xref: /openbmc/linux/block/genhd.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/seq_file.h>
14 #include <linux/slab.h>
15 #include <linux/kmod.h>
16 #include <linux/kobj_map.h>
17 #include <linux/buffer_head.h>
18 #include <linux/mutex.h>
19 
20 struct kset block_subsys;
21 static DEFINE_MUTEX(block_subsys_lock);
22 
23 /*
24  * Can be deleted altogether. Later.
25  *
26  */
27 static struct blk_major_name {
28 	struct blk_major_name *next;
29 	int major;
30 	char name[16];
31 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
32 
33 /* index in the above - for now: assume no multimajor ranges */
34 static inline int major_to_index(int major)
35 {
36 	return major % BLKDEV_MAJOR_HASH_SIZE;
37 }
38 
39 #ifdef CONFIG_PROC_FS
40 
41 void blkdev_show(struct seq_file *f, off_t offset)
42 {
43 	struct blk_major_name *dp;
44 
45 	if (offset < BLKDEV_MAJOR_HASH_SIZE) {
46 		mutex_lock(&block_subsys_lock);
47 		for (dp = major_names[offset]; dp; dp = dp->next)
48 			seq_printf(f, "%3d %s\n", dp->major, dp->name);
49 		mutex_unlock(&block_subsys_lock);
50 	}
51 }
52 
53 #endif /* CONFIG_PROC_FS */
54 
55 int register_blkdev(unsigned int major, const char *name)
56 {
57 	struct blk_major_name **n, *p;
58 	int index, ret = 0;
59 
60 	mutex_lock(&block_subsys_lock);
61 
62 	/* temporary */
63 	if (major == 0) {
64 		for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
65 			if (major_names[index] == NULL)
66 				break;
67 		}
68 
69 		if (index == 0) {
70 			printk("register_blkdev: failed to get major for %s\n",
71 			       name);
72 			ret = -EBUSY;
73 			goto out;
74 		}
75 		major = index;
76 		ret = major;
77 	}
78 
79 	p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
80 	if (p == NULL) {
81 		ret = -ENOMEM;
82 		goto out;
83 	}
84 
85 	p->major = major;
86 	strlcpy(p->name, name, sizeof(p->name));
87 	p->next = NULL;
88 	index = major_to_index(major);
89 
90 	for (n = &major_names[index]; *n; n = &(*n)->next) {
91 		if ((*n)->major == major)
92 			break;
93 	}
94 	if (!*n)
95 		*n = p;
96 	else
97 		ret = -EBUSY;
98 
99 	if (ret < 0) {
100 		printk("register_blkdev: cannot get major %d for %s\n",
101 		       major, name);
102 		kfree(p);
103 	}
104 out:
105 	mutex_unlock(&block_subsys_lock);
106 	return ret;
107 }
108 
109 EXPORT_SYMBOL(register_blkdev);
110 
111 /* todo: make void - error printk here */
112 int unregister_blkdev(unsigned int major, const char *name)
113 {
114 	struct blk_major_name **n;
115 	struct blk_major_name *p = NULL;
116 	int index = major_to_index(major);
117 	int ret = 0;
118 
119 	mutex_lock(&block_subsys_lock);
120 	for (n = &major_names[index]; *n; n = &(*n)->next)
121 		if ((*n)->major == major)
122 			break;
123 	if (!*n || strcmp((*n)->name, name))
124 		ret = -EINVAL;
125 	else {
126 		p = *n;
127 		*n = p->next;
128 	}
129 	mutex_unlock(&block_subsys_lock);
130 	kfree(p);
131 
132 	return ret;
133 }
134 
135 EXPORT_SYMBOL(unregister_blkdev);
136 
137 static struct kobj_map *bdev_map;
138 
139 /*
140  * Register device numbers dev..(dev+range-1)
141  * range must be nonzero
142  * The hash chain is sorted on range, so that subranges can override.
143  */
144 void blk_register_region(dev_t dev, unsigned long range, struct module *module,
145 			 struct kobject *(*probe)(dev_t, int *, void *),
146 			 int (*lock)(dev_t, void *), void *data)
147 {
148 	kobj_map(bdev_map, dev, range, module, probe, lock, data);
149 }
150 
151 EXPORT_SYMBOL(blk_register_region);
152 
153 void blk_unregister_region(dev_t dev, unsigned long range)
154 {
155 	kobj_unmap(bdev_map, dev, range);
156 }
157 
158 EXPORT_SYMBOL(blk_unregister_region);
159 
160 static struct kobject *exact_match(dev_t dev, int *part, void *data)
161 {
162 	struct gendisk *p = data;
163 	return &p->kobj;
164 }
165 
166 static int exact_lock(dev_t dev, void *data)
167 {
168 	struct gendisk *p = data;
169 
170 	if (!get_disk(p))
171 		return -1;
172 	return 0;
173 }
174 
175 /**
176  * add_disk - add partitioning information to kernel list
177  * @disk: per-device partitioning information
178  *
179  * This function registers the partitioning information in @disk
180  * with the kernel.
181  */
182 void add_disk(struct gendisk *disk)
183 {
184 	disk->flags |= GENHD_FL_UP;
185 	blk_register_region(MKDEV(disk->major, disk->first_minor),
186 			    disk->minors, NULL, exact_match, exact_lock, disk);
187 	register_disk(disk);
188 	blk_register_queue(disk);
189 }
190 
191 EXPORT_SYMBOL(add_disk);
192 EXPORT_SYMBOL(del_gendisk);	/* in partitions/check.c */
193 
194 void unlink_gendisk(struct gendisk *disk)
195 {
196 	blk_unregister_queue(disk);
197 	blk_unregister_region(MKDEV(disk->major, disk->first_minor),
198 			      disk->minors);
199 }
200 
201 #define to_disk(obj) container_of(obj,struct gendisk,kobj)
202 
203 /**
204  * get_gendisk - get partitioning information for a given device
205  * @dev: device to get partitioning information for
206  *
207  * This function gets the structure containing partitioning
208  * information for the given device @dev.
209  */
210 struct gendisk *get_gendisk(dev_t dev, int *part)
211 {
212 	struct kobject *kobj = kobj_lookup(bdev_map, dev, part);
213 	return  kobj ? to_disk(kobj) : NULL;
214 }
215 
216 /*
217  * print a full list of all partitions - intended for places where the root
218  * filesystem can't be mounted and thus to give the victim some idea of what
219  * went wrong
220  */
221 void __init printk_all_partitions(void)
222 {
223 	int n;
224 	struct gendisk *sgp;
225 
226 	mutex_lock(&block_subsys_lock);
227 	/* For each block device... */
228 	list_for_each_entry(sgp, &block_subsys.list, kobj.entry) {
229 		char buf[BDEVNAME_SIZE];
230 		/*
231 		 * Don't show empty devices or things that have been surpressed
232 		 */
233 		if (get_capacity(sgp) == 0 ||
234 		    (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
235 			continue;
236 
237 		/*
238 		 * Note, unlike /proc/partitions, I am showing the numbers in
239 		 * hex - the same format as the root= option takes.
240 		 */
241 		printk("%02x%02x %10llu %s",
242 			sgp->major, sgp->first_minor,
243 			(unsigned long long)get_capacity(sgp) >> 1,
244 			disk_name(sgp, 0, buf));
245 		if (sgp->driverfs_dev != NULL &&
246 		    sgp->driverfs_dev->driver != NULL)
247 			printk(" driver: %s\n",
248 				sgp->driverfs_dev->driver->name);
249 		else
250 			printk(" (driver?)\n");
251 
252 		/* now show the partitions */
253 		for (n = 0; n < sgp->minors - 1; ++n) {
254 			if (sgp->part[n] == NULL)
255 				continue;
256 			if (sgp->part[n]->nr_sects == 0)
257 				continue;
258 			printk("  %02x%02x %10llu %s\n",
259 				sgp->major, n + 1 + sgp->first_minor,
260 				(unsigned long long)sgp->part[n]->nr_sects >> 1,
261 				disk_name(sgp, n + 1, buf));
262 		} /* partition subloop */
263 	} /* Block device loop */
264 
265 	mutex_unlock(&block_subsys_lock);
266 	return;
267 }
268 
269 #ifdef CONFIG_PROC_FS
270 /* iterator */
271 static void *part_start(struct seq_file *part, loff_t *pos)
272 {
273 	struct list_head *p;
274 	loff_t l = *pos;
275 
276 	mutex_lock(&block_subsys_lock);
277 	list_for_each(p, &block_subsys.list)
278 		if (!l--)
279 			return list_entry(p, struct gendisk, kobj.entry);
280 	return NULL;
281 }
282 
283 static void *part_next(struct seq_file *part, void *v, loff_t *pos)
284 {
285 	struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
286 	++*pos;
287 	return p==&block_subsys.list ? NULL :
288 		list_entry(p, struct gendisk, kobj.entry);
289 }
290 
291 static void part_stop(struct seq_file *part, void *v)
292 {
293 	mutex_unlock(&block_subsys_lock);
294 }
295 
296 static int show_partition(struct seq_file *part, void *v)
297 {
298 	struct gendisk *sgp = v;
299 	int n;
300 	char buf[BDEVNAME_SIZE];
301 
302 	if (&sgp->kobj.entry == block_subsys.list.next)
303 		seq_puts(part, "major minor  #blocks  name\n\n");
304 
305 	/* Don't show non-partitionable removeable devices or empty devices */
306 	if (!get_capacity(sgp) ||
307 			(sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
308 		return 0;
309 	if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
310 		return 0;
311 
312 	/* show the full disk and all non-0 size partitions of it */
313 	seq_printf(part, "%4d  %4d %10llu %s\n",
314 		sgp->major, sgp->first_minor,
315 		(unsigned long long)get_capacity(sgp) >> 1,
316 		disk_name(sgp, 0, buf));
317 	for (n = 0; n < sgp->minors - 1; n++) {
318 		if (!sgp->part[n])
319 			continue;
320 		if (sgp->part[n]->nr_sects == 0)
321 			continue;
322 		seq_printf(part, "%4d  %4d %10llu %s\n",
323 			sgp->major, n + 1 + sgp->first_minor,
324 			(unsigned long long)sgp->part[n]->nr_sects >> 1 ,
325 			disk_name(sgp, n + 1, buf));
326 	}
327 
328 	return 0;
329 }
330 
331 struct seq_operations partitions_op = {
332 	.start =part_start,
333 	.next =	part_next,
334 	.stop =	part_stop,
335 	.show =	show_partition
336 };
337 #endif
338 
339 
340 extern int blk_dev_init(void);
341 
342 static struct kobject *base_probe(dev_t dev, int *part, void *data)
343 {
344 	if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
345 		/* Make old-style 2.4 aliases work */
346 		request_module("block-major-%d", MAJOR(dev));
347 	return NULL;
348 }
349 
350 static int __init genhd_device_init(void)
351 {
352 	int err;
353 
354 	bdev_map = kobj_map_init(base_probe, &block_subsys_lock);
355 	blk_dev_init();
356 	err = subsystem_register(&block_subsys);
357 	if (err < 0)
358 		printk(KERN_WARNING "%s: subsystem_register error: %d\n",
359 			__FUNCTION__, err);
360 	return err;
361 }
362 
363 subsys_initcall(genhd_device_init);
364 
365 
366 
367 /*
368  * kobject & sysfs bindings for block devices
369  */
370 static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
371 			      char *page)
372 {
373 	struct gendisk *disk = to_disk(kobj);
374 	struct disk_attribute *disk_attr =
375 		container_of(attr,struct disk_attribute,attr);
376 	ssize_t ret = -EIO;
377 
378 	if (disk_attr->show)
379 		ret = disk_attr->show(disk,page);
380 	return ret;
381 }
382 
383 static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
384 			       const char *page, size_t count)
385 {
386 	struct gendisk *disk = to_disk(kobj);
387 	struct disk_attribute *disk_attr =
388 		container_of(attr,struct disk_attribute,attr);
389 	ssize_t ret = 0;
390 
391 	if (disk_attr->store)
392 		ret = disk_attr->store(disk, page, count);
393 	return ret;
394 }
395 
396 static struct sysfs_ops disk_sysfs_ops = {
397 	.show	= &disk_attr_show,
398 	.store	= &disk_attr_store,
399 };
400 
401 static ssize_t disk_uevent_store(struct gendisk * disk,
402 				 const char *buf, size_t count)
403 {
404 	kobject_uevent(&disk->kobj, KOBJ_ADD);
405 	return count;
406 }
407 static ssize_t disk_dev_read(struct gendisk * disk, char *page)
408 {
409 	dev_t base = MKDEV(disk->major, disk->first_minor);
410 	return print_dev_t(page, base);
411 }
412 static ssize_t disk_range_read(struct gendisk * disk, char *page)
413 {
414 	return sprintf(page, "%d\n", disk->minors);
415 }
416 static ssize_t disk_removable_read(struct gendisk * disk, char *page)
417 {
418 	return sprintf(page, "%d\n",
419 		       (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
420 
421 }
422 static ssize_t disk_size_read(struct gendisk * disk, char *page)
423 {
424 	return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk));
425 }
426 
427 static ssize_t disk_stats_read(struct gendisk * disk, char *page)
428 {
429 	preempt_disable();
430 	disk_round_stats(disk);
431 	preempt_enable();
432 	return sprintf(page,
433 		"%8lu %8lu %8llu %8u "
434 		"%8lu %8lu %8llu %8u "
435 		"%8u %8u %8u"
436 		"\n",
437 		disk_stat_read(disk, ios[READ]),
438 		disk_stat_read(disk, merges[READ]),
439 		(unsigned long long)disk_stat_read(disk, sectors[READ]),
440 		jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
441 		disk_stat_read(disk, ios[WRITE]),
442 		disk_stat_read(disk, merges[WRITE]),
443 		(unsigned long long)disk_stat_read(disk, sectors[WRITE]),
444 		jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),
445 		disk->in_flight,
446 		jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
447 		jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
448 }
449 static struct disk_attribute disk_attr_uevent = {
450 	.attr = {.name = "uevent", .mode = S_IWUSR },
451 	.store	= disk_uevent_store
452 };
453 static struct disk_attribute disk_attr_dev = {
454 	.attr = {.name = "dev", .mode = S_IRUGO },
455 	.show	= disk_dev_read
456 };
457 static struct disk_attribute disk_attr_range = {
458 	.attr = {.name = "range", .mode = S_IRUGO },
459 	.show	= disk_range_read
460 };
461 static struct disk_attribute disk_attr_removable = {
462 	.attr = {.name = "removable", .mode = S_IRUGO },
463 	.show	= disk_removable_read
464 };
465 static struct disk_attribute disk_attr_size = {
466 	.attr = {.name = "size", .mode = S_IRUGO },
467 	.show	= disk_size_read
468 };
469 static struct disk_attribute disk_attr_stat = {
470 	.attr = {.name = "stat", .mode = S_IRUGO },
471 	.show	= disk_stats_read
472 };
473 
474 #ifdef CONFIG_FAIL_MAKE_REQUEST
475 
476 static ssize_t disk_fail_store(struct gendisk * disk,
477 			       const char *buf, size_t count)
478 {
479 	int i;
480 
481 	if (count > 0 && sscanf(buf, "%d", &i) > 0) {
482 		if (i == 0)
483 			disk->flags &= ~GENHD_FL_FAIL;
484 		else
485 			disk->flags |= GENHD_FL_FAIL;
486 	}
487 
488 	return count;
489 }
490 static ssize_t disk_fail_read(struct gendisk * disk, char *page)
491 {
492 	return sprintf(page, "%d\n", disk->flags & GENHD_FL_FAIL ? 1 : 0);
493 }
494 static struct disk_attribute disk_attr_fail = {
495 	.attr = {.name = "make-it-fail", .mode = S_IRUGO | S_IWUSR },
496 	.store	= disk_fail_store,
497 	.show	= disk_fail_read
498 };
499 
500 #endif
501 
502 static struct attribute * default_attrs[] = {
503 	&disk_attr_uevent.attr,
504 	&disk_attr_dev.attr,
505 	&disk_attr_range.attr,
506 	&disk_attr_removable.attr,
507 	&disk_attr_size.attr,
508 	&disk_attr_stat.attr,
509 #ifdef CONFIG_FAIL_MAKE_REQUEST
510 	&disk_attr_fail.attr,
511 #endif
512 	NULL,
513 };
514 
515 static void disk_release(struct kobject * kobj)
516 {
517 	struct gendisk *disk = to_disk(kobj);
518 	kfree(disk->random);
519 	kfree(disk->part);
520 	free_disk_stats(disk);
521 	kfree(disk);
522 }
523 
524 static struct kobj_type ktype_block = {
525 	.release	= disk_release,
526 	.sysfs_ops	= &disk_sysfs_ops,
527 	.default_attrs	= default_attrs,
528 };
529 
530 extern struct kobj_type ktype_part;
531 
532 static int block_uevent_filter(struct kset *kset, struct kobject *kobj)
533 {
534 	struct kobj_type *ktype = get_ktype(kobj);
535 
536 	return ((ktype == &ktype_block) || (ktype == &ktype_part));
537 }
538 
539 static int block_uevent(struct kset *kset, struct kobject *kobj, char **envp,
540 			 int num_envp, char *buffer, int buffer_size)
541 {
542 	struct kobj_type *ktype = get_ktype(kobj);
543 	struct device *physdev;
544 	struct gendisk *disk;
545 	struct hd_struct *part;
546 	int length = 0;
547 	int i = 0;
548 
549 	if (ktype == &ktype_block) {
550 		disk = container_of(kobj, struct gendisk, kobj);
551 		add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
552 			       &length, "MINOR=%u", disk->first_minor);
553 	} else if (ktype == &ktype_part) {
554 		disk = container_of(kobj->parent, struct gendisk, kobj);
555 		part = container_of(kobj, struct hd_struct, kobj);
556 		add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
557 			       &length, "MINOR=%u",
558 			       disk->first_minor + part->partno);
559 	} else
560 		return 0;
561 
562 	add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
563 		       "MAJOR=%u", disk->major);
564 
565 	/* add physical device, backing this device  */
566 	physdev = disk->driverfs_dev;
567 	if (physdev) {
568 		char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL);
569 
570 		add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
571 			       &length, "PHYSDEVPATH=%s", path);
572 		kfree(path);
573 
574 		if (physdev->bus)
575 			add_uevent_var(envp, num_envp, &i,
576 				       buffer, buffer_size, &length,
577 				       "PHYSDEVBUS=%s",
578 				       physdev->bus->name);
579 
580 		if (physdev->driver)
581 			add_uevent_var(envp, num_envp, &i,
582 				       buffer, buffer_size, &length,
583 				       "PHYSDEVDRIVER=%s",
584 				       physdev->driver->name);
585 	}
586 
587 	/* terminate, set to next free slot, shrink available space */
588 	envp[i] = NULL;
589 	envp = &envp[i];
590 	num_envp -= i;
591 	buffer = &buffer[length];
592 	buffer_size -= length;
593 
594 	return 0;
595 }
596 
597 static struct kset_uevent_ops block_uevent_ops = {
598 	.filter		= block_uevent_filter,
599 	.uevent		= block_uevent,
600 };
601 
602 decl_subsys(block, &ktype_block, &block_uevent_ops);
603 
604 /*
605  * aggregate disk stat collector.  Uses the same stats that the sysfs
606  * entries do, above, but makes them available through one seq_file.
607  * Watching a few disks may be efficient through sysfs, but watching
608  * all of them will be more efficient through this interface.
609  *
610  * The output looks suspiciously like /proc/partitions with a bunch of
611  * extra fields.
612  */
613 
614 /* iterator */
615 static void *diskstats_start(struct seq_file *part, loff_t *pos)
616 {
617 	loff_t k = *pos;
618 	struct list_head *p;
619 
620 	mutex_lock(&block_subsys_lock);
621 	list_for_each(p, &block_subsys.list)
622 		if (!k--)
623 			return list_entry(p, struct gendisk, kobj.entry);
624 	return NULL;
625 }
626 
627 static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
628 {
629 	struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
630 	++*pos;
631 	return p==&block_subsys.list ? NULL :
632 		list_entry(p, struct gendisk, kobj.entry);
633 }
634 
635 static void diskstats_stop(struct seq_file *part, void *v)
636 {
637 	mutex_unlock(&block_subsys_lock);
638 }
639 
640 static int diskstats_show(struct seq_file *s, void *v)
641 {
642 	struct gendisk *gp = v;
643 	char buf[BDEVNAME_SIZE];
644 	int n = 0;
645 
646 	/*
647 	if (&sgp->kobj.entry == block_subsys.kset.list.next)
648 		seq_puts(s,	"major minor name"
649 				"     rio rmerge rsect ruse wio wmerge "
650 				"wsect wuse running use aveq"
651 				"\n\n");
652 	*/
653 
654 	preempt_disable();
655 	disk_round_stats(gp);
656 	preempt_enable();
657 	seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
658 		gp->major, n + gp->first_minor, disk_name(gp, n, buf),
659 		disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
660 		(unsigned long long)disk_stat_read(gp, sectors[0]),
661 		jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
662 		disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
663 		(unsigned long long)disk_stat_read(gp, sectors[1]),
664 		jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
665 		gp->in_flight,
666 		jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
667 		jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));
668 
669 	/* now show all non-0 size partitions of it */
670 	for (n = 0; n < gp->minors - 1; n++) {
671 		struct hd_struct *hd = gp->part[n];
672 
673 		if (hd && hd->nr_sects)
674 			seq_printf(s, "%4d %4d %s %u %u %u %u\n",
675 				gp->major, n + gp->first_minor + 1,
676 				disk_name(gp, n + 1, buf),
677 				hd->ios[0], hd->sectors[0],
678 				hd->ios[1], hd->sectors[1]);
679 	}
680 
681 	return 0;
682 }
683 
684 struct seq_operations diskstats_op = {
685 	.start	= diskstats_start,
686 	.next	= diskstats_next,
687 	.stop	= diskstats_stop,
688 	.show	= diskstats_show
689 };
690 
691 struct gendisk *alloc_disk(int minors)
692 {
693 	return alloc_disk_node(minors, -1);
694 }
695 
696 struct gendisk *alloc_disk_node(int minors, int node_id)
697 {
698 	struct gendisk *disk;
699 
700 	disk = kmalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
701 	if (disk) {
702 		memset(disk, 0, sizeof(struct gendisk));
703 		if (!init_disk_stats(disk)) {
704 			kfree(disk);
705 			return NULL;
706 		}
707 		if (minors > 1) {
708 			int size = (minors - 1) * sizeof(struct hd_struct *);
709 			disk->part = kmalloc_node(size, GFP_KERNEL, node_id);
710 			if (!disk->part) {
711 				kfree(disk);
712 				return NULL;
713 			}
714 			memset(disk->part, 0, size);
715 		}
716 		disk->minors = minors;
717 		kobj_set_kset_s(disk,block_subsys);
718 		kobject_init(&disk->kobj);
719 		rand_initialize_disk(disk);
720 	}
721 	return disk;
722 }
723 
724 EXPORT_SYMBOL(alloc_disk);
725 EXPORT_SYMBOL(alloc_disk_node);
726 
727 struct kobject *get_disk(struct gendisk *disk)
728 {
729 	struct module *owner;
730 	struct kobject *kobj;
731 
732 	if (!disk->fops)
733 		return NULL;
734 	owner = disk->fops->owner;
735 	if (owner && !try_module_get(owner))
736 		return NULL;
737 	kobj = kobject_get(&disk->kobj);
738 	if (kobj == NULL) {
739 		module_put(owner);
740 		return NULL;
741 	}
742 	return kobj;
743 
744 }
745 
746 EXPORT_SYMBOL(get_disk);
747 
748 void put_disk(struct gendisk *disk)
749 {
750 	if (disk)
751 		kobject_put(&disk->kobj);
752 }
753 
754 EXPORT_SYMBOL(put_disk);
755 
756 void set_device_ro(struct block_device *bdev, int flag)
757 {
758 	if (bdev->bd_contains != bdev)
759 		bdev->bd_part->policy = flag;
760 	else
761 		bdev->bd_disk->policy = flag;
762 }
763 
764 EXPORT_SYMBOL(set_device_ro);
765 
766 void set_disk_ro(struct gendisk *disk, int flag)
767 {
768 	int i;
769 	disk->policy = flag;
770 	for (i = 0; i < disk->minors - 1; i++)
771 		if (disk->part[i]) disk->part[i]->policy = flag;
772 }
773 
774 EXPORT_SYMBOL(set_disk_ro);
775 
776 int bdev_read_only(struct block_device *bdev)
777 {
778 	if (!bdev)
779 		return 0;
780 	else if (bdev->bd_contains != bdev)
781 		return bdev->bd_part->policy;
782 	else
783 		return bdev->bd_disk->policy;
784 }
785 
786 EXPORT_SYMBOL(bdev_read_only);
787 
788 int invalidate_partition(struct gendisk *disk, int index)
789 {
790 	int res = 0;
791 	struct block_device *bdev = bdget_disk(disk, index);
792 	if (bdev) {
793 		fsync_bdev(bdev);
794 		res = __invalidate_device(bdev);
795 		bdput(bdev);
796 	}
797 	return res;
798 }
799 
800 EXPORT_SYMBOL(invalidate_partition);
801