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94ea4158 AV |
1 | /* |
2 | * Code extracted from drivers/block/genhd.c | |
3 | * Copyright (C) 1991-1998 Linus Torvalds | |
4 | * Re-organised Feb 1998 Russell King | |
5 | * | |
6 | * We now have independent partition support from the | |
7 | * block drivers, which allows all the partition code to | |
8 | * be grouped in one location, and it to be mostly self | |
9 | * contained. | |
10 | */ | |
11 | ||
12 | #include <linux/init.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/fs.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/kmod.h> | |
17 | #include <linux/ctype.h> | |
18 | #include <linux/genhd.h> | |
d1a5f2b4 | 19 | #include <linux/dax.h> |
94ea4158 AV |
20 | #include <linux/blktrace_api.h> |
21 | ||
22 | #include "partitions/check.h" | |
23 | ||
24 | #ifdef CONFIG_BLK_DEV_MD | |
25 | extern void md_autodetect_dev(dev_t dev); | |
26 | #endif | |
27 | ||
28 | /* | |
29 | * disk_name() is used by partition check code and the genhd driver. | |
30 | * It formats the devicename of the indicated disk into | |
31 | * the supplied buffer (of size at least 32), and returns | |
32 | * a pointer to that same buffer (for convenience). | |
33 | */ | |
34 | ||
35 | char *disk_name(struct gendisk *hd, int partno, char *buf) | |
36 | { | |
37 | if (!partno) | |
38 | snprintf(buf, BDEVNAME_SIZE, "%s", hd->disk_name); | |
39 | else if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) | |
40 | snprintf(buf, BDEVNAME_SIZE, "%sp%d", hd->disk_name, partno); | |
41 | else | |
42 | snprintf(buf, BDEVNAME_SIZE, "%s%d", hd->disk_name, partno); | |
43 | ||
44 | return buf; | |
45 | } | |
46 | ||
47 | const char *bdevname(struct block_device *bdev, char *buf) | |
48 | { | |
49 | return disk_name(bdev->bd_disk, bdev->bd_part->partno, buf); | |
50 | } | |
51 | ||
52 | EXPORT_SYMBOL(bdevname); | |
53 | ||
54 | /* | |
55 | * There's very little reason to use this, you should really | |
56 | * have a struct block_device just about everywhere and use | |
57 | * bdevname() instead. | |
58 | */ | |
59 | const char *__bdevname(dev_t dev, char *buffer) | |
60 | { | |
61 | scnprintf(buffer, BDEVNAME_SIZE, "unknown-block(%u,%u)", | |
62 | MAJOR(dev), MINOR(dev)); | |
63 | return buffer; | |
64 | } | |
65 | ||
66 | EXPORT_SYMBOL(__bdevname); | |
67 | ||
68 | static ssize_t part_partition_show(struct device *dev, | |
69 | struct device_attribute *attr, char *buf) | |
70 | { | |
71 | struct hd_struct *p = dev_to_part(dev); | |
72 | ||
73 | return sprintf(buf, "%d\n", p->partno); | |
74 | } | |
75 | ||
76 | static ssize_t part_start_show(struct device *dev, | |
77 | struct device_attribute *attr, char *buf) | |
78 | { | |
79 | struct hd_struct *p = dev_to_part(dev); | |
80 | ||
81 | return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect); | |
82 | } | |
83 | ||
84 | ssize_t part_size_show(struct device *dev, | |
85 | struct device_attribute *attr, char *buf) | |
86 | { | |
87 | struct hd_struct *p = dev_to_part(dev); | |
c83f6bf9 | 88 | return sprintf(buf, "%llu\n",(unsigned long long)part_nr_sects_read(p)); |
94ea4158 AV |
89 | } |
90 | ||
91 | static ssize_t part_ro_show(struct device *dev, | |
92 | struct device_attribute *attr, char *buf) | |
93 | { | |
94 | struct hd_struct *p = dev_to_part(dev); | |
95 | return sprintf(buf, "%d\n", p->policy ? 1 : 0); | |
96 | } | |
97 | ||
98 | static ssize_t part_alignment_offset_show(struct device *dev, | |
99 | struct device_attribute *attr, char *buf) | |
100 | { | |
101 | struct hd_struct *p = dev_to_part(dev); | |
102 | return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset); | |
103 | } | |
104 | ||
105 | static ssize_t part_discard_alignment_show(struct device *dev, | |
106 | struct device_attribute *attr, char *buf) | |
107 | { | |
108 | struct hd_struct *p = dev_to_part(dev); | |
109 | return sprintf(buf, "%u\n", p->discard_alignment); | |
110 | } | |
111 | ||
112 | ssize_t part_stat_show(struct device *dev, | |
113 | struct device_attribute *attr, char *buf) | |
114 | { | |
115 | struct hd_struct *p = dev_to_part(dev); | |
116 | int cpu; | |
117 | ||
118 | cpu = part_stat_lock(); | |
119 | part_round_stats(cpu, p); | |
120 | part_stat_unlock(); | |
121 | return sprintf(buf, | |
122 | "%8lu %8lu %8llu %8u " | |
123 | "%8lu %8lu %8llu %8u " | |
124 | "%8u %8u %8u" | |
125 | "\n", | |
126 | part_stat_read(p, ios[READ]), | |
127 | part_stat_read(p, merges[READ]), | |
128 | (unsigned long long)part_stat_read(p, sectors[READ]), | |
129 | jiffies_to_msecs(part_stat_read(p, ticks[READ])), | |
130 | part_stat_read(p, ios[WRITE]), | |
131 | part_stat_read(p, merges[WRITE]), | |
132 | (unsigned long long)part_stat_read(p, sectors[WRITE]), | |
133 | jiffies_to_msecs(part_stat_read(p, ticks[WRITE])), | |
134 | part_in_flight(p), | |
135 | jiffies_to_msecs(part_stat_read(p, io_ticks)), | |
136 | jiffies_to_msecs(part_stat_read(p, time_in_queue))); | |
137 | } | |
138 | ||
139 | ssize_t part_inflight_show(struct device *dev, | |
140 | struct device_attribute *attr, char *buf) | |
141 | { | |
142 | struct hd_struct *p = dev_to_part(dev); | |
143 | ||
144 | return sprintf(buf, "%8u %8u\n", atomic_read(&p->in_flight[0]), | |
145 | atomic_read(&p->in_flight[1])); | |
146 | } | |
147 | ||
148 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
149 | ssize_t part_fail_show(struct device *dev, | |
150 | struct device_attribute *attr, char *buf) | |
151 | { | |
152 | struct hd_struct *p = dev_to_part(dev); | |
153 | ||
154 | return sprintf(buf, "%d\n", p->make_it_fail); | |
155 | } | |
156 | ||
157 | ssize_t part_fail_store(struct device *dev, | |
158 | struct device_attribute *attr, | |
159 | const char *buf, size_t count) | |
160 | { | |
161 | struct hd_struct *p = dev_to_part(dev); | |
162 | int i; | |
163 | ||
164 | if (count > 0 && sscanf(buf, "%d", &i) > 0) | |
165 | p->make_it_fail = (i == 0) ? 0 : 1; | |
166 | ||
167 | return count; | |
168 | } | |
169 | #endif | |
170 | ||
171 | static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL); | |
172 | static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL); | |
173 | static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); | |
174 | static DEVICE_ATTR(ro, S_IRUGO, part_ro_show, NULL); | |
175 | static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL); | |
176 | static DEVICE_ATTR(discard_alignment, S_IRUGO, part_discard_alignment_show, | |
177 | NULL); | |
178 | static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL); | |
179 | static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL); | |
180 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
181 | static struct device_attribute dev_attr_fail = | |
182 | __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store); | |
183 | #endif | |
184 | ||
185 | static struct attribute *part_attrs[] = { | |
186 | &dev_attr_partition.attr, | |
187 | &dev_attr_start.attr, | |
188 | &dev_attr_size.attr, | |
189 | &dev_attr_ro.attr, | |
190 | &dev_attr_alignment_offset.attr, | |
191 | &dev_attr_discard_alignment.attr, | |
192 | &dev_attr_stat.attr, | |
193 | &dev_attr_inflight.attr, | |
194 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
195 | &dev_attr_fail.attr, | |
196 | #endif | |
197 | NULL | |
198 | }; | |
199 | ||
200 | static struct attribute_group part_attr_group = { | |
201 | .attrs = part_attrs, | |
202 | }; | |
203 | ||
204 | static const struct attribute_group *part_attr_groups[] = { | |
205 | &part_attr_group, | |
206 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
207 | &blk_trace_attr_group, | |
208 | #endif | |
209 | NULL | |
210 | }; | |
211 | ||
212 | static void part_release(struct device *dev) | |
213 | { | |
214 | struct hd_struct *p = dev_to_part(dev); | |
2da78092 | 215 | blk_free_devt(dev->devt); |
b54e5ed8 | 216 | hd_free_part(p); |
94ea4158 AV |
217 | kfree(p); |
218 | } | |
219 | ||
0d9c51a6 SM |
220 | static int part_uevent(struct device *dev, struct kobj_uevent_env *env) |
221 | { | |
222 | struct hd_struct *part = dev_to_part(dev); | |
223 | ||
224 | add_uevent_var(env, "PARTN=%u", part->partno); | |
225 | if (part->info && part->info->volname[0]) | |
226 | add_uevent_var(env, "PARTNAME=%s", part->info->volname); | |
227 | return 0; | |
228 | } | |
229 | ||
94ea4158 AV |
230 | struct device_type part_type = { |
231 | .name = "partition", | |
232 | .groups = part_attr_groups, | |
233 | .release = part_release, | |
0d9c51a6 | 234 | .uevent = part_uevent, |
94ea4158 AV |
235 | }; |
236 | ||
237 | static void delete_partition_rcu_cb(struct rcu_head *head) | |
238 | { | |
239 | struct hd_struct *part = container_of(head, struct hd_struct, rcu_head); | |
240 | ||
241 | part->start_sect = 0; | |
242 | part->nr_sects = 0; | |
243 | part_stat_set_all(part, 0); | |
244 | put_device(part_to_dev(part)); | |
245 | } | |
246 | ||
6c71013e | 247 | void __delete_partition(struct percpu_ref *ref) |
94ea4158 | 248 | { |
6c71013e | 249 | struct hd_struct *part = container_of(ref, struct hd_struct, ref); |
94ea4158 AV |
250 | call_rcu(&part->rcu_head, delete_partition_rcu_cb); |
251 | } | |
252 | ||
253 | void delete_partition(struct gendisk *disk, int partno) | |
254 | { | |
255 | struct disk_part_tbl *ptbl = disk->part_tbl; | |
256 | struct hd_struct *part; | |
257 | ||
258 | if (partno >= ptbl->len) | |
259 | return; | |
260 | ||
261 | part = ptbl->part[partno]; | |
262 | if (!part) | |
263 | return; | |
264 | ||
94ea4158 AV |
265 | rcu_assign_pointer(ptbl->part[partno], NULL); |
266 | rcu_assign_pointer(ptbl->last_lookup, NULL); | |
267 | kobject_put(part->holder_dir); | |
268 | device_del(part_to_dev(part)); | |
269 | ||
6c71013e | 270 | hd_struct_kill(part); |
94ea4158 AV |
271 | } |
272 | ||
273 | static ssize_t whole_disk_show(struct device *dev, | |
274 | struct device_attribute *attr, char *buf) | |
275 | { | |
276 | return 0; | |
277 | } | |
278 | static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH, | |
279 | whole_disk_show, NULL); | |
280 | ||
281 | struct hd_struct *add_partition(struct gendisk *disk, int partno, | |
282 | sector_t start, sector_t len, int flags, | |
283 | struct partition_meta_info *info) | |
284 | { | |
285 | struct hd_struct *p; | |
286 | dev_t devt = MKDEV(0, 0); | |
287 | struct device *ddev = disk_to_dev(disk); | |
288 | struct device *pdev; | |
289 | struct disk_part_tbl *ptbl; | |
290 | const char *dname; | |
291 | int err; | |
292 | ||
293 | err = disk_expand_part_tbl(disk, partno); | |
294 | if (err) | |
295 | return ERR_PTR(err); | |
296 | ptbl = disk->part_tbl; | |
297 | ||
298 | if (ptbl->part[partno]) | |
299 | return ERR_PTR(-EBUSY); | |
300 | ||
301 | p = kzalloc(sizeof(*p), GFP_KERNEL); | |
302 | if (!p) | |
303 | return ERR_PTR(-EBUSY); | |
304 | ||
305 | if (!init_part_stats(p)) { | |
306 | err = -ENOMEM; | |
307 | goto out_free; | |
308 | } | |
c83f6bf9 VG |
309 | |
310 | seqcount_init(&p->nr_sects_seq); | |
94ea4158 AV |
311 | pdev = part_to_dev(p); |
312 | ||
313 | p->start_sect = start; | |
314 | p->alignment_offset = | |
315 | queue_limit_alignment_offset(&disk->queue->limits, start); | |
316 | p->discard_alignment = | |
317 | queue_limit_discard_alignment(&disk->queue->limits, start); | |
318 | p->nr_sects = len; | |
319 | p->partno = partno; | |
320 | p->policy = get_disk_ro(disk); | |
321 | ||
322 | if (info) { | |
323 | struct partition_meta_info *pinfo = alloc_part_info(disk); | |
324 | if (!pinfo) | |
325 | goto out_free_stats; | |
326 | memcpy(pinfo, info, sizeof(*info)); | |
327 | p->info = pinfo; | |
328 | } | |
329 | ||
330 | dname = dev_name(ddev); | |
331 | if (isdigit(dname[strlen(dname) - 1])) | |
332 | dev_set_name(pdev, "%sp%d", dname, partno); | |
333 | else | |
334 | dev_set_name(pdev, "%s%d", dname, partno); | |
335 | ||
336 | device_initialize(pdev); | |
337 | pdev->class = &block_class; | |
338 | pdev->type = &part_type; | |
339 | pdev->parent = ddev; | |
340 | ||
341 | err = blk_alloc_devt(p, &devt); | |
342 | if (err) | |
343 | goto out_free_info; | |
344 | pdev->devt = devt; | |
345 | ||
346 | /* delay uevent until 'holders' subdir is created */ | |
347 | dev_set_uevent_suppress(pdev, 1); | |
348 | err = device_add(pdev); | |
349 | if (err) | |
350 | goto out_put; | |
351 | ||
352 | err = -ENOMEM; | |
353 | p->holder_dir = kobject_create_and_add("holders", &pdev->kobj); | |
354 | if (!p->holder_dir) | |
355 | goto out_del; | |
356 | ||
357 | dev_set_uevent_suppress(pdev, 0); | |
358 | if (flags & ADDPART_FLAG_WHOLEDISK) { | |
359 | err = device_create_file(pdev, &dev_attr_whole_disk); | |
360 | if (err) | |
361 | goto out_del; | |
362 | } | |
363 | ||
364 | /* everything is up and running, commence */ | |
365 | rcu_assign_pointer(ptbl->part[partno], p); | |
366 | ||
367 | /* suppress uevent if the disk suppresses it */ | |
368 | if (!dev_get_uevent_suppress(ddev)) | |
369 | kobject_uevent(&pdev->kobj, KOBJ_ADD); | |
370 | ||
6c71013e ML |
371 | if (!hd_ref_init(p)) |
372 | return p; | |
94ea4158 AV |
373 | |
374 | out_free_info: | |
375 | free_part_info(p); | |
376 | out_free_stats: | |
377 | free_part_stats(p); | |
378 | out_free: | |
379 | kfree(p); | |
380 | return ERR_PTR(err); | |
381 | out_del: | |
382 | kobject_put(p->holder_dir); | |
383 | device_del(pdev); | |
384 | out_put: | |
385 | put_device(pdev); | |
386 | blk_free_devt(devt); | |
387 | return ERR_PTR(err); | |
388 | } | |
389 | ||
390 | static bool disk_unlock_native_capacity(struct gendisk *disk) | |
391 | { | |
392 | const struct block_device_operations *bdops = disk->fops; | |
393 | ||
394 | if (bdops->unlock_native_capacity && | |
395 | !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) { | |
396 | printk(KERN_CONT "enabling native capacity\n"); | |
397 | bdops->unlock_native_capacity(disk); | |
398 | disk->flags |= GENHD_FL_NATIVE_CAPACITY; | |
399 | return true; | |
400 | } else { | |
401 | printk(KERN_CONT "truncated\n"); | |
402 | return false; | |
403 | } | |
404 | } | |
405 | ||
fe316bf2 | 406 | static int drop_partitions(struct gendisk *disk, struct block_device *bdev) |
94ea4158 | 407 | { |
94ea4158 AV |
408 | struct disk_part_iter piter; |
409 | struct hd_struct *part; | |
fe316bf2 | 410 | int res; |
94ea4158 | 411 | |
77032ca6 | 412 | if (bdev->bd_part_count || bdev->bd_super) |
94ea4158 AV |
413 | return -EBUSY; |
414 | res = invalidate_partition(disk, 0); | |
415 | if (res) | |
416 | return res; | |
417 | ||
418 | disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY); | |
419 | while ((part = disk_part_iter_next(&piter))) | |
420 | delete_partition(disk, part->partno); | |
421 | disk_part_iter_exit(&piter); | |
422 | ||
fe316bf2 JN |
423 | return 0; |
424 | } | |
425 | ||
426 | int rescan_partitions(struct gendisk *disk, struct block_device *bdev) | |
427 | { | |
428 | struct parsed_partitions *state = NULL; | |
429 | struct hd_struct *part; | |
430 | int p, highest, res; | |
431 | rescan: | |
432 | if (state && !IS_ERR(state)) { | |
ac2e5327 | 433 | free_partitions(state); |
fe316bf2 JN |
434 | state = NULL; |
435 | } | |
436 | ||
437 | res = drop_partitions(disk, bdev); | |
438 | if (res) | |
439 | return res; | |
440 | ||
94ea4158 AV |
441 | if (disk->fops->revalidate_disk) |
442 | disk->fops->revalidate_disk(disk); | |
25520d55 | 443 | blk_integrity_revalidate(disk); |
94ea4158 AV |
444 | check_disk_size_change(disk, bdev); |
445 | bdev->bd_invalidated = 0; | |
446 | if (!get_capacity(disk) || !(state = check_partition(disk, bdev))) | |
447 | return 0; | |
448 | if (IS_ERR(state)) { | |
449 | /* | |
450 | * I/O error reading the partition table. If any | |
451 | * partition code tried to read beyond EOD, retry | |
452 | * after unlocking native capacity. | |
453 | */ | |
454 | if (PTR_ERR(state) == -ENOSPC) { | |
455 | printk(KERN_WARNING "%s: partition table beyond EOD, ", | |
456 | disk->disk_name); | |
457 | if (disk_unlock_native_capacity(disk)) | |
458 | goto rescan; | |
459 | } | |
460 | return -EIO; | |
461 | } | |
462 | /* | |
463 | * If any partition code tried to read beyond EOD, try | |
464 | * unlocking native capacity even if partition table is | |
465 | * successfully read as we could be missing some partitions. | |
466 | */ | |
467 | if (state->access_beyond_eod) { | |
468 | printk(KERN_WARNING | |
469 | "%s: partition table partially beyond EOD, ", | |
470 | disk->disk_name); | |
471 | if (disk_unlock_native_capacity(disk)) | |
472 | goto rescan; | |
473 | } | |
474 | ||
475 | /* tell userspace that the media / partition table may have changed */ | |
476 | kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE); | |
477 | ||
478 | /* Detect the highest partition number and preallocate | |
479 | * disk->part_tbl. This is an optimization and not strictly | |
480 | * necessary. | |
481 | */ | |
482 | for (p = 1, highest = 0; p < state->limit; p++) | |
483 | if (state->parts[p].size) | |
484 | highest = p; | |
485 | ||
486 | disk_expand_part_tbl(disk, highest); | |
487 | ||
488 | /* add partitions */ | |
489 | for (p = 1; p < state->limit; p++) { | |
490 | sector_t size, from; | |
491 | struct partition_meta_info *info = NULL; | |
492 | ||
493 | size = state->parts[p].size; | |
494 | if (!size) | |
495 | continue; | |
496 | ||
497 | from = state->parts[p].from; | |
498 | if (from >= get_capacity(disk)) { | |
499 | printk(KERN_WARNING | |
500 | "%s: p%d start %llu is beyond EOD, ", | |
501 | disk->disk_name, p, (unsigned long long) from); | |
502 | if (disk_unlock_native_capacity(disk)) | |
503 | goto rescan; | |
504 | continue; | |
505 | } | |
506 | ||
507 | if (from + size > get_capacity(disk)) { | |
508 | printk(KERN_WARNING | |
509 | "%s: p%d size %llu extends beyond EOD, ", | |
510 | disk->disk_name, p, (unsigned long long) size); | |
511 | ||
512 | if (disk_unlock_native_capacity(disk)) { | |
513 | /* free state and restart */ | |
514 | goto rescan; | |
515 | } else { | |
516 | /* | |
517 | * we can not ignore partitions of broken tables | |
518 | * created by for example camera firmware, but | |
519 | * we limit them to the end of the disk to avoid | |
520 | * creating invalid block devices | |
521 | */ | |
522 | size = get_capacity(disk) - from; | |
523 | } | |
524 | } | |
525 | ||
526 | if (state->parts[p].has_info) | |
527 | info = &state->parts[p].info; | |
528 | part = add_partition(disk, p, from, size, | |
529 | state->parts[p].flags, | |
530 | &state->parts[p].info); | |
531 | if (IS_ERR(part)) { | |
532 | printk(KERN_ERR " %s: p%d could not be added: %ld\n", | |
533 | disk->disk_name, p, -PTR_ERR(part)); | |
534 | continue; | |
535 | } | |
536 | #ifdef CONFIG_BLK_DEV_MD | |
537 | if (state->parts[p].flags & ADDPART_FLAG_RAID) | |
538 | md_autodetect_dev(part_to_dev(part)->devt); | |
539 | #endif | |
540 | } | |
ac2e5327 | 541 | free_partitions(state); |
94ea4158 AV |
542 | return 0; |
543 | } | |
544 | ||
fe316bf2 JN |
545 | int invalidate_partitions(struct gendisk *disk, struct block_device *bdev) |
546 | { | |
547 | int res; | |
548 | ||
549 | if (!bdev->bd_invalidated) | |
550 | return 0; | |
551 | ||
552 | res = drop_partitions(disk, bdev); | |
553 | if (res) | |
554 | return res; | |
555 | ||
556 | set_capacity(disk, 0); | |
557 | check_disk_size_change(disk, bdev); | |
558 | bdev->bd_invalidated = 0; | |
559 | /* tell userspace that the media / partition table may have changed */ | |
560 | kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE); | |
561 | ||
562 | return 0; | |
563 | } | |
564 | ||
d1a5f2b4 | 565 | static struct page *read_pagecache_sector(struct block_device *bdev, sector_t n) |
94ea4158 AV |
566 | { |
567 | struct address_space *mapping = bdev->bd_inode->i_mapping; | |
d1a5f2b4 | 568 | |
09cbfeaf KS |
569 | return read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)), |
570 | NULL); | |
d1a5f2b4 DW |
571 | } |
572 | ||
573 | unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p) | |
574 | { | |
94ea4158 AV |
575 | struct page *page; |
576 | ||
d1a5f2b4 DW |
577 | /* don't populate page cache for dax capable devices */ |
578 | if (IS_DAX(bdev->bd_inode)) | |
579 | page = read_dax_sector(bdev, n); | |
580 | else | |
581 | page = read_pagecache_sector(bdev, n); | |
582 | ||
94ea4158 AV |
583 | if (!IS_ERR(page)) { |
584 | if (PageError(page)) | |
585 | goto fail; | |
586 | p->v = page; | |
09cbfeaf | 587 | return (unsigned char *)page_address(page) + ((n & ((1 << (PAGE_SHIFT - 9)) - 1)) << 9); |
94ea4158 | 588 | fail: |
09cbfeaf | 589 | put_page(page); |
94ea4158 AV |
590 | } |
591 | p->v = NULL; | |
592 | return NULL; | |
593 | } | |
594 | ||
595 | EXPORT_SYMBOL(read_dev_sector); |