0a8b0ad0c7e25c803ca57a9a814934620ad80039
[linux-2.6.git] / fs / partitions / check.c
1 /*
2  *  fs/partitions/check.c
3  *
4  *  Code extracted from drivers/block/genhd.c
5  *  Copyright (C) 1991-1998  Linus Torvalds
6  *  Re-organised Feb 1998 Russell King
7  *
8  *  We now have independent partition support from the
9  *  block drivers, which allows all the partition code to
10  *  be grouped in one location, and it to be mostly self
11  *  contained.
12  *
13  *  Added needed MAJORS for new pairs, {hdi,hdj}, {hdk,hdl}
14  */
15
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/fs.h>
19 #include <linux/slab.h>
20 #include <linux/kmod.h>
21 #include <linux/ctype.h>
22 #include <linux/genhd.h>
23 #include <linux/blktrace_api.h>
24
25 #include "check.h"
26
27 #include "acorn.h"
28 #include "amiga.h"
29 #include "atari.h"
30 #include "ldm.h"
31 #include "mac.h"
32 #include "msdos.h"
33 #include "osf.h"
34 #include "sgi.h"
35 #include "sun.h"
36 #include "ibm.h"
37 #include "ultrix.h"
38 #include "efi.h"
39 #include "karma.h"
40 #include "sysv68.h"
41
42 #ifdef CONFIG_BLK_DEV_MD
43 extern void md_autodetect_dev(dev_t dev);
44 #endif
45
46 int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
47
48 static int (*check_part[])(struct parsed_partitions *) = {
49         /*
50          * Probe partition formats with tables at disk address 0
51          * that also have an ADFS boot block at 0xdc0.
52          */
53 #ifdef CONFIG_ACORN_PARTITION_ICS
54         adfspart_check_ICS,
55 #endif
56 #ifdef CONFIG_ACORN_PARTITION_POWERTEC
57         adfspart_check_POWERTEC,
58 #endif
59 #ifdef CONFIG_ACORN_PARTITION_EESOX
60         adfspart_check_EESOX,
61 #endif
62
63         /*
64          * Now move on to formats that only have partition info at
65          * disk address 0xdc0.  Since these may also have stale
66          * PC/BIOS partition tables, they need to come before
67          * the msdos entry.
68          */
69 #ifdef CONFIG_ACORN_PARTITION_CUMANA
70         adfspart_check_CUMANA,
71 #endif
72 #ifdef CONFIG_ACORN_PARTITION_ADFS
73         adfspart_check_ADFS,
74 #endif
75
76 #ifdef CONFIG_EFI_PARTITION
77         efi_partition,          /* this must come before msdos */
78 #endif
79 #ifdef CONFIG_SGI_PARTITION
80         sgi_partition,
81 #endif
82 #ifdef CONFIG_LDM_PARTITION
83         ldm_partition,          /* this must come before msdos */
84 #endif
85 #ifdef CONFIG_MSDOS_PARTITION
86         msdos_partition,
87 #endif
88 #ifdef CONFIG_OSF_PARTITION
89         osf_partition,
90 #endif
91 #ifdef CONFIG_SUN_PARTITION
92         sun_partition,
93 #endif
94 #ifdef CONFIG_AMIGA_PARTITION
95         amiga_partition,
96 #endif
97 #ifdef CONFIG_ATARI_PARTITION
98         atari_partition,
99 #endif
100 #ifdef CONFIG_MAC_PARTITION
101         mac_partition,
102 #endif
103 #ifdef CONFIG_ULTRIX_PARTITION
104         ultrix_partition,
105 #endif
106 #ifdef CONFIG_IBM_PARTITION
107         ibm_partition,
108 #endif
109 #ifdef CONFIG_KARMA_PARTITION
110         karma_partition,
111 #endif
112 #ifdef CONFIG_SYSV68_PARTITION
113         sysv68_partition,
114 #endif
115         NULL
116 };
117  
118 /*
119  * disk_name() is used by partition check code and the genhd driver.
120  * It formats the devicename of the indicated disk into
121  * the supplied buffer (of size at least 32), and returns
122  * a pointer to that same buffer (for convenience).
123  */
124
125 char *disk_name(struct gendisk *hd, int partno, char *buf)
126 {
127         if (!partno)
128                 snprintf(buf, BDEVNAME_SIZE, "%s", hd->disk_name);
129         else if (isdigit(hd->disk_name[strlen(hd->disk_name)-1]))
130                 snprintf(buf, BDEVNAME_SIZE, "%sp%d", hd->disk_name, partno);
131         else
132                 snprintf(buf, BDEVNAME_SIZE, "%s%d", hd->disk_name, partno);
133
134         return buf;
135 }
136
137 const char *bdevname(struct block_device *bdev, char *buf)
138 {
139         return disk_name(bdev->bd_disk, bdev->bd_part->partno, buf);
140 }
141
142 EXPORT_SYMBOL(bdevname);
143
144 /*
145  * There's very little reason to use this, you should really
146  * have a struct block_device just about everywhere and use
147  * bdevname() instead.
148  */
149 const char *__bdevname(dev_t dev, char *buffer)
150 {
151         scnprintf(buffer, BDEVNAME_SIZE, "unknown-block(%u,%u)",
152                                 MAJOR(dev), MINOR(dev));
153         return buffer;
154 }
155
156 EXPORT_SYMBOL(__bdevname);
157
158 static struct parsed_partitions *
159 check_partition(struct gendisk *hd, struct block_device *bdev)
160 {
161         struct parsed_partitions *state;
162         int i, res, err;
163
164         state = kzalloc(sizeof(struct parsed_partitions), GFP_KERNEL);
165         if (!state)
166                 return NULL;
167         state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
168         if (!state->pp_buf) {
169                 kfree(state);
170                 return NULL;
171         }
172         state->pp_buf[0] = '\0';
173
174         state->bdev = bdev;
175         disk_name(hd, 0, state->name);
176         snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
177         if (isdigit(state->name[strlen(state->name)-1]))
178                 sprintf(state->name, "p");
179
180         state->limit = disk_max_parts(hd);
181         i = res = err = 0;
182         while (!res && check_part[i]) {
183                 memset(&state->parts, 0, sizeof(state->parts));
184                 res = check_part[i++](state);
185                 if (res < 0) {
186                         /* We have hit an I/O error which we don't report now.
187                         * But record it, and let the others do their job.
188                         */
189                         err = res;
190                         res = 0;
191                 }
192
193         }
194         if (res > 0) {
195                 printk(KERN_INFO "%s", state->pp_buf);
196
197                 free_page((unsigned long)state->pp_buf);
198                 return state;
199         }
200         if (state->access_beyond_eod)
201                 err = -ENOSPC;
202         if (err)
203         /* The partition is unrecognized. So report I/O errors if there were any */
204                 res = err;
205         if (!res)
206                 strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
207         else if (warn_no_part)
208                 strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
209
210         printk(KERN_INFO "%s", state->pp_buf);
211
212         free_page((unsigned long)state->pp_buf);
213         kfree(state);
214         return ERR_PTR(res);
215 }
216
217 static ssize_t part_partition_show(struct device *dev,
218                                    struct device_attribute *attr, char *buf)
219 {
220         struct hd_struct *p = dev_to_part(dev);
221
222         return sprintf(buf, "%d\n", p->partno);
223 }
224
225 static ssize_t part_start_show(struct device *dev,
226                                struct device_attribute *attr, char *buf)
227 {
228         struct hd_struct *p = dev_to_part(dev);
229
230         return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect);
231 }
232
233 ssize_t part_size_show(struct device *dev,
234                        struct device_attribute *attr, char *buf)
235 {
236         struct hd_struct *p = dev_to_part(dev);
237         return sprintf(buf, "%llu\n",(unsigned long long)p->nr_sects);
238 }
239
240 ssize_t part_alignment_offset_show(struct device *dev,
241                                    struct device_attribute *attr, char *buf)
242 {
243         struct hd_struct *p = dev_to_part(dev);
244         return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset);
245 }
246
247 ssize_t part_discard_alignment_show(struct device *dev,
248                                    struct device_attribute *attr, char *buf)
249 {
250         struct hd_struct *p = dev_to_part(dev);
251         return sprintf(buf, "%u\n", p->discard_alignment);
252 }
253
254 ssize_t part_stat_show(struct device *dev,
255                        struct device_attribute *attr, char *buf)
256 {
257         struct hd_struct *p = dev_to_part(dev);
258         int cpu;
259
260         cpu = part_stat_lock();
261         part_round_stats(cpu, p);
262         part_stat_unlock();
263         return sprintf(buf,
264                 "%8lu %8lu %8llu %8u "
265                 "%8lu %8lu %8llu %8u "
266                 "%8u %8u %8u"
267                 "\n",
268                 part_stat_read(p, ios[READ]),
269                 part_stat_read(p, merges[READ]),
270                 (unsigned long long)part_stat_read(p, sectors[READ]),
271                 jiffies_to_msecs(part_stat_read(p, ticks[READ])),
272                 part_stat_read(p, ios[WRITE]),
273                 part_stat_read(p, merges[WRITE]),
274                 (unsigned long long)part_stat_read(p, sectors[WRITE]),
275                 jiffies_to_msecs(part_stat_read(p, ticks[WRITE])),
276                 part_in_flight(p),
277                 jiffies_to_msecs(part_stat_read(p, io_ticks)),
278                 jiffies_to_msecs(part_stat_read(p, time_in_queue)));
279 }
280
281 ssize_t part_inflight_show(struct device *dev,
282                         struct device_attribute *attr, char *buf)
283 {
284         struct hd_struct *p = dev_to_part(dev);
285
286         return sprintf(buf, "%8u %8u\n", p->in_flight[0], p->in_flight[1]);
287 }
288
289 #ifdef CONFIG_FAIL_MAKE_REQUEST
290 ssize_t part_fail_show(struct device *dev,
291                        struct device_attribute *attr, char *buf)
292 {
293         struct hd_struct *p = dev_to_part(dev);
294
295         return sprintf(buf, "%d\n", p->make_it_fail);
296 }
297
298 ssize_t part_fail_store(struct device *dev,
299                         struct device_attribute *attr,
300                         const char *buf, size_t count)
301 {
302         struct hd_struct *p = dev_to_part(dev);
303         int i;
304
305         if (count > 0 && sscanf(buf, "%d", &i) > 0)
306                 p->make_it_fail = (i == 0) ? 0 : 1;
307
308         return count;
309 }
310 #endif
311
312 static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL);
313 static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL);
314 static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
315 static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL);
316 static DEVICE_ATTR(discard_alignment, S_IRUGO, part_discard_alignment_show,
317                    NULL);
318 static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
319 static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
320 #ifdef CONFIG_FAIL_MAKE_REQUEST
321 static struct device_attribute dev_attr_fail =
322         __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
323 #endif
324
325 static struct attribute *part_attrs[] = {
326         &dev_attr_partition.attr,
327         &dev_attr_start.attr,
328         &dev_attr_size.attr,
329         &dev_attr_alignment_offset.attr,
330         &dev_attr_discard_alignment.attr,
331         &dev_attr_stat.attr,
332         &dev_attr_inflight.attr,
333 #ifdef CONFIG_FAIL_MAKE_REQUEST
334         &dev_attr_fail.attr,
335 #endif
336         NULL
337 };
338
339 static struct attribute_group part_attr_group = {
340         .attrs = part_attrs,
341 };
342
343 static const struct attribute_group *part_attr_groups[] = {
344         &part_attr_group,
345 #ifdef CONFIG_BLK_DEV_IO_TRACE
346         &blk_trace_attr_group,
347 #endif
348         NULL
349 };
350
351 static void part_release(struct device *dev)
352 {
353         struct hd_struct *p = dev_to_part(dev);
354         free_part_stats(p);
355         free_part_info(p);
356         kfree(p);
357 }
358
359 struct device_type part_type = {
360         .name           = "partition",
361         .groups         = part_attr_groups,
362         .release        = part_release,
363 };
364
365 static void delete_partition_rcu_cb(struct rcu_head *head)
366 {
367         struct hd_struct *part = container_of(head, struct hd_struct, rcu_head);
368
369         part->start_sect = 0;
370         part->nr_sects = 0;
371         part_stat_set_all(part, 0);
372         put_device(part_to_dev(part));
373 }
374
375 void delete_partition(struct gendisk *disk, int partno)
376 {
377         struct disk_part_tbl *ptbl = disk->part_tbl;
378         struct hd_struct *part;
379
380         if (partno >= ptbl->len)
381                 return;
382
383         part = ptbl->part[partno];
384         if (!part)
385                 return;
386
387         blk_free_devt(part_devt(part));
388         rcu_assign_pointer(ptbl->part[partno], NULL);
389         rcu_assign_pointer(ptbl->last_lookup, NULL);
390         kobject_put(part->holder_dir);
391         device_del(part_to_dev(part));
392
393         call_rcu(&part->rcu_head, delete_partition_rcu_cb);
394 }
395
396 static ssize_t whole_disk_show(struct device *dev,
397                                struct device_attribute *attr, char *buf)
398 {
399         return 0;
400 }
401 static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH,
402                    whole_disk_show, NULL);
403
404 struct hd_struct *add_partition(struct gendisk *disk, int partno,
405                                 sector_t start, sector_t len, int flags,
406                                 struct partition_meta_info *info)
407 {
408         struct hd_struct *p;
409         dev_t devt = MKDEV(0, 0);
410         struct device *ddev = disk_to_dev(disk);
411         struct device *pdev;
412         struct disk_part_tbl *ptbl;
413         const char *dname;
414         int err;
415
416         err = disk_expand_part_tbl(disk, partno);
417         if (err)
418                 return ERR_PTR(err);
419         ptbl = disk->part_tbl;
420
421         if (ptbl->part[partno])
422                 return ERR_PTR(-EBUSY);
423
424         p = kzalloc(sizeof(*p), GFP_KERNEL);
425         if (!p)
426                 return ERR_PTR(-EBUSY);
427
428         if (!init_part_stats(p)) {
429                 err = -ENOMEM;
430                 goto out_free;
431         }
432         pdev = part_to_dev(p);
433
434         p->start_sect = start;
435         p->alignment_offset =
436                 queue_limit_alignment_offset(&disk->queue->limits, start);
437         p->discard_alignment =
438                 queue_limit_discard_alignment(&disk->queue->limits, start);
439         p->nr_sects = len;
440         p->partno = partno;
441         p->policy = get_disk_ro(disk);
442
443         if (info) {
444                 struct partition_meta_info *pinfo = alloc_part_info(disk);
445                 if (!pinfo)
446                         goto out_free_stats;
447                 memcpy(pinfo, info, sizeof(*info));
448                 p->info = pinfo;
449         }
450
451         dname = dev_name(ddev);
452         if (isdigit(dname[strlen(dname) - 1]))
453                 dev_set_name(pdev, "%sp%d", dname, partno);
454         else
455                 dev_set_name(pdev, "%s%d", dname, partno);
456
457         device_initialize(pdev);
458         pdev->class = &block_class;
459         pdev->type = &part_type;
460         pdev->parent = ddev;
461
462         err = blk_alloc_devt(p, &devt);
463         if (err)
464                 goto out_free_info;
465         pdev->devt = devt;
466
467         /* delay uevent until 'holders' subdir is created */
468         dev_set_uevent_suppress(pdev, 1);
469         err = device_add(pdev);
470         if (err)
471                 goto out_put;
472
473         err = -ENOMEM;
474         p->holder_dir = kobject_create_and_add("holders", &pdev->kobj);
475         if (!p->holder_dir)
476                 goto out_del;
477
478         dev_set_uevent_suppress(pdev, 0);
479         if (flags & ADDPART_FLAG_WHOLEDISK) {
480                 err = device_create_file(pdev, &dev_attr_whole_disk);
481                 if (err)
482                         goto out_del;
483         }
484
485         /* everything is up and running, commence */
486         rcu_assign_pointer(ptbl->part[partno], p);
487
488         /* suppress uevent if the disk supresses it */
489         if (!dev_get_uevent_suppress(ddev))
490                 kobject_uevent(&pdev->kobj, KOBJ_ADD);
491
492         return p;
493
494 out_free_info:
495         free_part_info(p);
496 out_free_stats:
497         free_part_stats(p);
498 out_free:
499         kfree(p);
500         return ERR_PTR(err);
501 out_del:
502         kobject_put(p->holder_dir);
503         device_del(pdev);
504 out_put:
505         put_device(pdev);
506         blk_free_devt(devt);
507         return ERR_PTR(err);
508 }
509
510 /* Not exported, helper to add_disk(). */
511 void register_disk(struct gendisk *disk)
512 {
513         struct device *ddev = disk_to_dev(disk);
514         struct block_device *bdev;
515         struct disk_part_iter piter;
516         struct hd_struct *part;
517         int err;
518
519         ddev->parent = disk->driverfs_dev;
520
521         dev_set_name(ddev, disk->disk_name);
522
523         /* delay uevents, until we scanned partition table */
524         dev_set_uevent_suppress(ddev, 1);
525
526         if (device_add(ddev))
527                 return;
528         if (!sysfs_deprecated) {
529                 err = sysfs_create_link(block_depr, &ddev->kobj,
530                                         kobject_name(&ddev->kobj));
531                 if (err) {
532                         device_del(ddev);
533                         return;
534                 }
535         }
536         disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
537         disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
538
539         /* No minors to use for partitions */
540         if (!disk_partitionable(disk))
541                 goto exit;
542
543         /* No such device (e.g., media were just removed) */
544         if (!get_capacity(disk))
545                 goto exit;
546
547         bdev = bdget_disk(disk, 0);
548         if (!bdev)
549                 goto exit;
550
551         bdev->bd_invalidated = 1;
552         err = blkdev_get(bdev, FMODE_READ);
553         if (err < 0)
554                 goto exit;
555         blkdev_put(bdev, FMODE_READ);
556
557 exit:
558         /* announce disk after possible partitions are created */
559         dev_set_uevent_suppress(ddev, 0);
560         kobject_uevent(&ddev->kobj, KOBJ_ADD);
561
562         /* announce possible partitions */
563         disk_part_iter_init(&piter, disk, 0);
564         while ((part = disk_part_iter_next(&piter)))
565                 kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
566         disk_part_iter_exit(&piter);
567 }
568
569 static bool disk_unlock_native_capacity(struct gendisk *disk)
570 {
571         const struct block_device_operations *bdops = disk->fops;
572
573         if (bdops->unlock_native_capacity &&
574             !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) {
575                 printk(KERN_CONT "enabling native capacity\n");
576                 bdops->unlock_native_capacity(disk);
577                 disk->flags |= GENHD_FL_NATIVE_CAPACITY;
578                 return true;
579         } else {
580                 printk(KERN_CONT "truncated\n");
581                 return false;
582         }
583 }
584
585 int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
586 {
587         struct parsed_partitions *state = NULL;
588         struct disk_part_iter piter;
589         struct hd_struct *part;
590         int p, highest, res;
591 rescan:
592         if (state && !IS_ERR(state)) {
593                 kfree(state);
594                 state = NULL;
595         }
596
597         if (bdev->bd_part_count)
598                 return -EBUSY;
599         res = invalidate_partition(disk, 0);
600         if (res)
601                 return res;
602
603         disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
604         while ((part = disk_part_iter_next(&piter)))
605                 delete_partition(disk, part->partno);
606         disk_part_iter_exit(&piter);
607
608         if (disk->fops->revalidate_disk)
609                 disk->fops->revalidate_disk(disk);
610         check_disk_size_change(disk, bdev);
611         bdev->bd_invalidated = 0;
612         if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
613                 return 0;
614         if (IS_ERR(state)) {
615                 /*
616                  * I/O error reading the partition table.  If any
617                  * partition code tried to read beyond EOD, retry
618                  * after unlocking native capacity.
619                  */
620                 if (PTR_ERR(state) == -ENOSPC) {
621                         printk(KERN_WARNING "%s: partition table beyond EOD, ",
622                                disk->disk_name);
623                         if (disk_unlock_native_capacity(disk))
624                                 goto rescan;
625                 }
626                 return -EIO;
627         }
628         /*
629          * If any partition code tried to read beyond EOD, try
630          * unlocking native capacity even if partition table is
631          * sucessfully read as we could be missing some partitions.
632          */
633         if (state->access_beyond_eod) {
634                 printk(KERN_WARNING
635                        "%s: partition table partially beyond EOD, ",
636                        disk->disk_name);
637                 if (disk_unlock_native_capacity(disk))
638                         goto rescan;
639         }
640
641         /* tell userspace that the media / partition table may have changed */
642         kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
643
644         /* Detect the highest partition number and preallocate
645          * disk->part_tbl.  This is an optimization and not strictly
646          * necessary.
647          */
648         for (p = 1, highest = 0; p < state->limit; p++)
649                 if (state->parts[p].size)
650                         highest = p;
651
652         disk_expand_part_tbl(disk, highest);
653
654         /* add partitions */
655         for (p = 1; p < state->limit; p++) {
656                 sector_t size, from;
657                 struct partition_meta_info *info = NULL;
658
659                 size = state->parts[p].size;
660                 if (!size)
661                         continue;
662
663                 from = state->parts[p].from;
664                 if (from >= get_capacity(disk)) {
665                         printk(KERN_WARNING
666                                "%s: p%d start %llu is beyond EOD, ",
667                                disk->disk_name, p, (unsigned long long) from);
668                         if (disk_unlock_native_capacity(disk))
669                                 goto rescan;
670                         continue;
671                 }
672
673                 if (from + size > get_capacity(disk)) {
674                         printk(KERN_WARNING
675                                "%s: p%d size %llu extends beyond EOD, ",
676                                disk->disk_name, p, (unsigned long long) size);
677
678                         if (disk_unlock_native_capacity(disk)) {
679                                 /* free state and restart */
680                                 goto rescan;
681                         } else {
682                                 /*
683                                  * we can not ignore partitions of broken tables
684                                  * created by for example camera firmware, but
685                                  * we limit them to the end of the disk to avoid
686                                  * creating invalid block devices
687                                  */
688                                 size = get_capacity(disk) - from;
689                         }
690                 }
691
692                 if (state->parts[p].has_info)
693                         info = &state->parts[p].info;
694                 part = add_partition(disk, p, from, size,
695                                      state->parts[p].flags,
696                                      &state->parts[p].info);
697                 if (IS_ERR(part)) {
698                         printk(KERN_ERR " %s: p%d could not be added: %ld\n",
699                                disk->disk_name, p, -PTR_ERR(part));
700                         continue;
701                 }
702 #ifdef CONFIG_BLK_DEV_MD
703                 if (state->parts[p].flags & ADDPART_FLAG_RAID)
704                         md_autodetect_dev(part_to_dev(part)->devt);
705 #endif
706         }
707         kfree(state);
708         return 0;
709 }
710
711 unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
712 {
713         struct address_space *mapping = bdev->bd_inode->i_mapping;
714         struct page *page;
715
716         page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
717                                  NULL);
718         if (!IS_ERR(page)) {
719                 if (PageError(page))
720                         goto fail;
721                 p->v = page;
722                 return (unsigned char *)page_address(page) +  ((n & ((1 << (PAGE_CACHE_SHIFT - 9)) - 1)) << 9);
723 fail:
724                 page_cache_release(page);
725         }
726         p->v = NULL;
727         return NULL;
728 }
729
730 EXPORT_SYMBOL(read_dev_sector);
731
732 void del_gendisk(struct gendisk *disk)
733 {
734         struct disk_part_iter piter;
735         struct hd_struct *part;
736
737         /* invalidate stuff */
738         disk_part_iter_init(&piter, disk,
739                              DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
740         while ((part = disk_part_iter_next(&piter))) {
741                 invalidate_partition(disk, part->partno);
742                 delete_partition(disk, part->partno);
743         }
744         disk_part_iter_exit(&piter);
745
746         invalidate_partition(disk, 0);
747         blk_free_devt(disk_to_dev(disk)->devt);
748         set_capacity(disk, 0);
749         disk->flags &= ~GENHD_FL_UP;
750         unlink_gendisk(disk);
751         part_stat_set_all(&disk->part0, 0);
752         disk->part0.stamp = 0;
753
754         kobject_put(disk->part0.holder_dir);
755         kobject_put(disk->slave_dir);
756         disk->driverfs_dev = NULL;
757         if (!sysfs_deprecated)
758                 sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
759         device_del(disk_to_dev(disk));
760 }