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TOMOYO Linux Cross Reference
Linux/block/genhd.c

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

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