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