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TOMOYO Linux Cross Reference
Linux/block/genhd.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  gendisk handling
  4  */
  5 
  6 #include <linux/module.h>
  7 #include <linux/fs.h>
  8 #include <linux/genhd.h>
  9 #include <linux/kdev_t.h>
 10 #include <linux/kernel.h>
 11 #include <linux/blkdev.h>
 12 #include <linux/backing-dev.h>
 13 #include <linux/init.h>
 14 #include <linux/spinlock.h>
 15 #include <linux/proc_fs.h>
 16 #include <linux/seq_file.h>
 17 #include <linux/slab.h>
 18 #include <linux/kmod.h>
 19 #include <linux/kobj_map.h>
 20 #include <linux/mutex.h>
 21 #include <linux/idr.h>
 22 #include <linux/log2.h>
 23 #include <linux/pm_runtime.h>
 24 #include <linux/badblocks.h>
 25 
 26 #include "blk.h"
 27 
 28 static DEFINE_MUTEX(block_class_lock);
 29 struct kobject *block_depr;
 30 
 31 /* for extended dynamic devt allocation, currently only one major is used */
 32 #define NR_EXT_DEVT             (1 << MINORBITS)
 33 
 34 /* For extended devt allocation.  ext_devt_lock prevents look up
 35  * results from going away underneath its user.
 36  */
 37 static DEFINE_SPINLOCK(ext_devt_lock);
 38 static DEFINE_IDR(ext_devt_idr);
 39 
 40 static const struct device_type disk_type;
 41 
 42 static void disk_check_events(struct disk_events *ev,
 43                               unsigned int *clearing_ptr);
 44 static void disk_alloc_events(struct gendisk *disk);
 45 static void disk_add_events(struct gendisk *disk);
 46 static void disk_del_events(struct gendisk *disk);
 47 static void disk_release_events(struct gendisk *disk);
 48 
 49 void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int rw)
 50 {
 51         if (queue_is_mq(q))
 52                 return;
 53 
 54         part_stat_local_inc(part, in_flight[rw]);
 55         if (part->partno)
 56                 part_stat_local_inc(&part_to_disk(part)->part0, in_flight[rw]);
 57 }
 58 
 59 void part_dec_in_flight(struct request_queue *q, struct hd_struct *part, int rw)
 60 {
 61         if (queue_is_mq(q))
 62                 return;
 63 
 64         part_stat_local_dec(part, in_flight[rw]);
 65         if (part->partno)
 66                 part_stat_local_dec(&part_to_disk(part)->part0, in_flight[rw]);
 67 }
 68 
 69 unsigned int part_in_flight(struct request_queue *q, struct hd_struct *part)
 70 {
 71         int cpu;
 72         unsigned int inflight;
 73 
 74         if (queue_is_mq(q)) {
 75                 return blk_mq_in_flight(q, part);
 76         }
 77 
 78         inflight = 0;
 79         for_each_possible_cpu(cpu) {
 80                 inflight += part_stat_local_read_cpu(part, in_flight[0], cpu) +
 81                             part_stat_local_read_cpu(part, in_flight[1], cpu);
 82         }
 83         if ((int)inflight < 0)
 84                 inflight = 0;
 85 
 86         return inflight;
 87 }
 88 
 89 void part_in_flight_rw(struct request_queue *q, struct hd_struct *part,
 90                        unsigned int inflight[2])
 91 {
 92         int cpu;
 93 
 94         if (queue_is_mq(q)) {
 95                 blk_mq_in_flight_rw(q, part, inflight);
 96                 return;
 97         }
 98 
 99         inflight[0] = 0;
100         inflight[1] = 0;
101         for_each_possible_cpu(cpu) {
102                 inflight[0] += part_stat_local_read_cpu(part, in_flight[0], cpu);
103                 inflight[1] += part_stat_local_read_cpu(part, in_flight[1], cpu);
104         }
105         if ((int)inflight[0] < 0)
106                 inflight[0] = 0;
107         if ((int)inflight[1] < 0)
108                 inflight[1] = 0;
109 }
110 
111 struct hd_struct *__disk_get_part(struct gendisk *disk, int partno)
112 {
113         struct disk_part_tbl *ptbl = rcu_dereference(disk->part_tbl);
114 
115         if (unlikely(partno < 0 || partno >= ptbl->len))
116                 return NULL;
117         return rcu_dereference(ptbl->part[partno]);
118 }
119 
120 /**
121  * disk_get_part - get partition
122  * @disk: disk to look partition from
123  * @partno: partition number
124  *
125  * Look for partition @partno from @disk.  If found, increment
126  * reference count and return it.
127  *
128  * CONTEXT:
129  * Don't care.
130  *
131  * RETURNS:
132  * Pointer to the found partition on success, NULL if not found.
133  */
134 struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
135 {
136         struct hd_struct *part;
137 
138         rcu_read_lock();
139         part = __disk_get_part(disk, partno);
140         if (part)
141                 get_device(part_to_dev(part));
142         rcu_read_unlock();
143 
144         return part;
145 }
146 EXPORT_SYMBOL_GPL(disk_get_part);
147 
148 /**
149  * disk_part_iter_init - initialize partition iterator
150  * @piter: iterator to initialize
151  * @disk: disk to iterate over
152  * @flags: DISK_PITER_* flags
153  *
154  * Initialize @piter so that it iterates over partitions of @disk.
155  *
156  * CONTEXT:
157  * Don't care.
158  */
159 void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
160                           unsigned int flags)
161 {
162         struct disk_part_tbl *ptbl;
163 
164         rcu_read_lock();
165         ptbl = rcu_dereference(disk->part_tbl);
166 
167         piter->disk = disk;
168         piter->part = NULL;
169 
170         if (flags & DISK_PITER_REVERSE)
171                 piter->idx = ptbl->len - 1;
172         else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
173                 piter->idx = 0;
174         else
175                 piter->idx = 1;
176 
177         piter->flags = flags;
178 
179         rcu_read_unlock();
180 }
181 EXPORT_SYMBOL_GPL(disk_part_iter_init);
182 
183 /**
184  * disk_part_iter_next - proceed iterator to the next partition and return it
185  * @piter: iterator of interest
186  *
187  * Proceed @piter to the next partition and return it.
188  *
189  * CONTEXT:
190  * Don't care.
191  */
192 struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
193 {
194         struct disk_part_tbl *ptbl;
195         int inc, end;
196 
197         /* put the last partition */
198         disk_put_part(piter->part);
199         piter->part = NULL;
200 
201         /* get part_tbl */
202         rcu_read_lock();
203         ptbl = rcu_dereference(piter->disk->part_tbl);
204 
205         /* determine iteration parameters */
206         if (piter->flags & DISK_PITER_REVERSE) {
207                 inc = -1;
208                 if (piter->flags & (DISK_PITER_INCL_PART0 |
209                                     DISK_PITER_INCL_EMPTY_PART0))
210                         end = -1;
211                 else
212                         end = 0;
213         } else {
214                 inc = 1;
215                 end = ptbl->len;
216         }
217 
218         /* iterate to the next partition */
219         for (; piter->idx != end; piter->idx += inc) {
220                 struct hd_struct *part;
221 
222                 part = rcu_dereference(ptbl->part[piter->idx]);
223                 if (!part)
224                         continue;
225                 if (!part_nr_sects_read(part) &&
226                     !(piter->flags & DISK_PITER_INCL_EMPTY) &&
227                     !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
228                       piter->idx == 0))
229                         continue;
230 
231                 get_device(part_to_dev(part));
232                 piter->part = part;
233                 piter->idx += inc;
234                 break;
235         }
236 
237         rcu_read_unlock();
238 
239         return piter->part;
240 }
241 EXPORT_SYMBOL_GPL(disk_part_iter_next);
242 
243 /**
244  * disk_part_iter_exit - finish up partition iteration
245  * @piter: iter of interest
246  *
247  * Called when iteration is over.  Cleans up @piter.
248  *
249  * CONTEXT:
250  * Don't care.
251  */
252 void disk_part_iter_exit(struct disk_part_iter *piter)
253 {
254         disk_put_part(piter->part);
255         piter->part = NULL;
256 }
257 EXPORT_SYMBOL_GPL(disk_part_iter_exit);
258 
259 static inline int sector_in_part(struct hd_struct *part, sector_t sector)
260 {
261         return part->start_sect <= sector &&
262                 sector < part->start_sect + part_nr_sects_read(part);
263 }
264 
265 /**
266  * disk_map_sector_rcu - map sector to partition
267  * @disk: gendisk of interest
268  * @sector: sector to map
269  *
270  * Find out which partition @sector maps to on @disk.  This is
271  * primarily used for stats accounting.
272  *
273  * CONTEXT:
274  * RCU read locked.  The returned partition pointer is valid only
275  * while preemption is disabled.
276  *
277  * RETURNS:
278  * Found partition on success, part0 is returned if no partition matches
279  */
280 struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
281 {
282         struct disk_part_tbl *ptbl;
283         struct hd_struct *part;
284         int i;
285 
286         ptbl = rcu_dereference(disk->part_tbl);
287 
288         part = rcu_dereference(ptbl->last_lookup);
289         if (part && sector_in_part(part, sector))
290                 return part;
291 
292         for (i = 1; i < ptbl->len; i++) {
293                 part = rcu_dereference(ptbl->part[i]);
294 
295                 if (part && sector_in_part(part, sector)) {
296                         rcu_assign_pointer(ptbl->last_lookup, part);
297                         return part;
298                 }
299         }
300         return &disk->part0;
301 }
302 EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
303 
304 /*
305  * Can be deleted altogether. Later.
306  *
307  */
308 #define BLKDEV_MAJOR_HASH_SIZE 255
309 static struct blk_major_name {
310         struct blk_major_name *next;
311         int major;
312         char name[16];
313 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
314 
315 /* index in the above - for now: assume no multimajor ranges */
316 static inline int major_to_index(unsigned major)
317 {
318         return major % BLKDEV_MAJOR_HASH_SIZE;
319 }
320 
321 #ifdef CONFIG_PROC_FS
322 void blkdev_show(struct seq_file *seqf, off_t offset)
323 {
324         struct blk_major_name *dp;
325 
326         mutex_lock(&block_class_lock);
327         for (dp = major_names[major_to_index(offset)]; dp; dp = dp->next)
328                 if (dp->major == offset)
329                         seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
330         mutex_unlock(&block_class_lock);
331 }
332 #endif /* CONFIG_PROC_FS */
333 
334 /**
335  * register_blkdev - register a new block device
336  *
337  * @major: the requested major device number [1..BLKDEV_MAJOR_MAX-1]. If
338  *         @major = 0, try to allocate any unused major number.
339  * @name: the name of the new block device as a zero terminated string
340  *
341  * The @name must be unique within the system.
342  *
343  * The return value depends on the @major input parameter:
344  *
345  *  - if a major device number was requested in range [1..BLKDEV_MAJOR_MAX-1]
346  *    then the function returns zero on success, or a negative error code
347  *  - if any unused major number was requested with @major = 0 parameter
348  *    then the return value is the allocated major number in range
349  *    [1..BLKDEV_MAJOR_MAX-1] or a negative error code otherwise
350  *
351  * See Documentation/admin-guide/devices.txt for the list of allocated
352  * major numbers.
353  */
354 int register_blkdev(unsigned int major, const char *name)
355 {
356         struct blk_major_name **n, *p;
357         int index, ret = 0;
358 
359         mutex_lock(&block_class_lock);
360 
361         /* temporary */
362         if (major == 0) {
363                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
364                         if (major_names[index] == NULL)
365                                 break;
366                 }
367 
368                 if (index == 0) {
369                         printk("%s: failed to get major for %s\n",
370                                __func__, name);
371                         ret = -EBUSY;
372                         goto out;
373                 }
374                 major = index;
375                 ret = major;
376         }
377 
378         if (major >= BLKDEV_MAJOR_MAX) {
379                 pr_err("%s: major requested (%u) is greater than the maximum (%u) for %s\n",
380                        __func__, major, BLKDEV_MAJOR_MAX-1, name);
381 
382                 ret = -EINVAL;
383                 goto out;
384         }
385 
386         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
387         if (p == NULL) {
388                 ret = -ENOMEM;
389                 goto out;
390         }
391 
392         p->major = major;
393         strlcpy(p->name, name, sizeof(p->name));
394         p->next = NULL;
395         index = major_to_index(major);
396 
397         for (n = &major_names[index]; *n; n = &(*n)->next) {
398                 if ((*n)->major == major)
399                         break;
400         }
401         if (!*n)
402                 *n = p;
403         else
404                 ret = -EBUSY;
405 
406         if (ret < 0) {
407                 printk("register_blkdev: cannot get major %u for %s\n",
408                        major, name);
409                 kfree(p);
410         }
411 out:
412         mutex_unlock(&block_class_lock);
413         return ret;
414 }
415 
416 EXPORT_SYMBOL(register_blkdev);
417 
418 void unregister_blkdev(unsigned int major, const char *name)
419 {
420         struct blk_major_name **n;
421         struct blk_major_name *p = NULL;
422         int index = major_to_index(major);
423 
424         mutex_lock(&block_class_lock);
425         for (n = &major_names[index]; *n; n = &(*n)->next)
426                 if ((*n)->major == major)
427                         break;
428         if (!*n || strcmp((*n)->name, name)) {
429                 WARN_ON(1);
430         } else {
431                 p = *n;
432                 *n = p->next;
433         }
434         mutex_unlock(&block_class_lock);
435         kfree(p);
436 }
437 
438 EXPORT_SYMBOL(unregister_blkdev);
439 
440 static struct kobj_map *bdev_map;
441 
442 /**
443  * blk_mangle_minor - scatter minor numbers apart
444  * @minor: minor number to mangle
445  *
446  * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
447  * is enabled.  Mangling twice gives the original value.
448  *
449  * RETURNS:
450  * Mangled value.
451  *
452  * CONTEXT:
453  * Don't care.
454  */
455 static int blk_mangle_minor(int minor)
456 {
457 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
458         int i;
459 
460         for (i = 0; i < MINORBITS / 2; i++) {
461                 int low = minor & (1 << i);
462                 int high = minor & (1 << (MINORBITS - 1 - i));
463                 int distance = MINORBITS - 1 - 2 * i;
464 
465                 minor ^= low | high;    /* clear both bits */
466                 low <<= distance;       /* swap the positions */
467                 high >>= distance;
468                 minor |= low | high;    /* and set */
469         }
470 #endif
471         return minor;
472 }
473 
474 /**
475  * blk_alloc_devt - allocate a dev_t for a partition
476  * @part: partition to allocate dev_t for
477  * @devt: out parameter for resulting dev_t
478  *
479  * Allocate a dev_t for block device.
480  *
481  * RETURNS:
482  * 0 on success, allocated dev_t is returned in *@devt.  -errno on
483  * failure.
484  *
485  * CONTEXT:
486  * Might sleep.
487  */
488 int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
489 {
490         struct gendisk *disk = part_to_disk(part);
491         int idx;
492 
493         /* in consecutive minor range? */
494         if (part->partno < disk->minors) {
495                 *devt = MKDEV(disk->major, disk->first_minor + part->partno);
496                 return 0;
497         }
498 
499         /* allocate ext devt */
500         idr_preload(GFP_KERNEL);
501 
502         spin_lock_bh(&ext_devt_lock);
503         idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);
504         spin_unlock_bh(&ext_devt_lock);
505 
506         idr_preload_end();
507         if (idx < 0)
508                 return idx == -ENOSPC ? -EBUSY : idx;
509 
510         *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
511         return 0;
512 }
513 
514 /**
515  * blk_free_devt - free a dev_t
516  * @devt: dev_t to free
517  *
518  * Free @devt which was allocated using blk_alloc_devt().
519  *
520  * CONTEXT:
521  * Might sleep.
522  */
523 void blk_free_devt(dev_t devt)
524 {
525         if (devt == MKDEV(0, 0))
526                 return;
527 
528         if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
529                 spin_lock_bh(&ext_devt_lock);
530                 idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
531                 spin_unlock_bh(&ext_devt_lock);
532         }
533 }
534 
535 /*
536  * We invalidate devt by assigning NULL pointer for devt in idr.
537  */
538 void blk_invalidate_devt(dev_t devt)
539 {
540         if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
541                 spin_lock_bh(&ext_devt_lock);
542                 idr_replace(&ext_devt_idr, NULL, blk_mangle_minor(MINOR(devt)));
543                 spin_unlock_bh(&ext_devt_lock);
544         }
545 }
546 
547 static char *bdevt_str(dev_t devt, char *buf)
548 {
549         if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
550                 char tbuf[BDEVT_SIZE];
551                 snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
552                 snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
553         } else
554                 snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
555 
556         return buf;
557 }
558 
559 /*
560  * Register device numbers dev..(dev+range-1)
561  * range must be nonzero
562  * The hash chain is sorted on range, so that subranges can override.
563  */
564 void blk_register_region(dev_t devt, unsigned long range, struct module *module,
565                          struct kobject *(*probe)(dev_t, int *, void *),
566                          int (*lock)(dev_t, void *), void *data)
567 {
568         kobj_map(bdev_map, devt, range, module, probe, lock, data);
569 }
570 
571 EXPORT_SYMBOL(blk_register_region);
572 
573 void blk_unregister_region(dev_t devt, unsigned long range)
574 {
575         kobj_unmap(bdev_map, devt, range);
576 }
577 
578 EXPORT_SYMBOL(blk_unregister_region);
579 
580 static struct kobject *exact_match(dev_t devt, int *partno, void *data)
581 {
582         struct gendisk *p = data;
583 
584         return &disk_to_dev(p)->kobj;
585 }
586 
587 static int exact_lock(dev_t devt, void *data)
588 {
589         struct gendisk *p = data;
590 
591         if (!get_disk_and_module(p))
592                 return -1;
593         return 0;
594 }
595 
596 static void register_disk(struct device *parent, struct gendisk *disk,
597                           const struct attribute_group **groups)
598 {
599         struct device *ddev = disk_to_dev(disk);
600         struct block_device *bdev;
601         struct disk_part_iter piter;
602         struct hd_struct *part;
603         int err;
604 
605         ddev->parent = parent;
606 
607         dev_set_name(ddev, "%s", disk->disk_name);
608 
609         /* delay uevents, until we scanned partition table */
610         dev_set_uevent_suppress(ddev, 1);
611 
612         if (groups) {
613                 WARN_ON(ddev->groups);
614                 ddev->groups = groups;
615         }
616         if (device_add(ddev))
617                 return;
618         if (!sysfs_deprecated) {
619                 err = sysfs_create_link(block_depr, &ddev->kobj,
620                                         kobject_name(&ddev->kobj));
621                 if (err) {
622                         device_del(ddev);
623                         return;
624                 }
625         }
626 
627         /*
628          * avoid probable deadlock caused by allocating memory with
629          * GFP_KERNEL in runtime_resume callback of its all ancestor
630          * devices
631          */
632         pm_runtime_set_memalloc_noio(ddev, true);
633 
634         disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
635         disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
636 
637         if (disk->flags & GENHD_FL_HIDDEN) {
638                 dev_set_uevent_suppress(ddev, 0);
639                 return;
640         }
641 
642         /* No minors to use for partitions */
643         if (!disk_part_scan_enabled(disk))
644                 goto exit;
645 
646         /* No such device (e.g., media were just removed) */
647         if (!get_capacity(disk))
648                 goto exit;
649 
650         bdev = bdget_disk(disk, 0);
651         if (!bdev)
652                 goto exit;
653 
654         bdev->bd_invalidated = 1;
655         err = blkdev_get(bdev, FMODE_READ, NULL);
656         if (err < 0)
657                 goto exit;
658         blkdev_put(bdev, FMODE_READ);
659 
660 exit:
661         /* announce disk after possible partitions are created */
662         dev_set_uevent_suppress(ddev, 0);
663         kobject_uevent(&ddev->kobj, KOBJ_ADD);
664 
665         /* announce possible partitions */
666         disk_part_iter_init(&piter, disk, 0);
667         while ((part = disk_part_iter_next(&piter)))
668                 kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
669         disk_part_iter_exit(&piter);
670 
671         if (disk->queue->backing_dev_info->dev) {
672                 err = sysfs_create_link(&ddev->kobj,
673                           &disk->queue->backing_dev_info->dev->kobj,
674                           "bdi");
675                 WARN_ON(err);
676         }
677 }
678 
679 /**
680  * __device_add_disk - add disk information to kernel list
681  * @parent: parent device for the disk
682  * @disk: per-device partitioning information
683  * @groups: Additional per-device sysfs groups
684  * @register_queue: register the queue if set to true
685  *
686  * This function registers the partitioning information in @disk
687  * with the kernel.
688  *
689  * FIXME: error handling
690  */
691 static void __device_add_disk(struct device *parent, struct gendisk *disk,
692                               const struct attribute_group **groups,
693                               bool register_queue)
694 {
695         dev_t devt;
696         int retval;
697 
698         /* minors == 0 indicates to use ext devt from part0 and should
699          * be accompanied with EXT_DEVT flag.  Make sure all
700          * parameters make sense.
701          */
702         WARN_ON(disk->minors && !(disk->major || disk->first_minor));
703         WARN_ON(!disk->minors &&
704                 !(disk->flags & (GENHD_FL_EXT_DEVT | GENHD_FL_HIDDEN)));
705 
706         disk->flags |= GENHD_FL_UP;
707 
708         retval = blk_alloc_devt(&disk->part0, &devt);
709         if (retval) {
710                 WARN_ON(1);
711                 return;
712         }
713         disk->major = MAJOR(devt);
714         disk->first_minor = MINOR(devt);
715 
716         disk_alloc_events(disk);
717 
718         if (disk->flags & GENHD_FL_HIDDEN) {
719                 /*
720                  * Don't let hidden disks show up in /proc/partitions,
721                  * and don't bother scanning for partitions either.
722                  */
723                 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
724                 disk->flags |= GENHD_FL_NO_PART_SCAN;
725         } else {
726                 int ret;
727 
728                 /* Register BDI before referencing it from bdev */
729                 disk_to_dev(disk)->devt = devt;
730                 ret = bdi_register_owner(disk->queue->backing_dev_info,
731                                                 disk_to_dev(disk));
732                 WARN_ON(ret);
733                 blk_register_region(disk_devt(disk), disk->minors, NULL,
734                                     exact_match, exact_lock, disk);
735         }
736         register_disk(parent, disk, groups);
737         if (register_queue)
738                 blk_register_queue(disk);
739 
740         /*
741          * Take an extra ref on queue which will be put on disk_release()
742          * so that it sticks around as long as @disk is there.
743          */
744         WARN_ON_ONCE(!blk_get_queue(disk->queue));
745 
746         disk_add_events(disk);
747         blk_integrity_add(disk);
748 }
749 
750 void device_add_disk(struct device *parent, struct gendisk *disk,
751                      const struct attribute_group **groups)
752 
753 {
754         __device_add_disk(parent, disk, groups, true);
755 }
756 EXPORT_SYMBOL(device_add_disk);
757 
758 void device_add_disk_no_queue_reg(struct device *parent, struct gendisk *disk)
759 {
760         __device_add_disk(parent, disk, NULL, false);
761 }
762 EXPORT_SYMBOL(device_add_disk_no_queue_reg);
763 
764 void del_gendisk(struct gendisk *disk)
765 {
766         struct disk_part_iter piter;
767         struct hd_struct *part;
768 
769         blk_integrity_del(disk);
770         disk_del_events(disk);
771 
772         /*
773          * Block lookups of the disk until all bdevs are unhashed and the
774          * disk is marked as dead (GENHD_FL_UP cleared).
775          */
776         down_write(&disk->lookup_sem);
777         /* invalidate stuff */
778         disk_part_iter_init(&piter, disk,
779                              DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
780         while ((part = disk_part_iter_next(&piter))) {
781                 invalidate_partition(disk, part->partno);
782                 bdev_unhash_inode(part_devt(part));
783                 delete_partition(disk, part->partno);
784         }
785         disk_part_iter_exit(&piter);
786 
787         invalidate_partition(disk, 0);
788         bdev_unhash_inode(disk_devt(disk));
789         set_capacity(disk, 0);
790         disk->flags &= ~GENHD_FL_UP;
791         up_write(&disk->lookup_sem);
792 
793         if (!(disk->flags & GENHD_FL_HIDDEN))
794                 sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
795         if (disk->queue) {
796                 /*
797                  * Unregister bdi before releasing device numbers (as they can
798                  * get reused and we'd get clashes in sysfs).
799                  */
800                 if (!(disk->flags & GENHD_FL_HIDDEN))
801                         bdi_unregister(disk->queue->backing_dev_info);
802                 blk_unregister_queue(disk);
803         } else {
804                 WARN_ON(1);
805         }
806 
807         if (!(disk->flags & GENHD_FL_HIDDEN))
808                 blk_unregister_region(disk_devt(disk), disk->minors);
809         /*
810          * Remove gendisk pointer from idr so that it cannot be looked up
811          * while RCU period before freeing gendisk is running to prevent
812          * use-after-free issues. Note that the device number stays
813          * "in-use" until we really free the gendisk.
814          */
815         blk_invalidate_devt(disk_devt(disk));
816 
817         kobject_put(disk->part0.holder_dir);
818         kobject_put(disk->slave_dir);
819 
820         part_stat_set_all(&disk->part0, 0);
821         disk->part0.stamp = 0;
822         if (!sysfs_deprecated)
823                 sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
824         pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
825         device_del(disk_to_dev(disk));
826 }
827 EXPORT_SYMBOL(del_gendisk);
828 
829 /* sysfs access to bad-blocks list. */
830 static ssize_t disk_badblocks_show(struct device *dev,
831                                         struct device_attribute *attr,
832                                         char *page)
833 {
834         struct gendisk *disk = dev_to_disk(dev);
835 
836         if (!disk->bb)
837                 return sprintf(page, "\n");
838 
839         return badblocks_show(disk->bb, page, 0);
840 }
841 
842 static ssize_t disk_badblocks_store(struct device *dev,
843                                         struct device_attribute *attr,
844                                         const char *page, size_t len)
845 {
846         struct gendisk *disk = dev_to_disk(dev);
847 
848         if (!disk->bb)
849                 return -ENXIO;
850 
851         return badblocks_store(disk->bb, page, len, 0);
852 }
853 
854 /**
855  * get_gendisk - get partitioning information for a given device
856  * @devt: device to get partitioning information for
857  * @partno: returned partition index
858  *
859  * This function gets the structure containing partitioning
860  * information for the given device @devt.
861  */
862 struct gendisk *get_gendisk(dev_t devt, int *partno)
863 {
864         struct gendisk *disk = NULL;
865 
866         if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
867                 struct kobject *kobj;
868 
869                 kobj = kobj_lookup(bdev_map, devt, partno);
870                 if (kobj)
871                         disk = dev_to_disk(kobj_to_dev(kobj));
872         } else {
873                 struct hd_struct *part;
874 
875                 spin_lock_bh(&ext_devt_lock);
876                 part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
877                 if (part && get_disk_and_module(part_to_disk(part))) {
878                         *partno = part->partno;
879                         disk = part_to_disk(part);
880                 }
881                 spin_unlock_bh(&ext_devt_lock);
882         }
883 
884         if (!disk)
885                 return NULL;
886 
887         /*
888          * Synchronize with del_gendisk() to not return disk that is being
889          * destroyed.
890          */
891         down_read(&disk->lookup_sem);
892         if (unlikely((disk->flags & GENHD_FL_HIDDEN) ||
893                      !(disk->flags & GENHD_FL_UP))) {
894                 up_read(&disk->lookup_sem);
895                 put_disk_and_module(disk);
896                 disk = NULL;
897         } else {
898                 up_read(&disk->lookup_sem);
899         }
900         return disk;
901 }
902 EXPORT_SYMBOL(get_gendisk);
903 
904 /**
905  * bdget_disk - do bdget() by gendisk and partition number
906  * @disk: gendisk of interest
907  * @partno: partition number
908  *
909  * Find partition @partno from @disk, do bdget() on it.
910  *
911  * CONTEXT:
912  * Don't care.
913  *
914  * RETURNS:
915  * Resulting block_device on success, NULL on failure.
916  */
917 struct block_device *bdget_disk(struct gendisk *disk, int partno)
918 {
919         struct hd_struct *part;
920         struct block_device *bdev = NULL;
921 
922         part = disk_get_part(disk, partno);
923         if (part)
924                 bdev = bdget(part_devt(part));
925         disk_put_part(part);
926 
927         return bdev;
928 }
929 EXPORT_SYMBOL(bdget_disk);
930 
931 /*
932  * print a full list of all partitions - intended for places where the root
933  * filesystem can't be mounted and thus to give the victim some idea of what
934  * went wrong
935  */
936 void __init printk_all_partitions(void)
937 {
938         struct class_dev_iter iter;
939         struct device *dev;
940 
941         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
942         while ((dev = class_dev_iter_next(&iter))) {
943                 struct gendisk *disk = dev_to_disk(dev);
944                 struct disk_part_iter piter;
945                 struct hd_struct *part;
946                 char name_buf[BDEVNAME_SIZE];
947                 char devt_buf[BDEVT_SIZE];
948 
949                 /*
950                  * Don't show empty devices or things that have been
951                  * suppressed
952                  */
953                 if (get_capacity(disk) == 0 ||
954                     (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
955                         continue;
956 
957                 /*
958                  * Note, unlike /proc/partitions, I am showing the
959                  * numbers in hex - the same format as the root=
960                  * option takes.
961                  */
962                 disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
963                 while ((part = disk_part_iter_next(&piter))) {
964                         bool is_part0 = part == &disk->part0;
965 
966                         printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
967                                bdevt_str(part_devt(part), devt_buf),
968                                (unsigned long long)part_nr_sects_read(part) >> 1
969                                , disk_name(disk, part->partno, name_buf),
970                                part->info ? part->info->uuid : "");
971                         if (is_part0) {
972                                 if (dev->parent && dev->parent->driver)
973                                         printk(" driver: %s\n",
974                                               dev->parent->driver->name);
975                                 else
976                                         printk(" (driver?)\n");
977                         } else
978                                 printk("\n");
979                 }
980                 disk_part_iter_exit(&piter);
981         }
982         class_dev_iter_exit(&iter);
983 }
984 
985 #ifdef CONFIG_PROC_FS
986 /* iterator */
987 static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
988 {
989         loff_t skip = *pos;
990         struct class_dev_iter *iter;
991         struct device *dev;
992 
993         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
994         if (!iter)
995                 return ERR_PTR(-ENOMEM);
996 
997         seqf->private = iter;
998         class_dev_iter_init(iter, &block_class, NULL, &disk_type);
999         do {
1000                 dev = class_dev_iter_next(iter);
1001                 if (!dev)
1002                         return NULL;
1003         } while (skip--);
1004 
1005         return dev_to_disk(dev);
1006 }
1007 
1008 static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
1009 {
1010         struct device *dev;
1011 
1012         (*pos)++;
1013         dev = class_dev_iter_next(seqf->private);
1014         if (dev)
1015                 return dev_to_disk(dev);
1016 
1017         return NULL;
1018 }
1019 
1020 static void disk_seqf_stop(struct seq_file *seqf, void *v)
1021 {
1022         struct class_dev_iter *iter = seqf->private;
1023 
1024         /* stop is called even after start failed :-( */
1025         if (iter) {
1026                 class_dev_iter_exit(iter);
1027                 kfree(iter);
1028                 seqf->private = NULL;
1029         }
1030 }
1031 
1032 static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
1033 {
1034         void *p;
1035 
1036         p = disk_seqf_start(seqf, pos);
1037         if (!IS_ERR_OR_NULL(p) && !*pos)
1038                 seq_puts(seqf, "major minor  #blocks  name\n\n");
1039         return p;
1040 }
1041 
1042 static int show_partition(struct seq_file *seqf, void *v)
1043 {
1044         struct gendisk *sgp = v;
1045         struct disk_part_iter piter;
1046         struct hd_struct *part;
1047         char buf[BDEVNAME_SIZE];
1048 
1049         /* Don't show non-partitionable removeable devices or empty devices */
1050         if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
1051                                    (sgp->flags & GENHD_FL_REMOVABLE)))
1052                 return 0;
1053         if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
1054                 return 0;
1055 
1056         /* show the full disk and all non-0 size partitions of it */
1057         disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
1058         while ((part = disk_part_iter_next(&piter)))
1059                 seq_printf(seqf, "%4d  %7d %10llu %s\n",
1060                            MAJOR(part_devt(part)), MINOR(part_devt(part)),
1061                            (unsigned long long)part_nr_sects_read(part) >> 1,
1062                            disk_name(sgp, part->partno, buf));
1063         disk_part_iter_exit(&piter);
1064 
1065         return 0;
1066 }
1067 
1068 static const struct seq_operations partitions_op = {
1069         .start  = show_partition_start,
1070         .next   = disk_seqf_next,
1071         .stop   = disk_seqf_stop,
1072         .show   = show_partition
1073 };
1074 #endif
1075 
1076 
1077 static struct kobject *base_probe(dev_t devt, int *partno, void *data)
1078 {
1079         if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
1080                 /* Make old-style 2.4 aliases work */
1081                 request_module("block-major-%d", MAJOR(devt));
1082         return NULL;
1083 }
1084 
1085 static int __init genhd_device_init(void)
1086 {
1087         int error;
1088 
1089         block_class.dev_kobj = sysfs_dev_block_kobj;
1090         error = class_register(&block_class);
1091         if (unlikely(error))
1092                 return error;
1093         bdev_map = kobj_map_init(base_probe, &block_class_lock);
1094         blk_dev_init();
1095 
1096         register_blkdev(BLOCK_EXT_MAJOR, "blkext");
1097 
1098         /* create top-level block dir */
1099         if (!sysfs_deprecated)
1100                 block_depr = kobject_create_and_add("block", NULL);
1101         return 0;
1102 }
1103 
1104 subsys_initcall(genhd_device_init);
1105 
1106 static ssize_t disk_range_show(struct device *dev,
1107                                struct device_attribute *attr, char *buf)
1108 {
1109         struct gendisk *disk = dev_to_disk(dev);
1110 
1111         return sprintf(buf, "%d\n", disk->minors);
1112 }
1113 
1114 static ssize_t disk_ext_range_show(struct device *dev,
1115                                    struct device_attribute *attr, char *buf)
1116 {
1117         struct gendisk *disk = dev_to_disk(dev);
1118 
1119         return sprintf(buf, "%d\n", disk_max_parts(disk));
1120 }
1121 
1122 static ssize_t disk_removable_show(struct device *dev,
1123                                    struct device_attribute *attr, char *buf)
1124 {
1125         struct gendisk *disk = dev_to_disk(dev);
1126 
1127         return sprintf(buf, "%d\n",
1128                        (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
1129 }
1130 
1131 static ssize_t disk_hidden_show(struct device *dev,
1132                                    struct device_attribute *attr, char *buf)
1133 {
1134         struct gendisk *disk = dev_to_disk(dev);
1135 
1136         return sprintf(buf, "%d\n",
1137                        (disk->flags & GENHD_FL_HIDDEN ? 1 : 0));
1138 }
1139 
1140 static ssize_t disk_ro_show(struct device *dev,
1141                                    struct device_attribute *attr, char *buf)
1142 {
1143         struct gendisk *disk = dev_to_disk(dev);
1144 
1145         return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
1146 }
1147 
1148 static ssize_t disk_capability_show(struct device *dev,
1149                                     struct device_attribute *attr, char *buf)
1150 {
1151         struct gendisk *disk = dev_to_disk(dev);
1152 
1153         return sprintf(buf, "%x\n", disk->flags);
1154 }
1155 
1156 static ssize_t disk_alignment_offset_show(struct device *dev,
1157                                           struct device_attribute *attr,
1158                                           char *buf)
1159 {
1160         struct gendisk *disk = dev_to_disk(dev);
1161 
1162         return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
1163 }
1164 
1165 static ssize_t disk_discard_alignment_show(struct device *dev,
1166                                            struct device_attribute *attr,
1167                                            char *buf)
1168 {
1169         struct gendisk *disk = dev_to_disk(dev);
1170 
1171         return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));
1172 }
1173 
1174 static DEVICE_ATTR(range, 0444, disk_range_show, NULL);
1175 static DEVICE_ATTR(ext_range, 0444, disk_ext_range_show, NULL);
1176 static DEVICE_ATTR(removable, 0444, disk_removable_show, NULL);
1177 static DEVICE_ATTR(hidden, 0444, disk_hidden_show, NULL);
1178 static DEVICE_ATTR(ro, 0444, disk_ro_show, NULL);
1179 static DEVICE_ATTR(size, 0444, part_size_show, NULL);
1180 static DEVICE_ATTR(alignment_offset, 0444, disk_alignment_offset_show, NULL);
1181 static DEVICE_ATTR(discard_alignment, 0444, disk_discard_alignment_show, NULL);
1182 static DEVICE_ATTR(capability, 0444, disk_capability_show, NULL);
1183 static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
1184 static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
1185 static DEVICE_ATTR(badblocks, 0644, disk_badblocks_show, disk_badblocks_store);
1186 #ifdef CONFIG_FAIL_MAKE_REQUEST
1187 static struct device_attribute dev_attr_fail =
1188         __ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
1189 #endif
1190 #ifdef CONFIG_FAIL_IO_TIMEOUT
1191 static struct device_attribute dev_attr_fail_timeout =
1192         __ATTR(io-timeout-fail, 0644, part_timeout_show, part_timeout_store);
1193 #endif
1194 
1195 static struct attribute *disk_attrs[] = {
1196         &dev_attr_range.attr,
1197         &dev_attr_ext_range.attr,
1198         &dev_attr_removable.attr,
1199         &dev_attr_hidden.attr,
1200         &dev_attr_ro.attr,
1201         &dev_attr_size.attr,
1202         &dev_attr_alignment_offset.attr,
1203         &dev_attr_discard_alignment.attr,
1204         &dev_attr_capability.attr,
1205         &dev_attr_stat.attr,
1206         &dev_attr_inflight.attr,
1207         &dev_attr_badblocks.attr,
1208 #ifdef CONFIG_FAIL_MAKE_REQUEST
1209         &dev_attr_fail.attr,
1210 #endif
1211 #ifdef CONFIG_FAIL_IO_TIMEOUT
1212         &dev_attr_fail_timeout.attr,
1213 #endif
1214         NULL
1215 };
1216 
1217 static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)
1218 {
1219         struct device *dev = container_of(kobj, typeof(*dev), kobj);
1220         struct gendisk *disk = dev_to_disk(dev);
1221 
1222         if (a == &dev_attr_badblocks.attr && !disk->bb)
1223                 return 0;
1224         return a->mode;
1225 }
1226 
1227 static struct attribute_group disk_attr_group = {
1228         .attrs = disk_attrs,
1229         .is_visible = disk_visible,
1230 };
1231 
1232 static const struct attribute_group *disk_attr_groups[] = {
1233         &disk_attr_group,
1234         NULL
1235 };
1236 
1237 /**
1238  * disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
1239  * @disk: disk to replace part_tbl for
1240  * @new_ptbl: new part_tbl to install
1241  *
1242  * Replace disk->part_tbl with @new_ptbl in RCU-safe way.  The
1243  * original ptbl is freed using RCU callback.
1244  *
1245  * LOCKING:
1246  * Matching bd_mutex locked or the caller is the only user of @disk.
1247  */
1248 static void disk_replace_part_tbl(struct gendisk *disk,
1249                                   struct disk_part_tbl *new_ptbl)
1250 {
1251         struct disk_part_tbl *old_ptbl =
1252                 rcu_dereference_protected(disk->part_tbl, 1);
1253 
1254         rcu_assign_pointer(disk->part_tbl, new_ptbl);
1255 
1256         if (old_ptbl) {
1257                 rcu_assign_pointer(old_ptbl->last_lookup, NULL);
1258                 kfree_rcu(old_ptbl, rcu_head);
1259         }
1260 }
1261 
1262 /**
1263  * disk_expand_part_tbl - expand disk->part_tbl
1264  * @disk: disk to expand part_tbl for
1265  * @partno: expand such that this partno can fit in
1266  *
1267  * Expand disk->part_tbl such that @partno can fit in.  disk->part_tbl
1268  * uses RCU to allow unlocked dereferencing for stats and other stuff.
1269  *
1270  * LOCKING:
1271  * Matching bd_mutex locked or the caller is the only user of @disk.
1272  * Might sleep.
1273  *
1274  * RETURNS:
1275  * 0 on success, -errno on failure.
1276  */
1277 int disk_expand_part_tbl(struct gendisk *disk, int partno)
1278 {
1279         struct disk_part_tbl *old_ptbl =
1280                 rcu_dereference_protected(disk->part_tbl, 1);
1281         struct disk_part_tbl *new_ptbl;
1282         int len = old_ptbl ? old_ptbl->len : 0;
1283         int i, target;
1284 
1285         /*
1286          * check for int overflow, since we can get here from blkpg_ioctl()
1287          * with a user passed 'partno'.
1288          */
1289         target = partno + 1;
1290         if (target < 0)
1291                 return -EINVAL;
1292 
1293         /* disk_max_parts() is zero during initialization, ignore if so */
1294         if (disk_max_parts(disk) && target > disk_max_parts(disk))
1295                 return -EINVAL;
1296 
1297         if (target <= len)
1298                 return 0;
1299 
1300         new_ptbl = kzalloc_node(struct_size(new_ptbl, part, target), GFP_KERNEL,
1301                                 disk->node_id);
1302         if (!new_ptbl)
1303                 return -ENOMEM;
1304 
1305         new_ptbl->len = target;
1306 
1307         for (i = 0; i < len; i++)
1308                 rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
1309 
1310         disk_replace_part_tbl(disk, new_ptbl);
1311         return 0;
1312 }
1313 
1314 static void disk_release(struct device *dev)
1315 {
1316         struct gendisk *disk = dev_to_disk(dev);
1317 
1318         blk_free_devt(dev->devt);
1319         disk_release_events(disk);
1320         kfree(disk->random);
1321         disk_replace_part_tbl(disk, NULL);
1322         hd_free_part(&disk->part0);
1323         if (disk->queue)
1324                 blk_put_queue(disk->queue);
1325         kfree(disk);
1326 }
1327 struct class block_class = {
1328         .name           = "block",
1329 };
1330 
1331 static char *block_devnode(struct device *dev, umode_t *mode,
1332                            kuid_t *uid, kgid_t *gid)
1333 {
1334         struct gendisk *disk = dev_to_disk(dev);
1335 
1336         if (disk->devnode)
1337                 return disk->devnode(disk, mode);
1338         return NULL;
1339 }
1340 
1341 static const struct device_type disk_type = {
1342         .name           = "disk",
1343         .groups         = disk_attr_groups,
1344         .release        = disk_release,
1345         .devnode        = block_devnode,
1346 };
1347 
1348 #ifdef CONFIG_PROC_FS
1349 /*
1350  * aggregate disk stat collector.  Uses the same stats that the sysfs
1351  * entries do, above, but makes them available through one seq_file.
1352  *
1353  * The output looks suspiciously like /proc/partitions with a bunch of
1354  * extra fields.
1355  */
1356 static int diskstats_show(struct seq_file *seqf, void *v)
1357 {
1358         struct gendisk *gp = v;
1359         struct disk_part_iter piter;
1360         struct hd_struct *hd;
1361         char buf[BDEVNAME_SIZE];
1362         unsigned int inflight;
1363 
1364         /*
1365         if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
1366                 seq_puts(seqf,  "major minor name"
1367                                 "     rio rmerge rsect ruse wio wmerge "
1368                                 "wsect wuse running use aveq"
1369                                 "\n\n");
1370         */
1371 
1372         disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
1373         while ((hd = disk_part_iter_next(&piter))) {
1374                 inflight = part_in_flight(gp->queue, hd);
1375                 seq_printf(seqf, "%4d %7d %s "
1376                            "%lu %lu %lu %u "
1377                            "%lu %lu %lu %u "
1378                            "%u %u %u "
1379                            "%lu %lu %lu %u\n",
1380                            MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
1381                            disk_name(gp, hd->partno, buf),
1382                            part_stat_read(hd, ios[STAT_READ]),
1383                            part_stat_read(hd, merges[STAT_READ]),
1384                            part_stat_read(hd, sectors[STAT_READ]),
1385                            (unsigned int)part_stat_read_msecs(hd, STAT_READ),
1386                            part_stat_read(hd, ios[STAT_WRITE]),
1387                            part_stat_read(hd, merges[STAT_WRITE]),
1388                            part_stat_read(hd, sectors[STAT_WRITE]),
1389                            (unsigned int)part_stat_read_msecs(hd, STAT_WRITE),
1390                            inflight,
1391                            jiffies_to_msecs(part_stat_read(hd, io_ticks)),
1392                            jiffies_to_msecs(part_stat_read(hd, time_in_queue)),
1393                            part_stat_read(hd, ios[STAT_DISCARD]),
1394                            part_stat_read(hd, merges[STAT_DISCARD]),
1395                            part_stat_read(hd, sectors[STAT_DISCARD]),
1396                            (unsigned int)part_stat_read_msecs(hd, STAT_DISCARD)
1397                         );
1398         }
1399         disk_part_iter_exit(&piter);
1400 
1401         return 0;
1402 }
1403 
1404 static const struct seq_operations diskstats_op = {
1405         .start  = disk_seqf_start,
1406         .next   = disk_seqf_next,
1407         .stop   = disk_seqf_stop,
1408         .show   = diskstats_show
1409 };
1410 
1411 static int __init proc_genhd_init(void)
1412 {
1413         proc_create_seq("diskstats", 0, NULL, &diskstats_op);
1414         proc_create_seq("partitions", 0, NULL, &partitions_op);
1415         return 0;
1416 }
1417 module_init(proc_genhd_init);
1418 #endif /* CONFIG_PROC_FS */
1419 
1420 dev_t blk_lookup_devt(const char *name, int partno)
1421 {
1422         dev_t devt = MKDEV(0, 0);
1423         struct class_dev_iter iter;
1424         struct device *dev;
1425 
1426         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
1427         while ((dev = class_dev_iter_next(&iter))) {
1428                 struct gendisk *disk = dev_to_disk(dev);
1429                 struct hd_struct *part;
1430 
1431                 if (strcmp(dev_name(dev), name))
1432                         continue;
1433 
1434                 if (partno < disk->minors) {
1435                         /* We need to return the right devno, even
1436                          * if the partition doesn't exist yet.
1437                          */
1438                         devt = MKDEV(MAJOR(dev->devt),
1439                                      MINOR(dev->devt) + partno);
1440                         break;
1441                 }
1442                 part = disk_get_part(disk, partno);
1443                 if (part) {
1444                         devt = part_devt(part);
1445                         disk_put_part(part);
1446                         break;
1447                 }
1448                 disk_put_part(part);
1449         }
1450         class_dev_iter_exit(&iter);
1451         return devt;
1452 }
1453 EXPORT_SYMBOL(blk_lookup_devt);
1454 
1455 struct gendisk *__alloc_disk_node(int minors, int node_id)
1456 {
1457         struct gendisk *disk;
1458         struct disk_part_tbl *ptbl;
1459 
1460         if (minors > DISK_MAX_PARTS) {
1461                 printk(KERN_ERR
1462                         "block: can't allocate more than %d partitions\n",
1463                         DISK_MAX_PARTS);
1464                 minors = DISK_MAX_PARTS;
1465         }
1466 
1467         disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
1468         if (disk) {
1469                 if (!init_part_stats(&disk->part0)) {
1470                         kfree(disk);
1471                         return NULL;
1472                 }
1473                 init_rwsem(&disk->lookup_sem);
1474                 disk->node_id = node_id;
1475                 if (disk_expand_part_tbl(disk, 0)) {
1476                         free_part_stats(&disk->part0);
1477                         kfree(disk);
1478                         return NULL;
1479                 }
1480                 ptbl = rcu_dereference_protected(disk->part_tbl, 1);
1481                 rcu_assign_pointer(ptbl->part[0], &disk->part0);
1482 
1483                 /*
1484                  * set_capacity() and get_capacity() currently don't use
1485                  * seqcounter to read/update the part0->nr_sects. Still init
1486                  * the counter as we can read the sectors in IO submission
1487                  * patch using seqence counters.
1488                  *
1489                  * TODO: Ideally set_capacity() and get_capacity() should be
1490                  * converted to make use of bd_mutex and sequence counters.
1491                  */
1492                 seqcount_init(&disk->part0.nr_sects_seq);
1493                 if (hd_ref_init(&disk->part0)) {
1494                         hd_free_part(&disk->part0);
1495                         kfree(disk);
1496                         return NULL;
1497                 }
1498 
1499                 disk->minors = minors;
1500                 rand_initialize_disk(disk);
1501                 disk_to_dev(disk)->class = &block_class;
1502                 disk_to_dev(disk)->type = &disk_type;
1503                 device_initialize(disk_to_dev(disk));
1504         }
1505         return disk;
1506 }
1507 EXPORT_SYMBOL(__alloc_disk_node);
1508 
1509 struct kobject *get_disk_and_module(struct gendisk *disk)
1510 {
1511         struct module *owner;
1512         struct kobject *kobj;
1513 
1514         if (!disk->fops)
1515                 return NULL;
1516         owner = disk->fops->owner;
1517         if (owner && !try_module_get(owner))
1518                 return NULL;
1519         kobj = kobject_get_unless_zero(&disk_to_dev(disk)->kobj);
1520         if (kobj == NULL) {
1521                 module_put(owner);
1522                 return NULL;
1523         }
1524         return kobj;
1525 
1526 }
1527 EXPORT_SYMBOL(get_disk_and_module);
1528 
1529 void put_disk(struct gendisk *disk)
1530 {
1531         if (disk)
1532                 kobject_put(&disk_to_dev(disk)->kobj);
1533 }
1534 EXPORT_SYMBOL(put_disk);
1535 
1536 /*
1537  * This is a counterpart of get_disk_and_module() and thus also of
1538  * get_gendisk().
1539  */
1540 void put_disk_and_module(struct gendisk *disk)
1541 {
1542         if (disk) {
1543                 struct module *owner = disk->fops->owner;
1544 
1545                 put_disk(disk);
1546                 module_put(owner);
1547         }
1548 }
1549 EXPORT_SYMBOL(put_disk_and_module);
1550 
1551 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
1552 {
1553         char event[] = "DISK_RO=1";
1554         char *envp[] = { event, NULL };
1555 
1556         if (!ro)
1557                 event[8] = '';
1558         kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
1559 }
1560 
1561 void set_device_ro(struct block_device *bdev, int flag)
1562 {
1563         bdev->bd_part->policy = flag;
1564 }
1565 
1566 EXPORT_SYMBOL(set_device_ro);
1567 
1568 void set_disk_ro(struct gendisk *disk, int flag)
1569 {
1570         struct disk_part_iter piter;
1571         struct hd_struct *part;
1572 
1573         if (disk->part0.policy != flag) {
1574                 set_disk_ro_uevent(disk, flag);
1575                 disk->part0.policy = flag;
1576         }
1577 
1578         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
1579         while ((part = disk_part_iter_next(&piter)))
1580                 part->policy = flag;
1581         disk_part_iter_exit(&piter);
1582 }
1583 
1584 EXPORT_SYMBOL(set_disk_ro);
1585 
1586 int bdev_read_only(struct block_device *bdev)
1587 {
1588         if (!bdev)
1589                 return 0;
1590         return bdev->bd_part->policy;
1591 }
1592 
1593 EXPORT_SYMBOL(bdev_read_only);
1594 
1595 int invalidate_partition(struct gendisk *disk, int partno)
1596 {
1597         int res = 0;
1598         struct block_device *bdev = bdget_disk(disk, partno);
1599         if (bdev) {
1600                 fsync_bdev(bdev);
1601                 res = __invalidate_device(bdev, true);
1602                 bdput(bdev);
1603         }
1604         return res;
1605 }
1606 
1607 EXPORT_SYMBOL(invalidate_partition);
1608 
1609 /*
1610  * Disk events - monitor disk events like media change and eject request.
1611  */
1612 struct disk_events {
1613         struct list_head        node;           /* all disk_event's */
1614         struct gendisk          *disk;          /* the associated disk */
1615         spinlock_t              lock;
1616 
1617         struct mutex            block_mutex;    /* protects blocking */
1618         int                     block;          /* event blocking depth */
1619         unsigned int            pending;        /* events already sent out */
1620         unsigned int            clearing;       /* events being cleared */
1621 
1622         long                    poll_msecs;     /* interval, -1 for default */
1623         struct delayed_work     dwork;
1624 };
1625 
1626 static const char *disk_events_strs[] = {
1627         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "media_change",
1628         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "eject_request",
1629 };
1630 
1631 static char *disk_uevents[] = {
1632         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "DISK_MEDIA_CHANGE=1",
1633         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "DISK_EJECT_REQUEST=1",
1634 };
1635 
1636 /* list of all disk_events */
1637 static DEFINE_MUTEX(disk_events_mutex);
1638 static LIST_HEAD(disk_events);
1639 
1640 /* disable in-kernel polling by default */
1641 static unsigned long disk_events_dfl_poll_msecs;
1642 
1643 static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
1644 {
1645         struct disk_events *ev = disk->ev;
1646         long intv_msecs = 0;
1647 
1648         /*
1649          * If device-specific poll interval is set, always use it.  If
1650          * the default is being used, poll if the POLL flag is set.
1651          */
1652         if (ev->poll_msecs >= 0)
1653                 intv_msecs = ev->poll_msecs;
1654         else if (disk->event_flags & DISK_EVENT_FLAG_POLL)
1655                 intv_msecs = disk_events_dfl_poll_msecs;
1656 
1657         return msecs_to_jiffies(intv_msecs);
1658 }
1659 
1660 /**
1661  * disk_block_events - block and flush disk event checking
1662  * @disk: disk to block events for
1663  *
1664  * On return from this function, it is guaranteed that event checking
1665  * isn't in progress and won't happen until unblocked by
1666  * disk_unblock_events().  Events blocking is counted and the actual
1667  * unblocking happens after the matching number of unblocks are done.
1668  *
1669  * Note that this intentionally does not block event checking from
1670  * disk_clear_events().
1671  *
1672  * CONTEXT:
1673  * Might sleep.
1674  */
1675 void disk_block_events(struct gendisk *disk)
1676 {
1677         struct disk_events *ev = disk->ev;
1678         unsigned long flags;
1679         bool cancel;
1680 
1681         if (!ev)
1682                 return;
1683 
1684         /*
1685          * Outer mutex ensures that the first blocker completes canceling
1686          * the event work before further blockers are allowed to finish.
1687          */
1688         mutex_lock(&ev->block_mutex);
1689 
1690         spin_lock_irqsave(&ev->lock, flags);
1691         cancel = !ev->block++;
1692         spin_unlock_irqrestore(&ev->lock, flags);
1693 
1694         if (cancel)
1695                 cancel_delayed_work_sync(&disk->ev->dwork);
1696 
1697         mutex_unlock(&ev->block_mutex);
1698 }
1699 
1700 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
1701 {
1702         struct disk_events *ev = disk->ev;
1703         unsigned long intv;
1704         unsigned long flags;
1705 
1706         spin_lock_irqsave(&ev->lock, flags);
1707 
1708         if (WARN_ON_ONCE(ev->block <= 0))
1709                 goto out_unlock;
1710 
1711         if (--ev->block)
1712                 goto out_unlock;
1713 
1714         intv = disk_events_poll_jiffies(disk);
1715         if (check_now)
1716                 queue_delayed_work(system_freezable_power_efficient_wq,
1717                                 &ev->dwork, 0);
1718         else if (intv)
1719                 queue_delayed_work(system_freezable_power_efficient_wq,
1720                                 &ev->dwork, intv);
1721 out_unlock:
1722         spin_unlock_irqrestore(&ev->lock, flags);
1723 }
1724 
1725 /**
1726  * disk_unblock_events - unblock disk event checking
1727  * @disk: disk to unblock events for
1728  *
1729  * Undo disk_block_events().  When the block count reaches zero, it
1730  * starts events polling if configured.
1731  *
1732  * CONTEXT:
1733  * Don't care.  Safe to call from irq context.
1734  */
1735 void disk_unblock_events(struct gendisk *disk)
1736 {
1737         if (disk->ev)
1738                 __disk_unblock_events(disk, false);
1739 }
1740 
1741 /**
1742  * disk_flush_events - schedule immediate event checking and flushing
1743  * @disk: disk to check and flush events for
1744  * @mask: events to flush
1745  *
1746  * Schedule immediate event checking on @disk if not blocked.  Events in
1747  * @mask are scheduled to be cleared from the driver.  Note that this
1748  * doesn't clear the events from @disk->ev.
1749  *
1750  * CONTEXT:
1751  * If @mask is non-zero must be called with bdev->bd_mutex held.
1752  */
1753 void disk_flush_events(struct gendisk *disk, unsigned int mask)
1754 {
1755         struct disk_events *ev = disk->ev;
1756 
1757         if (!ev)
1758                 return;
1759 
1760         spin_lock_irq(&ev->lock);
1761         ev->clearing |= mask;
1762         if (!ev->block)
1763                 mod_delayed_work(system_freezable_power_efficient_wq,
1764                                 &ev->dwork, 0);
1765         spin_unlock_irq(&ev->lock);
1766 }
1767 
1768 /**
1769  * disk_clear_events - synchronously check, clear and return pending events
1770  * @disk: disk to fetch and clear events from
1771  * @mask: mask of events to be fetched and cleared
1772  *
1773  * Disk events are synchronously checked and pending events in @mask
1774  * are cleared and returned.  This ignores the block count.
1775  *
1776  * CONTEXT:
1777  * Might sleep.
1778  */
1779 unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
1780 {
1781         const struct block_device_operations *bdops = disk->fops;
1782         struct disk_events *ev = disk->ev;
1783         unsigned int pending;
1784         unsigned int clearing = mask;
1785 
1786         if (!ev) {
1787                 /* for drivers still using the old ->media_changed method */
1788                 if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
1789                     bdops->media_changed && bdops->media_changed(disk))
1790                         return DISK_EVENT_MEDIA_CHANGE;
1791                 return 0;
1792         }
1793 
1794         disk_block_events(disk);
1795 
1796         /*
1797          * store the union of mask and ev->clearing on the stack so that the
1798          * race with disk_flush_events does not cause ambiguity (ev->clearing
1799          * can still be modified even if events are blocked).
1800          */
1801         spin_lock_irq(&ev->lock);
1802         clearing |= ev->clearing;
1803         ev->clearing = 0;
1804         spin_unlock_irq(&ev->lock);
1805 
1806         disk_check_events(ev, &clearing);
1807         /*
1808          * if ev->clearing is not 0, the disk_flush_events got called in the
1809          * middle of this function, so we want to run the workfn without delay.
1810          */
1811         __disk_unblock_events(disk, ev->clearing ? true : false);
1812 
1813         /* then, fetch and clear pending events */
1814         spin_lock_irq(&ev->lock);
1815         pending = ev->pending & mask;
1816         ev->pending &= ~mask;
1817         spin_unlock_irq(&ev->lock);
1818         WARN_ON_ONCE(clearing & mask);
1819 
1820         return pending;
1821 }
1822 
1823 /*
1824  * Separate this part out so that a different pointer for clearing_ptr can be
1825  * passed in for disk_clear_events.
1826  */
1827 static void disk_events_workfn(struct work_struct *work)
1828 {
1829         struct delayed_work *dwork = to_delayed_work(work);
1830         struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
1831 
1832         disk_check_events(ev, &ev->clearing);
1833 }
1834 
1835 static void disk_check_events(struct disk_events *ev,
1836                               unsigned int *clearing_ptr)
1837 {
1838         struct gendisk *disk = ev->disk;
1839         char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
1840         unsigned int clearing = *clearing_ptr;
1841         unsigned int events;
1842         unsigned long intv;
1843         int nr_events = 0, i;
1844 
1845         /* check events */
1846         events = disk->fops->check_events(disk, clearing);
1847 
1848         /* accumulate pending events and schedule next poll if necessary */
1849         spin_lock_irq(&ev->lock);
1850 
1851         events &= ~ev->pending;
1852         ev->pending |= events;
1853         *clearing_ptr &= ~clearing;
1854 
1855         intv = disk_events_poll_jiffies(disk);
1856         if (!ev->block && intv)
1857                 queue_delayed_work(system_freezable_power_efficient_wq,
1858                                 &ev->dwork, intv);
1859 
1860         spin_unlock_irq(&ev->lock);
1861 
1862         /*
1863          * Tell userland about new events.  Only the events listed in
1864          * @disk->events are reported, and only if DISK_EVENT_FLAG_UEVENT
1865          * is set. Otherwise, events are processed internally but never
1866          * get reported to userland.
1867          */
1868         for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
1869                 if ((events & disk->events & (1 << i)) &&
1870                     (disk->event_flags & DISK_EVENT_FLAG_UEVENT))
1871                         envp[nr_events++] = disk_uevents[i];
1872 
1873         if (nr_events)
1874                 kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
1875 }
1876 
1877 /*
1878  * A disk events enabled device has the following sysfs nodes under
1879  * its /sys/block/X/ directory.
1880  *
1881  * events               : list of all supported events
1882  * events_async         : list of events which can be detected w/o polling
1883  *                        (always empty, only for backwards compatibility)
1884  * events_poll_msecs    : polling interval, 0: disable, -1: system default
1885  */
1886 static ssize_t __disk_events_show(unsigned int events, char *buf)
1887 {
1888         const char *delim = "";
1889         ssize_t pos = 0;
1890         int i;
1891 
1892         for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
1893                 if (events & (1 << i)) {
1894                         pos += sprintf(buf + pos, "%s%s",
1895                                        delim, disk_events_strs[i]);
1896                         delim = " ";
1897                 }
1898         if (pos)
1899                 pos += sprintf(buf + pos, "\n");
1900         return pos;
1901 }
1902 
1903 static ssize_t disk_events_show(struct device *dev,
1904                                 struct device_attribute *attr, char *buf)
1905 {
1906         struct gendisk *disk = dev_to_disk(dev);
1907 
1908         if (!(disk->event_flags & DISK_EVENT_FLAG_UEVENT))
1909                 return 0;
1910 
1911         return __disk_events_show(disk->events, buf);
1912 }
1913 
1914 static ssize_t disk_events_async_show(struct device *dev,
1915                                       struct device_attribute *attr, char *buf)
1916 {
1917         return 0;
1918 }
1919 
1920 static ssize_t disk_events_poll_msecs_show(struct device *dev,
1921                                            struct device_attribute *attr,
1922                                            char *buf)
1923 {
1924         struct gendisk *disk = dev_to_disk(dev);
1925 
1926         if (!disk->ev)
1927                 return sprintf(buf, "-1\n");
1928 
1929         return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
1930 }
1931 
1932 static ssize_t disk_events_poll_msecs_store(struct device *dev,
1933                                             struct device_attribute *attr,
1934                                             const char *buf, size_t count)
1935 {
1936         struct gendisk *disk = dev_to_disk(dev);
1937         long intv;
1938 
1939         if (!count || !sscanf(buf, "%ld", &intv))
1940                 return -EINVAL;
1941 
1942         if (intv < 0 && intv != -1)
1943                 return -EINVAL;
1944 
1945         if (!disk->ev)
1946                 return -ENODEV;
1947 
1948         disk_block_events(disk);
1949         disk->ev->poll_msecs = intv;
1950         __disk_unblock_events(disk, true);
1951 
1952         return count;
1953 }
1954 
1955 static const DEVICE_ATTR(events, 0444, disk_events_show, NULL);
1956 static const DEVICE_ATTR(events_async, 0444, disk_events_async_show, NULL);
1957 static const DEVICE_ATTR(events_poll_msecs, 0644,
1958                          disk_events_poll_msecs_show,
1959                          disk_events_poll_msecs_store);
1960 
1961 static const struct attribute *disk_events_attrs[] = {
1962         &dev_attr_events.attr,
1963         &dev_attr_events_async.attr,
1964         &dev_attr_events_poll_msecs.attr,
1965         NULL,
1966 };
1967 
1968 /*
1969  * The default polling interval can be specified by the kernel
1970  * parameter block.events_dfl_poll_msecs which defaults to 0
1971  * (disable).  This can also be modified runtime by writing to
1972  * /sys/module/block/parameters/events_dfl_poll_msecs.
1973  */
1974 static int disk_events_set_dfl_poll_msecs(const char *val,
1975                                           const struct kernel_param *kp)
1976 {
1977         struct disk_events *ev;
1978         int ret;
1979 
1980         ret = param_set_ulong(val, kp);
1981         if (ret < 0)
1982                 return ret;
1983 
1984         mutex_lock(&disk_events_mutex);
1985 
1986         list_for_each_entry(ev, &disk_events, node)
1987                 disk_flush_events(ev->disk, 0);
1988 
1989         mutex_unlock(&disk_events_mutex);
1990 
1991         return 0;
1992 }
1993 
1994 static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
1995         .set    = disk_events_set_dfl_poll_msecs,
1996         .get    = param_get_ulong,
1997 };
1998 
1999 #undef MODULE_PARAM_PREFIX
2000 #define MODULE_PARAM_PREFIX     "block."
2001 
2002 module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
2003                 &disk_events_dfl_poll_msecs, 0644);
2004 
2005 /*
2006  * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
2007  */
2008 static void disk_alloc_events(struct gendisk *disk)
2009 {
2010         struct disk_events *ev;
2011 
2012         if (!disk->fops->check_events || !disk->events)
2013                 return;
2014 
2015         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
2016         if (!ev) {
2017                 pr_warn("%s: failed to initialize events\n", disk->disk_name);
2018                 return;
2019         }
2020 
2021         INIT_LIST_HEAD(&ev->node);
2022         ev->disk = disk;
2023         spin_lock_init(&ev->lock);
2024         mutex_init(&ev->block_mutex);
2025         ev->block = 1;
2026         ev->poll_msecs = -1;
2027         INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
2028 
2029         disk->ev = ev;
2030 }
2031 
2032 static void disk_add_events(struct gendisk *disk)
2033 {
2034         /* FIXME: error handling */
2035         if (sysfs_create_files(&disk_to_dev(disk)->kobj, disk_events_attrs) < 0)
2036                 pr_warn("%s: failed to create sysfs files for events\n",
2037                         disk->disk_name);
2038 
2039         if (!disk->ev)
2040                 return;
2041 
2042         mutex_lock(&disk_events_mutex);
2043         list_add_tail(&disk->ev->node, &disk_events);
2044         mutex_unlock(&disk_events_mutex);
2045 
2046         /*
2047          * Block count is initialized to 1 and the following initial
2048          * unblock kicks it into action.
2049          */
2050         __disk_unblock_events(disk, true);
2051 }
2052 
2053 static void disk_del_events(struct gendisk *disk)
2054 {
2055         if (disk->ev) {
2056                 disk_block_events(disk);
2057 
2058                 mutex_lock(&disk_events_mutex);
2059                 list_del_init(&disk->ev->node);
2060                 mutex_unlock(&disk_events_mutex);
2061         }
2062 
2063         sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
2064 }
2065 
2066 static void disk_release_events(struct gendisk *disk)
2067 {
2068         /* the block count should be 1 from disk_del_events() */
2069         WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
2070         kfree(disk->ev);
2071 }
2072 

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