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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/init.h>
 12 #include <linux/spinlock.h>
 13 #include <linux/proc_fs.h>
 14 #include <linux/seq_file.h>
 15 #include <linux/slab.h>
 16 #include <linux/kmod.h>
 17 #include <linux/kobj_map.h>
 18 #include <linux/mutex.h>
 19 #include <linux/idr.h>
 20 #include <linux/log2.h>
 21 #include <linux/pm_runtime.h>
 22 
 23 #include "blk.h"
 24 
 25 static DEFINE_MUTEX(block_class_lock);
 26 struct kobject *block_depr;
 27 
 28 /* for extended dynamic devt allocation, currently only one major is used */
 29 #define NR_EXT_DEVT             (1 << MINORBITS)
 30 
 31 /* For extended devt allocation.  ext_devt_lock prevents look up
 32  * results from going away underneath its user.
 33  */
 34 static DEFINE_SPINLOCK(ext_devt_lock);
 35 static DEFINE_IDR(ext_devt_idr);
 36 
 37 static struct device_type disk_type;
 38 
 39 static void disk_check_events(struct disk_events *ev,
 40                               unsigned int *clearing_ptr);
 41 static void disk_alloc_events(struct gendisk *disk);
 42 static void disk_add_events(struct gendisk *disk);
 43 static void disk_del_events(struct gendisk *disk);
 44 static void disk_release_events(struct gendisk *disk);
 45 
 46 /**
 47  * disk_get_part - get partition
 48  * @disk: disk to look partition from
 49  * @partno: partition number
 50  *
 51  * Look for partition @partno from @disk.  If found, increment
 52  * reference count and return it.
 53  *
 54  * CONTEXT:
 55  * Don't care.
 56  *
 57  * RETURNS:
 58  * Pointer to the found partition on success, NULL if not found.
 59  */
 60 struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
 61 {
 62         struct hd_struct *part = NULL;
 63         struct disk_part_tbl *ptbl;
 64 
 65         if (unlikely(partno < 0))
 66                 return NULL;
 67 
 68         rcu_read_lock();
 69 
 70         ptbl = rcu_dereference(disk->part_tbl);
 71         if (likely(partno < ptbl->len)) {
 72                 part = rcu_dereference(ptbl->part[partno]);
 73                 if (part)
 74                         get_device(part_to_dev(part));
 75         }
 76 
 77         rcu_read_unlock();
 78 
 79         return part;
 80 }
 81 EXPORT_SYMBOL_GPL(disk_get_part);
 82 
 83 /**
 84  * disk_part_iter_init - initialize partition iterator
 85  * @piter: iterator to initialize
 86  * @disk: disk to iterate over
 87  * @flags: DISK_PITER_* flags
 88  *
 89  * Initialize @piter so that it iterates over partitions of @disk.
 90  *
 91  * CONTEXT:
 92  * Don't care.
 93  */
 94 void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 95                           unsigned int flags)
 96 {
 97         struct disk_part_tbl *ptbl;
 98 
 99         rcu_read_lock();
100         ptbl = rcu_dereference(disk->part_tbl);
101 
102         piter->disk = disk;
103         piter->part = NULL;
104 
105         if (flags & DISK_PITER_REVERSE)
106                 piter->idx = ptbl->len - 1;
107         else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
108                 piter->idx = 0;
109         else
110                 piter->idx = 1;
111 
112         piter->flags = flags;
113 
114         rcu_read_unlock();
115 }
116 EXPORT_SYMBOL_GPL(disk_part_iter_init);
117 
118 /**
119  * disk_part_iter_next - proceed iterator to the next partition and return it
120  * @piter: iterator of interest
121  *
122  * Proceed @piter to the next partition and return it.
123  *
124  * CONTEXT:
125  * Don't care.
126  */
127 struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
128 {
129         struct disk_part_tbl *ptbl;
130         int inc, end;
131 
132         /* put the last partition */
133         disk_put_part(piter->part);
134         piter->part = NULL;
135 
136         /* get part_tbl */
137         rcu_read_lock();
138         ptbl = rcu_dereference(piter->disk->part_tbl);
139 
140         /* determine iteration parameters */
141         if (piter->flags & DISK_PITER_REVERSE) {
142                 inc = -1;
143                 if (piter->flags & (DISK_PITER_INCL_PART0 |
144                                     DISK_PITER_INCL_EMPTY_PART0))
145                         end = -1;
146                 else
147                         end = 0;
148         } else {
149                 inc = 1;
150                 end = ptbl->len;
151         }
152 
153         /* iterate to the next partition */
154         for (; piter->idx != end; piter->idx += inc) {
155                 struct hd_struct *part;
156 
157                 part = rcu_dereference(ptbl->part[piter->idx]);
158                 if (!part)
159                         continue;
160                 if (!part_nr_sects_read(part) &&
161                     !(piter->flags & DISK_PITER_INCL_EMPTY) &&
162                     !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
163                       piter->idx == 0))
164                         continue;
165 
166                 get_device(part_to_dev(part));
167                 piter->part = part;
168                 piter->idx += inc;
169                 break;
170         }
171 
172         rcu_read_unlock();
173 
174         return piter->part;
175 }
176 EXPORT_SYMBOL_GPL(disk_part_iter_next);
177 
178 /**
179  * disk_part_iter_exit - finish up partition iteration
180  * @piter: iter of interest
181  *
182  * Called when iteration is over.  Cleans up @piter.
183  *
184  * CONTEXT:
185  * Don't care.
186  */
187 void disk_part_iter_exit(struct disk_part_iter *piter)
188 {
189         disk_put_part(piter->part);
190         piter->part = NULL;
191 }
192 EXPORT_SYMBOL_GPL(disk_part_iter_exit);
193 
194 static inline int sector_in_part(struct hd_struct *part, sector_t sector)
195 {
196         return part->start_sect <= sector &&
197                 sector < part->start_sect + part_nr_sects_read(part);
198 }
199 
200 /**
201  * disk_map_sector_rcu - map sector to partition
202  * @disk: gendisk of interest
203  * @sector: sector to map
204  *
205  * Find out which partition @sector maps to on @disk.  This is
206  * primarily used for stats accounting.
207  *
208  * CONTEXT:
209  * RCU read locked.  The returned partition pointer is valid only
210  * while preemption is disabled.
211  *
212  * RETURNS:
213  * Found partition on success, part0 is returned if no partition matches
214  */
215 struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
216 {
217         struct disk_part_tbl *ptbl;
218         struct hd_struct *part;
219         int i;
220 
221         ptbl = rcu_dereference(disk->part_tbl);
222 
223         part = rcu_dereference(ptbl->last_lookup);
224         if (part && sector_in_part(part, sector))
225                 return part;
226 
227         for (i = 1; i < ptbl->len; i++) {
228                 part = rcu_dereference(ptbl->part[i]);
229 
230                 if (part && sector_in_part(part, sector)) {
231                         rcu_assign_pointer(ptbl->last_lookup, part);
232                         return part;
233                 }
234         }
235         return &disk->part0;
236 }
237 EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
238 
239 /*
240  * Can be deleted altogether. Later.
241  *
242  */
243 static struct blk_major_name {
244         struct blk_major_name *next;
245         int major;
246         char name[16];
247 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
248 
249 /* index in the above - for now: assume no multimajor ranges */
250 static inline int major_to_index(unsigned major)
251 {
252         return major % BLKDEV_MAJOR_HASH_SIZE;
253 }
254 
255 #ifdef CONFIG_PROC_FS
256 void blkdev_show(struct seq_file *seqf, off_t offset)
257 {
258         struct blk_major_name *dp;
259 
260         if (offset < BLKDEV_MAJOR_HASH_SIZE) {
261                 mutex_lock(&block_class_lock);
262                 for (dp = major_names[offset]; dp; dp = dp->next)
263                         seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
264                 mutex_unlock(&block_class_lock);
265         }
266 }
267 #endif /* CONFIG_PROC_FS */
268 
269 /**
270  * register_blkdev - register a new block device
271  *
272  * @major: the requested major device number [1..255]. If @major=0, try to
273  *         allocate any unused major number.
274  * @name: the name of the new block device as a zero terminated string
275  *
276  * The @name must be unique within the system.
277  *
278  * The return value depends on the @major input parameter.
279  *  - if a major device number was requested in range [1..255] then the
280  *    function returns zero on success, or a negative error code
281  *  - if any unused major number was requested with @major=0 parameter
282  *    then the return value is the allocated major number in range
283  *    [1..255] or a negative error code otherwise
284  */
285 int register_blkdev(unsigned int major, const char *name)
286 {
287         struct blk_major_name **n, *p;
288         int index, ret = 0;
289 
290         mutex_lock(&block_class_lock);
291 
292         /* temporary */
293         if (major == 0) {
294                 for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
295                         if (major_names[index] == NULL)
296                                 break;
297                 }
298 
299                 if (index == 0) {
300                         printk("register_blkdev: failed to get major for %s\n",
301                                name);
302                         ret = -EBUSY;
303                         goto out;
304                 }
305                 major = index;
306                 ret = major;
307         }
308 
309         p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
310         if (p == NULL) {
311                 ret = -ENOMEM;
312                 goto out;
313         }
314 
315         p->major = major;
316         strlcpy(p->name, name, sizeof(p->name));
317         p->next = NULL;
318         index = major_to_index(major);
319 
320         for (n = &major_names[index]; *n; n = &(*n)->next) {
321                 if ((*n)->major == major)
322                         break;
323         }
324         if (!*n)
325                 *n = p;
326         else
327                 ret = -EBUSY;
328 
329         if (ret < 0) {
330                 printk("register_blkdev: cannot get major %d for %s\n",
331                        major, name);
332                 kfree(p);
333         }
334 out:
335         mutex_unlock(&block_class_lock);
336         return ret;
337 }
338 
339 EXPORT_SYMBOL(register_blkdev);
340 
341 void unregister_blkdev(unsigned int major, const char *name)
342 {
343         struct blk_major_name **n;
344         struct blk_major_name *p = NULL;
345         int index = major_to_index(major);
346 
347         mutex_lock(&block_class_lock);
348         for (n = &major_names[index]; *n; n = &(*n)->next)
349                 if ((*n)->major == major)
350                         break;
351         if (!*n || strcmp((*n)->name, name)) {
352                 WARN_ON(1);
353         } else {
354                 p = *n;
355                 *n = p->next;
356         }
357         mutex_unlock(&block_class_lock);
358         kfree(p);
359 }
360 
361 EXPORT_SYMBOL(unregister_blkdev);
362 
363 static struct kobj_map *bdev_map;
364 
365 /**
366  * blk_mangle_minor - scatter minor numbers apart
367  * @minor: minor number to mangle
368  *
369  * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
370  * is enabled.  Mangling twice gives the original value.
371  *
372  * RETURNS:
373  * Mangled value.
374  *
375  * CONTEXT:
376  * Don't care.
377  */
378 static int blk_mangle_minor(int minor)
379 {
380 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
381         int i;
382 
383         for (i = 0; i < MINORBITS / 2; i++) {
384                 int low = minor & (1 << i);
385                 int high = minor & (1 << (MINORBITS - 1 - i));
386                 int distance = MINORBITS - 1 - 2 * i;
387 
388                 minor ^= low | high;    /* clear both bits */
389                 low <<= distance;       /* swap the positions */
390                 high >>= distance;
391                 minor |= low | high;    /* and set */
392         }
393 #endif
394         return minor;
395 }
396 
397 /**
398  * blk_alloc_devt - allocate a dev_t for a partition
399  * @part: partition to allocate dev_t for
400  * @devt: out parameter for resulting dev_t
401  *
402  * Allocate a dev_t for block device.
403  *
404  * RETURNS:
405  * 0 on success, allocated dev_t is returned in *@devt.  -errno on
406  * failure.
407  *
408  * CONTEXT:
409  * Might sleep.
410  */
411 int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
412 {
413         struct gendisk *disk = part_to_disk(part);
414         int idx;
415 
416         /* in consecutive minor range? */
417         if (part->partno < disk->minors) {
418                 *devt = MKDEV(disk->major, disk->first_minor + part->partno);
419                 return 0;
420         }
421 
422         /* allocate ext devt */
423         idr_preload(GFP_KERNEL);
424 
425         spin_lock_bh(&ext_devt_lock);
426         idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);
427         spin_unlock_bh(&ext_devt_lock);
428 
429         idr_preload_end();
430         if (idx < 0)
431                 return idx == -ENOSPC ? -EBUSY : idx;
432 
433         *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
434         return 0;
435 }
436 
437 /**
438  * blk_free_devt - free a dev_t
439  * @devt: dev_t to free
440  *
441  * Free @devt which was allocated using blk_alloc_devt().
442  *
443  * CONTEXT:
444  * Might sleep.
445  */
446 void blk_free_devt(dev_t devt)
447 {
448         if (devt == MKDEV(0, 0))
449                 return;
450 
451         if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
452                 spin_lock_bh(&ext_devt_lock);
453                 idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
454                 spin_unlock_bh(&ext_devt_lock);
455         }
456 }
457 
458 static char *bdevt_str(dev_t devt, char *buf)
459 {
460         if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
461                 char tbuf[BDEVT_SIZE];
462                 snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
463                 snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
464         } else
465                 snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
466 
467         return buf;
468 }
469 
470 /*
471  * Register device numbers dev..(dev+range-1)
472  * range must be nonzero
473  * The hash chain is sorted on range, so that subranges can override.
474  */
475 void blk_register_region(dev_t devt, unsigned long range, struct module *module,
476                          struct kobject *(*probe)(dev_t, int *, void *),
477                          int (*lock)(dev_t, void *), void *data)
478 {
479         kobj_map(bdev_map, devt, range, module, probe, lock, data);
480 }
481 
482 EXPORT_SYMBOL(blk_register_region);
483 
484 void blk_unregister_region(dev_t devt, unsigned long range)
485 {
486         kobj_unmap(bdev_map, devt, range);
487 }
488 
489 EXPORT_SYMBOL(blk_unregister_region);
490 
491 static struct kobject *exact_match(dev_t devt, int *partno, void *data)
492 {
493         struct gendisk *p = data;
494 
495         return &disk_to_dev(p)->kobj;
496 }
497 
498 static int exact_lock(dev_t devt, void *data)
499 {
500         struct gendisk *p = data;
501 
502         if (!get_disk(p))
503                 return -1;
504         return 0;
505 }
506 
507 static void register_disk(struct gendisk *disk)
508 {
509         struct device *ddev = disk_to_dev(disk);
510         struct block_device *bdev;
511         struct disk_part_iter piter;
512         struct hd_struct *part;
513         int err;
514 
515         ddev->parent = disk->driverfs_dev;
516 
517         dev_set_name(ddev, "%s", disk->disk_name);
518 
519         /* delay uevents, until we scanned partition table */
520         dev_set_uevent_suppress(ddev, 1);
521 
522         if (device_add(ddev))
523                 return;
524         if (!sysfs_deprecated) {
525                 err = sysfs_create_link(block_depr, &ddev->kobj,
526                                         kobject_name(&ddev->kobj));
527                 if (err) {
528                         device_del(ddev);
529                         return;
530                 }
531         }
532 
533         /*
534          * avoid probable deadlock caused by allocating memory with
535          * GFP_KERNEL in runtime_resume callback of its all ancestor
536          * devices
537          */
538         pm_runtime_set_memalloc_noio(ddev, true);
539 
540         disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
541         disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
542 
543         /* No minors to use for partitions */
544         if (!disk_part_scan_enabled(disk))
545                 goto exit;
546 
547         /* No such device (e.g., media were just removed) */
548         if (!get_capacity(disk))
549                 goto exit;
550 
551         bdev = bdget_disk(disk, 0);
552         if (!bdev)
553                 goto exit;
554 
555         bdev->bd_invalidated = 1;
556         err = blkdev_get(bdev, FMODE_READ, NULL);
557         if (err < 0)
558                 goto exit;
559         blkdev_put(bdev, FMODE_READ);
560 
561 exit:
562         /* announce disk after possible partitions are created */
563         dev_set_uevent_suppress(ddev, 0);
564         kobject_uevent(&ddev->kobj, KOBJ_ADD);
565 
566         /* announce possible partitions */
567         disk_part_iter_init(&piter, disk, 0);
568         while ((part = disk_part_iter_next(&piter)))
569                 kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
570         disk_part_iter_exit(&piter);
571 }
572 
573 /**
574  * add_disk - add partitioning information to kernel list
575  * @disk: per-device partitioning information
576  *
577  * This function registers the partitioning information in @disk
578  * with the kernel.
579  *
580  * FIXME: error handling
581  */
582 void add_disk(struct gendisk *disk)
583 {
584         struct backing_dev_info *bdi;
585         dev_t devt;
586         int retval;
587 
588         /* minors == 0 indicates to use ext devt from part0 and should
589          * be accompanied with EXT_DEVT flag.  Make sure all
590          * parameters make sense.
591          */
592         WARN_ON(disk->minors && !(disk->major || disk->first_minor));
593         WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
594 
595         disk->flags |= GENHD_FL_UP;
596 
597         retval = blk_alloc_devt(&disk->part0, &devt);
598         if (retval) {
599                 WARN_ON(1);
600                 return;
601         }
602         disk_to_dev(disk)->devt = devt;
603 
604         /* ->major and ->first_minor aren't supposed to be
605          * dereferenced from here on, but set them just in case.
606          */
607         disk->major = MAJOR(devt);
608         disk->first_minor = MINOR(devt);
609 
610         disk_alloc_events(disk);
611 
612         /* Register BDI before referencing it from bdev */
613         bdi = &disk->queue->backing_dev_info;
614         bdi_register_dev(bdi, disk_devt(disk));
615 
616         blk_register_region(disk_devt(disk), disk->minors, NULL,
617                             exact_match, exact_lock, disk);
618         register_disk(disk);
619         blk_register_queue(disk);
620 
621         /*
622          * Take an extra ref on queue which will be put on disk_release()
623          * so that it sticks around as long as @disk is there.
624          */
625         WARN_ON_ONCE(!blk_get_queue(disk->queue));
626 
627         retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
628                                    "bdi");
629         WARN_ON(retval);
630 
631         disk_add_events(disk);
632 }
633 EXPORT_SYMBOL(add_disk);
634 
635 void del_gendisk(struct gendisk *disk)
636 {
637         struct disk_part_iter piter;
638         struct hd_struct *part;
639 
640         disk_del_events(disk);
641 
642         /* invalidate stuff */
643         disk_part_iter_init(&piter, disk,
644                              DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
645         while ((part = disk_part_iter_next(&piter))) {
646                 invalidate_partition(disk, part->partno);
647                 delete_partition(disk, part->partno);
648         }
649         disk_part_iter_exit(&piter);
650 
651         invalidate_partition(disk, 0);
652         set_capacity(disk, 0);
653         disk->flags &= ~GENHD_FL_UP;
654 
655         sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
656         bdi_unregister(&disk->queue->backing_dev_info);
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         if (!sysfs_deprecated)
666                 sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
667         pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
668         device_del(disk_to_dev(disk));
669 }
670 EXPORT_SYMBOL(del_gendisk);
671 
672 /**
673  * get_gendisk - get partitioning information for a given device
674  * @devt: device to get partitioning information for
675  * @partno: returned partition index
676  *
677  * This function gets the structure containing partitioning
678  * information for the given device @devt.
679  */
680 struct gendisk *get_gendisk(dev_t devt, int *partno)
681 {
682         struct gendisk *disk = NULL;
683 
684         if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
685                 struct kobject *kobj;
686 
687                 kobj = kobj_lookup(bdev_map, devt, partno);
688                 if (kobj)
689                         disk = dev_to_disk(kobj_to_dev(kobj));
690         } else {
691                 struct hd_struct *part;
692 
693                 spin_lock_bh(&ext_devt_lock);
694                 part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
695                 if (part && get_disk(part_to_disk(part))) {
696                         *partno = part->partno;
697                         disk = part_to_disk(part);
698                 }
699                 spin_unlock_bh(&ext_devt_lock);
700         }
701 
702         return disk;
703 }
704 EXPORT_SYMBOL(get_gendisk);
705 
706 /**
707  * bdget_disk - do bdget() by gendisk and partition number
708  * @disk: gendisk of interest
709  * @partno: partition number
710  *
711  * Find partition @partno from @disk, do bdget() on it.
712  *
713  * CONTEXT:
714  * Don't care.
715  *
716  * RETURNS:
717  * Resulting block_device on success, NULL on failure.
718  */
719 struct block_device *bdget_disk(struct gendisk *disk, int partno)
720 {
721         struct hd_struct *part;
722         struct block_device *bdev = NULL;
723 
724         part = disk_get_part(disk, partno);
725         if (part)
726                 bdev = bdget(part_devt(part));
727         disk_put_part(part);
728 
729         return bdev;
730 }
731 EXPORT_SYMBOL(bdget_disk);
732 
733 /*
734  * print a full list of all partitions - intended for places where the root
735  * filesystem can't be mounted and thus to give the victim some idea of what
736  * went wrong
737  */
738 void __init printk_all_partitions(void)
739 {
740         struct class_dev_iter iter;
741         struct device *dev;
742 
743         class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
744         while ((dev = class_dev_iter_next(&iter))) {
745                 struct gendisk *disk = dev_to_disk(dev);
746                 struct disk_part_iter piter;
747                 struct hd_struct *part;
748                 char name_buf[BDEVNAME_SIZE];
749                 char devt_buf[BDEVT_SIZE];
750 
751                 /*
752                  * Don't show empty devices or things that have been
753                  * suppressed
754                  */
755                 if (get_capacity(disk) == 0 ||
756                     (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
757                         continue;
758 
759                 /*
760                  * Note, unlike /proc/partitions, I am showing the
761                  * numbers in hex - the same format as the root=
762                  * option takes.
763                  */
764                 disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
765                 while ((part = disk_part_iter_next(&piter))) {
766                         bool is_part0 = part == &disk->part0;
767 
768                         printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
769                                bdevt_str(part_devt(part), devt_buf),
770                                (unsigned long long)part_nr_sects_read(part) >> 1
771                                , disk_name(disk, part->partno, name_buf),
772                                part->info ? part->info->uuid : "");
773                         if (is_part0) {
774                                 if (disk->driverfs_dev != NULL &&
775                                     disk->driverfs_dev->driver != NULL)
776                                         printk(" driver: %s\n",
777                                               disk->driverfs_dev->driver->name);
778                                 else
779                                         printk(" (driver?)\n");
780                         } else
781                                 printk("\n");
782                 }
783                 disk_part_iter_exit(&piter);
784         }
785         class_dev_iter_exit(&iter);
786 }
787 
788 #ifdef CONFIG_PROC_FS
789 /* iterator */
790 static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
791 {
792         loff_t skip = *pos;
793         struct class_dev_iter *iter;
794         struct device *dev;
795 
796         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
797         if (!iter)
798                 return ERR_PTR(-ENOMEM);
799 
800         seqf->private = iter;
801         class_dev_iter_init(iter, &block_class, NULL, &disk_type);
802         do {
803                 dev = class_dev_iter_next(iter);
804                 if (!dev)
805                         return NULL;
806         } while (skip--);
807 
808         return dev_to_disk(dev);
809 }
810 
811 static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
812 {
813         struct device *dev;
814 
815         (*pos)++;
816         dev = class_dev_iter_next(seqf->private);
817         if (dev)
818                 return dev_to_disk(dev);
819 
820         return NULL;
821 }
822 
823 static void disk_seqf_stop(struct seq_file *seqf, void *v)
824 {
825         struct class_dev_iter *iter = seqf->private;
826 
827         /* stop is called even after start failed :-( */
828         if (iter) {
829                 class_dev_iter_exit(iter);
830                 kfree(iter);
831                 seqf->private = NULL;
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 = kmalloc_node(sizeof(struct gendisk),
1265                                 GFP_KERNEL | __GFP_ZERO, node_id);
1266         if (disk) {
1267                 if (!init_part_stats(&disk->part0)) {
1268                         kfree(disk);
1269                         return NULL;
1270                 }
1271                 disk->node_id = node_id;
1272                 if (disk_expand_part_tbl(disk, 0)) {
1273                         free_part_stats(&disk->part0);
1274                         kfree(disk);
1275                         return NULL;
1276                 }
1277                 disk->part_tbl->part[0] = &disk->part0;
1278 
1279                 /*
1280                  * set_capacity() and get_capacity() currently don't use
1281                  * seqcounter to read/update the part0->nr_sects. Still init
1282                  * the counter as we can read the sectors in IO submission
1283                  * patch using seqence counters.
1284                  *
1285                  * TODO: Ideally set_capacity() and get_capacity() should be
1286                  * converted to make use of bd_mutex and sequence counters.
1287                  */
1288                 seqcount_init(&disk->part0.nr_sects_seq);
1289                 hd_ref_init(&disk->part0);
1290 
1291                 disk->minors = minors;
1292                 rand_initialize_disk(disk);
1293                 disk_to_dev(disk)->class = &block_class;
1294                 disk_to_dev(disk)->type = &disk_type;
1295                 device_initialize(disk_to_dev(disk));
1296         }
1297         return disk;
1298 }
1299 EXPORT_SYMBOL(alloc_disk_node);
1300 
1301 struct kobject *get_disk(struct gendisk *disk)
1302 {
1303         struct module *owner;
1304         struct kobject *kobj;
1305 
1306         if (!disk->fops)
1307                 return NULL;
1308         owner = disk->fops->owner;
1309         if (owner && !try_module_get(owner))
1310                 return NULL;
1311         kobj = kobject_get(&disk_to_dev(disk)->kobj);
1312         if (kobj == NULL) {
1313                 module_put(owner);
1314                 return NULL;
1315         }
1316         return kobj;
1317 
1318 }
1319 
1320 EXPORT_SYMBOL(get_disk);
1321 
1322 void put_disk(struct gendisk *disk)
1323 {
1324         if (disk)
1325                 kobject_put(&disk_to_dev(disk)->kobj);
1326 }
1327 
1328 EXPORT_SYMBOL(put_disk);
1329 
1330 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
1331 {
1332         char event[] = "DISK_RO=1";
1333         char *envp[] = { event, NULL };
1334 
1335         if (!ro)
1336                 event[8] = '';
1337         kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
1338 }
1339 
1340 void set_device_ro(struct block_device *bdev, int flag)
1341 {
1342         bdev->bd_part->policy = flag;
1343 }
1344 
1345 EXPORT_SYMBOL(set_device_ro);
1346 
1347 void set_disk_ro(struct gendisk *disk, int flag)
1348 {
1349         struct disk_part_iter piter;
1350         struct hd_struct *part;
1351 
1352         if (disk->part0.policy != flag) {
1353                 set_disk_ro_uevent(disk, flag);
1354                 disk->part0.policy = flag;
1355         }
1356 
1357         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
1358         while ((part = disk_part_iter_next(&piter)))
1359                 part->policy = flag;
1360         disk_part_iter_exit(&piter);
1361 }
1362 
1363 EXPORT_SYMBOL(set_disk_ro);
1364 
1365 int bdev_read_only(struct block_device *bdev)
1366 {
1367         if (!bdev)
1368                 return 0;
1369         return bdev->bd_part->policy;
1370 }
1371 
1372 EXPORT_SYMBOL(bdev_read_only);
1373 
1374 int invalidate_partition(struct gendisk *disk, int partno)
1375 {
1376         int res = 0;
1377         struct block_device *bdev = bdget_disk(disk, partno);
1378         if (bdev) {
1379                 fsync_bdev(bdev);
1380                 res = __invalidate_device(bdev, true);
1381                 bdput(bdev);
1382         }
1383         return res;
1384 }
1385 
1386 EXPORT_SYMBOL(invalidate_partition);
1387 
1388 /*
1389  * Disk events - monitor disk events like media change and eject request.
1390  */
1391 struct disk_events {
1392         struct list_head        node;           /* all disk_event's */
1393         struct gendisk          *disk;          /* the associated disk */
1394         spinlock_t              lock;
1395 
1396         struct mutex            block_mutex;    /* protects blocking */
1397         int                     block;          /* event blocking depth */
1398         unsigned int            pending;        /* events already sent out */
1399         unsigned int            clearing;       /* events being cleared */
1400 
1401         long                    poll_msecs;     /* interval, -1 for default */
1402         struct delayed_work     dwork;
1403 };
1404 
1405 static const char *disk_events_strs[] = {
1406         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "media_change",
1407         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "eject_request",
1408 };
1409 
1410 static char *disk_uevents[] = {
1411         [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "DISK_MEDIA_CHANGE=1",
1412         [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "DISK_EJECT_REQUEST=1",
1413 };
1414 
1415 /* list of all disk_events */
1416 static DEFINE_MUTEX(disk_events_mutex);
1417 static LIST_HEAD(disk_events);
1418 
1419 /* disable in-kernel polling by default */
1420 static unsigned long disk_events_dfl_poll_msecs = 0;
1421 
1422 static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
1423 {
1424         struct disk_events *ev = disk->ev;
1425         long intv_msecs = 0;
1426 
1427         /*
1428          * If device-specific poll interval is set, always use it.  If
1429          * the default is being used, poll iff there are events which
1430          * can't be monitored asynchronously.
1431          */
1432         if (ev->poll_msecs >= 0)
1433                 intv_msecs = ev->poll_msecs;
1434         else if (disk->events & ~disk->async_events)
1435                 intv_msecs = disk_events_dfl_poll_msecs;
1436 
1437         return msecs_to_jiffies(intv_msecs);
1438 }
1439 
1440 /**
1441  * disk_block_events - block and flush disk event checking
1442  * @disk: disk to block events for
1443  *
1444  * On return from this function, it is guaranteed that event checking
1445  * isn't in progress and won't happen until unblocked by
1446  * disk_unblock_events().  Events blocking is counted and the actual
1447  * unblocking happens after the matching number of unblocks are done.
1448  *
1449  * Note that this intentionally does not block event checking from
1450  * disk_clear_events().
1451  *
1452  * CONTEXT:
1453  * Might sleep.
1454  */
1455 void disk_block_events(struct gendisk *disk)
1456 {
1457         struct disk_events *ev = disk->ev;
1458         unsigned long flags;
1459         bool cancel;
1460 
1461         if (!ev)
1462                 return;
1463 
1464         /*
1465          * Outer mutex ensures that the first blocker completes canceling
1466          * the event work before further blockers are allowed to finish.
1467          */
1468         mutex_lock(&ev->block_mutex);
1469 
1470         spin_lock_irqsave(&ev->lock, flags);
1471         cancel = !ev->block++;
1472         spin_unlock_irqrestore(&ev->lock, flags);
1473 
1474         if (cancel)
1475                 cancel_delayed_work_sync(&disk->ev->dwork);
1476 
1477         mutex_unlock(&ev->block_mutex);
1478 }
1479 
1480 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
1481 {
1482         struct disk_events *ev = disk->ev;
1483         unsigned long intv;
1484         unsigned long flags;
1485 
1486         spin_lock_irqsave(&ev->lock, flags);
1487 
1488         if (WARN_ON_ONCE(ev->block <= 0))
1489                 goto out_unlock;
1490 
1491         if (--ev->block)
1492                 goto out_unlock;
1493 
1494         /*
1495          * Not exactly a latency critical operation, set poll timer
1496          * slack to 25% and kick event check.
1497          */
1498         intv = disk_events_poll_jiffies(disk);
1499         set_timer_slack(&ev->dwork.timer, intv / 4);
1500         if (check_now)
1501                 queue_delayed_work(system_freezable_wq, &ev->dwork, 0);
1502         else if (intv)
1503                 queue_delayed_work(system_freezable_wq, &ev->dwork, intv);
1504 out_unlock:
1505         spin_unlock_irqrestore(&ev->lock, flags);
1506 }
1507 
1508 /**
1509  * disk_unblock_events - unblock disk event checking
1510  * @disk: disk to unblock events for
1511  *
1512  * Undo disk_block_events().  When the block count reaches zero, it
1513  * starts events polling if configured.
1514  *
1515  * CONTEXT:
1516  * Don't care.  Safe to call from irq context.
1517  */
1518 void disk_unblock_events(struct gendisk *disk)
1519 {
1520         if (disk->ev)
1521                 __disk_unblock_events(disk, false);
1522 }
1523 
1524 /**
1525  * disk_flush_events - schedule immediate event checking and flushing
1526  * @disk: disk to check and flush events for
1527  * @mask: events to flush
1528  *
1529  * Schedule immediate event checking on @disk if not blocked.  Events in
1530  * @mask are scheduled to be cleared from the driver.  Note that this
1531  * doesn't clear the events from @disk->ev.
1532  *
1533  * CONTEXT:
1534  * If @mask is non-zero must be called with bdev->bd_mutex held.
1535  */
1536 void disk_flush_events(struct gendisk *disk, unsigned int mask)
1537 {
1538         struct disk_events *ev = disk->ev;
1539 
1540         if (!ev)
1541                 return;
1542 
1543         spin_lock_irq(&ev->lock);
1544         ev->clearing |= mask;
1545         if (!ev->block)
1546                 mod_delayed_work(system_freezable_wq, &ev->dwork, 0);
1547         spin_unlock_irq(&ev->lock);
1548 }
1549 
1550 /**
1551  * disk_clear_events - synchronously check, clear and return pending events
1552  * @disk: disk to fetch and clear events from
1553  * @mask: mask of events to be fetched and clearted
1554  *
1555  * Disk events are synchronously checked and pending events in @mask
1556  * are cleared and returned.  This ignores the block count.
1557  *
1558  * CONTEXT:
1559  * Might sleep.
1560  */
1561 unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
1562 {
1563         const struct block_device_operations *bdops = disk->fops;
1564         struct disk_events *ev = disk->ev;
1565         unsigned int pending;
1566         unsigned int clearing = mask;
1567 
1568         if (!ev) {
1569                 /* for drivers still using the old ->media_changed method */
1570                 if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
1571                     bdops->media_changed && bdops->media_changed(disk))
1572                         return DISK_EVENT_MEDIA_CHANGE;
1573                 return 0;
1574         }
1575 
1576         disk_block_events(disk);
1577 
1578         /*
1579          * store the union of mask and ev->clearing on the stack so that the
1580          * race with disk_flush_events does not cause ambiguity (ev->clearing
1581          * can still be modified even if events are blocked).
1582          */
1583         spin_lock_irq(&ev->lock);
1584         clearing |= ev->clearing;
1585         ev->clearing = 0;
1586         spin_unlock_irq(&ev->lock);
1587 
1588         disk_check_events(ev, &clearing);
1589         /*
1590          * if ev->clearing is not 0, the disk_flush_events got called in the
1591          * middle of this function, so we want to run the workfn without delay.
1592          */
1593         __disk_unblock_events(disk, ev->clearing ? true : false);
1594 
1595         /* then, fetch and clear pending events */
1596         spin_lock_irq(&ev->lock);
1597         pending = ev->pending & mask;
1598         ev->pending &= ~mask;
1599         spin_unlock_irq(&ev->lock);
1600         WARN_ON_ONCE(clearing & mask);
1601 
1602         return pending;
1603 }
1604 
1605 /*
1606  * Separate this part out so that a different pointer for clearing_ptr can be
1607  * passed in for disk_clear_events.
1608  */
1609 static void disk_events_workfn(struct work_struct *work)
1610 {
1611         struct delayed_work *dwork = to_delayed_work(work);
1612         struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
1613 
1614         disk_check_events(ev, &ev->clearing);
1615 }
1616 
1617 static void disk_check_events(struct disk_events *ev,
1618                               unsigned int *clearing_ptr)
1619 {
1620         struct gendisk *disk = ev->disk;
1621         char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
1622         unsigned int clearing = *clearing_ptr;
1623         unsigned int events;
1624         unsigned long intv;
1625         int nr_events = 0, i;
1626 
1627         /* check events */
1628         events = disk->fops->check_events(disk, clearing);
1629 
1630         /* accumulate pending events and schedule next poll if necessary */
1631         spin_lock_irq(&ev->lock);
1632 
1633         events &= ~ev->pending;
1634         ev->pending |= events;
1635         *clearing_ptr &= ~clearing;
1636 
1637         intv = disk_events_poll_jiffies(disk);
1638         if (!ev->block && intv)
1639                 queue_delayed_work(system_freezable_wq, &ev->dwork, intv);
1640 
1641         spin_unlock_irq(&ev->lock);
1642 
1643         /*
1644          * Tell userland about new events.  Only the events listed in
1645          * @disk->events are reported.  Unlisted events are processed the
1646          * same internally but never get reported to userland.
1647          */
1648         for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
1649                 if (events & disk->events & (1 << i))
1650                         envp[nr_events++] = disk_uevents[i];
1651 
1652         if (nr_events)
1653                 kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
1654 }
1655 
1656 /*
1657  * A disk events enabled device has the following sysfs nodes under
1658  * its /sys/block/X/ directory.
1659  *
1660  * events               : list of all supported events
1661  * events_async         : list of events which can be detected w/o polling
1662  * events_poll_msecs    : polling interval, 0: disable, -1: system default
1663  */
1664 static ssize_t __disk_events_show(unsigned int events, char *buf)
1665 {
1666         const char *delim = "";
1667         ssize_t pos = 0;
1668         int i;
1669 
1670         for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
1671                 if (events & (1 << i)) {
1672                         pos += sprintf(buf + pos, "%s%s",
1673                                        delim, disk_events_strs[i]);
1674                         delim = " ";
1675                 }
1676         if (pos)
1677                 pos += sprintf(buf + pos, "\n");
1678         return pos;
1679 }
1680 
1681 static ssize_t disk_events_show(struct device *dev,
1682                                 struct device_attribute *attr, char *buf)
1683 {
1684         struct gendisk *disk = dev_to_disk(dev);
1685 
1686         return __disk_events_show(disk->events, buf);
1687 }
1688 
1689 static ssize_t disk_events_async_show(struct device *dev,
1690                                       struct device_attribute *attr, char *buf)
1691 {
1692         struct gendisk *disk = dev_to_disk(dev);
1693 
1694         return __disk_events_show(disk->async_events, buf);
1695 }
1696 
1697 static ssize_t disk_events_poll_msecs_show(struct device *dev,
1698                                            struct device_attribute *attr,
1699                                            char *buf)
1700 {
1701         struct gendisk *disk = dev_to_disk(dev);
1702 
1703         return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
1704 }
1705 
1706 static ssize_t disk_events_poll_msecs_store(struct device *dev,
1707                                             struct device_attribute *attr,
1708                                             const char *buf, size_t count)
1709 {
1710         struct gendisk *disk = dev_to_disk(dev);
1711         long intv;
1712 
1713         if (!count || !sscanf(buf, "%ld", &intv))
1714                 return -EINVAL;
1715 
1716         if (intv < 0 && intv != -1)
1717                 return -EINVAL;
1718 
1719         disk_block_events(disk);
1720         disk->ev->poll_msecs = intv;
1721         __disk_unblock_events(disk, true);
1722 
1723         return count;
1724 }
1725 
1726 static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
1727 static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
1728 static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
1729                          disk_events_poll_msecs_show,
1730                          disk_events_poll_msecs_store);
1731 
1732 static const struct attribute *disk_events_attrs[] = {
1733         &dev_attr_events.attr,
1734         &dev_attr_events_async.attr,
1735         &dev_attr_events_poll_msecs.attr,
1736         NULL,
1737 };
1738 
1739 /*
1740  * The default polling interval can be specified by the kernel
1741  * parameter block.events_dfl_poll_msecs which defaults to 0
1742  * (disable).  This can also be modified runtime by writing to
1743  * /sys/module/block/events_dfl_poll_msecs.
1744  */
1745 static int disk_events_set_dfl_poll_msecs(const char *val,
1746                                           const struct kernel_param *kp)
1747 {
1748         struct disk_events *ev;
1749         int ret;
1750 
1751         ret = param_set_ulong(val, kp);
1752         if (ret < 0)
1753                 return ret;
1754 
1755         mutex_lock(&disk_events_mutex);
1756 
1757         list_for_each_entry(ev, &disk_events, node)
1758                 disk_flush_events(ev->disk, 0);
1759 
1760         mutex_unlock(&disk_events_mutex);
1761 
1762         return 0;
1763 }
1764 
1765 static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
1766         .set    = disk_events_set_dfl_poll_msecs,
1767         .get    = param_get_ulong,
1768 };
1769 
1770 #undef MODULE_PARAM_PREFIX
1771 #define MODULE_PARAM_PREFIX     "block."
1772 
1773 module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
1774                 &disk_events_dfl_poll_msecs, 0644);
1775 
1776 /*
1777  * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
1778  */
1779 static void disk_alloc_events(struct gendisk *disk)
1780 {
1781         struct disk_events *ev;
1782 
1783         if (!disk->fops->check_events)
1784                 return;
1785 
1786         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
1787         if (!ev) {
1788                 pr_warn("%s: failed to initialize events\n", disk->disk_name);
1789                 return;
1790         }
1791 
1792         INIT_LIST_HEAD(&ev->node);
1793         ev->disk = disk;
1794         spin_lock_init(&ev->lock);
1795         mutex_init(&ev->block_mutex);
1796         ev->block = 1;
1797         ev->poll_msecs = -1;
1798         INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
1799 
1800         disk->ev = ev;
1801 }
1802 
1803 static void disk_add_events(struct gendisk *disk)
1804 {
1805         if (!disk->ev)
1806                 return;
1807 
1808         /* FIXME: error handling */
1809         if (sysfs_create_files(&disk_to_dev(disk)->kobj, disk_events_attrs) < 0)
1810                 pr_warn("%s: failed to create sysfs files for events\n",
1811                         disk->disk_name);
1812 
1813         mutex_lock(&disk_events_mutex);
1814         list_add_tail(&disk->ev->node, &disk_events);
1815         mutex_unlock(&disk_events_mutex);
1816 
1817         /*
1818          * Block count is initialized to 1 and the following initial
1819          * unblock kicks it into action.
1820          */
1821         __disk_unblock_events(disk, true);
1822 }
1823 
1824 static void disk_del_events(struct gendisk *disk)
1825 {
1826         if (!disk->ev)
1827                 return;
1828 
1829         disk_block_events(disk);
1830 
1831         mutex_lock(&disk_events_mutex);
1832         list_del_init(&disk->ev->node);
1833         mutex_unlock(&disk_events_mutex);
1834 
1835         sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
1836 }
1837 
1838 static void disk_release_events(struct gendisk *disk)
1839 {
1840         /* the block count should be 1 from disk_del_events() */
1841         WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
1842         kfree(disk->ev);
1843 }
1844 

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