xref: /openbmc/linux/block/partitions/core.c (revision 80f5bfbb)
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_EFI_PARTITION
47 	efi_partition,		/* this must come before msdos */
48 #endif
49 #ifdef CONFIG_SGI_PARTITION
50 	sgi_partition,
51 #endif
52 #ifdef CONFIG_LDM_PARTITION
53 	ldm_partition,		/* this must come before msdos */
54 #endif
55 #ifdef CONFIG_MSDOS_PARTITION
56 	msdos_partition,
57 #endif
58 #ifdef CONFIG_OSF_PARTITION
59 	osf_partition,
60 #endif
61 #ifdef CONFIG_SUN_PARTITION
62 	sun_partition,
63 #endif
64 #ifdef CONFIG_AMIGA_PARTITION
65 	amiga_partition,
66 #endif
67 #ifdef CONFIG_ATARI_PARTITION
68 	atari_partition,
69 #endif
70 #ifdef CONFIG_MAC_PARTITION
71 	mac_partition,
72 #endif
73 #ifdef CONFIG_ULTRIX_PARTITION
74 	ultrix_partition,
75 #endif
76 #ifdef CONFIG_IBM_PARTITION
77 	ibm_partition,
78 #endif
79 #ifdef CONFIG_KARMA_PARTITION
80 	karma_partition,
81 #endif
82 #ifdef CONFIG_SYSV68_PARTITION
83 	sysv68_partition,
84 #endif
85 	NULL
86 };
87 
allocate_partitions(struct gendisk * hd)88 static struct parsed_partitions *allocate_partitions(struct gendisk *hd)
89 {
90 	struct parsed_partitions *state;
91 	int nr = DISK_MAX_PARTS;
92 
93 	state = kzalloc(sizeof(*state), GFP_KERNEL);
94 	if (!state)
95 		return NULL;
96 
97 	state->parts = vzalloc(array_size(nr, sizeof(state->parts[0])));
98 	if (!state->parts) {
99 		kfree(state);
100 		return NULL;
101 	}
102 
103 	state->limit = nr;
104 
105 	return state;
106 }
107 
free_partitions(struct parsed_partitions * state)108 static void free_partitions(struct parsed_partitions *state)
109 {
110 	vfree(state->parts);
111 	kfree(state);
112 }
113 
check_partition(struct gendisk * hd)114 static struct parsed_partitions *check_partition(struct gendisk *hd)
115 {
116 	struct parsed_partitions *state;
117 	int i, res, err;
118 
119 	state = allocate_partitions(hd);
120 	if (!state)
121 		return NULL;
122 	state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
123 	if (!state->pp_buf) {
124 		free_partitions(state);
125 		return NULL;
126 	}
127 	state->pp_buf[0] = '\0';
128 
129 	state->disk = hd;
130 	snprintf(state->name, BDEVNAME_SIZE, "%s", hd->disk_name);
131 	snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
132 	if (isdigit(state->name[strlen(state->name)-1]))
133 		sprintf(state->name, "p");
134 
135 	i = res = err = 0;
136 	while (!res && check_part[i]) {
137 		memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
138 		res = check_part[i++](state);
139 		if (res < 0) {
140 			/*
141 			 * We have hit an I/O error which we don't report now.
142 			 * But record it, and let the others do their job.
143 			 */
144 			err = res;
145 			res = 0;
146 		}
147 
148 	}
149 	if (res > 0) {
150 		printk(KERN_INFO "%s", state->pp_buf);
151 
152 		free_page((unsigned long)state->pp_buf);
153 		return state;
154 	}
155 	if (state->access_beyond_eod)
156 		err = -ENOSPC;
157 	/*
158 	 * The partition is unrecognized. So report I/O errors if there were any
159 	 */
160 	if (err)
161 		res = err;
162 	if (res) {
163 		strlcat(state->pp_buf,
164 			" unable to read partition table\n", PAGE_SIZE);
165 		printk(KERN_INFO "%s", state->pp_buf);
166 	}
167 
168 	free_page((unsigned long)state->pp_buf);
169 	free_partitions(state);
170 	return ERR_PTR(res);
171 }
172 
part_partition_show(struct device * dev,struct device_attribute * attr,char * buf)173 static ssize_t part_partition_show(struct device *dev,
174 				   struct device_attribute *attr, char *buf)
175 {
176 	return sprintf(buf, "%d\n", dev_to_bdev(dev)->bd_partno);
177 }
178 
part_start_show(struct device * dev,struct device_attribute * attr,char * buf)179 static ssize_t part_start_show(struct device *dev,
180 			       struct device_attribute *attr, char *buf)
181 {
182 	return sprintf(buf, "%llu\n", dev_to_bdev(dev)->bd_start_sect);
183 }
184 
part_ro_show(struct device * dev,struct device_attribute * attr,char * buf)185 static ssize_t part_ro_show(struct device *dev,
186 			    struct device_attribute *attr, char *buf)
187 {
188 	return sprintf(buf, "%d\n", bdev_read_only(dev_to_bdev(dev)));
189 }
190 
part_alignment_offset_show(struct device * dev,struct device_attribute * attr,char * buf)191 static ssize_t part_alignment_offset_show(struct device *dev,
192 					  struct device_attribute *attr, char *buf)
193 {
194 	return sprintf(buf, "%u\n", bdev_alignment_offset(dev_to_bdev(dev)));
195 }
196 
part_discard_alignment_show(struct device * dev,struct device_attribute * attr,char * buf)197 static ssize_t part_discard_alignment_show(struct device *dev,
198 					   struct device_attribute *attr, char *buf)
199 {
200 	return sprintf(buf, "%u\n", bdev_discard_alignment(dev_to_bdev(dev)));
201 }
202 
203 static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
204 static DEVICE_ATTR(start, 0444, part_start_show, NULL);
205 static DEVICE_ATTR(size, 0444, part_size_show, NULL);
206 static DEVICE_ATTR(ro, 0444, part_ro_show, NULL);
207 static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
208 static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
209 static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
210 static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
211 #ifdef CONFIG_FAIL_MAKE_REQUEST
212 static struct device_attribute dev_attr_fail =
213 	__ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
214 #endif
215 
216 static struct attribute *part_attrs[] = {
217 	&dev_attr_partition.attr,
218 	&dev_attr_start.attr,
219 	&dev_attr_size.attr,
220 	&dev_attr_ro.attr,
221 	&dev_attr_alignment_offset.attr,
222 	&dev_attr_discard_alignment.attr,
223 	&dev_attr_stat.attr,
224 	&dev_attr_inflight.attr,
225 #ifdef CONFIG_FAIL_MAKE_REQUEST
226 	&dev_attr_fail.attr,
227 #endif
228 	NULL
229 };
230 
231 static const struct attribute_group part_attr_group = {
232 	.attrs = part_attrs,
233 };
234 
235 static const struct attribute_group *part_attr_groups[] = {
236 	&part_attr_group,
237 #ifdef CONFIG_BLK_DEV_IO_TRACE
238 	&blk_trace_attr_group,
239 #endif
240 	NULL
241 };
242 
part_release(struct device * dev)243 static void part_release(struct device *dev)
244 {
245 	put_disk(dev_to_bdev(dev)->bd_disk);
246 	iput(dev_to_bdev(dev)->bd_inode);
247 }
248 
part_uevent(const struct device * dev,struct kobj_uevent_env * env)249 static int part_uevent(const struct device *dev, struct kobj_uevent_env *env)
250 {
251 	const struct block_device *part = dev_to_bdev(dev);
252 
253 	add_uevent_var(env, "PARTN=%u", part->bd_partno);
254 	if (part->bd_meta_info && part->bd_meta_info->volname[0])
255 		add_uevent_var(env, "PARTNAME=%s", part->bd_meta_info->volname);
256 	return 0;
257 }
258 
259 const struct device_type part_type = {
260 	.name		= "partition",
261 	.groups		= part_attr_groups,
262 	.release	= part_release,
263 	.uevent		= part_uevent,
264 };
265 
drop_partition(struct block_device * part)266 void drop_partition(struct block_device *part)
267 {
268 	lockdep_assert_held(&part->bd_disk->open_mutex);
269 
270 	xa_erase(&part->bd_disk->part_tbl, part->bd_partno);
271 	kobject_put(part->bd_holder_dir);
272 
273 	device_del(&part->bd_device);
274 	put_device(&part->bd_device);
275 }
276 
delete_partition(struct block_device * part)277 static void delete_partition(struct block_device *part)
278 {
279 	/*
280 	 * Remove the block device from the inode hash, so that it cannot be
281 	 * looked up any more even when openers still hold references.
282 	 */
283 	remove_inode_hash(part->bd_inode);
284 	bdev_mark_dead(part, false);
285 	drop_partition(part);
286 }
287 
whole_disk_show(struct device * dev,struct device_attribute * attr,char * buf)288 static ssize_t whole_disk_show(struct device *dev,
289 			       struct device_attribute *attr, char *buf)
290 {
291 	return 0;
292 }
293 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
294 
295 /*
296  * Must be called either with open_mutex held, before a disk can be opened or
297  * after all disk users are gone.
298  */
add_partition(struct gendisk * disk,int partno,sector_t start,sector_t len,int flags,struct partition_meta_info * info)299 static struct block_device *add_partition(struct gendisk *disk, int partno,
300 				sector_t start, sector_t len, int flags,
301 				struct partition_meta_info *info)
302 {
303 	dev_t devt = MKDEV(0, 0);
304 	struct device *ddev = disk_to_dev(disk);
305 	struct device *pdev;
306 	struct block_device *bdev;
307 	const char *dname;
308 	int err;
309 
310 	lockdep_assert_held(&disk->open_mutex);
311 
312 	if (partno >= DISK_MAX_PARTS)
313 		return ERR_PTR(-EINVAL);
314 
315 	/*
316 	 * Partitions are not supported on zoned block devices that are used as
317 	 * such.
318 	 */
319 	switch (disk->queue->limits.zoned) {
320 	case BLK_ZONED_HM:
321 		pr_warn("%s: partitions not supported on host managed zoned block device\n",
322 			disk->disk_name);
323 		return ERR_PTR(-ENXIO);
324 	case BLK_ZONED_HA:
325 		pr_info("%s: disabling host aware zoned block device support due to partitions\n",
326 			disk->disk_name);
327 		disk_set_zoned(disk, BLK_ZONED_NONE);
328 		break;
329 	case BLK_ZONED_NONE:
330 		break;
331 	}
332 
333 	if (xa_load(&disk->part_tbl, partno))
334 		return ERR_PTR(-EBUSY);
335 
336 	/* ensure we always have a reference to the whole disk */
337 	get_device(disk_to_dev(disk));
338 
339 	err = -ENOMEM;
340 	bdev = bdev_alloc(disk, partno);
341 	if (!bdev)
342 		goto out_put_disk;
343 
344 	bdev->bd_start_sect = start;
345 	bdev_set_nr_sectors(bdev, len);
346 
347 	pdev = &bdev->bd_device;
348 	dname = dev_name(ddev);
349 	if (isdigit(dname[strlen(dname) - 1]))
350 		dev_set_name(pdev, "%sp%d", dname, partno);
351 	else
352 		dev_set_name(pdev, "%s%d", dname, partno);
353 
354 	device_initialize(pdev);
355 	pdev->class = &block_class;
356 	pdev->type = &part_type;
357 	pdev->parent = ddev;
358 
359 	/* in consecutive minor range? */
360 	if (bdev->bd_partno < disk->minors) {
361 		devt = MKDEV(disk->major, disk->first_minor + bdev->bd_partno);
362 	} else {
363 		err = blk_alloc_ext_minor();
364 		if (err < 0)
365 			goto out_put;
366 		devt = MKDEV(BLOCK_EXT_MAJOR, err);
367 	}
368 	pdev->devt = devt;
369 
370 	if (info) {
371 		err = -ENOMEM;
372 		bdev->bd_meta_info = kmemdup(info, sizeof(*info), GFP_KERNEL);
373 		if (!bdev->bd_meta_info)
374 			goto out_put;
375 	}
376 
377 	/* delay uevent until 'holders' subdir is created */
378 	dev_set_uevent_suppress(pdev, 1);
379 	err = device_add(pdev);
380 	if (err)
381 		goto out_put;
382 
383 	err = -ENOMEM;
384 	bdev->bd_holder_dir = kobject_create_and_add("holders", &pdev->kobj);
385 	if (!bdev->bd_holder_dir)
386 		goto out_del;
387 
388 	dev_set_uevent_suppress(pdev, 0);
389 	if (flags & ADDPART_FLAG_WHOLEDISK) {
390 		err = device_create_file(pdev, &dev_attr_whole_disk);
391 		if (err)
392 			goto out_del;
393 	}
394 
395 	/* everything is up and running, commence */
396 	err = xa_insert(&disk->part_tbl, partno, bdev, GFP_KERNEL);
397 	if (err)
398 		goto out_del;
399 	bdev_add(bdev, devt);
400 
401 	/* suppress uevent if the disk suppresses it */
402 	if (!dev_get_uevent_suppress(ddev))
403 		kobject_uevent(&pdev->kobj, KOBJ_ADD);
404 	return bdev;
405 
406 out_del:
407 	kobject_put(bdev->bd_holder_dir);
408 	device_del(pdev);
409 out_put:
410 	put_device(pdev);
411 	return ERR_PTR(err);
412 out_put_disk:
413 	put_disk(disk);
414 	return ERR_PTR(err);
415 }
416 
partition_overlaps(struct gendisk * disk,sector_t start,sector_t length,int skip_partno)417 static bool partition_overlaps(struct gendisk *disk, sector_t start,
418 		sector_t length, int skip_partno)
419 {
420 	struct block_device *part;
421 	bool overlap = false;
422 	unsigned long idx;
423 
424 	rcu_read_lock();
425 	xa_for_each_start(&disk->part_tbl, idx, part, 1) {
426 		if (part->bd_partno != skip_partno &&
427 		    start < part->bd_start_sect + bdev_nr_sectors(part) &&
428 		    start + length > part->bd_start_sect) {
429 			overlap = true;
430 			break;
431 		}
432 	}
433 	rcu_read_unlock();
434 
435 	return overlap;
436 }
437 
bdev_add_partition(struct gendisk * disk,int partno,sector_t start,sector_t length)438 int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
439 		sector_t length)
440 {
441 	sector_t capacity = get_capacity(disk), end;
442 	struct block_device *part;
443 	int ret;
444 
445 	mutex_lock(&disk->open_mutex);
446 	if (check_add_overflow(start, length, &end)) {
447 		ret = -EINVAL;
448 		goto out;
449 	}
450 
451 	if (start >= capacity || end > capacity) {
452 		ret = -EINVAL;
453 		goto out;
454 	}
455 
456 	if (!disk_live(disk)) {
457 		ret = -ENXIO;
458 		goto out;
459 	}
460 
461 	if (disk->flags & GENHD_FL_NO_PART) {
462 		ret = -EINVAL;
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 
bdev_del_partition(struct gendisk * disk,int partno)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 (atomic_read(&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 
bdev_resize_partition(struct gendisk * disk,int partno,sector_t start,sector_t length)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 
disk_unlock_native_capacity(struct gendisk * disk)527 static bool disk_unlock_native_capacity(struct gendisk *disk)
528 {
529 	if (!disk->fops->unlock_native_capacity ||
530 	    test_and_set_bit(GD_NATIVE_CAPACITY, &disk->state)) {
531 		printk(KERN_CONT "truncated\n");
532 		return false;
533 	}
534 
535 	printk(KERN_CONT "enabling native capacity\n");
536 	disk->fops->unlock_native_capacity(disk);
537 	return true;
538 }
539 
blk_add_partition(struct gendisk * disk,struct parsed_partitions * state,int p)540 static bool blk_add_partition(struct gendisk *disk,
541 		struct parsed_partitions *state, int p)
542 {
543 	sector_t size = state->parts[p].size;
544 	sector_t from = state->parts[p].from;
545 	struct block_device *part;
546 
547 	if (!size)
548 		return true;
549 
550 	if (from >= get_capacity(disk)) {
551 		printk(KERN_WARNING
552 		       "%s: p%d start %llu is beyond EOD, ",
553 		       disk->disk_name, p, (unsigned long long) from);
554 		if (disk_unlock_native_capacity(disk))
555 			return false;
556 		return true;
557 	}
558 
559 	if (from + size > get_capacity(disk)) {
560 		printk(KERN_WARNING
561 		       "%s: p%d size %llu extends beyond EOD, ",
562 		       disk->disk_name, p, (unsigned long long) size);
563 
564 		if (disk_unlock_native_capacity(disk))
565 			return false;
566 
567 		/*
568 		 * We can not ignore partitions of broken tables created by for
569 		 * example camera firmware, but we limit them to the end of the
570 		 * disk to avoid creating invalid block devices.
571 		 */
572 		size = get_capacity(disk) - from;
573 	}
574 
575 	part = add_partition(disk, p, from, size, state->parts[p].flags,
576 			     &state->parts[p].info);
577 	if (IS_ERR(part)) {
578 		if (PTR_ERR(part) != -ENXIO) {
579 			printk(KERN_ERR " %s: p%d could not be added: %pe\n",
580 			       disk->disk_name, p, part);
581 		}
582 		return true;
583 	}
584 
585 	if (IS_BUILTIN(CONFIG_BLK_DEV_MD) &&
586 	    (state->parts[p].flags & ADDPART_FLAG_RAID))
587 		md_autodetect_dev(part->bd_dev);
588 
589 	return true;
590 }
591 
blk_add_partitions(struct gendisk * disk)592 static int blk_add_partitions(struct gendisk *disk)
593 {
594 	struct parsed_partitions *state;
595 	int ret = -EAGAIN, p;
596 
597 	if (!disk_has_partscan(disk))
598 		return 0;
599 
600 	state = check_partition(disk);
601 	if (!state)
602 		return 0;
603 	if (IS_ERR(state)) {
604 		/*
605 		 * I/O error reading the partition table.  If we tried to read
606 		 * beyond EOD, retry after unlocking the native capacity.
607 		 */
608 		if (PTR_ERR(state) == -ENOSPC) {
609 			printk(KERN_WARNING "%s: partition table beyond EOD, ",
610 			       disk->disk_name);
611 			if (disk_unlock_native_capacity(disk))
612 				return -EAGAIN;
613 		}
614 		return -EIO;
615 	}
616 
617 	/*
618 	 * Partitions are not supported on host managed zoned block devices.
619 	 */
620 	if (disk->queue->limits.zoned == BLK_ZONED_HM) {
621 		pr_warn("%s: ignoring partition table on host managed zoned block device\n",
622 			disk->disk_name);
623 		ret = 0;
624 		goto out_free_state;
625 	}
626 
627 	/*
628 	 * If we read beyond EOD, try unlocking native capacity even if the
629 	 * partition table was successfully read as we could be missing some
630 	 * partitions.
631 	 */
632 	if (state->access_beyond_eod) {
633 		printk(KERN_WARNING
634 		       "%s: partition table partially beyond EOD, ",
635 		       disk->disk_name);
636 		if (disk_unlock_native_capacity(disk))
637 			goto out_free_state;
638 	}
639 
640 	/* tell userspace that the media / partition table may have changed */
641 	kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
642 
643 	for (p = 1; p < state->limit; p++)
644 		if (!blk_add_partition(disk, state, p))
645 			goto out_free_state;
646 
647 	ret = 0;
648 out_free_state:
649 	free_partitions(state);
650 	return ret;
651 }
652 
bdev_disk_changed(struct gendisk * disk,bool invalidate)653 int bdev_disk_changed(struct gendisk *disk, bool invalidate)
654 {
655 	struct block_device *part;
656 	unsigned long idx;
657 	int ret = 0;
658 
659 	lockdep_assert_held(&disk->open_mutex);
660 
661 	if (!disk_live(disk))
662 		return -ENXIO;
663 
664 rescan:
665 	if (disk->open_partitions)
666 		return -EBUSY;
667 	sync_blockdev(disk->part0);
668 	invalidate_bdev(disk->part0);
669 
670 	xa_for_each_start(&disk->part_tbl, idx, part, 1)
671 		delete_partition(part);
672 	clear_bit(GD_NEED_PART_SCAN, &disk->state);
673 
674 	/*
675 	 * Historically we only set the capacity to zero for devices that
676 	 * support partitions (independ of actually having partitions created).
677 	 * Doing that is rather inconsistent, but changing it broke legacy
678 	 * udisks polling for legacy ide-cdrom devices.  Use the crude check
679 	 * below to get the sane behavior for most device while not breaking
680 	 * userspace for this particular setup.
681 	 */
682 	if (invalidate) {
683 		if (!(disk->flags & GENHD_FL_NO_PART) ||
684 		    !(disk->flags & GENHD_FL_REMOVABLE))
685 			set_capacity(disk, 0);
686 	}
687 
688 	if (get_capacity(disk)) {
689 		ret = blk_add_partitions(disk);
690 		if (ret == -EAGAIN)
691 			goto rescan;
692 	} else if (invalidate) {
693 		/*
694 		 * Tell userspace that the media / partition table may have
695 		 * changed.
696 		 */
697 		kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
698 	}
699 
700 	return ret;
701 }
702 /*
703  * Only exported for loop and dasd for historic reasons.  Don't use in new
704  * code!
705  */
706 EXPORT_SYMBOL_GPL(bdev_disk_changed);
707 
read_part_sector(struct parsed_partitions * state,sector_t n,Sector * p)708 void *read_part_sector(struct parsed_partitions *state, sector_t n, Sector *p)
709 {
710 	struct address_space *mapping = state->disk->part0->bd_inode->i_mapping;
711 	struct folio *folio;
712 
713 	if (n >= get_capacity(state->disk)) {
714 		state->access_beyond_eod = true;
715 		goto out;
716 	}
717 
718 	folio = read_mapping_folio(mapping, n >> PAGE_SECTORS_SHIFT, NULL);
719 	if (IS_ERR(folio))
720 		goto out;
721 
722 	p->v = folio;
723 	return folio_address(folio) + offset_in_folio(folio, n * SECTOR_SIZE);
724 out:
725 	p->v = NULL;
726 	return NULL;
727 }
728