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TOMOYO Linux Cross Reference
Linux/block/genhd.c

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  1 /*
  2  *  gendisk handling
  3  */
  4 
  5 #include <linux/module.h>
  6 #include <linux/fs.h>
  7 #include <linux/genhd.h>
  8 #include <linux/kdev_t.h>
  9 #include <linux/kernel.h>
 10 #include <linux/blkdev.h>
 11 #include <linux/backing-dev.h>
 12 #include <linux/init.h>
 13 #include <linux/spinlock.h>
 14 #include <linux/proc_fs.h>
 15 #include <linux/seq_file.h>
 16 #include <linux/slab.h>
 17 #include <linux/kmod.h>
 18 #include <linux/kobj_map.h>
 19 #include <linux/mutex.h>
 20 #include <linux/idr.h>
 21 #include <linux/log2.h>
 22 #include <linux/pm_runtime.h>
 23 #include <linux/badblocks.h>
 24 
 25 #include "blk.h"
 26 
 27 static DEFINE_MUTEX(block_class_lock);
 28 struct kobject *block_depr;
 29 
 30 /* for extended dynamic devt allocation, currently only one major is used */
 31 #define NR_EXT_DEVT             (1 << MINORBITS)
 32 
 33 /* For extended devt allocation.  ext_devt_lock prevents look up
 34  * results from going away underneath its user.
 35  */
 36 static DEFINE_SPINLOCK(ext_devt_lock);
 37 static DEFINE_IDR(ext_devt_idr);
 38 
 39 static const struct device_type disk_type;
 40 
 41 static void disk_check_events(struct disk_events *ev,
 42                               unsigned int *clearing_ptr);
 43 static void disk_alloc_events(struct gendisk *disk);
 44 static void disk_add_events(struct gendisk *disk);
 45 static void disk_del_events(struct gendisk *disk);
 46 static void disk_release_events(struct gendisk *disk);
 47 
 48 /**
 49  * disk_get_part - get partition
 50  * @disk: disk to look partition from
 51  * @partno: partition number
 52  *
 53  * Look for partition @partno from @disk.  If found, increment
 54  * reference count and return it.
 55  *
 56  * CONTEXT:
 57  * Don't care.
 58  *
 59  * RETURNS:
 60  * Pointer to the found partition on success, NULL if not found.
 61  */
 62 struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
 63 {
 64         struct hd_struct *part = NULL;
 65         struct disk_part_tbl *ptbl;
 66 
 67         if (unlikely(partno < 0))
 68                 return NULL;
 69 
 70         rcu_read_lock();
 71 
 72         ptbl = rcu_dereference(disk->part_tbl);
 73         if (likely(partno < ptbl->len)) {
 74                 part = rcu_dereference(ptbl->part[partno]);
 75                 if (part)
 76                         get_device(part_to_dev(part));
 77         }
 78 
 79         rcu_read_unlock();
 80 
 81         return part;
 82 }
 83 EXPORT_SYMBOL_GPL(disk_get_part);
 84 
 85 /**
 86  * disk_part_iter_init - initialize partition iterator
 87  * @piter: iterator to initialize
 88  * @disk: disk to iterate over
 89  * @flags: DISK_PITER_* flags
 90  *
 91  * Initialize @piter so that it iterates over partitions of @disk.
 92  *
 93  * CONTEXT:
 94  * Don't care.
 95  */
 96 void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 97                           unsigned int flags)
 98 {
 99         struct disk_part_tbl *ptbl;
100 
101         rcu_read_lock();
102         ptbl = rcu_dereference(disk->part_tbl);
103 
104         piter->disk = disk;
105         piter->part = NULL;
106 
107         if (flags & DISK_PITER_REVERSE)
108                 piter->idx = ptbl->len - 1;
109         else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
110                 piter->idx = 0;
111         else
112                 piter->idx = 1;
113 
114         piter->flags = flags;
115 
116         rcu_read_unlock();
117 }
118 EXPORT_SYMBOL_GPL(disk_part_iter_init);
119 
120 /**
121  * disk_part_iter_next - proceed iterator to the next partition and return it
122  * @piter: iterator of interest
123  *
124  * Proceed @piter to the next partition and return it.
125  *
126  * CONTEXT:
127  * Don't care.
128  */
129 struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
130 {
131         struct disk_part_tbl *ptbl;
132         int inc, end;
133 
134         /* put the last partition */
135         disk_put_part(piter->part);
136         piter->part = NULL;
137 
138         /* get part_tbl */
139         rcu_read_lock();
140         ptbl = rcu_dereference(piter->disk->part_tbl);
141 
142         /* determine iteration parameters */
143         if (piter->flags & DISK_PITER_REVERSE) {
144                 inc = -1;
145                 if (piter->flags & (DISK_PITER_INCL_PART0 |
146                                     DISK_PITER_INCL_EMPTY_PART0))
147                         end = -1;
148                 else
149                         end = 0;
150         } else {
151                 inc = 1;
152                 end = ptbl->len;
153         }
154 
155         /* iterate to the next partition */
156         for (; piter->idx != end; piter->idx += inc) {
157                 struct hd_struct *part;
158 
159                 part = rcu_dereference(ptbl->part[piter->idx]);
160                 if (!part)
161                         continue;
162                 if (!part_nr_sects_read(part) &&
163                     !(piter->flags & DISK_PITER_INCL_EMPTY) &&
164                     !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
165                       piter->idx == 0))
166                         continue;
167 
168                 get_device(part_to_dev(part));
169                 piter->part = part;
170                 piter->idx += inc;
171                 break;
172         }
173 
174         rcu_read_unlock();
175 
176         return piter->part;
177 }
178 EXPORT_SYMBOL_GPL(disk_part_iter_next);
179 
180 /**
181  * disk_part_iter_exit - finish up partition iteration
182  * @piter: iter of interest
183  *
184  * Called when iteration is over.  Cleans up @piter.
185  *
186  * CONTEXT:
187  * Don't care.
188  */
189 void disk_part_iter_exit(struct disk_part_iter *piter)
190 {
191         disk_put_part(piter->part);
192         piter->part = NULL;
193 }
194 EXPORT_SYMBOL_GPL(disk_part_iter_exit);
195 
196 static inline int sector_in_part(struct hd_struct *part, sector_t sector)
197 {
198         return part->start_sect <= sector &&
199                 sector < part->start_sect + part_nr_sects_read(part);
200 }
201 
202 /**
203  * disk_map_sector_rcu - map sector to partition
204  * @disk: gendisk of interest
205  * @sector: sector to map
206  *
207  * Find out which partition @sector maps to on @disk.  This is
208  * primarily used for stats accounting.
209  *
210  * CONTEXT:
211  * RCU read locked.  The returned partition pointer is valid only
212  * while preemption is disabled.
213  *
214  * RETURNS:
215  * Found partition on success, part0 is returned if no partition matches
216  */
217 struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
218 {
219         struct disk_part_tbl *ptbl;
220         struct hd_struct *part;
221         int i;
222 
223         ptbl = rcu_dereference(disk->part_tbl);
224 
225         part = rcu_dereference(ptbl->last_lookup);
226         if (part && sector_in_part(part, sector))
227                 return part;
228 
229         for (i = 1; i < ptbl->len; i++) {
230                 part = rcu_dereference(ptbl->part[i]);
231 
232                 if (part && sector_in_part(part, sector)) {
233                         rcu_assign_pointer(ptbl->last_lookup, part);
234                         return part;
235                 }
236         }
237         return &disk->part0;
238 }
239 EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
240 
241 /*
242  * Can be deleted altogether. Later.
243  *
244  */
245 static struct blk_major_name {
246         struct blk_major_name *next;
247         int major;
248         char name[16];
249 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
250 
251 /* index in the above - for now: assume no multimajor ranges */
252 static inline int major_to_index(unsigned major)
253 {
254         return major % BLKDEV_MAJOR_HASH_SIZE;
255 }
256 
257 #ifdef CONFIG_PROC_FS
258 void blkdev_show(struct seq_file *seqf, off_t offset)
259 {
260         struct blk_major_name *dp;
261 
262         if (offset < BLKDEV_MAJOR_HASH_SIZE) {
263                 mutex_lock(&block_class_lock);
264                 for (dp = major_names[offset]; dp; dp = dp->next)
265                         seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
266                 mutex_unlock(&block_class_lock);
267         }
268 }
269 #endif /* CONFIG_PROC_FS */
270 
271 /**
272  * register_blkdev - register a new block device
273  *
274  * @major: the requested major device number [1..255]. If @major = 0, try to
275  *         allocate any unused major number.
276  * @name: the name of the new block device as a zero terminated string
277  *
278  * The @name must be unique within the system.
279  *
280  * The return value depends on the @major input parameter:
281  *
282  *  - if a major device number was requested in range [1..255] then the
283  *    function returns zero on success, or a negative error code
284  *  - if any unused major number was requested with @major = 0 parameter
285  *    then the return value is the allocated major number in range
286  *    [1..255] or a negative error code otherwise
287  */
288 int register_blkdev(unsigned int major, const char *name)
289 {
290         struct blk_major_name **n, *p;
291         int index, ret = 0;
292 
293         mutex_lock(&block_class_lock);
294 
295         /* temporary */
296         if (major == 0) {
297                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
298                         if (major_names[index] == NULL)
299                                 break;
300                 }
301 
302                 if (index == 0) {
303                         printk("register_blkdev: failed to get major for %s\n",
304                                name);
305                         ret = -EBUSY;
306                         goto out;
307                 }
308                 major = index;
309                 ret = major;
310         }
311 
312         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
313         if (p == NULL) {
314                 ret = -ENOMEM;
315                 goto out;
316         }
317 
318         p->major = major;
319         strlcpy(p->name, name, sizeof(p->name));
320         p->next = NULL;
321         index = major_to_index(major);
322 
323         for (n = &major_names[index]; *n; n = &(*n)->next) {
324                 if ((*n)->major == major)
325                         break;
326         }
327         if (!*n)
328                 *n = p;
329         else
330                 ret = -EBUSY;
331 
332         if (ret < 0) {
333                 printk("register_blkdev: cannot get major %d for %s\n",
334                        major, name);
335                 kfree(p);
336         }
337 out:
338         mutex_unlock(&block_class_lock);
339         return ret;
340 }
341 
342 EXPORT_SYMBOL(register_blkdev);
343 
344 void unregister_blkdev(unsigned int major, const char *name)
345 {
346         struct blk_major_name **n;
347         struct blk_major_name *p = NULL;
348         int index = major_to_index(major);
349 
350         mutex_lock(&block_class_lock);
351         for (n = &major_names[index]; *n; n = &(*n)->next)
352                 if ((*n)->major == major)
353                         break;
354         if (!*n || strcmp((*n)->name, name)) {
355                 WARN_ON(1);
356         } else {
357                 p = *n;
358                 *n = p->next;
359         }
360         mutex_unlock(&block_class_lock);
361         kfree(p);
362 }
363 
364 EXPORT_SYMBOL(unregister_blkdev);
365 
366 static struct kobj_map *bdev_map;
367 
368 /**
369  * blk_mangle_minor - scatter minor numbers apart
370  * @minor: minor number to mangle
371  *
372  * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
373  * is enabled.  Mangling twice gives the original value.
374  *
375  * RETURNS:
376  * Mangled value.
377  *
378  * CONTEXT:
379  * Don't care.
380  */
381 static int blk_mangle_minor(int minor)
382 {
383 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
384         int i;
385 
386         for (i = 0; i < MINORBITS / 2; i++) {
387                 int low = minor & (1 << i);
388                 int high = minor & (1 << (MINORBITS - 1 - i));
389                 int distance = MINORBITS - 1 - 2 * i;
390 
391                 minor ^= low | high;    /* clear both bits */
392                 low <<= distance;       /* swap the positions */
393                 high >>= distance;
394                 minor |= low | high;    /* and set */
395         }
396 #endif
397         return minor;
398 }
399 
400 /**
401  * blk_alloc_devt - allocate a dev_t for a partition
402  * @part: partition to allocate dev_t for
403  * @devt: out parameter for resulting dev_t
404  *
405  * Allocate a dev_t for block device.
406  *
407  * RETURNS:
408  * 0 on success, allocated dev_t is returned in *@devt.  -errno on
409  * failure.
410  *
411  * CONTEXT:
412  * Might sleep.
413  */
414 int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
415 {
416         struct gendisk *disk = part_to_disk(part);
417         int idx;
418 
419         /* in consecutive minor range? */
420         if (part->partno < disk->minors) {
421                 *devt = MKDEV(disk->major, disk->first_minor + part->partno);
422                 return 0;
423         }
424 
425         /* allocate ext devt */
426         idr_preload(GFP_KERNEL);
427 
428         spin_lock_bh(&ext_devt_lock);
429         idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);
430         spin_unlock_bh(&ext_devt_lock);
431 
432         idr_preload_end();
433         if (idx < 0)
434                 return idx == -ENOSPC ? -EBUSY : idx;
435 
436         *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
437         return 0;
438 }
439 
440 /**
441  * blk_free_devt - free a dev_t
442  * @devt: dev_t to free
443  *
444  * Free @devt which was allocated using blk_alloc_devt().
445  *
446  * CONTEXT:
447  * Might sleep.
448  */
449 void blk_free_devt(dev_t devt)
450 {
451         if (devt == MKDEV(0, 0))
452                 return;
453 
454         if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
455                 spin_lock_bh(&ext_devt_lock);
456                 idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
457                 spin_unlock_bh(&ext_devt_lock);
458         }
459 }
460 
461 static char *bdevt_str(dev_t devt, char *buf)
462 {
463         if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
464                 char tbuf[BDEVT_SIZE];
465                 snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
466                 snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
467         } else
468                 snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
469 
470         return buf;
471 }
472 
473 /*
474  * Register device numbers dev..(dev+range-1)
475  * range must be nonzero
476  * The hash chain is sorted on range, so that subranges can override.
477  */
478 void blk_register_region(dev_t devt, unsigned long range, struct module *module,
479                          struct kobject *(*probe)(dev_t, int *, void *),
480                          int (*lock)(dev_t, void *), void *data)
481 {
482         kobj_map(bdev_map, devt, range, module, probe, lock, data);
483 }
484 
485 EXPORT_SYMBOL(blk_register_region);
486 
487 void blk_unregister_region(dev_t devt, unsigned long range)
488 {
489         kobj_unmap(bdev_map, devt, range);
490 }
491 
492 EXPORT_SYMBOL(blk_unregister_region);
493 
494 static struct kobject *exact_match(dev_t devt, int *partno, void *data)
495 {
496         struct gendisk *p = data;
497 
498         return &disk_to_dev(p)->kobj;
499 }
500 
501 static int exact_lock(dev_t devt, void *data)
502 {
503         struct gendisk *p = data;
504 
505         if (!get_disk(p))
506                 return -1;
507         return 0;
508 }
509 
510 static void register_disk(struct device *parent, struct gendisk *disk)
511 {
512         struct device *ddev = disk_to_dev(disk);
513         struct block_device *bdev;
514         struct disk_part_iter piter;
515         struct hd_struct *part;
516         int err;
517 
518         ddev->parent = parent;
519 
520         dev_set_name(ddev, "%s", disk->disk_name);
521 
522         /* delay uevents, until we scanned partition table */
523         dev_set_uevent_suppress(ddev, 1);
524 
525         if (device_add(ddev))
526                 return;
527         if (!sysfs_deprecated) {
528                 err = sysfs_create_link(block_depr, &ddev->kobj,
529                                         kobject_name(&ddev->kobj));
530                 if (err) {
531                         device_del(ddev);
532                         return;
533                 }
534         }
535 
536         /*
537          * avoid probable deadlock caused by allocating memory with
538          * GFP_KERNEL in runtime_resume callback of its all ancestor
539          * devices
540          */
541         pm_runtime_set_memalloc_noio(ddev, true);
542 
543         disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
544         disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
545 
546         /* No minors to use for partitions */
547         if (!disk_part_scan_enabled(disk))
548                 goto exit;
549 
550         /* No such device (e.g., media were just removed) */
551         if (!get_capacity(disk))
552                 goto exit;
553 
554         bdev = bdget_disk(disk, 0);
555         if (!bdev)
556                 goto exit;
557 
558         bdev->bd_invalidated = 1;
559         err = blkdev_get(bdev, FMODE_READ, NULL);
560         if (err < 0)
561                 goto exit;
562         blkdev_put(bdev, FMODE_READ);
563 
564 exit:
565         /* announce disk after possible partitions are created */
566         dev_set_uevent_suppress(ddev, 0);
567         kobject_uevent(&ddev->kobj, KOBJ_ADD);
568 
569         /* announce possible partitions */
570         disk_part_iter_init(&piter, disk, 0);
571         while ((part = disk_part_iter_next(&piter)))
572                 kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
573         disk_part_iter_exit(&piter);
574 }
575 
576 /**
577  * device_add_disk - add partitioning information to kernel list
578  * @parent: parent device for the disk
579  * @disk: per-device partitioning information
580  *
581  * This function registers the partitioning information in @disk
582  * with the kernel.
583  *
584  * FIXME: error handling
585  */
586 void device_add_disk(struct device *parent, struct gendisk *disk)
587 {
588         struct backing_dev_info *bdi;
589         dev_t devt;
590         int retval;
591 
592         /* minors == 0 indicates to use ext devt from part0 and should
593          * be accompanied with EXT_DEVT flag.  Make sure all
594          * parameters make sense.
595          */
596         WARN_ON(disk->minors && !(disk->major || disk->first_minor));
597         WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
598 
599         disk->flags |= GENHD_FL_UP;
600 
601         retval = blk_alloc_devt(&disk->part0, &devt);
602         if (retval) {
603                 WARN_ON(1);
604                 return;
605         }
606         disk_to_dev(disk)->devt = devt;
607 
608         /* ->major and ->first_minor aren't supposed to be
609          * dereferenced from here on, but set them just in case.
610          */
611         disk->major = MAJOR(devt);
612         disk->first_minor = MINOR(devt);
613 
614         disk_alloc_events(disk);
615 
616         /* Register BDI before referencing it from bdev */
617         bdi = disk->queue->backing_dev_info;
618         bdi_register_owner(bdi, disk_to_dev(disk));
619 
620         blk_register_region(disk_devt(disk), disk->minors, NULL,
621                             exact_match, exact_lock, disk);
622         register_disk(parent, disk);
623         blk_register_queue(disk);
624 
625         /*
626          * Take an extra ref on queue which will be put on disk_release()
627          * so that it sticks around as long as @disk is there.
628          */
629         WARN_ON_ONCE(!blk_get_queue(disk->queue));
630 
631         retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
632                                    "bdi");
633         WARN_ON(retval);
634 
635         disk_add_events(disk);
636         blk_integrity_add(disk);
637 }
638 EXPORT_SYMBOL(device_add_disk);
639 
640 void del_gendisk(struct gendisk *disk)
641 {
642         struct disk_part_iter piter;
643         struct hd_struct *part;
644 
645         blk_integrity_del(disk);
646         disk_del_events(disk);
647 
648         /* invalidate stuff */
649         disk_part_iter_init(&piter, disk,
650                              DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
651         while ((part = disk_part_iter_next(&piter))) {
652                 invalidate_partition(disk, part->partno);
653                 bdev_unhash_inode(part_devt(part));
654                 delete_partition(disk, part->partno);
655         }
656         disk_part_iter_exit(&piter);
657 
658         invalidate_partition(disk, 0);
659         bdev_unhash_inode(disk_devt(disk));
660         set_capacity(disk, 0);
661         disk->flags &= ~GENHD_FL_UP;
662 
663         sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
664         if (disk->queue) {
665                 /*
666                  * Unregister bdi before releasing device numbers (as they can
667                  * get reused and we'd get clashes in sysfs).
668                  */
669                 bdi_unregister(disk->queue->backing_dev_info);
670                 blk_unregister_queue(disk);
671         } else {
672                 WARN_ON(1);
673         }
674         blk_unregister_region(disk_devt(disk), disk->minors);
675 
676         part_stat_set_all(&disk->part0, 0);
677         disk->part0.stamp = 0;
678 
679         kobject_put(disk->part0.holder_dir);
680         kobject_put(disk->slave_dir);
681         if (!sysfs_deprecated)
682                 sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
683         pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
684         device_del(disk_to_dev(disk));
685 }
686 EXPORT_SYMBOL(del_gendisk);
687 
688 /* sysfs access to bad-blocks list. */
689 static ssize_t disk_badblocks_show(struct device *dev,
690                                         struct device_attribute *attr,
691                                         char *page)
692 {
693         struct gendisk *disk = dev_to_disk(dev);
694 
695         if (!disk->bb)
696                 return sprintf(page, "\n");
697 
698         return badblocks_show(disk->bb, page, 0);
699 }
700 
701 static ssize_t disk_badblocks_store(struct device *dev,
702                                         struct device_attribute *attr,
703                                         const char *page, size_t len)
704 {
705         struct gendisk *disk = dev_to_disk(dev);
706 
707         if (!disk->bb)
708                 return -ENXIO;
709 
710         return badblocks_store(disk->bb, page, len, 0);
711 }
712 
713 /**
714  * get_gendisk - get partitioning information for a given device
715  * @devt: device to get partitioning information for
716  * @partno: returned partition index
717  *
718  * This function gets the structure containing partitioning
719  * information for the given device @devt.
720  */
721 struct gendisk *get_gendisk(dev_t devt, int *partno)
722 {
723         struct gendisk *disk = NULL;
724 
725         if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
726                 struct kobject *kobj;
727 
728                 kobj = kobj_lookup(bdev_map, devt, partno);
729                 if (kobj)
730                         disk = dev_to_disk(kobj_to_dev(kobj));
731         } else {
732                 struct hd_struct *part;
733 
734                 spin_lock_bh(&ext_devt_lock);
735                 part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
736                 if (part && get_disk(part_to_disk(part))) {
737                         *partno = part->partno;
738                         disk = part_to_disk(part);
739                 }
740                 spin_unlock_bh(&ext_devt_lock);
741         }
742 
743         return disk;
744 }
745 EXPORT_SYMBOL(get_gendisk);
746 
747 /**
748  * bdget_disk - do bdget() by gendisk and partition number
749  * @disk: gendisk of interest
750  * @partno: partition number
751  *
752  * Find partition @partno from @disk, do bdget() on it.
753  *
754  * CONTEXT:
755  * Don't care.
756  *
757  * RETURNS:
758  * Resulting block_device on success, NULL on failure.
759  */
760 struct block_device *bdget_disk(struct gendisk *disk, int partno)
761 {
762         struct hd_struct *part;
763         struct block_device *bdev = NULL;
764 
765         part = disk_get_part(disk, partno);
766         if (part)
767                 bdev = bdget(part_devt(part));
768         disk_put_part(part);
769 
770         return bdev;
771 }
772 EXPORT_SYMBOL(bdget_disk);
773 
774 /*
775  * print a full list of all partitions - intended for places where the root
776  * filesystem can't be mounted and thus to give the victim some idea of what
777  * went wrong
778  */
779 void __init printk_all_partitions(void)
780 {
781         struct class_dev_iter iter;
782         struct device *dev;
783 
784         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
785         while ((dev = class_dev_iter_next(&iter))) {
786                 struct gendisk *disk = dev_to_disk(dev);
787                 struct disk_part_iter piter;
788                 struct hd_struct *part;
789                 char name_buf[BDEVNAME_SIZE];
790                 char devt_buf[BDEVT_SIZE];
791 
792                 /*
793                  * Don't show empty devices or things that have been
794                  * suppressed
795                  */
796                 if (get_capacity(disk) == 0 ||
797                     (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
798                         continue;
799 
800                 /*
801                  * Note, unlike /proc/partitions, I am showing the
802                  * numbers in hex - the same format as the root=
803                  * option takes.
804                  */
805                 disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
806                 while ((part = disk_part_iter_next(&piter))) {
807                         bool is_part0 = part == &disk->part0;
808 
809                         printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
810                                bdevt_str(part_devt(part), devt_buf),
811                                (unsigned long long)part_nr_sects_read(part) >> 1
812                                , disk_name(disk, part->partno, name_buf),
813                                part->info ? part->info->uuid : "");
814                         if (is_part0) {
815                                 if (dev->parent && dev->parent->driver)
816                                         printk(" driver: %s\n",
817                                               dev->parent->driver->name);
818                                 else
819                                         printk(" (driver?)\n");
820                         } else
821                                 printk("\n");
822                 }
823                 disk_part_iter_exit(&piter);
824         }
825         class_dev_iter_exit(&iter);
826 }
827 
828 #ifdef CONFIG_PROC_FS
829 /* iterator */
830 static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
831 {
832         loff_t skip = *pos;
833         struct class_dev_iter *iter;
834         struct device *dev;
835 
836         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
837         if (!iter)
838                 return ERR_PTR(-ENOMEM);
839 
840         seqf->private = iter;
841         class_dev_iter_init(iter, &block_class, NULL, &disk_type);
842         do {
843                 dev = class_dev_iter_next(iter);
844                 if (!dev)
845                         return NULL;
846         } while (skip--);
847 
848         return dev_to_disk(dev);
849 }
850 
851 static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
852 {
853         struct device *dev;
854 
855         (*pos)++;
856         dev = class_dev_iter_next(seqf->private);
857         if (dev)
858                 return dev_to_disk(dev);
859 
860         return NULL;
861 }
862 
863 static void disk_seqf_stop(struct seq_file *seqf, void *v)
864 {
865         struct class_dev_iter *iter = seqf->private;
866 
867         /* stop is called even after start failed :-( */
868         if (iter) {
869                 class_dev_iter_exit(iter);
870                 kfree(iter);
871                 seqf->private = NULL;
872         }
873 }
874 
875 static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
876 {
877         void *p;
878 
879         p = disk_seqf_start(seqf, pos);
880         if (!IS_ERR_OR_NULL(p) && !*pos)
881                 seq_puts(seqf, "major minor  #blocks  name\n\n");
882         return p;
883 }
884 
885 static int show_partition(struct seq_file *seqf, void *v)
886 {
887         struct gendisk *sgp = v;
888         struct disk_part_iter piter;
889         struct hd_struct *part;
890         char buf[BDEVNAME_SIZE];
891 
892         /* Don't show non-partitionable removeable devices or empty devices */
893         if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
894                                    (sgp->flags & GENHD_FL_REMOVABLE)))
895                 return 0;
896         if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
897                 return 0;
898 
899         /* show the full disk and all non-0 size partitions of it */
900         disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
901         while ((part = disk_part_iter_next(&piter)))
902                 seq_printf(seqf, "%4d  %7d %10llu %s\n",
903                            MAJOR(part_devt(part)), MINOR(part_devt(part)),
904                            (unsigned long long)part_nr_sects_read(part) >> 1,
905                            disk_name(sgp, part->partno, buf));
906         disk_part_iter_exit(&piter);
907 
908         return 0;
909 }
910 
911 static const struct seq_operations partitions_op = {
912         .start  = show_partition_start,
913         .next   = disk_seqf_next,
914         .stop   = disk_seqf_stop,
915         .show   = show_partition
916 };
917 
918 static int partitions_open(struct inode *inode, struct file *file)
919 {
920         return seq_open(file, &partitions_op);
921 }
922 
923 static const struct file_operations proc_partitions_operations = {
924         .open           = partitions_open,
925         .read           = seq_read,
926         .llseek         = seq_lseek,
927         .release        = seq_release,
928 };
929 #endif
930 
931 
932 static struct kobject *base_probe(dev_t devt, int *partno, void *data)
933 {
934         if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
935                 /* Make old-style 2.4 aliases work */
936                 request_module("block-major-%d", MAJOR(devt));
937         return NULL;
938 }
939 
940 static int __init genhd_device_init(void)
941 {
942         int error;
943 
944         block_class.dev_kobj = sysfs_dev_block_kobj;
945         error = class_register(&block_class);
946         if (unlikely(error))
947                 return error;
948         bdev_map = kobj_map_init(base_probe, &block_class_lock);
949         blk_dev_init();
950 
951         register_blkdev(BLOCK_EXT_MAJOR, "blkext");
952 
953         /* create top-level block dir */
954         if (!sysfs_deprecated)
955                 block_depr = kobject_create_and_add("block", NULL);
956         return 0;
957 }
958 
959 subsys_initcall(genhd_device_init);
960 
961 static ssize_t disk_range_show(struct device *dev,
962                                struct device_attribute *attr, char *buf)
963 {
964         struct gendisk *disk = dev_to_disk(dev);
965 
966         return sprintf(buf, "%d\n", disk->minors);
967 }
968 
969 static ssize_t disk_ext_range_show(struct device *dev,
970                                    struct device_attribute *attr, char *buf)
971 {
972         struct gendisk *disk = dev_to_disk(dev);
973 
974         return sprintf(buf, "%d\n", disk_max_parts(disk));
975 }
976 
977 static ssize_t disk_removable_show(struct device *dev,
978                                    struct device_attribute *attr, char *buf)
979 {
980         struct gendisk *disk = dev_to_disk(dev);
981 
982         return sprintf(buf, "%d\n",
983                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
984 }
985 
986 static ssize_t disk_ro_show(struct device *dev,
987                                    struct device_attribute *attr, char *buf)
988 {
989         struct gendisk *disk = dev_to_disk(dev);
990 
991         return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
992 }
993 
994 static ssize_t disk_capability_show(struct device *dev,
995                                     struct device_attribute *attr, char *buf)
996 {
997         struct gendisk *disk = dev_to_disk(dev);
998 
999         return sprintf(buf, "%x\n", disk->flags);
1000 }
1001 
1002 static ssize_t disk_alignment_offset_show(struct device *dev,
1003                                           struct device_attribute *attr,
1004                                           char *buf)
1005 {
1006         struct gendisk *disk = dev_to_disk(dev);
1007 
1008         return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
1009 }
1010 
1011 static ssize_t disk_discard_alignment_show(struct device *dev,
1012                                            struct device_attribute *attr,
1013                                            char *buf)
1014 {
1015         struct gendisk *disk = dev_to_disk(dev);
1016 
1017         return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));
1018 }
1019 
1020 static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
1021 static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
1022 static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
1023 static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
1024 static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
1025 static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
1026 static DEVICE_ATTR(discard_alignment, S_IRUGO, disk_discard_alignment_show,
1027                    NULL);
1028 static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
1029 static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
1030 static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
1031 static DEVICE_ATTR(badblocks, S_IRUGO | S_IWUSR, disk_badblocks_show,
1032                 disk_badblocks_store);
1033 #ifdef CONFIG_FAIL_MAKE_REQUEST
1034 static struct device_attribute dev_attr_fail =
1035         __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
1036 #endif
1037 #ifdef CONFIG_FAIL_IO_TIMEOUT
1038 static struct device_attribute dev_attr_fail_timeout =
1039         __ATTR(io-timeout-fail,  S_IRUGO|S_IWUSR, part_timeout_show,
1040                 part_timeout_store);
1041 #endif
1042 
1043 static struct attribute *disk_attrs[] = {
1044         &dev_attr_range.attr,
1045         &dev_attr_ext_range.attr,
1046         &dev_attr_removable.attr,
1047         &dev_attr_ro.attr,
1048         &dev_attr_size.attr,
1049         &dev_attr_alignment_offset.attr,
1050         &dev_attr_discard_alignment.attr,
1051         &dev_attr_capability.attr,
1052         &dev_attr_stat.attr,
1053         &dev_attr_inflight.attr,
1054         &dev_attr_badblocks.attr,
1055 #ifdef CONFIG_FAIL_MAKE_REQUEST
1056         &dev_attr_fail.attr,
1057 #endif
1058 #ifdef CONFIG_FAIL_IO_TIMEOUT
1059         &dev_attr_fail_timeout.attr,
1060 #endif
1061         NULL
1062 };
1063 
1064 static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)
1065 {
1066         struct device *dev = container_of(kobj, typeof(*dev), kobj);
1067         struct gendisk *disk = dev_to_disk(dev);
1068 
1069         if (a == &dev_attr_badblocks.attr && !disk->bb)
1070                 return 0;
1071         return a->mode;
1072 }
1073 
1074 static struct attribute_group disk_attr_group = {
1075         .attrs = disk_attrs,
1076         .is_visible = disk_visible,
1077 };
1078 
1079 static const struct attribute_group *disk_attr_groups[] = {
1080         &disk_attr_group,
1081         NULL
1082 };
1083 
1084 /**
1085  * disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
1086  * @disk: disk to replace part_tbl for
1087  * @new_ptbl: new part_tbl to install
1088  *
1089  * Replace disk->part_tbl with @new_ptbl in RCU-safe way.  The
1090  * original ptbl is freed using RCU callback.
1091  *
1092  * LOCKING:
1093  * Matching bd_mutx locked.
1094  */
1095 static void disk_replace_part_tbl(struct gendisk *disk,
1096                                   struct disk_part_tbl *new_ptbl)
1097 {
1098         struct disk_part_tbl *old_ptbl = disk->part_tbl;
1099 
1100         rcu_assign_pointer(disk->part_tbl, new_ptbl);
1101 
1102         if (old_ptbl) {
1103                 rcu_assign_pointer(old_ptbl->last_lookup, NULL);
1104                 kfree_rcu(old_ptbl, rcu_head);
1105         }
1106 }
1107 
1108 /**
1109  * disk_expand_part_tbl - expand disk->part_tbl
1110  * @disk: disk to expand part_tbl for
1111  * @partno: expand such that this partno can fit in
1112  *
1113  * Expand disk->part_tbl such that @partno can fit in.  disk->part_tbl
1114  * uses RCU to allow unlocked dereferencing for stats and other stuff.
1115  *
1116  * LOCKING:
1117  * Matching bd_mutex locked, might sleep.
1118  *
1119  * RETURNS:
1120  * 0 on success, -errno on failure.
1121  */
1122 int disk_expand_part_tbl(struct gendisk *disk, int partno)
1123 {
1124         struct disk_part_tbl *old_ptbl = disk->part_tbl;
1125         struct disk_part_tbl *new_ptbl;
1126         int len = old_ptbl ? old_ptbl->len : 0;
1127         int i, target;
1128         size_t size;
1129 
1130         /*
1131          * check for int overflow, since we can get here from blkpg_ioctl()
1132          * with a user passed 'partno'.
1133          */
1134         target = partno + 1;
1135         if (target < 0)
1136                 return -EINVAL;
1137 
1138         /* disk_max_parts() is zero during initialization, ignore if so */
1139         if (disk_max_parts(disk) && target > disk_max_parts(disk))
1140                 return -EINVAL;
1141 
1142         if (target <= len)
1143                 return 0;
1144 
1145         size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
1146         new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
1147         if (!new_ptbl)
1148                 return -ENOMEM;
1149 
1150         new_ptbl->len = target;
1151 
1152         for (i = 0; i < len; i++)
1153                 rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
1154 
1155         disk_replace_part_tbl(disk, new_ptbl);
1156         return 0;
1157 }
1158 
1159 static void disk_release(struct device *dev)
1160 {
1161         struct gendisk *disk = dev_to_disk(dev);
1162 
1163         blk_free_devt(dev->devt);
1164         disk_release_events(disk);
1165         kfree(disk->random);
1166         disk_replace_part_tbl(disk, NULL);
1167         hd_free_part(&disk->part0);
1168         if (disk->queue)
1169                 blk_put_queue(disk->queue);
1170         kfree(disk);
1171 }
1172 struct class block_class = {
1173         .name           = "block",
1174 };
1175 
1176 static char *block_devnode(struct device *dev, umode_t *mode,
1177                            kuid_t *uid, kgid_t *gid)
1178 {
1179         struct gendisk *disk = dev_to_disk(dev);
1180 
1181         if (disk->devnode)
1182                 return disk->devnode(disk, mode);
1183         return NULL;
1184 }
1185 
1186 static const struct device_type disk_type = {
1187         .name           = "disk",
1188         .groups         = disk_attr_groups,
1189         .release        = disk_release,
1190         .devnode        = block_devnode,
1191 };
1192 
1193 #ifdef CONFIG_PROC_FS
1194 /*
1195  * aggregate disk stat collector.  Uses the same stats that the sysfs
1196  * entries do, above, but makes them available through one seq_file.
1197  *
1198  * The output looks suspiciously like /proc/partitions with a bunch of
1199  * extra fields.
1200  */
1201 static int diskstats_show(struct seq_file *seqf, void *v)
1202 {
1203         struct gendisk *gp = v;
1204         struct disk_part_iter piter;
1205         struct hd_struct *hd;
1206         char buf[BDEVNAME_SIZE];
1207         int cpu;
1208 
1209         /*
1210         if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
1211                 seq_puts(seqf,  "major minor name"
1212                                 "     rio rmerge rsect ruse wio wmerge "
1213                                 "wsect wuse running use aveq"
1214                                 "\n\n");
1215         */
1216 
1217         disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
1218         while ((hd = disk_part_iter_next(&piter))) {
1219                 cpu = part_stat_lock();
1220                 part_round_stats(cpu, hd);
1221                 part_stat_unlock();
1222                 seq_printf(seqf, "%4d %7d %s %lu %lu %lu "
1223                            "%u %lu %lu %lu %u %u %u %u\n",
1224                            MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
1225                            disk_name(gp, hd->partno, buf),
1226                            part_stat_read(hd, ios[READ]),
1227                            part_stat_read(hd, merges[READ]),
1228                            part_stat_read(hd, sectors[READ]),
1229                            jiffies_to_msecs(part_stat_read(hd, ticks[READ])),
1230                            part_stat_read(hd, ios[WRITE]),
1231                            part_stat_read(hd, merges[WRITE]),
1232                            part_stat_read(hd, sectors[WRITE]),
1233                            jiffies_to_msecs(part_stat_read(hd, ticks[WRITE])),
1234                            part_in_flight(hd),
1235                            jiffies_to_msecs(part_stat_read(hd, io_ticks)),
1236                            jiffies_to_msecs(part_stat_read(hd, time_in_queue))
1237                         );
1238         }
1239         disk_part_iter_exit(&piter);
1240 
1241         return 0;
1242 }
1243 
1244 static const struct seq_operations diskstats_op = {
1245         .start  = disk_seqf_start,
1246         .next   = disk_seqf_next,
1247         .stop   = disk_seqf_stop,
1248         .show   = diskstats_show
1249 };
1250 
1251 static int diskstats_open(struct inode *inode, struct file *file)
1252 {
1253         return seq_open(file, &diskstats_op);
1254 }
1255 
1256 static const struct file_operations proc_diskstats_operations = {
1257         .open           = diskstats_open,
1258         .read           = seq_read,
1259         .llseek         = seq_lseek,
1260         .release        = seq_release,
1261 };
1262 
1263 static int __init proc_genhd_init(void)
1264 {
1265         proc_create("diskstats", 0, NULL, &proc_diskstats_operations);
1266         proc_create("partitions", 0, NULL, &proc_partitions_operations);
1267         return 0;
1268 }
1269 module_init(proc_genhd_init);
1270 #endif /* CONFIG_PROC_FS */
1271 
1272 dev_t blk_lookup_devt(const char *name, int partno)
1273 {
1274         dev_t devt = MKDEV(0, 0);
1275         struct class_dev_iter iter;
1276         struct device *dev;
1277 
1278         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
1279         while ((dev = class_dev_iter_next(&iter))) {
1280                 struct gendisk *disk = dev_to_disk(dev);
1281                 struct hd_struct *part;
1282 
1283                 if (strcmp(dev_name(dev), name))
1284                         continue;
1285 
1286                 if (partno < disk->minors) {
1287                         /* We need to return the right devno, even
1288                          * if the partition doesn't exist yet.
1289                          */
1290                         devt = MKDEV(MAJOR(dev->devt),
1291                                      MINOR(dev->devt) + partno);
1292                         break;
1293                 }
1294                 part = disk_get_part(disk, partno);
1295                 if (part) {
1296                         devt = part_devt(part);
1297                         disk_put_part(part);
1298                         break;
1299                 }
1300                 disk_put_part(part);
1301         }
1302         class_dev_iter_exit(&iter);
1303         return devt;
1304 }
1305 EXPORT_SYMBOL(blk_lookup_devt);
1306 
1307 struct gendisk *alloc_disk(int minors)
1308 {
1309         return alloc_disk_node(minors, NUMA_NO_NODE);
1310 }
1311 EXPORT_SYMBOL(alloc_disk);
1312 
1313 struct gendisk *alloc_disk_node(int minors, int node_id)
1314 {
1315         struct gendisk *disk;
1316 
1317         disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
1318         if (disk) {
1319                 if (!init_part_stats(&disk->part0)) {
1320                         kfree(disk);
1321                         return NULL;
1322                 }
1323                 disk->node_id = node_id;
1324                 if (disk_expand_part_tbl(disk, 0)) {
1325                         free_part_stats(&disk->part0);
1326                         kfree(disk);
1327                         return NULL;
1328                 }
1329                 disk->part_tbl->part[0] = &disk->part0;
1330 
1331                 /*
1332                  * set_capacity() and get_capacity() currently don't use
1333                  * seqcounter to read/update the part0->nr_sects. Still init
1334                  * the counter as we can read the sectors in IO submission
1335                  * patch using seqence counters.
1336                  *
1337                  * TODO: Ideally set_capacity() and get_capacity() should be
1338                  * converted to make use of bd_mutex and sequence counters.
1339                  */
1340                 seqcount_init(&disk->part0.nr_sects_seq);
1341                 if (hd_ref_init(&disk->part0)) {
1342                         hd_free_part(&disk->part0);
1343                         kfree(disk);
1344                         return NULL;
1345                 }
1346 
1347                 disk->minors = minors;
1348                 rand_initialize_disk(disk);
1349                 disk_to_dev(disk)->class = &block_class;
1350                 disk_to_dev(disk)->type = &disk_type;
1351                 device_initialize(disk_to_dev(disk));
1352         }
1353         return disk;
1354 }
1355 EXPORT_SYMBOL(alloc_disk_node);
1356 
1357 struct kobject *get_disk(struct gendisk *disk)
1358 {
1359         struct module *owner;
1360         struct kobject *kobj;
1361 
1362         if (!disk->fops)
1363                 return NULL;
1364         owner = disk->fops->owner;
1365         if (owner && !try_module_get(owner))
1366                 return NULL;
1367         kobj = kobject_get_unless_zero(&disk_to_dev(disk)->kobj);
1368         if (kobj == NULL) {
1369                 module_put(owner);
1370                 return NULL;
1371         }
1372         return kobj;
1373 
1374 }
1375 
1376 EXPORT_SYMBOL(get_disk);
1377 
1378 void put_disk(struct gendisk *disk)
1379 {
1380         if (disk)
1381                 kobject_put(&disk_to_dev(disk)->kobj);
1382 }
1383 
1384 EXPORT_SYMBOL(put_disk);
1385 
1386 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
1387 {
1388         char event[] = "DISK_RO=1";
1389         char *envp[] = { event, NULL };
1390 
1391         if (!ro)
1392                 event[8] = '';
1393         kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
1394 }
1395 
1396 void set_device_ro(struct block_device *bdev, int flag)
1397 {
1398         bdev->bd_part->policy = flag;
1399 }
1400 
1401 EXPORT_SYMBOL(set_device_ro);
1402 
1403 void set_disk_ro(struct gendisk *disk, int flag)
1404 {
1405         struct disk_part_iter piter;
1406         struct hd_struct *part;
1407 
1408         if (disk->part0.policy != flag) {
1409                 set_disk_ro_uevent(disk, flag);
1410                 disk->part0.policy = flag;
1411         }
1412 
1413         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
1414         while ((part = disk_part_iter_next(&piter)))
1415                 part->policy = flag;
1416         disk_part_iter_exit(&piter);
1417 }
1418 
1419 EXPORT_SYMBOL(set_disk_ro);
1420 
1421 int bdev_read_only(struct block_device *bdev)
1422 {
1423         if (!bdev)
1424                 return 0;
1425         return bdev->bd_part->policy;
1426 }
1427 
1428 EXPORT_SYMBOL(bdev_read_only);
1429 
1430 int invalidate_partition(struct gendisk *disk, int partno)
1431 {
1432         int res = 0;
1433         struct block_device *bdev = bdget_disk(disk, partno);
1434         if (bdev) {
1435                 fsync_bdev(bdev);
1436                 res = __invalidate_device(bdev, true);
1437                 bdput(bdev);
1438         }
1439         return res;
1440 }
1441 
1442 EXPORT_SYMBOL(invalidate_partition);
1443 
1444 /*
1445  * Disk events - monitor disk events like media change and eject request.
1446  */
1447 struct disk_events {
1448         struct list_head        node;           /* all disk_event's */
1449         struct gendisk          *disk;          /* the associated disk */
1450         spinlock_t              lock;
1451 
1452         struct mutex            block_mutex;    /* protects blocking */
1453         int                     block;          /* event blocking depth */
1454         unsigned int            pending;        /* events already sent out */
1455         unsigned int            clearing;       /* events being cleared */
1456 
1457         long                    poll_msecs;     /* interval, -1 for default */
1458         struct delayed_work     dwork;
1459 };
1460 
1461 static const char *disk_events_strs[] = {
1462         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "media_change",
1463         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "eject_request",
1464 };
1465 
1466 static char *disk_uevents[] = {
1467         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "DISK_MEDIA_CHANGE=1",
1468         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "DISK_EJECT_REQUEST=1",
1469 };
1470 
1471 /* list of all disk_events */
1472 static DEFINE_MUTEX(disk_events_mutex);
1473 static LIST_HEAD(disk_events);
1474 
1475 /* disable in-kernel polling by default */
1476 static unsigned long disk_events_dfl_poll_msecs;
1477 
1478 static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
1479 {
1480         struct disk_events *ev = disk->ev;
1481         long intv_msecs = 0;
1482 
1483         /*
1484          * If device-specific poll interval is set, always use it.  If
1485          * the default is being used, poll iff there are events which
1486          * can't be monitored asynchronously.
1487          */
1488         if (ev->poll_msecs >= 0)
1489                 intv_msecs = ev->poll_msecs;
1490         else if (disk->events & ~disk->async_events)
1491                 intv_msecs = disk_events_dfl_poll_msecs;
1492 
1493         return msecs_to_jiffies(intv_msecs);
1494 }
1495 
1496 /**
1497  * disk_block_events - block and flush disk event checking
1498  * @disk: disk to block events for
1499  *
1500  * On return from this function, it is guaranteed that event checking
1501  * isn't in progress and won't happen until unblocked by
1502  * disk_unblock_events().  Events blocking is counted and the actual
1503  * unblocking happens after the matching number of unblocks are done.
1504  *
1505  * Note that this intentionally does not block event checking from
1506  * disk_clear_events().
1507  *
1508  * CONTEXT:
1509  * Might sleep.
1510  */
1511 void disk_block_events(struct gendisk *disk)
1512 {
1513         struct disk_events *ev = disk->ev;
1514         unsigned long flags;
1515         bool cancel;
1516 
1517         if (!ev)
1518                 return;
1519 
1520         /*
1521          * Outer mutex ensures that the first blocker completes canceling
1522          * the event work before further blockers are allowed to finish.
1523          */
1524         mutex_lock(&ev->block_mutex);
1525 
1526         spin_lock_irqsave(&ev->lock, flags);
1527         cancel = !ev->block++;
1528         spin_unlock_irqrestore(&ev->lock, flags);
1529 
1530         if (cancel)
1531                 cancel_delayed_work_sync(&disk->ev->dwork);
1532 
1533         mutex_unlock(&ev->block_mutex);
1534 }
1535 
1536 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
1537 {
1538         struct disk_events *ev = disk->ev;
1539         unsigned long intv;
1540         unsigned long flags;
1541 
1542         spin_lock_irqsave(&ev->lock, flags);
1543 
1544         if (WARN_ON_ONCE(ev->block <= 0))
1545                 goto out_unlock;
1546 
1547         if (--ev->block)
1548                 goto out_unlock;
1549 
1550         intv = disk_events_poll_jiffies(disk);
1551         if (check_now)
1552                 queue_delayed_work(system_freezable_power_efficient_wq,
1553                                 &ev->dwork, 0);
1554         else if (intv)
1555                 queue_delayed_work(system_freezable_power_efficient_wq,
1556                                 &ev->dwork, intv);
1557 out_unlock:
1558         spin_unlock_irqrestore(&ev->lock, flags);
1559 }
1560 
1561 /**
1562  * disk_unblock_events - unblock disk event checking
1563  * @disk: disk to unblock events for
1564  *
1565  * Undo disk_block_events().  When the block count reaches zero, it
1566  * starts events polling if configured.
1567  *
1568  * CONTEXT:
1569  * Don't care.  Safe to call from irq context.
1570  */
1571 void disk_unblock_events(struct gendisk *disk)
1572 {
1573         if (disk->ev)
1574                 __disk_unblock_events(disk, false);
1575 }
1576 
1577 /**
1578  * disk_flush_events - schedule immediate event checking and flushing
1579  * @disk: disk to check and flush events for
1580  * @mask: events to flush
1581  *
1582  * Schedule immediate event checking on @disk if not blocked.  Events in
1583  * @mask are scheduled to be cleared from the driver.  Note that this
1584  * doesn't clear the events from @disk->ev.
1585  *
1586  * CONTEXT:
1587  * If @mask is non-zero must be called with bdev->bd_mutex held.
1588  */
1589 void disk_flush_events(struct gendisk *disk, unsigned int mask)
1590 {
1591         struct disk_events *ev = disk->ev;
1592 
1593         if (!ev)
1594                 return;
1595 
1596         spin_lock_irq(&ev->lock);
1597         ev->clearing |= mask;
1598         if (!ev->block)
1599                 mod_delayed_work(system_freezable_power_efficient_wq,
1600                                 &ev->dwork, 0);
1601         spin_unlock_irq(&ev->lock);
1602 }
1603 
1604 /**
1605  * disk_clear_events - synchronously check, clear and return pending events
1606  * @disk: disk to fetch and clear events from
1607  * @mask: mask of events to be fetched and cleared
1608  *
1609  * Disk events are synchronously checked and pending events in @mask
1610  * are cleared and returned.  This ignores the block count.
1611  *
1612  * CONTEXT:
1613  * Might sleep.
1614  */
1615 unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
1616 {
1617         const struct block_device_operations *bdops = disk->fops;
1618         struct disk_events *ev = disk->ev;
1619         unsigned int pending;
1620         unsigned int clearing = mask;
1621 
1622         if (!ev) {
1623                 /* for drivers still using the old ->media_changed method */
1624                 if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
1625                     bdops->media_changed && bdops->media_changed(disk))
1626                         return DISK_EVENT_MEDIA_CHANGE;
1627                 return 0;
1628         }
1629 
1630         disk_block_events(disk);
1631 
1632         /*
1633          * store the union of mask and ev->clearing on the stack so that the
1634          * race with disk_flush_events does not cause ambiguity (ev->clearing
1635          * can still be modified even if events are blocked).
1636          */
1637         spin_lock_irq(&ev->lock);
1638         clearing |= ev->clearing;
1639         ev->clearing = 0;
1640         spin_unlock_irq(&ev->lock);
1641 
1642         disk_check_events(ev, &clearing);
1643         /*
1644          * if ev->clearing is not 0, the disk_flush_events got called in the
1645          * middle of this function, so we want to run the workfn without delay.
1646          */
1647         __disk_unblock_events(disk, ev->clearing ? true : false);
1648 
1649         /* then, fetch and clear pending events */
1650         spin_lock_irq(&ev->lock);
1651         pending = ev->pending & mask;
1652         ev->pending &= ~mask;
1653         spin_unlock_irq(&ev->lock);
1654         WARN_ON_ONCE(clearing & mask);
1655 
1656         return pending;
1657 }
1658 
1659 /*
1660  * Separate this part out so that a different pointer for clearing_ptr can be
1661  * passed in for disk_clear_events.
1662  */
1663 static void disk_events_workfn(struct work_struct *work)
1664 {
1665         struct delayed_work *dwork = to_delayed_work(work);
1666         struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
1667 
1668         disk_check_events(ev, &ev->clearing);
1669 }
1670 
1671 static void disk_check_events(struct disk_events *ev,
1672                               unsigned int *clearing_ptr)
1673 {
1674         struct gendisk *disk = ev->disk;
1675         char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
1676         unsigned int clearing = *clearing_ptr;
1677         unsigned int events;
1678         unsigned long intv;
1679         int nr_events = 0, i;
1680 
1681         /* check events */
1682         events = disk->fops->check_events(disk, clearing);
1683 
1684         /* accumulate pending events and schedule next poll if necessary */
1685         spin_lock_irq(&ev->lock);
1686 
1687         events &= ~ev->pending;
1688         ev->pending |= events;
1689         *clearing_ptr &= ~clearing;
1690 
1691         intv = disk_events_poll_jiffies(disk);
1692         if (!ev->block && intv)
1693                 queue_delayed_work(system_freezable_power_efficient_wq,
1694                                 &ev->dwork, intv);
1695 
1696         spin_unlock_irq(&ev->lock);
1697 
1698         /*
1699          * Tell userland about new events.  Only the events listed in
1700          * @disk->events are reported.  Unlisted events are processed the
1701          * same internally but never get reported to userland.
1702          */
1703         for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
1704                 if (events & disk->events & (1 << i))
1705                         envp[nr_events++] = disk_uevents[i];
1706 
1707         if (nr_events)
1708                 kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
1709 }
1710 
1711 /*
1712  * A disk events enabled device has the following sysfs nodes under
1713  * its /sys/block/X/ directory.
1714  *
1715  * events               : list of all supported events
1716  * events_async         : list of events which can be detected w/o polling
1717  * events_poll_msecs    : polling interval, 0: disable, -1: system default
1718  */
1719 static ssize_t __disk_events_show(unsigned int events, char *buf)
1720 {
1721         const char *delim = "";
1722         ssize_t pos = 0;
1723         int i;
1724 
1725         for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
1726                 if (events & (1 << i)) {
1727                         pos += sprintf(buf + pos, "%s%s",
1728                                        delim, disk_events_strs[i]);
1729                         delim = " ";
1730                 }
1731         if (pos)
1732                 pos += sprintf(buf + pos, "\n");
1733         return pos;
1734 }
1735 
1736 static ssize_t disk_events_show(struct device *dev,
1737                                 struct device_attribute *attr, char *buf)
1738 {
1739         struct gendisk *disk = dev_to_disk(dev);
1740 
1741         return __disk_events_show(disk->events, buf);
1742 }
1743 
1744 static ssize_t disk_events_async_show(struct device *dev,
1745                                       struct device_attribute *attr, char *buf)
1746 {
1747         struct gendisk *disk = dev_to_disk(dev);
1748 
1749         return __disk_events_show(disk->async_events, buf);
1750 }
1751 
1752 static ssize_t disk_events_poll_msecs_show(struct device *dev,
1753                                            struct device_attribute *attr,
1754                                            char *buf)
1755 {
1756         struct gendisk *disk = dev_to_disk(dev);
1757 
1758         return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
1759 }
1760 
1761 static ssize_t disk_events_poll_msecs_store(struct device *dev,
1762                                             struct device_attribute *attr,
1763                                             const char *buf, size_t count)
1764 {
1765         struct gendisk *disk = dev_to_disk(dev);
1766         long intv;
1767 
1768         if (!count || !sscanf(buf, "%ld", &intv))
1769                 return -EINVAL;
1770 
1771         if (intv < 0 && intv != -1)
1772                 return -EINVAL;
1773 
1774         disk_block_events(disk);
1775         disk->ev->poll_msecs = intv;
1776         __disk_unblock_events(disk, true);
1777 
1778         return count;
1779 }
1780 
1781 static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
1782 static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
1783 static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
1784                          disk_events_poll_msecs_show,
1785                          disk_events_poll_msecs_store);
1786 
1787 static const struct attribute *disk_events_attrs[] = {
1788         &dev_attr_events.attr,
1789         &dev_attr_events_async.attr,
1790         &dev_attr_events_poll_msecs.attr,
1791         NULL,
1792 };
1793 
1794 /*
1795  * The default polling interval can be specified by the kernel
1796  * parameter block.events_dfl_poll_msecs which defaults to 0
1797  * (disable).  This can also be modified runtime by writing to
1798  * /sys/module/block/events_dfl_poll_msecs.
1799  */
1800 static int disk_events_set_dfl_poll_msecs(const char *val,
1801                                           const struct kernel_param *kp)
1802 {
1803         struct disk_events *ev;
1804         int ret;
1805 
1806         ret = param_set_ulong(val, kp);
1807         if (ret < 0)
1808                 return ret;
1809 
1810         mutex_lock(&disk_events_mutex);
1811 
1812         list_for_each_entry(ev, &disk_events, node)
1813                 disk_flush_events(ev->disk, 0);
1814 
1815         mutex_unlock(&disk_events_mutex);
1816 
1817         return 0;
1818 }
1819 
1820 static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
1821         .set    = disk_events_set_dfl_poll_msecs,
1822         .get    = param_get_ulong,
1823 };
1824 
1825 #undef MODULE_PARAM_PREFIX
1826 #define MODULE_PARAM_PREFIX     "block."
1827 
1828 module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
1829                 &disk_events_dfl_poll_msecs, 0644);
1830 
1831 /*
1832  * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
1833  */
1834 static void disk_alloc_events(struct gendisk *disk)
1835 {
1836         struct disk_events *ev;
1837 
1838         if (!disk->fops->check_events)
1839                 return;
1840 
1841         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
1842         if (!ev) {
1843                 pr_warn("%s: failed to initialize events\n", disk->disk_name);
1844                 return;
1845         }
1846 
1847         INIT_LIST_HEAD(&ev->node);
1848         ev->disk = disk;
1849         spin_lock_init(&ev->lock);
1850         mutex_init(&ev->block_mutex);
1851         ev->block = 1;
1852         ev->poll_msecs = -1;
1853         INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
1854 
1855         disk->ev = ev;
1856 }
1857 
1858 static void disk_add_events(struct gendisk *disk)
1859 {
1860         if (!disk->ev)
1861                 return;
1862 
1863         /* FIXME: error handling */
1864         if (sysfs_create_files(&disk_to_dev(disk)->kobj, disk_events_attrs) < 0)
1865                 pr_warn("%s: failed to create sysfs files for events\n",
1866                         disk->disk_name);
1867 
1868         mutex_lock(&disk_events_mutex);
1869         list_add_tail(&disk->ev->node, &disk_events);
1870         mutex_unlock(&disk_events_mutex);
1871 
1872         /*
1873          * Block count is initialized to 1 and the following initial
1874          * unblock kicks it into action.
1875          */
1876         __disk_unblock_events(disk, true);
1877 }
1878 
1879 static void disk_del_events(struct gendisk *disk)
1880 {
1881         if (!disk->ev)
1882                 return;
1883 
1884         disk_block_events(disk);
1885 
1886         mutex_lock(&disk_events_mutex);
1887         list_del_init(&disk->ev->node);
1888         mutex_unlock(&disk_events_mutex);
1889 
1890         sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
1891 }
1892 
1893 static void disk_release_events(struct gendisk *disk)
1894 {
1895         /* the block count should be 1 from disk_del_events() */
1896         WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
1897         kfree(disk->ev);
1898 }
1899 

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