Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/block/genhd.c

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

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