block/partitions/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 1991-1998  Linus Torvalds
   4  * Re-organised Feb 1998 Russell King
   5  * Copyright (C) 2020 Christoph Hellwig
   6  */
   7 #include <linux/fs.h>
   8 #include <linux/major.h>
   9 #include <linux/slab.h>
  10 #include <linux/ctype.h>
  11 #include <linux/genhd.h>
  12 #include <linux/vmalloc.h>
  13 #include <linux/blktrace_api.h>
  14 #include <linux/raid/detect.h>
  15 #include "check.h"
  16
  17 static int (*check_part[])(struct parsed_partitions *) = {
  18         /*
  19          * Probe partition formats with tables at disk address 0
  20          * that also have an ADFS boot block at 0xdc0.
  21          */
  22 #ifdef CONFIG_ACORN_PARTITION_ICS
  23         adfspart_check_ICS,
  24 #endif
  25 #ifdef CONFIG_ACORN_PARTITION_POWERTEC
  26         adfspart_check_POWERTEC,
  27 #endif
  28 #ifdef CONFIG_ACORN_PARTITION_EESOX
  29         adfspart_check_EESOX,
  30 #endif
  31
  32         /*
  33          * Now move on to formats that only have partition info at
  34          * disk address 0xdc0.  Since these may also have stale
  35          * PC/BIOS partition tables, they need to come before
  36          * the msdos entry.
  37          */
  38 #ifdef CONFIG_ACORN_PARTITION_CUMANA
  39         adfspart_check_CUMANA,
  40 #endif
  41 #ifdef CONFIG_ACORN_PARTITION_ADFS
  42         adfspart_check_ADFS,
  43 #endif
  44
  45 #ifdef CONFIG_CMDLINE_PARTITION
  46         cmdline_partition,
  47 #endif
  48 #ifdef CONFIG_EFI_PARTITION
  49         efi_partition,          /* this must come before msdos */
  50 #endif
  51 #ifdef CONFIG_SGI_PARTITION
  52         sgi_partition,
  53 #endif
  54 #ifdef CONFIG_LDM_PARTITION
  55         ldm_partition,          /* this must come before msdos */
  56 #endif
  57 #ifdef CONFIG_MSDOS_PARTITION
  58         msdos_partition,
  59 #endif
  60 #ifdef CONFIG_OSF_PARTITION
  61         osf_partition,
  62 #endif
  63 #ifdef CONFIG_SUN_PARTITION
  64         sun_partition,
  65 #endif
  66 #ifdef CONFIG_AMIGA_PARTITION
  67         amiga_partition,
  68 #endif
  69 #ifdef CONFIG_ATARI_PARTITION
  70         atari_partition,
  71 #endif
  72 #ifdef CONFIG_MAC_PARTITION
  73         mac_partition,
  74 #endif
  75 #ifdef CONFIG_ULTRIX_PARTITION
  76         ultrix_partition,
  77 #endif
  78 #ifdef CONFIG_IBM_PARTITION
  79         ibm_partition,
  80 #endif
  81 #ifdef CONFIG_KARMA_PARTITION
  82         karma_partition,
  83 #endif
  84 #ifdef CONFIG_SYSV68_PARTITION
  85         sysv68_partition,
  86 #endif
  87         NULL
  88 };
  89
  90 static void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors)
  91 {
  92         spin_lock(&bdev->bd_size_lock);
  93         i_size_write(bdev->bd_inode, (loff_t)sectors << SECTOR_SHIFT);
  94         spin_unlock(&bdev->bd_size_lock);
  95 }
  96
  97 static struct parsed_partitions *allocate_partitions(struct gendisk *hd)
  98 {
  99         struct parsed_partitions *state;
 100         int nr;
 101
 102         state = kzalloc(sizeof(*state), GFP_KERNEL);
 103         if (!state)
 104                 return NULL;
 105
 106         nr = disk_max_parts(hd);
 107         state->parts = vzalloc(array_size(nr, sizeof(state->parts[0])));
 108         if (!state->parts) {
 109                 kfree(state);
 110                 return NULL;
 111         }
 112
 113         state->limit = nr;
 114
 115         return state;
 116 }
 117
 118 static void free_partitions(struct parsed_partitions *state)
 119 {
 120         vfree(state->parts);
 121         kfree(state);
 122 }
 123
 124 static struct parsed_partitions *check_partition(struct gendisk *hd)
 125 {
 126         struct parsed_partitions *state;
 127         int i, res, err;
 128
 129         state = allocate_partitions(hd);
 130         if (!state)
 131                 return NULL;
 132         state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
 133         if (!state->pp_buf) {
 134                 free_partitions(state);
 135                 return NULL;
 136         }
 137         state->pp_buf[0] = '\0';
 138
 139         state->disk = hd;
 140         snprintf(state->name, BDEVNAME_SIZE, "%s", hd->disk_name);
 141         snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
 142         if (isdigit(state->name[strlen(state->name)-1]))
 143                 sprintf(state->name, "p");
 144
 145         i = res = err = 0;
 146         while (!res && check_part[i]) {
 147                 memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
 148                 res = check_part[i++](state);
 149                 if (res < 0) {
 150                         /*
 151                          * We have hit an I/O error which we don't report now.
 152                          * But record it, and let the others do their job.
 153                          */
 154                         err = res;
 155                         res = 0;
 156                 }
 157
 158         }
 159         if (res > 0) {
 160                 printk(KERN_INFO "%s", state->pp_buf);
 161
 162                 free_page((unsigned long)state->pp_buf);
 163                 return state;
 164         }
 165         if (state->access_beyond_eod)
 166                 err = -ENOSPC;
 167         /*
 168          * The partition is unrecognized. So report I/O errors if there were any
 169          */
 170         if (err)
 171                 res = err;
 172         if (res) {
 173                 strlcat(state->pp_buf,
 174                         " unable to read partition table\n", PAGE_SIZE);
 175                 printk(KERN_INFO "%s", state->pp_buf);
 176         }
 177
 178         free_page((unsigned long)state->pp_buf);
 179         free_partitions(state);
 180         return ERR_PTR(res);
 181 }
 182
 183 static ssize_t part_partition_show(struct device *dev,
 184                                    struct device_attribute *attr, char *buf)
 185 {
 186         return sprintf(buf, "%d\n", dev_to_bdev(dev)->bd_partno);
 187 }
 188
 189 static ssize_t part_start_show(struct device *dev,
 190                                struct device_attribute *attr, char *buf)
 191 {
 192         return sprintf(buf, "%llu\n", dev_to_bdev(dev)->bd_start_sect);
 193 }
 194
 195 static ssize_t part_ro_show(struct device *dev,
 196                             struct device_attribute *attr, char *buf)
 197 {
 198         return sprintf(buf, "%d\n", bdev_read_only(dev_to_bdev(dev)));
 199 }
 200
 201 static ssize_t part_alignment_offset_show(struct device *dev,
 202                                           struct device_attribute *attr, char *buf)
 203 {
 204         struct block_device *bdev = dev_to_bdev(dev);
 205
 206         return sprintf(buf, "%u\n",
 207                 queue_limit_alignment_offset(&bdev->bd_disk->queue->limits,
 208                                 bdev->bd_start_sect));
 209 }
 210
 211 static ssize_t part_discard_alignment_show(struct device *dev,
 212                                            struct device_attribute *attr, char *buf)
 213 {
 214         struct block_device *bdev = dev_to_bdev(dev);
 215
 216         return sprintf(buf, "%u\n",
 217                 queue_limit_discard_alignment(&bdev->bd_disk->queue->limits,
 218                                 bdev->bd_start_sect));
 219 }
 220
 221 static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
 222 static DEVICE_ATTR(start, 0444, part_start_show, NULL);
 223 static DEVICE_ATTR(size, 0444, part_size_show, NULL);
 224 static DEVICE_ATTR(ro, 0444, part_ro_show, NULL);
 225 static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
 226 static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
 227 static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
 228 static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
 229 #ifdef CONFIG_FAIL_MAKE_REQUEST
 230 static struct device_attribute dev_attr_fail =
 231         __ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
 232 #endif
 233
 234 static struct attribute *part_attrs[] = {
 235         &dev_attr_partition.attr,
 236         &dev_attr_start.attr,
 237         &dev_attr_size.attr,
 238         &dev_attr_ro.attr,
 239         &dev_attr_alignment_offset.attr,
 240         &dev_attr_discard_alignment.attr,
 241         &dev_attr_stat.attr,
 242         &dev_attr_inflight.attr,
 243 #ifdef CONFIG_FAIL_MAKE_REQUEST
 244         &dev_attr_fail.attr,
 245 #endif
 246         NULL
 247 };
 248
 249 static struct attribute_group part_attr_group = {
 250         .attrs = part_attrs,
 251 };
 252
 253 static const struct attribute_group *part_attr_groups[] = {
 254         &part_attr_group,
 255 #ifdef CONFIG_BLK_DEV_IO_TRACE
 256         &blk_trace_attr_group,
 257 #endif
 258         NULL
 259 };
 260
 261 static void part_release(struct device *dev)
 262 {
 263         put_disk(dev_to_bdev(dev)->bd_disk);
 264         iput(dev_to_bdev(dev)->bd_inode);
 265 }
 266
 267 static int part_uevent(struct device *dev, struct kobj_uevent_env *env)
 268 {
 269         struct block_device *part = dev_to_bdev(dev);
 270
 271         add_uevent_var(env, "PARTN=%u", part->bd_partno);
 272         if (part->bd_meta_info && part->bd_meta_info->volname[0])
 273                 add_uevent_var(env, "PARTNAME=%s", part->bd_meta_info->volname);
 274         return 0;
 275 }
 276
 277 struct device_type part_type = {
 278         .name           = "partition",
 279         .groups         = part_attr_groups,
 280         .release        = part_release,
 281         .uevent         = part_uevent,
 282 };
 283
 284 static void delete_partition(struct block_device *part)
 285 {
 286         lockdep_assert_held(&part->bd_disk->open_mutex);
 287
 288         fsync_bdev(part);
 289         __invalidate_device(part, true);
 290
 291         xa_erase(&part->bd_disk->part_tbl, part->bd_partno);
 292         kobject_put(part->bd_holder_dir);
 293         device_del(&part->bd_device);
 294
 295         /*
 296          * Remove the block device from the inode hash, so that it cannot be
 297          * looked up any more even when openers still hold references.
 298          */
 299         remove_inode_hash(part->bd_inode);
 300
 301         put_device(&part->bd_device);
 302 }
 303
 304 static ssize_t whole_disk_show(struct device *dev,
 305                                struct device_attribute *attr, char *buf)
 306 {
 307         return 0;
 308 }
 309 static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
 310
 311 /*
 312  * Must be called either with open_mutex held, before a disk can be opened or
 313  * after all disk users are gone.
 314  */
 315 static struct block_device *add_partition(struct gendisk *disk, int partno,
 316                                 sector_t start, sector_t len, int flags,
 317                                 struct partition_meta_info *info)
 318 {
 319         dev_t devt = MKDEV(0, 0);
 320         struct device *ddev = disk_to_dev(disk);
 321         struct device *pdev;
 322         struct block_device *bdev;
 323         const char *dname;
 324         int err;
 325
 326         lockdep_assert_held(&disk->open_mutex);
 327
 328         if (partno >= disk_max_parts(disk))
 329                 return ERR_PTR(-EINVAL);
 330
 331         /*
 332          * Partitions are not supported on zoned block devices that are used as
 333          * such.
 334          */
 335         switch (disk->queue->limits.zoned) {
 336         case BLK_ZONED_HM:
 337                 pr_warn("%s: partitions not supported on host managed zoned block device\n",
 338                         disk->disk_name);
 339                 return ERR_PTR(-ENXIO);
 340         case BLK_ZONED_HA:
 341                 pr_info("%s: disabling host aware zoned block device support due to partitions\n",
 342                         disk->disk_name);
 343                 blk_queue_set_zoned(disk, BLK_ZONED_NONE);
 344                 break;
 345         case BLK_ZONED_NONE:
 346                 break;
 347         }
 348
 349         if (xa_load(&disk->part_tbl, partno))
 350                 return ERR_PTR(-EBUSY);
 351
 352         /* ensure we always have a reference to the whole disk */
 353         get_device(disk_to_dev(disk));
 354
 355         err = -ENOMEM;
 356         bdev = bdev_alloc(disk, partno);
 357         if (!bdev)
 358                 goto out_put_disk;
 359
 360         bdev->bd_start_sect = start;
 361         bdev_set_nr_sectors(bdev, len);
 362
 363         pdev = &bdev->bd_device;
 364         dname = dev_name(ddev);
 365         if (isdigit(dname[strlen(dname) - 1]))
 366                 dev_set_name(pdev, "%sp%d", dname, partno);
 367         else
 368                 dev_set_name(pdev, "%s%d", dname, partno);
 369
 370         device_initialize(pdev);
 371         pdev->class = &block_class;
 372         pdev->type = &part_type;
 373         pdev->parent = ddev;
 374
 375         /* in consecutive minor range? */
 376         if (bdev->bd_partno < disk->minors) {
 377                 devt = MKDEV(disk->major, disk->first_minor + bdev->bd_partno);
 378         } else {
 379                 err = blk_alloc_ext_minor();
 380                 if (err < 0)
 381                         goto out_put;
 382                 devt = MKDEV(BLOCK_EXT_MAJOR, err);
 383         }
 384         pdev->devt = devt;
 385
 386         if (info) {
 387                 err = -ENOMEM;
 388                 bdev->bd_meta_info = kmemdup(info, sizeof(*info), GFP_KERNEL);
 389                 if (!bdev->bd_meta_info)
 390                         goto out_put;
 391         }
 392
 393         /* delay uevent until 'holders' subdir is created */
 394         dev_set_uevent_suppress(pdev, 1);
 395         err = device_add(pdev);
 396         if (err)
 397                 goto out_put;
 398
 399         err = -ENOMEM;
 400         bdev->bd_holder_dir = kobject_create_and_add("holders", &pdev->kobj);
 401         if (!bdev->bd_holder_dir)
 402                 goto out_del;
 403
 404         dev_set_uevent_suppress(pdev, 0);
 405         if (flags & ADDPART_FLAG_WHOLEDISK) {
 406                 err = device_create_file(pdev, &dev_attr_whole_disk);
 407                 if (err)
 408                         goto out_del;
 409         }
 410
 411         /* everything is up and running, commence */
 412         err = xa_insert(&disk->part_tbl, partno, bdev, GFP_KERNEL);
 413         if (err)
 414                 goto out_del;
 415         bdev_add(bdev, devt);
 416
 417         /* suppress uevent if the disk suppresses it */
 418         if (!dev_get_uevent_suppress(ddev))
 419                 kobject_uevent(&pdev->kobj, KOBJ_ADD);
 420         return bdev;
 421
 422 out_del:
 423         kobject_put(bdev->bd_holder_dir);
 424         device_del(pdev);
 425 out_put:
 426         put_device(pdev);
 427         return ERR_PTR(err);
 428 out_put_disk:
 429         put_disk(disk);
 430         return ERR_PTR(err);
 431 }
 432
 433 static bool partition_overlaps(struct gendisk *disk, sector_t start,
 434                 sector_t length, int skip_partno)
 435 {
 436         struct block_device *part;
 437         bool overlap = false;
 438         unsigned long idx;
 439
 440         rcu_read_lock();
 441         xa_for_each_start(&disk->part_tbl, idx, part, 1) {
 442                 if (part->bd_partno != skip_partno &&
 443                     start < part->bd_start_sect + bdev_nr_sectors(part) &&
 444                     start + length > part->bd_start_sect) {
 445                         overlap = true;
 446                         break;
 447                 }
 448         }
 449         rcu_read_unlock();
 450
 451         return overlap;
 452 }
 453
 454 int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
 455                 sector_t length)
 456 {
 457         struct block_device *part;
 458         int ret;
 459
 460         mutex_lock(&disk->open_mutex);
 461         if (!disk_live(disk)) {
 462                 ret = -ENXIO;
 463                 goto out;
 464         }
 465
 466         if (partition_overlaps(disk, start, length, -1)) {
 467                 ret = -EBUSY;
 468                 goto out;
 469         }
 470
 471         part = add_partition(disk, partno, start, length,
 472                         ADDPART_FLAG_NONE, NULL);
 473         ret = PTR_ERR_OR_ZERO(part);
 474 out:
 475         mutex_unlock(&disk->open_mutex);
 476         return ret;
 477 }
 478
 479 int bdev_del_partition(struct gendisk *disk, int partno)
 480 {
 481         struct block_device *part = NULL;
 482         int ret = -ENXIO;
 483
 484         mutex_lock(&disk->open_mutex);
 485         part = xa_load(&disk->part_tbl, partno);
 486         if (!part)
 487                 goto out_unlock;
 488
 489         ret = -EBUSY;
 490         if (part->bd_openers)
 491                 goto out_unlock;
 492
 493         delete_partition(part);
 494         ret = 0;
 495 out_unlock:
 496         mutex_unlock(&disk->open_mutex);
 497         return ret;
 498 }
 499
 500 int bdev_resize_partition(struct gendisk *disk, int partno, sector_t start,
 501                 sector_t length)
 502 {
 503         struct block_device *part = NULL;
 504         int ret = -ENXIO;
 505
 506         mutex_lock(&disk->open_mutex);
 507         part = xa_load(&disk->part_tbl, partno);
 508         if (!part)
 509                 goto out_unlock;
 510
 511         ret = -EINVAL;
 512         if (start != part->bd_start_sect)
 513                 goto out_unlock;
 514
 515         ret = -EBUSY;
 516         if (partition_overlaps(disk, start, length, partno))
 517                 goto out_unlock;
 518
 519         bdev_set_nr_sectors(part, length);
 520
 521         ret = 0;
 522 out_unlock:
 523         mutex_unlock(&disk->open_mutex);
 524         return ret;
 525 }
 526
 527 static bool disk_unlock_native_capacity(struct gendisk *disk)
 528 {
 529         const struct block_device_operations *bdops = disk->fops;
 530
 531         if (bdops->unlock_native_capacity &&
 532             !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) {
 533                 printk(KERN_CONT "enabling native capacity\n");
 534                 bdops->unlock_native_capacity(disk);
 535                 disk->flags |= GENHD_FL_NATIVE_CAPACITY;
 536                 return true;
 537         } else {
 538                 printk(KERN_CONT "truncated\n");
 539                 return false;
 540         }
 541 }
 542
 543 void blk_drop_partitions(struct gendisk *disk)
 544 {
 545         struct block_device *part;
 546         unsigned long idx;
 547
 548         lockdep_assert_held(&disk->open_mutex);
 549
 550         xa_for_each_start(&disk->part_tbl, idx, part, 1)
 551                 delete_partition(part);
 552 }
 553
 554 static bool blk_add_partition(struct gendisk *disk,
 555                 struct parsed_partitions *state, int p)
 556 {
 557         sector_t size = state->parts[p].size;
 558         sector_t from = state->parts[p].from;
 559         struct block_device *part;
 560
 561         if (!size)
 562                 return true;
 563
 564         if (from >= get_capacity(disk)) {
 565                 printk(KERN_WARNING
 566                        "%s: p%d start %llu is beyond EOD, ",
 567                        disk->disk_name, p, (unsigned long long) from);
 568                 if (disk_unlock_native_capacity(disk))
 569                         return false;
 570                 return true;
 571         }
 572
 573         if (from + size > get_capacity(disk)) {
 574                 printk(KERN_WARNING
 575                        "%s: p%d size %llu extends beyond EOD, ",
 576                        disk->disk_name, p, (unsigned long long) size);
 577
 578                 if (disk_unlock_native_capacity(disk))
 579                         return false;
 580
 581                 /*
 582                  * We can not ignore partitions of broken tables created by for
 583                  * example camera firmware, but we limit them to the end of the
 584                  * disk to avoid creating invalid block devices.
 585                  */
 586                 size = get_capacity(disk) - from;
 587         }
 588
 589         part = add_partition(disk, p, from, size, state->parts[p].flags,
 590                              &state->parts[p].info);
 591         if (IS_ERR(part) && PTR_ERR(part) != -ENXIO) {
 592                 printk(KERN_ERR " %s: p%d could not be added: %ld\n",
 593                        disk->disk_name, p, -PTR_ERR(part));
 594                 return true;
 595         }
 596
 597         if (IS_BUILTIN(CONFIG_BLK_DEV_MD) &&
 598             (state->parts[p].flags & ADDPART_FLAG_RAID))
 599                 md_autodetect_dev(part->bd_dev);
 600
 601         return true;
 602 }
 603
 604 static int blk_add_partitions(struct gendisk *disk)
 605 {
 606         struct parsed_partitions *state;
 607         int ret = -EAGAIN, p;
 608
 609         if (!disk_part_scan_enabled(disk))
 610                 return 0;
 611
 612         state = check_partition(disk);
 613         if (!state)
 614                 return 0;
 615         if (IS_ERR(state)) {
 616                 /*
 617                  * I/O error reading the partition table.  If we tried to read
 618                  * beyond EOD, retry after unlocking the native capacity.
 619                  */
 620                 if (PTR_ERR(state) == -ENOSPC) {
 621                         printk(KERN_WARNING "%s: partition table beyond EOD, ",
 622                                disk->disk_name);
 623                         if (disk_unlock_native_capacity(disk))
 624                                 return -EAGAIN;
 625                 }
 626                 return -EIO;
 627         }
 628
 629         /*
 630          * Partitions are not supported on host managed zoned block devices.
 631          */
 632         if (disk->queue->limits.zoned == BLK_ZONED_HM) {
 633                 pr_warn("%s: ignoring partition table on host managed zoned block device\n",
 634                         disk->disk_name);
 635                 ret = 0;
 636                 goto out_free_state;
 637         }
 638
 639         /*
 640          * If we read beyond EOD, try unlocking native capacity even if the
 641          * partition table was successfully read as we could be missing some
 642          * partitions.
 643          */
 644         if (state->access_beyond_eod) {
 645                 printk(KERN_WARNING
 646                        "%s: partition table partially beyond EOD, ",
 647                        disk->disk_name);
 648                 if (disk_unlock_native_capacity(disk))
 649                         goto out_free_state;
 650         }
 651
 652         /* tell userspace that the media / partition table may have changed */
 653         kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
 654
 655         for (p = 1; p < state->limit; p++)
 656                 if (!blk_add_partition(disk, state, p))
 657                         goto out_free_state;
 658
 659         ret = 0;
 660 out_free_state:
 661         free_partitions(state);
 662         return ret;
 663 }
 664
 665 int bdev_disk_changed(struct gendisk *disk, bool invalidate)
 666 {
 667         int ret = 0;
 668
 669         lockdep_assert_held(&disk->open_mutex);
 670
 671         if (!disk_live(disk))
 672                 return -ENXIO;
 673
 674 rescan:
 675         if (disk->open_partitions)
 676                 return -EBUSY;
 677         sync_blockdev(disk->part0);
 678         invalidate_bdev(disk->part0);
 679         blk_drop_partitions(disk);
 680
 681         clear_bit(GD_NEED_PART_SCAN, &disk->state);
 682
 683         /*
 684          * Historically we only set the capacity to zero for devices that
 685          * support partitions (independ of actually having partitions created).
 686          * Doing that is rather inconsistent, but changing it broke legacy
 687          * udisks polling for legacy ide-cdrom devices.  Use the crude check
 688          * below to get the sane behavior for most device while not breaking
 689          * userspace for this particular setup.
 690          */
 691         if (invalidate) {
 692                 if (disk_part_scan_enabled(disk) ||
 693                     !(disk->flags & GENHD_FL_REMOVABLE))
 694                         set_capacity(disk, 0);
 695         }
 696
 697         if (get_capacity(disk)) {
 698                 ret = blk_add_partitions(disk);
 699                 if (ret == -EAGAIN)
 700                         goto rescan;
 701         } else if (invalidate) {
 702                 /*
 703                  * Tell userspace that the media / partition table may have
 704                  * changed.
 705                  */
 706                 kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
 707         }
 708
 709         return ret;
 710 }
 711 /*
 712  * Only exported for loop and dasd for historic reasons.  Don't use in new
 713  * code!
 714  */
 715 EXPORT_SYMBOL_GPL(bdev_disk_changed);
 716
 717 void *read_part_sector(struct parsed_partitions *state, sector_t n, Sector *p)
 718 {
 719         struct address_space *mapping = state->disk->part0->bd_inode->i_mapping;
 720         struct page *page;
 721
 722         if (n >= get_capacity(state->disk)) {
 723                 state->access_beyond_eod = true;
 724                 return NULL;
 725         }
 726
 727         page = read_mapping_page(mapping,
 728                         (pgoff_t)(n >> (PAGE_SHIFT - 9)), NULL);
 729         if (IS_ERR(page))
 730                 goto out;
 731         if (PageError(page))
 732                 goto out_put_page;
 733
 734         p->v = page;
 735         return (unsigned char *)page_address(page) +
 736                         ((n & ((1 << (PAGE_SHIFT - 9)) - 1)) << SECTOR_SHIFT);
 737 out_put_page:
 738         put_page(page);
 739 out:
 740         p->v = NULL;
 741         return NULL;
 742 }