Root/block/partition-generic.c

1/*
2 * Code extracted from drivers/block/genhd.c
3 * Copyright (C) 1991-1998 Linus Torvalds
4 * Re-organised Feb 1998 Russell King
5 *
6 * We now have independent partition support from the
7 * block drivers, which allows all the partition code to
8 * be grouped in one location, and it to be mostly self
9 * contained.
10 */
11
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/fs.h>
15#include <linux/slab.h>
16#include <linux/kmod.h>
17#include <linux/ctype.h>
18#include <linux/genhd.h>
19#include <linux/blktrace_api.h>
20
21#include "partitions/check.h"
22
23#ifdef CONFIG_BLK_DEV_MD
24extern void md_autodetect_dev(dev_t dev);
25#endif
26 
27/*
28 * disk_name() is used by partition check code and the genhd driver.
29 * It formats the devicename of the indicated disk into
30 * the supplied buffer (of size at least 32), and returns
31 * a pointer to that same buffer (for convenience).
32 */
33
34char *disk_name(struct gendisk *hd, int partno, char *buf)
35{
36    if (!partno)
37        snprintf(buf, BDEVNAME_SIZE, "%s", hd->disk_name);
38    else if (isdigit(hd->disk_name[strlen(hd->disk_name)-1]))
39        snprintf(buf, BDEVNAME_SIZE, "%sp%d", hd->disk_name, partno);
40    else
41        snprintf(buf, BDEVNAME_SIZE, "%s%d", hd->disk_name, partno);
42
43    return buf;
44}
45
46const char *bdevname(struct block_device *bdev, char *buf)
47{
48    return disk_name(bdev->bd_disk, bdev->bd_part->partno, buf);
49}
50
51EXPORT_SYMBOL(bdevname);
52
53/*
54 * There's very little reason to use this, you should really
55 * have a struct block_device just about everywhere and use
56 * bdevname() instead.
57 */
58const char *__bdevname(dev_t dev, char *buffer)
59{
60    scnprintf(buffer, BDEVNAME_SIZE, "unknown-block(%u,%u)",
61                MAJOR(dev), MINOR(dev));
62    return buffer;
63}
64
65EXPORT_SYMBOL(__bdevname);
66
67static ssize_t part_partition_show(struct device *dev,
68                   struct device_attribute *attr, char *buf)
69{
70    struct hd_struct *p = dev_to_part(dev);
71
72    return sprintf(buf, "%d\n", p->partno);
73}
74
75static ssize_t part_start_show(struct device *dev,
76                   struct device_attribute *attr, char *buf)
77{
78    struct hd_struct *p = dev_to_part(dev);
79
80    return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect);
81}
82
83ssize_t part_size_show(struct device *dev,
84               struct device_attribute *attr, char *buf)
85{
86    struct hd_struct *p = dev_to_part(dev);
87    return sprintf(buf, "%llu\n",(unsigned long long)part_nr_sects_read(p));
88}
89
90static ssize_t part_ro_show(struct device *dev,
91                struct device_attribute *attr, char *buf)
92{
93    struct hd_struct *p = dev_to_part(dev);
94    return sprintf(buf, "%d\n", p->policy ? 1 : 0);
95}
96
97static ssize_t part_alignment_offset_show(struct device *dev,
98                      struct device_attribute *attr, char *buf)
99{
100    struct hd_struct *p = dev_to_part(dev);
101    return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset);
102}
103
104static ssize_t part_discard_alignment_show(struct device *dev,
105                       struct device_attribute *attr, char *buf)
106{
107    struct hd_struct *p = dev_to_part(dev);
108    return sprintf(buf, "%u\n", p->discard_alignment);
109}
110
111ssize_t part_stat_show(struct device *dev,
112               struct device_attribute *attr, char *buf)
113{
114    struct hd_struct *p = dev_to_part(dev);
115    int cpu;
116
117    cpu = part_stat_lock();
118    part_round_stats(cpu, p);
119    part_stat_unlock();
120    return sprintf(buf,
121        "%8lu %8lu %8llu %8u "
122        "%8lu %8lu %8llu %8u "
123        "%8u %8u %8u"
124        "\n",
125        part_stat_read(p, ios[READ]),
126        part_stat_read(p, merges[READ]),
127        (unsigned long long)part_stat_read(p, sectors[READ]),
128        jiffies_to_msecs(part_stat_read(p, ticks[READ])),
129        part_stat_read(p, ios[WRITE]),
130        part_stat_read(p, merges[WRITE]),
131        (unsigned long long)part_stat_read(p, sectors[WRITE]),
132        jiffies_to_msecs(part_stat_read(p, ticks[WRITE])),
133        part_in_flight(p),
134        jiffies_to_msecs(part_stat_read(p, io_ticks)),
135        jiffies_to_msecs(part_stat_read(p, time_in_queue)));
136}
137
138ssize_t part_inflight_show(struct device *dev,
139            struct device_attribute *attr, char *buf)
140{
141    struct hd_struct *p = dev_to_part(dev);
142
143    return sprintf(buf, "%8u %8u\n", atomic_read(&p->in_flight[0]),
144        atomic_read(&p->in_flight[1]));
145}
146
147#ifdef CONFIG_FAIL_MAKE_REQUEST
148ssize_t part_fail_show(struct device *dev,
149               struct device_attribute *attr, char *buf)
150{
151    struct hd_struct *p = dev_to_part(dev);
152
153    return sprintf(buf, "%d\n", p->make_it_fail);
154}
155
156ssize_t part_fail_store(struct device *dev,
157            struct device_attribute *attr,
158            const char *buf, size_t count)
159{
160    struct hd_struct *p = dev_to_part(dev);
161    int i;
162
163    if (count > 0 && sscanf(buf, "%d", &i) > 0)
164        p->make_it_fail = (i == 0) ? 0 : 1;
165
166    return count;
167}
168#endif
169
170static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL);
171static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL);
172static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
173static DEVICE_ATTR(ro, S_IRUGO, part_ro_show, NULL);
174static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL);
175static DEVICE_ATTR(discard_alignment, S_IRUGO, part_discard_alignment_show,
176           NULL);
177static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
178static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
179#ifdef CONFIG_FAIL_MAKE_REQUEST
180static struct device_attribute dev_attr_fail =
181    __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
182#endif
183
184static struct attribute *part_attrs[] = {
185    &dev_attr_partition.attr,
186    &dev_attr_start.attr,
187    &dev_attr_size.attr,
188    &dev_attr_ro.attr,
189    &dev_attr_alignment_offset.attr,
190    &dev_attr_discard_alignment.attr,
191    &dev_attr_stat.attr,
192    &dev_attr_inflight.attr,
193#ifdef CONFIG_FAIL_MAKE_REQUEST
194    &dev_attr_fail.attr,
195#endif
196    NULL
197};
198
199static struct attribute_group part_attr_group = {
200    .attrs = part_attrs,
201};
202
203static const struct attribute_group *part_attr_groups[] = {
204    &part_attr_group,
205#ifdef CONFIG_BLK_DEV_IO_TRACE
206    &blk_trace_attr_group,
207#endif
208    NULL
209};
210
211static void part_release(struct device *dev)
212{
213    struct hd_struct *p = dev_to_part(dev);
214    free_part_stats(p);
215    free_part_info(p);
216    kfree(p);
217}
218
219struct device_type part_type = {
220    .name = "partition",
221    .groups = part_attr_groups,
222    .release = part_release,
223};
224
225static void delete_partition_rcu_cb(struct rcu_head *head)
226{
227    struct hd_struct *part = container_of(head, struct hd_struct, rcu_head);
228
229    part->start_sect = 0;
230    part->nr_sects = 0;
231    part_stat_set_all(part, 0);
232    put_device(part_to_dev(part));
233}
234
235void __delete_partition(struct hd_struct *part)
236{
237    call_rcu(&part->rcu_head, delete_partition_rcu_cb);
238}
239
240void delete_partition(struct gendisk *disk, int partno)
241{
242    struct disk_part_tbl *ptbl = disk->part_tbl;
243    struct hd_struct *part;
244
245    if (partno >= ptbl->len)
246        return;
247
248    part = ptbl->part[partno];
249    if (!part)
250        return;
251
252    rcu_assign_pointer(ptbl->part[partno], NULL);
253    rcu_assign_pointer(ptbl->last_lookup, NULL);
254    kobject_put(part->holder_dir);
255    device_del(part_to_dev(part));
256    blk_free_devt(part_devt(part));
257
258    hd_struct_put(part);
259}
260
261static ssize_t whole_disk_show(struct device *dev,
262                   struct device_attribute *attr, char *buf)
263{
264    return 0;
265}
266static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH,
267           whole_disk_show, NULL);
268
269struct hd_struct *add_partition(struct gendisk *disk, int partno,
270                sector_t start, sector_t len, int flags,
271                struct partition_meta_info *info)
272{
273    struct hd_struct *p;
274    dev_t devt = MKDEV(0, 0);
275    struct device *ddev = disk_to_dev(disk);
276    struct device *pdev;
277    struct disk_part_tbl *ptbl;
278    const char *dname;
279    int err;
280
281    err = disk_expand_part_tbl(disk, partno);
282    if (err)
283        return ERR_PTR(err);
284    ptbl = disk->part_tbl;
285
286    if (ptbl->part[partno])
287        return ERR_PTR(-EBUSY);
288
289    p = kzalloc(sizeof(*p), GFP_KERNEL);
290    if (!p)
291        return ERR_PTR(-EBUSY);
292
293    if (!init_part_stats(p)) {
294        err = -ENOMEM;
295        goto out_free;
296    }
297
298    seqcount_init(&p->nr_sects_seq);
299    pdev = part_to_dev(p);
300
301    p->start_sect = start;
302    p->alignment_offset =
303        queue_limit_alignment_offset(&disk->queue->limits, start);
304    p->discard_alignment =
305        queue_limit_discard_alignment(&disk->queue->limits, start);
306    p->nr_sects = len;
307    p->partno = partno;
308    p->policy = get_disk_ro(disk);
309
310    if (info) {
311        struct partition_meta_info *pinfo = alloc_part_info(disk);
312        if (!pinfo)
313            goto out_free_stats;
314        memcpy(pinfo, info, sizeof(*info));
315        p->info = pinfo;
316    }
317
318    dname = dev_name(ddev);
319    if (isdigit(dname[strlen(dname) - 1]))
320        dev_set_name(pdev, "%sp%d", dname, partno);
321    else
322        dev_set_name(pdev, "%s%d", dname, partno);
323
324    device_initialize(pdev);
325    pdev->class = &block_class;
326    pdev->type = &part_type;
327    pdev->parent = ddev;
328
329    err = blk_alloc_devt(p, &devt);
330    if (err)
331        goto out_free_info;
332    pdev->devt = devt;
333
334    /* delay uevent until 'holders' subdir is created */
335    dev_set_uevent_suppress(pdev, 1);
336    err = device_add(pdev);
337    if (err)
338        goto out_put;
339
340    err = -ENOMEM;
341    p->holder_dir = kobject_create_and_add("holders", &pdev->kobj);
342    if (!p->holder_dir)
343        goto out_del;
344
345    dev_set_uevent_suppress(pdev, 0);
346    if (flags & ADDPART_FLAG_WHOLEDISK) {
347        err = device_create_file(pdev, &dev_attr_whole_disk);
348        if (err)
349            goto out_del;
350    }
351
352    /* everything is up and running, commence */
353    rcu_assign_pointer(ptbl->part[partno], p);
354
355    /* suppress uevent if the disk suppresses it */
356    if (!dev_get_uevent_suppress(ddev))
357        kobject_uevent(&pdev->kobj, KOBJ_ADD);
358
359    hd_ref_init(p);
360    return p;
361
362out_free_info:
363    free_part_info(p);
364out_free_stats:
365    free_part_stats(p);
366out_free:
367    kfree(p);
368    return ERR_PTR(err);
369out_del:
370    kobject_put(p->holder_dir);
371    device_del(pdev);
372out_put:
373    put_device(pdev);
374    blk_free_devt(devt);
375    return ERR_PTR(err);
376}
377
378static bool disk_unlock_native_capacity(struct gendisk *disk)
379{
380    const struct block_device_operations *bdops = disk->fops;
381
382    if (bdops->unlock_native_capacity &&
383        !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) {
384        printk(KERN_CONT "enabling native capacity\n");
385        bdops->unlock_native_capacity(disk);
386        disk->flags |= GENHD_FL_NATIVE_CAPACITY;
387        return true;
388    } else {
389        printk(KERN_CONT "truncated\n");
390        return false;
391    }
392}
393
394static int drop_partitions(struct gendisk *disk, struct block_device *bdev)
395{
396    struct disk_part_iter piter;
397    struct hd_struct *part;
398    int res;
399
400    if (bdev->bd_part_count)
401        return -EBUSY;
402    res = invalidate_partition(disk, 0);
403    if (res)
404        return res;
405
406    disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
407    while ((part = disk_part_iter_next(&piter)))
408        delete_partition(disk, part->partno);
409    disk_part_iter_exit(&piter);
410
411    return 0;
412}
413
414int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
415{
416    struct parsed_partitions *state = NULL;
417    struct hd_struct *part;
418    int p, highest, res;
419rescan:
420    if (state && !IS_ERR(state)) {
421        free_partitions(state);
422        state = NULL;
423    }
424
425    res = drop_partitions(disk, bdev);
426    if (res)
427        return res;
428
429    if (disk->fops->revalidate_disk)
430        disk->fops->revalidate_disk(disk);
431    check_disk_size_change(disk, bdev);
432    bdev->bd_invalidated = 0;
433    if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
434        return 0;
435    if (IS_ERR(state)) {
436        /*
437         * I/O error reading the partition table. If any
438         * partition code tried to read beyond EOD, retry
439         * after unlocking native capacity.
440         */
441        if (PTR_ERR(state) == -ENOSPC) {
442            printk(KERN_WARNING "%s: partition table beyond EOD, ",
443                   disk->disk_name);
444            if (disk_unlock_native_capacity(disk))
445                goto rescan;
446        }
447        return -EIO;
448    }
449    /*
450     * If any partition code tried to read beyond EOD, try
451     * unlocking native capacity even if partition table is
452     * successfully read as we could be missing some partitions.
453     */
454    if (state->access_beyond_eod) {
455        printk(KERN_WARNING
456               "%s: partition table partially beyond EOD, ",
457               disk->disk_name);
458        if (disk_unlock_native_capacity(disk))
459            goto rescan;
460    }
461
462    /* tell userspace that the media / partition table may have changed */
463    kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
464
465    /* Detect the highest partition number and preallocate
466     * disk->part_tbl. This is an optimization and not strictly
467     * necessary.
468     */
469    for (p = 1, highest = 0; p < state->limit; p++)
470        if (state->parts[p].size)
471            highest = p;
472
473    disk_expand_part_tbl(disk, highest);
474
475    /* add partitions */
476    for (p = 1; p < state->limit; p++) {
477        sector_t size, from;
478        struct partition_meta_info *info = NULL;
479
480        size = state->parts[p].size;
481        if (!size)
482            continue;
483
484        from = state->parts[p].from;
485        if (from >= get_capacity(disk)) {
486            printk(KERN_WARNING
487                   "%s: p%d start %llu is beyond EOD, ",
488                   disk->disk_name, p, (unsigned long long) from);
489            if (disk_unlock_native_capacity(disk))
490                goto rescan;
491            continue;
492        }
493
494        if (from + size > get_capacity(disk)) {
495            printk(KERN_WARNING
496                   "%s: p%d size %llu extends beyond EOD, ",
497                   disk->disk_name, p, (unsigned long long) size);
498
499            if (disk_unlock_native_capacity(disk)) {
500                /* free state and restart */
501                goto rescan;
502            } else {
503                /*
504                 * we can not ignore partitions of broken tables
505                 * created by for example camera firmware, but
506                 * we limit them to the end of the disk to avoid
507                 * creating invalid block devices
508                 */
509                size = get_capacity(disk) - from;
510            }
511        }
512
513        if (state->parts[p].has_info)
514            info = &state->parts[p].info;
515        part = add_partition(disk, p, from, size,
516                     state->parts[p].flags,
517                     &state->parts[p].info);
518        if (IS_ERR(part)) {
519            printk(KERN_ERR " %s: p%d could not be added: %ld\n",
520                   disk->disk_name, p, -PTR_ERR(part));
521            continue;
522        }
523#ifdef CONFIG_BLK_DEV_MD
524        if (state->parts[p].flags & ADDPART_FLAG_RAID)
525            md_autodetect_dev(part_to_dev(part)->devt);
526#endif
527    }
528    free_partitions(state);
529    return 0;
530}
531
532int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
533{
534    int res;
535
536    if (!bdev->bd_invalidated)
537        return 0;
538
539    res = drop_partitions(disk, bdev);
540    if (res)
541        return res;
542
543    set_capacity(disk, 0);
544    check_disk_size_change(disk, bdev);
545    bdev->bd_invalidated = 0;
546    /* tell userspace that the media / partition table may have changed */
547    kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
548
549    return 0;
550}
551
552unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
553{
554    struct address_space *mapping = bdev->bd_inode->i_mapping;
555    struct page *page;
556
557    page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
558                 NULL);
559    if (!IS_ERR(page)) {
560        if (PageError(page))
561            goto fail;
562        p->v = page;
563        return (unsigned char *)page_address(page) + ((n & ((1 << (PAGE_CACHE_SHIFT - 9)) - 1)) << 9);
564fail:
565        page_cache_release(page);
566    }
567    p->v = NULL;
568    return NULL;
569}
570
571EXPORT_SYMBOL(read_dev_sector);
572

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