block/blk-sysfs.c

   1 /*
   2  * Functions related to sysfs handling
   3  */
   4 #include <linux/kernel.h>
   5 #include <linux/slab.h>
   6 #include <linux/module.h>
   7 #include <linux/bio.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/backing-dev.h>
  10 #include <linux/blktrace_api.h>
  11 #include <linux/blk-mq.h>
  12 #include <linux/blk-cgroup.h>
  13
  14 #include "blk.h"
  15 #include "blk-mq.h"
  16
  17 struct queue_sysfs_entry {
  18         struct attribute attr;
  19         ssize_t (*show)(struct request_queue *, char *);
  20         ssize_t (*store)(struct request_queue *, const char *, size_t);
  21 };
  22
  23 static ssize_t
  24 queue_var_show(unsigned long var, char *page)
  25 {
  26         return sprintf(page, "%lu\n", var);
  27 }
  28
  29 static ssize_t
  30 queue_var_store(unsigned long *var, const char *page, size_t count)
  31 {
  32         int err;
  33         unsigned long v;
  34
  35         err = kstrtoul(page, 10, &v);
  36         if (err || v > UINT_MAX)
  37                 return -EINVAL;
  38
  39         *var = v;
  40
  41         return count;
  42 }
  43
  44 static ssize_t queue_requests_show(struct request_queue *q, char *page)
  45 {
  46         return queue_var_show(q->nr_requests, (page));
  47 }
  48
  49 static ssize_t
  50 queue_requests_store(struct request_queue *q, const char *page, size_t count)
  51 {
  52         unsigned long nr;
  53         int ret, err;
  54
  55         if (!q->request_fn && !q->mq_ops)
  56                 return -EINVAL;
  57
  58         ret = queue_var_store(&nr, page, count);
  59         if (ret < 0)
  60                 return ret;
  61
  62         if (nr < BLKDEV_MIN_RQ)
  63                 nr = BLKDEV_MIN_RQ;
  64
  65         if (q->request_fn)
  66                 err = blk_update_nr_requests(q, nr);
  67         else
  68                 err = blk_mq_update_nr_requests(q, nr);
  69
  70         if (err)
  71                 return err;
  72
  73         return ret;
  74 }
  75
  76 static ssize_t queue_ra_show(struct request_queue *q, char *page)
  77 {
  78         unsigned long ra_kb = q->backing_dev_info.ra_pages <<
  79                                         (PAGE_SHIFT - 10);
  80
  81         return queue_var_show(ra_kb, (page));
  82 }
  83
  84 static ssize_t
  85 queue_ra_store(struct request_queue *q, const char *page, size_t count)
  86 {
  87         unsigned long ra_kb;
  88         ssize_t ret = queue_var_store(&ra_kb, page, count);
  89
  90         if (ret < 0)
  91                 return ret;
  92
  93         q->backing_dev_info.ra_pages = ra_kb >> (PAGE_SHIFT - 10);
  94
  95         return ret;
  96 }
  97
  98 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
  99 {
 100         int max_sectors_kb = queue_max_sectors(q) >> 1;
 101
 102         return queue_var_show(max_sectors_kb, (page));
 103 }
 104
 105 static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
 106 {
 107         return queue_var_show(queue_max_segments(q), (page));
 108 }
 109
 110 static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
 111 {
 112         return queue_var_show(q->limits.max_integrity_segments, (page));
 113 }
 114
 115 static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
 116 {
 117         if (blk_queue_cluster(q))
 118                 return queue_var_show(queue_max_segment_size(q), (page));
 119
 120         return queue_var_show(PAGE_SIZE, (page));
 121 }
 122
 123 static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
 124 {
 125         return queue_var_show(queue_logical_block_size(q), page);
 126 }
 127
 128 static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
 129 {
 130         return queue_var_show(queue_physical_block_size(q), page);
 131 }
 132
 133 static ssize_t queue_chunk_sectors_show(struct request_queue *q, char *page)
 134 {
 135         return queue_var_show(q->limits.chunk_sectors, page);
 136 }
 137
 138 static ssize_t queue_io_min_show(struct request_queue *q, char *page)
 139 {
 140         return queue_var_show(queue_io_min(q), page);
 141 }
 142
 143 static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
 144 {
 145         return queue_var_show(queue_io_opt(q), page);
 146 }
 147
 148 static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
 149 {
 150         return queue_var_show(q->limits.discard_granularity, page);
 151 }
 152
 153 static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
 154 {
 155
 156         return sprintf(page, "%llu\n",
 157                 (unsigned long long)q->limits.max_hw_discard_sectors << 9);
 158 }
 159
 160 static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
 161 {
 162         return sprintf(page, "%llu\n",
 163                        (unsigned long long)q->limits.max_discard_sectors << 9);
 164 }
 165
 166 static ssize_t queue_discard_max_store(struct request_queue *q,
 167                                        const char *page, size_t count)
 168 {
 169         unsigned long max_discard;
 170         ssize_t ret = queue_var_store(&max_discard, page, count);
 171
 172         if (ret < 0)
 173                 return ret;
 174
 175         if (max_discard & (q->limits.discard_granularity - 1))
 176                 return -EINVAL;
 177
 178         max_discard >>= 9;
 179         if (max_discard > UINT_MAX)
 180                 return -EINVAL;
 181
 182         if (max_discard > q->limits.max_hw_discard_sectors)
 183                 max_discard = q->limits.max_hw_discard_sectors;
 184
 185         q->limits.max_discard_sectors = max_discard;
 186         return ret;
 187 }
 188
 189 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
 190 {
 191         return queue_var_show(queue_discard_zeroes_data(q), page);
 192 }
 193
 194 static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
 195 {
 196         return sprintf(page, "%llu\n",
 197                 (unsigned long long)q->limits.max_write_same_sectors << 9);
 198 }
 199
 200
 201 static ssize_t
 202 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
 203 {
 204         unsigned long max_sectors_kb,
 205                 max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
 206                         page_kb = 1 << (PAGE_SHIFT - 10);
 207         ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
 208
 209         if (ret < 0)
 210                 return ret;
 211
 212         max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
 213                                          q->limits.max_dev_sectors >> 1);
 214
 215         if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
 216                 return -EINVAL;
 217
 218         spin_lock_irq(q->queue_lock);
 219         q->limits.max_sectors = max_sectors_kb << 1;
 220         spin_unlock_irq(q->queue_lock);
 221
 222         return ret;
 223 }
 224
 225 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
 226 {
 227         int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;
 228
 229         return queue_var_show(max_hw_sectors_kb, (page));
 230 }
 231
 232 #define QUEUE_SYSFS_BIT_FNS(name, flag, neg)                            \
 233 static ssize_t                                                          \
 234 queue_show_##name(struct request_queue *q, char *page)                  \
 235 {                                                                       \
 236         int bit;                                                        \
 237         bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags);             \
 238         return queue_var_show(neg ? !bit : bit, page);                  \
 239 }                                                                       \
 240 static ssize_t                                                          \
 241 queue_store_##name(struct request_queue *q, const char *page, size_t count) \
 242 {                                                                       \
 243         unsigned long val;                                              \
 244         ssize_t ret;                                                    \
 245         ret = queue_var_store(&val, page, count);                       \
 246         if (ret < 0)                                                    \
 247                  return ret;                                            \
 248         if (neg)                                                        \
 249                 val = !val;                                             \
 250                                                                         \
 251         spin_lock_irq(q->queue_lock);                                   \
 252         if (val)                                                        \
 253                 queue_flag_set(QUEUE_FLAG_##flag, q);                   \
 254         else                                                            \
 255                 queue_flag_clear(QUEUE_FLAG_##flag, q);                 \
 256         spin_unlock_irq(q->queue_lock);                                 \
 257         return ret;                                                     \
 258 }
 259
 260 QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
 261 QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
 262 QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
 263 #undef QUEUE_SYSFS_BIT_FNS
 264
 265 static ssize_t queue_zoned_show(struct request_queue *q, char *page)
 266 {
 267         switch (blk_queue_zoned_model(q)) {
 268         case BLK_ZONED_HA:
 269                 return sprintf(page, "host-aware\n");
 270         case BLK_ZONED_HM:
 271                 return sprintf(page, "host-managed\n");
 272         default:
 273                 return sprintf(page, "none\n");
 274         }
 275 }
 276
 277 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 278 {
 279         return queue_var_show((blk_queue_nomerges(q) << 1) |
 280                                blk_queue_noxmerges(q), page);
 281 }
 282
 283 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
 284                                     size_t count)
 285 {
 286         unsigned long nm;
 287         ssize_t ret = queue_var_store(&nm, page, count);
 288
 289         if (ret < 0)
 290                 return ret;
 291
 292         spin_lock_irq(q->queue_lock);
 293         queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
 294         queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
 295         if (nm == 2)
 296                 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
 297         else if (nm)
 298                 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
 299         spin_unlock_irq(q->queue_lock);
 300
 301         return ret;
 302 }
 303
 304 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
 305 {
 306         bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
 307         bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);
 308
 309         return queue_var_show(set << force, page);
 310 }
 311
 312 static ssize_t
 313 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
 314 {
 315         ssize_t ret = -EINVAL;
 316 #ifdef CONFIG_SMP
 317         unsigned long val;
 318
 319         ret = queue_var_store(&val, page, count);
 320         if (ret < 0)
 321                 return ret;
 322
 323         spin_lock_irq(q->queue_lock);
 324         if (val == 2) {
 325                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
 326                 queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
 327         } else if (val == 1) {
 328                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
 329                 queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
 330         } else if (val == 0) {
 331                 queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
 332                 queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
 333         }
 334         spin_unlock_irq(q->queue_lock);
 335 #endif
 336         return ret;
 337 }
 338
 339 static ssize_t queue_poll_show(struct request_queue *q, char *page)
 340 {
 341         return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
 342 }
 343
 344 static ssize_t queue_poll_store(struct request_queue *q, const char *page,
 345                                 size_t count)
 346 {
 347         unsigned long poll_on;
 348         ssize_t ret;
 349
 350         if (!q->mq_ops || !q->mq_ops->poll)
 351                 return -EINVAL;
 352
 353         ret = queue_var_store(&poll_on, page, count);
 354         if (ret < 0)
 355                 return ret;
 356
 357         spin_lock_irq(q->queue_lock);
 358         if (poll_on)
 359                 queue_flag_set(QUEUE_FLAG_POLL, q);
 360         else
 361                 queue_flag_clear(QUEUE_FLAG_POLL, q);
 362         spin_unlock_irq(q->queue_lock);
 363
 364         return ret;
 365 }
 366
 367 static ssize_t queue_wc_show(struct request_queue *q, char *page)
 368 {
 369         if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
 370                 return sprintf(page, "write back\n");
 371
 372         return sprintf(page, "write through\n");
 373 }
 374
 375 static ssize_t queue_wc_store(struct request_queue *q, const char *page,
 376                               size_t count)
 377 {
 378         int set = -1;
 379
 380         if (!strncmp(page, "write back", 10))
 381                 set = 1;
 382         else if (!strncmp(page, "write through", 13) ||
 383                  !strncmp(page, "none", 4))
 384                 set = 0;
 385
 386         if (set == -1)
 387                 return -EINVAL;
 388
 389         spin_lock_irq(q->queue_lock);
 390         if (set)
 391                 queue_flag_set(QUEUE_FLAG_WC, q);
 392         else
 393                 queue_flag_clear(QUEUE_FLAG_WC, q);
 394         spin_unlock_irq(q->queue_lock);
 395
 396         return count;
 397 }
 398
 399 static ssize_t queue_dax_show(struct request_queue *q, char *page)
 400 {
 401         return queue_var_show(blk_queue_dax(q), page);
 402 }
 403
 404 static ssize_t print_stat(char *page, struct blk_rq_stat *stat, const char *pre)
 405 {
 406         return sprintf(page, "%s samples=%llu, mean=%lld, min=%lld, max=%lld\n",
 407                         pre, (long long) stat->nr_samples,
 408                         (long long) stat->mean, (long long) stat->min,
 409                         (long long) stat->max);
 410 }
 411
 412 static ssize_t queue_stats_show(struct request_queue *q, char *page)
 413 {
 414         struct blk_rq_stat stat[2];
 415         ssize_t ret;
 416
 417         blk_queue_stat_get(q, stat);
 418
 419         ret = print_stat(page, &stat[BLK_STAT_READ], "read :");
 420         ret += print_stat(page + ret, &stat[BLK_STAT_WRITE], "write:");
 421         return ret;
 422 }
 423
 424 static struct queue_sysfs_entry queue_requests_entry = {
 425         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 426         .show = queue_requests_show,
 427         .store = queue_requests_store,
 428 };
 429
 430 static struct queue_sysfs_entry queue_ra_entry = {
 431         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
 432         .show = queue_ra_show,
 433         .store = queue_ra_store,
 434 };
 435
 436 static struct queue_sysfs_entry queue_max_sectors_entry = {
 437         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
 438         .show = queue_max_sectors_show,
 439         .store = queue_max_sectors_store,
 440 };
 441
 442 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
 443         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
 444         .show = queue_max_hw_sectors_show,
 445 };
 446
 447 static struct queue_sysfs_entry queue_max_segments_entry = {
 448         .attr = {.name = "max_segments", .mode = S_IRUGO },
 449         .show = queue_max_segments_show,
 450 };
 451
 452 static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
 453         .attr = {.name = "max_integrity_segments", .mode = S_IRUGO },
 454         .show = queue_max_integrity_segments_show,
 455 };
 456
 457 static struct queue_sysfs_entry queue_max_segment_size_entry = {
 458         .attr = {.name = "max_segment_size", .mode = S_IRUGO },
 459         .show = queue_max_segment_size_show,
 460 };
 461
 462 static struct queue_sysfs_entry queue_iosched_entry = {
 463         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
 464         .show = elv_iosched_show,
 465         .store = elv_iosched_store,
 466 };
 467
 468 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 469         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
 470         .show = queue_logical_block_size_show,
 471 };
 472
 473 static struct queue_sysfs_entry queue_logical_block_size_entry = {
 474         .attr = {.name = "logical_block_size", .mode = S_IRUGO },
 475         .show = queue_logical_block_size_show,
 476 };
 477
 478 static struct queue_sysfs_entry queue_physical_block_size_entry = {
 479         .attr = {.name = "physical_block_size", .mode = S_IRUGO },
 480         .show = queue_physical_block_size_show,
 481 };
 482
 483 static struct queue_sysfs_entry queue_chunk_sectors_entry = {
 484         .attr = {.name = "chunk_sectors", .mode = S_IRUGO },
 485         .show = queue_chunk_sectors_show,
 486 };
 487
 488 static struct queue_sysfs_entry queue_io_min_entry = {
 489         .attr = {.name = "minimum_io_size", .mode = S_IRUGO },
 490         .show = queue_io_min_show,
 491 };
 492
 493 static struct queue_sysfs_entry queue_io_opt_entry = {
 494         .attr = {.name = "optimal_io_size", .mode = S_IRUGO },
 495         .show = queue_io_opt_show,
 496 };
 497
 498 static struct queue_sysfs_entry queue_discard_granularity_entry = {
 499         .attr = {.name = "discard_granularity", .mode = S_IRUGO },
 500         .show = queue_discard_granularity_show,
 501 };
 502
 503 static struct queue_sysfs_entry queue_discard_max_hw_entry = {
 504         .attr = {.name = "discard_max_hw_bytes", .mode = S_IRUGO },
 505         .show = queue_discard_max_hw_show,
 506 };
 507
 508 static struct queue_sysfs_entry queue_discard_max_entry = {
 509         .attr = {.name = "discard_max_bytes", .mode = S_IRUGO | S_IWUSR },
 510         .show = queue_discard_max_show,
 511         .store = queue_discard_max_store,
 512 };
 513
 514 static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
 515         .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
 516         .show = queue_discard_zeroes_data_show,
 517 };
 518
 519 static struct queue_sysfs_entry queue_write_same_max_entry = {
 520         .attr = {.name = "write_same_max_bytes", .mode = S_IRUGO },
 521         .show = queue_write_same_max_show,
 522 };
 523
 524 static struct queue_sysfs_entry queue_nonrot_entry = {
 525         .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
 526         .show = queue_show_nonrot,
 527         .store = queue_store_nonrot,
 528 };
 529
 530 static struct queue_sysfs_entry queue_zoned_entry = {
 531         .attr = {.name = "zoned", .mode = S_IRUGO },
 532         .show = queue_zoned_show,
 533 };
 534
 535 static struct queue_sysfs_entry queue_nomerges_entry = {
 536         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
 537         .show = queue_nomerges_show,
 538         .store = queue_nomerges_store,
 539 };
 540
 541 static struct queue_sysfs_entry queue_rq_affinity_entry = {
 542         .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
 543         .show = queue_rq_affinity_show,
 544         .store = queue_rq_affinity_store,
 545 };
 546
 547 static struct queue_sysfs_entry queue_iostats_entry = {
 548         .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
 549         .show = queue_show_iostats,
 550         .store = queue_store_iostats,
 551 };
 552
 553 static struct queue_sysfs_entry queue_random_entry = {
 554         .attr = {.name = "add_random", .mode = S_IRUGO | S_IWUSR },
 555         .show = queue_show_random,
 556         .store = queue_store_random,
 557 };
 558
 559 static struct queue_sysfs_entry queue_poll_entry = {
 560         .attr = {.name = "io_poll", .mode = S_IRUGO | S_IWUSR },
 561         .show = queue_poll_show,
 562         .store = queue_poll_store,
 563 };
 564
 565 static struct queue_sysfs_entry queue_wc_entry = {
 566         .attr = {.name = "write_cache", .mode = S_IRUGO | S_IWUSR },
 567         .show = queue_wc_show,
 568         .store = queue_wc_store,
 569 };
 570
 571 static struct queue_sysfs_entry queue_dax_entry = {
 572         .attr = {.name = "dax", .mode = S_IRUGO },
 573         .show = queue_dax_show,
 574 };
 575
 576 static struct queue_sysfs_entry queue_stats_entry = {
 577         .attr = {.name = "stats", .mode = S_IRUGO },
 578         .show = queue_stats_show,
 579 };
 580
 581 static struct attribute *default_attrs[] = {
 582         &queue_requests_entry.attr,
 583         &queue_ra_entry.attr,
 584         &queue_max_hw_sectors_entry.attr,
 585         &queue_max_sectors_entry.attr,
 586         &queue_max_segments_entry.attr,
 587         &queue_max_integrity_segments_entry.attr,
 588         &queue_max_segment_size_entry.attr,
 589         &queue_iosched_entry.attr,
 590         &queue_hw_sector_size_entry.attr,
 591         &queue_logical_block_size_entry.attr,
 592         &queue_physical_block_size_entry.attr,
 593         &queue_chunk_sectors_entry.attr,
 594         &queue_io_min_entry.attr,
 595         &queue_io_opt_entry.attr,
 596         &queue_discard_granularity_entry.attr,
 597         &queue_discard_max_entry.attr,
 598         &queue_discard_max_hw_entry.attr,
 599         &queue_discard_zeroes_data_entry.attr,
 600         &queue_write_same_max_entry.attr,
 601         &queue_nonrot_entry.attr,
 602         &queue_zoned_entry.attr,
 603         &queue_nomerges_entry.attr,
 604         &queue_rq_affinity_entry.attr,
 605         &queue_iostats_entry.attr,
 606         &queue_random_entry.attr,
 607         &queue_poll_entry.attr,
 608         &queue_wc_entry.attr,
 609         &queue_dax_entry.attr,
 610         &queue_stats_entry.attr,
 611         NULL,
 612 };
 613
 614 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
 615
 616 static ssize_t
 617 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 618 {
 619         struct queue_sysfs_entry *entry = to_queue(attr);
 620         struct request_queue *q =
 621                 container_of(kobj, struct request_queue, kobj);
 622         ssize_t res;
 623
 624         if (!entry->show)
 625                 return -EIO;
 626         mutex_lock(&q->sysfs_lock);
 627         if (blk_queue_dying(q)) {
 628                 mutex_unlock(&q->sysfs_lock);
 629                 return -ENOENT;
 630         }
 631         res = entry->show(q, page);
 632         mutex_unlock(&q->sysfs_lock);
 633         return res;
 634 }
 635
 636 static ssize_t
 637 queue_attr_store(struct kobject *kobj, struct attribute *attr,
 638                     const char *page, size_t length)
 639 {
 640         struct queue_sysfs_entry *entry = to_queue(attr);
 641         struct request_queue *q;
 642         ssize_t res;
 643
 644         if (!entry->store)
 645                 return -EIO;
 646
 647         q = container_of(kobj, struct request_queue, kobj);
 648         mutex_lock(&q->sysfs_lock);
 649         if (blk_queue_dying(q)) {
 650                 mutex_unlock(&q->sysfs_lock);
 651                 return -ENOENT;
 652         }
 653         res = entry->store(q, page, length);
 654         mutex_unlock(&q->sysfs_lock);
 655         return res;
 656 }
 657
 658 static void blk_free_queue_rcu(struct rcu_head *rcu_head)
 659 {
 660         struct request_queue *q = container_of(rcu_head, struct request_queue,
 661                                                rcu_head);
 662         kmem_cache_free(blk_requestq_cachep, q);
 663 }
 664
 665 /**
 666  * blk_release_queue: - release a &struct request_queue when it is no longer needed
 667  * @kobj:    the kobj belonging to the request queue to be released
 668  *
 669  * Description:
 670  *     blk_release_queue is the pair to blk_init_queue() or
 671  *     blk_queue_make_request().  It should be called when a request queue is
 672  *     being released; typically when a block device is being de-registered.
 673  *     Currently, its primary task it to free all the &struct request
 674  *     structures that were allocated to the queue and the queue itself.
 675  *
 676  * Note:
 677  *     The low level driver must have finished any outstanding requests first
 678  *     via blk_cleanup_queue().
 679  **/
 680 static void blk_release_queue(struct kobject *kobj)
 681 {
 682         struct request_queue *q =
 683                 container_of(kobj, struct request_queue, kobj);
 684
 685         bdi_exit(&q->backing_dev_info);
 686         blkcg_exit_queue(q);
 687
 688         if (q->elevator) {
 689                 spin_lock_irq(q->queue_lock);
 690                 ioc_clear_queue(q);
 691                 spin_unlock_irq(q->queue_lock);
 692                 elevator_exit(q->elevator);
 693         }
 694
 695         blk_exit_rl(&q->root_rl);
 696
 697         if (q->queue_tags)
 698                 __blk_queue_free_tags(q);
 699
 700         if (!q->mq_ops)
 701                 blk_free_flush_queue(q->fq);
 702         else
 703                 blk_mq_release(q);
 704
 705         blk_trace_shutdown(q);
 706
 707         if (q->bio_split)
 708                 bioset_free(q->bio_split);
 709
 710         ida_simple_remove(&blk_queue_ida, q->id);
 711         call_rcu(&q->rcu_head, blk_free_queue_rcu);
 712 }
 713
 714 static const struct sysfs_ops queue_sysfs_ops = {
 715         .show   = queue_attr_show,
 716         .store  = queue_attr_store,
 717 };
 718
 719 struct kobj_type blk_queue_ktype = {
 720         .sysfs_ops      = &queue_sysfs_ops,
 721         .default_attrs  = default_attrs,
 722         .release        = blk_release_queue,
 723 };
 724
 725 int blk_register_queue(struct gendisk *disk)
 726 {
 727         int ret;
 728         struct device *dev = disk_to_dev(disk);
 729         struct request_queue *q = disk->queue;
 730
 731         if (WARN_ON(!q))
 732                 return -ENXIO;
 733
 734         /*
 735          * SCSI probing may synchronously create and destroy a lot of
 736          * request_queues for non-existent devices.  Shutting down a fully
 737          * functional queue takes measureable wallclock time as RCU grace
 738          * periods are involved.  To avoid excessive latency in these
 739          * cases, a request_queue starts out in a degraded mode which is
 740          * faster to shut down and is made fully functional here as
 741          * request_queues for non-existent devices never get registered.
 742          */
 743         if (!blk_queue_init_done(q)) {
 744                 queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
 745                 percpu_ref_switch_to_percpu(&q->q_usage_counter);
 746                 blk_queue_bypass_end(q);
 747         }
 748
 749         ret = blk_trace_init_sysfs(dev);
 750         if (ret)
 751                 return ret;
 752
 753         ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
 754         if (ret < 0) {
 755                 blk_trace_remove_sysfs(dev);
 756                 return ret;
 757         }
 758
 759         kobject_uevent(&q->kobj, KOBJ_ADD);
 760
 761         if (q->mq_ops)
 762                 blk_mq_register_dev(dev, q);
 763
 764         if (!q->request_fn)
 765                 return 0;
 766
 767         ret = elv_register_queue(q);
 768         if (ret) {
 769                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
 770                 kobject_del(&q->kobj);
 771                 blk_trace_remove_sysfs(dev);
 772                 kobject_put(&dev->kobj);
 773                 return ret;
 774         }
 775
 776         return 0;
 777 }
 778
 779 void blk_unregister_queue(struct gendisk *disk)
 780 {
 781         struct request_queue *q = disk->queue;
 782
 783         if (WARN_ON(!q))
 784                 return;
 785
 786         if (q->mq_ops)
 787                 blk_mq_unregister_dev(disk_to_dev(disk), q);
 788
 789         if (q->request_fn)
 790                 elv_unregister_queue(q);
 791
 792         kobject_uevent(&q->kobj, KOBJ_REMOVE);
 793         kobject_del(&q->kobj);
 794         blk_trace_remove_sysfs(disk_to_dev(disk));
 795         kobject_put(&disk_to_dev(disk)->kobj);
 796 }