drivers/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
  19 #define MAX_PROBE_HASH 255      /* random */
  20
  21 static struct subsystem block_subsys;
  22
  23 static DECLARE_MUTEX(block_subsys_sem);
  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[MAX_PROBE_HASH];
  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 % MAX_PROBE_HASH;
  39 }
  40
  41 #ifdef CONFIG_PROC_FS
  42 /* get block device names in somewhat random order */
  43 int get_blkdev_list(char *p, int used)
  44 {
  45         struct blk_major_name *n;
  46         int i, len;
  47
  48         len = snprintf(p, (PAGE_SIZE-used), "\nBlock devices:\n");
  49
  50         down(&block_subsys_sem);
  51         for (i = 0; i < ARRAY_SIZE(major_names); i++) {
  52                 for (n = major_names[i]; n; n = n->next) {
  53                         /*
  54                          * If the curent string plus the 5 extra characters
  55                          * in the line would run us off the page, then we're done
  56                          */
  57                         if ((len + used + strlen(n->name) + 5) >= PAGE_SIZE)
  58                                 goto page_full;
  59                         len += sprintf(p+len, "%3d %s\n",
  60                                        n->major, n->name);
  61                 }
  62         }
  63 page_full:
  64         up(&block_subsys_sem);
  65
  66         return len;
  67 }
  68 #endif
  69
  70 int register_blkdev(unsigned int major, const char *name)
  71 {
  72         struct blk_major_name **n, *p;
  73         int index, ret = 0;
  74
  75         down(&block_subsys_sem);
  76
  77         /* temporary */
  78         if (major == 0) {
  79                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
  80                         if (major_names[index] == NULL)
  81                                 break;
  82                 }
  83
  84                 if (index == 0) {
  85                         printk("register_blkdev: failed to get major for %s\n",
  86                                name);
  87                         ret = -EBUSY;
  88                         goto out;
  89                 }
  90                 major = index;
  91                 ret = major;
  92         }
  93
  94         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
  95         if (p == NULL) {
  96                 ret = -ENOMEM;
  97                 goto out;
  98         }
  99
 100         p->major = major;
 101         strlcpy(p->name, name, sizeof(p->name));
 102         p->next = NULL;
 103         index = major_to_index(major);
 104
 105         for (n = &major_names[index]; *n; n = &(*n)->next) {
 106                 if ((*n)->major == major)
 107                         break;
 108         }
 109         if (!*n)
 110                 *n = p;
 111         else
 112                 ret = -EBUSY;
 113
 114         if (ret < 0) {
 115                 printk("register_blkdev: cannot get major %d for %s\n",
 116                        major, name);
 117                 kfree(p);
 118         }
 119 out:
 120         up(&block_subsys_sem);
 121         return ret;
 122 }
 123
 124 EXPORT_SYMBOL(register_blkdev);
 125
 126 /* todo: make void - error printk here */
 127 int unregister_blkdev(unsigned int major, const char *name)
 128 {
 129         struct blk_major_name **n;
 130         struct blk_major_name *p = NULL;
 131         int index = major_to_index(major);
 132         int ret = 0;
 133
 134         down(&block_subsys_sem);
 135         for (n = &major_names[index]; *n; n = &(*n)->next)
 136                 if ((*n)->major == major)
 137                         break;
 138         if (!*n || strcmp((*n)->name, name))
 139                 ret = -EINVAL;
 140         else {
 141                 p = *n;
 142                 *n = p->next;
 143         }
 144         up(&block_subsys_sem);
 145         kfree(p);
 146
 147         return ret;
 148 }
 149
 150 EXPORT_SYMBOL(unregister_blkdev);
 151
 152 static struct kobj_map *bdev_map;
 153
 154 /*
 155  * Register device numbers dev..(dev+range-1)
 156  * range must be nonzero
 157  * The hash chain is sorted on range, so that subranges can override.
 158  */
 159 void blk_register_region(dev_t dev, unsigned long range, struct module *module,
 160                          struct kobject *(*probe)(dev_t, int *, void *),
 161                          int (*lock)(dev_t, void *), void *data)
 162 {
 163         kobj_map(bdev_map, dev, range, module, probe, lock, data);
 164 }
 165
 166 EXPORT_SYMBOL(blk_register_region);
 167
 168 void blk_unregister_region(dev_t dev, unsigned long range)
 169 {
 170         kobj_unmap(bdev_map, dev, range);
 171 }
 172
 173 EXPORT_SYMBOL(blk_unregister_region);
 174
 175 static struct kobject *exact_match(dev_t dev, int *part, void *data)
 176 {
 177         struct gendisk *p = data;
 178         return &p->kobj;
 179 }
 180
 181 static int exact_lock(dev_t dev, void *data)
 182 {
 183         struct gendisk *p = data;
 184
 185         if (!get_disk(p))
 186                 return -1;
 187         return 0;
 188 }
 189
 190 /**
 191  * add_disk - add partitioning information to kernel list
 192  * @disk: per-device partitioning information
 193  *
 194  * This function registers the partitioning information in @disk
 195  * with the kernel.
 196  */
 197 void add_disk(struct gendisk *disk)
 198 {
 199         disk->flags |= GENHD_FL_UP;
 200         blk_register_region(MKDEV(disk->major, disk->first_minor),
 201                             disk->minors, NULL, exact_match, exact_lock, disk);
 202         register_disk(disk);
 203         blk_register_queue(disk);
 204 }
 205
 206 EXPORT_SYMBOL(add_disk);
 207 EXPORT_SYMBOL(del_gendisk);     /* in partitions/check.c */
 208
 209 void unlink_gendisk(struct gendisk *disk)
 210 {
 211         blk_unregister_queue(disk);
 212         blk_unregister_region(MKDEV(disk->major, disk->first_minor),
 213                               disk->minors);
 214 }
 215
 216 #define to_disk(obj) container_of(obj,struct gendisk,kobj)
 217
 218 /**
 219  * get_gendisk - get partitioning information for a given device
 220  * @dev: device to get partitioning information for
 221  *
 222  * This function gets the structure containing partitioning
 223  * information for the given device @dev.
 224  */
 225 struct gendisk *get_gendisk(dev_t dev, int *part)
 226 {
 227         struct kobject *kobj = kobj_lookup(bdev_map, dev, part);
 228         return  kobj ? to_disk(kobj) : NULL;
 229 }
 230
 231 #ifdef CONFIG_PROC_FS
 232 /* iterator */
 233 static void *part_start(struct seq_file *part, loff_t *pos)
 234 {
 235         struct list_head *p;
 236         loff_t l = *pos;
 237
 238         down(&block_subsys_sem);
 239         list_for_each(p, &block_subsys.kset.list)
 240                 if (!l--)
 241                         return list_entry(p, struct gendisk, kobj.entry);
 242         return NULL;
 243 }
 244
 245 static void *part_next(struct seq_file *part, void *v, loff_t *pos)
 246 {
 247         struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
 248         ++*pos;
 249         return p==&block_subsys.kset.list ? NULL :
 250                 list_entry(p, struct gendisk, kobj.entry);
 251 }
 252
 253 static void part_stop(struct seq_file *part, void *v)
 254 {
 255         up(&block_subsys_sem);
 256 }
 257
 258 static int show_partition(struct seq_file *part, void *v)
 259 {
 260         struct gendisk *sgp = v;
 261         int n;
 262         char buf[BDEVNAME_SIZE];
 263
 264         if (&sgp->kobj.entry == block_subsys.kset.list.next)
 265                 seq_puts(part, "major minor  #blocks  name\n\n");
 266
 267         /* Don't show non-partitionable removeable devices or empty devices */
 268         if (!get_capacity(sgp) ||
 269                         (sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
 270                 return 0;
 271         if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
 272                 return 0;
 273
 274         /* show the full disk and all non-0 size partitions of it */
 275         seq_printf(part, "%4d  %4d %10llu %s\n",
 276                 sgp->major, sgp->first_minor,
 277                 (unsigned long long)get_capacity(sgp) >> 1,
 278                 disk_name(sgp, 0, buf));
 279         for (n = 0; n < sgp->minors - 1; n++) {
 280                 if (!sgp->part[n])
 281                         continue;
 282                 if (sgp->part[n]->nr_sects == 0)
 283                         continue;
 284                 seq_printf(part, "%4d  %4d %10llu %s\n",
 285                         sgp->major, n + 1 + sgp->first_minor,
 286                         (unsigned long long)sgp->part[n]->nr_sects >> 1 ,
 287                         disk_name(sgp, n + 1, buf));
 288         }
 289
 290         return 0;
 291 }
 292
 293 struct seq_operations partitions_op = {
 294         .start =part_start,
 295         .next = part_next,
 296         .stop = part_stop,
 297         .show = show_partition
 298 };
 299 #endif
 300
 301
 302 extern int blk_dev_init(void);
 303
 304 static struct kobject *base_probe(dev_t dev, int *part, void *data)
 305 {
 306         if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
 307                 /* Make old-style 2.4 aliases work */
 308                 request_module("block-major-%d", MAJOR(dev));
 309         return NULL;
 310 }
 311
 312 static int __init genhd_device_init(void)
 313 {
 314         bdev_map = kobj_map_init(base_probe, &block_subsys_sem);
 315         blk_dev_init();
 316         subsystem_register(&block_subsys);
 317         return 0;
 318 }
 319
 320 subsys_initcall(genhd_device_init);
 321
 322
 323
 324 /*
 325  * kobject & sysfs bindings for block devices
 326  */
 327 static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
 328                               char *page)
 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 = -EIO;
 334
 335         if (disk_attr->show)
 336                 ret = disk_attr->show(disk,page);
 337         return ret;
 338 }
 339
 340 static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
 341                                const char *page, size_t count)
 342 {
 343         struct gendisk *disk = to_disk(kobj);
 344         struct disk_attribute *disk_attr =
 345                 container_of(attr,struct disk_attribute,attr);
 346         ssize_t ret = 0;
 347
 348         if (disk_attr->store)
 349                 ret = disk_attr->store(disk, page, count);
 350         return ret;
 351 }
 352
 353 static struct sysfs_ops disk_sysfs_ops = {
 354         .show   = &disk_attr_show,
 355         .store  = &disk_attr_store,
 356 };
 357
 358 static ssize_t disk_uevent_store(struct gendisk * disk,
 359                                  const char *buf, size_t count)
 360 {
 361         kobject_hotplug(&disk->kobj, KOBJ_ADD);
 362         return count;
 363 }
 364 static ssize_t disk_dev_read(struct gendisk * disk, char *page)
 365 {
 366         dev_t base = MKDEV(disk->major, disk->first_minor);
 367         return print_dev_t(page, base);
 368 }
 369 static ssize_t disk_range_read(struct gendisk * disk, char *page)
 370 {
 371         return sprintf(page, "%d\n", disk->minors);
 372 }
 373 static ssize_t disk_removable_read(struct gendisk * disk, char *page)
 374 {
 375         return sprintf(page, "%d\n",
 376                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 377
 378 }
 379 static ssize_t disk_size_read(struct gendisk * disk, char *page)
 380 {
 381         return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk));
 382 }
 383
 384 static ssize_t disk_stats_read(struct gendisk * disk, char *page)
 385 {
 386         preempt_disable();
 387         disk_round_stats(disk);
 388         preempt_enable();
 389         return sprintf(page,
 390                 "%8u %8u %8llu %8u "
 391                 "%8u %8u %8llu %8u "
 392                 "%8u %8u %8u"
 393                 "\n",
 394                 disk_stat_read(disk, reads), disk_stat_read(disk, read_merges),
 395                 (unsigned long long)disk_stat_read(disk, read_sectors),
 396                 jiffies_to_msecs(disk_stat_read(disk, read_ticks)),
 397                 disk_stat_read(disk, writes),
 398                 disk_stat_read(disk, write_merges),
 399                 (unsigned long long)disk_stat_read(disk, write_sectors),
 400                 jiffies_to_msecs(disk_stat_read(disk, write_ticks)),
 401                 disk->in_flight,
 402                 jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
 403                 jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
 404 }
 405 static struct disk_attribute disk_attr_uevent = {
 406         .attr = {.name = "uevent", .mode = S_IWUSR },
 407         .store  = disk_uevent_store
 408 };
 409 static struct disk_attribute disk_attr_dev = {
 410         .attr = {.name = "dev", .mode = S_IRUGO },
 411         .show   = disk_dev_read
 412 };
 413 static struct disk_attribute disk_attr_range = {
 414         .attr = {.name = "range", .mode = S_IRUGO },
 415         .show   = disk_range_read
 416 };
 417 static struct disk_attribute disk_attr_removable = {
 418         .attr = {.name = "removable", .mode = S_IRUGO },
 419         .show   = disk_removable_read
 420 };
 421 static struct disk_attribute disk_attr_size = {
 422         .attr = {.name = "size", .mode = S_IRUGO },
 423         .show   = disk_size_read
 424 };
 425 static struct disk_attribute disk_attr_stat = {
 426         .attr = {.name = "stat", .mode = S_IRUGO },
 427         .show   = disk_stats_read
 428 };
 429
 430 static struct attribute * default_attrs[] = {
 431         &disk_attr_uevent.attr,
 432         &disk_attr_dev.attr,
 433         &disk_attr_range.attr,
 434         &disk_attr_removable.attr,
 435         &disk_attr_size.attr,
 436         &disk_attr_stat.attr,
 437         NULL,
 438 };
 439
 440 static void disk_release(struct kobject * kobj)
 441 {
 442         struct gendisk *disk = to_disk(kobj);
 443         kfree(disk->random);
 444         kfree(disk->part);
 445         free_disk_stats(disk);
 446         kfree(disk);
 447 }
 448
 449 static struct kobj_type ktype_block = {
 450         .release        = disk_release,
 451         .sysfs_ops      = &disk_sysfs_ops,
 452         .default_attrs  = default_attrs,
 453 };
 454
 455 extern struct kobj_type ktype_part;
 456
 457 static int block_hotplug_filter(struct kset *kset, struct kobject *kobj)
 458 {
 459         struct kobj_type *ktype = get_ktype(kobj);
 460
 461         return ((ktype == &ktype_block) || (ktype == &ktype_part));
 462 }
 463
 464 static int block_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
 465                          int num_envp, char *buffer, int buffer_size)
 466 {
 467         struct kobj_type *ktype = get_ktype(kobj);
 468         struct device *physdev;
 469         struct gendisk *disk;
 470         struct hd_struct *part;
 471         int length = 0;
 472         int i = 0;
 473
 474         if (ktype == &ktype_block) {
 475                 disk = container_of(kobj, struct gendisk, kobj);
 476                 add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size,
 477                                     &length, "MINOR=%u", disk->first_minor);
 478         } else if (ktype == &ktype_part) {
 479                 disk = container_of(kobj->parent, struct gendisk, kobj);
 480                 part = container_of(kobj, struct hd_struct, kobj);
 481                 add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size,
 482                                     &length, "MINOR=%u",
 483                                     disk->first_minor + part->partno);
 484         } else
 485                 return 0;
 486
 487         add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size, &length,
 488                             "MAJOR=%u", disk->major);
 489
 490         /* add physical device, backing this device  */
 491         physdev = disk->driverfs_dev;
 492         if (physdev) {
 493                 char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL);
 494
 495                 add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size,
 496                                     &length, "PHYSDEVPATH=%s", path);
 497                 kfree(path);
 498
 499                 if (physdev->bus)
 500                         add_hotplug_env_var(envp, num_envp, &i,
 501                                             buffer, buffer_size, &length,
 502                                             "PHYSDEVBUS=%s",
 503                                             physdev->bus->name);
 504
 505                 if (physdev->driver)
 506                         add_hotplug_env_var(envp, num_envp, &i,
 507                                             buffer, buffer_size, &length,
 508                                             "PHYSDEVDRIVER=%s",
 509                                             physdev->driver->name);
 510         }
 511
 512         /* terminate, set to next free slot, shrink available space */
 513         envp[i] = NULL;
 514         envp = &envp[i];
 515         num_envp -= i;
 516         buffer = &buffer[length];
 517         buffer_size -= length;
 518
 519         return 0;
 520 }
 521
 522 static struct kset_hotplug_ops block_hotplug_ops = {
 523         .filter         = block_hotplug_filter,
 524         .hotplug        = block_hotplug,
 525 };
 526
 527 /* declare block_subsys. */
 528 static decl_subsys(block, &ktype_block, &block_hotplug_ops);
 529
 530
 531 /*
 532  * aggregate disk stat collector.  Uses the same stats that the sysfs
 533  * entries do, above, but makes them available through one seq_file.
 534  * Watching a few disks may be efficient through sysfs, but watching
 535  * all of them will be more efficient through this interface.
 536  *
 537  * The output looks suspiciously like /proc/partitions with a bunch of
 538  * extra fields.
 539  */
 540
 541 /* iterator */
 542 static void *diskstats_start(struct seq_file *part, loff_t *pos)
 543 {
 544         loff_t k = *pos;
 545         struct list_head *p;
 546
 547         down(&block_subsys_sem);
 548         list_for_each(p, &block_subsys.kset.list)
 549                 if (!k--)
 550                         return list_entry(p, struct gendisk, kobj.entry);
 551         return NULL;
 552 }
 553
 554 static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
 555 {
 556         struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
 557         ++*pos;
 558         return p==&block_subsys.kset.list ? NULL :
 559                 list_entry(p, struct gendisk, kobj.entry);
 560 }
 561
 562 static void diskstats_stop(struct seq_file *part, void *v)
 563 {
 564         up(&block_subsys_sem);
 565 }
 566
 567 static int diskstats_show(struct seq_file *s, void *v)
 568 {
 569         struct gendisk *gp = v;
 570         char buf[BDEVNAME_SIZE];
 571         int n = 0;
 572
 573         /*
 574         if (&sgp->kobj.entry == block_subsys.kset.list.next)
 575                 seq_puts(s,     "major minor name"
 576                                 "     rio rmerge rsect ruse wio wmerge "
 577                                 "wsect wuse running use aveq"
 578                                 "\n\n");
 579         */
 580
 581         preempt_disable();
 582         disk_round_stats(gp);
 583         preempt_enable();
 584         seq_printf(s, "%4d %4d %s %u %u %llu %u %u %u %llu %u %u %u %u\n",
 585                 gp->major, n + gp->first_minor, disk_name(gp, n, buf),
 586                 disk_stat_read(gp, reads), disk_stat_read(gp, read_merges),
 587                 (unsigned long long)disk_stat_read(gp, read_sectors),
 588                 jiffies_to_msecs(disk_stat_read(gp, read_ticks)),
 589                 disk_stat_read(gp, writes), disk_stat_read(gp, write_merges),
 590                 (unsigned long long)disk_stat_read(gp, write_sectors),
 591                 jiffies_to_msecs(disk_stat_read(gp, write_ticks)),
 592                 gp->in_flight,
 593                 jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
 594                 jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
 595
 596         /* now show all non-0 size partitions of it */
 597         for (n = 0; n < gp->minors - 1; n++) {
 598                 struct hd_struct *hd = gp->part[n];
 599
 600                 if (hd && hd->nr_sects)
 601                         seq_printf(s, "%4d %4d %s %u %u %u %u\n",
 602                                 gp->major, n + gp->first_minor + 1,
 603                                 disk_name(gp, n + 1, buf),
 604                                 hd->reads, hd->read_sectors,
 605                                 hd->writes, hd->write_sectors);
 606         }
 607
 608         return 0;
 609 }
 610
 611 struct seq_operations diskstats_op = {
 612         .start  = diskstats_start,
 613         .next   = diskstats_next,
 614         .stop   = diskstats_stop,
 615         .show   = diskstats_show
 616 };
 617
 618 struct gendisk *alloc_disk(int minors)
 619 {
 620         return alloc_disk_node(minors, -1);
 621 }
 622
 623 struct gendisk *alloc_disk_node(int minors, int node_id)
 624 {
 625         struct gendisk *disk;
 626
 627         disk = kmalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
 628         if (disk) {
 629                 memset(disk, 0, sizeof(struct gendisk));
 630                 if (!init_disk_stats(disk)) {
 631                         kfree(disk);
 632                         return NULL;
 633                 }
 634                 if (minors > 1) {
 635                         int size = (minors - 1) * sizeof(struct hd_struct *);
 636                         disk->part = kmalloc_node(size, GFP_KERNEL, node_id);
 637                         if (!disk->part) {
 638                                 kfree(disk);
 639                                 return NULL;
 640                         }
 641                         memset(disk->part, 0, size);
 642                 }
 643                 disk->minors = minors;
 644                 kobj_set_kset_s(disk,block_subsys);
 645                 kobject_init(&disk->kobj);
 646                 rand_initialize_disk(disk);
 647         }
 648         return disk;
 649 }
 650
 651 EXPORT_SYMBOL(alloc_disk);
 652 EXPORT_SYMBOL(alloc_disk_node);
 653
 654 struct kobject *get_disk(struct gendisk *disk)
 655 {
 656         struct module *owner;
 657         struct kobject *kobj;
 658
 659         if (!disk->fops)
 660                 return NULL;
 661         owner = disk->fops->owner;
 662         if (owner && !try_module_get(owner))
 663                 return NULL;
 664         kobj = kobject_get(&disk->kobj);
 665         if (kobj == NULL) {
 666                 module_put(owner);
 667                 return NULL;
 668         }
 669         return kobj;
 670
 671 }
 672
 673 EXPORT_SYMBOL(get_disk);
 674
 675 void put_disk(struct gendisk *disk)
 676 {
 677         if (disk)
 678                 kobject_put(&disk->kobj);
 679 }
 680
 681 EXPORT_SYMBOL(put_disk);
 682
 683 void set_device_ro(struct block_device *bdev, int flag)
 684 {
 685         if (bdev->bd_contains != bdev)
 686                 bdev->bd_part->policy = flag;
 687         else
 688                 bdev->bd_disk->policy = flag;
 689 }
 690
 691 EXPORT_SYMBOL(set_device_ro);
 692
 693 void set_disk_ro(struct gendisk *disk, int flag)
 694 {
 695         int i;
 696         disk->policy = flag;
 697         for (i = 0; i < disk->minors - 1; i++)
 698                 if (disk->part[i]) disk->part[i]->policy = flag;
 699 }
 700
 701 EXPORT_SYMBOL(set_disk_ro);
 702
 703 int bdev_read_only(struct block_device *bdev)
 704 {
 705         if (!bdev)
 706                 return 0;
 707         else if (bdev->bd_contains != bdev)
 708                 return bdev->bd_part->policy;
 709         else
 710                 return bdev->bd_disk->policy;
 711 }
 712
 713 EXPORT_SYMBOL(bdev_read_only);
 714
 715 int invalidate_partition(struct gendisk *disk, int index)
 716 {
 717         int res = 0;
 718         struct block_device *bdev = bdget_disk(disk, index);
 719         if (bdev) {
 720                 fsync_bdev(bdev);
 721                 res = __invalidate_device(bdev);
 722                 bdput(bdev);
 723         }
 724         return res;
 725 }
 726
 727 EXPORT_SYMBOL(invalidate_partition);