linux/block/genhd.c
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   1/*
   2 *  gendisk handling
   3 */
   4
   5#include <linux/module.h>
   6#include <linux/fs.h>
   7#include <linux/genhd.h>
   8#include <linux/kdev_t.h>
   9#include <linux/kernel.h>
  10#include <linux/blkdev.h>
  11#include <linux/init.h>
  12#include <linux/spinlock.h>
  13#include <linux/proc_fs.h>
  14#include <linux/seq_file.h>
  15#include <linux/slab.h>
  16#include <linux/kmod.h>
  17#include <linux/kobj_map.h>
  18#include <linux/mutex.h>
  19#include <linux/idr.h>
  20#include <linux/log2.h>
  21#include <linux/pm_runtime.h>
  22
  23#include "blk.h"
  24
  25static DEFINE_MUTEX(block_class_lock);
  26struct kobject *block_depr;
  27
  28/* for extended dynamic devt allocation, currently only one major is used */
  29#define NR_EXT_DEVT             (1 << MINORBITS)
  30
  31/* For extended devt allocation.  ext_devt_mutex prevents look up
  32 * results from going away underneath its user.
  33 */
  34static DEFINE_MUTEX(ext_devt_mutex);
  35static DEFINE_IDR(ext_devt_idr);
  36
  37static struct device_type disk_type;
  38
  39static void disk_check_events(struct disk_events *ev,
  40                              unsigned int *clearing_ptr);
  41static void disk_alloc_events(struct gendisk *disk);
  42static void disk_add_events(struct gendisk *disk);
  43static void disk_del_events(struct gendisk *disk);
  44static void disk_release_events(struct gendisk *disk);
  45
  46/**
  47 * disk_get_part - get partition
  48 * @disk: disk to look partition from
  49 * @partno: partition number
  50 *
  51 * Look for partition @partno from @disk.  If found, increment
  52 * reference count and return it.
  53 *
  54 * CONTEXT:
  55 * Don't care.
  56 *
  57 * RETURNS:
  58 * Pointer to the found partition on success, NULL if not found.
  59 */
  60struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
  61{
  62        struct hd_struct *part = NULL;
  63        struct disk_part_tbl *ptbl;
  64
  65        if (unlikely(partno < 0))
  66                return NULL;
  67
  68        rcu_read_lock();
  69
  70        ptbl = rcu_dereference(disk->part_tbl);
  71        if (likely(partno < ptbl->len)) {
  72                part = rcu_dereference(ptbl->part[partno]);
  73                if (part)
  74                        get_device(part_to_dev(part));
  75        }
  76
  77        rcu_read_unlock();
  78
  79        return part;
  80}
  81EXPORT_SYMBOL_GPL(disk_get_part);
  82
  83/**
  84 * disk_part_iter_init - initialize partition iterator
  85 * @piter: iterator to initialize
  86 * @disk: disk to iterate over
  87 * @flags: DISK_PITER_* flags
  88 *
  89 * Initialize @piter so that it iterates over partitions of @disk.
  90 *
  91 * CONTEXT:
  92 * Don't care.
  93 */
  94void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
  95                          unsigned int flags)
  96{
  97        struct disk_part_tbl *ptbl;
  98
  99        rcu_read_lock();
 100        ptbl = rcu_dereference(disk->part_tbl);
 101
 102        piter->disk = disk;
 103        piter->part = NULL;
 104
 105        if (flags & DISK_PITER_REVERSE)
 106                piter->idx = ptbl->len - 1;
 107        else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
 108                piter->idx = 0;
 109        else
 110                piter->idx = 1;
 111
 112        piter->flags = flags;
 113
 114        rcu_read_unlock();
 115}
 116EXPORT_SYMBOL_GPL(disk_part_iter_init);
 117
 118/**
 119 * disk_part_iter_next - proceed iterator to the next partition and return it
 120 * @piter: iterator of interest
 121 *
 122 * Proceed @piter to the next partition and return it.
 123 *
 124 * CONTEXT:
 125 * Don't care.
 126 */
 127struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
 128{
 129        struct disk_part_tbl *ptbl;
 130        int inc, end;
 131
 132        /* put the last partition */
 133        disk_put_part(piter->part);
 134        piter->part = NULL;
 135
 136        /* get part_tbl */
 137        rcu_read_lock();
 138        ptbl = rcu_dereference(piter->disk->part_tbl);
 139
 140        /* determine iteration parameters */
 141        if (piter->flags & DISK_PITER_REVERSE) {
 142                inc = -1;
 143                if (piter->flags & (DISK_PITER_INCL_PART0 |
 144                                    DISK_PITER_INCL_EMPTY_PART0))
 145                        end = -1;
 146                else
 147                        end = 0;
 148        } else {
 149                inc = 1;
 150                end = ptbl->len;
 151        }
 152
 153        /* iterate to the next partition */
 154        for (; piter->idx != end; piter->idx += inc) {
 155                struct hd_struct *part;
 156
 157                part = rcu_dereference(ptbl->part[piter->idx]);
 158                if (!part)
 159                        continue;
 160                if (!part_nr_sects_read(part) &&
 161                    !(piter->flags & DISK_PITER_INCL_EMPTY) &&
 162                    !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
 163                      piter->idx == 0))
 164                        continue;
 165
 166                get_device(part_to_dev(part));
 167                piter->part = part;
 168                piter->idx += inc;
 169                break;
 170        }
 171
 172        rcu_read_unlock();
 173
 174        return piter->part;
 175}
 176EXPORT_SYMBOL_GPL(disk_part_iter_next);
 177
 178/**
 179 * disk_part_iter_exit - finish up partition iteration
 180 * @piter: iter of interest
 181 *
 182 * Called when iteration is over.  Cleans up @piter.
 183 *
 184 * CONTEXT:
 185 * Don't care.
 186 */
 187void disk_part_iter_exit(struct disk_part_iter *piter)
 188{
 189        disk_put_part(piter->part);
 190        piter->part = NULL;
 191}
 192EXPORT_SYMBOL_GPL(disk_part_iter_exit);
 193
 194static inline int sector_in_part(struct hd_struct *part, sector_t sector)
 195{
 196        return part->start_sect <= sector &&
 197                sector < part->start_sect + part_nr_sects_read(part);
 198}
 199
 200/**
 201 * disk_map_sector_rcu - map sector to partition
 202 * @disk: gendisk of interest
 203 * @sector: sector to map
 204 *
 205 * Find out which partition @sector maps to on @disk.  This is
 206 * primarily used for stats accounting.
 207 *
 208 * CONTEXT:
 209 * RCU read locked.  The returned partition pointer is valid only
 210 * while preemption is disabled.
 211 *
 212 * RETURNS:
 213 * Found partition on success, part0 is returned if no partition matches
 214 */
 215struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
 216{
 217        struct disk_part_tbl *ptbl;
 218        struct hd_struct *part;
 219        int i;
 220
 221        ptbl = rcu_dereference(disk->part_tbl);
 222
 223        part = rcu_dereference(ptbl->last_lookup);
 224        if (part && sector_in_part(part, sector))
 225                return part;
 226
 227        for (i = 1; i < ptbl->len; i++) {
 228                part = rcu_dereference(ptbl->part[i]);
 229
 230                if (part && sector_in_part(part, sector)) {
 231                        rcu_assign_pointer(ptbl->last_lookup, part);
 232                        return part;
 233                }
 234        }
 235        return &disk->part0;
 236}
 237EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
 238
 239/*
 240 * Can be deleted altogether. Later.
 241 *
 242 */
 243static struct blk_major_name {
 244        struct blk_major_name *next;
 245        int major;
 246        char name[16];
 247} *major_names[BLKDEV_MAJOR_HASH_SIZE];
 248
 249/* index in the above - for now: assume no multimajor ranges */
 250static inline int major_to_index(unsigned major)
 251{
 252        return major % BLKDEV_MAJOR_HASH_SIZE;
 253}
 254
 255#ifdef CONFIG_PROC_FS
 256void blkdev_show(struct seq_file *seqf, off_t offset)
 257{
 258        struct blk_major_name *dp;
 259
 260        if (offset < BLKDEV_MAJOR_HASH_SIZE) {
 261                mutex_lock(&block_class_lock);
 262                for (dp = major_names[offset]; dp; dp = dp->next)
 263                        seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
 264                mutex_unlock(&block_class_lock);
 265        }
 266}
 267#endif /* CONFIG_PROC_FS */
 268
 269/**
 270 * register_blkdev - register a new block device
 271 *
 272 * @major: the requested major device number [1..255]. If @major=0, try to
 273 *         allocate any unused major number.
 274 * @name: the name of the new block device as a zero terminated string
 275 *
 276 * The @name must be unique within the system.
 277 *
 278 * The return value depends on the @major input parameter.
 279 *  - if a major device number was requested in range [1..255] then the
 280 *    function returns zero on success, or a negative error code
 281 *  - if any unused major number was requested with @major=0 parameter
 282 *    then the return value is the allocated major number in range
 283 *    [1..255] or a negative error code otherwise
 284 */
 285int register_blkdev(unsigned int major, const char *name)
 286{
 287        struct blk_major_name **n, *p;
 288        int index, ret = 0;
 289
 290        mutex_lock(&block_class_lock);
 291
 292        /* temporary */
 293        if (major == 0) {
 294                for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
 295                        if (major_names[index] == NULL)
 296                                break;
 297                }
 298
 299                if (index == 0) {
 300                        printk("register_blkdev: failed to get major for %s\n",
 301                               name);
 302                        ret = -EBUSY;
 303                        goto out;
 304                }
 305                major = index;
 306                ret = major;
 307        }
 308
 309        p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
 310        if (p == NULL) {
 311                ret = -ENOMEM;
 312                goto out;
 313        }
 314
 315        p->major = major;
 316        strlcpy(p->name, name, sizeof(p->name));
 317        p->next = NULL;
 318        index = major_to_index(major);
 319
 320        for (n = &major_names[index]; *n; n = &(*n)->next) {
 321                if ((*n)->major == major)
 322                        break;
 323        }
 324        if (!*n)
 325                *n = p;
 326        else
 327                ret = -EBUSY;
 328
 329        if (ret < 0) {
 330                printk("register_blkdev: cannot get major %d for %s\n",
 331                       major, name);
 332                kfree(p);
 333        }
 334out:
 335        mutex_unlock(&block_class_lock);
 336        return ret;
 337}
 338
 339EXPORT_SYMBOL(register_blkdev);
 340
 341void unregister_blkdev(unsigned int major, const char *name)
 342{
 343        struct blk_major_name **n;
 344        struct blk_major_name *p = NULL;
 345        int index = major_to_index(major);
 346
 347        mutex_lock(&block_class_lock);
 348        for (n = &major_names[index]; *n; n = &(*n)->next)
 349                if ((*n)->major == major)
 350                        break;
 351        if (!*n || strcmp((*n)->name, name)) {
 352                WARN_ON(1);
 353        } else {
 354                p = *n;
 355                *n = p->next;
 356        }
 357        mutex_unlock(&block_class_lock);
 358        kfree(p);
 359}
 360
 361EXPORT_SYMBOL(unregister_blkdev);
 362
 363static struct kobj_map *bdev_map;
 364
 365/**
 366 * blk_mangle_minor - scatter minor numbers apart
 367 * @minor: minor number to mangle
 368 *
 369 * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
 370 * is enabled.  Mangling twice gives the original value.
 371 *
 372 * RETURNS:
 373 * Mangled value.
 374 *
 375 * CONTEXT:
 376 * Don't care.
 377 */
 378static int blk_mangle_minor(int minor)
 379{
 380#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
 381        int i;
 382
 383        for (i = 0; i < MINORBITS / 2; i++) {
 384                int low = minor & (1 << i);
 385                int high = minor & (1 << (MINORBITS - 1 - i));
 386                int distance = MINORBITS - 1 - 2 * i;
 387
 388                minor ^= low | high;    /* clear both bits */
 389                low <<= distance;       /* swap the positions */
 390                high >>= distance;
 391                minor |= low | high;    /* and set */
 392        }
 393#endif
 394        return minor;
 395}
 396
 397/**
 398 * blk_alloc_devt - allocate a dev_t for a partition
 399 * @part: partition to allocate dev_t for
 400 * @devt: out parameter for resulting dev_t
 401 *
 402 * Allocate a dev_t for block device.
 403 *
 404 * RETURNS:
 405 * 0 on success, allocated dev_t is returned in *@devt.  -errno on
 406 * failure.
 407 *
 408 * CONTEXT:
 409 * Might sleep.
 410 */
 411int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
 412{
 413        struct gendisk *disk = part_to_disk(part);
 414        int idx;
 415
 416        /* in consecutive minor range? */
 417        if (part->partno < disk->minors) {
 418                *devt = MKDEV(disk->major, disk->first_minor + part->partno);
 419                return 0;
 420        }
 421
 422        /* allocate ext devt */
 423        mutex_lock(&ext_devt_mutex);
 424        idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_KERNEL);
 425        mutex_unlock(&ext_devt_mutex);
 426        if (idx < 0)
 427                return idx == -ENOSPC ? -EBUSY : idx;
 428
 429        *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
 430        return 0;
 431}
 432
 433/**
 434 * blk_free_devt - free a dev_t
 435 * @devt: dev_t to free
 436 *
 437 * Free @devt which was allocated using blk_alloc_devt().
 438 *
 439 * CONTEXT:
 440 * Might sleep.
 441 */
 442void blk_free_devt(dev_t devt)
 443{
 444        might_sleep();
 445
 446        if (devt == MKDEV(0, 0))
 447                return;
 448
 449        if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
 450                mutex_lock(&ext_devt_mutex);
 451                idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
 452                mutex_unlock(&ext_devt_mutex);
 453        }
 454}
 455
 456static char *bdevt_str(dev_t devt, char *buf)
 457{
 458        if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
 459                char tbuf[BDEVT_SIZE];
 460                snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
 461                snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
 462        } else
 463                snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
 464
 465        return buf;
 466}
 467
 468/*
 469 * Register device numbers dev..(dev+range-1)
 470 * range must be nonzero
 471 * The hash chain is sorted on range, so that subranges can override.
 472 */
 473void blk_register_region(dev_t devt, unsigned long range, struct module *module,
 474                         struct kobject *(*probe)(dev_t, int *, void *),
 475                         int (*lock)(dev_t, void *), void *data)
 476{
 477        kobj_map(bdev_map, devt, range, module, probe, lock, data);
 478}
 479
 480EXPORT_SYMBOL(blk_register_region);
 481
 482void blk_unregister_region(dev_t devt, unsigned long range)
 483{
 484        kobj_unmap(bdev_map, devt, range);
 485}
 486
 487EXPORT_SYMBOL(blk_unregister_region);
 488
 489static struct kobject *exact_match(dev_t devt, int *partno, void *data)
 490{
 491        struct gendisk *p = data;
 492
 493        return &disk_to_dev(p)->kobj;
 494}
 495
 496static int exact_lock(dev_t devt, void *data)
 497{
 498        struct gendisk *p = data;
 499
 500        if (!get_disk(p))
 501                return -1;
 502        return 0;
 503}
 504
 505static void register_disk(struct gendisk *disk)
 506{
 507        struct device *ddev = disk_to_dev(disk);
 508        struct block_device *bdev;
 509        struct disk_part_iter piter;
 510        struct hd_struct *part;
 511        int err;
 512
 513        ddev->parent = disk->driverfs_dev;
 514
 515        dev_set_name(ddev, "%s", disk->disk_name);
 516
 517        /* delay uevents, until we scanned partition table */
 518        dev_set_uevent_suppress(ddev, 1);
 519
 520        if (device_add(ddev))
 521                return;
 522        if (!sysfs_deprecated) {
 523                err = sysfs_create_link(block_depr, &ddev->kobj,
 524                                        kobject_name(&ddev->kobj));
 525                if (err) {
 526                        device_del(ddev);
 527                        return;
 528                }
 529        }
 530
 531        /*
 532         * avoid probable deadlock caused by allocating memory with
 533         * GFP_KERNEL in runtime_resume callback of its all ancestor
 534         * devices
 535         */
 536        pm_runtime_set_memalloc_noio(ddev, true);
 537
 538        disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
 539        disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
 540
 541        /* No minors to use for partitions */
 542        if (!disk_part_scan_enabled(disk))
 543                goto exit;
 544
 545        /* No such device (e.g., media were just removed) */
 546        if (!get_capacity(disk))
 547                goto exit;
 548
 549        bdev = bdget_disk(disk, 0);
 550        if (!bdev)
 551                goto exit;
 552
 553        bdev->bd_invalidated = 1;
 554        err = blkdev_get(bdev, FMODE_READ, NULL);
 555        if (err < 0)
 556                goto exit;
 557        blkdev_put(bdev, FMODE_READ);
 558
 559exit:
 560        /* announce disk after possible partitions are created */
 561        dev_set_uevent_suppress(ddev, 0);
 562        kobject_uevent(&ddev->kobj, KOBJ_ADD);
 563
 564        /* announce possible partitions */
 565        disk_part_iter_init(&piter, disk, 0);
 566        while ((part = disk_part_iter_next(&piter)))
 567                kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
 568        disk_part_iter_exit(&piter);
 569}
 570
 571/**
 572 * add_disk - add partitioning information to kernel list
 573 * @disk: per-device partitioning information
 574 *
 575 * This function registers the partitioning information in @disk
 576 * with the kernel.
 577 *
 578 * FIXME: error handling
 579 */
 580void add_disk(struct gendisk *disk)
 581{
 582        struct backing_dev_info *bdi;
 583        dev_t devt;
 584        int retval;
 585
 586        /* minors == 0 indicates to use ext devt from part0 and should
 587         * be accompanied with EXT_DEVT flag.  Make sure all
 588         * parameters make sense.
 589         */
 590        WARN_ON(disk->minors && !(disk->major || disk->first_minor));
 591        WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
 592
 593        disk->flags |= GENHD_FL_UP;
 594
 595        retval = blk_alloc_devt(&disk->part0, &devt);
 596        if (retval) {
 597                WARN_ON(1);
 598                return;
 599        }
 600        disk_to_dev(disk)->devt = devt;
 601
 602        /* ->major and ->first_minor aren't supposed to be
 603         * dereferenced from here on, but set them just in case.
 604         */
 605        disk->major = MAJOR(devt);
 606        disk->first_minor = MINOR(devt);
 607
 608        disk_alloc_events(disk);
 609
 610        /* Register BDI before referencing it from bdev */
 611        bdi = &disk->queue->backing_dev_info;
 612        bdi_register_dev(bdi, disk_devt(disk));
 613
 614        blk_register_region(disk_devt(disk), disk->minors, NULL,
 615                            exact_match, exact_lock, disk);
 616        register_disk(disk);
 617        blk_register_queue(disk);
 618
 619        /*
 620         * Take an extra ref on queue which will be put on disk_release()
 621         * so that it sticks around as long as @disk is there.
 622         */
 623        WARN_ON_ONCE(!blk_get_queue(disk->queue));
 624
 625        retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
 626                                   "bdi");
 627        WARN_ON(retval);
 628
 629        disk_add_events(disk);
 630}
 631EXPORT_SYMBOL(add_disk);
 632
 633void del_gendisk(struct gendisk *disk)
 634{
 635        struct disk_part_iter piter;
 636        struct hd_struct *part;
 637
 638        disk_del_events(disk);
 639
 640        /* invalidate stuff */
 641        disk_part_iter_init(&piter, disk,
 642                             DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
 643        while ((part = disk_part_iter_next(&piter))) {
 644                invalidate_partition(disk, part->partno);
 645                delete_partition(disk, part->partno);
 646        }
 647        disk_part_iter_exit(&piter);
 648
 649        invalidate_partition(disk, 0);
 650        set_capacity(disk, 0);
 651        disk->flags &= ~GENHD_FL_UP;
 652
 653        sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
 654        bdi_unregister(&disk->queue->backing_dev_info);
 655        blk_unregister_queue(disk);
 656        blk_unregister_region(disk_devt(disk), disk->minors);
 657
 658        part_stat_set_all(&disk->part0, 0);
 659        disk->part0.stamp = 0;
 660
 661        kobject_put(disk->part0.holder_dir);
 662        kobject_put(disk->slave_dir);
 663        disk->driverfs_dev = NULL;
 664        if (!sysfs_deprecated)
 665                sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
 666        pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
 667        device_del(disk_to_dev(disk));
 668        blk_free_devt(disk_to_dev(disk)->devt);
 669}
 670EXPORT_SYMBOL(del_gendisk);
 671
 672/**
 673 * get_gendisk - get partitioning information for a given device
 674 * @devt: device to get partitioning information for
 675 * @partno: returned partition index
 676 *
 677 * This function gets the structure containing partitioning
 678 * information for the given device @devt.
 679 */
 680struct gendisk *get_gendisk(dev_t devt, int *partno)
 681{
 682        struct gendisk *disk = NULL;
 683
 684        if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
 685                struct kobject *kobj;
 686
 687                kobj = kobj_lookup(bdev_map, devt, partno);
 688                if (kobj)
 689                        disk = dev_to_disk(kobj_to_dev(kobj));
 690        } else {
 691                struct hd_struct *part;
 692
 693                mutex_lock(&ext_devt_mutex);
 694                part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
 695                if (part && get_disk(part_to_disk(part))) {
 696                        *partno = part->partno;
 697                        disk = part_to_disk(part);
 698                }
 699                mutex_unlock(&ext_devt_mutex);
 700        }
 701
 702        return disk;
 703}
 704EXPORT_SYMBOL(get_gendisk);
 705
 706/**
 707 * bdget_disk - do bdget() by gendisk and partition number
 708 * @disk: gendisk of interest
 709 * @partno: partition number
 710 *
 711 * Find partition @partno from @disk, do bdget() on it.
 712 *
 713 * CONTEXT:
 714 * Don't care.
 715 *
 716 * RETURNS:
 717 * Resulting block_device on success, NULL on failure.
 718 */
 719struct block_device *bdget_disk(struct gendisk *disk, int partno)
 720{
 721        struct hd_struct *part;
 722        struct block_device *bdev = NULL;
 723
 724        part = disk_get_part(disk, partno);
 725        if (part)
 726                bdev = bdget(part_devt(part));
 727        disk_put_part(part);
 728
 729        return bdev;
 730}
 731EXPORT_SYMBOL(bdget_disk);
 732
 733/*
 734 * print a full list of all partitions - intended for places where the root
 735 * filesystem can't be mounted and thus to give the victim some idea of what
 736 * went wrong
 737 */
 738void __init printk_all_partitions(void)
 739{
 740        struct class_dev_iter iter;
 741        struct device *dev;
 742
 743        class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
 744        while ((dev = class_dev_iter_next(&iter))) {
 745                struct gendisk *disk = dev_to_disk(dev);
 746                struct disk_part_iter piter;
 747                struct hd_struct *part;
 748                char name_buf[BDEVNAME_SIZE];
 749                char devt_buf[BDEVT_SIZE];
 750
 751                /*
 752                 * Don't show empty devices or things that have been
 753                 * suppressed
 754                 */
 755                if (get_capacity(disk) == 0 ||
 756                    (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
 757                        continue;
 758
 759                /*
 760                 * Note, unlike /proc/partitions, I am showing the
 761                 * numbers in hex - the same format as the root=
 762                 * option takes.
 763                 */
 764                disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
 765                while ((part = disk_part_iter_next(&piter))) {
 766                        bool is_part0 = part == &disk->part0;
 767
 768                        printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
 769                               bdevt_str(part_devt(part), devt_buf),
 770                               (unsigned long long)part_nr_sects_read(part) >> 1
 771                               , disk_name(disk, part->partno, name_buf),
 772                               part->info ? part->info->uuid : "");
 773                        if (is_part0) {
 774                                if (disk->driverfs_dev != NULL &&
 775                                    disk->driverfs_dev->driver != NULL)
 776                                        printk(" driver: %s\n",
 777                                              disk->driverfs_dev->driver->name);
 778                                else
 779                                        printk(" (driver?)\n");
 780                        } else
 781                                printk("\n");
 782                }
 783                disk_part_iter_exit(&piter);
 784        }
 785        class_dev_iter_exit(&iter);
 786}
 787
 788#ifdef CONFIG_PROC_FS
 789/* iterator */
 790static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
 791{
 792        loff_t skip = *pos;
 793        struct class_dev_iter *iter;
 794        struct device *dev;
 795
 796        iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 797        if (!iter)
 798                return ERR_PTR(-ENOMEM);
 799
 800        seqf->private = iter;
 801        class_dev_iter_init(iter, &block_class, NULL, &disk_type);
 802        do {
 803                dev = class_dev_iter_next(iter);
 804                if (!dev)
 805                        return NULL;
 806        } while (skip--);
 807
 808        return dev_to_disk(dev);
 809}
 810
 811static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
 812{
 813        struct device *dev;
 814
 815        (*pos)++;
 816        dev = class_dev_iter_next(seqf->private);
 817        if (dev)
 818                return dev_to_disk(dev);
 819
 820        return NULL;
 821}
 822
 823static void disk_seqf_stop(struct seq_file *seqf, void *v)
 824{
 825        struct class_dev_iter *iter = seqf->private;
 826
 827        /* stop is called even after start failed :-( */
 828        if (iter) {
 829                class_dev_iter_exit(iter);
 830                kfree(iter);
 831        }
 832}
 833
 834static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
 835{
 836        void *p;
 837
 838        p = disk_seqf_start(seqf, pos);
 839        if (!IS_ERR_OR_NULL(p) && !*pos)
 840                seq_puts(seqf, "major minor  #blocks  name\n\n");
 841        return p;
 842}
 843
 844static int show_partition(struct seq_file *seqf, void *v)
 845{
 846        struct gendisk *sgp = v;
 847        struct disk_part_iter piter;
 848        struct hd_struct *part;
 849        char buf[BDEVNAME_SIZE];
 850
 851        /* Don't show non-partitionable removeable devices or empty devices */
 852        if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
 853                                   (sgp->flags & GENHD_FL_REMOVABLE)))
 854                return 0;
 855        if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
 856                return 0;
 857
 858        /* show the full disk and all non-0 size partitions of it */
 859        disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
 860        while ((part = disk_part_iter_next(&piter)))
 861                seq_printf(seqf, "%4d  %7d %10llu %s\n",
 862                           MAJOR(part_devt(part)), MINOR(part_devt(part)),
 863                           (unsigned long long)part_nr_sects_read(part) >> 1,
 864                           disk_name(sgp, part->partno, buf));
 865        disk_part_iter_exit(&piter);
 866
 867        return 0;
 868}
 869
 870static const struct seq_operations partitions_op = {
 871        .start  = show_partition_start,
 872        .next   = disk_seqf_next,
 873        .stop   = disk_seqf_stop,
 874        .show   = show_partition
 875};
 876
 877static int partitions_open(struct inode *inode, struct file *file)
 878{
 879        return seq_open(file, &partitions_op);
 880}
 881
 882static const struct file_operations proc_partitions_operations = {
 883        .open           = partitions_open,
 884        .read           = seq_read,
 885        .llseek         = seq_lseek,
 886        .release        = seq_release,
 887};
 888#endif
 889
 890
 891static struct kobject *base_probe(dev_t devt, int *partno, void *data)
 892{
 893        if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
 894                /* Make old-style 2.4 aliases work */
 895                request_module("block-major-%d", MAJOR(devt));
 896        return NULL;
 897}
 898
 899static int __init genhd_device_init(void)
 900{
 901        int error;
 902
 903        block_class.dev_kobj = sysfs_dev_block_kobj;
 904        error = class_register(&block_class);
 905        if (unlikely(error))
 906                return error;
 907        bdev_map = kobj_map_init(base_probe, &block_class_lock);
 908        blk_dev_init();
 909
 910        register_blkdev(BLOCK_EXT_MAJOR, "blkext");
 911
 912        /* create top-level block dir */
 913        if (!sysfs_deprecated)
 914                block_depr = kobject_create_and_add("block", NULL);
 915        return 0;
 916}
 917
 918subsys_initcall(genhd_device_init);
 919
 920static ssize_t disk_range_show(struct device *dev,
 921                               struct device_attribute *attr, char *buf)
 922{
 923        struct gendisk *disk = dev_to_disk(dev);
 924
 925        return sprintf(buf, "%d\n", disk->minors);
 926}
 927
 928static ssize_t disk_ext_range_show(struct device *dev,
 929                                   struct device_attribute *attr, char *buf)
 930{
 931        struct gendisk *disk = dev_to_disk(dev);
 932
 933        return sprintf(buf, "%d\n", disk_max_parts(disk));
 934}
 935
 936static ssize_t disk_removable_show(struct device *dev,
 937                                   struct device_attribute *attr, char *buf)
 938{
 939        struct gendisk *disk = dev_to_disk(dev);
 940
 941        return sprintf(buf, "%d\n",
 942                       (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
 943}
 944
 945static ssize_t disk_ro_show(struct device *dev,
 946                                   struct device_attribute *attr, char *buf)
 947{
 948        struct gendisk *disk = dev_to_disk(dev);
 949
 950        return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
 951}
 952
 953static ssize_t disk_capability_show(struct device *dev,
 954                                    struct device_attribute *attr, char *buf)
 955{
 956        struct gendisk *disk = dev_to_disk(dev);
 957
 958        return sprintf(buf, "%x\n", disk->flags);
 959}
 960
 961static ssize_t disk_alignment_offset_show(struct device *dev,
 962                                          struct device_attribute *attr,
 963                                          char *buf)
 964{
 965        struct gendisk *disk = dev_to_disk(dev);
 966
 967        return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
 968}
 969
 970static ssize_t disk_discard_alignment_show(struct device *dev,
 971                                           struct device_attribute *attr,
 972                                           char *buf)
 973{
 974        struct gendisk *disk = dev_to_disk(dev);
 975
 976        return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));
 977}
 978
 979static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
 980static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
 981static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
 982static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
 983static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
 984static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
 985static DEVICE_ATTR(discard_alignment, S_IRUGO, disk_discard_alignment_show,
 986                   NULL);
 987static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
 988static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
 989static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
 990#ifdef CONFIG_FAIL_MAKE_REQUEST
 991static struct device_attribute dev_attr_fail =
 992        __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
 993#endif
 994#ifdef CONFIG_FAIL_IO_TIMEOUT
 995static struct device_attribute dev_attr_fail_timeout =
 996        __ATTR(io-timeout-fail,  S_IRUGO|S_IWUSR, part_timeout_show,
 997                part_timeout_store);
 998#endif
 999
1000static struct attribute *disk_attrs[] = {
1001        &dev_attr_range.attr,
1002        &dev_attr_ext_range.attr,
1003        &dev_attr_removable.attr,
1004        &dev_attr_ro.attr,
1005        &dev_attr_size.attr,
1006        &dev_attr_alignment_offset.attr,
1007        &dev_attr_discard_alignment.attr,
1008        &dev_attr_capability.attr,
1009        &dev_attr_stat.attr,
1010        &dev_attr_inflight.attr,
1011#ifdef CONFIG_FAIL_MAKE_REQUEST
1012        &dev_attr_fail.attr,
1013#endif
1014#ifdef CONFIG_FAIL_IO_TIMEOUT
1015        &dev_attr_fail_timeout.attr,
1016#endif
1017        NULL
1018};
1019
1020static struct attribute_group disk_attr_group = {
1021        .attrs = disk_attrs,
1022};
1023
1024static const struct attribute_group *disk_attr_groups[] = {
1025        &disk_attr_group,
1026        NULL
1027};
1028
1029/**
1030 * disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
1031 * @disk: disk to replace part_tbl for
1032 * @new_ptbl: new part_tbl to install
1033 *
1034 * Replace disk->part_tbl with @new_ptbl in RCU-safe way.  The
1035 * original ptbl is freed using RCU callback.
1036 *
1037 * LOCKING:
1038 * Matching bd_mutx locked.
1039 */
1040static void disk_replace_part_tbl(struct gendisk *disk,
1041                                  struct disk_part_tbl *new_ptbl)
1042{
1043        struct disk_part_tbl *old_ptbl = disk->part_tbl;
1044
1045        rcu_assign_pointer(disk->part_tbl, new_ptbl);
1046
1047        if (old_ptbl) {
1048                rcu_assign_pointer(old_ptbl->last_lookup, NULL);
1049                kfree_rcu(old_ptbl, rcu_head);
1050        }
1051}
1052
1053/**
1054 * disk_expand_part_tbl - expand disk->part_tbl
1055 * @disk: disk to expand part_tbl for
1056 * @partno: expand such that this partno can fit in
1057 *
1058 * Expand disk->part_tbl such that @partno can fit in.  disk->part_tbl
1059 * uses RCU to allow unlocked dereferencing for stats and other stuff.
1060 *
1061 * LOCKING:
1062 * Matching bd_mutex locked, might sleep.
1063 *
1064 * RETURNS:
1065 * 0 on success, -errno on failure.
1066 */
1067int disk_expand_part_tbl(struct gendisk *disk, int partno)
1068{
1069        struct disk_part_tbl *old_ptbl = disk->part_tbl;
1070        struct disk_part_tbl *new_ptbl;
1071        int len = old_ptbl ? old_ptbl->len : 0;
1072        int target = partno + 1;
1073        size_t size;
1074        int i;
1075
1076        /* disk_max_parts() is zero during initialization, ignore if so */
1077        if (disk_max_parts(disk) && target > disk_max_parts(disk))
1078                return -EINVAL;
1079
1080        if (target <= len)
1081                return 0;
1082
1083        size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
1084        new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
1085        if (!new_ptbl)
1086                return -ENOMEM;
1087
1088        new_ptbl->len = target;
1089
1090        for (i = 0; i < len; i++)
1091                rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
1092
1093        disk_replace_part_tbl(disk, new_ptbl);
1094        return 0;
1095}
1096
1097static void disk_release(struct device *dev)
1098{
1099        struct gendisk *disk = dev_to_disk(dev);
1100
1101        disk_release_events(disk);
1102        kfree(disk->random);
1103        disk_replace_part_tbl(disk, NULL);
1104        free_part_stats(&disk->part0);
1105        free_part_info(&disk->part0);
1106        if (disk->queue)
1107                blk_put_queue(disk->queue);
1108        kfree(disk);
1109}
1110struct class block_class = {
1111        .name           = "block",
1112};
1113
1114static char *block_devnode(struct device *dev, umode_t *mode,
1115                           kuid_t *uid, kgid_t *gid)
1116{
1117        struct gendisk *disk = dev_to_disk(dev);
1118
1119        if (disk->devnode)
1120                return disk->devnode(disk, mode);
1121        return NULL;
1122}
1123
1124static struct device_type disk_type = {
1125        .name           = "disk",
1126        .groups         = disk_attr_groups,
1127        .release        = disk_release,
1128        .devnode        = block_devnode,
1129};
1130
1131#ifdef CONFIG_PROC_FS
1132/*
1133 * aggregate disk stat collector.  Uses the same stats that the sysfs
1134 * entries do, above, but makes them available through one seq_file.
1135 *
1136 * The output looks suspiciously like /proc/partitions with a bunch of
1137 * extra fields.
1138 */
1139static int diskstats_show(struct seq_file *seqf, void *v)
1140{
1141        struct gendisk *gp = v;
1142        struct disk_part_iter piter;
1143        struct hd_struct *hd;
1144        char buf[BDEVNAME_SIZE];
1145        int cpu;
1146
1147        /*
1148        if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
1149                seq_puts(seqf,  "major minor name"
1150                                "     rio rmerge rsect ruse wio wmerge "
1151                                "wsect wuse running use aveq"
1152                                "\n\n");
1153        */
1154
1155        disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
1156        while ((hd = disk_part_iter_next(&piter))) {
1157                cpu = part_stat_lock();
1158                part_round_stats(cpu, hd);
1159                part_stat_unlock();
1160                seq_printf(seqf, "%4d %7d %s %lu %lu %lu "
1161                           "%u %lu %lu %lu %u %u %u %u\n",
1162                           MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
1163                           disk_name(gp, hd->partno, buf),
1164                           part_stat_read(hd, ios[READ]),
1165                           part_stat_read(hd, merges[READ]),
1166                           part_stat_read(hd, sectors[READ]),
1167                           jiffies_to_msecs(part_stat_read(hd, ticks[READ])),
1168                           part_stat_read(hd, ios[WRITE]),
1169                           part_stat_read(hd, merges[WRITE]),
1170                           part_stat_read(hd, sectors[WRITE]),
1171                           jiffies_to_msecs(part_stat_read(hd, ticks[WRITE])),
1172                           part_in_flight(hd),
1173                           jiffies_to_msecs(part_stat_read(hd, io_ticks)),
1174                           jiffies_to_msecs(part_stat_read(hd, time_in_queue))
1175                        );
1176        }
1177        disk_part_iter_exit(&piter);
1178
1179        return 0;
1180}
1181
1182static const struct seq_operations diskstats_op = {
1183        .start  = disk_seqf_start,
1184        .next   = disk_seqf_next,
1185        .stop   = disk_seqf_stop,
1186        .show   = diskstats_show
1187};
1188
1189static int diskstats_open(struct inode *inode, struct file *file)
1190{
1191        return seq_open(file, &diskstats_op);
1192}
1193
1194static const struct file_operations proc_diskstats_operations = {
1195        .open           = diskstats_open,
1196        .read           = seq_read,
1197        .llseek         = seq_lseek,
1198        .release        = seq_release,
1199};
1200
1201static int __init proc_genhd_init(void)
1202{
1203        proc_create("diskstats", 0, NULL, &proc_diskstats_operations);
1204        proc_create("partitions", 0, NULL, &proc_partitions_operations);
1205        return 0;
1206}
1207module_init(proc_genhd_init);
1208#endif /* CONFIG_PROC_FS */
1209
1210dev_t blk_lookup_devt(const char *name, int partno)
1211{
1212        dev_t devt = MKDEV(0, 0);
1213        struct class_dev_iter iter;
1214        struct device *dev;
1215
1216        class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
1217        while ((dev = class_dev_iter_next(&iter))) {
1218                struct gendisk *disk = dev_to_disk(dev);
1219                struct hd_struct *part;
1220
1221                if (strcmp(dev_name(dev), name))
1222                        continue;
1223
1224                if (partno < disk->minors) {
1225                        /* We need to return the right devno, even
1226                         * if the partition doesn't exist yet.
1227                         */
1228                        devt = MKDEV(MAJOR(dev->devt),
1229                                     MINOR(dev->devt) + partno);
1230                        break;
1231                }
1232                part = disk_get_part(disk, partno);
1233                if (part) {
1234                        devt = part_devt(part);
1235                        disk_put_part(part);
1236                        break;
1237                }
1238                disk_put_part(part);
1239        }
1240        class_dev_iter_exit(&iter);
1241        return devt;
1242}
1243EXPORT_SYMBOL(blk_lookup_devt);
1244
1245struct gendisk *alloc_disk(int minors)
1246{
1247        return alloc_disk_node(minors, NUMA_NO_NODE);
1248}
1249EXPORT_SYMBOL(alloc_disk);
1250
1251struct gendisk *alloc_disk_node(int minors, int node_id)
1252{
1253        struct gendisk *disk;
1254
1255        disk = kmalloc_node(sizeof(struct gendisk),
1256                                GFP_KERNEL | __GFP_ZERO, node_id);
1257        if (disk) {
1258                if (!init_part_stats(&disk->part0)) {
1259                        kfree(disk);
1260                        return NULL;
1261                }
1262                disk->node_id = node_id;
1263                if (disk_expand_part_tbl(disk, 0)) {
1264                        free_part_stats(&disk->part0);
1265                        kfree(disk);
1266                        return NULL;
1267                }
1268                disk->part_tbl->part[0] = &disk->part0;
1269
1270                /*
1271                 * set_capacity() and get_capacity() currently don't use
1272                 * seqcounter to read/update the part0->nr_sects. Still init
1273                 * the counter as we can read the sectors in IO submission
1274                 * patch using seqence counters.
1275                 *
1276                 * TODO: Ideally set_capacity() and get_capacity() should be
1277                 * converted to make use of bd_mutex and sequence counters.
1278                 */
1279                seqcount_init(&disk->part0.nr_sects_seq);
1280                hd_ref_init(&disk->part0);
1281
1282                disk->minors = minors;
1283                rand_initialize_disk(disk);
1284                disk_to_dev(disk)->class = &block_class;
1285                disk_to_dev(disk)->type = &disk_type;
1286                device_initialize(disk_to_dev(disk));
1287        }
1288        return disk;
1289}
1290EXPORT_SYMBOL(alloc_disk_node);
1291
1292struct kobject *get_disk(struct gendisk *disk)
1293{
1294        struct module *owner;
1295        struct kobject *kobj;
1296
1297        if (!disk->fops)
1298                return NULL;
1299        owner = disk->fops->owner;
1300        if (owner && !try_module_get(owner))
1301                return NULL;
1302        kobj = kobject_get(&disk_to_dev(disk)->kobj);
1303        if (kobj == NULL) {
1304                module_put(owner);
1305                return NULL;
1306        }
1307        return kobj;
1308
1309}
1310
1311EXPORT_SYMBOL(get_disk);
1312
1313void put_disk(struct gendisk *disk)
1314{
1315        if (disk)
1316                kobject_put(&disk_to_dev(disk)->kobj);
1317}
1318
1319EXPORT_SYMBOL(put_disk);
1320
1321static void set_disk_ro_uevent(struct gendisk *gd, int ro)
1322{
1323        char event[] = "DISK_RO=1";
1324        char *envp[] = { event, NULL };
1325
1326        if (!ro)
1327                event[8] = '0';
1328        kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
1329}
1330
1331void set_device_ro(struct block_device *bdev, int flag)
1332{
1333        bdev->bd_part->policy = flag;
1334}
1335
1336EXPORT_SYMBOL(set_device_ro);
1337
1338void set_disk_ro(struct gendisk *disk, int flag)
1339{
1340        struct disk_part_iter piter;
1341        struct hd_struct *part;
1342
1343        if (disk->part0.policy != flag) {
1344                set_disk_ro_uevent(disk, flag);
1345                disk->part0.policy = flag;
1346        }
1347
1348        disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
1349        while ((part = disk_part_iter_next(&piter)))
1350                part->policy = flag;
1351        disk_part_iter_exit(&piter);
1352}
1353
1354EXPORT_SYMBOL(set_disk_ro);
1355
1356int bdev_read_only(struct block_device *bdev)
1357{
1358        if (!bdev)
1359                return 0;
1360        return bdev->bd_part->policy;
1361}
1362
1363EXPORT_SYMBOL(bdev_read_only);
1364
1365int invalidate_partition(struct gendisk *disk, int partno)
1366{
1367        int res = 0;
1368        struct block_device *bdev = bdget_disk(disk, partno);
1369        if (bdev) {
1370                fsync_bdev(bdev);
1371                res = __invalidate_device(bdev, true);
1372                bdput(bdev);
1373        }
1374        return res;
1375}
1376
1377EXPORT_SYMBOL(invalidate_partition);
1378
1379/*
1380 * Disk events - monitor disk events like media change and eject request.
1381 */
1382struct disk_events {
1383        struct list_head        node;           /* all disk_event's */
1384        struct gendisk          *disk;          /* the associated disk */
1385        spinlock_t              lock;
1386
1387        struct mutex            block_mutex;    /* protects blocking */
1388        int                     block;          /* event blocking depth */
1389        unsigned int            pending;        /* events already sent out */
1390        unsigned int            clearing;       /* events being cleared */
1391
1392        long                    poll_msecs;     /* interval, -1 for default */
1393        struct delayed_work     dwork;
1394};
1395
1396static const char *disk_events_strs[] = {
1397        [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "media_change",
1398        [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "eject_request",
1399};
1400
1401static char *disk_uevents[] = {
1402        [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "DISK_MEDIA_CHANGE=1",
1403        [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "DISK_EJECT_REQUEST=1",
1404};
1405
1406/* list of all disk_events */
1407static DEFINE_MUTEX(disk_events_mutex);
1408static LIST_HEAD(disk_events);
1409
1410/* disable in-kernel polling by default */
1411static unsigned long disk_events_dfl_poll_msecs = 0;
1412
1413static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
1414{
1415        struct disk_events *ev = disk->ev;
1416        long intv_msecs = 0;
1417
1418        /*
1419         * If device-specific poll interval is set, always use it.  If
1420         * the default is being used, poll iff there are events which
1421         * can't be monitored asynchronously.
1422         */
1423        if (ev->poll_msecs >= 0)
1424                intv_msecs = ev->poll_msecs;
1425        else if (disk->events & ~disk->async_events)
1426                intv_msecs = disk_events_dfl_poll_msecs;
1427
1428        return msecs_to_jiffies(intv_msecs);
1429}
1430
1431/**
1432 * disk_block_events - block and flush disk event checking
1433 * @disk: disk to block events for
1434 *
1435 * On return from this function, it is guaranteed that event checking
1436 * isn't in progress and won't happen until unblocked by
1437 * disk_unblock_events().  Events blocking is counted and the actual
1438 * unblocking happens after the matching number of unblocks are done.
1439 *
1440 * Note that this intentionally does not block event checking from
1441 * disk_clear_events().
1442 *
1443 * CONTEXT:
1444 * Might sleep.
1445 */
1446void disk_block_events(struct gendisk *disk)
1447{
1448        struct disk_events *ev = disk->ev;
1449        unsigned long flags;
1450        bool cancel;
1451
1452        if (!ev)
1453                return;
1454
1455        /*
1456         * Outer mutex ensures that the first blocker completes canceling
1457         * the event work before further blockers are allowed to finish.
1458         */
1459        mutex_lock(&ev->block_mutex);
1460
1461        spin_lock_irqsave(&ev->lock, flags);
1462        cancel = !ev->block++;
1463        spin_unlock_irqrestore(&ev->lock, flags);
1464
1465        if (cancel)
1466                cancel_delayed_work_sync(&disk->ev->dwork);
1467
1468        mutex_unlock(&ev->block_mutex);
1469}
1470
1471static void __disk_unblock_events(struct gendisk *disk, bool check_now)
1472{
1473        struct disk_events *ev = disk->ev;
1474        unsigned long intv;
1475        unsigned long flags;
1476
1477        spin_lock_irqsave(&ev->lock, flags);
1478
1479        if (WARN_ON_ONCE(ev->block <= 0))
1480                goto out_unlock;
1481
1482        if (--ev->block)
1483                goto out_unlock;
1484
1485        /*
1486         * Not exactly a latency critical operation, set poll timer
1487         * slack to 25% and kick event check.
1488         */
1489        intv = disk_events_poll_jiffies(disk);
1490        set_timer_slack(&ev->dwork.timer, intv / 4);
1491        if (check_now)
1492                queue_delayed_work(system_freezable_power_efficient_wq,
1493                                &ev->dwork, 0);
1494        else if (intv)
1495                queue_delayed_work(system_freezable_power_efficient_wq,
1496                                &ev->dwork, intv);
1497out_unlock:
1498        spin_unlock_irqrestore(&ev->lock, flags);
1499}
1500
1501/**
1502 * disk_unblock_events - unblock disk event checking
1503 * @disk: disk to unblock events for
1504 *
1505 * Undo disk_block_events().  When the block count reaches zero, it
1506 * starts events polling if configured.
1507 *
1508 * CONTEXT:
1509 * Don't care.  Safe to call from irq context.
1510 */
1511void disk_unblock_events(struct gendisk *disk)
1512{
1513        if (disk->ev)
1514                __disk_unblock_events(disk, false);
1515}
1516
1517/**
1518 * disk_flush_events - schedule immediate event checking and flushing
1519 * @disk: disk to check and flush events for
1520 * @mask: events to flush
1521 *
1522 * Schedule immediate event checking on @disk if not blocked.  Events in
1523 * @mask are scheduled to be cleared from the driver.  Note that this
1524 * doesn't clear the events from @disk->ev.
1525 *
1526 * CONTEXT:
1527 * If @mask is non-zero must be called with bdev->bd_mutex held.
1528 */
1529void disk_flush_events(struct gendisk *disk, unsigned int mask)
1530{
1531        struct disk_events *ev = disk->ev;
1532
1533        if (!ev)
1534                return;
1535
1536        spin_lock_irq(&ev->lock);
1537        ev->clearing |= mask;
1538        if (!ev->block)
1539                mod_delayed_work(system_freezable_power_efficient_wq,
1540                                &ev->dwork, 0);
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        unsigned int clearing = mask;
1561
1562        if (!ev) {
1563                /* for drivers still using the old ->media_changed method */
1564                if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
1565                    bdops->media_changed && bdops->media_changed(disk))
1566                        return DISK_EVENT_MEDIA_CHANGE;
1567                return 0;
1568        }
1569
1570        disk_block_events(disk);
1571
1572        /*
1573         * store the union of mask and ev->clearing on the stack so that the
1574         * race with disk_flush_events does not cause ambiguity (ev->clearing
1575         * can still be modified even if events are blocked).
1576         */
1577        spin_lock_irq(&ev->lock);
1578        clearing |= ev->clearing;
1579        ev->clearing = 0;
1580        spin_unlock_irq(&ev->lock);
1581
1582        disk_check_events(ev, &clearing);
1583        /*
1584         * if ev->clearing is not 0, the disk_flush_events got called in the
1585         * middle of this function, so we want to run the workfn without delay.
1586         */
1587        __disk_unblock_events(disk, ev->clearing ? true : false);
1588
1589        /* then, fetch and clear pending events */
1590        spin_lock_irq(&ev->lock);
1591        pending = ev->pending & mask;
1592        ev->pending &= ~mask;
1593        spin_unlock_irq(&ev->lock);
1594        WARN_ON_ONCE(clearing & mask);
1595
1596        return pending;
1597}
1598
1599/*
1600 * Separate this part out so that a different pointer for clearing_ptr can be
1601 * passed in for disk_clear_events.
1602 */
1603static void disk_events_workfn(struct work_struct *work)
1604{
1605        struct delayed_work *dwork = to_delayed_work(work);
1606        struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
1607
1608        disk_check_events(ev, &ev->clearing);
1609}
1610
1611static void disk_check_events(struct disk_events *ev,
1612                              unsigned int *clearing_ptr)
1613{
1614        struct gendisk *disk = ev->disk;
1615        char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
1616        unsigned int clearing = *clearing_ptr;
1617        unsigned int events;
1618        unsigned long intv;
1619        int nr_events = 0, i;
1620
1621        /* check events */
1622        events = disk->fops->check_events(disk, clearing);
1623
1624        /* accumulate pending events and schedule next poll if necessary */
1625        spin_lock_irq(&ev->lock);
1626
1627        events &= ~ev->pending;
1628        ev->pending |= events;
1629        *clearing_ptr &= ~clearing;
1630
1631        intv = disk_events_poll_jiffies(disk);
1632        if (!ev->block && intv)
1633                queue_delayed_work(system_freezable_power_efficient_wq,
1634                                &ev->dwork, intv);
1635
1636        spin_unlock_irq(&ev->lock);
1637
1638        /*
1639         * Tell userland about new events.  Only the events listed in
1640         * @disk->events are reported.  Unlisted events are processed the
1641         * same internally but never get reported to userland.
1642         */
1643        for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
1644                if (events & disk->events & (1 << i))
1645                        envp[nr_events++] = disk_uevents[i];
1646
1647        if (nr_events)
1648                kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
1649}
1650
1651/*
1652 * A disk events enabled device has the following sysfs nodes under
1653 * its /sys/block/X/ directory.
1654 *
1655 * events               : list of all supported events
1656 * events_async         : list of events which can be detected w/o polling
1657 * events_poll_msecs    : polling interval, 0: disable, -1: system default
1658 */
1659static ssize_t __disk_events_show(unsigned int events, char *buf)
1660{
1661        const char *delim = "";
1662        ssize_t pos = 0;
1663        int i;
1664
1665        for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
1666                if (events & (1 << i)) {
1667                        pos += sprintf(buf + pos, "%s%s",
1668                                       delim, disk_events_strs[i]);
1669                        delim = " ";
1670                }
1671        if (pos)
1672                pos += sprintf(buf + pos, "\n");
1673        return pos;
1674}
1675
1676static ssize_t disk_events_show(struct device *dev,
1677                                struct device_attribute *attr, char *buf)
1678{
1679        struct gendisk *disk = dev_to_disk(dev);
1680
1681        return __disk_events_show(disk->events, buf);
1682}
1683
1684static ssize_t disk_events_async_show(struct device *dev,
1685                                      struct device_attribute *attr, char *buf)
1686{
1687        struct gendisk *disk = dev_to_disk(dev);
1688
1689        return __disk_events_show(disk->async_events, buf);
1690}
1691
1692static ssize_t disk_events_poll_msecs_show(struct device *dev,
1693                                           struct device_attribute *attr,
1694                                           char *buf)
1695{
1696        struct gendisk *disk = dev_to_disk(dev);
1697
1698        return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
1699}
1700
1701static ssize_t disk_events_poll_msecs_store(struct device *dev,
1702                                            struct device_attribute *attr,
1703                                            const char *buf, size_t count)
1704{
1705        struct gendisk *disk = dev_to_disk(dev);
1706        long intv;
1707
1708        if (!count || !sscanf(buf, "%ld", &intv))
1709                return -EINVAL;
1710
1711        if (intv < 0 && intv != -1)
1712                return -EINVAL;
1713
1714        disk_block_events(disk);
1715        disk->ev->poll_msecs = intv;
1716        __disk_unblock_events(disk, true);
1717
1718        return count;
1719}
1720
1721static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
1722static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
1723static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
1724                         disk_events_poll_msecs_show,
1725                         disk_events_poll_msecs_store);
1726
1727static const struct attribute *disk_events_attrs[] = {
1728        &dev_attr_events.attr,
1729        &dev_attr_events_async.attr,
1730        &dev_attr_events_poll_msecs.attr,
1731        NULL,
1732};
1733
1734/*
1735 * The default polling interval can be specified by the kernel
1736 * parameter block.events_dfl_poll_msecs which defaults to 0
1737 * (disable).  This can also be modified runtime by writing to
1738 * /sys/module/block/events_dfl_poll_msecs.
1739 */
1740static int disk_events_set_dfl_poll_msecs(const char *val,
1741                                          const struct kernel_param *kp)
1742{
1743        struct disk_events *ev;
1744        int ret;
1745
1746        ret = param_set_ulong(val, kp);
1747        if (ret < 0)
1748                return ret;
1749
1750        mutex_lock(&disk_events_mutex);
1751
1752        list_for_each_entry(ev, &disk_events, node)
1753                disk_flush_events(ev->disk, 0);
1754
1755        mutex_unlock(&disk_events_mutex);
1756
1757        return 0;
1758}
1759
1760static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
1761        .set    = disk_events_set_dfl_poll_msecs,
1762        .get    = param_get_ulong,
1763};
1764
1765#undef MODULE_PARAM_PREFIX
1766#define MODULE_PARAM_PREFIX     "block."
1767
1768module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
1769                &disk_events_dfl_poll_msecs, 0644);
1770
1771/*
1772 * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
1773 */
1774static void disk_alloc_events(struct gendisk *disk)
1775{
1776        struct disk_events *ev;
1777
1778        if (!disk->fops->check_events)
1779                return;
1780
1781        ev = kzalloc(sizeof(*ev), GFP_KERNEL);
1782        if (!ev) {
1783                pr_warn("%s: failed to initialize events\n", disk->disk_name);
1784                return;
1785        }
1786
1787        INIT_LIST_HEAD(&ev->node);
1788        ev->disk = disk;
1789        spin_lock_init(&ev->lock);
1790        mutex_init(&ev->block_mutex);
1791        ev->block = 1;
1792        ev->poll_msecs = -1;
1793        INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
1794
1795        disk->ev = ev;
1796}
1797
1798static void disk_add_events(struct gendisk *disk)
1799{
1800        if (!disk->ev)
1801                return;
1802
1803        /* FIXME: error handling */
1804        if (sysfs_create_files(&disk_to_dev(disk)->kobj, disk_events_attrs) < 0)
1805                pr_warn("%s: failed to create sysfs files for events\n",
1806                        disk->disk_name);
1807
1808        mutex_lock(&disk_events_mutex);
1809        list_add_tail(&disk->ev->node, &disk_events);
1810        mutex_unlock(&disk_events_mutex);
1811
1812        /*
1813         * Block count is initialized to 1 and the following initial
1814         * unblock kicks it into action.
1815         */
1816        __disk_unblock_events(disk, true);
1817}
1818
1819static void disk_del_events(struct gendisk *disk)
1820{
1821        if (!disk->ev)
1822                return;
1823
1824        disk_block_events(disk);
1825
1826        mutex_lock(&disk_events_mutex);
1827        list_del_init(&disk->ev->node);
1828        mutex_unlock(&disk_events_mutex);
1829
1830        sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
1831}
1832
1833static void disk_release_events(struct gendisk *disk)
1834{
1835        /* the block count should be 1 from disk_del_events() */
1836        WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
1837        kfree(disk->ev);
1838}
1839
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