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 #include "blk-wbt.h"
  17
  18 struct queue_sysfs_entry {
  19         struct attribute attr;
  20         ssize_t (*show)(struct request_queue *, char *);
  21         ssize_t (*store)(struct request_queue *, const char *, size_t);
  22 };
  23
  24 static ssize_t
  25 queue_var_show(unsigned long var, char *page)
  26 {
  27         return sprintf(page, "%lu\n", var);
  28 }
  29
  30 static ssize_t
  31 queue_var_store(unsigned long *var, const char *page, size_t count)
  32 {
  33         int err;
  34         unsigned long v;
  35
  36         err = kstrtoul(page, 10, &v);
  37         if (err || v > UINT_MAX)
  38                 return -EINVAL;
  39
  40         *var = v;
  41
  42         return count;
  43 }
  44
  45 static ssize_t queue_var_store64(u64 *var, const char *page)
  46 {
  47         int err;
  48         u64 v;
  49
  50         err = kstrtou64(page, 10, &v);
  51         if (err < 0)
  52                 return err;
  53
  54         *var = v;
  55         return 0;
  56 }
  57
  58 static ssize_t queue_requests_show(struct request_queue *q, char *page)
  59 {
  60         return queue_var_show(q->nr_requests, (page));
  61 }
  62
  63 static ssize_t
  64 queue_requests_store(struct request_queue *q, const char *page, size_t count)
  65 {
  66         unsigned long nr;
  67         int ret, err;
  68
  69         if (!q->request_fn && !q->mq_ops)
  70                 return -EINVAL;
  71
  72         ret = queue_var_store(&nr, page, count);
  73         if (ret < 0)
  74                 return ret;
  75
  76         if (nr < BLKDEV_MIN_RQ)
  77                 nr = BLKDEV_MIN_RQ;
  78
  79         if (q->request_fn)
  80                 err = blk_update_nr_requests(q, nr);
  81         else
  82                 err = blk_mq_update_nr_requests(q, nr);
  83
  84         if (err)
  85                 return err;
  86
  87         return ret;
  88 }
  89
  90 static ssize_t queue_ra_show(struct request_queue *q, char *page)
  91 {
  92         unsigned long ra_kb = q->backing_dev_info.ra_pages <<
  93                                         (PAGE_SHIFT - 10);
  94
  95         return queue_var_show(ra_kb, (page));
  96 }
  97
  98 static ssize_t
  99 queue_ra_store(struct request_queue *q, const char *page, size_t count)
 100 {
 101         unsigned long ra_kb;
 102         ssize_t ret = queue_var_store(&ra_kb, page, count);
 103
 104         if (ret < 0)
 105                 return ret;
 106
 107         q->backing_dev_info.ra_pages = ra_kb >> (PAGE_SHIFT - 10);
 108
 109         return ret;
 110 }
 111
 112 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
 113 {
 114         int max_sectors_kb = queue_max_sectors(q) >> 1;
 115
 116         return queue_var_show(max_sectors_kb, (page));
 117 }
 118
 119 static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
 120 {
 121         return queue_var_show(queue_max_segments(q), (page));
 122 }
 123
 124 static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
 125 {
 126         return queue_var_show(q->limits.max_integrity_segments, (page));
 127 }
 128
 129 static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
 130 {
 131         if (blk_queue_cluster(q))
 132                 return queue_var_show(queue_max_segment_size(q), (page));
 133
 134         return queue_var_show(PAGE_SIZE, (page));
 135 }
 136
 137 static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
 138 {
 139         return queue_var_show(queue_logical_block_size(q), page);
 140 }
 141
 142 static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
 143 {
 144         return queue_var_show(queue_physical_block_size(q), page);
 145 }
 146
 147 static ssize_t queue_chunk_sectors_show(struct request_queue *q, char *page)
 148 {
 149         return queue_var_show(q->limits.chunk_sectors, page);
 150 }
 151
 152 static ssize_t queue_io_min_show(struct request_queue *q, char *page)
 153 {
 154         return queue_var_show(queue_io_min(q), page);
 155 }
 156
 157 static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
 158 {
 159         return queue_var_show(queue_io_opt(q), page);
 160 }
 161
 162 static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
 163 {
 164         return queue_var_show(q->limits.discard_granularity, page);
 165 }
 166
 167 static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
 168 {
 169
 170         return sprintf(page, "%llu\n",
 171                 (unsigned long long)q->limits.max_hw_discard_sectors << 9);
 172 }
 173
 174 static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
 175 {
 176         return sprintf(page, "%llu\n",
 177                        (unsigned long long)q->limits.max_discard_sectors << 9);
 178 }
 179
 180 static ssize_t queue_discard_max_store(struct request_queue *q,
 181                                        const char *page, size_t count)
 182 {
 183         unsigned long max_discard;
 184         ssize_t ret = queue_var_store(&max_discard, page, count);
 185
 186         if (ret < 0)
 187                 return ret;
 188
 189         if (max_discard & (q->limits.discard_granularity - 1))
 190                 return -EINVAL;
 191
 192         max_discard >>= 9;
 193         if (max_discard > UINT_MAX)
 194                 return -EINVAL;
 195
 196         if (max_discard > q->limits.max_hw_discard_sectors)
 197                 max_discard = q->limits.max_hw_discard_sectors;
 198
 199         q->limits.max_discard_sectors = max_discard;
 200         return ret;
 201 }
 202
 203 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
 204 {
 205         return queue_var_show(queue_discard_zeroes_data(q), page);
 206 }
 207
 208 static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
 209 {
 210         return sprintf(page, "%llu\n",
 211                 (unsigned long long)q->limits.max_write_same_sectors << 9);
 212 }
 213
 214
 215 static ssize_t
 216 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
 217 {
 218         unsigned long max_sectors_kb,
 219                 max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
 220                         page_kb = 1 << (PAGE_SHIFT - 10);
 221         ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
 222
 223         if (ret < 0)
 224                 return ret;
 225
 226         max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
 227                                          q->limits.max_dev_sectors >> 1);
 228
 229         if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
 230                 return -EINVAL;
 231
 232         spin_lock_irq(q->queue_lock);
 233         q->limits.max_sectors = max_sectors_kb << 1;
 234         spin_unlock_irq(q->queue_lock);
 235
 236         return ret;
 237 }
 238
 239 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
 240 {
 241         int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;
 242
 243         return queue_var_show(max_hw_sectors_kb, (page));
 244 }
 245
 246 #define QUEUE_SYSFS_BIT_FNS(name, flag, neg)                            \
 247 static ssize_t                                                          \
 248 queue_show_##name(struct request_queue *q, char *page)                  \
 249 {                                                                       \
 250         int bit;                                                        \
 251         bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags);             \
 252         return queue_var_show(neg ? !bit : bit, page);                  \
 253 }                                                                       \
 254 static ssize_t                                                          \
 255 queue_store_##name(struct request_queue *q, const char *page, size_t count) \
 256 {                                                                       \
 257         unsigned long val;                                              \
 258         ssize_t ret;                                                    \
 259         ret = queue_var_store(&val, page, count);                       \
 260         if (ret < 0)                                                    \
 261                  return ret;                                            \
 262         if (neg)                                                        \
 263                 val = !val;                                             \
 264                                                                         \
 265         spin_lock_irq(q->queue_lock);                                   \
 266         if (val)                                                        \
 267                 queue_flag_set(QUEUE_FLAG_##flag, q);                   \
 268         else                                                            \
 269                 queue_flag_clear(QUEUE_FLAG_##flag, q);                 \
 270         spin_unlock_irq(q->queue_lock);                                 \
 271         return ret;                                                     \
 272 }
 273
 274 QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
 275 QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
 276 QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
 277 #undef QUEUE_SYSFS_BIT_FNS
 278
 279 static ssize_t queue_zoned_show(struct request_queue *q, char *page)
 280 {
 281         switch (blk_queue_zoned_model(q)) {
 282         case BLK_ZONED_HA:
 283                 return sprintf(page, "host-aware\n");
 284         case BLK_ZONED_HM:
 285                 return sprintf(page, "host-managed\n");
 286         default:
 287                 return sprintf(page, "none\n");
 288         }
 289 }
 290
 291 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 292 {
 293         return queue_var_show((blk_queue_nomerges(q) << 1) |
 294                                blk_queue_noxmerges(q), page);
 295 }
 296
 297 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
 298                                     size_t count)
 299 {
 300         unsigned long nm;
 301         ssize_t ret = queue_var_store(&nm, page, count);
 302
 303         if (ret < 0)
 304                 return ret;
 305
 306         spin_lock_irq(q->queue_lock);
 307         queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
 308         queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
 309         if (nm == 2)
 310                 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
 311         else if (nm)
 312                 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
 313         spin_unlock_irq(q->queue_lock);
 314
 315         return ret;
 316 }
 317
 318 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
 319 {
 320         bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
 321         bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);
 322
 323         return queue_var_show(set << force, page);
 324 }
 325
 326 static ssize_t
 327 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
 328 {
 329         ssize_t ret = -EINVAL;
 330 #ifdef CONFIG_SMP
 331         unsigned long val;
 332
 333         ret = queue_var_store(&val, page, count);
 334         if (ret < 0)
 335                 return ret;
 336
 337         spin_lock_irq(q->queue_lock);
 338         if (val == 2) {
 339                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
 340                 queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
 341         } else if (val == 1) {
 342                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
 343                 queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
 344         } else if (val == 0) {
 345                 queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
 346                 queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
 347         }
 348         spin_unlock_irq(q->queue_lock);
 349 #endif
 350         return ret;
 351 }
 352
 353 static ssize_t queue_poll_show(struct request_queue *q, char *page)
 354 {
 355         return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
 356 }
 357
 358 static ssize_t queue_poll_store(struct request_queue *q, const char *page,
 359                                 size_t count)
 360 {
 361         unsigned long poll_on;
 362         ssize_t ret;
 363
 364         if (!q->mq_ops || !q->mq_ops->poll)
 365                 return -EINVAL;
 366
 367         ret = queue_var_store(&poll_on, page, count);
 368         if (ret < 0)
 369                 return ret;
 370
 371         spin_lock_irq(q->queue_lock);
 372         if (poll_on)
 373                 queue_flag_set(QUEUE_FLAG_POLL, q);
 374         else
 375                 queue_flag_clear(QUEUE_FLAG_POLL, q);
 376         spin_unlock_irq(q->queue_lock);
 377
 378         return ret;
 379 }
 380
 381 static ssize_t queue_wb_lat_show(struct request_queue *q, char *page)
 382 {
 383         if (!q->rq_wb)
 384                 return -EINVAL;
 385
 386         return sprintf(page, "%llu\n", div_u64(q->rq_wb->min_lat_nsec, 1000));
 387 }
 388
 389 static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
 390                                   size_t count)
 391 {
 392         ssize_t ret;
 393         u64 val;
 394
 395         if (!q->rq_wb)
 396                 return -EINVAL;
 397
 398         ret = queue_var_store64(&val, page);
 399         if (ret < 0)
 400                 return ret;
 401
 402         q->rq_wb->min_lat_nsec = val * 1000ULL;
 403         wbt_update_limits(q->rq_wb);
 404         return count;
 405 }
 406
 407 static ssize_t queue_wc_show(struct request_queue *q, char *page)
 408 {
 409         if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
 410                 return sprintf(page, "write back\n");
 411
 412         return sprintf(page, "write through\n");
 413 }
 414
 415 static ssize_t queue_wc_store(struct request_queue *q, const char *page,
 416                               size_t count)
 417 {
 418         int set = -1;
 419
 420         if (!strncmp(page, "write back", 10))
 421                 set = 1;
 422         else if (!strncmp(page, "write through", 13) ||
 423                  !strncmp(page, "none", 4))
 424                 set = 0;
 425
 426         if (set == -1)
 427                 return -EINVAL;
 428
 429         spin_lock_irq(q->queue_lock);
 430         if (set)
 431                 queue_flag_set(QUEUE_FLAG_WC, q);
 432         else
 433                 queue_flag_clear(QUEUE_FLAG_WC, q);
 434         spin_unlock_irq(q->queue_lock);
 435
 436         return count;
 437 }
 438
 439 static ssize_t queue_dax_show(struct request_queue *q, char *page)
 440 {
 441         return queue_var_show(blk_queue_dax(q), page);
 442 }
 443
 444 static ssize_t print_stat(char *page, struct blk_rq_stat *stat, const char *pre)
 445 {
 446         return sprintf(page, "%s samples=%llu, mean=%lld, min=%lld, max=%lld\n",
 447                         pre, (long long) stat->nr_samples,
 448                         (long long) stat->mean, (long long) stat->min,
 449                         (long long) stat->max);
 450 }
 451
 452 static ssize_t queue_stats_show(struct request_queue *q, char *page)
 453 {
 454         struct blk_rq_stat stat[2];
 455         ssize_t ret;
 456
 457         blk_queue_stat_get(q, stat);
 458
 459         ret = print_stat(page, &stat[BLK_STAT_READ], "read :");
 460         ret += print_stat(page + ret, &stat[BLK_STAT_WRITE], "write:");
 461         return ret;
 462 }
 463
 464 static struct queue_sysfs_entry queue_requests_entry = {
 465         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 466         .show = queue_requests_show,
 467         .store = queue_requests_store,
 468 };
 469
 470 static struct queue_sysfs_entry queue_ra_entry = {
 471         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
 472         .show = queue_ra_show,
 473         .store = queue_ra_store,
 474 };
 475
 476 static struct queue_sysfs_entry queue_max_sectors_entry = {
 477         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
 478         .show = queue_max_sectors_show,
 479         .store = queue_max_sectors_store,
 480 };
 481
 482 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
 483         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
 484         .show = queue_max_hw_sectors_show,
 485 };
 486
 487 static struct queue_sysfs_entry queue_max_segments_entry = {
 488         .attr = {.name = "max_segments", .mode = S_IRUGO },
 489         .show = queue_max_segments_show,
 490 };
 491
 492 static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
 493         .attr = {.name = "max_integrity_segments", .mode = S_IRUGO },
 494         .show = queue_max_integrity_segments_show,
 495 };
 496
 497 static struct queue_sysfs_entry queue_max_segment_size_entry = {
 498         .attr = {.name = "max_segment_size", .mode = S_IRUGO },
 499         .show = queue_max_segment_size_show,
 500 };
 501
 502 static struct queue_sysfs_entry queue_iosched_entry = {
 503         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
 504         .show = elv_iosched_show,
 505         .store = elv_iosched_store,
 506 };
 507
 508 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 509         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
 510         .show = queue_logical_block_size_show,
 511 };
 512
 513 static struct queue_sysfs_entry queue_logical_block_size_entry = {
 514         .attr = {.name = "logical_block_size", .mode = S_IRUGO },
 515         .show = queue_logical_block_size_show,
 516 };
 517
 518 static struct queue_sysfs_entry queue_physical_block_size_entry = {
 519         .attr = {.name = "physical_block_size", .mode = S_IRUGO },
 520         .show = queue_physical_block_size_show,
 521 };
 522
 523 static struct queue_sysfs_entry queue_chunk_sectors_entry = {
 524         .attr = {.name = "chunk_sectors", .mode = S_IRUGO },
 525         .show = queue_chunk_sectors_show,
 526 };
 527
 528 static struct queue_sysfs_entry queue_io_min_entry = {
 529         .attr = {.name = "minimum_io_size", .mode = S_IRUGO },
 530         .show = queue_io_min_show,
 531 };
 532
 533 static struct queue_sysfs_entry queue_io_opt_entry = {
 534         .attr = {.name = "optimal_io_size", .mode = S_IRUGO },
 535         .show = queue_io_opt_show,
 536 };
 537
 538 static struct queue_sysfs_entry queue_discard_granularity_entry = {
 539         .attr = {.name = "discard_granularity", .mode = S_IRUGO },
 540         .show = queue_discard_granularity_show,
 541 };
 542
 543 static struct queue_sysfs_entry queue_discard_max_hw_entry = {
 544         .attr = {.name = "discard_max_hw_bytes", .mode = S_IRUGO },
 545         .show = queue_discard_max_hw_show,
 546 };
 547
 548 static struct queue_sysfs_entry queue_discard_max_entry = {
 549         .attr = {.name = "discard_max_bytes", .mode = S_IRUGO | S_IWUSR },
 550         .show = queue_discard_max_show,
 551         .store = queue_discard_max_store,
 552 };
 553
 554 static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
 555         .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
 556         .show = queue_discard_zeroes_data_show,
 557 };
 558
 559 static struct queue_sysfs_entry queue_write_same_max_entry = {
 560         .attr = {.name = "write_same_max_bytes", .mode = S_IRUGO },
 561         .show = queue_write_same_max_show,
 562 };
 563
 564 static struct queue_sysfs_entry queue_nonrot_entry = {
 565         .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
 566         .show = queue_show_nonrot,
 567         .store = queue_store_nonrot,
 568 };
 569
 570 static struct queue_sysfs_entry queue_zoned_entry = {
 571         .attr = {.name = "zoned", .mode = S_IRUGO },
 572         .show = queue_zoned_show,
 573 };
 574
 575 static struct queue_sysfs_entry queue_nomerges_entry = {
 576         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
 577         .show = queue_nomerges_show,
 578         .store = queue_nomerges_store,
 579 };
 580
 581 static struct queue_sysfs_entry queue_rq_affinity_entry = {
 582         .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
 583         .show = queue_rq_affinity_show,
 584         .store = queue_rq_affinity_store,
 585 };
 586
 587 static struct queue_sysfs_entry queue_iostats_entry = {
 588         .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
 589         .show = queue_show_iostats,
 590         .store = queue_store_iostats,
 591 };
 592
 593 static struct queue_sysfs_entry queue_random_entry = {
 594         .attr = {.name = "add_random", .mode = S_IRUGO | S_IWUSR },
 595         .show = queue_show_random,
 596         .store = queue_store_random,
 597 };
 598
 599 static struct queue_sysfs_entry queue_poll_entry = {
 600         .attr = {.name = "io_poll", .mode = S_IRUGO | S_IWUSR },
 601         .show = queue_poll_show,
 602         .store = queue_poll_store,
 603 };
 604
 605 static struct queue_sysfs_entry queue_wc_entry = {
 606         .attr = {.name = "write_cache", .mode = S_IRUGO | S_IWUSR },
 607         .show = queue_wc_show,
 608         .store = queue_wc_store,
 609 };
 610
 611 static struct queue_sysfs_entry queue_dax_entry = {
 612         .attr = {.name = "dax", .mode = S_IRUGO },
 613         .show = queue_dax_show,
 614 };
 615
 616 static struct queue_sysfs_entry queue_stats_entry = {
 617         .attr = {.name = "stats", .mode = S_IRUGO },
 618         .show = queue_stats_show,
 619 };
 620
 621 static struct queue_sysfs_entry queue_wb_lat_entry = {
 622         .attr = {.name = "wbt_lat_usec", .mode = S_IRUGO | S_IWUSR },
 623         .show = queue_wb_lat_show,
 624         .store = queue_wb_lat_store,
 625 };
 626
 627 static struct attribute *default_attrs[] = {
 628         &queue_requests_entry.attr,
 629         &queue_ra_entry.attr,
 630         &queue_max_hw_sectors_entry.attr,
 631         &queue_max_sectors_entry.attr,
 632         &queue_max_segments_entry.attr,
 633         &queue_max_integrity_segments_entry.attr,
 634         &queue_max_segment_size_entry.attr,
 635         &queue_iosched_entry.attr,
 636         &queue_hw_sector_size_entry.attr,
 637         &queue_logical_block_size_entry.attr,
 638         &queue_physical_block_size_entry.attr,
 639         &queue_chunk_sectors_entry.attr,
 640         &queue_io_min_entry.attr,
 641         &queue_io_opt_entry.attr,
 642         &queue_discard_granularity_entry.attr,
 643         &queue_discard_max_entry.attr,
 644         &queue_discard_max_hw_entry.attr,
 645         &queue_discard_zeroes_data_entry.attr,
 646         &queue_write_same_max_entry.attr,
 647         &queue_nonrot_entry.attr,
 648         &queue_zoned_entry.attr,
 649         &queue_nomerges_entry.attr,
 650         &queue_rq_affinity_entry.attr,
 651         &queue_iostats_entry.attr,
 652         &queue_random_entry.attr,
 653         &queue_poll_entry.attr,
 654         &queue_wc_entry.attr,
 655         &queue_dax_entry.attr,
 656         &queue_stats_entry.attr,
 657         &queue_wb_lat_entry.attr,
 658         NULL,
 659 };
 660
 661 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
 662
 663 static ssize_t
 664 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 665 {
 666         struct queue_sysfs_entry *entry = to_queue(attr);
 667         struct request_queue *q =
 668                 container_of(kobj, struct request_queue, kobj);
 669         ssize_t res;
 670
 671         if (!entry->show)
 672                 return -EIO;
 673         mutex_lock(&q->sysfs_lock);
 674         if (blk_queue_dying(q)) {
 675                 mutex_unlock(&q->sysfs_lock);
 676                 return -ENOENT;
 677         }
 678         res = entry->show(q, page);
 679         mutex_unlock(&q->sysfs_lock);
 680         return res;
 681 }
 682
 683 static ssize_t
 684 queue_attr_store(struct kobject *kobj, struct attribute *attr,
 685                     const char *page, size_t length)
 686 {
 687         struct queue_sysfs_entry *entry = to_queue(attr);
 688         struct request_queue *q;
 689         ssize_t res;
 690
 691         if (!entry->store)
 692                 return -EIO;
 693
 694         q = container_of(kobj, struct request_queue, kobj);
 695         mutex_lock(&q->sysfs_lock);
 696         if (blk_queue_dying(q)) {
 697                 mutex_unlock(&q->sysfs_lock);
 698                 return -ENOENT;
 699         }
 700         res = entry->store(q, page, length);
 701         mutex_unlock(&q->sysfs_lock);
 702         return res;
 703 }
 704
 705 static void blk_free_queue_rcu(struct rcu_head *rcu_head)
 706 {
 707         struct request_queue *q = container_of(rcu_head, struct request_queue,
 708                                                rcu_head);
 709         kmem_cache_free(blk_requestq_cachep, q);
 710 }
 711
 712 /**
 713  * blk_release_queue: - release a &struct request_queue when it is no longer needed
 714  * @kobj:    the kobj belonging to the request queue to be released
 715  *
 716  * Description:
 717  *     blk_release_queue is the pair to blk_init_queue() or
 718  *     blk_queue_make_request().  It should be called when a request queue is
 719  *     being released; typically when a block device is being de-registered.
 720  *     Currently, its primary task it to free all the &struct request
 721  *     structures that were allocated to the queue and the queue itself.
 722  *
 723  * Note:
 724  *     The low level driver must have finished any outstanding requests first
 725  *     via blk_cleanup_queue().
 726  **/
 727 static void blk_release_queue(struct kobject *kobj)
 728 {
 729         struct request_queue *q =
 730                 container_of(kobj, struct request_queue, kobj);
 731
 732         wbt_exit(q);
 733         bdi_exit(&q->backing_dev_info);
 734         blkcg_exit_queue(q);
 735
 736         if (q->elevator) {
 737                 spin_lock_irq(q->queue_lock);
 738                 ioc_clear_queue(q);
 739                 spin_unlock_irq(q->queue_lock);
 740                 elevator_exit(q->elevator);
 741         }
 742
 743         blk_exit_rl(&q->root_rl);
 744
 745         if (q->queue_tags)
 746                 __blk_queue_free_tags(q);
 747
 748         if (!q->mq_ops)
 749                 blk_free_flush_queue(q->fq);
 750         else
 751                 blk_mq_release(q);
 752
 753         blk_trace_shutdown(q);
 754
 755         if (q->bio_split)
 756                 bioset_free(q->bio_split);
 757
 758         ida_simple_remove(&blk_queue_ida, q->id);
 759         call_rcu(&q->rcu_head, blk_free_queue_rcu);
 760 }
 761
 762 static const struct sysfs_ops queue_sysfs_ops = {
 763         .show   = queue_attr_show,
 764         .store  = queue_attr_store,
 765 };
 766
 767 struct kobj_type blk_queue_ktype = {
 768         .sysfs_ops      = &queue_sysfs_ops,
 769         .default_attrs  = default_attrs,
 770         .release        = blk_release_queue,
 771 };
 772
 773 static void blk_wb_init(struct request_queue *q)
 774 {
 775 #ifndef CONFIG_BLK_WBT_MQ
 776         if (q->mq_ops)
 777                 return;
 778 #endif
 779 #ifndef CONFIG_BLK_WBT_SQ
 780         if (q->request_fn)
 781                 return;
 782 #endif
 783
 784         /*
 785          * If this fails, we don't get throttling
 786          */
 787         wbt_init(q);
 788 }
 789
 790 int blk_register_queue(struct gendisk *disk)
 791 {
 792         int ret;
 793         struct device *dev = disk_to_dev(disk);
 794         struct request_queue *q = disk->queue;
 795
 796         if (WARN_ON(!q))
 797                 return -ENXIO;
 798
 799         /*
 800          * SCSI probing may synchronously create and destroy a lot of
 801          * request_queues for non-existent devices.  Shutting down a fully
 802          * functional queue takes measureable wallclock time as RCU grace
 803          * periods are involved.  To avoid excessive latency in these
 804          * cases, a request_queue starts out in a degraded mode which is
 805          * faster to shut down and is made fully functional here as
 806          * request_queues for non-existent devices never get registered.
 807          */
 808         if (!blk_queue_init_done(q)) {
 809                 queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
 810                 percpu_ref_switch_to_percpu(&q->q_usage_counter);
 811                 blk_queue_bypass_end(q);
 812         }
 813
 814         ret = blk_trace_init_sysfs(dev);
 815         if (ret)
 816                 return ret;
 817
 818         ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
 819         if (ret < 0) {
 820                 blk_trace_remove_sysfs(dev);
 821                 return ret;
 822         }
 823
 824         kobject_uevent(&q->kobj, KOBJ_ADD);
 825
 826         if (q->mq_ops)
 827                 blk_mq_register_dev(dev, q);
 828
 829         blk_wb_init(q);
 830
 831         if (!q->request_fn)
 832                 return 0;
 833
 834         ret = elv_register_queue(q);
 835         if (ret) {
 836                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
 837                 kobject_del(&q->kobj);
 838                 blk_trace_remove_sysfs(dev);
 839                 kobject_put(&dev->kobj);
 840                 return ret;
 841         }
 842
 843         return 0;
 844 }
 845
 846 void blk_unregister_queue(struct gendisk *disk)
 847 {
 848         struct request_queue *q = disk->queue;
 849
 850         if (WARN_ON(!q))
 851                 return;
 852
 853         if (q->mq_ops)
 854                 blk_mq_unregister_dev(disk_to_dev(disk), q);
 855
 856         if (q->request_fn)
 857                 elv_unregister_queue(q);
 858
 859         kobject_uevent(&q->kobj, KOBJ_REMOVE);
 860         kobject_del(&q->kobj);
 861         blk_trace_remove_sysfs(disk_to_dev(disk));
 862         kobject_put(&disk_to_dev(disk)->kobj);
 863 }