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TOMOYO Linux Cross Reference
Linux/block/partition-generic.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  Code extracted from drivers/block/genhd.c
  4  *  Copyright (C) 1991-1998  Linus Torvalds
  5  *  Re-organised Feb 1998 Russell King
  6  *
  7  *  We now have independent partition support from the
  8  *  block drivers, which allows all the partition code to
  9  *  be grouped in one location, and it to be mostly self
 10  *  contained.
 11  */
 12 
 13 #include <linux/init.h>
 14 #include <linux/module.h>
 15 #include <linux/fs.h>
 16 #include <linux/slab.h>
 17 #include <linux/kmod.h>
 18 #include <linux/ctype.h>
 19 #include <linux/genhd.h>
 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 const char *bio_devname(struct bio *bio, char *buf)
 55 {
 56         return disk_name(bio->bi_disk, bio->bi_partno, buf);
 57 }
 58 EXPORT_SYMBOL(bio_devname);
 59 
 60 /*
 61  * There's very little reason to use this, you should really
 62  * have a struct block_device just about everywhere and use
 63  * bdevname() instead.
 64  */
 65 const char *__bdevname(dev_t dev, char *buffer)
 66 {
 67         scnprintf(buffer, BDEVNAME_SIZE, "unknown-block(%u,%u)",
 68                                 MAJOR(dev), MINOR(dev));
 69         return buffer;
 70 }
 71 
 72 EXPORT_SYMBOL(__bdevname);
 73 
 74 static ssize_t part_partition_show(struct device *dev,
 75                                    struct device_attribute *attr, char *buf)
 76 {
 77         struct hd_struct *p = dev_to_part(dev);
 78 
 79         return sprintf(buf, "%d\n", p->partno);
 80 }
 81 
 82 static ssize_t part_start_show(struct device *dev,
 83                                struct device_attribute *attr, char *buf)
 84 {
 85         struct hd_struct *p = dev_to_part(dev);
 86 
 87         return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect);
 88 }
 89 
 90 ssize_t part_size_show(struct device *dev,
 91                        struct device_attribute *attr, char *buf)
 92 {
 93         struct hd_struct *p = dev_to_part(dev);
 94         return sprintf(buf, "%llu\n",(unsigned long long)part_nr_sects_read(p));
 95 }
 96 
 97 static ssize_t part_ro_show(struct device *dev,
 98                             struct device_attribute *attr, char *buf)
 99 {
100         struct hd_struct *p = dev_to_part(dev);
101         return sprintf(buf, "%d\n", p->policy ? 1 : 0);
102 }
103 
104 static ssize_t part_alignment_offset_show(struct device *dev,
105                                           struct device_attribute *attr, char *buf)
106 {
107         struct hd_struct *p = dev_to_part(dev);
108         return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset);
109 }
110 
111 static ssize_t part_discard_alignment_show(struct device *dev,
112                                            struct device_attribute *attr, char *buf)
113 {
114         struct hd_struct *p = dev_to_part(dev);
115         return sprintf(buf, "%u\n", p->discard_alignment);
116 }
117 
118 ssize_t part_stat_show(struct device *dev,
119                        struct device_attribute *attr, char *buf)
120 {
121         struct hd_struct *p = dev_to_part(dev);
122         struct request_queue *q = part_to_disk(p)->queue;
123         unsigned int inflight;
124 
125         inflight = part_in_flight(q, p);
126         return sprintf(buf,
127                 "%8lu %8lu %8llu %8u "
128                 "%8lu %8lu %8llu %8u "
129                 "%8u %8u %8u "
130                 "%8lu %8lu %8llu %8u"
131                 "\n",
132                 part_stat_read(p, ios[STAT_READ]),
133                 part_stat_read(p, merges[STAT_READ]),
134                 (unsigned long long)part_stat_read(p, sectors[STAT_READ]),
135                 (unsigned int)part_stat_read_msecs(p, STAT_READ),
136                 part_stat_read(p, ios[STAT_WRITE]),
137                 part_stat_read(p, merges[STAT_WRITE]),
138                 (unsigned long long)part_stat_read(p, sectors[STAT_WRITE]),
139                 (unsigned int)part_stat_read_msecs(p, STAT_WRITE),
140                 inflight,
141                 jiffies_to_msecs(part_stat_read(p, io_ticks)),
142                 jiffies_to_msecs(part_stat_read(p, time_in_queue)),
143                 part_stat_read(p, ios[STAT_DISCARD]),
144                 part_stat_read(p, merges[STAT_DISCARD]),
145                 (unsigned long long)part_stat_read(p, sectors[STAT_DISCARD]),
146                 (unsigned int)part_stat_read_msecs(p, STAT_DISCARD));
147 }
148 
149 ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
150                            char *buf)
151 {
152         struct hd_struct *p = dev_to_part(dev);
153         struct request_queue *q = part_to_disk(p)->queue;
154         unsigned int inflight[2];
155 
156         part_in_flight_rw(q, p, inflight);
157         return sprintf(buf, "%8u %8u\n", inflight[0], inflight[1]);
158 }
159 
160 #ifdef CONFIG_FAIL_MAKE_REQUEST
161 ssize_t part_fail_show(struct device *dev,
162                        struct device_attribute *attr, char *buf)
163 {
164         struct hd_struct *p = dev_to_part(dev);
165 
166         return sprintf(buf, "%d\n", p->make_it_fail);
167 }
168 
169 ssize_t part_fail_store(struct device *dev,
170                         struct device_attribute *attr,
171                         const char *buf, size_t count)
172 {
173         struct hd_struct *p = dev_to_part(dev);
174         int i;
175 
176         if (count > 0 && sscanf(buf, "%d", &i) > 0)
177                 p->make_it_fail = (i == 0) ? 0 : 1;
178 
179         return count;
180 }
181 #endif
182 
183 static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
184 static DEVICE_ATTR(start, 0444, part_start_show, NULL);
185 static DEVICE_ATTR(size, 0444, part_size_show, NULL);
186 static DEVICE_ATTR(ro, 0444, part_ro_show, NULL);
187 static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
188 static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
189 static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
190 static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
191 #ifdef CONFIG_FAIL_MAKE_REQUEST
192 static struct device_attribute dev_attr_fail =
193         __ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
194 #endif
195 
196 static struct attribute *part_attrs[] = {
197         &dev_attr_partition.attr,
198         &dev_attr_start.attr,
199         &dev_attr_size.attr,
200         &dev_attr_ro.attr,
201         &dev_attr_alignment_offset.attr,
202         &dev_attr_discard_alignment.attr,
203         &dev_attr_stat.attr,
204         &dev_attr_inflight.attr,
205 #ifdef CONFIG_FAIL_MAKE_REQUEST
206         &dev_attr_fail.attr,
207 #endif
208         NULL
209 };
210 
211 static struct attribute_group part_attr_group = {
212         .attrs = part_attrs,
213 };
214 
215 static const struct attribute_group *part_attr_groups[] = {
216         &part_attr_group,
217 #ifdef CONFIG_BLK_DEV_IO_TRACE
218         &blk_trace_attr_group,
219 #endif
220         NULL
221 };
222 
223 static void part_release(struct device *dev)
224 {
225         struct hd_struct *p = dev_to_part(dev);
226         blk_free_devt(dev->devt);
227         hd_free_part(p);
228         kfree(p);
229 }
230 
231 static int part_uevent(struct device *dev, struct kobj_uevent_env *env)
232 {
233         struct hd_struct *part = dev_to_part(dev);
234 
235         add_uevent_var(env, "PARTN=%u", part->partno);
236         if (part->info && part->info->volname[0])
237                 add_uevent_var(env, "PARTNAME=%s", part->info->volname);
238         return 0;
239 }
240 
241 struct device_type part_type = {
242         .name           = "partition",
243         .groups         = part_attr_groups,
244         .release        = part_release,
245         .uevent         = part_uevent,
246 };
247 
248 static void delete_partition_work_fn(struct work_struct *work)
249 {
250         struct hd_struct *part = container_of(to_rcu_work(work), struct hd_struct,
251                                         rcu_work);
252 
253         part->start_sect = 0;
254         part->nr_sects = 0;
255         part_stat_set_all(part, 0);
256         put_device(part_to_dev(part));
257 }
258 
259 void __delete_partition(struct percpu_ref *ref)
260 {
261         struct hd_struct *part = container_of(ref, struct hd_struct, ref);
262         INIT_RCU_WORK(&part->rcu_work, delete_partition_work_fn);
263         queue_rcu_work(system_wq, &part->rcu_work);
264 }
265 
266 /*
267  * Must be called either with bd_mutex held, before a disk can be opened or
268  * after all disk users are gone.
269  */
270 void delete_partition(struct gendisk *disk, int partno)
271 {
272         struct disk_part_tbl *ptbl =
273                 rcu_dereference_protected(disk->part_tbl, 1);
274         struct hd_struct *part;
275 
276         if (partno >= ptbl->len)
277                 return;
278 
279         part = rcu_dereference_protected(ptbl->part[partno], 1);
280         if (!part)
281                 return;
282 
283         rcu_assign_pointer(ptbl->part[partno], NULL);
284         rcu_assign_pointer(ptbl->last_lookup, NULL);
285         kobject_put(part->holder_dir);
286         device_del(part_to_dev(part));
287 
288         /*
289          * Remove gendisk pointer from idr so that it cannot be looked up
290          * while RCU period before freeing gendisk is running to prevent
291          * use-after-free issues. Note that the device number stays
292          * "in-use" until we really free the gendisk.
293          */
294         blk_invalidate_devt(part_devt(part));
295         hd_struct_kill(part);
296 }
297 
298 static ssize_t whole_disk_show(struct device *dev,
299                                struct device_attribute *attr, char *buf)
300 {
301         return 0;
302 }
303 static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
304 
305 /*
306  * Must be called either with bd_mutex held, before a disk can be opened or
307  * after all disk users are gone.
308  */
309 struct hd_struct *add_partition(struct gendisk *disk, int partno,
310                                 sector_t start, sector_t len, int flags,
311                                 struct partition_meta_info *info)
312 {
313         struct hd_struct *p;
314         dev_t devt = MKDEV(0, 0);
315         struct device *ddev = disk_to_dev(disk);
316         struct device *pdev;
317         struct disk_part_tbl *ptbl;
318         const char *dname;
319         int err;
320 
321         err = disk_expand_part_tbl(disk, partno);
322         if (err)
323                 return ERR_PTR(err);
324         ptbl = rcu_dereference_protected(disk->part_tbl, 1);
325 
326         if (ptbl->part[partno])
327                 return ERR_PTR(-EBUSY);
328 
329         p = kzalloc(sizeof(*p), GFP_KERNEL);
330         if (!p)
331                 return ERR_PTR(-EBUSY);
332 
333         if (!init_part_stats(p)) {
334                 err = -ENOMEM;
335                 goto out_free;
336         }
337 
338         seqcount_init(&p->nr_sects_seq);
339         pdev = part_to_dev(p);
340 
341         p->start_sect = start;
342         p->alignment_offset =
343                 queue_limit_alignment_offset(&disk->queue->limits, start);
344         p->discard_alignment =
345                 queue_limit_discard_alignment(&disk->queue->limits, start);
346         p->nr_sects = len;
347         p->partno = partno;
348         p->policy = get_disk_ro(disk);
349 
350         if (info) {
351                 struct partition_meta_info *pinfo = alloc_part_info(disk);
352                 if (!pinfo) {
353                         err = -ENOMEM;
354                         goto out_free_stats;
355                 }
356                 memcpy(pinfo, info, sizeof(*info));
357                 p->info = pinfo;
358         }
359 
360         dname = dev_name(ddev);
361         if (isdigit(dname[strlen(dname) - 1]))
362                 dev_set_name(pdev, "%sp%d", dname, partno);
363         else
364                 dev_set_name(pdev, "%s%d", dname, partno);
365 
366         device_initialize(pdev);
367         pdev->class = &block_class;
368         pdev->type = &part_type;
369         pdev->parent = ddev;
370 
371         err = blk_alloc_devt(p, &devt);
372         if (err)
373                 goto out_free_info;
374         pdev->devt = devt;
375 
376         /* delay uevent until 'holders' subdir is created */
377         dev_set_uevent_suppress(pdev, 1);
378         err = device_add(pdev);
379         if (err)
380                 goto out_put;
381 
382         err = -ENOMEM;
383         p->holder_dir = kobject_create_and_add("holders", &pdev->kobj);
384         if (!p->holder_dir)
385                 goto out_del;
386 
387         dev_set_uevent_suppress(pdev, 0);
388         if (flags & ADDPART_FLAG_WHOLEDISK) {
389                 err = device_create_file(pdev, &dev_attr_whole_disk);
390                 if (err)
391                         goto out_del;
392         }
393 
394         err = hd_ref_init(p);
395         if (err) {
396                 if (flags & ADDPART_FLAG_WHOLEDISK)
397                         goto out_remove_file;
398                 goto out_del;
399         }
400 
401         /* everything is up and running, commence */
402         rcu_assign_pointer(ptbl->part[partno], p);
403 
404         /* suppress uevent if the disk suppresses it */
405         if (!dev_get_uevent_suppress(ddev))
406                 kobject_uevent(&pdev->kobj, KOBJ_ADD);
407         return p;
408 
409 out_free_info:
410         free_part_info(p);
411 out_free_stats:
412         free_part_stats(p);
413 out_free:
414         kfree(p);
415         return ERR_PTR(err);
416 out_remove_file:
417         device_remove_file(pdev, &dev_attr_whole_disk);
418 out_del:
419         kobject_put(p->holder_dir);
420         device_del(pdev);
421 out_put:
422         put_device(pdev);
423         return ERR_PTR(err);
424 }
425 
426 static bool disk_unlock_native_capacity(struct gendisk *disk)
427 {
428         const struct block_device_operations *bdops = disk->fops;
429 
430         if (bdops->unlock_native_capacity &&
431             !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) {
432                 printk(KERN_CONT "enabling native capacity\n");
433                 bdops->unlock_native_capacity(disk);
434                 disk->flags |= GENHD_FL_NATIVE_CAPACITY;
435                 return true;
436         } else {
437                 printk(KERN_CONT "truncated\n");
438                 return false;
439         }
440 }
441 
442 static int drop_partitions(struct gendisk *disk, struct block_device *bdev)
443 {
444         struct disk_part_iter piter;
445         struct hd_struct *part;
446         int res;
447 
448         if (bdev->bd_part_count || bdev->bd_super)
449                 return -EBUSY;
450         res = invalidate_partition(disk, 0);
451         if (res)
452                 return res;
453 
454         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
455         while ((part = disk_part_iter_next(&piter)))
456                 delete_partition(disk, part->partno);
457         disk_part_iter_exit(&piter);
458 
459         return 0;
460 }
461 
462 static bool part_zone_aligned(struct gendisk *disk,
463                               struct block_device *bdev,
464                               sector_t from, sector_t size)
465 {
466         unsigned int zone_sectors = bdev_zone_sectors(bdev);
467 
468         /*
469          * If this function is called, then the disk is a zoned block device
470          * (host-aware or host-managed). This can be detected even if the
471          * zoned block device support is disabled (CONFIG_BLK_DEV_ZONED not
472          * set). In this case, however, only host-aware devices will be seen
473          * as a block device is not created for host-managed devices. Without
474          * zoned block device support, host-aware drives can still be used as
475          * regular block devices (no zone operation) and their zone size will
476          * be reported as 0. Allow this case.
477          */
478         if (!zone_sectors)
479                 return true;
480 
481         /*
482          * Check partition start and size alignement. If the drive has a
483          * smaller last runt zone, ignore it and allow the partition to
484          * use it. Check the zone size too: it should be a power of 2 number
485          * of sectors.
486          */
487         if (WARN_ON_ONCE(!is_power_of_2(zone_sectors))) {
488                 u32 rem;
489 
490                 div_u64_rem(from, zone_sectors, &rem);
491                 if (rem)
492                         return false;
493                 if ((from + size) < get_capacity(disk)) {
494                         div_u64_rem(size, zone_sectors, &rem);
495                         if (rem)
496                                 return false;
497                 }
498 
499         } else {
500 
501                 if (from & (zone_sectors - 1))
502                         return false;
503                 if ((from + size) < get_capacity(disk) &&
504                     (size & (zone_sectors - 1)))
505                         return false;
506 
507         }
508 
509         return true;
510 }
511 
512 int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
513 {
514         struct parsed_partitions *state = NULL;
515         struct hd_struct *part;
516         int p, highest, res;
517 rescan:
518         if (state && !IS_ERR(state)) {
519                 free_partitions(state);
520                 state = NULL;
521         }
522 
523         res = drop_partitions(disk, bdev);
524         if (res)
525                 return res;
526 
527         if (disk->fops->revalidate_disk)
528                 disk->fops->revalidate_disk(disk);
529         check_disk_size_change(disk, bdev, true);
530         bdev->bd_invalidated = 0;
531         if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
532                 return 0;
533         if (IS_ERR(state)) {
534                 /*
535                  * I/O error reading the partition table.  If any
536                  * partition code tried to read beyond EOD, retry
537                  * after unlocking native capacity.
538                  */
539                 if (PTR_ERR(state) == -ENOSPC) {
540                         printk(KERN_WARNING "%s: partition table beyond EOD, ",
541                                disk->disk_name);
542                         if (disk_unlock_native_capacity(disk))
543                                 goto rescan;
544                 }
545                 return -EIO;
546         }
547         /*
548          * If any partition code tried to read beyond EOD, try
549          * unlocking native capacity even if partition table is
550          * successfully read as we could be missing some partitions.
551          */
552         if (state->access_beyond_eod) {
553                 printk(KERN_WARNING
554                        "%s: partition table partially beyond EOD, ",
555                        disk->disk_name);
556                 if (disk_unlock_native_capacity(disk))
557                         goto rescan;
558         }
559 
560         /* tell userspace that the media / partition table may have changed */
561         kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
562 
563         /* Detect the highest partition number and preallocate
564          * disk->part_tbl.  This is an optimization and not strictly
565          * necessary.
566          */
567         for (p = 1, highest = 0; p < state->limit; p++)
568                 if (state->parts[p].size)
569                         highest = p;
570 
571         disk_expand_part_tbl(disk, highest);
572 
573         /* add partitions */
574         for (p = 1; p < state->limit; p++) {
575                 sector_t size, from;
576 
577                 size = state->parts[p].size;
578                 if (!size)
579                         continue;
580 
581                 from = state->parts[p].from;
582                 if (from >= get_capacity(disk)) {
583                         printk(KERN_WARNING
584                                "%s: p%d start %llu is beyond EOD, ",
585                                disk->disk_name, p, (unsigned long long) from);
586                         if (disk_unlock_native_capacity(disk))
587                                 goto rescan;
588                         continue;
589                 }
590 
591                 if (from + size > get_capacity(disk)) {
592                         printk(KERN_WARNING
593                                "%s: p%d size %llu extends beyond EOD, ",
594                                disk->disk_name, p, (unsigned long long) size);
595 
596                         if (disk_unlock_native_capacity(disk)) {
597                                 /* free state and restart */
598                                 goto rescan;
599                         } else {
600                                 /*
601                                  * we can not ignore partitions of broken tables
602                                  * created by for example camera firmware, but
603                                  * we limit them to the end of the disk to avoid
604                                  * creating invalid block devices
605                                  */
606                                 size = get_capacity(disk) - from;
607                         }
608                 }
609 
610                 /*
611                  * On a zoned block device, partitions should be aligned on the
612                  * device zone size (i.e. zone boundary crossing not allowed).
613                  * Otherwise, resetting the write pointer of the last zone of
614                  * one partition may impact the following partition.
615                  */
616                 if (bdev_is_zoned(bdev) &&
617                     !part_zone_aligned(disk, bdev, from, size)) {
618                         printk(KERN_WARNING
619                                "%s: p%d start %llu+%llu is not zone aligned\n",
620                                disk->disk_name, p, (unsigned long long) from,
621                                (unsigned long long) size);
622                         continue;
623                 }
624 
625                 part = add_partition(disk, p, from, size,
626                                      state->parts[p].flags,
627                                      &state->parts[p].info);
628                 if (IS_ERR(part)) {
629                         printk(KERN_ERR " %s: p%d could not be added: %ld\n",
630                                disk->disk_name, p, -PTR_ERR(part));
631                         continue;
632                 }
633 #ifdef CONFIG_BLK_DEV_MD
634                 if (state->parts[p].flags & ADDPART_FLAG_RAID)
635                         md_autodetect_dev(part_to_dev(part)->devt);
636 #endif
637         }
638         free_partitions(state);
639         return 0;
640 }
641 
642 int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
643 {
644         int res;
645 
646         if (!bdev->bd_invalidated)
647                 return 0;
648 
649         res = drop_partitions(disk, bdev);
650         if (res)
651                 return res;
652 
653         set_capacity(disk, 0);
654         check_disk_size_change(disk, bdev, false);
655         bdev->bd_invalidated = 0;
656         /* tell userspace that the media / partition table may have changed */
657         kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
658 
659         return 0;
660 }
661 
662 unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
663 {
664         struct address_space *mapping = bdev->bd_inode->i_mapping;
665         struct page *page;
666 
667         page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)), NULL);
668         if (!IS_ERR(page)) {
669                 if (PageError(page))
670                         goto fail;
671                 p->v = page;
672                 return (unsigned char *)page_address(page) +  ((n & ((1 << (PAGE_SHIFT - 9)) - 1)) << 9);
673 fail:
674                 put_page(page);
675         }
676         p->v = NULL;
677         return NULL;
678 }
679 
680 EXPORT_SYMBOL(read_dev_sector);
681 

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