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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 void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int rw)
 49 {
 50         if (q->mq_ops)
 51                 return;
 52 
 53         atomic_inc(&part->in_flight[rw]);
 54         if (part->partno)
 55                 atomic_inc(&part_to_disk(part)->part0.in_flight[rw]);
 56 }
 57 
 58 void part_dec_in_flight(struct request_queue *q, struct hd_struct *part, int rw)
 59 {
 60         if (q->mq_ops)
 61                 return;
 62 
 63         atomic_dec(&part->in_flight[rw]);
 64         if (part->partno)
 65                 atomic_dec(&part_to_disk(part)->part0.in_flight[rw]);
 66 }
 67 
 68 void part_in_flight(struct request_queue *q, struct hd_struct *part,
 69                     unsigned int inflight[2])
 70 {
 71         if (q->mq_ops) {
 72                 blk_mq_in_flight(q, part, inflight);
 73                 return;
 74         }
 75 
 76         inflight[0] = atomic_read(&part->in_flight[0]) +
 77                         atomic_read(&part->in_flight[1]);
 78         if (part->partno) {
 79                 part = &part_to_disk(part)->part0;
 80                 inflight[1] = atomic_read(&part->in_flight[0]) +
 81                                 atomic_read(&part->in_flight[1]);
 82         }
 83 }
 84 
 85 void part_in_flight_rw(struct request_queue *q, struct hd_struct *part,
 86                        unsigned int inflight[2])
 87 {
 88         if (q->mq_ops) {
 89                 blk_mq_in_flight_rw(q, part, inflight);
 90                 return;
 91         }
 92 
 93         inflight[0] = atomic_read(&part->in_flight[0]);
 94         inflight[1] = atomic_read(&part->in_flight[1]);
 95 }
 96 
 97 struct hd_struct *__disk_get_part(struct gendisk *disk, int partno)
 98 {
 99         struct disk_part_tbl *ptbl = rcu_dereference(disk->part_tbl);
100 
101         if (unlikely(partno < 0 || partno >= ptbl->len))
102                 return NULL;
103         return rcu_dereference(ptbl->part[partno]);
104 }
105 
106 /**
107  * disk_get_part - get partition
108  * @disk: disk to look partition from
109  * @partno: partition number
110  *
111  * Look for partition @partno from @disk.  If found, increment
112  * reference count and return it.
113  *
114  * CONTEXT:
115  * Don't care.
116  *
117  * RETURNS:
118  * Pointer to the found partition on success, NULL if not found.
119  */
120 struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
121 {
122         struct hd_struct *part;
123 
124         rcu_read_lock();
125         part = __disk_get_part(disk, partno);
126         if (part)
127                 get_device(part_to_dev(part));
128         rcu_read_unlock();
129 
130         return part;
131 }
132 EXPORT_SYMBOL_GPL(disk_get_part);
133 
134 /**
135  * disk_part_iter_init - initialize partition iterator
136  * @piter: iterator to initialize
137  * @disk: disk to iterate over
138  * @flags: DISK_PITER_* flags
139  *
140  * Initialize @piter so that it iterates over partitions of @disk.
141  *
142  * CONTEXT:
143  * Don't care.
144  */
145 void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
146                           unsigned int flags)
147 {
148         struct disk_part_tbl *ptbl;
149 
150         rcu_read_lock();
151         ptbl = rcu_dereference(disk->part_tbl);
152 
153         piter->disk = disk;
154         piter->part = NULL;
155 
156         if (flags & DISK_PITER_REVERSE)
157                 piter->idx = ptbl->len - 1;
158         else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
159                 piter->idx = 0;
160         else
161                 piter->idx = 1;
162 
163         piter->flags = flags;
164 
165         rcu_read_unlock();
166 }
167 EXPORT_SYMBOL_GPL(disk_part_iter_init);
168 
169 /**
170  * disk_part_iter_next - proceed iterator to the next partition and return it
171  * @piter: iterator of interest
172  *
173  * Proceed @piter to the next partition and return it.
174  *
175  * CONTEXT:
176  * Don't care.
177  */
178 struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
179 {
180         struct disk_part_tbl *ptbl;
181         int inc, end;
182 
183         /* put the last partition */
184         disk_put_part(piter->part);
185         piter->part = NULL;
186 
187         /* get part_tbl */
188         rcu_read_lock();
189         ptbl = rcu_dereference(piter->disk->part_tbl);
190 
191         /* determine iteration parameters */
192         if (piter->flags & DISK_PITER_REVERSE) {
193                 inc = -1;
194                 if (piter->flags & (DISK_PITER_INCL_PART0 |
195                                     DISK_PITER_INCL_EMPTY_PART0))
196                         end = -1;
197                 else
198                         end = 0;
199         } else {
200                 inc = 1;
201                 end = ptbl->len;
202         }
203 
204         /* iterate to the next partition */
205         for (; piter->idx != end; piter->idx += inc) {
206                 struct hd_struct *part;
207 
208                 part = rcu_dereference(ptbl->part[piter->idx]);
209                 if (!part)
210                         continue;
211                 if (!part_nr_sects_read(part) &&
212                     !(piter->flags & DISK_PITER_INCL_EMPTY) &&
213                     !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
214                       piter->idx == 0))
215                         continue;
216 
217                 get_device(part_to_dev(part));
218                 piter->part = part;
219                 piter->idx += inc;
220                 break;
221         }
222 
223         rcu_read_unlock();
224 
225         return piter->part;
226 }
227 EXPORT_SYMBOL_GPL(disk_part_iter_next);
228 
229 /**
230  * disk_part_iter_exit - finish up partition iteration
231  * @piter: iter of interest
232  *
233  * Called when iteration is over.  Cleans up @piter.
234  *
235  * CONTEXT:
236  * Don't care.
237  */
238 void disk_part_iter_exit(struct disk_part_iter *piter)
239 {
240         disk_put_part(piter->part);
241         piter->part = NULL;
242 }
243 EXPORT_SYMBOL_GPL(disk_part_iter_exit);
244 
245 static inline int sector_in_part(struct hd_struct *part, sector_t sector)
246 {
247         return part->start_sect <= sector &&
248                 sector < part->start_sect + part_nr_sects_read(part);
249 }
250 
251 /**
252  * disk_map_sector_rcu - map sector to partition
253  * @disk: gendisk of interest
254  * @sector: sector to map
255  *
256  * Find out which partition @sector maps to on @disk.  This is
257  * primarily used for stats accounting.
258  *
259  * CONTEXT:
260  * RCU read locked.  The returned partition pointer is valid only
261  * while preemption is disabled.
262  *
263  * RETURNS:
264  * Found partition on success, part0 is returned if no partition matches
265  */
266 struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
267 {
268         struct disk_part_tbl *ptbl;
269         struct hd_struct *part;
270         int i;
271 
272         ptbl = rcu_dereference(disk->part_tbl);
273 
274         part = rcu_dereference(ptbl->last_lookup);
275         if (part && sector_in_part(part, sector))
276                 return part;
277 
278         for (i = 1; i < ptbl->len; i++) {
279                 part = rcu_dereference(ptbl->part[i]);
280 
281                 if (part && sector_in_part(part, sector)) {
282                         rcu_assign_pointer(ptbl->last_lookup, part);
283                         return part;
284                 }
285         }
286         return &disk->part0;
287 }
288 EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
289 
290 /*
291  * Can be deleted altogether. Later.
292  *
293  */
294 #define BLKDEV_MAJOR_HASH_SIZE 255
295 static struct blk_major_name {
296         struct blk_major_name *next;
297         int major;
298         char name[16];
299 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
300 
301 /* index in the above - for now: assume no multimajor ranges */
302 static inline int major_to_index(unsigned major)
303 {
304         return major % BLKDEV_MAJOR_HASH_SIZE;
305 }
306 
307 #ifdef CONFIG_PROC_FS
308 void blkdev_show(struct seq_file *seqf, off_t offset)
309 {
310         struct blk_major_name *dp;
311 
312         mutex_lock(&block_class_lock);
313         for (dp = major_names[major_to_index(offset)]; dp; dp = dp->next)
314                 if (dp->major == offset)
315                         seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
316         mutex_unlock(&block_class_lock);
317 }
318 #endif /* CONFIG_PROC_FS */
319 
320 /**
321  * register_blkdev - register a new block device
322  *
323  * @major: the requested major device number [1..BLKDEV_MAJOR_MAX-1]. If
324  *         @major = 0, try to allocate any unused major number.
325  * @name: the name of the new block device as a zero terminated string
326  *
327  * The @name must be unique within the system.
328  *
329  * The return value depends on the @major input parameter:
330  *
331  *  - if a major device number was requested in range [1..BLKDEV_MAJOR_MAX-1]
332  *    then the function returns zero on success, or a negative error code
333  *  - if any unused major number was requested with @major = 0 parameter
334  *    then the return value is the allocated major number in range
335  *    [1..BLKDEV_MAJOR_MAX-1] or a negative error code otherwise
336  *
337  * See Documentation/admin-guide/devices.txt for the list of allocated
338  * major numbers.
339  */
340 int register_blkdev(unsigned int major, const char *name)
341 {
342         struct blk_major_name **n, *p;
343         int index, ret = 0;
344 
345         mutex_lock(&block_class_lock);
346 
347         /* temporary */
348         if (major == 0) {
349                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
350                         if (major_names[index] == NULL)
351                                 break;
352                 }
353 
354                 if (index == 0) {
355                         printk("register_blkdev: failed to get major for %s\n",
356                                name);
357                         ret = -EBUSY;
358                         goto out;
359                 }
360                 major = index;
361                 ret = major;
362         }
363 
364         if (major >= BLKDEV_MAJOR_MAX) {
365                 pr_err("register_blkdev: major requested (%u) is greater than the maximum (%u) for %s\n",
366                        major, BLKDEV_MAJOR_MAX-1, name);
367 
368                 ret = -EINVAL;
369                 goto out;
370         }
371 
372         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
373         if (p == NULL) {
374                 ret = -ENOMEM;
375                 goto out;
376         }
377 
378         p->major = major;
379         strlcpy(p->name, name, sizeof(p->name));
380         p->next = NULL;
381         index = major_to_index(major);
382 
383         for (n = &major_names[index]; *n; n = &(*n)->next) {
384                 if ((*n)->major == major)
385                         break;
386         }
387         if (!*n)
388                 *n = p;
389         else
390                 ret = -EBUSY;
391 
392         if (ret < 0) {
393                 printk("register_blkdev: cannot get major %u for %s\n",
394                        major, name);
395                 kfree(p);
396         }
397 out:
398         mutex_unlock(&block_class_lock);
399         return ret;
400 }
401 
402 EXPORT_SYMBOL(register_blkdev);
403 
404 void unregister_blkdev(unsigned int major, const char *name)
405 {
406         struct blk_major_name **n;
407         struct blk_major_name *p = NULL;
408         int index = major_to_index(major);
409 
410         mutex_lock(&block_class_lock);
411         for (n = &major_names[index]; *n; n = &(*n)->next)
412                 if ((*n)->major == major)
413                         break;
414         if (!*n || strcmp((*n)->name, name)) {
415                 WARN_ON(1);
416         } else {
417                 p = *n;
418                 *n = p->next;
419         }
420         mutex_unlock(&block_class_lock);
421         kfree(p);
422 }
423 
424 EXPORT_SYMBOL(unregister_blkdev);
425 
426 static struct kobj_map *bdev_map;
427 
428 /**
429  * blk_mangle_minor - scatter minor numbers apart
430  * @minor: minor number to mangle
431  *
432  * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
433  * is enabled.  Mangling twice gives the original value.
434  *
435  * RETURNS:
436  * Mangled value.
437  *
438  * CONTEXT:
439  * Don't care.
440  */
441 static int blk_mangle_minor(int minor)
442 {
443 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
444         int i;
445 
446         for (i = 0; i < MINORBITS / 2; i++) {
447                 int low = minor & (1 << i);
448                 int high = minor & (1 << (MINORBITS - 1 - i));
449                 int distance = MINORBITS - 1 - 2 * i;
450 
451                 minor ^= low | high;    /* clear both bits */
452                 low <<= distance;       /* swap the positions */
453                 high >>= distance;
454                 minor |= low | high;    /* and set */
455         }
456 #endif
457         return minor;
458 }
459 
460 /**
461  * blk_alloc_devt - allocate a dev_t for a partition
462  * @part: partition to allocate dev_t for
463  * @devt: out parameter for resulting dev_t
464  *
465  * Allocate a dev_t for block device.
466  *
467  * RETURNS:
468  * 0 on success, allocated dev_t is returned in *@devt.  -errno on
469  * failure.
470  *
471  * CONTEXT:
472  * Might sleep.
473  */
474 int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
475 {
476         struct gendisk *disk = part_to_disk(part);
477         int idx;
478 
479         /* in consecutive minor range? */
480         if (part->partno < disk->minors) {
481                 *devt = MKDEV(disk->major, disk->first_minor + part->partno);
482                 return 0;
483         }
484 
485         /* allocate ext devt */
486         idr_preload(GFP_KERNEL);
487 
488         spin_lock_bh(&ext_devt_lock);
489         idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);
490         spin_unlock_bh(&ext_devt_lock);
491 
492         idr_preload_end();
493         if (idx < 0)
494                 return idx == -ENOSPC ? -EBUSY : idx;
495 
496         *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
497         return 0;
498 }
499 
500 /**
501  * blk_free_devt - free a dev_t
502  * @devt: dev_t to free
503  *
504  * Free @devt which was allocated using blk_alloc_devt().
505  *
506  * CONTEXT:
507  * Might sleep.
508  */
509 void blk_free_devt(dev_t devt)
510 {
511         if (devt == MKDEV(0, 0))
512                 return;
513 
514         if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
515                 spin_lock_bh(&ext_devt_lock);
516                 idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
517                 spin_unlock_bh(&ext_devt_lock);
518         }
519 }
520 
521 static char *bdevt_str(dev_t devt, char *buf)
522 {
523         if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
524                 char tbuf[BDEVT_SIZE];
525                 snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
526                 snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
527         } else
528                 snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
529 
530         return buf;
531 }
532 
533 /*
534  * Register device numbers dev..(dev+range-1)
535  * range must be nonzero
536  * The hash chain is sorted on range, so that subranges can override.
537  */
538 void blk_register_region(dev_t devt, unsigned long range, struct module *module,
539                          struct kobject *(*probe)(dev_t, int *, void *),
540                          int (*lock)(dev_t, void *), void *data)
541 {
542         kobj_map(bdev_map, devt, range, module, probe, lock, data);
543 }
544 
545 EXPORT_SYMBOL(blk_register_region);
546 
547 void blk_unregister_region(dev_t devt, unsigned long range)
548 {
549         kobj_unmap(bdev_map, devt, range);
550 }
551 
552 EXPORT_SYMBOL(blk_unregister_region);
553 
554 static struct kobject *exact_match(dev_t devt, int *partno, void *data)
555 {
556         struct gendisk *p = data;
557 
558         return &disk_to_dev(p)->kobj;
559 }
560 
561 static int exact_lock(dev_t devt, void *data)
562 {
563         struct gendisk *p = data;
564 
565         if (!get_disk_and_module(p))
566                 return -1;
567         return 0;
568 }
569 
570 static void register_disk(struct device *parent, struct gendisk *disk)
571 {
572         struct device *ddev = disk_to_dev(disk);
573         struct block_device *bdev;
574         struct disk_part_iter piter;
575         struct hd_struct *part;
576         int err;
577 
578         ddev->parent = parent;
579 
580         dev_set_name(ddev, "%s", disk->disk_name);
581 
582         /* delay uevents, until we scanned partition table */
583         dev_set_uevent_suppress(ddev, 1);
584 
585         if (device_add(ddev))
586                 return;
587         if (!sysfs_deprecated) {
588                 err = sysfs_create_link(block_depr, &ddev->kobj,
589                                         kobject_name(&ddev->kobj));
590                 if (err) {
591                         device_del(ddev);
592                         return;
593                 }
594         }
595 
596         /*
597          * avoid probable deadlock caused by allocating memory with
598          * GFP_KERNEL in runtime_resume callback of its all ancestor
599          * devices
600          */
601         pm_runtime_set_memalloc_noio(ddev, true);
602 
603         disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
604         disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
605 
606         if (disk->flags & GENHD_FL_HIDDEN) {
607                 dev_set_uevent_suppress(ddev, 0);
608                 return;
609         }
610 
611         /* No minors to use for partitions */
612         if (!disk_part_scan_enabled(disk))
613                 goto exit;
614 
615         /* No such device (e.g., media were just removed) */
616         if (!get_capacity(disk))
617                 goto exit;
618 
619         bdev = bdget_disk(disk, 0);
620         if (!bdev)
621                 goto exit;
622 
623         bdev->bd_invalidated = 1;
624         err = blkdev_get(bdev, FMODE_READ, NULL);
625         if (err < 0)
626                 goto exit;
627         blkdev_put(bdev, FMODE_READ);
628 
629 exit:
630         /* announce disk after possible partitions are created */
631         dev_set_uevent_suppress(ddev, 0);
632         kobject_uevent(&ddev->kobj, KOBJ_ADD);
633 
634         /* announce possible partitions */
635         disk_part_iter_init(&piter, disk, 0);
636         while ((part = disk_part_iter_next(&piter)))
637                 kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
638         disk_part_iter_exit(&piter);
639 
640         err = sysfs_create_link(&ddev->kobj,
641                                 &disk->queue->backing_dev_info->dev->kobj,
642                                 "bdi");
643         WARN_ON(err);
644 }
645 
646 /**
647  * __device_add_disk - add disk information to kernel list
648  * @parent: parent device for the disk
649  * @disk: per-device partitioning information
650  * @register_queue: register the queue if set to true
651  *
652  * This function registers the partitioning information in @disk
653  * with the kernel.
654  *
655  * FIXME: error handling
656  */
657 static void __device_add_disk(struct device *parent, struct gendisk *disk,
658                               bool register_queue)
659 {
660         dev_t devt;
661         int retval;
662 
663         /* minors == 0 indicates to use ext devt from part0 and should
664          * be accompanied with EXT_DEVT flag.  Make sure all
665          * parameters make sense.
666          */
667         WARN_ON(disk->minors && !(disk->major || disk->first_minor));
668         WARN_ON(!disk->minors &&
669                 !(disk->flags & (GENHD_FL_EXT_DEVT | GENHD_FL_HIDDEN)));
670 
671         disk->flags |= GENHD_FL_UP;
672 
673         retval = blk_alloc_devt(&disk->part0, &devt);
674         if (retval) {
675                 WARN_ON(1);
676                 return;
677         }
678         disk->major = MAJOR(devt);
679         disk->first_minor = MINOR(devt);
680 
681         disk_alloc_events(disk);
682 
683         if (disk->flags & GENHD_FL_HIDDEN) {
684                 /*
685                  * Don't let hidden disks show up in /proc/partitions,
686                  * and don't bother scanning for partitions either.
687                  */
688                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
689                 disk->flags |= GENHD_FL_NO_PART_SCAN;
690         } else {
691                 int ret;
692 
693                 /* Register BDI before referencing it from bdev */
694                 disk_to_dev(disk)->devt = devt;
695                 ret = bdi_register_owner(disk->queue->backing_dev_info,
696                                                 disk_to_dev(disk));
697                 WARN_ON(ret);
698                 blk_register_region(disk_devt(disk), disk->minors, NULL,
699                                     exact_match, exact_lock, disk);
700         }
701         register_disk(parent, disk);
702         if (register_queue)
703                 blk_register_queue(disk);
704 
705         /*
706          * Take an extra ref on queue which will be put on disk_release()
707          * so that it sticks around as long as @disk is there.
708          */
709         WARN_ON_ONCE(!blk_get_queue(disk->queue));
710 
711         disk_add_events(disk);
712         blk_integrity_add(disk);
713 }
714 
715 void device_add_disk(struct device *parent, struct gendisk *disk)
716 {
717         __device_add_disk(parent, disk, true);
718 }
719 EXPORT_SYMBOL(device_add_disk);
720 
721 void device_add_disk_no_queue_reg(struct device *parent, struct gendisk *disk)
722 {
723         __device_add_disk(parent, disk, false);
724 }
725 EXPORT_SYMBOL(device_add_disk_no_queue_reg);
726 
727 void del_gendisk(struct gendisk *disk)
728 {
729         struct disk_part_iter piter;
730         struct hd_struct *part;
731 
732         blk_integrity_del(disk);
733         disk_del_events(disk);
734 
735         /*
736          * Block lookups of the disk until all bdevs are unhashed and the
737          * disk is marked as dead (GENHD_FL_UP cleared).
738          */
739         down_write(&disk->lookup_sem);
740         /* invalidate stuff */
741         disk_part_iter_init(&piter, disk,
742                              DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
743         while ((part = disk_part_iter_next(&piter))) {
744                 invalidate_partition(disk, part->partno);
745                 bdev_unhash_inode(part_devt(part));
746                 delete_partition(disk, part->partno);
747         }
748         disk_part_iter_exit(&piter);
749 
750         invalidate_partition(disk, 0);
751         bdev_unhash_inode(disk_devt(disk));
752         set_capacity(disk, 0);
753         disk->flags &= ~GENHD_FL_UP;
754         up_write(&disk->lookup_sem);
755 
756         if (!(disk->flags & GENHD_FL_HIDDEN))
757                 sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
758         if (disk->queue) {
759                 /*
760                  * Unregister bdi before releasing device numbers (as they can
761                  * get reused and we'd get clashes in sysfs).
762                  */
763                 if (!(disk->flags & GENHD_FL_HIDDEN))
764                         bdi_unregister(disk->queue->backing_dev_info);
765                 blk_unregister_queue(disk);
766         } else {
767                 WARN_ON(1);
768         }
769 
770         if (!(disk->flags & GENHD_FL_HIDDEN))
771                 blk_unregister_region(disk_devt(disk), disk->minors);
772 
773         kobject_put(disk->part0.holder_dir);
774         kobject_put(disk->slave_dir);
775 
776         part_stat_set_all(&disk->part0, 0);
777         disk->part0.stamp = 0;
778         if (!sysfs_deprecated)
779                 sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
780         pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
781         device_del(disk_to_dev(disk));
782 }
783 EXPORT_SYMBOL(del_gendisk);
784 
785 /* sysfs access to bad-blocks list. */
786 static ssize_t disk_badblocks_show(struct device *dev,
787                                         struct device_attribute *attr,
788                                         char *page)
789 {
790         struct gendisk *disk = dev_to_disk(dev);
791 
792         if (!disk->bb)
793                 return sprintf(page, "\n");
794 
795         return badblocks_show(disk->bb, page, 0);
796 }
797 
798 static ssize_t disk_badblocks_store(struct device *dev,
799                                         struct device_attribute *attr,
800                                         const char *page, size_t len)
801 {
802         struct gendisk *disk = dev_to_disk(dev);
803 
804         if (!disk->bb)
805                 return -ENXIO;
806 
807         return badblocks_store(disk->bb, page, len, 0);
808 }
809 
810 /**
811  * get_gendisk - get partitioning information for a given device
812  * @devt: device to get partitioning information for
813  * @partno: returned partition index
814  *
815  * This function gets the structure containing partitioning
816  * information for the given device @devt.
817  */
818 struct gendisk *get_gendisk(dev_t devt, int *partno)
819 {
820         struct gendisk *disk = NULL;
821 
822         if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
823                 struct kobject *kobj;
824 
825                 kobj = kobj_lookup(bdev_map, devt, partno);
826                 if (kobj)
827                         disk = dev_to_disk(kobj_to_dev(kobj));
828         } else {
829                 struct hd_struct *part;
830 
831                 spin_lock_bh(&ext_devt_lock);
832                 part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
833                 if (part && get_disk_and_module(part_to_disk(part))) {
834                         *partno = part->partno;
835                         disk = part_to_disk(part);
836                 }
837                 spin_unlock_bh(&ext_devt_lock);
838         }
839 
840         if (!disk)
841                 return NULL;
842 
843         /*
844          * Synchronize with del_gendisk() to not return disk that is being
845          * destroyed.
846          */
847         down_read(&disk->lookup_sem);
848         if (unlikely((disk->flags & GENHD_FL_HIDDEN) ||
849                      !(disk->flags & GENHD_FL_UP))) {
850                 up_read(&disk->lookup_sem);
851                 put_disk_and_module(disk);
852                 disk = NULL;
853         } else {
854                 up_read(&disk->lookup_sem);
855         }
856         return disk;
857 }
858 EXPORT_SYMBOL(get_gendisk);
859 
860 /**
861  * bdget_disk - do bdget() by gendisk and partition number
862  * @disk: gendisk of interest
863  * @partno: partition number
864  *
865  * Find partition @partno from @disk, do bdget() on it.
866  *
867  * CONTEXT:
868  * Don't care.
869  *
870  * RETURNS:
871  * Resulting block_device on success, NULL on failure.
872  */
873 struct block_device *bdget_disk(struct gendisk *disk, int partno)
874 {
875         struct hd_struct *part;
876         struct block_device *bdev = NULL;
877 
878         part = disk_get_part(disk, partno);
879         if (part)
880                 bdev = bdget(part_devt(part));
881         disk_put_part(part);
882 
883         return bdev;
884 }
885 EXPORT_SYMBOL(bdget_disk);
886 
887 /*
888  * print a full list of all partitions - intended for places where the root
889  * filesystem can't be mounted and thus to give the victim some idea of what
890  * went wrong
891  */
892 void __init printk_all_partitions(void)
893 {
894         struct class_dev_iter iter;
895         struct device *dev;
896 
897         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
898         while ((dev = class_dev_iter_next(&iter))) {
899                 struct gendisk *disk = dev_to_disk(dev);
900                 struct disk_part_iter piter;
901                 struct hd_struct *part;
902                 char name_buf[BDEVNAME_SIZE];
903                 char devt_buf[BDEVT_SIZE];
904 
905                 /*
906                  * Don't show empty devices or things that have been
907                  * suppressed
908                  */
909                 if (get_capacity(disk) == 0 ||
910                     (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
911                         continue;
912 
913                 /*
914                  * Note, unlike /proc/partitions, I am showing the
915                  * numbers in hex - the same format as the root=
916                  * option takes.
917                  */
918                 disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
919                 while ((part = disk_part_iter_next(&piter))) {
920                         bool is_part0 = part == &disk->part0;
921 
922                         printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
923                                bdevt_str(part_devt(part), devt_buf),
924                                (unsigned long long)part_nr_sects_read(part) >> 1
925                                , disk_name(disk, part->partno, name_buf),
926                                part->info ? part->info->uuid : "");
927                         if (is_part0) {
928                                 if (dev->parent && dev->parent->driver)
929                                         printk(" driver: %s\n",
930                                               dev->parent->driver->name);
931                                 else
932                                         printk(" (driver?)\n");
933                         } else
934                                 printk("\n");
935                 }
936                 disk_part_iter_exit(&piter);
937         }
938         class_dev_iter_exit(&iter);
939 }
940 
941 #ifdef CONFIG_PROC_FS
942 /* iterator */
943 static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
944 {
945         loff_t skip = *pos;
946         struct class_dev_iter *iter;
947         struct device *dev;
948 
949         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
950         if (!iter)
951                 return ERR_PTR(-ENOMEM);
952 
953         seqf->private = iter;
954         class_dev_iter_init(iter, &block_class, NULL, &disk_type);
955         do {
956                 dev = class_dev_iter_next(iter);
957                 if (!dev)
958                         return NULL;
959         } while (skip--);
960 
961         return dev_to_disk(dev);
962 }
963 
964 static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
965 {
966         struct device *dev;
967 
968         (*pos)++;
969         dev = class_dev_iter_next(seqf->private);
970         if (dev)
971                 return dev_to_disk(dev);
972 
973         return NULL;
974 }
975 
976 static void disk_seqf_stop(struct seq_file *seqf, void *v)
977 {
978         struct class_dev_iter *iter = seqf->private;
979 
980         /* stop is called even after start failed :-( */
981         if (iter) {
982                 class_dev_iter_exit(iter);
983                 kfree(iter);
984                 seqf->private = NULL;
985         }
986 }
987 
988 static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
989 {
990         void *p;
991 
992         p = disk_seqf_start(seqf, pos);
993         if (!IS_ERR_OR_NULL(p) && !*pos)
994                 seq_puts(seqf, "major minor  #blocks  name\n\n");
995         return p;
996 }
997 
998 static int show_partition(struct seq_file *seqf, void *v)
999 {
1000         struct gendisk *sgp = v;
1001         struct disk_part_iter piter;
1002         struct hd_struct *part;
1003         char buf[BDEVNAME_SIZE];
1004 
1005         /* Don't show non-partitionable removeable devices or empty devices */
1006         if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
1007                                    (sgp->flags & GENHD_FL_REMOVABLE)))
1008                 return 0;
1009         if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
1010                 return 0;
1011 
1012         /* show the full disk and all non-0 size partitions of it */
1013         disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
1014         while ((part = disk_part_iter_next(&piter)))
1015                 seq_printf(seqf, "%4d  %7d %10llu %s\n",
1016                            MAJOR(part_devt(part)), MINOR(part_devt(part)),
1017                            (unsigned long long)part_nr_sects_read(part) >> 1,
1018                            disk_name(sgp, part->partno, buf));
1019         disk_part_iter_exit(&piter);
1020 
1021         return 0;
1022 }
1023 
1024 static const struct seq_operations partitions_op = {
1025         .start  = show_partition_start,
1026         .next   = disk_seqf_next,
1027         .stop   = disk_seqf_stop,
1028         .show   = show_partition
1029 };
1030 
1031 static int partitions_open(struct inode *inode, struct file *file)
1032 {
1033         return seq_open(file, &partitions_op);
1034 }
1035 
1036 static const struct file_operations proc_partitions_operations = {
1037         .open           = partitions_open,
1038         .read           = seq_read,
1039         .llseek         = seq_lseek,
1040         .release        = seq_release,
1041 };
1042 #endif
1043 
1044 
1045 static struct kobject *base_probe(dev_t devt, int *partno, void *data)
1046 {
1047         if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
1048                 /* Make old-style 2.4 aliases work */
1049                 request_module("block-major-%d", MAJOR(devt));
1050         return NULL;
1051 }
1052 
1053 static int __init genhd_device_init(void)
1054 {
1055         int error;
1056 
1057         block_class.dev_kobj = sysfs_dev_block_kobj;
1058         error = class_register(&block_class);
1059         if (unlikely(error))
1060                 return error;
1061         bdev_map = kobj_map_init(base_probe, &block_class_lock);
1062         blk_dev_init();
1063 
1064         register_blkdev(BLOCK_EXT_MAJOR, "blkext");
1065 
1066         /* create top-level block dir */
1067         if (!sysfs_deprecated)
1068                 block_depr = kobject_create_and_add("block", NULL);
1069         return 0;
1070 }
1071 
1072 subsys_initcall(genhd_device_init);
1073 
1074 static ssize_t disk_range_show(struct device *dev,
1075                                struct device_attribute *attr, char *buf)
1076 {
1077         struct gendisk *disk = dev_to_disk(dev);
1078 
1079         return sprintf(buf, "%d\n", disk->minors);
1080 }
1081 
1082 static ssize_t disk_ext_range_show(struct device *dev,
1083                                    struct device_attribute *attr, char *buf)
1084 {
1085         struct gendisk *disk = dev_to_disk(dev);
1086 
1087         return sprintf(buf, "%d\n", disk_max_parts(disk));
1088 }
1089 
1090 static ssize_t disk_removable_show(struct device *dev,
1091                                    struct device_attribute *attr, char *buf)
1092 {
1093         struct gendisk *disk = dev_to_disk(dev);
1094 
1095         return sprintf(buf, "%d\n",
1096                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
1097 }
1098 
1099 static ssize_t disk_hidden_show(struct device *dev,
1100                                    struct device_attribute *attr, char *buf)
1101 {
1102         struct gendisk *disk = dev_to_disk(dev);
1103 
1104         return sprintf(buf, "%d\n",
1105                        (disk->flags & GENHD_FL_HIDDEN ? 1 : 0));
1106 }
1107 
1108 static ssize_t disk_ro_show(struct device *dev,
1109                                    struct device_attribute *attr, char *buf)
1110 {
1111         struct gendisk *disk = dev_to_disk(dev);
1112 
1113         return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
1114 }
1115 
1116 static ssize_t disk_capability_show(struct device *dev,
1117                                     struct device_attribute *attr, char *buf)
1118 {
1119         struct gendisk *disk = dev_to_disk(dev);
1120 
1121         return sprintf(buf, "%x\n", disk->flags);
1122 }
1123 
1124 static ssize_t disk_alignment_offset_show(struct device *dev,
1125                                           struct device_attribute *attr,
1126                                           char *buf)
1127 {
1128         struct gendisk *disk = dev_to_disk(dev);
1129 
1130         return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
1131 }
1132 
1133 static ssize_t disk_discard_alignment_show(struct device *dev,
1134                                            struct device_attribute *attr,
1135                                            char *buf)
1136 {
1137         struct gendisk *disk = dev_to_disk(dev);
1138 
1139         return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));
1140 }
1141 
1142 static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
1143 static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
1144 static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
1145 static DEVICE_ATTR(hidden, S_IRUGO, disk_hidden_show, NULL);
1146 static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
1147 static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
1148 static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
1149 static DEVICE_ATTR(discard_alignment, S_IRUGO, disk_discard_alignment_show,
1150                    NULL);
1151 static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
1152 static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
1153 static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
1154 static DEVICE_ATTR(badblocks, S_IRUGO | S_IWUSR, disk_badblocks_show,
1155                 disk_badblocks_store);
1156 #ifdef CONFIG_FAIL_MAKE_REQUEST
1157 static struct device_attribute dev_attr_fail =
1158         __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
1159 #endif
1160 #ifdef CONFIG_FAIL_IO_TIMEOUT
1161 static struct device_attribute dev_attr_fail_timeout =
1162         __ATTR(io-timeout-fail,  S_IRUGO|S_IWUSR, part_timeout_show,
1163                 part_timeout_store);
1164 #endif
1165 
1166 static struct attribute *disk_attrs[] = {
1167         &dev_attr_range.attr,
1168         &dev_attr_ext_range.attr,
1169         &dev_attr_removable.attr,
1170         &dev_attr_hidden.attr,
1171         &dev_attr_ro.attr,
1172         &dev_attr_size.attr,
1173         &dev_attr_alignment_offset.attr,
1174         &dev_attr_discard_alignment.attr,
1175         &dev_attr_capability.attr,
1176         &dev_attr_stat.attr,
1177         &dev_attr_inflight.attr,
1178         &dev_attr_badblocks.attr,
1179 #ifdef CONFIG_FAIL_MAKE_REQUEST
1180         &dev_attr_fail.attr,
1181 #endif
1182 #ifdef CONFIG_FAIL_IO_TIMEOUT
1183         &dev_attr_fail_timeout.attr,
1184 #endif
1185         NULL
1186 };
1187 
1188 static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)
1189 {
1190         struct device *dev = container_of(kobj, typeof(*dev), kobj);
1191         struct gendisk *disk = dev_to_disk(dev);
1192 
1193         if (a == &dev_attr_badblocks.attr && !disk->bb)
1194                 return 0;
1195         return a->mode;
1196 }
1197 
1198 static struct attribute_group disk_attr_group = {
1199         .attrs = disk_attrs,
1200         .is_visible = disk_visible,
1201 };
1202 
1203 static const struct attribute_group *disk_attr_groups[] = {
1204         &disk_attr_group,
1205         NULL
1206 };
1207 
1208 /**
1209  * disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
1210  * @disk: disk to replace part_tbl for
1211  * @new_ptbl: new part_tbl to install
1212  *
1213  * Replace disk->part_tbl with @new_ptbl in RCU-safe way.  The
1214  * original ptbl is freed using RCU callback.
1215  *
1216  * LOCKING:
1217  * Matching bd_mutex locked or the caller is the only user of @disk.
1218  */
1219 static void disk_replace_part_tbl(struct gendisk *disk,
1220                                   struct disk_part_tbl *new_ptbl)
1221 {
1222         struct disk_part_tbl *old_ptbl =
1223                 rcu_dereference_protected(disk->part_tbl, 1);
1224 
1225         rcu_assign_pointer(disk->part_tbl, new_ptbl);
1226 
1227         if (old_ptbl) {
1228                 rcu_assign_pointer(old_ptbl->last_lookup, NULL);
1229                 kfree_rcu(old_ptbl, rcu_head);
1230         }
1231 }
1232 
1233 /**
1234  * disk_expand_part_tbl - expand disk->part_tbl
1235  * @disk: disk to expand part_tbl for
1236  * @partno: expand such that this partno can fit in
1237  *
1238  * Expand disk->part_tbl such that @partno can fit in.  disk->part_tbl
1239  * uses RCU to allow unlocked dereferencing for stats and other stuff.
1240  *
1241  * LOCKING:
1242  * Matching bd_mutex locked or the caller is the only user of @disk.
1243  * Might sleep.
1244  *
1245  * RETURNS:
1246  * 0 on success, -errno on failure.
1247  */
1248 int disk_expand_part_tbl(struct gendisk *disk, int partno)
1249 {
1250         struct disk_part_tbl *old_ptbl =
1251                 rcu_dereference_protected(disk->part_tbl, 1);
1252         struct disk_part_tbl *new_ptbl;
1253         int len = old_ptbl ? old_ptbl->len : 0;
1254         int i, target;
1255         size_t size;
1256 
1257         /*
1258          * check for int overflow, since we can get here from blkpg_ioctl()
1259          * with a user passed 'partno'.
1260          */
1261         target = partno + 1;
1262         if (target < 0)
1263                 return -EINVAL;
1264 
1265         /* disk_max_parts() is zero during initialization, ignore if so */
1266         if (disk_max_parts(disk) && target > disk_max_parts(disk))
1267                 return -EINVAL;
1268 
1269         if (target <= len)
1270                 return 0;
1271 
1272         size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
1273         new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
1274         if (!new_ptbl)
1275                 return -ENOMEM;
1276 
1277         new_ptbl->len = target;
1278 
1279         for (i = 0; i < len; i++)
1280                 rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
1281 
1282         disk_replace_part_tbl(disk, new_ptbl);
1283         return 0;
1284 }
1285 
1286 static void disk_release(struct device *dev)
1287 {
1288         struct gendisk *disk = dev_to_disk(dev);
1289 
1290         blk_free_devt(dev->devt);
1291         disk_release_events(disk);
1292         kfree(disk->random);
1293         disk_replace_part_tbl(disk, NULL);
1294         hd_free_part(&disk->part0);
1295         if (disk->queue)
1296                 blk_put_queue(disk->queue);
1297         kfree(disk);
1298 }
1299 struct class block_class = {
1300         .name           = "block",
1301 };
1302 
1303 static char *block_devnode(struct device *dev, umode_t *mode,
1304                            kuid_t *uid, kgid_t *gid)
1305 {
1306         struct gendisk *disk = dev_to_disk(dev);
1307 
1308         if (disk->devnode)
1309                 return disk->devnode(disk, mode);
1310         return NULL;
1311 }
1312 
1313 static const struct device_type disk_type = {
1314         .name           = "disk",
1315         .groups         = disk_attr_groups,
1316         .release        = disk_release,
1317         .devnode        = block_devnode,
1318 };
1319 
1320 #ifdef CONFIG_PROC_FS
1321 /*
1322  * aggregate disk stat collector.  Uses the same stats that the sysfs
1323  * entries do, above, but makes them available through one seq_file.
1324  *
1325  * The output looks suspiciously like /proc/partitions with a bunch of
1326  * extra fields.
1327  */
1328 static int diskstats_show(struct seq_file *seqf, void *v)
1329 {
1330         struct gendisk *gp = v;
1331         struct disk_part_iter piter;
1332         struct hd_struct *hd;
1333         char buf[BDEVNAME_SIZE];
1334         unsigned int inflight[2];
1335         int cpu;
1336 
1337         /*
1338         if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
1339                 seq_puts(seqf,  "major minor name"
1340                                 "     rio rmerge rsect ruse wio wmerge "
1341                                 "wsect wuse running use aveq"
1342                                 "\n\n");
1343         */
1344 
1345         disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
1346         while ((hd = disk_part_iter_next(&piter))) {
1347                 cpu = part_stat_lock();
1348                 part_round_stats(gp->queue, cpu, hd);
1349                 part_stat_unlock();
1350                 part_in_flight(gp->queue, hd, inflight);
1351                 seq_printf(seqf, "%4d %7d %s %lu %lu %lu "
1352                            "%u %lu %lu %lu %u %u %u %u\n",
1353                            MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
1354                            disk_name(gp, hd->partno, buf),
1355                            part_stat_read(hd, ios[READ]),
1356                            part_stat_read(hd, merges[READ]),
1357                            part_stat_read(hd, sectors[READ]),
1358                            jiffies_to_msecs(part_stat_read(hd, ticks[READ])),
1359                            part_stat_read(hd, ios[WRITE]),
1360                            part_stat_read(hd, merges[WRITE]),
1361                            part_stat_read(hd, sectors[WRITE]),
1362                            jiffies_to_msecs(part_stat_read(hd, ticks[WRITE])),
1363                            inflight[0],
1364                            jiffies_to_msecs(part_stat_read(hd, io_ticks)),
1365                            jiffies_to_msecs(part_stat_read(hd, time_in_queue))
1366                         );
1367         }
1368         disk_part_iter_exit(&piter);
1369 
1370         return 0;
1371 }
1372 
1373 static const struct seq_operations diskstats_op = {
1374         .start  = disk_seqf_start,
1375         .next   = disk_seqf_next,
1376         .stop   = disk_seqf_stop,
1377         .show   = diskstats_show
1378 };
1379 
1380 static int diskstats_open(struct inode *inode, struct file *file)
1381 {
1382         return seq_open(file, &diskstats_op);
1383 }
1384 
1385 static const struct file_operations proc_diskstats_operations = {
1386         .open           = diskstats_open,
1387         .read           = seq_read,
1388         .llseek         = seq_lseek,
1389         .release        = seq_release,
1390 };
1391 
1392 static int __init proc_genhd_init(void)
1393 {
1394         proc_create("diskstats", 0, NULL, &proc_diskstats_operations);
1395         proc_create("partitions", 0, NULL, &proc_partitions_operations);
1396         return 0;
1397 }
1398 module_init(proc_genhd_init);
1399 #endif /* CONFIG_PROC_FS */
1400 
1401 dev_t blk_lookup_devt(const char *name, int partno)
1402 {
1403         dev_t devt = MKDEV(0, 0);
1404         struct class_dev_iter iter;
1405         struct device *dev;
1406 
1407         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
1408         while ((dev = class_dev_iter_next(&iter))) {
1409                 struct gendisk *disk = dev_to_disk(dev);
1410                 struct hd_struct *part;
1411 
1412                 if (strcmp(dev_name(dev), name))
1413                         continue;
1414 
1415                 if (partno < disk->minors) {
1416                         /* We need to return the right devno, even
1417                          * if the partition doesn't exist yet.
1418                          */
1419                         devt = MKDEV(MAJOR(dev->devt),
1420                                      MINOR(dev->devt) + partno);
1421                         break;
1422                 }
1423                 part = disk_get_part(disk, partno);
1424                 if (part) {
1425                         devt = part_devt(part);
1426                         disk_put_part(part);
1427                         break;
1428                 }
1429                 disk_put_part(part);
1430         }
1431         class_dev_iter_exit(&iter);
1432         return devt;
1433 }
1434 EXPORT_SYMBOL(blk_lookup_devt);
1435 
1436 struct gendisk *__alloc_disk_node(int minors, int node_id)
1437 {
1438         struct gendisk *disk;
1439         struct disk_part_tbl *ptbl;
1440 
1441         if (minors > DISK_MAX_PARTS) {
1442                 printk(KERN_ERR
1443                         "block: can't allocate more than %d partitions\n",
1444                         DISK_MAX_PARTS);
1445                 minors = DISK_MAX_PARTS;
1446         }
1447 
1448         disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
1449         if (disk) {
1450                 if (!init_part_stats(&disk->part0)) {
1451                         kfree(disk);
1452                         return NULL;
1453                 }
1454                 init_rwsem(&disk->lookup_sem);
1455                 disk->node_id = node_id;
1456                 if (disk_expand_part_tbl(disk, 0)) {
1457                         free_part_stats(&disk->part0);
1458                         kfree(disk);
1459                         return NULL;
1460                 }
1461                 ptbl = rcu_dereference_protected(disk->part_tbl, 1);
1462                 rcu_assign_pointer(ptbl->part[0], &disk->part0);
1463 
1464                 /*
1465                  * set_capacity() and get_capacity() currently don't use
1466                  * seqcounter to read/update the part0->nr_sects. Still init
1467                  * the counter as we can read the sectors in IO submission
1468                  * patch using seqence counters.
1469                  *
1470                  * TODO: Ideally set_capacity() and get_capacity() should be
1471                  * converted to make use of bd_mutex and sequence counters.
1472                  */
1473                 seqcount_init(&disk->part0.nr_sects_seq);
1474                 if (hd_ref_init(&disk->part0)) {
1475                         hd_free_part(&disk->part0);
1476                         kfree(disk);
1477                         return NULL;
1478                 }
1479 
1480                 disk->minors = minors;
1481                 rand_initialize_disk(disk);
1482                 disk_to_dev(disk)->class = &block_class;
1483                 disk_to_dev(disk)->type = &disk_type;
1484                 device_initialize(disk_to_dev(disk));
1485         }
1486         return disk;
1487 }
1488 EXPORT_SYMBOL(__alloc_disk_node);
1489 
1490 struct kobject *get_disk_and_module(struct gendisk *disk)
1491 {
1492         struct module *owner;
1493         struct kobject *kobj;
1494 
1495         if (!disk->fops)
1496                 return NULL;
1497         owner = disk->fops->owner;
1498         if (owner && !try_module_get(owner))
1499                 return NULL;
1500         kobj = kobject_get_unless_zero(&disk_to_dev(disk)->kobj);
1501         if (kobj == NULL) {
1502                 module_put(owner);
1503                 return NULL;
1504         }
1505         return kobj;
1506 
1507 }
1508 EXPORT_SYMBOL(get_disk_and_module);
1509 
1510 void put_disk(struct gendisk *disk)
1511 {
1512         if (disk)
1513                 kobject_put(&disk_to_dev(disk)->kobj);
1514 }
1515 EXPORT_SYMBOL(put_disk);
1516 
1517 /*
1518  * This is a counterpart of get_disk_and_module() and thus also of
1519  * get_gendisk().
1520  */
1521 void put_disk_and_module(struct gendisk *disk)
1522 {
1523         if (disk) {
1524                 struct module *owner = disk->fops->owner;
1525 
1526                 put_disk(disk);
1527                 module_put(owner);
1528         }
1529 }
1530 EXPORT_SYMBOL(put_disk_and_module);
1531 
1532 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
1533 {
1534         char event[] = "DISK_RO=1";
1535         char *envp[] = { event, NULL };
1536 
1537         if (!ro)
1538                 event[8] = '';
1539         kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
1540 }
1541 
1542 void set_device_ro(struct block_device *bdev, int flag)
1543 {
1544         bdev->bd_part->policy = flag;
1545 }
1546 
1547 EXPORT_SYMBOL(set_device_ro);
1548 
1549 void set_disk_ro(struct gendisk *disk, int flag)
1550 {
1551         struct disk_part_iter piter;
1552         struct hd_struct *part;
1553 
1554         if (disk->part0.policy != flag) {
1555                 set_disk_ro_uevent(disk, flag);
1556                 disk->part0.policy = flag;
1557         }
1558 
1559         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
1560         while ((part = disk_part_iter_next(&piter)))
1561                 part->policy = flag;
1562         disk_part_iter_exit(&piter);
1563 }
1564 
1565 EXPORT_SYMBOL(set_disk_ro);
1566 
1567 int bdev_read_only(struct block_device *bdev)
1568 {
1569         if (!bdev)
1570                 return 0;
1571         return bdev->bd_part->policy;
1572 }
1573 
1574 EXPORT_SYMBOL(bdev_read_only);
1575 
1576 int invalidate_partition(struct gendisk *disk, int partno)
1577 {
1578         int res = 0;
1579         struct block_device *bdev = bdget_disk(disk, partno);
1580         if (bdev) {
1581                 fsync_bdev(bdev);
1582                 res = __invalidate_device(bdev, true);
1583                 bdput(bdev);
1584         }
1585         return res;
1586 }
1587 
1588 EXPORT_SYMBOL(invalidate_partition);
1589 
1590 /*
1591  * Disk events - monitor disk events like media change and eject request.
1592  */
1593 struct disk_events {
1594         struct list_head        node;           /* all disk_event's */
1595         struct gendisk          *disk;          /* the associated disk */
1596         spinlock_t              lock;
1597 
1598         struct mutex            block_mutex;    /* protects blocking */
1599         int                     block;          /* event blocking depth */
1600         unsigned int            pending;        /* events already sent out */
1601         unsigned int            clearing;       /* events being cleared */
1602 
1603         long                    poll_msecs;     /* interval, -1 for default */
1604         struct delayed_work     dwork;
1605 };
1606 
1607 static const char *disk_events_strs[] = {
1608         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "media_change",
1609         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "eject_request",
1610 };
1611 
1612 static char *disk_uevents[] = {
1613         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "DISK_MEDIA_CHANGE=1",
1614         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "DISK_EJECT_REQUEST=1",
1615 };
1616 
1617 /* list of all disk_events */
1618 static DEFINE_MUTEX(disk_events_mutex);
1619 static LIST_HEAD(disk_events);
1620 
1621 /* disable in-kernel polling by default */
1622 static unsigned long disk_events_dfl_poll_msecs;
1623 
1624 static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
1625 {
1626         struct disk_events *ev = disk->ev;
1627         long intv_msecs = 0;
1628 
1629         /*
1630          * If device-specific poll interval is set, always use it.  If
1631          * the default is being used, poll iff there are events which
1632          * can't be monitored asynchronously.
1633          */
1634         if (ev->poll_msecs >= 0)
1635                 intv_msecs = ev->poll_msecs;
1636         else if (disk->events & ~disk->async_events)
1637                 intv_msecs = disk_events_dfl_poll_msecs;
1638 
1639         return msecs_to_jiffies(intv_msecs);
1640 }
1641 
1642 /**
1643  * disk_block_events - block and flush disk event checking
1644  * @disk: disk to block events for
1645  *
1646  * On return from this function, it is guaranteed that event checking
1647  * isn't in progress and won't happen until unblocked by
1648  * disk_unblock_events().  Events blocking is counted and the actual
1649  * unblocking happens after the matching number of unblocks are done.
1650  *
1651  * Note that this intentionally does not block event checking from
1652  * disk_clear_events().
1653  *
1654  * CONTEXT:
1655  * Might sleep.
1656  */
1657 void disk_block_events(struct gendisk *disk)
1658 {
1659         struct disk_events *ev = disk->ev;
1660         unsigned long flags;
1661         bool cancel;
1662 
1663         if (!ev)
1664                 return;
1665 
1666         /*
1667          * Outer mutex ensures that the first blocker completes canceling
1668          * the event work before further blockers are allowed to finish.
1669          */
1670         mutex_lock(&ev->block_mutex);
1671 
1672         spin_lock_irqsave(&ev->lock, flags);
1673         cancel = !ev->block++;
1674         spin_unlock_irqrestore(&ev->lock, flags);
1675 
1676         if (cancel)
1677                 cancel_delayed_work_sync(&disk->ev->dwork);
1678 
1679         mutex_unlock(&ev->block_mutex);
1680 }
1681 
1682 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
1683 {
1684         struct disk_events *ev = disk->ev;
1685         unsigned long intv;
1686         unsigned long flags;
1687 
1688         spin_lock_irqsave(&ev->lock, flags);
1689 
1690         if (WARN_ON_ONCE(ev->block <= 0))
1691                 goto out_unlock;
1692 
1693         if (--ev->block)
1694                 goto out_unlock;
1695 
1696         intv = disk_events_poll_jiffies(disk);
1697         if (check_now)
1698                 queue_delayed_work(system_freezable_power_efficient_wq,
1699                                 &ev->dwork, 0);
1700         else if (intv)
1701                 queue_delayed_work(system_freezable_power_efficient_wq,
1702                                 &ev->dwork, intv);
1703 out_unlock:
1704         spin_unlock_irqrestore(&ev->lock, flags);
1705 }
1706 
1707 /**
1708  * disk_unblock_events - unblock disk event checking
1709  * @disk: disk to unblock events for
1710  *
1711  * Undo disk_block_events().  When the block count reaches zero, it
1712  * starts events polling if configured.
1713  *
1714  * CONTEXT:
1715  * Don't care.  Safe to call from irq context.
1716  */
1717 void disk_unblock_events(struct gendisk *disk)
1718 {
1719         if (disk->ev)
1720                 __disk_unblock_events(disk, false);
1721 }
1722 
1723 /**
1724  * disk_flush_events - schedule immediate event checking and flushing
1725  * @disk: disk to check and flush events for
1726  * @mask: events to flush
1727  *
1728  * Schedule immediate event checking on @disk if not blocked.  Events in
1729  * @mask are scheduled to be cleared from the driver.  Note that this
1730  * doesn't clear the events from @disk->ev.
1731  *
1732  * CONTEXT:
1733  * If @mask is non-zero must be called with bdev->bd_mutex held.
1734  */
1735 void disk_flush_events(struct gendisk *disk, unsigned int mask)
1736 {
1737         struct disk_events *ev = disk->ev;
1738 
1739         if (!ev)
1740                 return;
1741 
1742         spin_lock_irq(&ev->lock);
1743         ev->clearing |= mask;
1744         if (!ev->block)
1745                 mod_delayed_work(system_freezable_power_efficient_wq,
1746                                 &ev->dwork, 0);
1747         spin_unlock_irq(&ev->lock);
1748 }
1749 
1750 /**
1751  * disk_clear_events - synchronously check, clear and return pending events
1752  * @disk: disk to fetch and clear events from
1753  * @mask: mask of events to be fetched and cleared
1754  *
1755  * Disk events are synchronously checked and pending events in @mask
1756  * are cleared and returned.  This ignores the block count.
1757  *
1758  * CONTEXT:
1759  * Might sleep.
1760  */
1761 unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
1762 {
1763         const struct block_device_operations *bdops = disk->fops;
1764         struct disk_events *ev = disk->ev;
1765         unsigned int pending;
1766         unsigned int clearing = mask;
1767 
1768         if (!ev) {
1769                 /* for drivers still using the old ->media_changed method */
1770                 if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
1771                     bdops->media_changed && bdops->media_changed(disk))
1772                         return DISK_EVENT_MEDIA_CHANGE;
1773                 return 0;
1774         }
1775 
1776         disk_block_events(disk);
1777 
1778         /*
1779          * store the union of mask and ev->clearing on the stack so that the
1780          * race with disk_flush_events does not cause ambiguity (ev->clearing
1781          * can still be modified even if events are blocked).
1782          */
1783         spin_lock_irq(&ev->lock);
1784         clearing |= ev->clearing;
1785         ev->clearing = 0;
1786         spin_unlock_irq(&ev->lock);
1787 
1788         disk_check_events(ev, &clearing);
1789         /*
1790          * if ev->clearing is not 0, the disk_flush_events got called in the
1791          * middle of this function, so we want to run the workfn without delay.
1792          */
1793         __disk_unblock_events(disk, ev->clearing ? true : false);
1794 
1795         /* then, fetch and clear pending events */
1796         spin_lock_irq(&ev->lock);
1797         pending = ev->pending & mask;
1798         ev->pending &= ~mask;
1799         spin_unlock_irq(&ev->lock);
1800         WARN_ON_ONCE(clearing & mask);
1801 
1802         return pending;
1803 }
1804 
1805 /*
1806  * Separate this part out so that a different pointer for clearing_ptr can be
1807  * passed in for disk_clear_events.
1808  */
1809 static void disk_events_workfn(struct work_struct *work)
1810 {
1811         struct delayed_work *dwork = to_delayed_work(work);
1812         struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
1813 
1814         disk_check_events(ev, &ev->clearing);
1815 }
1816 
1817 static void disk_check_events(struct disk_events *ev,
1818                               unsigned int *clearing_ptr)
1819 {
1820         struct gendisk *disk = ev->disk;
1821         char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
1822         unsigned int clearing = *clearing_ptr;
1823         unsigned int events;
1824         unsigned long intv;
1825         int nr_events = 0, i;
1826 
1827         /* check events */
1828         events = disk->fops->check_events(disk, clearing);
1829 
1830         /* accumulate pending events and schedule next poll if necessary */
1831         spin_lock_irq(&ev->lock);
1832 
1833         events &= ~ev->pending;
1834         ev->pending |= events;
1835         *clearing_ptr &= ~clearing;
1836 
1837         intv = disk_events_poll_jiffies(disk);
1838         if (!ev->block && intv)
1839                 queue_delayed_work(system_freezable_power_efficient_wq,
1840                                 &ev->dwork, intv);
1841 
1842         spin_unlock_irq(&ev->lock);
1843 
1844         /*
1845          * Tell userland about new events.  Only the events listed in
1846          * @disk->events are reported.  Unlisted events are processed the
1847          * same internally but never get reported to userland.
1848          */
1849         for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
1850                 if (events & disk->events & (1 << i))
1851                         envp[nr_events++] = disk_uevents[i];
1852 
1853         if (nr_events)
1854                 kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
1855 }
1856 
1857 /*
1858  * A disk events enabled device has the following sysfs nodes under
1859  * its /sys/block/X/ directory.
1860  *
1861  * events               : list of all supported events
1862  * events_async         : list of events which can be detected w/o polling
1863  * events_poll_msecs    : polling interval, 0: disable, -1: system default
1864  */
1865 static ssize_t __disk_events_show(unsigned int events, char *buf)
1866 {
1867         const char *delim = "";
1868         ssize_t pos = 0;
1869         int i;
1870 
1871         for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
1872                 if (events & (1 << i)) {
1873                         pos += sprintf(buf + pos, "%s%s",
1874                                        delim, disk_events_strs[i]);
1875                         delim = " ";
1876                 }
1877         if (pos)
1878                 pos += sprintf(buf + pos, "\n");
1879         return pos;
1880 }
1881 
1882 static ssize_t disk_events_show(struct device *dev,
1883                                 struct device_attribute *attr, char *buf)
1884 {
1885         struct gendisk *disk = dev_to_disk(dev);
1886 
1887         return __disk_events_show(disk->events, buf);
1888 }
1889 
1890 static ssize_t disk_events_async_show(struct device *dev,
1891                                       struct device_attribute *attr, char *buf)
1892 {
1893         struct gendisk *disk = dev_to_disk(dev);
1894 
1895         return __disk_events_show(disk->async_events, buf);
1896 }
1897 
1898 static ssize_t disk_events_poll_msecs_show(struct device *dev,
1899                                            struct device_attribute *attr,
1900                                            char *buf)
1901 {
1902         struct gendisk *disk = dev_to_disk(dev);
1903 
1904         return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
1905 }
1906 
1907 static ssize_t disk_events_poll_msecs_store(struct device *dev,
1908                                             struct device_attribute *attr,
1909                                             const char *buf, size_t count)
1910 {
1911         struct gendisk *disk = dev_to_disk(dev);
1912         long intv;
1913 
1914         if (!count || !sscanf(buf, "%ld", &intv))
1915                 return -EINVAL;
1916 
1917         if (intv < 0 && intv != -1)
1918                 return -EINVAL;
1919 
1920         disk_block_events(disk);
1921         disk->ev->poll_msecs = intv;
1922         __disk_unblock_events(disk, true);
1923 
1924         return count;
1925 }
1926 
1927 static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
1928 static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
1929 static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
1930                          disk_events_poll_msecs_show,
1931                          disk_events_poll_msecs_store);
1932 
1933 static const struct attribute *disk_events_attrs[] = {
1934         &dev_attr_events.attr,
1935         &dev_attr_events_async.attr,
1936         &dev_attr_events_poll_msecs.attr,
1937         NULL,
1938 };
1939 
1940 /*
1941  * The default polling interval can be specified by the kernel
1942  * parameter block.events_dfl_poll_msecs which defaults to 0
1943  * (disable).  This can also be modified runtime by writing to
1944  * /sys/module/block/events_dfl_poll_msecs.
1945  */
1946 static int disk_events_set_dfl_poll_msecs(const char *val,
1947                                           const struct kernel_param *kp)
1948 {
1949         struct disk_events *ev;
1950         int ret;
1951 
1952         ret = param_set_ulong(val, kp);
1953         if (ret < 0)
1954                 return ret;
1955 
1956         mutex_lock(&disk_events_mutex);
1957 
1958         list_for_each_entry(ev, &disk_events, node)
1959                 disk_flush_events(ev->disk, 0);
1960 
1961         mutex_unlock(&disk_events_mutex);
1962 
1963         return 0;
1964 }
1965 
1966 static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
1967         .set    = disk_events_set_dfl_poll_msecs,
1968         .get    = param_get_ulong,
1969 };
1970 
1971 #undef MODULE_PARAM_PREFIX
1972 #define MODULE_PARAM_PREFIX     "block."
1973 
1974 module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
1975                 &disk_events_dfl_poll_msecs, 0644);
1976 
1977 /*
1978  * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
1979  */
1980 static void disk_alloc_events(struct gendisk *disk)
1981 {
1982         struct disk_events *ev;
1983 
1984         if (!disk->fops->check_events)
1985                 return;
1986 
1987         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
1988         if (!ev) {
1989                 pr_warn("%s: failed to initialize events\n", disk->disk_name);
1990                 return;
1991         }
1992 
1993         INIT_LIST_HEAD(&ev->node);
1994         ev->disk = disk;
1995         spin_lock_init(&ev->lock);
1996         mutex_init(&ev->block_mutex);
1997         ev->block = 1;
1998         ev->poll_msecs = -1;
1999         INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
2000 
2001         disk->ev = ev;
2002 }
2003 
2004 static void disk_add_events(struct gendisk *disk)
2005 {
2006         if (!disk->ev)
2007                 return;
2008 
2009         /* FIXME: error handling */
2010         if (sysfs_create_files(&disk_to_dev(disk)->kobj, disk_events_attrs) < 0)
2011                 pr_warn("%s: failed to create sysfs files for events\n",
2012                         disk->disk_name);
2013 
2014         mutex_lock(&disk_events_mutex);
2015         list_add_tail(&disk->ev->node, &disk_events);
2016         mutex_unlock(&disk_events_mutex);
2017 
2018         /*
2019          * Block count is initialized to 1 and the following initial
2020          * unblock kicks it into action.
2021          */
2022         __disk_unblock_events(disk, true);
2023 }
2024 
2025 static void disk_del_events(struct gendisk *disk)
2026 {
2027         if (!disk->ev)
2028                 return;
2029 
2030         disk_block_events(disk);
2031 
2032         mutex_lock(&disk_events_mutex);
2033         list_del_init(&disk->ev->node);
2034         mutex_unlock(&disk_events_mutex);
2035 
2036         sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
2037 }
2038 
2039 static void disk_release_events(struct gendisk *disk)
2040 {
2041         /* the block count should be 1 from disk_del_events() */
2042         WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
2043         kfree(disk->ev);
2044 }
2045 

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