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