct gendisk *alloc_disk_node(int minors, int node_id)
 612 {
 613         struct gendisk *disk;
 614
 615         disk = kmalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
 616         if (disk) {
 617                 memset(disk, 0, sizeof(struct gendisk));
 618                 if (!init_disk_stats(disk)) {
 619                         kfree(disk);
 620                         return NULL;
 621                 }
 622                 if (minors > 1) {
 623                         int size = (minors - 1) * sizeof(struct hd_struct *);
 624                         disk->part = kmalloc_node(size, GFP_KERNEL, node_id);
 625                         if (!disk->part) {
 626                                 kfree(disk);
 627                                 return NULL;
 628                         }
 629                         memset(disk->part, 0, size);
 630                 }
 631                 disk->minors = minors;
 632                 kobj_set_kset_s(disk,block_subsys);
 633                 kobject_init(&disk->kobj);
 634                 rand_initialize_disk(disk);
 635         }
 636         return disk;
 637 }
 638
 639 EXPORT_SYMBOL(alloc_disk);
 640 EXPORT_SYMBOL(alloc_disk_node);
 641
 642 struct kobject *get_disk(struct gendisk *disk)
 643 {
 644         struct module *owner;
 645         struct kobject *kobj;
 646
 647         if (!disk->fops)
 648                 return NULL;
 649         owner = disk->fops->owner;
 650         if (owner && !try_module_get(owner))
 651                 return NULL;
 652         kobj = kobject_get(&disk->kobj);
 653         if (kobj == NULL) {
 654                 module_put(owner);
 655                 return NULL;
 656         }
 657         return kobj;
 658
 659 }
 660
 661 EXPORT_SYMBOL(get_disk);
 662
 663 void put_disk(struct gendisk *disk)
 664 {
 665         if (disk)
 666                 kobject_put(&disk->kobj);
 667 }
 668
 669 EXPORT_SYMBOL(put_disk);
 670
 671 void set_device_ro(struct block_device *bdev, int flag)
 672 {
 673         if (bdev->bd_contains != bdev)
 674                 bdev->bd_part->policy = flag;
 675         else
 676                 bdev->bd_disk->policy = flag;
 677 }
 678
 679 EXPORT_SYMBOL(set_device_ro);
 680
 681 void set_disk_ro(struct gendisk *disk, int flag)
 682 {
 683         int i;
 684         disk->policy = flag;
 685         for (i = 0; i < disk->minors - 1; i++)
 686                 if (disk->part[i]) disk->part[i]->policy = flag;
 687 }
 688
 689 EXPORT_SYMBOL(set_disk_ro);
 690
 691 int bdev_read_only(struct block_device *bdev)
 692 {
 693         if (!bdev)
 694                 return 0;
 695         else if (bdev->bd_contains != bdev)
 696                 return bdev->bd_part->policy;
 697         else
 698                 return bdev->bd_disk->policy;
 699 }
 700
 701 EXPORT_SYMBOL(bdev_read_only);
 702
 703 int invalidate_partition(struct gendisk *disk, int index)
 704 {
 705         int res = 0;
 706         struct block_device *bdev = bdget_disk(disk, index);
 707         if (bdev) {
 708                 fsync_bdev(bdev);
 709                 res = __invalidate_device(bdev);
 710                 bdput(bdev);
 711         }
 712         return res;
 713 }
 714
 715 EXPORT_SYMBOL(invalidate_partition);