1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics 5 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 6 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> 7 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> 8 * - July2000 9 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 10 */ 11 12 /* 13 * This handles all read/write requests to block devices 14 */ 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/bio.h> 18 #include <linux/blkdev.h> 19 #include <linux/blk-pm.h> 20 #include <linux/blk-integrity.h> 21 #include <linux/highmem.h> 22 #include <linux/mm.h> 23 #include <linux/pagemap.h> 24 #include <linux/kernel_stat.h> 25 #include <linux/string.h> 26 #include <linux/init.h> 27 #include <linux/completion.h> 28 #include <linux/slab.h> 29 #include <linux/swap.h> 30 #include <linux/writeback.h> 31 #include <linux/task_io_accounting_ops.h> 32 #include <linux/fault-inject.h> 33 #include <linux/list_sort.h> 34 #include <linux/delay.h> 35 #include <linux/ratelimit.h> 36 #include <linux/pm_runtime.h> 37 #include <linux/t10-pi.h> 38 #include <linux/debugfs.h> 39 #include <linux/bpf.h> 40 #include <linux/part_stat.h> 41 #include <linux/sched/sysctl.h> 42 #include <linux/blk-crypto.h> 43 44 #define CREATE_TRACE_POINTS 45 #include <trace/events/block.h> 46 47 #include "blk.h" 48 #include "blk-mq-sched.h" 49 #include "blk-pm.h" 50 #include "blk-cgroup.h" 51 #include "blk-throttle.h" 52 #include "blk-ioprio.h" 53 #include "error-injection.h" 54 55 struct dentry *blk_debugfs_root; 56 57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 60 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 61 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 62 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert); 63 64 static DEFINE_IDA(blk_queue_ida); 65 66 /* 67 * For queue allocation 68 */ 69 static struct kmem_cache *blk_requestq_cachep; 70 71 /* 72 * Controlling structure to kblockd 73 */ 74 static struct workqueue_struct *kblockd_workqueue; 75 76 /** 77 * blk_queue_flag_set - atomically set a queue flag 78 * @flag: flag to be set 79 * @q: request queue 80 */ 81 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 82 { 83 set_bit(flag, &q->queue_flags); 84 } 85 EXPORT_SYMBOL(blk_queue_flag_set); 86 87 /** 88 * blk_queue_flag_clear - atomically clear a queue flag 89 * @flag: flag to be cleared 90 * @q: request queue 91 */ 92 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 93 { 94 clear_bit(flag, &q->queue_flags); 95 } 96 EXPORT_SYMBOL(blk_queue_flag_clear); 97 98 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name 99 static const char *const blk_op_name[] = { 100 REQ_OP_NAME(READ), 101 REQ_OP_NAME(WRITE), 102 REQ_OP_NAME(FLUSH), 103 REQ_OP_NAME(DISCARD), 104 REQ_OP_NAME(SECURE_ERASE), 105 REQ_OP_NAME(ZONE_RESET), 106 REQ_OP_NAME(ZONE_RESET_ALL), 107 REQ_OP_NAME(ZONE_OPEN), 108 REQ_OP_NAME(ZONE_CLOSE), 109 REQ_OP_NAME(ZONE_FINISH), 110 REQ_OP_NAME(ZONE_APPEND), 111 REQ_OP_NAME(WRITE_ZEROES), 112 REQ_OP_NAME(DRV_IN), 113 REQ_OP_NAME(DRV_OUT), 114 }; 115 #undef REQ_OP_NAME 116 117 /** 118 * blk_op_str - Return the string "name" for an operation REQ_OP_name. 119 * @op: a request operation. 120 * 121 * Convert a request operation REQ_OP_name into the string "name". Useful for 122 * debugging and tracing BIOs and requests. For an invalid request operation 123 * code, the string "UNKNOWN" is returned. 124 */ 125 inline const char *blk_op_str(enum req_op op) 126 { 127 const char *op_str = "UNKNOWN"; 128 129 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 130 op_str = blk_op_name[op]; 131 132 return op_str; 133 } 134 EXPORT_SYMBOL_GPL(blk_op_str); 135 136 enum req_op str_to_blk_op(const char *op) 137 { 138 int i; 139 140 for (i = 0; i < ARRAY_SIZE(blk_op_name); i++) 141 if (blk_op_name[i] && !strcmp(blk_op_name[i], op)) 142 return (enum req_op)i; 143 return REQ_OP_LAST; 144 } 145 146 #define ENT(_tag, _errno, _desc) \ 147 [BLK_STS_##_tag] = { \ 148 .errno = _errno, \ 149 .tag = __stringify(_tag), \ 150 .name = _desc, \ 151 } 152 static const struct { 153 int errno; 154 const char *tag; 155 const char *name; 156 } blk_errors[] = { 157 ENT(OK, 0, ""), 158 ENT(NOTSUPP, -EOPNOTSUPP, "operation not supported"), 159 ENT(TIMEOUT, -ETIMEDOUT, "timeout"), 160 ENT(NOSPC, -ENOSPC, "critical space allocation"), 161 ENT(TRANSPORT, -ENOLINK, "recoverable transport"), 162 ENT(TARGET, -EREMOTEIO, "critical target"), 163 ENT(RESV_CONFLICT, -EBADE, "reservation conflict"), 164 ENT(MEDIUM, -ENODATA, "critical medium"), 165 ENT(PROTECTION, -EILSEQ, "protection"), 166 ENT(RESOURCE, -ENOMEM, "kernel resource"), 167 ENT(DEV_RESOURCE, -EBUSY, "device resource"), 168 ENT(AGAIN, -EAGAIN, "nonblocking retry"), 169 ENT(OFFLINE, -ENODEV, "device offline"), 170 171 /* device mapper special case, should not leak out: */ 172 ENT(DM_REQUEUE, -EREMCHG, "dm internal retry"), 173 174 /* zone device specific errors */ 175 ENT(ZONE_OPEN_RESOURCE, -ETOOMANYREFS, "open zones exceeded"), 176 ENT(ZONE_ACTIVE_RESOURCE, -EOVERFLOW, "active zones exceeded"), 177 178 /* Command duration limit device-side timeout */ 179 ENT(DURATION_LIMIT, -ETIME, "duration limit exceeded"), 180 ENT(INVAL, -EINVAL, "invalid"), 181 182 /* everything else not covered above: */ 183 ENT(IOERR, -EIO, "I/O"), 184 }; 185 #undef ENT 186 187 blk_status_t errno_to_blk_status(int errno) 188 { 189 int i; 190 191 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 192 if (blk_errors[i].errno == errno) 193 return (__force blk_status_t)i; 194 } 195 196 return BLK_STS_IOERR; 197 } 198 EXPORT_SYMBOL_GPL(errno_to_blk_status); 199 200 int blk_status_to_errno(blk_status_t status) 201 { 202 int idx = (__force int)status; 203 204 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 205 return -EIO; 206 return blk_errors[idx].errno; 207 } 208 EXPORT_SYMBOL_GPL(blk_status_to_errno); 209 210 const char *blk_status_to_str(blk_status_t status) 211 { 212 int idx = (__force int)status; 213 214 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 215 return "<null>"; 216 return blk_errors[idx].name; 217 } 218 219 const char *blk_status_to_tag(blk_status_t status) 220 { 221 int idx = (__force int)status; 222 223 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors) || !blk_errors[idx].tag)) 224 return "<null>"; 225 return blk_errors[idx].tag; 226 } 227 228 blk_status_t tag_to_blk_status(const char *tag) 229 { 230 int i; 231 232 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 233 if (blk_errors[i].tag && 234 !strcmp(blk_errors[i].tag, tag)) 235 return (__force blk_status_t)i; 236 } 237 238 /* 239 * Return BLK_STS_OK for mismatches as this function is intended to 240 * parse error status values. 241 */ 242 return BLK_STS_OK; 243 } 244 245 /** 246 * blk_sync_queue - cancel any pending callbacks on a queue 247 * @q: the queue 248 * 249 * Description: 250 * The block layer may perform asynchronous callback activity 251 * on a queue, such as calling the unplug function after a timeout. 252 * A block device may call blk_sync_queue to ensure that any 253 * such activity is cancelled, thus allowing it to release resources 254 * that the callbacks might use. The caller must already have made sure 255 * that its ->submit_bio will not re-add plugging prior to calling 256 * this function. 257 * 258 * This function does not cancel any asynchronous activity arising 259 * out of elevator or throttling code. That would require elevator_exit() 260 * and blkcg_exit_queue() to be called with queue lock initialized. 261 * 262 */ 263 void blk_sync_queue(struct request_queue *q) 264 { 265 timer_delete_sync(&q->timeout); 266 cancel_work_sync(&q->timeout_work); 267 } 268 EXPORT_SYMBOL(blk_sync_queue); 269 270 /** 271 * blk_set_pm_only - increment pm_only counter 272 * @q: request queue pointer 273 */ 274 void blk_set_pm_only(struct request_queue *q) 275 { 276 atomic_inc(&q->pm_only); 277 } 278 EXPORT_SYMBOL_GPL(blk_set_pm_only); 279 280 void blk_clear_pm_only(struct request_queue *q) 281 { 282 int pm_only; 283 284 pm_only = atomic_dec_return(&q->pm_only); 285 WARN_ON_ONCE(pm_only < 0); 286 if (pm_only == 0) 287 wake_up_all(&q->mq_freeze_wq); 288 } 289 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 290 291 static void blk_free_queue_rcu(struct rcu_head *rcu_head) 292 { 293 struct request_queue *q = container_of(rcu_head, 294 struct request_queue, rcu_head); 295 296 percpu_ref_exit(&q->q_usage_counter); 297 kmem_cache_free(blk_requestq_cachep, q); 298 } 299 300 static void blk_free_queue(struct request_queue *q) 301 { 302 blk_free_queue_stats(q->stats); 303 if (queue_is_mq(q)) 304 blk_mq_release(q); 305 306 ida_free(&blk_queue_ida, q->id); 307 lockdep_unregister_key(&q->io_lock_cls_key); 308 lockdep_unregister_key(&q->q_lock_cls_key); 309 call_rcu(&q->rcu_head, blk_free_queue_rcu); 310 } 311 312 /** 313 * blk_put_queue - decrement the request_queue refcount 314 * @q: the request_queue structure to decrement the refcount for 315 * 316 * Decrements the refcount of the request_queue and free it when the refcount 317 * reaches 0. 318 */ 319 void blk_put_queue(struct request_queue *q) 320 { 321 if (refcount_dec_and_test(&q->refs)) 322 blk_free_queue(q); 323 } 324 EXPORT_SYMBOL(blk_put_queue); 325 326 bool blk_queue_start_drain(struct request_queue *q) 327 { 328 /* 329 * When queue DYING flag is set, we need to block new req 330 * entering queue, so we call blk_freeze_queue_start() to 331 * prevent I/O from crossing blk_queue_enter(). 332 */ 333 bool freeze = __blk_freeze_queue_start(q, current); 334 if (queue_is_mq(q)) 335 blk_mq_wake_waiters(q); 336 /* Make blk_queue_enter() reexamine the DYING flag. */ 337 wake_up_all(&q->mq_freeze_wq); 338 339 return freeze; 340 } 341 342 /** 343 * blk_queue_enter() - try to increase q->q_usage_counter 344 * @q: request queue pointer 345 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM 346 */ 347 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 348 { 349 const bool pm = flags & BLK_MQ_REQ_PM; 350 351 while (!blk_try_enter_queue(q, pm)) { 352 if (flags & BLK_MQ_REQ_NOWAIT) 353 return -EAGAIN; 354 355 /* 356 * read pair of barrier in blk_freeze_queue_start(), we need to 357 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 358 * reading .mq_freeze_depth or queue dying flag, otherwise the 359 * following wait may never return if the two reads are 360 * reordered. 361 */ 362 smp_rmb(); 363 wait_event(q->mq_freeze_wq, 364 (!q->mq_freeze_depth && 365 blk_pm_resume_queue(pm, q)) || 366 blk_queue_dying(q)); 367 if (blk_queue_dying(q)) 368 return -ENODEV; 369 } 370 371 rwsem_acquire_read(&q->q_lockdep_map, 0, 0, _RET_IP_); 372 rwsem_release(&q->q_lockdep_map, _RET_IP_); 373 return 0; 374 } 375 376 int __bio_queue_enter(struct request_queue *q, struct bio *bio) 377 { 378 while (!blk_try_enter_queue(q, false)) { 379 struct gendisk *disk = bio->bi_bdev->bd_disk; 380 381 if (bio->bi_opf & REQ_NOWAIT) { 382 if (test_bit(GD_DEAD, &disk->state)) 383 goto dead; 384 bio_wouldblock_error(bio); 385 return -EAGAIN; 386 } 387 388 /* 389 * read pair of barrier in blk_freeze_queue_start(), we need to 390 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 391 * reading .mq_freeze_depth or queue dying flag, otherwise the 392 * following wait may never return if the two reads are 393 * reordered. 394 */ 395 smp_rmb(); 396 wait_event(q->mq_freeze_wq, 397 (!q->mq_freeze_depth && 398 blk_pm_resume_queue(false, q)) || 399 test_bit(GD_DEAD, &disk->state)); 400 if (test_bit(GD_DEAD, &disk->state)) 401 goto dead; 402 } 403 404 rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_); 405 rwsem_release(&q->io_lockdep_map, _RET_IP_); 406 return 0; 407 dead: 408 bio_io_error(bio); 409 return -ENODEV; 410 } 411 412 void blk_queue_exit(struct request_queue *q) 413 { 414 percpu_ref_put(&q->q_usage_counter); 415 } 416 417 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 418 { 419 struct request_queue *q = 420 container_of(ref, struct request_queue, q_usage_counter); 421 422 wake_up_all(&q->mq_freeze_wq); 423 } 424 425 static void blk_rq_timed_out_timer(struct timer_list *t) 426 { 427 struct request_queue *q = timer_container_of(q, t, timeout); 428 429 kblockd_schedule_work(&q->timeout_work); 430 } 431 432 static void blk_timeout_work(struct work_struct *work) 433 { 434 } 435 436 struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id) 437 { 438 struct request_queue *q; 439 int error; 440 441 q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO, 442 node_id); 443 if (!q) 444 return ERR_PTR(-ENOMEM); 445 446 q->last_merge = NULL; 447 448 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL); 449 if (q->id < 0) { 450 error = q->id; 451 goto fail_q; 452 } 453 454 q->stats = blk_alloc_queue_stats(); 455 if (!q->stats) { 456 error = -ENOMEM; 457 goto fail_id; 458 } 459 460 error = blk_set_default_limits(lim); 461 if (error) 462 goto fail_stats; 463 q->limits = *lim; 464 465 q->node = node_id; 466 467 atomic_set(&q->nr_active_requests_shared_tags, 0); 468 469 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 470 INIT_WORK(&q->timeout_work, blk_timeout_work); 471 INIT_LIST_HEAD(&q->icq_list); 472 473 refcount_set(&q->refs, 1); 474 mutex_init(&q->debugfs_mutex); 475 mutex_init(&q->elevator_lock); 476 mutex_init(&q->sysfs_lock); 477 mutex_init(&q->limits_lock); 478 mutex_init(&q->rq_qos_mutex); 479 spin_lock_init(&q->queue_lock); 480 481 init_waitqueue_head(&q->mq_freeze_wq); 482 mutex_init(&q->mq_freeze_lock); 483 484 blkg_init_queue(q); 485 486 /* 487 * Init percpu_ref in atomic mode so that it's faster to shutdown. 488 * See blk_register_queue() for details. 489 */ 490 error = percpu_ref_init(&q->q_usage_counter, 491 blk_queue_usage_counter_release, 492 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL); 493 if (error) 494 goto fail_stats; 495 lockdep_register_key(&q->io_lock_cls_key); 496 lockdep_register_key(&q->q_lock_cls_key); 497 lockdep_init_map(&q->io_lockdep_map, "&q->q_usage_counter(io)", 498 &q->io_lock_cls_key, 0); 499 lockdep_init_map(&q->q_lockdep_map, "&q->q_usage_counter(queue)", 500 &q->q_lock_cls_key, 0); 501 502 /* Teach lockdep about lock ordering (reclaim WRT queue freeze lock). */ 503 fs_reclaim_acquire(GFP_KERNEL); 504 rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_); 505 rwsem_release(&q->io_lockdep_map, _RET_IP_); 506 fs_reclaim_release(GFP_KERNEL); 507 508 q->nr_requests = BLKDEV_DEFAULT_RQ; 509 q->async_depth = BLKDEV_DEFAULT_RQ; 510 511 return q; 512 513 fail_stats: 514 blk_free_queue_stats(q->stats); 515 fail_id: 516 ida_free(&blk_queue_ida, q->id); 517 fail_q: 518 kmem_cache_free(blk_requestq_cachep, q); 519 return ERR_PTR(error); 520 } 521 522 /** 523 * blk_get_queue - increment the request_queue refcount 524 * @q: the request_queue structure to increment the refcount for 525 * 526 * Increment the refcount of the request_queue kobject. 527 * 528 * Context: Any context. 529 */ 530 bool blk_get_queue(struct request_queue *q) 531 { 532 if (unlikely(blk_queue_dying(q))) 533 return false; 534 refcount_inc(&q->refs); 535 return true; 536 } 537 EXPORT_SYMBOL(blk_get_queue); 538 539 #ifdef CONFIG_FAIL_MAKE_REQUEST 540 541 static DECLARE_FAULT_ATTR(fail_make_request); 542 543 static int __init setup_fail_make_request(char *str) 544 { 545 return setup_fault_attr(&fail_make_request, str); 546 } 547 __setup("fail_make_request=", setup_fail_make_request); 548 549 bool should_fail_request(struct block_device *part, unsigned int bytes) 550 { 551 return bdev_test_flag(part, BD_MAKE_IT_FAIL) && 552 should_fail(&fail_make_request, bytes); 553 } 554 555 static int __init fail_make_request_debugfs(void) 556 { 557 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 558 NULL, &fail_make_request); 559 560 return PTR_ERR_OR_ZERO(dir); 561 } 562 563 late_initcall(fail_make_request_debugfs); 564 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 565 566 static inline void bio_check_ro(struct bio *bio) 567 { 568 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 569 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 570 return; 571 572 if (bdev_test_flag(bio->bi_bdev, BD_RO_WARNED)) 573 return; 574 575 bdev_set_flag(bio->bi_bdev, BD_RO_WARNED); 576 577 /* 578 * Use ioctl to set underlying disk of raid/dm to read-only 579 * will trigger this. 580 */ 581 pr_warn("Trying to write to read-only block-device %pg\n", 582 bio->bi_bdev); 583 } 584 } 585 586 int should_fail_bio(struct bio *bio) 587 { 588 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 589 return -EIO; 590 return 0; 591 } 592 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 593 594 /* 595 * Check whether this bio extends beyond the end of the device or partition. 596 * This may well happen - the kernel calls bread() without checking the size of 597 * the device, e.g., when mounting a file system. 598 */ 599 static inline int bio_check_eod(struct bio *bio) 600 { 601 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 602 unsigned int nr_sectors = bio_sectors(bio); 603 604 if (nr_sectors && 605 (nr_sectors > maxsector || 606 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 607 if (!maxsector) 608 return -EIO; 609 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 610 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 611 current->comm, bio->bi_bdev, bio->bi_opf, 612 bio->bi_iter.bi_sector, nr_sectors, maxsector); 613 return -EIO; 614 } 615 return 0; 616 } 617 618 /* 619 * Remap block n of partition p to block n+start(p) of the disk. 620 */ 621 static int blk_partition_remap(struct bio *bio) 622 { 623 struct block_device *p = bio->bi_bdev; 624 625 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 626 return -EIO; 627 if (bio_sectors(bio)) { 628 bio->bi_iter.bi_sector += p->bd_start_sect; 629 trace_block_bio_remap(bio, p->bd_dev, 630 bio->bi_iter.bi_sector - 631 p->bd_start_sect); 632 } 633 bio_set_flag(bio, BIO_REMAPPED); 634 return 0; 635 } 636 637 /* 638 * Check write append to a zoned block device. 639 */ 640 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 641 struct bio *bio) 642 { 643 int nr_sectors = bio_sectors(bio); 644 645 /* Only applicable to zoned block devices */ 646 if (!bdev_is_zoned(bio->bi_bdev)) 647 return BLK_STS_NOTSUPP; 648 649 /* The bio sector must point to the start of a sequential zone */ 650 if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector)) 651 return BLK_STS_IOERR; 652 653 /* 654 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 655 * split and could result in non-contiguous sectors being written in 656 * different zones. 657 */ 658 if (nr_sectors > q->limits.chunk_sectors) 659 return BLK_STS_IOERR; 660 661 /* Make sure the BIO is small enough and will not get split */ 662 if (nr_sectors > q->limits.max_zone_append_sectors) 663 return BLK_STS_IOERR; 664 665 bio->bi_opf |= REQ_NOMERGE; 666 667 return BLK_STS_OK; 668 } 669 670 static void __submit_bio(struct bio *bio) 671 { 672 /* If plug is not used, add new plug here to cache nsecs time. */ 673 struct blk_plug plug; 674 675 blk_start_plug(&plug); 676 677 if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) { 678 blk_mq_submit_bio(bio); 679 } else if (likely(bio_queue_enter(bio) == 0)) { 680 struct gendisk *disk = bio->bi_bdev->bd_disk; 681 682 if ((bio->bi_opf & REQ_POLLED) && 683 !(disk->queue->limits.features & BLK_FEAT_POLL)) 684 bio_endio_status(bio, BLK_STS_NOTSUPP); 685 else 686 disk->fops->submit_bio(bio); 687 blk_queue_exit(disk->queue); 688 } 689 690 blk_finish_plug(&plug); 691 } 692 693 /* 694 * The loop in this function may be a bit non-obvious, and so deserves some 695 * explanation: 696 * 697 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 698 * that), so we have a list with a single bio. 699 * - We pretend that we have just taken it off a longer list, so we assign 700 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 701 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 702 * bios through a recursive call to submit_bio_noacct. If it did, we find a 703 * non-NULL value in bio_list and re-enter the loop from the top. 704 * - In this case we really did just take the bio off the top of the list (no 705 * pretending) and so remove it from bio_list, and call into ->submit_bio() 706 * again. 707 * 708 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 709 * bio_list_on_stack[1] contains bios that were submitted before the current 710 * ->submit_bio(), but that haven't been processed yet. 711 */ 712 static void __submit_bio_noacct(struct bio *bio) 713 { 714 struct bio_list bio_list_on_stack[2]; 715 716 BUG_ON(bio->bi_next); 717 718 bio_list_init(&bio_list_on_stack[0]); 719 current->bio_list = bio_list_on_stack; 720 721 do { 722 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 723 struct bio_list lower, same; 724 725 /* 726 * Create a fresh bio_list for all subordinate requests. 727 */ 728 bio_list_on_stack[1] = bio_list_on_stack[0]; 729 bio_list_init(&bio_list_on_stack[0]); 730 731 __submit_bio(bio); 732 733 /* 734 * Sort new bios into those for a lower level and those for the 735 * same level. 736 */ 737 bio_list_init(&lower); 738 bio_list_init(&same); 739 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 740 if (q == bdev_get_queue(bio->bi_bdev)) 741 bio_list_add(&same, bio); 742 else 743 bio_list_add(&lower, bio); 744 745 /* 746 * Now assemble so we handle the lowest level first. 747 */ 748 bio_list_merge(&bio_list_on_stack[0], &lower); 749 bio_list_merge(&bio_list_on_stack[0], &same); 750 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 751 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 752 753 current->bio_list = NULL; 754 } 755 756 static void __submit_bio_noacct_mq(struct bio *bio) 757 { 758 struct bio_list bio_list[2] = { }; 759 760 current->bio_list = bio_list; 761 762 do { 763 __submit_bio(bio); 764 } while ((bio = bio_list_pop(&bio_list[0]))); 765 766 current->bio_list = NULL; 767 } 768 769 void submit_bio_noacct_nocheck(struct bio *bio, bool split) 770 { 771 if (unlikely(blk_error_inject(bio))) 772 return; 773 774 blk_cgroup_bio_start(bio); 775 776 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 777 trace_block_bio_queue(bio); 778 /* 779 * Now that enqueuing has been traced, we need to trace 780 * completion as well. 781 */ 782 bio_set_flag(bio, BIO_TRACE_COMPLETION); 783 } 784 785 /* 786 * We only want one ->submit_bio to be active at a time, else stack 787 * usage with stacked devices could be a problem. Use current->bio_list 788 * to collect a list of requests submitted by a ->submit_bio method 789 * while it is active, and then process them after it returned. 790 */ 791 if (current->bio_list) { 792 if (split) 793 bio_list_add_head(¤t->bio_list[0], bio); 794 else 795 bio_list_add(¤t->bio_list[0], bio); 796 } else if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) { 797 __submit_bio_noacct_mq(bio); 798 } else { 799 __submit_bio_noacct(bio); 800 } 801 } 802 803 static blk_status_t blk_validate_atomic_write_op_size(struct request_queue *q, 804 struct bio *bio) 805 { 806 if (bio->bi_iter.bi_size > queue_atomic_write_unit_max_bytes(q)) 807 return BLK_STS_INVAL; 808 809 if (bio->bi_iter.bi_size % queue_atomic_write_unit_min_bytes(q)) 810 return BLK_STS_INVAL; 811 812 return BLK_STS_OK; 813 } 814 815 /** 816 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 817 * @bio: The bio describing the location in memory and on the device. 818 * 819 * This is a version of submit_bio() that shall only be used for I/O that is 820 * resubmitted to lower level drivers by stacking block drivers. All file 821 * systems and other upper level users of the block layer should use 822 * submit_bio() instead. 823 */ 824 void submit_bio_noacct(struct bio *bio) 825 { 826 struct block_device *bdev = bio->bi_bdev; 827 struct request_queue *q = bdev_get_queue(bdev); 828 blk_status_t status = BLK_STS_IOERR; 829 830 might_sleep(); 831 832 /* 833 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 834 * if queue does not support NOWAIT. 835 */ 836 if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev)) 837 goto not_supported; 838 839 if (bio_has_crypt_ctx(bio)) { 840 if (WARN_ON_ONCE(!bio_has_data(bio))) 841 goto end_io; 842 if (!blk_crypto_supported(bio)) 843 goto not_supported; 844 } 845 846 if (should_fail_bio(bio)) 847 goto end_io; 848 bio_check_ro(bio); 849 if (!bio_flagged(bio, BIO_REMAPPED)) { 850 if (unlikely(bio_check_eod(bio))) 851 goto end_io; 852 if (bdev_is_partition(bdev) && 853 unlikely(blk_partition_remap(bio))) 854 goto end_io; 855 } 856 857 /* 858 * Filter flush bio's early so that bio based drivers without flush 859 * support don't have to worry about them. 860 */ 861 if (op_is_flush(bio->bi_opf)) { 862 if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE && 863 bio_op(bio) != REQ_OP_ZONE_APPEND)) 864 goto end_io; 865 if (!bdev_write_cache(bdev)) { 866 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 867 if (!bio_sectors(bio)) { 868 status = BLK_STS_OK; 869 goto end_io; 870 } 871 } 872 } 873 874 switch (bio_op(bio)) { 875 case REQ_OP_READ: 876 break; 877 case REQ_OP_WRITE: 878 if (bio->bi_opf & REQ_ATOMIC) { 879 status = blk_validate_atomic_write_op_size(q, bio); 880 if (status != BLK_STS_OK) 881 goto end_io; 882 } 883 break; 884 case REQ_OP_FLUSH: 885 /* 886 * REQ_OP_FLUSH can't be submitted through bios, it is only 887 * synthetized in struct request by the flush state machine. 888 */ 889 goto not_supported; 890 case REQ_OP_DISCARD: 891 if (!bdev_max_discard_sectors(bdev)) 892 goto not_supported; 893 break; 894 case REQ_OP_SECURE_ERASE: 895 if (!bdev_max_secure_erase_sectors(bdev)) 896 goto not_supported; 897 break; 898 case REQ_OP_ZONE_APPEND: 899 status = blk_check_zone_append(q, bio); 900 if (status != BLK_STS_OK) 901 goto end_io; 902 break; 903 case REQ_OP_WRITE_ZEROES: 904 if (!q->limits.max_write_zeroes_sectors) 905 goto not_supported; 906 break; 907 case REQ_OP_ZONE_RESET: 908 case REQ_OP_ZONE_OPEN: 909 case REQ_OP_ZONE_CLOSE: 910 case REQ_OP_ZONE_FINISH: 911 case REQ_OP_ZONE_RESET_ALL: 912 if (!bdev_is_zoned(bio->bi_bdev)) 913 goto not_supported; 914 break; 915 case REQ_OP_DRV_IN: 916 case REQ_OP_DRV_OUT: 917 /* 918 * Driver private operations are only used with passthrough 919 * requests. 920 */ 921 fallthrough; 922 default: 923 goto not_supported; 924 } 925 926 if (blk_throtl_bio(bio)) 927 return; 928 submit_bio_noacct_nocheck(bio, false); 929 return; 930 931 not_supported: 932 status = BLK_STS_NOTSUPP; 933 end_io: 934 bio_endio_status(bio, status); 935 } 936 EXPORT_SYMBOL(submit_bio_noacct); 937 938 static void bio_set_ioprio(struct bio *bio) 939 { 940 /* Nobody set ioprio so far? Initialize it based on task's nice value */ 941 if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE) 942 bio->bi_ioprio = get_current_ioprio(); 943 blkcg_set_ioprio(bio); 944 } 945 946 /** 947 * submit_bio - submit a bio to the block device layer for I/O 948 * @bio: The &struct bio which describes the I/O 949 * 950 * submit_bio() is used to submit I/O requests to block devices. It is passed a 951 * fully set up &struct bio that describes the I/O that needs to be done. The 952 * bio will be sent to the device described by the bi_bdev field. 953 * 954 * The success/failure status of the request, along with notification of 955 * completion, is delivered asynchronously through the ->bi_end_io() callback 956 * in @bio. The bio must NOT be touched by the caller until ->bi_end_io() has 957 * been called. 958 */ 959 void submit_bio(struct bio *bio) 960 { 961 if (bio_op(bio) == REQ_OP_READ) { 962 task_io_account_read(bio->bi_iter.bi_size); 963 count_vm_events(PGPGIN, bio_sectors(bio)); 964 } else if (bio_op(bio) == REQ_OP_WRITE) { 965 count_vm_events(PGPGOUT, bio_sectors(bio)); 966 } 967 968 bio_set_ioprio(bio); 969 submit_bio_noacct(bio); 970 } 971 EXPORT_SYMBOL(submit_bio); 972 973 /** 974 * bio_poll - poll for BIO completions 975 * @bio: bio to poll for 976 * @iob: batches of IO 977 * @flags: BLK_POLL_* flags that control the behavior 978 * 979 * Poll for completions on queue associated with the bio. Returns number of 980 * completed entries found. 981 * 982 * Note: the caller must either be the context that submitted @bio, or 983 * be in a RCU critical section to prevent freeing of @bio. 984 */ 985 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 986 { 987 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 988 struct block_device *bdev; 989 struct request_queue *q; 990 int ret = 0; 991 992 bdev = READ_ONCE(bio->bi_bdev); 993 if (!bdev) 994 return 0; 995 996 q = bdev_get_queue(bdev); 997 if (cookie == BLK_QC_T_NONE) 998 return 0; 999 1000 blk_flush_plug(current->plug, false); 1001 1002 /* 1003 * We need to be able to enter a frozen queue, similar to how 1004 * timeouts also need to do that. If that is blocked, then we can 1005 * have pending IO when a queue freeze is started, and then the 1006 * wait for the freeze to finish will wait for polled requests to 1007 * timeout as the poller is preventer from entering the queue and 1008 * completing them. As long as we prevent new IO from being queued, 1009 * that should be all that matters. 1010 */ 1011 if (!percpu_ref_tryget(&q->q_usage_counter)) 1012 return 0; 1013 if (queue_is_mq(q)) { 1014 ret = blk_mq_poll(q, cookie, iob, flags); 1015 } else { 1016 struct gendisk *disk = q->disk; 1017 1018 if ((q->limits.features & BLK_FEAT_POLL) && disk && 1019 disk->fops->poll_bio) 1020 ret = disk->fops->poll_bio(bio, iob, flags); 1021 } 1022 blk_queue_exit(q); 1023 return ret; 1024 } 1025 EXPORT_SYMBOL_GPL(bio_poll); 1026 1027 /* 1028 * Helper to implement file_operations.iopoll. Requires the bio to be stored 1029 * in iocb->private, and cleared before freeing the bio. 1030 */ 1031 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 1032 unsigned int flags) 1033 { 1034 struct bio *bio; 1035 int ret = 0; 1036 1037 /* 1038 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 1039 * point to a freshly allocated bio at this point. If that happens 1040 * we have a few cases to consider: 1041 * 1042 * 1) the bio is being initialized and bi_bdev is NULL. We can just 1043 * simply nothing in this case 1044 * 2) the bio points to a not poll enabled device. bio_poll will catch 1045 * this and return 0 1046 * 3) the bio points to a poll capable device, including but not 1047 * limited to the one that the original bio pointed to. In this 1048 * case we will call into the actual poll method and poll for I/O, 1049 * even if we don't need to, but it won't cause harm either. 1050 * 1051 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 1052 * is still allocated. Because partitions hold a reference to the whole 1053 * device bdev and thus disk, the disk is also still valid. Grabbing 1054 * a reference to the queue in bio_poll() ensures the hctxs and requests 1055 * are still valid as well. 1056 */ 1057 rcu_read_lock(); 1058 bio = READ_ONCE(kiocb->private); 1059 if (bio) 1060 ret = bio_poll(bio, iob, flags); 1061 rcu_read_unlock(); 1062 1063 return ret; 1064 } 1065 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 1066 1067 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 1068 { 1069 unsigned long stamp; 1070 again: 1071 stamp = READ_ONCE(part->bd_stamp); 1072 if (unlikely(time_after(now, stamp)) && 1073 likely(try_cmpxchg(&part->bd_stamp, &stamp, now)) && 1074 (end || bdev_count_inflight(part))) 1075 __part_stat_add(part, io_ticks, now - stamp); 1076 1077 if (bdev_is_partition(part)) { 1078 part = bdev_whole(part); 1079 goto again; 1080 } 1081 } 1082 1083 unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op, 1084 unsigned long start_time) 1085 { 1086 part_stat_lock(); 1087 update_io_ticks(bdev, start_time, false); 1088 bdev_inc_in_flight(bdev, op); 1089 part_stat_unlock(); 1090 1091 return start_time; 1092 } 1093 EXPORT_SYMBOL(bdev_start_io_acct); 1094 1095 /** 1096 * bio_start_io_acct - start I/O accounting for bio based drivers 1097 * @bio: bio to start account for 1098 * 1099 * Returns the start time that should be passed back to bio_end_io_acct(). 1100 */ 1101 unsigned long bio_start_io_acct(struct bio *bio) 1102 { 1103 return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies); 1104 } 1105 EXPORT_SYMBOL_GPL(bio_start_io_acct); 1106 1107 void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 1108 unsigned int sectors, unsigned long start_time) 1109 { 1110 const int sgrp = op_stat_group(op); 1111 unsigned long now = READ_ONCE(jiffies); 1112 unsigned long duration = now - start_time; 1113 1114 part_stat_lock(); 1115 update_io_ticks(bdev, now, true); 1116 part_stat_inc(bdev, ios[sgrp]); 1117 part_stat_add(bdev, sectors[sgrp], sectors); 1118 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 1119 bdev_dec_in_flight(bdev, op); 1120 part_stat_unlock(); 1121 } 1122 EXPORT_SYMBOL(bdev_end_io_acct); 1123 1124 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1125 struct block_device *orig_bdev) 1126 { 1127 bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time); 1128 } 1129 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1130 1131 /** 1132 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1133 * @q : the queue of the device being checked 1134 * 1135 * Description: 1136 * Check if underlying low-level drivers of a device are busy. 1137 * If the drivers want to export their busy state, they must set own 1138 * exporting function using blk_queue_lld_busy() first. 1139 * 1140 * Basically, this function is used only by request stacking drivers 1141 * to stop dispatching requests to underlying devices when underlying 1142 * devices are busy. This behavior helps more I/O merging on the queue 1143 * of the request stacking driver and prevents I/O throughput regression 1144 * on burst I/O load. 1145 * 1146 * Return: 1147 * 0 - Not busy (The request stacking driver should dispatch request) 1148 * 1 - Busy (The request stacking driver should stop dispatching request) 1149 */ 1150 int blk_lld_busy(struct request_queue *q) 1151 { 1152 if (queue_is_mq(q) && q->mq_ops->busy) 1153 return q->mq_ops->busy(q); 1154 1155 return 0; 1156 } 1157 EXPORT_SYMBOL_GPL(blk_lld_busy); 1158 1159 int kblockd_schedule_work(struct work_struct *work) 1160 { 1161 return queue_work(kblockd_workqueue, work); 1162 } 1163 EXPORT_SYMBOL(kblockd_schedule_work); 1164 1165 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1166 unsigned long delay) 1167 { 1168 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1169 } 1170 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1171 1172 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1173 { 1174 struct task_struct *tsk = current; 1175 1176 /* 1177 * If this is a nested plug, don't actually assign it. 1178 */ 1179 if (tsk->plug) 1180 return; 1181 1182 plug->cur_ktime = 0; 1183 rq_list_init(&plug->mq_list); 1184 rq_list_init(&plug->cached_rqs); 1185 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1186 plug->rq_count = 0; 1187 plug->multiple_queues = false; 1188 plug->has_elevator = false; 1189 INIT_LIST_HEAD(&plug->cb_list); 1190 1191 /* 1192 * Store ordering should not be needed here, since a potential 1193 * preempt will imply a full memory barrier 1194 */ 1195 tsk->plug = plug; 1196 } 1197 1198 /** 1199 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1200 * @plug: The &struct blk_plug that needs to be initialized 1201 * 1202 * Description: 1203 * blk_start_plug() indicates to the block layer an intent by the caller 1204 * to submit multiple I/O requests in a batch. The block layer may use 1205 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1206 * is called. However, the block layer may choose to submit requests 1207 * before a call to blk_finish_plug() if the number of queued I/Os 1208 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1209 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1210 * the task schedules (see below). 1211 * 1212 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1213 * pending I/O should the task end up blocking between blk_start_plug() and 1214 * blk_finish_plug(). This is important from a performance perspective, but 1215 * also ensures that we don't deadlock. For instance, if the task is blocking 1216 * for a memory allocation, memory reclaim could end up wanting to free a 1217 * page belonging to that request that is currently residing in our private 1218 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1219 * this kind of deadlock. 1220 */ 1221 void blk_start_plug(struct blk_plug *plug) 1222 { 1223 blk_start_plug_nr_ios(plug, 1); 1224 } 1225 EXPORT_SYMBOL(blk_start_plug); 1226 1227 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1228 { 1229 LIST_HEAD(callbacks); 1230 1231 while (!list_empty(&plug->cb_list)) { 1232 list_splice_init(&plug->cb_list, &callbacks); 1233 1234 while (!list_empty(&callbacks)) { 1235 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1236 struct blk_plug_cb, 1237 list); 1238 list_del(&cb->list); 1239 cb->callback(cb, from_schedule); 1240 } 1241 } 1242 } 1243 1244 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1245 int size) 1246 { 1247 struct blk_plug *plug = current->plug; 1248 struct blk_plug_cb *cb; 1249 1250 if (!plug) 1251 return NULL; 1252 1253 list_for_each_entry(cb, &plug->cb_list, list) 1254 if (cb->callback == unplug && cb->data == data) 1255 return cb; 1256 1257 /* Not currently on the callback list */ 1258 BUG_ON(size < sizeof(*cb)); 1259 cb = kzalloc(size, GFP_ATOMIC); 1260 if (cb) { 1261 cb->data = data; 1262 cb->callback = unplug; 1263 list_add(&cb->list, &plug->cb_list); 1264 } 1265 return cb; 1266 } 1267 EXPORT_SYMBOL(blk_check_plugged); 1268 1269 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1270 { 1271 if (!list_empty(&plug->cb_list)) 1272 flush_plug_callbacks(plug, from_schedule); 1273 blk_mq_flush_plug_list(plug, from_schedule); 1274 /* 1275 * Unconditionally flush out cached requests, even if the unplug 1276 * event came from schedule. Since we know hold references to the 1277 * queue for cached requests, we don't want a blocked task holding 1278 * up a queue freeze/quiesce event. 1279 */ 1280 if (unlikely(!rq_list_empty(&plug->cached_rqs))) 1281 blk_mq_free_plug_rqs(plug); 1282 1283 plug->cur_ktime = 0; 1284 current->flags &= ~PF_BLOCK_TS; 1285 } 1286 1287 /** 1288 * blk_finish_plug - mark the end of a batch of submitted I/O 1289 * @plug: The &struct blk_plug passed to blk_start_plug() 1290 * 1291 * Description: 1292 * Indicate that a batch of I/O submissions is complete. This function 1293 * must be paired with an initial call to blk_start_plug(). The intent 1294 * is to allow the block layer to optimize I/O submission. See the 1295 * documentation for blk_start_plug() for more information. 1296 */ 1297 void blk_finish_plug(struct blk_plug *plug) 1298 { 1299 if (plug == current->plug) { 1300 __blk_flush_plug(plug, false); 1301 current->plug = NULL; 1302 } 1303 } 1304 EXPORT_SYMBOL(blk_finish_plug); 1305 1306 void blk_io_schedule(void) 1307 { 1308 /* Prevent hang_check timer from firing at us during very long I/O */ 1309 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1310 1311 if (timeout) 1312 io_schedule_timeout(timeout); 1313 else 1314 io_schedule(); 1315 } 1316 1317 int __init blk_dev_init(void) 1318 { 1319 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1320 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1321 sizeof_field(struct request, cmd_flags)); 1322 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1323 sizeof_field(struct bio, bi_opf)); 1324 1325 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1326 kblockd_workqueue = alloc_workqueue("kblockd", 1327 WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_PERCPU, 0); 1328 if (!kblockd_workqueue) 1329 panic("Failed to create kblockd\n"); 1330 1331 blk_requestq_cachep = KMEM_CACHE(request_queue, SLAB_PANIC); 1332 1333 blk_debugfs_root = debugfs_create_dir("block", NULL); 1334 1335 return 0; 1336 } 1337